Technical Assistance Consultant’s Report€¦ · Finnish Consulting Group Asia, Afghan Tarin Engineering Services, and CMS Engineering Consult. The views expressed herein do not

Technical Assistance Consultant’s Report

This consultant’s report does not necessarily reflect the views of ADB or the Government concerned, and ADB and the Government cannot be held liable for its contents. For project preparatory technical assistance: All the views expressed herein may not be incorporated into the proposed project’s design.

Project Number: 48096-001 April 2019

Islamic Republic of Afghanistan: Arghandab Integrated Water Resources Development Investment Program (Financed by the Afghanistan Infrastructure Trust Fund and Japan

Fund for Poverty Reduction)

Feasibility Study Report Component 1: Part A: Raising Dahla Dam and Six Saddle Dams Part B: Route Bearer Highway Realignment

Prepared by FCG ANZDEC, Prime Nimmo Bell Partners, Finnish Consulting Group Asia, Afghan Tarin Engineering Services, and CMS Engineering Consult

(Auckland, New Zealand; Singapore; Kabul, Afghanistan; and Kathmandu, Nepal)

For Asian Development Bank

CURRENCY EQUIVALENTS (as of 01 March 2019)

Currency unit – Afghanistan Afghani (AFN)

United State Dollars ($)

$ 1.00 = AFN 75.40

AFN 1.00 = $ 0.01312

ABBREVIATIONS

AASHTO – American Association of State Highway and Transportation Officials

ADB – Asian Development Bank AEP – Annual Exceedance Probability AMAC – Afghanistan Mine Action Centre ASBA – Arghandab Sub-basin Authority CIDA – Canadian International Development Agency CBR – California Bearing Ratio CSR – Current Schedule of Rates DABS – Da Afghanistan Breshna Sherkat DCF – Dam Crest Flood FOS – Factor of Safety FSL – Full Supply Level HAVA – Helmand and Arghandab Valley Authority HRB – Helmand River basin IDF – Inflow Design Flood IWRM – Integrated water resource management M&E – Monitoring and Evaluation MAIL – Ministry of Agriculture, Irrigation and Livestock MASL – Meters above sea level MEW – Ministry of Energy and Water MCE – Maximum Credible Earthquake MDE – Maximum Design Earthquake MPW – Ministry of Public works MRRD – Ministry of Rehabilitation and Rural Development NEPA – National Environment Protection Agency NHA – National Highway Authority O&M – Operation and maintenance OBE – Operational Basis Earthquake PGA – Peak Ground Acceleration PMF – Probable Maximum Flood ROW – Right-of-way SEPS – South East Power System SWAT – Soil and Water Assessment Tool TRTA – Transaction technical assistance USBR – United States Bureau of Reclamation USACE – United States Army Corps of Engineers USAID – United State Agency for International Development

WGS84 – World Geodetic System 1984

WEIGHTS AND MEASURES

°C – degree Celsius ha – hectare km – kilometer km² – square kilometer masl – meters above sea level m – meter m3 – cubic meter m/s – meter per second m3/s – cubic meter per second mm – millimeter r – density of material s – second T – ton

NOTE

(i) In this report, "$" refers to US dollars.

This report is a document of the association between FCG ANZDEC, Prime Nimmo Bell Partners, Finnish Consulting Group Asia, Afghan Tarin Engineering Services, and CMS Engineering Consult. The views expressed herein do not necessarily represent those of ADB's Board of Directors, Management, or staff, and may be preliminary in nature.

In preparing any country program or strategy, financing any project, or by making any designation of or reference to a particular territory or geographic area in this document, the association does not intend to make any judgments as to the legal or other status of any territory or area.

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EXECUTIVE SUMMARY

This feasibility study report of the proposed integrated water resources investment covers Component 1: Raising Dahla Dam and six saddle dams (Part A) 1 and Route Bearer Highway realignment (Part B).

The overall investment comprises four components: (i) Component 1 (this report): raising Dahla Dam to enhance water storage capacity; which will provide increased water available for (ii) Component 2: climate-smart irrigation and agriculture value chain development; (iii) Component 3: water supply for Kandahar; and (iv) Component 4: hydropower development. The proposed investment aims to improve water availability, efficient management of water resources, and improve water productivity in agriculture. The project is located in the sub-basin of the Arghandab River, a significant tributary of the Helmand River system.

Part A: Raising Dahla Dam and six saddle dams

Dahla Dam was constructed in 1952 to store 478 million m3 of water mainly for irrigation and flood control purposes, with the anticipated extension of the Arghandab reservoir water use for hydropower generation not being implemented. During 66 years of dam operation, the Arghandab reservoir has lost about 40% of water storage due to sedimentation and is currently estimated to store about 288 million m3 of water at Full Supply Level of 1,135.4 m (WGS84 elevation).

The Government of the Islamic Republic of Afghanistan has accepted the transaction technical assistance (TRTA) team’s recommendation for a dam raise of 13.6 m.

The TRTA hydrology study shows that an increase in reservoir full supply level due to raising Dahla Dam should nearly linearly increase irrigation water availability and reduce spill. Under driest future conditions, no irrigation water should be available for rest of the year for summer crops. However, benefits should be clearly visible under average and wet conditions. Under wet conditions of one year in ten, modelling shows spillway outflows will occur. However, under average conditions the spill at a 13.6 m raise should be zero. The practical limit of dam raise considering long term average flows may then be considered as 13.6 m. Further elevating the dam will not improve irrigation water reliability in average years, as reservoir inflow is the limiting factor.

Advantages of 13.6 m raise as compared to 9.1 m (equivalent to USACE’s 8.0 m) are (i) the marginal cost is low with some additional resettlement, (ii) it prolongs dam life by allowing increased sediment deposition before capacity falls too far, and (iii) allows increased water to be retained in the dam e.g., for late summer irrigation in wet years.

The dam raise will address key development constraints of water and power in the region, prolong dam’s life, ensure increased and more reliable irrigated agriculture and tailored interventions, supply piped water supply to city of Kandahar, and as a by-product provide hydropower generation of 130,000 MWhr/year or 35 to 40% of Kandahar power requirement.

Along with Kajaki, with an installed capacity of 51.5 MW, Dahla hydropower station will significantly contribute to the positive development of the region. This should give a substantial enhancement to the economic activities in the Kandahar region. Time for pay back of hydropower comprising 3 x 9.5 MW Francis / Kaplan are estimated as only 1.69 year of operation, as further detailed in Component 4 feasibility study.

1 This report is a further extension of the original feasibility report submitted in February 2019. Some additional details

are provided in this report like project scope has been extended to include park and Panel of Expert, the hydrology has been updated as per Ewater input, geotechnical data has been updated after receiving additional investigation, more details are added to various other outputs as per request of ADB/MEW, drawings have been updated and added and cost estimates have been updated with more refined data from various components.

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Based on this study, dam raising option of 13.6 m is technically feasible. The design is a robust and economical design and has been used in Australia on various dams.

Considering a 2.7 million m3 sedimentation rate, the raised reservoir should have over 200-year life. This study has highlighted significant opportunity to generate and add hydropower to the grid after corrections in the surveys and proposed a design with long-term benefits to the region. Due to the financially attractive hydropower production, the cost of dam raising should be recoverable in a short period of less than 10 years.

Installation of a seasonal flow forecasting system is recommended to optimize the operation of Dahla Dam to estimate demand and supply in a year for various components including irrigation, municipal, environmental and hydropower generation. This system will help estimating snowfall in Hindukush Mountains and likely inflows in Arghandab river. The cost of this system may be estimated during detailed design.

This report provides an evidence-based platform for making an investment decision by assessing proposed investment options for raising Dahla Dam for 13.6 m from technical and economic aspects. It includes feasibility level study design drawings. This report is a result of a comprehensive analysis of quantitative and qualitative data, and information collected from secondary and primary sources collected through TRTA field-level investigations (bathymetric survey in May 2018, topographic survey in November 2018, and geotechnical survey in December 2018). In addition, hydrology study utilizing the Soil and Water Assessment Tool (SWAT) for modelling climate change impacts on the reservoir hydrology and sedimentation, and dam safety analysis including analysis using GeoSlope (2018) software were conducted. This report has further extended the concept design (September 2018) for Dahla Dam raising to a feasibility design.

A separate multisector water allocation (MSWA) options study was prepared by the TRTA based on recent additional hydrological studies performed by EWater. Ewater is an Australian government owned company, that is undertaking inflow modelling for all Afghan basins. MSWA studies intends to provide guidance to Arghandab Sub-basin Authority in preparing regulations to manage the water received by the dam and distribute it among the various users and uses. Ewater estimates provide further look into water allocation, dam operations and economics of the project.

This investment in Dahla Dam raise, with the accompanying investment in improving Arghandab catchment water management, reservoir multisector water use, and Dahla Dam operation, has been identified as a long-term solution to provide more consistent water supply for municipal water, irrigation, hydropower and environmental flows.

The topographic survey conducted during TRTA has applied significant corrections in various structural elevations. There was a critical elevation error of 10.883 m in the previous elevation measurement of the outlet structures (penstocks and irrigation outlets). The WGS 84 elevation for the penstock was reported as 1101.15 m whereas actual WGS84 elevation was measured as 1090.267 m. Therefore, these structures are located deeper than reported and the estimated discharges released from the irrigation outlets were underestimated. This means that over the year, the actual irrigation supplies from the dam were higher as compared to the reported discharge by the Arghandab Sub-basin Authority (ASBA). It is recommended that discharges from the irrigation outlet be re-calibrated based on this correction. The charts / graphs used to estimate flows from both irrigation outlet and penstock need to be updated during the detailed design stage.

The hydraulics analysis validated that the dam crest height be kept to 1154 m with a 5.0 m free board at Full Supply Level and consistent with 1952 design free board for the dam. The recommended spillway raise to 13.6 m height will result in Full Supply Level of 1149 m. With the

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proposed design free board for the case of Probable Maximum Flood will be 1.7 m, which was 0.8 m as assessed in earlier studies.

Additional geotechnical investigations were also performed along various existing structures to make an informed decision on the dam feasibility design. The geotechnical investigation validated that along the Route Bearer Highway, a significant quantity of earth fill should be available for the dam construction. However, processing of this material will be required. As the reservoir area will increase from 29.54 to 45.81 km2 significant material from the existing and proposed raised dam should easily be available.

Typically, low reservoir volume periods are from July to November. Most construction could be planned in this period when there is minimal risk of spillway flows. The contractor must design their own coffer dams to protect spillways and structures under construction.

For final setting of the proposed dams and spillway structures, additional geotechnical investigations and model studies should be performed to finalize the dam extensions and design of the spillway 1 as per feasibility drawings.

The feasibility design added the following correction in siting of the new structures: Spillway 1 was relocated downstream of the existing spillway to minimize the cost of the new structure using existing natural rock hill abutments. This will require additional investigations along Spillway 1 during detailed design. The investigations should include boreholes along spillway length and boreholes along abutments. Additional geotechnical investigations for the detailed design of the Saddle Dam 6, main dam left abutment, trash rack structures, intake tower bridge and Route Bearer Highway before and during construction are also proposed.

The project component will have 17 outputs:

Raise of main dam and intake tower, tunnel lining and trash rack; Raise of Saddle Dam 6; Raise of Saddle Dams 4 and 5; Raise of Saddle Dams 3 to 1; Extension of Saddle Dam 1; Spillway 1; Spillway 2; Geotechnical instrumentation;

Site security fence; Electrification along dam; Resettlement; Road realignment;2 Operation and maintenance; Dam safety staff training; Staff colony and security camp; Park; Panel of experts (POE).

2 Further breakdown is provided in Part B

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Estimated base costs for project activities are $230.28 million excluding taxes and duties.

Output Indicative cost

($’ 000) Output 1: Raising of main dam 71,043

Output 2: Raising of Saddle Dam 6 13,562

Output 3: Raising of Saddle Dams 4 and 5 9,458

Output 4: Raise of Saddle Dams 3 to 1 8,038

Output 5: Extension of Saddle Dam 1 3,221

Output 6: Spillway 1 25,119


Output 8: Instrumentation 2,000

Output 9: Site security fence 1,000

Output 10: Electrification along dam 1,000

Output 11: Resettlement 10,529

Output 12: Road realignment * 16,360

Output 13: Operation and maintenance 5,000

Output 14: Dam safety staff training 2,000

Output 15: Staff colony and security camp 3,000

Output 16: Park 2,000

Output 17: International Panel of Experts (POE) 511

Subtotal (1 to 17) 190,314

Security (10% of Subtotal) 19,031

Contingencies (11% of Subtotal) 20,934

Total base cost 230,280

Taxes and duties -

TOTAL 230,280 * Further breakdown is provided in Part B Source: TRTA Consultants, 2019

Details of the project costs are provided as Appendix 1. Proposed project schedule is provided as Appendix 2. The output plots of Ewater updated hydrology are presented as Appendix 3. Revised Feasibility Drawings are presented as Appendix 4. Revised Feasibility Hydraulics Report is presented as Appendix 5. Revised Feasibility Structural Report is presented as Appendix 6. Documents received for study are presented as Appendix 7.

Part B: Route Bearer Highway Realignment

The proposed raise requires realignment of the existing Route Bearer Highway in Shah Wali Kot District of Kandahar, also known as Kandahar-Bamiyan Highway. Kandahar Ministry of Public Works with Public Works Authority manages the existing highway. Present Route Bearer Highway is a two-lane single carriage highway. It is 7.3 m wide of paved area and has 1.5 m shoulders on both sides. Existing alignment passes mainly along barren areas with limited or no inhabitant adjacent to it. There are numerous culverts and one causeway.

Previously, a 4.3 km long highway stretch was raised to accommodate 8 m dam raise. With the raising of the dam by 13.6 m, this stretch, and additional stretches on both sides need to be raised. In addition, during the present feasibility studies, it was noted that there was significant reach of the highway which would also require upgrade for safe travel for the road users. This realignment would therefore raise the Route Bearer Highway to a safe level above Dam Crest Flood: 1154 m.

Previously USACE estimated the cost for 4.6 km road realignment as $15 million. The tender was awarded for $6 million ($1.30 million/km). TRTA has estimated a cost of $16.3 million for 9.8 km

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($1.67 million/km) (excluding contingencies, security and design and supervision cost). This is consistent with previous project experience considering additional challenges and structures.

Option proposed by USACE for raising existing highway was reviewed by the TRTA, however, it was noted that existing road embankment at some reaches was raised up to 10 m with fill. Such an embankment may have slope stability risks due to likely piping and washing of fines from the embankment with reservoir water fluctuation. It was considered that the Route Bearer Highway may also need further widening in coming years which was not possible for a raised embankment. Therefore, it was decided to design a revised route alignment.

The proposed alignment was considered based on the following factors:

Safe travel for road users even in case of Dam Crest Flood (i.e. above 1154.0 m); Development of regional economic activities; Improvement of the living environment of citizens; Possibility for dual carriage way; Possibility of future extension to motorway; Minimum cut and fill or balance cut and fill; and Minimal effect on commute distance and travel time for users.

The Project includes the construction of permanent asphalt concrete pavement road to ensure smooth traffic flow, construction of box culverts for enhancement of drainage systems and installation of road safety facilities.

The project primarily comprises pavement and road culverts construction work. Moreover, the study reflects the design concept that no demolition of existing houses, buildings and trees along the project road will occur. Therefore, it could be concluded that there will be no serious or adverse impacts during the construction and operation stages.

The proposed realigned highway would be 9.3 km long and pass mostly through barren hilly terrain. The realignment includes 850 m stretch of existing highway for raise. The new construction would, therefore, be limited to about 8.45 km. There will be 23 culverts and 2 super passages along the route. Although there is a potential for a future bridge along super passage 2, no tunneling or bridge structure is foreseen along the route at present.

It was noted that several of the existing highway culverts were destroyed using Explosive ordinance attacks. These damaged culverts were unrepaired and non-functional with risk of flooding of the area above existing highway. No drains are provided along the existing route considering natural topography. No damage was noted due to non-availability of drains.

The proposed alignment from Chainage 4+600 to 5+200 i.e. 600 m long, would pass through Shahjuy village agriculture land. The Right-of-way (ROW) has been considered as 50 m from centerline. Considering the proposed ROW, a land of 30,000 m2 would be required for this highway. The above land has already been considered under resettlement due to reservoir / dam raise and no additional land acquisition should be required. However, in order to start realignment works, the land has to be acquired. Land acquisition will be a critical activity before the start of construction of the highway. The Resettlement surveys are in progress.

The proposed culverts along the re-routed highway would be either 610 mm or 910 mm circular pipe structures as per the American Association of State Highway and Transportation Officials (AASHTO) design practice. The number and pipe size have been designed based on the design flows. The super passages will also have 910 mm circular pipe structures as per AASHTO design practice.

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The proposed design speed for the highway has been kept as 80 km / hour. The pavement design has been performed for a 15 years period. A California Bearing Ratio (CBR) of 15 has been used for the pavement design.

The design has been performed in general to nearly balance out the cut and fill. This should minimize wastage and disposal issues. The unsuitable material will be disposed in landfills approved by the National Environment Protection Agency (NEPA) downstream of Main Dahla dam to ensure that the excavated does not interfere with existing streams or water ways.

There will be need for stockpiling and processing / screening of the excavated and borrow material. Borrow fill would be available from existing reservoir area. This may be performed at location downstream of the Saddle Dam 6 where previous contractors made their site offices.

Asphalt is likely to be imported from Quetta Pakistan, about 200 km from Kandahar or Iran. Stone and rock could be easily available from Kandahar.

Construction plant and equipment, including a crushing plant, asphalt plant, grader, rollers, and dump trucks are expected to be imported from neighboring countries such as Pakistan or Iran.

A lesson learned from the recent development works in the Afghan road sector is the high construction costs caused by the security situation and necessity of involving international contractors in most of the projects due to the difficulty of contracting suitable local road contractors.3 It is proposed that recommendations from the Asian Development Bank (ADB) TA No. 4371-AFG Master Plan for Road Network Improvement Project (Master Plan Component) - Draft Final Report, November 2005 should be followed for the bidding and construction of the road.

Project specifications mainly refer to the National Highway Authority (NHA), and Pakistan specifications as transport sector of the country is well developed. Due to proximity of Kandahar with Quetta, Composite Schedule Rates (CSR) of NHA with appropriate currency exchange and inflation factor are applied.

The project will have the following four outputs:

Output 1: Earth work: Output 2: Sub-base, Base course and Wearing course; Output 3: RCC Culverts and Causeways; and Output 4: Ancillary works.

While preliminary topographic and geotechnical surveys were undertaken during the TRTA, it is mandatory that the contractor shall perform detailed topographical and geotechnical survey along the route to validate design assumptions.

Estimated base costs for project activities are $16.361 million. The cost with 10 % security, 15 % contingency and 2% detailed design, project management and supervision is estimated at $20.778 million. The above cost is estimated based on Composite Schedule Rates (CSR) of National Highway Authority (NHA) Pakistan for Quetta (Baluchistan) with additional consideration of currency conversion and additional haulage. A factor of 2.25 was applied to these rates in consultation with MRRD.

3 Policy Paper 2.4: Financing of the Road Sector, Transport Sector Review, Final Report; MOT/MPW/MOCAT/ARDS;

Jan. 2004

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Output Indicative Cost

($’ 000) Output 1: Earth work 6,512

Output 2: Sub-base, Base course and Surface course 8,714

Output 3: RCC Culverts and Causeways 901

Output 4: Ancillary works 234

Subtotal base cost 16,361

Security (10% of subtotal) 1,636

Contingency (15% of subtotal) 2,454

Detailed design, project management, supervision (2% of subtotal) 327

TOTAL 20,778 Source: TRTA Consultants, 2019

Details of the project costs are provided as Appendix 8. Proposed project schedule is provided as Appendix 9. Project Specifications are provided as Appendix 10 and Tender Drawings as Appendix 11.

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CONTENTS PART A: RAISING DAHLA DAM AND SIX SADDLE DAMS

I. INTRODUCTION ...............................................................................................................16

A. Background to Transaction Technical Assistance ..............................................................16

B. Approach and Methodology Used in Project Design ...........................................................17

II. COMPONENT 1 - EXISTING SITUATION .........................................................................20

A. Overview of the Component 1 ............................................................................................20

B. Key Issues .........................................................................................................................20

C. Existing Dahla Dam Infrastructure ......................................................................................21

D. Principal Project Data .........................................................................................................22

E. Project Infrastructure ..........................................................................................................25

F. 1952 Assessments and Studies .........................................................................................25

G. Dam Safety ........................................................................................................................28

III. PROBLEM ANALYSIS ......................................................................................................29

A. The Core Problem ..............................................................................................................29

B. Summary of Key Issues of Infrastructure in Component 1 ..................................................30

IV. RATIONALE ......................................................................................................................33

A. Design Considerations and Lessons Learned ....................................................................33

B. Key Issues and Considerations ..........................................................................................33

C. Review of Project Hydrology ..............................................................................................34

D. Downstream Water Demands ............................................................................................40

E. Proposed Dam Raise .........................................................................................................41

V. PROPOSED DAM SAFETY UPGRADES ..........................................................................42

A. Proposed Design Raise ......................................................................................................42

B. Dam Safety Risks and Proposed Remedial Measures .......................................................42

VI. EMBANKMENT DESIGN ..................................................................................................45

A. General ..............................................................................................................................45

B. Borrow Areas Test Pits Investigations ................................................................................45

C. Dam Safety Inspection .......................................................................................................47

D. Design ................................................................................................................................48

E. Assessments and Studies ..................................................................................................49

VII. PROPOSED INVESTMENT PROJECT OUTLINE .............................................................57

A. Outputs and Activities ........................................................................................................57

B. Cost Estimates ...................................................................................................................64

C. Human Resources and Equipment .....................................................................................65

D. Procurement ......................................................................................................................66

E. Implementation ..................................................................................................................68

F. Governance .......................................................................................................................69

G. Safeguards .........................................................................................................................69

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H. Risks and Mitigation Measures ...........................................................................................70

VIII. PANEL OF EXPERT TERMS OF REFERENCE ................................................................72

A. General and Purpose .........................................................................................................72

B. Organization and Membership ...........................................................................................72

C. Specific Actions ..................................................................................................................74

D. Tender Preparation Phase .................................................................................................74

E. Construction Phase ............................................................................................................75

F. Long Term Operation Phase ..............................................................................................76

G. Implementation Duration and Contract ...............................................................................76

H. Support Services ................................................................................................................76

I. Meetings of the POE ..........................................................................................................77

J. Reporting ...........................................................................................................................77

K. Required Expertise and Inputs ...........................................................................................77

L. Criteria for Selection of Consultants ...................................................................................78

IX. REFERENCES ..................................................................................................................82

APPENDIXES (ATTACHMENTS).............................................................................................84

APPENDIX 1: FEASIBILITY COST ESTIMATES ......................................................................84

APPENDIX 2: PROPOSED PROJECT SCHEDULE .................................................................84

APPENDIX 3: EWATER HYDROLOGY ASSESSMENT ...........................................................84

APPENDIX 4: FEASIBILITY STUDY DRAWINGS ....................................................................84

APPENDIX 5: FEASIBILITY HYDRAULICS STUDY REPORT .................................................84

APPENDIX 6: FEASIBILITY STRUCTURES ANALYSIS REPORT ...........................................84

APPENDIX 7: DOCUMENTS RECEIVED FOR STUDY ............................................................84

PART B: ROUTE BEARER HIGHWAY REALIGNMENT

I. INTRODUCTION ...............................................................................................................86

II. EXISTING ROUTE BEARER HIGHWAY ...........................................................................87

A. Overview of the Transportation Sector ...............................................................................87

B. Existing Route Bearer Highway ..........................................................................................87

C. Key Issues .........................................................................................................................90

III. PROPOSED ROUTE BEARER HIGHWAY REALIGNMENT ............................................91

A. Approach and Methodology ...............................................................................................91

B. Proposed Route Bearer Highway Realignment ..................................................................92

C. Key Issues for Consideration Prior Construction ................................................................93

IV. DESIGN CONSIDERATIONS ............................................................................................96

A. Guidelines ..........................................................................................................................96

B. Climate and Rainfall ...........................................................................................................96

C. Hydrology and Drainage .....................................................................................................97

D. Topography and Vegetation ...............................................................................................98

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E. Geology and Soils ..............................................................................................................99

F. Road Classification .......................................................................................................... 100

G. Design Criteria ................................................................................................................. 101

H. Pavement Design ............................................................................................................. 102

V. PROPOSED PROJECT OUTLINE .................................................................................. 104

A. Outcome, Outputs and Activities ...................................................................................... 104

B. Cost Estimates ................................................................................................................. 106

C. Project Schedule .............................................................................................................. 107

D. Implementation Arrangements ......................................................................................... 107

E. Human Resources ........................................................................................................... 107

F. Equipment and Machinery ................................................................................................ 108

G. Social Considerations ...................................................................................................... 108

H. Environmental Considerations .......................................................................................... 108

VI. RISKS AND MITIGATING MEASURES .......................................................................... 110

REFERENCES ....................................................................................................................... 112

APPENDIXES (ATTACHMENTS)........................................................................................... 113

APPENDIX 8: ROAD REALIGNMENT COST ESTIMATES .................................................... 113

APPENDIX 9: ROAD REALIGNMENT PROJECT SCHEDULE .............................................. 113

APPENDIX 10: ROAD REALIGNMENT PROJECT SPECIFICATIONS .................................. 113

APPENDIX 11: ROAD REALIGNMENT DRAWINGS .............................................................. 113

List of Tables

Table 1. Principal Project Data ..................................................................................................22

Table 2. ASBA Release Schedule .............................................................................................29

Table 3. List of Streamflow Gaging Stations with Published Streamflow Statistics ....................35 Table 4. Borrow Area Investigation with Anticipated Material Availability Summary ..................45

Table 5. Return Period and PGA for Embankment OBE and MDE ............................................51

Table 6. Atterberg Limits Summary Dahla Dam ........................................................................52

Table 7. Proposed Material Parameters for Seepage, Stability and Stress Analyses ................55 Table 8. Design Criteria for Embankment Stability ....................................................................56

Table 9. Key Project Outputs ....................................................................................................57

Table 10. Proposed Procurement of emergency response equipment and vehicles ..................60

Table 11. Estimated Project Cost ..............................................................................................64 Table 12. Approximate number and categories of job opportunities ..........................................65

Table 13. Equipment and machinery required for Implementation .............................................66

Table 14. Consulting Services Packages ..................................................................................66

Table 15. Goods, Works, and Non-consulting Services Packages ............................................67 Table 16. Summary of Risks and Mitigating Measures ..............................................................70

Table 17. International Panel of Expert (IPOE) Input Missions Summary ..................................77

Table 18. National Panel of Expert (POE) Input Missions Summary .........................................78

Table 19. Criteria for Selection of Panel of Expert (POE) ..........................................................78 Table 20. POE Overall Tentative Work Schedule ......................................................................81

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Table 21. Summary of Maintenance Works ...............................................................................95

Table 22. Structure type, location and design details ................................................................98

Table 23. Road Design Standard of Afghanistan ..................................................................... 100 Table 24. Relationships between Functional Classification and Design Classes ...................... 100

Table 25. Outline of Realignment of part of Route Bearer Highway Development ................... 101

Table 26. Geometric Standards .............................................................................................. 101

Table 27. ESAL Estimation ..................................................................................................... 102 Table 28. Pavement Design .................................................................................................... 103

Table 29. Project Cost Estimates ............................................................................................ 106

Table 30. Approximate Number of Local Human Resources Required for Implementation ..... 107

Table 31. Equipment and Machinery Required for Implementation ......................................... 108 Table 32. Summary of Risks and Mitigating Measures ............................................................ 110

List of Figures

Figure 1. Dahla Dam: Main Embankment, Saddle Dams 1-6, and Spillways 1 and 2 ................22

Figure 2. Location of Stream Gauges ........................................................................................35 Figure 3. Historical Inflow Record for Arghandab River During 1948–1980 ...............................37

Figure 4. Updated Storage Capacity Curve for Dahla Reservoir ...............................................39

Figure 5. Percentage Increase of Annual Irrigation Water Availability for Different Scenarios ...41

Figure 6. Gradation Envelope of Clay Core Material .................................................................46 Figure 7. Gradation Envelope of Clay Core and Random Rolled Fill (Sandy Gravel) Material ...47

Figure 8. Crest Settlements of Central Core Dams (Dumped Rockfill) ......................................50

Figure 9. Friction Angle vs. Liquid Limit Plot ..............................................................................53

Figure 10. Existing Route Bearer Highway ................................................................................88 Figure 11. Photo of the Existing Route Bearer Highway ............................................................89

Figure 12. Photo of a Destroyed Culvert ...................................................................................90

Figure 13. Proposed Highway Realignment ..............................................................................92

Figure 14. Existing and Proposed Route Bearer Highway Alignments ......................................93 Figure 15. Mean annual rainfall pattern in Kandahar .................................................................96

Figure 16. Ten Year Rainfall Intensity-Duration Frequency Curves ...........................................97

Figure 17. Geology along the Proposed Route Bearer Highway Alignment ...............................99

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PART A: RAISING DAHLA DAM AND SIX SADDLE DAMS

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I. INTRODUCTION

A. Background to Transaction Technical Assistance

1. The Government of the Islamic Republic of Afghanistan (government) requested the Asian Development Bank (ADB) for technical assistance to prepare an investment project to improve water resource management, irrigated agriculture, domestic and industrial water supply for Kandahar City, and to augment electric power in Kandahar City and surrounds. A transaction technical assistance (TRTA) to prepare the Arghandab Integrated Water Resources Development Investment Project was approved by ADB on 8 December 2016, with a Letter of Agreement approved by the government on 17 January 2016. The Ministry of Energy and Water (MEW) is the lead counterpart agency supported by the Ministry of Agriculture, Irrigation and Livestock (MAIL) for the irrigation and agriculture component. At the provincial level, the Arghandab Sub-basin Authority (ASBA) has provided support.

2. The project aims to provide long-term sustainable solutions to acute shortage of water in sub-basin of the Arghandab River, one of major tributaries of the Helmand River, by augmenting the existing Dahla Dam located some 35 km north of Kandahar City, through raising of the dam height by 13.6 m, and developing hydroelectric power generation, and urban water supply in and around Kandahar City, and irrigated agriculture in the sub-basin. The proposed investment in total aims to improve water availability, efficient management of water resources, and water productivity in agriculture. The program of investment is envisaged to comprise four components:

Component 1: Raising Dahla Dam and six saddle dams – increasing water storage capacity;

Component 2: Irrigation and agriculture development – climate-smart productive use of water;

Component 3: Improving water supply for Kandahar City – increasing water for domestic and industrial use;

Component 4: Dahla Dam hydroelectric power development – increasing hydropower supplied to the national grid.

3. This report covers Component 1: Raising Dahla Dam and six saddle dams – increasing water storage capacity. This report provides an evidence-based platform for making an investment decision by assessing proposed investment options for raising Dahla Dam for 13.6 m from technical and economic aspects. It is a result of a comprehensive analysis of quantitative and qualitative data, and information collected from secondary and primary sources collected through TRTA field-level investigations (bathymetric survey, May 2018; topographic survey, November 2018; and geotechnical survey, December 2018). In addition, hydrology study utilizing the Soil and Water Assessment Tool (SWAT) for modelling climate change impacts on reservoir’s hydrology and sedimentation; and dam safety analysis including analysis using GeoSlope software were conducted. This report has extended the concept design (September 2018) for Dahla Dam raising to a feasibility design. The project design is based on assessment of the situation, issues and priorities of stakeholders, and careful selection of viable, affordable options, estimating capital and operational costs, for which investment is justified.

4. This report is a further extension of the original feasibility report submitted in February 2019. Some additional details are provided in this report like project scope has been extended to include park and Panel of Expert, the hydrology has been updated as per Ewater input, geotechnical data has been updated after receiving additional investigation, more details are added to various other outputs items as per request of ADB/MEW, comments / reply matrix has been integrated to the report, drawings has been updated with addition of more drawings and

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cost has been updated as well with more refined data from various components. Accordingly, additional Appendices are added to the original report.

B. Approach and Methodology Used in Project Design

5. This project component will contribute to the overall integrated water management investment outcome. Details of the project costs are provided as Appendix 1. Proposed project schedule is provided as Appendix 2. The output plots of Ewater updated hydrology are presented as Appendix 3. Revised Feasibility Drawings are presented as Appendix 4. Revised Feasibility Hydraulics Report is presented as Appendix 5. Revised Feasibility Structural Report is presented as Appendix 6. Documents received for study are presented as Appendix 7.

6. The design approach for the raising Dahla Dam and six saddle dams is to support the policy goals of government in improving management and efficient use of water resources, climate resilience, and to provide electricity to partially overcome the present shortage of power supply to the South East Power System (SEPS), which is currently obliged to carry out large-scale rotating load shedding. The component design approach is also aligned with the ADB’s country program priorities.

7. The design reflects and encompasses the priorities of MEW as expressed in the Afghanistan National Development Strategy (2007). The design is aligned with the Water Law (2009),4 which formalized the adoption of integrated water resources management principles within national water sector policies and sector strategies of MEW, MAIL, Ministry of Rural Rehabilitation and Development (MRRD), Ministry of Urban Development and Housing, Ministry of Mines, Ministry of Public Health, and the National Environmental Protection Agency (NEPA) which all have direct mandates in the water sector. The design also reflects the priorities of ASBA.

8. The feasibility design followed a sequence of activities:

Review of the available project information, drawings and reports; Performance of the failure mode analysis for the dam site; Conduct of bathymetric survey to estimate sedimentation of the reservoir site and

understand the hydrology of the reservoir; Preparation of the dam optimization and concept design report covering analysis

of various dam raise options; Conduct of the geotechnical investigation for the project site; Conduct of the topographic survey for the project site; Preparation of the revised hydrology report based on new survey results and

estimates of the storage volume for the reservoir for various dam raise options; Preparation of the revised feasibility report and drawings based on new survey

results and corrections in estimates of the storage volume for the reservoir for various dam raise options;

Preparation of the hydraulics report with details of spillways and assessment of existing intake and outlet structures.

9. Dahla Dam was constructed in 1952 to store 478 million m3 of water mainly for irrigation and flood control purposes, with the anticipated extension of the Arghandab reservoir water use for hydropower generation not being implemented. During 66 years of dam operation, the Arghandab reservoir has lost about 40% of water storage due to sedimentation and is currently estimated to store about 288 million m3 of water at Full Supply Level (FSL) of 1,135.4 m (WGS84

4 Water Law. Official Gazette. Ministry of Justice. Islamic Republic of Afghanistan. Issue # 980. 26 April 2009.

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elevation).5 The discharge data downstream of the spillway for the project is available from 1948 to 1980. With the annual average reservoir inflows estimated at 1,380 million m3 and outflows from the spillway estimated at around 1,100 million m3 under no-supply from irrigation outlets, dam appears to work like a run-of-the-river project.

10. USGS’ study at Qala-Bast / Lashkar Gah, about 179 km downstream of Dahla Dam, estimated mean inflows as 888 million m3.6 The inflow years were taken from 1948 to 1980. This inflow record includes five years from 1948 to 1952 before construction and subsequent 28 years from 1953 to 1980 post construction of Dahla reservoir. These inflows excluded used irrigation water in agriculture lands below Dahla Dam and also subsequently excludes storage in the reservoir and other usage below dam. It should be noted that Dahla reservoir storage was initially 478 million m3 and within 28 years should have reduced at 2.78 million m3 per year i.e. about 400 million m3. This is consistent with mean average inflows to Arghandab river as 1,380 million m3 per year. The proposed additional storage of 500 million m3 is thus consistent with inflows and would help regularize the outflows to Arghandab River during summer months.

11. The topographic survey conducted during TRTA has applied significant corrections in various structural elevations. There were critical elevation errors in the previous elevation measurement of the outlet structures. The noted error was 10.883 m for penstocks and irrigation outlets. The WGS 84 elevation for the penstock was reported as 1101.15 m whereas actual WGS84 elevation was measured as 1090.27 m. Therefore, these structures are located deeper than reported. This means that the discharges estimated and released from the irrigation outlets were in gross error and in reality, higher than reported and hence underestimated. This means that over the year, irrigation supplies from the dam were higher as compared to the reported discharge by the Arghandab Sub-basin Authority (ASBA). This will significantly affect the hydrology of the dam. It is recommended that discharges from the irrigation outlet be re-calibrated based on this correction. The charts / graphs used to estimate flows from both irrigation outlet and penstock need to be updated during next design stage. Once corrected the outflows from the dam should be consistent with above USGS study and remove the concern about water availability for the proposed dam raise.

12. The recommended dam raise of 13.6 m adds an additional 500 million m3 to Dahla reservoir with a water head of 58.75 at FSL giving a hydropower potential of 28.5 MW and allows for a buffer storage to maximize storage for later release as per downstream requirement. Recent topographic survey has applied significant corrections in various structures elevations. The proposed raise, after corrections in structures elevation, will add a water head of 26.08 m. A total water head for hydropower production under reservoir FSL will then be 58.75 m. This is positive for the region considering availability of such water head for power generation. The inflows to Dahla reservoir are mainly from snowmelt in Hindukush mountains. These inflows are typically high and for short duration spread over typically three to four months. Reservoir’s additional buffer capacity will maximize storage during these high inflow months and above average years. Over recent years, increased reliance in Kandahar region has been placed on groundwater to supplement surface water irrigation. This has resulted in a major decline in the water table, which if unchecked will limit the potential for groundwater irrigation in the medium term. The dam raise should maximize storage and minimize spills from spillways to minimize groundwater irrigation, except when agreed water allocations cannot be delivered. The frequency of high and lows for

5 World Geodetic System 1984: WGS84 is an Earth-centered, Earth-fixed terrestrial reference system and geodetic

datum. WGS84 is based on a consistent set of constants and model parameters that describe the Earth's size, shape, and gravity and geomagnetic fields.

6 Williams-Sether, Tara (2008) Streamflow Characteristics of Streams in the Helmand Basin, Afghanistan: U.S. Geological Survey Data Series page 190 to 194.

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the inflow to Dahla reservoirs is likely to increase over time, therefore, a 13.6 m raise will maximize benefits for the region and offer better climatic proofing as compared to a lesser raise.

13. Along with Kajaki with an installed capacity of 51.5 MW, Dahla hydropower station will significantly contribute in the positive development of the region. This should give significant boost to the economic activities in the Kandahar region. Time for pay back of hydropower comprising 3 x 9.5 MW Francis / Kaplan is estimated as only 1.69 year of operation, as detailed in Component 4 feasibility study.

14. Based on the study, dam raising option of 13.6 m is technically feasible. The design is a robust and economical design; and has been used in Australia on various dams. Due to climate change, wet seasons and dry seasons are likely to increase. A 13.6 m raise offers better flexibility for demand and supply from Dahla Dam, with minimum spill under average years, and is therefore recommended.

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II. COMPONENT 1 - EXISTING SITUATION

A. Overview of the Component 1

15. Component 1: Raising Dahla Dam and six saddle dams aims at increasing water storage capacity. This Investment in the Dahla Dam raise, with the accompanying investment in improving Arghandab catchment water management, reservoir multisector water use, and Dahla Dam operation, has been identified as a long-term solution to provide more consistent water supply for municipal water, irrigation, hydropower and environmental flows.

16. This report provides an evidence-based platform for making an investment decision by assessing proposed investment options for raising Dahla Dam for 13.6 m from technical and economic aspects. This feasibility design will be further developed during next detailed design phase of the project before actual construction.

B. Key Issues

17. Dahla Dam was constructed in 1952 to store 478 million m3 of water mainly for irrigation and flood control purposes, with the anticipated extension of the Arghandab reservoir water use for hydropower generation not being implemented. During 66 years of dam operation, the Arghandab reservoir has lost about 40% of water storage due to sedimentation and is currently estimated to store about 288 million m3 of water at FSL of 1,135.4 m (WGS84 elevation).7 The discharge data downstream of the spillway for the project is only available from 1948 to 1980. With the annual average reservoir inflows estimated at 1,380 million m3 and outflows from the spillway estimated at around 1,100 million m3 under no-supply from irrigation outlets, dam appears to work like a run-of-the-river project. A study from CIDA (2012) concluded that spills from spillway under existing condition are 726 million m3.

18. TRTA topographic survey corrected elevations of the structures resulting in significant opportunity to generate untapped hydropower of the dam which is critical for the region. The revised total volume of water in the Dahla reservoir as a function of the water level in the reservoir has been considered in this report. This and the revised differences between the elevation of water level in the reservoir and the elevations of the center lines of the connections to the power stations have changed the calculations of power and electrical energy in a positive direction. The calculations of power and electrical energy have been carried out on the basis of a best estimate concerning the required irrigation and environmental flows. With proposed dam raised to elevation 1154 m for dam crest, and full supply level to 1149.0 m a head of over 58 m will provide a significant opportunity to use Dahla reservoir for hydropower.

19. A 13.6 m raise at Dahla will add an additional storage of 500 million m3 to the existing 288 million m3 reservoir with a head of 58.75 m at FSL and will be a significant opportunity to generate and add electricity to the grid. Considering a sedimentation rate of 2.7 million m3/year, Dahla reservoir once raised should have a life of over 200 years. Installation of a seasonal flow forecasting system should help to further optimize the operation of Dahla Dam. Therefore, a 13.6 m dam raise and installation of a hydropower at Dahla is highly recommended and should give significant boost to the economic activities in the region.

7 World Geodetic System 1984: WGS84 is an Earth-centered, Earth-fixed terrestrial reference system and geodetic

datum. WGS84 is based on a consistent set of constants and model parameters that describe the Earth's size, shape, and gravity and geomagnetic fields.

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20. For analysis and establishing operation scenarios, the reservoir storage capacity for different elevation levels has been assessed through a bathymetric and topographic survey and evaluation of the reservoir model for depth storage in relation to the potential buffering volume.

C. Existing Dahla Dam Infrastructure

21. Construction of the dam was contracted out to Morrison-Knudsen Afghanistan, Inc. under the ‘second contract’. The dam, constructed 18 miles north of Kandahar, was completed on schedule and at a saving of some $ 2.5 million over the original estimate. The dam was dedicated on 27 December 1952. The final design catered for a storage capacity of 398,000 acre feet (491 million m³), and more thorough surveying along the Arghandab resulted in the estimate of irrigable land increasing from 120,000 to 156,000 acres, implying the potential of bringing new land under irrigation, increasing it from 20,000 to 56,000 acres.

22. Dahla Dam is located approximately 35 km northeast of Kandahar City on the Arghandab River and is operated by the Helmand and Arghandab Valley Authority (HAVA). Dahla Dam was designed by International Engineering Company, Inc. and constructed by Morrison-Knudsen, Afghanistan, Inc for the Government of Afghanistan as part of the larger HAVA project. Dam construction began in 1950, and the dam has been in operation since 1952. The Arghandab reservoir was intended to supply irrigation water to the Arghandab Valley.8 More details on the existing Dahla Dam infrastructure are provided in the Chapter II: Review of Historical Dahla Dam Design. This design review is critical to understand the 1952 design and subsequent dam safety consideration for future upgrades.

8 Morrison-Knudsen Afghanistan, Inc. 1956. Final Design Report on Kajakai Dam, Arghandab Dam and Boghra Canal

Projects. International Engineering Company.

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Figure 1. Dahla Dam: Main Embankment, Saddle Dams 1-6, and Spillways 1 and 2

Source: USACE, TAM Construction Management Plan Concept of Operation, 30 April 2014, Dahla Dam Improvements Project

D. Principal Project Data

23. Table 1 presents principal project data for the 1952 design and proposed 13.6 m spillway raise.

Table 1. Principal Project Data Description 1952 design 13.6 m raise

1. Dam type Clay core rockfill embankment / zoned earth fill

2. Storage capacity (million m3) 478 a 782

3. Catchment area (km²) 12,925

4. Reservoir area (km²)

4.1 At FSL 29.54 45.81

4.2 At PMF 33.00 50.05

4.3 At Dam Crest Flood (DCF) 35.05 52.71

5. Bottom of conservation storage (WGS 84) (m) 1,095.4

6. Dam height above deepest foundation (m)

6.1 Main dam 60 73

6.2 Saddle Dam 6 20 33

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6.3 Saddle Dams 1 to 5 5-15 18-29

7. Dam crest elevation (WGS 84) (m) 1,140.9 1,154

8. Dam crest length (m)

9.1 Main dam 535 755

9.2 Saddle Dam 6 and extension 180 510

9.3 Saddle Dams 1 to 5 and extension 1,515 1995

9. Dam crest width (m)

9.1 Main dam 8.0 8.0

9.2 Saddle Dam 6 and extension 6.4 8.0

9.3 Saddle dam 1 to 5 and extension 6.4 8.0

9.4 Saddle Dam 6 extension with Spillway 1 12.0




10. Free board (m)

10.1 At spillway level 5.0 5.0

11. Spillway crest elevation (WGS 84) m 1,135.4 1,149

12. Spillway type

12.1 Spillway 1

Length

Curved weir

260

Ogee

220

12.2 Spillway 2

Length

S curve weir

100

Ogee/Partial combination of gated and ogee

120

13. Discharge capacity at PMF (m3/s)

13.1 Spillway 1 2,600 2301

13.2 Spillway 2 1,160 1255.2

13.3 Total discharge capacity 3,760 3,556

14. Inlet / outlet / diversion tunnel * To be inspected / reviewed in detailed design if unlined portion should be concrete lined.

14.1 Total length (m) 254 254

14.2 Concrete lined length 4.6 m diameter 70 254

14.3 Unlined rock – 5.4 m diameter 184 -

15. Trash rack To be reviewed in detailed design

15.1 Type

Inclined trash rack at the intake supported on the rock slope at an angle of about 45 degrees.

15.2 Openings (m) Two 2.6 m x 12.37 m

15.3 Velocity (m/s) at maximum head 1110 m < 0.92 To be reviewed in detailed design

15.4 Top operating level (m) at guides 1136.5 1136.5

15.5 Bottom operating head level (m) for unwatering the tunnel using bulk head

1113.4 1113.4

15.6 Operational requirements (no permanent hoisting required)

10 tons truck mounted crane

To be reviewed in detailed design

16. Intake Tower To be reviewed in detailed design

16.1 Type A concrete lined 5.2 m diameter, 0.3 m thick

lined shaft through rock above the tunnel,

daylighting at El 1,123.4 m. Above this level

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the structure was extended through the

reservoir as a closed reinforced concrete

tower.

16.2 Openings (m) 3.4 m x 4.6 m

16.3 Tower wall thickness (m) 0.4 below 1136.4 m

0.3 below 1140.4 m


16.4 Gate maintenance deck level (m) 1144.4 1158

16.5 Gate type Fixed wheel To be reviewed in detailed design

16.6 Gate weight (t) 17.690 To be reviewed in detailed design

16.7 Hoist rated capacity (t) 64.397 To be reviewed in detailed design

16.8 Hoist lifting speed (m/s) 0.61 To be reviewed in detailed design

16.9 Operating arrangement

Normal operation

Emergency operation

15.2 metric horsepower motor

A hoist arrangement for lowering from a control panel on the tower operating deck



16.10 Access to tower Structural steel foot bridge with a 16.307

m span.

Structural Steel foot bridge over pile

foundations. To be designed during detailed design

17. Irrigation outlet * To be reviewed in detailed design

17.1 Diameter (m) b 1.22 1.68

17.2 Elevation (m) b - 1092.52

17.3 Flow (m³/s) at maximum head c 52 116

17.4 Flow (106 x m³/day) at maximum head 4.493 10.02

17.5 Type Howell Bunger valve Howell Bunger valve

17.6 Operating arrangements 7.6 hp electric motor As per new facility

17.7 Operation during hydropower generation Limited requirements as most demand should be met through flows from turbine discharges

18. Penstock outlet for hydropower

18.1 Diameter (m) 4.6 to 2.85

18.2 Centerline elevation (m) - 1090.3

18.3 Maximum head (m) at FSL 45.27 57.3

18.4 Flow (m³/s) at maximum head 110

18.5 Flow (106 x m³/day) at maximum head 9.5

19. Total combined (16+17) maximum discharge at maximum head (106 x m³/day)

19.5

Note: a The estimated present (2018) storage capacity is 288 million m3. TRTA estimates. b New Irrigation Outlets were installed in 2014 replacing 48-inch pipes (1.22 m) with 66-inch pipes (1.68 m). c Total from both gate valves. Should be re-assessed and calibrated during model studies for various heads. Source: Morrison-Knudsen Afghanistan, Inc. 1956. Final Design Report on Kajakai Dam, Arghandab Dam and Boghra Canal Projects. International Engineering Company; and TRTA Consultants. 2018. * Tetra Tech for USACE, Dahla_Dam_Hydraulics_App.pdf. 2011.

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E. Project Infrastructure

24. The main dam embankment is 60 m high from the deepest foundation, has a WGS84 crest elevation of 1140.9 m with a crest length of approximately 540 m. The reservoir FSL is 1,135.4 m, with a surface area of 29.4 km2 and a storage capacity of approximately 478 million m3 at FSL. The project includes six saddle dams along the reservoir perimeter. Five of the saddle dams have a maximum height of 15 m and an aggregate length of 1,515 m. The sixth saddle dam has a maximum height of 20 m and a crest length of 145 m. All together the project dam length for 1952 design is 2.2 km.

25. There are two open channel spillways: Spillway 1 is located 1.5 km between Saddle Dams 6 and 5, and Spillway 2 is 2.2 km, northwest of the main embankment between Saddle Dams 3 and 4. Each spillway has an ungated concrete weir. Spillway no. 1 is about 240 meters long, and Spillway 2 is 100 m long. Both spillways discharge in to existing channels that enter the river downstream of the dam.

26. The Route Bear Highway passes the project area along the right abutment of saddle dam no. 1. The highway was realigned at limited reaches for an 8 m raise of the Dahla Dam in 2014.

27. The outlet works consists one 4.6 m diameter tunnel, an inlet portal and trash rack located at the main dam right abutment, an octagonal concrete intake tower located 49 m upstream of the dam axis, and an outlet control valve house, located at the right abutment at the downstream toe of the embankment. Two 122 cm diameter pipes branch from the tunnel into the valve house to supply the irrigation outlets, which are controlled by Howell Bunger valves.

F. 1952 Assessments and Studies

1. Geological and Geotechnical Stability Review

28. The dam site is located in an approximately 360 m wide valley of the Arghandab River. The natural streambed occupies the left side to the valley. The right abutment slopes upward at an angle of about 40 degrees with the horizontal. The left abutment slopes at about 30 degrees. At least six saddle dams exist in the range which forms the southwest rim of the Arghandab reservoir namely saddles 6 to 1, while moving from the right abutment.9

29. Subsurface explorations at the dam site showed the presence of a coarse-grained granite formation intruding into metamorphic rock beyond the left abutment. The rock was friable and deeply weathered at the left abutment, and blocky and irregularly decomposed on the right abutment. Field investigations by Morrison-Knudsen Afghanistan, Inc. in 1950 showed a gradual transition from completely weathered rock at the surface to sound rock at a considerable depth. No well-defined contact between the two rock conditions was evident. The rock was found to be jointed in many directions, the dominant patterns, including shear zones, being in N-S, E-W, and NW-SE directions. The dips ranged from largely vertical to around 45 degrees. Basaltic dikes which were found to be present on both sides were also largely vertical and correlated with the NW-SE system of joints. The valley floor was overlain by alluvium consisting generally of a layer of silt, about 1 m thick, overlying sand, gravels and cobbles, and extending to bedrock at a maximum depth of about 12 m.

30. For the 1952 design, laboratory testing was completed on the shearing resistance of impervious materials in triaxial tests. Subsequent stability analyses indicated that slopes of 2.5:1 upstream and 2:1 downstream were adequate and the section was revised accordingly. An access



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road to the top of the dam was provided by construction of an inclined berm on the downstream face.

2. Seismic Review

31. The site is in a region which had not been exposed to recent seismic disturbances. The nearest active area is at Quetta in Pakistan, 320 km from the dam site. The structures were designed in 1952 to resist inertia forces produced by a ground wave-acceleration equivalent to 0.05 gravity.

3. Main Dam Left Abutment Shear Zone

32. In the 1952 design, the presence was noted of a 1.22 m to 6.1 m wide curving shear zone/groins behind the promontory which forms the left abutment. This zone, unless sealed, would permit seepage in a direction parallel to the river. At the geologist's recommendation the axis of the dam was moved about 30 m upstream so that the impervious core of the dam would blanket the shear zone.

4. Foundation Treatment / Grouting

33. The test pits, completed in 1952, were carried only to shallow depths limited by the groundwater table. The material removed from these pits was primarily silt and would have been unsuitable for the dam unless embankment slopes were flattened appreciably. The depth of foundation deposits was found, by diamond drill holes, to average 10 m to 12 m. Preliminary studies indicated that it would be more economical to strip the overburden from the entire foundation area than to flatten the embankment slopes which would increase the embankment volume and the length of the outlets.

34. Subsequent foundation investigations revealed that the silty material was a relatively shallow deposit overlying clean sand and gravel. Since sand and gravel are structurally adequate for a dam of the proposed cross-section, it was decided to leave this material in place, except under the impervious core.

35. A trench under the entire foundation area was excavated through sand and gravel to sound rock. It was backfilled with rolled earth. A grout curtain was placed along the centerline of the cutoff trench, through primary grout holes at about 20 m centers and approximately 20 m in depth near the base of the dam. Secondary holes, approximately midway between the primary holes, would extend 10 m to 20 m below the surface as required.

5. Borrow Area Materials

36. Preliminary field investigations, prior to the 1952 dam construction, showed that materials suitable for construction of an earth fill dam, and in suitable quantities, were available near the main dam site. The available materials were generally of two types which were suitable together for a zoned embankment: an impervious silty clay and pervious sand and gravel.

37. It was estimated that five borrow areas would furnish ample materials for embankment construction: 2 upstream; 2 on the right bank; and one on the downstream right bank.

38. As the upstream borrow areas would be submerged during the second stage of construction, 3 additional borrow areas, about 1.5 km and 2.5 km on the downstream right bank were explored and found to contain suitable materials. Another borrow area was found about 4 km downstream from the main dam to furnish material for saddle dam construction. Rockfill for dike no. 6 was to be obtained from spillway excavation.

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6. Triaxial Testing on Material

39. Triaxial shear tests were made to determine the shearing resistance of the materials for stability analyses of the embankment slopes. Three samples of typical borrow area materials were shipped to a laboratory in the United States. Two of these samples were impervious silty clay materials, and the third was a somewhat coarser material classified as semi-pervious. A description of the testing procedures and a summary of test results appear in a report by Abbot A. Hanks, Inc. Consolidated quick triaxial shear tests were performed on saturated specimens of compacted materials. A discussion of the various types of triaxial testing procedures and their application appear in a special report by International Engineering Company, Inc.10

7. Stability Analysis

40. Studies of the stability of the embankment slopes were made by the sliding-block or wedge-method of analysis in which plane surfaces of failure are assumed. For purpose of analysis, the assumed shearing resistances of impervious and semi-pervious materials were the minimum values obtained from triaxial shear tests.

41. A conservative figure of 34 degrees was assumed for the angle of internal friction of shell material based on large-scale tests on similar materials which have been performed in laboratories of United States government agencies.

42. Internal pore pressures in the impervious core were assumed as equal to 100% of the maximum reservoir head. Since internal pore pressures of this magnitude are extremely unlikely, computed factors of safety only slightly in excess of unity were considered ample.

8. Spillway Foundations

43. For Spillway 1, granitic rock in the spillway ridge cut area was deeply weathered. Although the cut for was 15 m to 25 m deep, the rock is generally soft at the bottom. For spillway 2, the cut for is shallower and that rock is also generally weathered and seamy. To prevent erosion, concrete crest structures were therefore provided for both spillways.

44. At Spillway 1, the structure consisted of a low concrete overflow weir, 1.5 m high at maximum section. A cutoff extended into rock a minimum of 0.6 m. The weir was reinforced with temperature steel and secured to rock by two lines of 1 m long steel dowels spaced at 2 m centers along both lines. The grouted dowels extended about 0.5 m below the bottom of the cutoff.

45. A downstream apron of hand-placed stone blocks was designed to have a minimum weight of 91 kg. The apron had a variable length from 3 m to 6 m and terminated at a concrete cutoff wall extending a minimum of 1 m into soft rock and 0.6 m into sound rock. When fresh hard rock was exposed, the stone paving would be omitted. The entire foundation was to be grouted under low pressure through a series of holes downstream from the weir and spaced about 5 m to 6 m apart.

46. At Spillway 1, the structure consisted of a 0.6 m high weir section with a concrete apron extending a minimum of 7 m downstream from the weir. There was a 0.6 m deep cutoff wall at the upstream end of the structure, and a 1 m deep wall at the downstream end. An under drain of stone masonry was placed beneath the apron. The structure was reinforced with temperature steel and anchored to rock below the upstream cutoff. Transverse joints were located at 9.3 m intervals along the crest. The entire foundation would be grouted at low pressure along a line of grout holes



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spaced at intervals of about 5 m. A hand-laced stone apron would continue below the concrete apron for a maximum distance of 15 m.

9. Spillway Hydraulic Modelling

47. For the 1952 design, reservoir routing initially estimated 3,398 m3/s outflows from the PMF for a combination of gated and fuse plug option. Scale models of Spillways 1 and 2 were constructed in the field laboratories of Morrison-Knudsen Afghanistan Inc. Both quantitative and qualitative tests were performed to determine hydraulic characteristics of the crest structures and outlet channels. From tests of the flow pattern for both spillways, the configuration of the crest and channel was modified to produce a streamlined flow. Design changes which resulted from the tests decreased rock excavation by about 122,000 m3, but also increased the volume of rock and concrete masonry by about 1,400 m3.

48. The dam was raised by 2 m to allow for additional free board for a fuse plug embankment while keeping spillways at 1,110 m Construction Datum Elevation. There is no discussion which embankment was to be used as a fuse plug. Such embankments need careful design and will have to be identified. Saddle embankment will have lower elevation than the main dam elevation of 1,115.5 m construction elevation or 1140.9 m WGS elevation.

G. Dam Safety

49. Since the completion of construction and the subsequent operation of Dahla Dam, the following observations have been made:

Dam: Performance has been generally satisfactory. As the reservoir was filled, minor seepage occurred at the downstream toe. The effluent water was observed to be clear. This indicated that no piping was taking place. It was decided to install a collector drain designed as an inverted filter to collect seepage. With the reservoir at El 1,110 m the observed quantity of seepage was 0.0085 m3/s.

Spillway: First discharge over the Arghandab spillway occurred on 26 May 1954. Discharge reached a peak of 269 m3/s on 30 March 1954, with the reservoir at El 1,110.66 m. Erosion occurred in the disintegrated granite to depths from 1.83 m to 2.44 m in the lower reaches of the channel and to depths up to 3.66 m in the upper reaches. Some erosion was anticipated, and its effect was given consideration during the design. Rock riprap below the spillway weir was relatively undisturbed. In a few spots ravelling took place.

Outlet works: The outlet regulating valves have been in constant service since February 1952. They have been operated under varying conditions head and openings. In March and April of 1954, the valves were discharging continuously in a full-open position, with reservoir water service above the spillway crest level. The maximum discharge under these conditions was 52.6 m3/s. Performance of the valves has been satisfactory in all respects. The fixed-wheel intake gate and ring-follower gates have been tested periodically after installation and have functioned as expected.

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III. PROBLEM ANALYSIS

A. The Core Problem

50. Dahla Dam was constructed in 1952 to store 478 million m3 of water mainly for irrigation and flood control purposes, with the anticipated extension of the Arghandab reservoir water use for hydropower generation not being implemented. During 66 years of dam operation, the Arghandab reservoir has lost about 40% of water storage due to sedimentation and is currently estimated to store about 288 million m3 of water at FSL of 1,135.4 m (WGS84 elevation). The discharge data downstream of the spillway for the project is only available from 1948 to 1980. With the annual average reservoir inflows estimated at 1,380 million m3 and outflows from the spillway estimated at around 1,100 million m3 under no-supply from irrigation outlets, dam appears to work like a run-of-the-river project. A study from CIDA (2012) also concluded that under existing condition spills from spillway were 726 million m3.

51. USGS’ study at Qala-Bast / Lashkar Gah, about 179 km downstream of Dahla Dam, estimated mean inflows as 888 million m3. The inflow years were taken from 1948 to 1980. This inflow record includes five years from 1948 to 1952 before construction and subsequent 28 years from 1953 to 1980 post construction of Dahla reservoir. These inflows excluded used irrigation water in agriculture lands below Dahla Dam and also subsequently excludes storage in the reservoir and other usage below dam. It should be noted that Dahla reservoir storage was initially 478 million m3 and within 28 years should have reduced at 2.78 million m3 per year i.e. about 400 million m3. This is consistent with mean average inflows to Arghandab river as 1,380 million m3 per year. The proposed additional storage of 500 million m3 is thus consistent with inflows and would help regularize the outflows to Arghandab River during summer months.

52. The water release schedule provided to the TRTA irrigation consultant by ASBA in Kandahar shown in Table 2. The schedule does not align with the volume of storage and the volume required cannot be supplied throughout the season, even in wet years, as storage is limited to 288 million m3 approximately at present.

Table 2. ASBA Release Schedule

Period Date / start Date / end Period

(days)

Discharge b

(m³/s)

Total

discharge (m3)

A1 - spring fill - crop

establishment

01 Hamal 01 Jawza 62 75 401,760,000 a

21-Mar-18 22-May-18

A2 - summer

growth/flowering

01 Jawza 01 Sunbula 93 50 401,760,000

22-May-18 23-Aug-18

A3 winter wheat

planting/crop ripening

01 Sunbula 15 Mizan 46 35 139,104,000

23-Aug-18 8-Oct-18

Winter slumber 10 Qaws 10 Jadi

30 50 129,600,000 1-Dec-18 31-Dec-18

Total volume released if dam flow as schedule all season 1,072,224,000

Volume of storage after leaving sump in reservoir 200,000,000 Source: ASBA, 2018 Notes: a Spillway discharge if dam is full is critical.

b These discharges will be validated through a hydraulic model study after significant correction in structures elevations was applied as per survey performed by the TRTA. This will provide corrected outflows from the reservoir.

53. The topographic survey conducted during TRTA has applied significant corrections in various structural elevations. There were critical elevation errors in the previous elevation measurement of the outlet structures. The noted error was 10.883 m for penstocks and irrigation

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outlets. The WGS 84 elevation for the penstock was reported as 1101.15 m whereas actual WGS84 elevation was measured as 1090.267 m. Therefore, these structures are located deeper than reported. This means that the discharges estimated and released from the irrigation outlets were in gross error and in reality, higher than reported and hence underestimated. This means that over the year, irrigation supplies from the dam were higher as compared to the reported discharge by the Arghandab Sub-basin Authority (ASBA). This will significantly affect the hydrology of the dam. It is recommended that discharges from the irrigation outlet be re-calibrated based on this correction. The charts / graphs used to estimate flows from both irrigation outlet and penstock need to be updated during next design stage. Once corrected the outflows from the dam should be consistent with above USGS study and remove the concern about water availability for the proposed dam raise.

54. Over recent years, increased reliance in Kandahar region has been placed on groundwater to supplement surface water irrigation. This has resulted in a major decline in the water table, which if unchecked will limit the potential for groundwater irrigation in the medium term. The proposed dam raise will maximize storage and minimize spills from spillways during average, above average and wet year high inflows to minimize groundwater irrigation, except when agreed water allocations cannot be delivered. The buffering effect of the reservoir is a significant factor in optimizing water availability and respectively balancing flows between upstream inflow and downstream demands, enabling the operators to distribute flows over time to better respond to downstream demands. Reservoir’s additional buffer capacity will maximize storage during high inflow months. The frequency of high and lows is likely to increase over time. A multisector water allocation options study intends to provide guidance to ASBA in drawing up regulations to manage the water received by the dam and distribute it among the various users and uses.

55. The combination storage and hydropower dam was one of the investment projects on the Government of Afghanistan’s own list of investment projects.11 Its water releases would support double cropping on the 100,000 acres of agriculture land in the Kandahar region already being irrigated from the Arghandab River during the spring flow season, and particularly the economically important fruit-growing region close to Kandahar City. Preliminary design reported a storage capacity of 315,000 acre feet (389 million m³), which would be adequate to ensure a full irrigation service of 4.3 acre feet (per acre) to 120,000 acres, thus improving irrigation water supply to the existing area and also allowing for an expansion with 20,000 acres.

B. Summary of Key Issues of Infrastructure in Component 1

56. The feasibility design considered following key issues for the Component 1 infrastructure:

57. Bathymetric survey: A bathymetric survey was required to estimate the sedimentation in the reservoir. There were challenges of accuracy of the survey due to limited access to the site and available 30 m contours for estimation of the reservoir volume. This bathymetric survey provided baseline for the hydrological analysis of the dam site.

58. Additional geotechnical survey: Additional geotechnical investigations were critical to perform along various existing structures to make informed decision on the dam feasibility design. As the reservoir area would increase from 29.54 to 45.81 km2, significant material from the existing and proposed raised reservoir should be available. The geotechnical investigation has to validate that quantity of earth fill along the Route Bearer Highway for the dam construction be available.

59. The topographic survey was available only after the additional geotechnical investigation were over. Final setting of the proposed dams and spillway structures will require additional

11 Michel, A.A. (1959:141;152)

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geotechnical investigations and model studies should be performed to finalize the design of the dam extensions and spillway 1 as per feasibility drawings.

60. The feasibility design added corrections in sitting of the new structures: Spillway 1 was relocated to the downstream of the existing spillway to minimize the cost of the new structure using existing natural rock hill abutments. This will require additional investigations along Spillway 1 during detailed design. The investigations should include boreholes along spillway length and boreholes along abutments. Additional geotechnical investigations for the detailed design of the Saddle Dam 6A, main dam left abutment, trash rack structures, intake tower bridge and Route Bearer Highway during / before construction are also proposed.

61. Topographic survey: A topographic survey was critical to make informed decision on the dam design critical for the dam safety. The topo survey had to correct several key elevations based on WGS 84 datum and improve the bathymetric survey. There were several key structures where correct elevations were critical for the success of the project. Like hydropower production depends on the correct elevations of penstock and available head. The survey has to be further used for the resettlement survey of the affected people in the area. The Route Bearer Highway inundation limits were to be corrected based on the new survey.

62. The survey covered the dam and reservoir area, nearby likely resettlements and Route Bearer Highway up to a maximum 1160 m WGS84 datum elevation. A feasibility level /Tender design for the Route Bearer has been prepared. A detailed centerline survey with cross sections at every 25 m will be required before actual works execution. This new survey will form the basis of payment. The survey highlighted significant corrections on several project features and removed oversights that were critical for the successful and cost-effective design and delivery of the project. This included corrections in:

Project benchmarks. This resulted in correction in sitting of the project structures and corrected all structural elevation by applying 1.7 m correction in all levels.

There were critical elevation errors in the sitting of the outlet structures. The error was 10.883 m. These structures are actually deeper than reported. This means that the discharges estimated and released from the irrigation outlets were in gross error and in reality, far more then reported and grossly underestimated. This means that over the year irrigation supplies from the dam are more as compared to the reported discharge by ASBA. This will significantly affect the hydrology of the dam. It is recommended that discharges from the irrigation outlet be re-calibrated based on this correction. The charts / graphs used to estimate flows from both irrigation outlet and penstock need to be updated during next design stage. It is strongly recommended that discharges from the irrigation outlet must be re-estimated based on this correction.

Available storage. The storage available for various raise options were corrected. The concept design storage for 8 m and 12 m dam raise, based on 30 m accuracy bathymetric survey, were subsequently updated to reflect new survey. It was noted that in order to obtain 300 million m3 additional storage, the dam has to be raised for 9.1 m i.e. 1144 m, and in order to obtain 500 million m3 additional storage the dam has to be raised to 13.6 m i.e. 1149 m. It was concluded that the spillways should be raised to 13.6 m to obtain proposed 500 million m3 Storage.

Confirmed availability of additional 10.883+13.60 = 24.483 m head for hydropower generation. The penstock elevation for hydropower generation was in error of 10.883 m and corrected. The proposed raise is 13.6 m. All together this will add total water head of 24.483 m totaling to 58.8 m. This is a very good news for the region considering availability of such water head for power generation.

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Levels of inundated Route Bearer Highway for 8 m raise. The highway for 8 m dam raise was only for 4.6 km out of about 10 km reach which should have been inundated. An error in route elevation of 1.7 m was also corrected. Should the dam be raised for 8 m then this would have resulted in inundation of significant reach of the highway. A revised design for the proposed new alignment for about 10 km reach for proposed raise is in progress.

Supported identification of affected areas at FSL, PMF and Dam Crest Flood (DCF) elevation of 1154 m.

63. Security challenges during surveys. There were significant security challenges involved for the performance of these survey as the area is occupied by anti-government elements.

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IV. RATIONALE

A. Design Considerations and Lessons Learned

64. Design standards: The design proposed is based on international industry standards, data from existing similar projects, lessons learned in similar dam, small and micro hydro projects internationally, data from DABS, ASBA, USACE, data and analysis from TRTA specialists and prior engineering assignments. Technical drawings have been prepared with details at an entry level of feasibility.

65. Lessons learned: An important lesson learned was that an accurate and timely topographic survey was the key to success of any dam and hydropower project. The survey took longer than anticipated due to high security risks in area. A bathymetric survey was performed before the detailed topographic survey, however, bathymetric survey had to rely on 30 m contours and therefore, overestimated the reservoir storage. Data for reservoir was improved based on the topographic survey. Should an accurate survey would have been performed at an early stage, this would have improved the following:

Identification of the project’s existing and future boundary and key infrastructure such as dams, spillways, and roads;

Identification of the project’s existing and future potential for hydropower due to corrected penstock elevations;

Estimation of the existing and future reservoir’s storage for various dam raise options. This is critical to update the hydrology, hydraulics and other potentials like hydropower. An early and accurate availability reduces re-work;

Identification of the limits of the proposed reservoir and likely affected resettlement works;

Corrected sitting of the key items for hydropower generation and sooner identification of key data gaps and oversights in previous designs;

Improved understanding of the project volume estimates which were critical for the hydrology and hydropower and other studies.

66. In addition to the above, the study also highlighted the lack of capacity in the country to perform various surveys. The study highlighted the need to further train the skilled human resources in Afghanistan to assist in future development of similar projects. This should include MEW, ASBA, and DABS.

B. Key Issues and Considerations

67. Dahla Dam was designed in 1952 to store a total of 478 million m3 volume of water mainly for irrigation and flood control purposes. The dam use was expected to extend to generate hydropower, however it has not been used for this purpose thus far. Due to siltation along the Arghandab reservoir in the dam’s 66 years of operations, the reservoir has lost about 40% of its storage. When raised, the Dahla Dam is envisaged to provide water for domestic and municipal water supply, irrigation, hydropower and environmental flows. The demand for urban water supply at present has been estimated as 3 million m3 a month. This demand is projected to increase to 7 million m3 a month by 2050 with growing population of Kandahar City. The environmental and irrigation flows vary from month to month. It is anticipated that irrigation and environmental flows will be used to generate hydropower from the dam when possible.

68. The Dahla Dam raise needs to be optimized to store inflows presently discharged through spillways. There are number of issues to be considered for the dam optimization. These include assessment of inflows for potential storage, inflow months, hydropower potential assessment,

34

availability of required data, understanding downstream demand, consideration of an upstream dam to increase dam life, realignment of the Route Bearer Highway, resettlement needs resulting from the raised Dahla Dam, and the economic benefits and costs of raising the dam.

69. The inflows to Dahla reservoir are mainly from snowmelt in Hindukush mountains. These inflows are typically high and for short duration. The buffering effect of the Arghandab reservoir is therefore, a very significant factor in optimizing water availability and respectively balancing flows between upstream inflow and downstream demands, enabling the operators to distribute flows over time to better respond to downstream demands. For analysis and establishing operation scenarios, the Dahla reservoir storage capacity for different elevation levels were assessed through a bathymetric survey, improved through additional topographic survey and evaluation of the reservoir model for depth storage in relation to considering the potential buffering volume.12 Additional hydrology assessments were made by E-Water Australia. The output plots are shared in the Appendix 3. It is anticipated that additional hydrological studies will be performed during detailed design stage to further develop multi-sector allocation of the water from the dam.

70. Considering the Arghandab reservoir siltation and decreasing storage areas due to siltation, a possible dam upstream like Hasanzay should significantly increase the life of Dahla Dam. However, increased reservoir area and long transmission should also increase the evaporation losses for the two reservoirs. Lake evaporation losses are estimated to be around 1.8 m per year.

71. A combined storage during an average wet year for Dahla Dam with a 13.6 m raise and Hasanzay Dam should store about 1,260 million m3 at one time. Both dams may not fill every year for an average wet year. There will be ongoing supplies from irrigation and hydropower along with water losses. For intermediate years between average and wet years, there will be probability one in every five years that both dam may fill more than 70%. During wet years, with average inflows reaching 2,800 million m3, both reservoirs should fill up to maximum capacity. The likelihood of such events is once in every 10 years. This means limited outflows from Dahla spillways for an average wet year and maximum storage in two reservoirs and a more controlled outflows with likely more consistent supply for the Kandahar City. However, the availability of data has remained a key concern for this assessment. Further details are provided in the subsequent section.

C. Review of Project Hydrology

72. The Helmand River basin is the largest river basin in Afghanistan. It comprises of the southern half of the country, draining waters from the Sia Koh Mountains in Herat Province to the eastern mountains in Gardez Province (currently known as the Paktia Province) and the Parwan Mountains northwest of Kabul, and draining into the unique Sistan depression between Iran and Afghanistan.13 The Helmand River basin is a desert environment with rivers fed by melting snow from the high mountains and infrequent storms. Great fluctuations in streamflow, from flood to drought, can occur annually. Knowledge of the magnitude and time distribution of streamflow is needed to quantify water resources and for water management and environmental planning.14 Figure 2 presents the location of stream gauges highlighted in red. Table 3 presents the list of stream flow gaging stations for Arghandab River.

12 TRTA Consultants. 2018. Hydrology Study Report. 13 Favre, R., and Kamal, G.M. 2004. Watershed Atlas of Afghanistan: Afghanistan Information Management Service.

Kabul, Afghanistan. 183 p. 14 USGS. 2008. Streamflow Characteristics of Streams in Helmand Basin, Afghanistan.

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Figure 2. Location of Stream Gauges

Source: Williams-Sether, Tara. 2008. Streamflow characteristics of streams in the Helmand Basin, Afghanistan, Fact Sheet 2008-3059. U.S. Agency for International Development.

Table 3. List of Streamflow Gaging Stations with Published Streamflow Statistics Map ref.

Afghan ID number

USGS ID number a Station name Remarks

29 4-1.L00-1A 313000064230000 Arghandab River at Qala-i-Bust 175 km D/s of Dahla Dam

30 4-1.L00-3A 313700065340000 Arghandab River near Kandahar 35 km D/s of Dahla Dam

31 4-1.L00-4A 315000065520000 Arghandab River below Arghandab reservoir

3.5 D/s of Dahla Dam

32 4-1.L00-5A 315700066020000 Arghandab River above Arghandab reservoir

44 km U/s of Dahla Dam

33 4-1.L00-6A 321000066270000 Arghandab River at Mizan 50 km U/s of Dahla Dam

34 4-1.L00-9A 330800067280000 Arghandab River at Sang-i-Masha 175 km U/s of Dahla Dam

Source: Morrison-Knudsen Afghanistan, Inc. 1956. Final Design Report on Kajakai Dam, Arghandab Dam and Boghra Canal Projects. International Engineering Company. Note: a United States Geological Service (USGS).

73. From a water resources planning and modelling perspective, the Helmand River basin is best treated in two distinct parts: (i) the upper mountainous catchment areas in which much of the water resource is generated and where traditional irrigation is the main water user; and (ii) the middle and lower catchment areas where there is existing formal and traditional irrigation and resources that can partly be managed through the operation of two large reservoirs (Kajaki Reservoir and Arghandab reservoir).

74. The Dahla reservoir catchment area is 12,925 km2, while the 1952 reservoir area was 29.54 km2. Mean Annual precipitation is estimated to be 158 mm and annual average lake evaporation losses are estimated in the order of 1.8 m per annum.

1. Historical Inflows at Arghandab Reservoir

75. A historical inflow record for Arghandab River 44 km upstream of Dahla Dam is presented in Figure 3. For a 28-year period, between 1952 and 1980, an average reservoir inflow of 1,380

36

million m3 was estimated with peaks over 2,600 million m3 occurring. A 13.6 m dam raise should store about 788 million m3 at one time while outflows from irrigation and hydropower outlets may continue. There could be limited outflows through the spillways under average years. However, for intermediate and wet years, there should be flows from the spillways. A weather forecasting system is thus critical for the reservoir catchment area.

76. In 1939, historical flood peaks of 1,200 m3/s in 1939 were recorded. No flow record of the 1885 flood was found for the Arghandab River that caused significant damage in the Helmand region.15 A typical contribution of the Arghandab River as compared to Kajaki River is considered as 17%, which means if Kajaki River flows are 100% then flows of the Arghandab River are 17%.16 Based on those figures, a flood over 19,624 m3/s at Kajaki River should equate to 3,274 m3/s at Arghandab River. Similarly, high floods were reported in 1990 that caused significant damage to the area. However, no discharge was recorded. There were no dam safety risks reported and spillways successfully passed that flood.

77. USGS’ study at Qala-Bast / Lashkar Gah, about 179 km downstream of Dahla Dam, estimated mean inflows as 888 million m3.17 The inflow years were taken from 1948 to 1980. This inflow record includes five years from 1948 to 1952 before construction and subsequent 28 years from 1953 to 1980 post construction of Dahla reservoir. These inflows excluded used irrigation water in agriculture lands below Dahla Dam and also subsequently excludes storage in the reservoir and other usage below dam. It should be noted that Dahla reservoir storage was initially 478 million m3 and within 28 years should have reduced at 2.78 million m3 per year i.e. about 400 million m3. This is consistent with mean average inflows to Arghandab River as 1,380 million m3

per year.

15 USGS. 2006. Scientific Investigation Report 2006-5182. 16 Delft Hydraulics and the Water Research Institute. 2005. Integrated Water Resources Management for the Sistan

Closed Inland Delta, Iran. 17 Source: Williams-Sether, Tara (2008) Streamflow Characteristics of Streams in the Helmand Basin, Afghanistan: U.S.

Geological Survey Data Series page 190 to 194

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Figure 3. Historical Inflow Record for Arghandab River During 1948–1980

Note: This data was recorded 44 km upstream of Dahla Dam. Source: Williams-Sether, Tara. 2008. Streamflow characteristics of streams in the Helmand Basin, Afghanistan, Fact Sheet 2008-3059. U.S. Agency for International Development.

2. Additional Hydrological Studies performed by Ewater Australia

78. It is envisaged that all future hydrological assessments will be based on only model results of Ewater. Ewater is an Australian government owned company undertaking inflow modelling for all Afghan basins. Inflows to Dahla basin are accordingly updated based on this study. The study updates inflows, rain, evaporation, sedimentation, urban, environmental, irrigation and hydropower requirements and runs model from 2023 to 2050 under dries, average and wet years. These will be replaced by eWater' s prediction of inflow, based on satellite image interpretation plus ground truthing.

79. The study provides estimated 10%, 50% and 90% wet year data. Other years interpolated (apart from the 0% and 100% years). The baseline is an average of data from 2002 to 2016, assumed to equate to 2009. It can be used to model any year up to 2050.

80. The results and assumptions are presented in Appendix 3.

Inflow are estimated for various conditions. Driest year assumed to be 74% of 10% year. Wettest year assumed to be 113% of 90% year. The study concludes that English months do not exactly coincide with Afghan months but include > 20 days of the Afghan month.

Rainfall on dam plus runoff from immediate all catchments are estimated (i.e. which enters the reservoir, not the Arghandab river only). Thus, the estimated runoff from catchment will need to be added to the reading from the new gauge to estimate total water inflow. The rainfall is used to estimate the rainfall on the dam and runoff from the catchment at different monthly rainfall amounts.

38

Evaporation losses, sedimentation was estimated based on storage. Sedimentation losses were estimated based on inflow. Estimated population of Kandahar and Arghandab villages has also been updated

from 2018 to 2050. Environmental releases are estimated based on inflows and outflows. These

releases are additional to spills, though if the spill exceeds the planned release, there would be no further planned releases in that month.

Irrigation efficiency with and without project is estimated at different inflows. Finally, MSWAT Model assess overall project performance under various

assumptions. However, this has been further discussed in TRTA MSWA report. It is estimated that this will be further developed during detailed stage.

3. Review of Availability of Water for Storage

81. The average year annual inflow to the reservoir based on 1948 to 1980 inflow record should be 1,380 million m3. The leftover storage is 288 million m3, which equals only 20% of the average annual inflows. The reservoir outflows from the spillway under the condition of no-supply from the irrigation outlets are around 1,100 million m3. The dam, therefore, appears to work more like a run-of-the-river project under its present condition. Maximum outflows from irrigation outlets should be 7 million m3 per day under average conditions. These flows need to be corrected based on previous recommendation.

82. The inflows to Dahla reservoir are mainly from snowmelt in Hindukush mountains. These inflows are typically high and for short duration spread over typically three to four months. The reservoir’s additional buffer capacity will maximize storage during these high inflow months and above average years.

83. A hydrology review from 1972 to 1980 estimated peak very wet year annual inflows up to 2,800 million m3 and dry weather inflows of about 550 million m3. The average wet year inflow for the reservoir was estimated as 1,380 million m3. A hydrology review from 1952 to 1980 estimated peak annual inflows up to 2,800 million m3 and dry weather inflows of about 550 million m3. Average wet year inflow for the reservoir was estimated as 1,380 million m3, which is 44 m3/s. The outflows from spillways are not measured at present. Although annual average inflows are estimated at 44 m3/s, high inflow season is typically from February to May i.e. four months only out of 12 months. A reservoir with added buffer capacity is thus critical to store flows for later controlled release and hydropower production. Out of 10 years, one year has been estimated to be a dry year with significantly less inflows.

4. Reservoir Volume and Sedimentation

84. The TRTA team completed a bathymetric survey and a topographic survey in 2018 and collected data which were used in this study combined with data from previous studies.18,19 Bathymetric survey estimated volumes were further improved after topographic survey. The estimated corrected reservoir volumes for the proposed dam raise were:

Present reservoir volume, as of 2018, at FSL (spillway level): 288 million m3; Estimated reservoir volume with 9.1 m dam raise: 588 million m3; and Estimated reservoir volume with 13.6 m dam raise: 782 million m3.

18 Gibson, S. and Pridal, D. 2015. Negotiating Hydrologic Uncertainty in Long Term Reservoir Sediment Models:

Simulating Arghandab Reservoir Deposition with HEC-RAS. SEDHyd: 10th Interagency Federal Sedimentation Conference.

19 Mort, O.D., Ambayec, R.R., and Haase, R.J. 1973. Hydrographic and Sedimentation Survey of Arghandab Reservoir.

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85. Dahla reservoir updated storage curve is presented in Figure 4.

Figure 4. Updated Storage Capacity Curve for Dahla Reservoir

Source: TRTA Consultants, 2018

5. Climate Change Impacts on Reservoir Performance

86. In addition to the sedimentation and the storage loss that it causes, the main challenge for Dahla reservoir and the downstream water users (mainly the irrigation schemes, which are given the lowest priority after other water users) is resulting from strong fluctuations in water availability as a result of climate change. The impacts of climate change on reservoir performance are likely to result in reduced inflow and partly increased maximum flows during extreme events.20 This results in respective differences in downstream water availability. Especially with regards to extreme runoff events, it needs to be understood that the capacity of the reservoir and respectively the buffering capacity is limited (storage capacity is about 11% of the annual inflow under average conditions).

87. Overall, the general climate trend of reduced inflows is of less impact than the increase in extreme conditions and respective water availability fluctuations where the low inflow during dry years or the high inflow during wet years is difficult to be buffered. These differences between wet and dry years are causing the largest challenges for the downstream irrigation schemes as with a reservoir and dam built for average conditions significant spill occurs and over-year buffering is not possible.21

20 TRTA Consultants. 2018. Hydrology Study Report. 21 TRTA Consultants. 2018. Hydrology Study Report.

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6. Drought Frequency Analysis

88. The Helmand River basin experienced an unusually long 5-year drought from 2000 through to early 2005. This was the worst drought since 1830.22 Different types of droughts exist in this basin: meteorological drought (lack of rainfall), hydrological drought (low water fluxes in the hydrologic system), agricultural drought (relates water availability to crop water requirements) or socio-economic drought (includes water supply and demand). No general definition exists, since the occurrence of a drought depends on the actual conditions and water uses occurring in the system of interest. A very broad and general description of a hydrological drought is a situation with “below normal water availability”, where the threshold definition of “below normal water availability” is of key importance and depends on the on-ground situation (the water availability and the demand for the environment and/or anthropogenic needs).23

D. Downstream Water Demands

1. Estimated Downstream Water Demands

89. In the analysis conducted for the TRTA hydrology study, downstream urban water demands were defined as approximately 3 million m3 per month, expected to rise to approximately 7 million m3 per month by mid-century. In addition, an environmental flow requirement of approximately 3 million m3 per month, defined by the TRTA team, needs to be considered, this being a very simple set value used before an agreed and situation-specific developed environmental flow requirement. Irrigation water demands vary during the year but have been approximated by the TRTA team between 32 m3/s and 349 m3/s considering 60,000 ha irrigated area and a typical crop mix with 35% efficiency. Hydropower demands have not been considered as it is assumed that water releases will be channeled through the turbines.24

90. The buffering effect of the reservoir is a significant factor in optimizing water availability and respectively balancing flows between upstream inflow and downstream demands, enabling the operators to distribute flows over time to better respond to downstream demands. For analysis and establishing operation scenarios, the reservoir storage capacity for different elevation levels has been assessed through a bathymetric and topographic survey and evaluation of the reservoir model for depth storage in relation to the potential buffering volume.

2. Reservoir Performance Required

91. Under average conditions, at present dam elevation, in 2018, about 700 million m3 of water is being spilled beyond downstream demands annually - under current climatic and demand conditions and with an irrigation demand tuned to 460 million m3 per annum. In dry years no spill occurs; while in wet years spill significantly increases and irrigation water availability increases.25

92. The analysis shows that raising the dam will lead to increasing irrigation water availability throughout all assessed elevation steps (8 m, 10 m, 13.6 m). A detailed overview of increasing percentage of irrigation water availability as compared to the current dam elevation is shown in Figure 5. The decision for the actual raise will therefore be made based on economic considerations. The A/B/C scenarios for 2050 depict different environmental flow requirements.26 A represents the driest scenario, B the average scenario, and C the wettest.

22 USGS. 2006. Scientific Investigation Report 2006-5182. 23 TRTA Consultants. 2018. Hydrology Study Report. 24 TRTA Consultants. 2018. Hydrology Study Report. 25 TRTA Consultants. 2018. Hydrology Study Report. 26 A more detailed discussion is presented in TRTA Hydrology Study Report, Section Reservoir Analysis Results, sub-

section C.

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Figure 5. Percentage Increase of Annual Irrigation Water Availability for Different Scenarios

Note: The "Driest Future 2050" is the only scenario not leading to an increase, due to the general lack of water inflow. The behavior under Scenario B and C are similar, though increases are less pronounced. Source: TRTA Consultants, 2018

E. Proposed Dam Raise

93. The TRTA hydrology study shows that an increase in reservoir full supply level due to raising Dahla Dam should nearly linearly increase irrigation water availability and reduce spill. Under driest future conditions, no irrigation water should be available for rest of the year for summer crops. However, benefits should be clearly visible under average and wet conditions. Under wet conditions of one year in 10, modelling shows spillway outflows will occur. However, under average conditions the spill at a 13.6 m raise should be zero. The practical limit of dam raise considering long term average flows may then be considered as 13.6 m. Further elevating the dam will not improve irrigation water reliability in average years, as reservoir inflow is the limiting factor.

94. The dam raise will address key development constraints of water and power in the region, prolong dam’s life, ensure increased and more reliable irrigated agriculture and tailored interventions, supply piped water supply to city of Kandahar, and as a by-product provide hydropower generation of 130,000 MWhr/year or 35 to 40% of Kandahar power requirement.

95. Advantages of 13.6 m raise as compared to 9.1 m (equivalent to USACE’s 8.0 m) are (i) the marginal cost is low with some additional resettlement, (ii) it prolongs dam life by allowing increased sediment deposition before capacity falls too far, and (iii) allows increased water to be retained in the dam e.g., for late summer irrigation in wet years.

96. Further technical assessment of the dam raise options is discussed in subsequent sections.

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V. PROPOSED DAM SAFETY UPGRADES

A. Proposed Design Raise

97. The feasibility design considers 13.6 m raise for spillways with 5.0 m free board. The dam raise involves a combination of a parapet wall along the dam crest with limited buttress along the downstream for the main dam. The key advantage of this concept will be the reduced dam downstream footprint with likely cost and time-saving in construction. A consistent 8 m crest width is proposed for all dam raises. For saddle dams, however, due to no downstream footprint concern, parapet wall has not been used. A similar design was used in 66 m Split Rock, 46 m Buffalo and 27 m Quipolly dams in Australia.27,28,29

98. A brief assessment of the safety of the proposed raised embankments by performing slope stability, and other required analyses were made during concept design stage. Feasibility design has added additional defensive design measures and thus are more conservative than concept design.

99. To mitigate risk of seepage from the left abutment of the main dam, grouting is also recommended. To mitigate risks of foundation seepage from the saddle dams grouting along the upstream in selected areas is proposed.

B. Dam Safety Risks and Proposed Remedial Measures

100. Main dam raise concerns for 9.1 m versus 13.6 m raise on downstream outlets and penstock: The topographic survey applied significant corrections and it was concluded that a 13.6 m dam raise footprint was well clear of the new outlets and penstock. The drawings were prepared accordingly. In addition to this, TRTA has used standard design that includes a combination of crest parapet retaining wall. This design has been successfully implemented in Australia for number of dams of similar and perhaps more height.

101. Main dam left abutment shear zone: There is a risk that the main dam left abutment being located close to a 1.22 m to 6.10 m wide curving shear zone behind the promontory open cavern, due to which the dam embankment was moved 30 m upstream during 1952. This zone, unless sealed, may permit seepage in a direction parallel to the river. A grouting program or a wide clay core is foreseen to mitigate this risk. This zone has been stated as highly weathered granite. There is no reported seepage from this zone so far. It was concluded that a filter be introduced along the main dam downstream to mitigate risk of any seepage reaching that zone. However, it is proposed that further investigation using test pits up to 10 m depth or refusal be performed along this zone during detailed design. Should weathered rock continues to this depth, geophysical survey and/or drilling of three boreholes up to 20 m or sound rock depth be performed. This zone is also separately presented in the feasibility drawings. Although additional investigations are proposed, this zone could be grouted after removing highly weathered zone and does not appear to pose risk after treatment to the raised embankment. This zone may alternatively be filled with compacted clay core / engineered fill to sound rock.

102. Spillway design: Two spillways were provided in the original 1952 design. For the raised options, USACE initially considered two spillways on the same locations but later proposed a single RCC stepped spillway. The present study again proposed two spillways at the same locations. Keeping in view the operation and maintenance issues, gated spillway was not considered for all Dahla Dam raised options during feasibility drawings preparation. For economy, CFRD type spillway both with regular straight chute and steeped chute was initially considered but later dropped due to safety considerations. It was concluded that conventional concrete spillways should be consistent for

27 URS. 2003. Lake Buffalo Interim Upgrade Design, Victoria, Australia. 28 URS. 2011. Split Rock Dam, NSW, Australia. 29 GHD. 2011. Quipolly Dam, NSW, Australia.

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the dam raise. This option, however, should be further studied during detailed design to economize the construction of spillways.

103. Another option considered was to use a combination of gated and ungated spillways. This option should further be explored during detailed design and hydraulic model studies are therefore, recommended. Spillway 2 could be considered as partially gated spillway to add further redundancy in design for emergency lowering of water in the reservoir. This option should remove the need for a Fuse plug embankment. However, due to simplicity of operations of spillways, it was considered during feasibility to provide ogee type spillways. It is anticipated that an option for a Fuse plug embankment (say saddle dam 1 extension or at a suitable location with downstream flows to natural or dug stream) with crest elevation of 1153.0 (which higher than the PMF elevation of 1152.3 m) would be further studied during hydraulic modelling of the spillways.

104. To mitigate risks of foundation seepage from the existing Spillway 1 and 2 grouting along the upstream in selected areas is proposed.

105. Dam safety risks mitigation for the case of emergency eminent dam failure: TRTA considered various options to mitigate risks of dam safety for the unlikely case of an eminent dam failure. The installed Howell Bunger valves were reviewed by TRTA and it was concluded that these valves should be safe against 13.6 m dam raise. However, these should be further consulted as per manufacturer’s guidelines as there were significant errors up to 10 m in the survey elevations. The revised discharge plots based on new topographic survey should also be plotted to correct irrigation discharge from outlets.

106. The reported estimated flows from the outlets plus penstocks are 20 million m3 per day at FSL. These flows vary with reference to water elevation in the reservoir. Average inflows to the dam are 40 m3/sec. For an 8 m (USACE) / 9.1 m TRTA raise means 588 million m3 total storage and TRTA is proposing addition of 200 million m3 more in to the storage with 12 m (USACE)/13.6 m TRTA raise. These outlets should need 29 days to evacuate the reservoir for 9.1 m FSL and 39 days for 13.6 m raise FSL under no inflow case. Average inflows to the dam are 40 m3/sec. This should be modelled in the model studies with a gated spillway at Spillway 2 location.

107. TRTA considered an option for adding an additional low-level outlet facility, however, this was concluded that levels along saddle dams and spillway could require long expensive tunneling. An additional low-level facility should be further studied during detailed design.

108. Foundation conditions: Main, saddle dams and two spillways are located in geologically favorable areas with strong to very strong granite and granodiorite foundation rocks. Saddle dams 1, 2 and 1 extension sit on good quality sandstone rock. No shear zone or fault was witnessed during study, geotechnical investigations and field observations. Limited grouting, however, will be required in some areas to check seepage due to embedded sand gravels and permeable zones. This has been presented in feasibility design drawings.

109. Reservoir slope stability issues: Geological drawings for the reservoir were prepared and field observations were also recorded in the drawings. Due to stiff rock and soil structure, there should not be such slope stability risk along the reservoir for raised reservoir. However, there are reaches between main and Saddle Dam 6, where the reservoir will be sitting against existing rocks. It is proposed that an access track be constructed from main dam elevation 1152 m to saddle dams’ elevations 1154 m. This track along cut may be made at 0.25 V:1 H. Should there be any future seepage along the path, then shotcreting and/or other measures may be considered at engineers’ recommendation. The dam FSL is 1149 m and all resettlements and highways up to 1154 m will be relocated to flood safe zones. Therefore, there is negligible risk to any property and infrastructure.

110. Intake tower and trash rack: The outlet works electrical and mechanical components (intake gate fixed wheels and hoist, ring-follower gate and Howell Bunger valves and associated electrical and mechanical components) should be inspected and re-assessment for the proposed dam raise. Further review and investigation is needed to confirm the safety of the replaced outlet works

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(penstocks, valves, etc.) with 13.6 m raise. No as built drawings were available for these structures for TRTA review despite repeated requests to ASBA. These drawings were stated to be in Helmand Office but access to office was not possible. However, available information from 1952 design report has been presented in this report. The raising will also require raising of these structures. It was reported that concrete core testing of these structures was performed during installation of new outlet structures in 2016. TRTA team asked for these results but they are still not available for review. It is desirable that these structures be jointly inspected by a team of geotechnical, electro-mechanical and structural experts and additional investigations be performed if required, before preparing the raised design. It is also proposed that cost of such repairs may be covered through Component 4: Hydropower.

111. Outlet tunnel: As the dam is proposed to be used for hydropower, it is critical that the upstream intake gate be closed during low water in the reservoir, and the tunnel supplying water downstream be thoroughly inspected by a team of geotechnical, rock mechanics and structural experts for any leakage which may endanger the safety of the dam for long-term hydropower operation. A previous 1962 United States Bureau of Reclamation (USBR) tunnel inspection reported 15 liter/sec seepage from the unlined tunnel portion.30 The 5.4 m diameter tunnel is 254 m long and 184 m length is unlined and only 70 m length is concrete lined. It is proposed that the remaining length of the tunnel should also be concrete lined. Once inspection will be completed, additional repairs if any should be completed. It is proposed that cost of such repairs be covered through hydropower component of the project once known.

112. The Route Bearer Highway: Existing alignment was assessed for only raising of the road by using additional fill. A centerline survey and cross section survey at 25 m within 50 m right of way (ROW) was thus performed. However, it was noted that existing road embankment at reaches was already raised up to 10 m with fill. Such an embankment may have significant slope stability risks due to likely escape of fines from the embankment with reservoir filling and drawdown operations. It was noted that the Route Bearer Highway may also need further widening in coming years which were also not possible for a raised embankment. Therefore, it was decided to go for a revised route alignment. The feasibility / tender design is based on the survey available from reservoir topographic survey +/- 0.5 m. This survey is considered consistent for a feasibility level tender design with +/- 30% cost. The tender design was submitted to MEW/MMRD/ADB for approval.

113. Once alignment is approved and contract awarded for construction, a joint detailed survey involving MEW/MRRD, Project Supervision Consultants and Contractor should be performed. This survey has to be performed at 25 m interval along the centerline of road up to full 50 m right of way (ROW) or more where necessary. This survey will then form the basis for actual works and payment. Accordingly, actual project cost will then be updated.

114. Saddle Dam 6: The section may require grouting along the abutments where required.

115. Saddle Dams 1-5 and extensions: All loose foundation fill material will be removed up to a depth of 5 m or sound rock in the case of Saddle Dams 1-5 and their extension. Saddle dams 1 to 5 are known for seepage along foundation. The seepage has been mainly assessed due to presence of sandy gravels along the foundation. A grouting plan has been prepared in the feasibility drawings. The grouting depth will vary. There are also concerns that some embankments might have been designed as a fuse plug as per initial 1952 design report. Therefore, a more conservative approach is proposed.

30 CIDA. 2012. Item 3.7.4, Outlets works refurbishments, page 90, Development Options.

VI. EMBANKMENT DESIGN

A. General

116. Embankment design has been updated from concept design and presented in the following feasibility study drawings;

FS-30- 1 - 3: MAIN DAM FS-31- 1 - 2: SADDLE DAM 6 FS-32- 1 - 4: SADDLE DAM 1 -5.

117. A parapet wall has been proposed for the main dam only with a proposed crest width of 8 m. The design for saddle dams does not use parapet wall as there was no downstream limits for these dams. No new material has been proposed for the construction.

B. Borrow Areas Test Pits Investigations

118. Additional geotechnical investigations were performed along various existing structures to make informed decision on the dam feasibility design. The geotechnical investigation validated that along the existing Route Bearer Highway significant quantity of earth fill should be available for the dam construction. However, processing of this material should be required. As the reservoir area will increase from 29.54 to 45.81 km2 significant material from the existing and proposed raised reservoir should easily be available.

119. A total 23 test pits were made. Details of test pits are presented in drawing No. FS-60-004. Most of the test pits were reported as stiff to hard clay/silt (to claystone/siltstone) and dense sand /gravels (to sandstone). Contractor excavated the Test pits with difficulty as the material was mostly very stiff or dense with very limited moisture. Table 4 presents an overall aggregate summary of the material types and possible locations based on reported test pits data. It was noted that depth of various material varies in test pits. Like sometimes from one test pit various types of material should be available. The number of test pit is accordingly listed in multiple columns.

Table 4. Borrow Area Investigation with Anticipated Material Availability Summary Sr. No.

Material Description Potential Borrow Area as per test pits

Remarks

1 Selected Compacted Sand & Gravel Fill

2, 3, 5, 6, 9, 10, 11, 13, 18,

0 to 2 m gravels are reported in test pits 11 & 12. In test pit 11 below 4 m conglomerates are reported.

2 Random Rolled Fill 1, 2, 4, 5, 6, 7, 15, 16, 18, 21, 22

Sand +silt +clay

3 Impervious Rolled Fill (Clay Core) 1, 2, 6, 7, 8, 12, 14, 16, 17,19, 20 and 23.

Stiff to hard clay / claystone

4 Dumped Rockfill From Spillway and some may be available from excavation along Route Bearer Highway

After Shahjuy Village Route Bearer passes through hilly area. This rock may be use for dam construction as well.

5 Rip Rap - From Quarry Source: TRTA Consultants, 2019

120. Gradation envelope for Clay Core Material in Main and Saddle Dam is presented as Figure 6.

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Figure 6. Gradation Envelope of Clay Core Material


121. Gradation envelope for Clay Core Material and Random Rolled Fill (Sandy Gravel) is presented as Figure 7. Clay core is in filter relation with the Random Rolled Fill. It is critical that this filter relation must be maintained for these two materials for all embankments to mitigate risk of piping. This criteria must met during processing and placement of the material to mitigate risk for piping of the dam. The core thickness and Random Rolled Fill filter downstream has been designed considering this aspect.

122. Rockfill from spillway 1 area will also be available after removal. Gravels and cement should easily be available from Kandahar. Only existing and licensed borrow areas will be used. NEPA will approve the use of quarries.

123. Construction will be implemented during the autumn and winter months when the water level of the reservoir is expected to be low. The existing foundations of the dam will be used to raise the dam. Limited blasting at the existing dam structures will be implemented only above the water level. Like for spillway 2 drilling and blasting should be required. Vibration is expected and the aquatic fauna will search for substitute habitats. No fish losses are expected.

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Figure 7. Gradation Envelope of Clay Core and Random Rolled Fill (Sandy Gravel) Material


124. Grouting or Bentonite cut-off wall construction works for the reaches of the saddle dams will be implemented during the dry season. No impact on aquatic life is expected. The water body of the reservoir will be far from the construction site.

C. Dam Safety Inspection

125. Dahla Dam along with the spillway and the six saddle dikes were inspected by the TRTA international and national dam engineers with the Director of ASBA in January and November 2018. Despite poor maintenance, the project has performed well over the last 66 years. In general, the main dam was noted to be in good condition except the downstream erosion was noted along the sandy gravels. The abutments and groins are in good condition and dry. The spillways were in reasonable condition with some scouring of the stone masonry apron on the downstream of the short height weir. Some erosion of the bed rock appears to have occurred under the high energy flow. A more detailed discussion on individual structures, foundation and abutment conditions and upstream and downstream conditions are included in a TRTA Failure Mode Analysis Report (2018).31

31 TRTA Consultants. 2018. Failure Mode Analysis Report.

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D. Design

1. Main Dam

126. The design assumes up to 5 m excavation of the existing core to eliminate any tension cracks and mitigate risk of high seepage zones. Then the core and other zones will be extended to 1,152 m (WGS84) elevation at existing slope. A 2 m high retaining wall provides additional free board in case of PMF. Although it has been found that core and sandy gravels are in filter relationship, the core shall also be protected with a geotextile bidim A64 or similar to mitigating risk of escape of fines from the dam body in to sandy gravel zones. A 2 m thick sandy gravel zone filter shall be placed along the existing embankment slope to provide additional filter capacity to check seepage. A crest width of 8 m is proposed for the dam. Downstream slope, however, remains the same as on 1952 design, i.e. 1V: 2.5H.

2. Saddle Dam 6

127. The design assumes up to 5 m excavation of the existing core under gravel crest to eliminate any tension cracks and mitigate risk of high seepage zones. Then the core and other zones are extended to 1,154 m (WGS84) elevation at an upstream slope of 1:2.25. Although it has been found that core and sandy gravels are in filter relationship the core shall also be protected with geotextile bidim A64 or similar to mitigate risk of escape of fines from the dam body in to sandy gravel zones. A 2 m thick sandy gravel zone filter shall be placed along the existing embankment slope to provide additional filter capacity to check seepage. A crest width of 8 m is proposed for the dam. Downstream slope, however, remains the same as on 1952 design, i.e. 1V: 2.5H.

3. Saddle Dam 1-5

128. The design for Saddle Dams 1-5 has been performed considering both an upstream core in additional to the original 1952 design and the remaining parts, such as saddle Dam 6. For a 13.6 m raise, a 6 m wide core along the upstream at a slope of 1:2.25 has been proposed. The design assumes 5 m excavation of the existing core to eliminate any tension cracks and mitigate risk of high seepage zones. Then the core and other zones are extended to 1,154 m (WGS84) elevation at existing slopes. Although it has been found that core and sandy gravels are in filter relationship, the core shall also be protected with geotextile bidim A64 or similar to mitigate risk of escape of fines from the dam body in to sandy gravel zones. A 2 m thick sandy gravel zone filter shall be placed along the existing embankment slope to provide additional filter capacity to check seepage. A crest width of 8 m is proposed for the dam. The downstream slope, however, remains the same as on 1952 design, i.e. 1V: 2.5H.

4. Spillway

129. The 1952 design has estimated PMF discharge of 3,760 m3/s for the two spillways. The highest recorded reported flood in the catchment was in 1939 which was about 1,200 m3/s. The highest recorded reported flood in the catchment was in 1985 which was about 3,200 m3/s. A preliminary estimate by USACE states 7,963 m3/s of PMF Inflows for the dam.32

130. For 13.6 m raise the spillways hydraulics design is presented as Appendix 5. Structural analysis is presented as Appendix 6.

32 USACE Dahla Dam Water Improvement Project, Design Documentation Report, Appendix B Hydraulics. Feb 2012

Table 2-1

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E. Assessments and Studies

1. Dam Crest Settlement Assessment

131. Typically, clay core rockfill dams undergo settlements. An analysis of the Dahla Dam height should consider this settlement. These settlements are estimated as percent of height of the dam – a typical estimate is 1% of height for rockfill dams. However, based on recent investigations and considering low plasticity over-consolidated clays in the core and presence of clay and long-term consolidation, Dahla dam may be considered to settle 0.3 to 0.5 % H or even less than this. Considering the 60 m height existing Dahla dam should have settled from 0.18 to 0.3 m in the past, settlement for additional 13 m raise should be in the order of 0.039 to 0.065 m. No additional settlements are anticipated for the existing dam.

132. Figure 8 gives the measured settlements for various dams of the world. This settlement gives the measure of consolidation of the dam core and rockfill. Typically, this results in consolidation of the core and increase in strength due to thixotropic effects in clays.

133. It was noted during additional geotechnical and topographic survey that dam materials, both at the dam and potential borrow area, were high to very high strength sandy gravels. Dam core was noted to be over consolidated and very stiff clays. These clays in existing dam core have very high strength and should undergo limited to no consolidated settlements. Borrow area clays and silts were also reported to comprise over-consolidated clays and should offer significant thixotropic strength gain over time after construction. It is proposed that these clays/silts from borrow areas be tested further after 7 days, 28 days and four months compaction at optimum moisture content for triaxial and shear box testing.

134. It was however, noted that dam crest widths of the saddle dams were increased from 6 m to over 8 m at various locations. It was also noted that dam crest levels were almost 1 m less than the main dam. It appears that these saddle dams were deliberately placed 1 m below the main dam. This means that a free board of 4 m has successfully worked for these dams and they have also worked as potential fuse plug embankments. No history was available that when and why this was done. Seepage from the saddle foundations has been reported when the dam was up to and above FSL.

135. Due to absence of the settlement markers along the crest of the dams, this important measure of dam safety has been missing for Dahla Dam. It is proposed that during detailed design settlement markers and piezometers be designed at various locations.

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Figure 8. Crest Settlements of Central Core Dams (Dumped Rockfill)

Source: URS Corporation. 2003. Buffalo Dam Design Report

2. Deformation Under Additional Loads

136. The forward prediction of embankment deformation behavior needs to be estimated based on the historic performance and factors to be taken into consideration are to include:33

(i) Deformation due to the increased load of a raised embankment; (ii) Differential deformation between the upstream shoulder, core and downstream

shoulder; (iii) Ongoing potential for accelerations in deformation on large drawdown; and (iv) Earthquake induced deformation (and differential deformation) shall be assessed

for earthquake induced embankment deformation.34

137. Embankment raise options involving a structural element, such as a parapet wall, shall consider the effect of differential deformation on the long-term performance of the structure. Camber allowance shall be provided for a design life of 100 years.

3. Design Water Levels

138. The estimated design water levels for analysis were based on pool elevation profile curves for various probabilistic loadings for 13.6 m raises. These elevations are as follows:

2-year pool elevation = 1,149.47 m 5-year pool elevation = 1,149.68 m

33 Hunter. G. and Fell. R. 2003. The Deformation Behavior of Embankment Dams. University of New South Wales,

Sydney. 34 Pells. S. and Fell. R. 2002. Damaging and Cracking of Embankment Dams by Earthquakes and the Implications for

Internal Erosion and Piping. UNICIV Report No. R-408. School of Environment and Civil Engineering, the University of New South Wales.

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200-year pool elevation = 1,150.57 m PMF = 1,152.30 m Dam rest elevation = 1,154.00 m

4. Site Specific Seismic Hazard Study

139. In 2007, the U.S. Geological Survey completed an extensive study to date of potential seismic sources in Afghanistan and developed probabilistic ground motion maps to help quantify the expected frequency and strength of ground shaking in the country.35

140. An Operational Basis Earthquake (OBE) event normally corresponds to a 144-year return period. However, to date there is no published probabilistic Peak Ground Acceleration (PGA) developed for a 144-year event in Afghanistan. Therefore, the 475-year event was selected as the OBE event (which is conservative). The OBE was assigned a return period of 500 years while the Maximum Design Earthquake (MDE) was assigned a return period of 10,000 years for embankment. Table 5 summarizes the OBE and MDE RPs and the PGA. PGA recurrence plot should be prepared in future studies.

Table 5. Return Period and PGA for Embankment OBE and MDE Return period (years) PGA (g)

Embankment OBE 500 0.075

Embankment MDE 10,000 0.18 Source: USGS. 2011. Dahla Seismic Write-up.

141. In 1952, the dam structures were designed to resist inertia forces produced by a ground wave-acceleration equivalent to 0.05 gravity. As this ground acceleration is too low in today’s practice for high dams with high hazard consequences, USACE initiated geotechnical investigations in 2014 for determining the shear strength parameters. The deterministic seismic hazard analysis performed by USACE in 2014 yielded a peak ground acceleration of 0.32 gravity at the foundation rock level for a magnitude 6 earthquake. The damage class for Dahla Dam is thus class 1 on a scale of 0 to 4 and the corresponding probability of transverse cracking at the crest is 0.05 which is very low. The maximum crack width in the event of a magnitude 6 earthquake could be 50 mm.

142. In December 2017, the TRTA engineers inspected the dam crest; no longitudinal cracks were observed on the dam crest and the parapet wall alignment indicates that the crest has settled by less than 1% of the embankment height over the last 60 years of dam operation. This is in line with the assessment reported above. A further assessment of dam settlement has been discussed in subsequent sections.

143. In 2018, the TRTA performed further geotechnical investigations on the main dam crest, saddle dam 6 (which was not surveyed by USACE), saddle dam 1 and borrow areas. The proposed dam raise has been performed to ensure that core and filter zones are wide enough and in filter relation to mitigate risk of piping. The results show that Saddle Dam 6 has also been constructed using similar clay core material as that of main dam. Investigations revealed no dam safety risk for further raising of the dam. The proposed dam raises use downstream raised method for all main and Saddle dams, this method is conservative. Additional redundancy in design has been added by increasing core thickness. The dam raise will use similar existing construction material with filter relations to mitigate piping risks.

144. The gradation curves for main and saddle core are presented in Figure 6. The gradation curves for main and saddle core with sand-gravel zones are presented in Figure 7. A review of

35 USGS. 2011. Dahla Seismic Write-up.

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Figure 7 indicates that the two materials are in filter relation and if the dam will be constructed on similar material there should not be a piping concern.

145. From the TRTA studies, it was concluded that, despite the absence of a properly designed no-erosion filter, the main and saddle dam 6 embankments of Dahla Dam are safe against internal erosion or piping failure. A total of 27 stability cases were run for the dam models. These included the 1952 design, 8 m raise, and 13.6 m raise for the main dam and saddle dam 1-6. The analysis concluded that under proposed design, all of the dams are safe for the water full supply level, dam crest floods and seismic loads.

146. During the detailed design it is important that geotechnical investigations performed be reviewed further and if required additional investigations may be performed. The material characterization from previous reports from Helmand should also be studied and gradation envelopes be further developed for tender works. The thickness of filter zones should be developed further and if required more processed filters may be used.

5. Seepage and Slope Stability

147. Static slope stability analyses of the dam slopes were performed under various loading conditions considering the existing and proposed raised main dam with the parapet wall under concept design stage. The feasibility design has added additional defensive design measures increasing safety in design. The analyses results indicated that, in general, the calculated factors of safety are either above or close to the minimum requirements as set out in the design criteria.

6. Material Properties

148. The density and shear strength parameters for the embankment materials were selected from the literature and limited laboratory and field tests results available from previous studies. Additional geotechnical investigations also validated selected strength parameters selected during concept design stage. It is anticipated that during detailed design various analysis will be re-validated.

149. It was noted that most embankment fills contain significant amount of clays and silts. Table 6 presents the Atterberg Limits Test Summary from the USACE report.36 Therefore, a homogenous type of material is usually easily available in nearby borrow areas.

Table 6. Atterberg Limits Summary Dahla Dam

Sample Moisture

content (%) min-max (avg)

Liquid limit (%) min-max

(avg)

Plastic limit (%) min-max

(avg)

Plasticity index (%) min-

max (avg) Embankment fill (n = 152) 1-28 (8) 21-37 (25) 15-27 (30) 0-13 (4) Disintegrated rock (n = 15) 2-12 (8) 22-26 (23) 16-25 (22) 1-5 (3) Borrow area 1 (n = 9) n/a 27-42 (33) 16-25 (21) 2-24 (12) Borrow area 2 (n = 21) 4-9 (6) 20-34 (26) 16-26 (20) 2-13 (6) Borrow area 3 (n = 1) n/a 22 18 4 Borrow area 4 (n = 10) n/a 16-33 (27) 14-32 (26) 1-4 (2) Route Bear Highway realignment (n = 66)

3-16 (9) 20-47 (29) 13-43 (22) 2-17 (7)

Note: n = number of tests conducted. Source: USACE. 2014. Geotechnical Report (Louis Berger Report).

150. Based on Table 6, an assessment for the core material strength characterization based on the National Engineering Handbook was performed. A plot of Atterberg Limits Vs Friction Angle is

36 USACE. 2014. Geotechnical Report – Louis Berger Report.

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presented as Figure 9, this reveals that for a maximum reported liquid limit of 47, the embankment clay core should have an estimated angle of internal friction of 18 degrees.

Figure 9. Friction Angle vs. Liquid Limit Plot

Source: USDA. 1997. National Engineering Handbook. Chapter 52.

151. A total of nine (9) Consolidated Undrained Tests were requested during tender stage for additional investigations. Two tests were requested on Main Dam and One (1) was requested on Saddle dam 6. Six (6) tests were requested on the borrow areas samples. The investigations are summarized below;

152. Main Dam: For main dam two boreholes and one test pit were performed. The boreholes were performed up to 4 m deep whereas test pit was made 3 m deep. SPT refusal was noted for BH#1 with approximately similar results for BH#2. The material reported appeared highly compacted and consolidated over time. Test pi reported silty gravels with sand -GM.

153. The core typically starts at 2 m below the dam crest and reported to have about 40 % silts and clays with 40 % sand and 20 % gravels in first borehole. As per USCS the core is stated to be SC to SM-SC or ML. The core has only 3 to 4% low moisture with a specific gravity of 2.7. Liquid limit, Plastic Limit and Plasticity Index are reported as 22, 16 and 6 %. However, in borehole 2 it is reported as Non-Plastic from 3 to 4 m depth. Consolidated Undrained Triaxial (CU) test report an effective cohesion (c’) of 22 kPa and effective angle of internal friction (ø’) as 33 degrees. The reported permeability is 5 x 10 -10 m/sec. The material above 2 m is non-plastic and comprises 10 to 15% clays and 34 to 43 % sands and remaining as gravels. The reported permeability is 1.5 x 10 -9 m/sec. Insitu density was reported as 1.989 g/cc and wet as 2.018gm/cc. Test pit remolded samples report Maximum Dry Density (MDD) as 2.05 /cc and an Optimum Moisture Content (OMC) as 9.6% for the material above core. Two additional Consolidated

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Undrained Triaxial (CU) test report an effective cohesion (c’) of 18 and 12 kPa and effective angle of internal friction (ø’) as 36 and 39 degrees. 154. Saddle Dam 6: For Saddle dam 6, 5 boreholes and one test pit were performed on the dam crest. Another test pit was performed along downstream of the dam. Boreholes 1 to 3 were drilled up 25 m depth. BH#2 was drilled in the middle of the dam. SPT refusal along the full investigated length was reported. Borehole 4 and 5 were drilled to 3.7 and 4 m depth. Test pit 1 was made to 2.6 m depth. Similarly, for BH4 and 5 refusal was reported.

155. As per USCS the core is stated to be CL, SC, CL-ML to SM-SC. The core typically starts at 2 m below the dam crest, is inclined as per 1952 design and reported to have about 40 to 60 % silts and clays with 30 to 40% sand and remaining gravels in borehole number 2. The core has 3 to 9% moisture with a specific gravity of 2.7. Liquid limit, Plastic Limit and Plasticity Index are reported from 17 to 40, 12 to 15 and 5 to 26 %. Consolidated Undrained Triaxial (CU) test report an effective cohesion (c’) from 14 to 30 kPa and effective angle of internal friction (ø’) from 25 to 28 degrees. Insitu density has been reported as 2.1 gm/cc. Test pit remolded samples report Maximum Dry Density (MDD) as 1.86 g/cc and an Optimum Moisture Content (OMC) as 15%. This appears to require further reduction in moisture content to 10% or so. For the Main Dam MDD was reported higher like 2.05 gm/cc at 10% moisture. Therefore, it appears that under 10% moisture content, MDD should be higher. The material above 2 m is non-plastic and comprises 10 to 15% clays and 34 to 43 % sands and remaining as gravels. The reported permeability is 2 x 10 -9 m/sec for the material above core.

156. The clays were highly over-consolidated and have Insitu strength. These clays should be available in significant quantity at the reported sites. These clays typically have high thixotropic strength gain after compaction like the existing clay core for the existing dam. The reported Maximum Dry Density (MDD) ranges from 1.7 to 1.85 gm/cc at moisture range typically around 20%. This appears to require further reduction in moisture content to 10% or so. For the Main Dam MDD was reported higher like 2.05 gm/cc at 10% moisture. Therefore, it appears that under 10% moisture content, MDD should be higher. This should be further validated during detailed design. Typically, same consolidated triaxial strength parameters could be used for these soils as stated above for Main and Saddle dams. However, it is proposed that Contractor must perform additional geotechnical investigations on proposed borrow areas including CU Triaxial tests before construction and validate remolded strength and thixotropic strength. Thixotropic strength gain may be estimated on samples compacted to 98% SMDD and left for 28 and 90 days testing in a closed moist container.

157. The material parameters used in the stability analyses have been developed from the results of previous and recent TRTA (2018) proposed field and laboratory testing, a review of the construction records and construction methods used to place the materials, and information from case studies using similar materials. The development of geotechnical characterization of the various embankment material types is discussed previously.

158. The density, shear and other strength design parameters for embankment materials were selected from laboratory and field tests results and subsequently verified and updated if necessary, through literature review and presented in Table 6. For the analyses, it was assumed that foundation rocks were intact with no joint openings under stress and hence no potential shear surfaces could pass through the foundation rock.

159. TRTA (2018) geotechnical investigation validated that the strength design parameters selected for the core material during concept design were significantly conservative. Minimum effective cohesion as per triaxial tests was 12 kPa and minimum effective angle of internal friction was noted as 27 degrees. Typically, 1/3 of the average of all the tests may also be considered. This will lead to even higher parameters. Therefore, it can be concluded that with these minimum

55

reported parameters, the dam should have higher factor of safety for the cases analyzed during concept design. It should be noted that for the tested cases, the estimated factors of safety were already above the minimum permitted for dams. TRTA propose that for impervious rolled fill (clay core) c’ be taken as 12 kPa and phi‘ as 27 degrees. Other parameters are also updated in the table below.

Table 7. Proposed Material Parameters for Seepage, Stability and Stress Analyses

Material/zone

Permeability (m/sec)

Unit weight

Modulus of

Elasticity (E)

Poisson’s Ratio (µ)

Drained strength

Concept Design

Drained strength

recommended Final design

Undrained strength

parameters

Kh Kv kN/m3 MPa c'

(kPa)

’ (deg)

c'

(kPa)

’ (deg)

cu

(kPa)

u

(deg)

Selected compacted sand and gravels

10-3 10-4 20 100 0.35 5 35 5 38 - -

Random roll fill (filter)

10-3 10-4 20 50 0.3 5 34 5 38 - -

Impervious rolled fill (clay core)

10-8 10-9 19 50 0.3 5 18 12 27 100 0

Dumped rockfill 10-2 10-2 20 4000 0.1 0 45 0 45 - -

Reinforced concrete (cracked)

10-3 10-3 24 7000 0.15 100 45 100 45 - -

Source: TRTA Consultants. 2018, based on: (i) Bowels, (1997), Foundation Analysis and Design, 5th edition; and (ii) Look, G. Burt, (2007), Handbook of Geotechnical Investigations and Design Tables

160. It is anticipated that additional triaxial and direct shear testing will be performed during detailed design on various borrow area fills to validate the above testing.

7. Piezometric Levels

161. The piezometric levels used in the models for long-term static stability analyses are typically taken directly from piezometric data. However, no such record exists. Recent USACE investigations and subsequent TRTA additional geotechnical investigations have validated that the moisture content of the core is significantly less than saturation moisture content.37 The analysis performed during concept design assumed limited cases of FSL and PMF conditions. Subsequently, seepage analysis should be performed, and phreatic surfaces could be developed based on that analysis. For cases of reservoir drawdown, the phreatic surface should be assumed to be maintained at steady state level within the upstream fine filter and core of the embankment.

8. Loading Cases Analyzed During Concept Design Stage

162. The following load cases should be selected and analyzed:

(i) After 13.6 m raise: Design for main dam, Saddle Dam 6 and Saddle Dams 1 to 5 with extensions: FSL steady state conditions; PMF flood conditions; and MDE.

163. The additional cases need to be analyzed during detailed design should include:

(i) Rapid drawdown from top of flood with new data; (ii) Flood during construction;

37 USACE. 2016. Spillway Drawing Set.

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(iii) Flood at top of new parapet wall; (iv) Flood at top of new parapet wall 1,152.3 m and 1,154 m with tension crack.

9. Embankment Stability Design Criteria

164. Table 8. presents the proposed embankment stability design criteria as per USBR Design Standards no. 13-4: Embankment Dams. It includes loading conditions for during construction, end of construction, long-term (steady state), draw down, flood and earthquake.

Table 8. Design Criteria for Embankment Stability Load case Factor of safety

Long-term steady state seepage 1.5

Short-term drawdown 1.3

Maximum flood level 1.3

Post-earthquake – MDE 1.1

Construction – reservoir full 1.5

Source: USBR Design Standards No. 13-4: Embankment Dams.

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VII. PROPOSED INVESTMENT PROJECT OUTLINE

A. Outputs and Activities

165. This project component will contribute to the overall integrated water management investment outcome: Improved management and use of water resources in the Arghandab River basin. The overall outcome will be contribution to improved water resource management and rural economic growth. This outcome is based on the full integrated water resources investment project of raising the dam, irrigated agriculture, urban and peri-urban water supply, and hydropower.

1. Key Outputs

166. This outcome will be supported by 17 outputs:

Table 9. Key Project Outputs Output Number Description 1 Raise of main dam plus Intake tower, tunnel lining and trash rack; 2 Raising of Saddle Dam 6; 3 Raising of Saddle Dams 4 and 5; 4 Raising of Saddle Dams 3 to 1; 5 Extension of Saddle Dam 1; 6 Spillway 1; 7 Spillway 2; 8 Geotechnical instrumentation; 9 Site security fence; 10 Electrification along dam; 11 Resettlement; 12 Road realignment; 13 Operation and maintenance; 14 Dam safety staff training; 15 Staff colony and security camp; 16 Park; and 17 International Panel of Expert (POE).


2. Key Activities

167. Output 1: Raise of main dam plus intake tower, tunnel lining and trash rack. This activity will include the following infrastructure types of work:

Raising of main dam from 1140.9 to 1154 m with an increase in length of the dam from 535 m to 755 m.

Additional geotechnical investigations were performed along various existing structures to make informed decision on the dam feasibility design. The geotechnical investigation validated that along the Route Bearer Highway significant quantity of earth fill should be available for the dam construction. However, processing of this material should be required. As the reservoir area will increase from 29.54 to 45.81 km2 significant material from the existing and proposed raised reservoir should easily be available.

Typically, low reservoir volume periods are from July to November. Most construction could be planned in such days with minimal risk of spillway flows. Contractor has to design his own coffer dams to protect under construction spillways and structures.

Collection of existing structures drawings of intake, trash rack and tunnel from Helmand.

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Detailed inspection of these project structures from a group of experts in electro-mechanical, structural (shotcrete), geotechnical and rock mechanics.

A planned tunnel Inspection to decide whether concrete lining / shotcrete / pre-cast lining may be used to line the unlined reaches of the tunnel.

Preparation of the updated design and cost estimate. Raising of the existing 5.2 m diameter intake tower from elevation 1136.4 to 1158

m elevation with an existing 0.4 m wall thickness. Raising of the existing 2.6 m x 12.37 m wide two trash racks from 1136.5 m to 1150.5

m elevation. Concrete lining of the remaining 184 m length of the inlet / outlet diversion tunnel.

168. Output 2: Raising of Saddle Dam 6. This activity will include the following infrastructure types of work:

Raising of Saddle Dam 6 from 1140.9 to 1154 m with an increase in length of the dam 6 from 180 to 510 m;

Widening of the dam crest width from 6.4 to 8 m and Saddle Dam 6 extension increase in crest width with Spillway 1 from 8 to 12 m.

169. Output 3: Raising of Saddle Dams 4 and 5. This activity will include the following infrastructure types of work:

Raising of Saddle Dams 4 and 5 from 1140.9 to 1154 m with an increase in length of saddle dams 1-5 from 1,515 to 1,995 m;

Widening of the dam crest width from 6.4 to 8 m; Saddle Dam 5 extension increase in crest width with Spillway 1 from 8 to 12 m and Saddle Dam 4 extension increase in crest width with Spillway 2 from 8 to 12 m.

170. Output 4: Raising of Saddle Dams 1 to 3. This activity will include the following infrastructure types of work:

Raising of Saddle Dams 1 to 3 from 1140.9 to 1154 m with an increase in length of saddle dams 1-5 from 1,515 to 1,995 m;

Saddle dam 3 extension increase in crest width with Spillway 2 from 8 to 12 m;

171. Output 5: Extension of saddle dam 1; Saddle Dam 1 extension from station 5+150 to 5+600 with dam crest elevation at 1153.0 m to act as fuse plug embankment. The crest will be protected with concrete 0.15 m thick from elevation 1147 and downstream will be rock armored.

172. Output 6: Spillway 1. This activity will include the following infrastructure types of work:

A detailed model study of the proposed structures to calibrate the design of for either ogee and broad crest weir spillway structures;

Consider options for a gated spillway at Spillway 2 location to add redundancy in design for emergency drawdown if required;

If gated spillway will be use, then fuse plug embankment could be eliminated; Calibrate the design of the proposed fuse plug embankment if still considered after

Spillway 2 will be converted to partially gated facility; Constructing a coffer dam for construction of the spillway; Constructing a new concrete Spillway adjacent to old Spillway 1 from 1135 to 1149

m with a 220 m long overflow weir abutting against rock.

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173. Output 7: Spillway 2. This activity will include the following infrastructure types of work:


Look at options for a gated spillway at Spillway 2 location to add redundancy in design for emergency drawdown if required;

If gated spillway will be use, fuse plug embankment could be eliminated; Calibrate the design of the proposed fuse plug embankment if still considered after

Spillway 2 will be converted to partially gated facility; Constructing a new concrete Spillway adjacent to old Spillway 2 from 1135 to 1149

m with a 120 m long overflow weir abutting against embankments.

174. Output 8: Geotechnical instrumentation. This activity will include the following infrastructure types of work: Plan, prepare design drawings, procure and install geotechnical instrumentation which may include settlement markers, piezometers, and seismographs.

175. Output 9: Site security fence. This activity will include the following infrastructure types of work: Installation of a security fence along the boundary of the dam.

176. Output 10: Electrification along dam. This activity will include the following infrastructure types of work:

Electrification of the dam access road and instruments rooms; Connection with the proposed hydropower small units or diesel generators.

177. Output 11: Resettlement. This activity will include the following infrastructure types of work: Extensive coordination between ADB, MEW, ASBA, ARAZI and other government departments along with the affected people. This activity is covered separately in another report.

178. Output 12: Road realignment.38 This activity will include the following infrastructure types of work:

Realignment of the road to allow for future use as an express way; Construction of the new raised Route Bearer Highway (Kandahar – Bamian

Highway);

179. Output 13: Operation and maintenance. This activity will include the following works:

A study, design and installation of a Seasonal Forecasting Tool for Kandahar basin. This has to be done by a hydrologist / Meteorologist. He can prepare the TOR for this work and give an estimate of the staff and training requirements. This will require close coordination with MEW, ASBA, EPA, Weather Bauru and Kandahar government. This will involve procurement of the equipment, installation in Kandahar in an approved building and hiring and training national staff in Afghanistan;

Management of the operation and maintenance of the dam; Capacity development of ASBA by hiring relevant engineering and operational staff.

Numbers and positions need to be discussed and agreed with ASBA and MEW; Engineers (civil, hydrologists, hydraulics, geotechnical, electrical, mechanical, GIS)

and Staff for operation of the dam safety emergency response vehicles. Preparation of the operation and maintenance manuals for the dam in close

coordination with MEW / ASBA and other relevant agencies for;

38 More information are provided in Part B of the report.

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a. The dam operational safety; b. The dam safety emergency response;

Training to the dam safety staff for emergency response; a. ASBA staff; b. Other relevant emergency response organizations;

Procurement of emergency response equipment and vehicles for ASBA / MEW (Table 10). This requires a schedule and a close coordination with MEW and ASBA for purchasing;

Provision of the inhouse mechanical and electrical workshop for the maintenance of these vehicles;

Provision for the POL (petrol, oil & lubricants) and maintenance of these vehicle for the project duration say 2020 to 2025;

Table 10. Proposed Procurement of emergency response equipment and vehicles Serial

Number Type of Equipment /Vehicle Quantity Potential Users

1 Land Cruiser Prado Vehicles 2 ASBA management 2 Toyota Hilux double cabin SRS 4 x 4 or

equivalent 4 ASBA Senior staff working

on dam safety 3 Toyota Hilux single cabin 4 x 4 or equivalent

vehicles 4 ASBA Junior staff working

on dam safety 4 Long reach boom excavators Komatsu or

equivalent 2

ASBA technical support staff working on dam safety

5 Wheel loaders WA470-7 Komatsu or equivalent 2 6 Dump trucks HM-400-5 Komatsu or equivalent 2

7 Smooth wheel double drum 12 tons rollers

Komatsu or equivalent 2

8 Dozers D39EXi/Pxi-23 Komatsu or equivalent 2 9 sheep foot roller 12 tons Komatsu or equivalent 1 10 9HP Walk behind Double drum roller 1


180. Costs for these dam safety activities are expected to be spread over five years and need careful management. It is assumed that subsequently Afghan government /MEW will be able to manage the O&M costs.

181. Output 14: Dam safety staff training. This activity will include the following activities:

Dam Safety training to engineers and staff for the emergency response, evacuation. Training contents and training has to be prepared and managed by the project consultants during detailed design / construction stage in close coordination with MEW and ASBA;

Providing on the job dam safety training to MEW, ASBA and relevant staff to manage day to day operation of the dam.

182. Output 15: Staff colony and security camp. This activity will include the following infrastructure types of work:

Planning, design and construction a staff colony at dam site in close consultation with MEW, ASBA and other dam operators and government agencies;

Planning, design and construction a security camp at dam site in close consultation with MEW, ASBA and other dam operators and government agencies.

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183. Output 16 will involve construction of a park downstream of the dam site to provide re-creational facility to locals. The soil for it should be available from construction along Route Bearer Highway along existing agriculture land. A concept design has been prepared and this design will be further designed during detailed design stage.

184. Output 17 will involve selection of an appropriate international panel of expert to review tender, construction and subsequent operational phase of the dam. POE will be supported by relevant national experts to support POE.

185. Output 1 to 15 excluding 12 will have one activity:

Advise Afghanistan on the recommended approach for proceeding with the project and prepare the required contractual documentation. The options to be considered are:

a. Allow Component 1 to be developed with a combination with Component 4 via PPP. This has been extensively studied under a separate funding from the ADB;

b. Engage an international detailed engineering design firm with support from local firms to act as owner’s engineer and then subcontracting various project components to local contractors to proceed with the construction. The design of the project structures has been considerably simplified to support hiring local contractors. This will create significant employment opportunities in the region.

c. An EPC contract with an international firm to act as EPC. d. Engage a Design, Build and Operate Contractor.

186. Output 12 can be considered as a standalone activity: Engage a local contractor with support from MEW, Ministry of Public Works, ASBA and ARAZI for the construction of the realigned road. As the road realignment will be required other departments involving resettlements will also have to be coordinated.

187. Output 1 will have following additional activities before commencement of the construction:

Collection of existing drawings of intake tower, trash rack and tunnel and other outlet structures drawings from Helmand;

Detailed inspection of the project structures from a group of experts in electro-mechanical, structural (shotcrete), geotechnical and rock mechanics;

A planned tunnel inspection to decide whether concrete lining / shotcrete / pre-cast lining may be used to line the unlined reaches of the tunnel;

Update of analysis and design; Preparation of the updated design and cost estimate.

188. Output 6 and 7 will have following additional activities before commencement of the construction:


Consider options for a gated spillway at Spillway 2 location to add additional discharge capacity and redundancy in design for emergency drawdown if required.

If option (ii) will be preferred, then fuse plug embankment may be eliminated; Calibrate the design of the proposed fuse plug embankment if still considered after

Spillway 2 will be converted to partially gated facility.

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3. Construction Planning

189. Proposed project schedule is provided as Appendix 2.

190. All main construction works should be planned in such a way that these works should have limited or no effect on the irrigation supplies except raising the intake tower, trash rack and tunnel lining (optional). This aspect has been carefully considered and the proposed construction of these structures is only during dry months from July to December when there will be limited or no supply for irrigation (as per MSWA report, ASBA has some irrigation flows requirements for July, August and September and no supplies requirements from November to February under present conditions). Moreover, the dam has only one outlet from where irrigations supplies are provided to the downstream area. The water enters in to supply tunnel through trash rack, which clears debris only from entering in to system, reaches intake tower structure. A certain gate opening is permitted through electro-mechanical / crane system to allow required flows to downstream outlets through the tunnel. The supply tunnel from intake to downstream is lined and unlined at certain reaches. About 184 m is unlined that should need lining. The tunnel is the only diversion structure which was constructed during 1952.

191. Proposed construction does not require any other diversion structure. Therefore, the construction should be planned in close coordination with ASBA in dry months with limited or no supplies from the dam. Ideally, in dry months with limited water in the reservoir (July to December) and more specifically no irrigation water demand for irrigation.

192. The design of intake tower, trash rack and tunnel lining will be prepared after obtaining 1952 design drawings from Helmand Province and inspection is conducted by the team comprising structural, geotechnical, rock mechanics, hydraulics and electro-mechanical experts.

193. As ASBA have local experience of managing flows from the intake structures using existing gates, a close coordination will be required and has to be agreed by the visiting team. A proposed construction schedule has to be agreed at the detailed design stage.

194. Should the raising of the intake and trash rack and tunnel lining is planned rather than going for the construction of new structures, irrigation supplies could be affected during the structural raise and when electro-mechanical equipment will be removed and replaced. The structural works for raising should preferably be planned using rapid hardening high-strength concrete so that installation of the electromechanical equipment could be started as soon as practical after the desired design concrete strength is achieved and validated.

195. Tunnel lining will require closure of supplies for irrigation works. Tunnel lining should preferably be pre-cast structures so that a length of 184 m could be completed as soon as possible along with raising of the intake and trash rack structures.

196. The electro-mechanical items for intake tower, trash rack and tunnel lining could be considered as long lead item for the procurement purposes to avoid any unnecessary delays so that effect on irrigation supplies could be minimized.

197. The raise / construction of these works should not preferably be taken along with construction of both spillways to avoid any unexpected flood although probability is extremely low. However, one spillway (e.g. spillway 2) could be constructed to allow for any unexpected flows through spillway 1 or vice versa.

198. Care shall be taken to advise farmers many months in advance of any plans to stop releases if any different ASBA's existing zero release periods, so that they can plan their cropping programs.

199. Construction site-camp is already existing near the saddle dam-6 and is an open area, with paved ground surface. This site is close to both saddle-dam-6, and main dam. The same place is

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used by 1952, as well as by 77-turkish company construction crew. There is more than enough space for construction machinery, and other site camp activities and dumping wastes. The dumping waste site is adjacent to the dam site along downstream of the dam. The site is far from local residences.

200. Typically, low reservoir volume periods are from July to November. Most construction could be planned in such days with minimal risk of spillway flows. Contractor has to design his own coffer dams to protect under construction spillways and structures. Similarly, various material for construction should be procured early so that most construction could be completed during low reservoir levels. The contractor may propose robust measures to economize and speedy construction for approval of the engineer.

201. The project will be subdivided in to number of sub-components to encourage use of local contractors. The typical machineries involved the project will include cranes, long reach boom excavators, loaders, dumpers, graders, dozers, smooth wheel drum rollers, sheet foot rollers, walk drum rollers, water tanks, and sprinklers, etc. The contractor will also establish various batching and processing plants like concrete and asphalt. The contractor will also establish various processing plants for dam body material like, clay core, filters, sands and gravels, rockfill etc.

202. The dam design has been simplified to allow use of local contractors. There are number of local civil construction contractors who should be able to manage most part of the civil works like dam and spillway construction. This was confirmed by ASBA and MEW.

203. Works like raising of intake tower and trash rack may require skilled international contractor with significant experience in managing electro-mechanical components of these structures. One preferable option would be to allow these structures to be constructed under Component 4 as hydropower contractors typically have construction experience of such structures.

204. The tunnel lining, if required, could be considered as pre-cast panel structure to expedite construction. This must also be planned well in advance as well to allow for placement during dry months. This may require tunnel to be inspected a season before construction.

205. A planning for long lead items will be required. Long lead items have to be identified at the earliest and procurement of these items must be started soon to avoid delay in the construction to avoid unnecessary claims.

206. Recent geotechnical investigations have confirmed availability of significant quantities of the construction material along clay core, sand gravel mix, rockfill from the extended reservoir area. Rockfill should also be available from spillway area excavation. Drilling and blasting need careful planning. As this area is clear of the reservoir, contractor can easily start processing and stockpiling of the material for use during low reservoir time. This is a critical activity and must be managed carefully well in advance to ensure availability of enough material for construction. The contractor must perform his own investigations to validate the availability of the construction material from various sources and develop strength parameters before start of construction. Like cement and gravels can be obtained from various local quarries and are easily available in Kandahar. The proposed wall along main dam crest should be pre-casted well in advance to place on dam crest during dry months. All filters and other materials must be stockpiled before the start of the dry season to complete the construction with in dry months.

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B. Cost Estimates

207. Estimated base costs for project activities are about $231.0 million excluding taxes and duties. Details are provided as Appendix 1. A break down is presented in Table below;

Table 11. Estimated Project Cost Output Indicative base cost estimate

($’ 000) Output 1: Raising of main dam 71,043

Output 2: Raising of Saddle Dam 6 13,562

Output 3: Raising of Saddle Dams 4 and 5 9,458

Output 4: Raise of Saddle Dams 3 to 1 8,038

Output 5: Extension of Saddle Dam 1 3,221



Output 8: Instrumentation 2,000

Output 9: Site security fence 1,000

Output 10: Electrification along dam 1,000

Output 11: Resettlement 10,529

Output 12: Road realignment 16,360

Output 13: Operation and maintenance 5,000

Output 14: Dam safety staff training 2,000

Output 15: Staff colony and security camp 3,000

Output 16: Park 2,000

Output 17: International Panel of Expert (POE) 511

Subtotal 190,314

Security (10% of Subtotal) 19,031

Contingencies (11% of Subtotal) 20,934

Total base cost 230,280

Taxes and duties -

Total 230,280 Source: TRTA Consultants, 2019

208. Assumptions in Cost Estimation; Following assumptions were considered for the cost estimation:

All roads on dam crest will be gravel base. Excavation should be re-used after processing. Borrow areas are along the reservoir

area which will inundate due to raise. All blasted / excavated rockfill say from spillway foundations or others should be re-

used as rockfill in dams; Hill side road treatment between Main and Saddle Dam 6 is optional and should be

revisited detail during detailed design. The spillway has been considered to be constructed for Reinforced Concrete. Other

options to reduce should be considered. Tunnel lining for a length of 184 m has been considered. This should be revisited

after actual inspection and may be removed if required. Intake, Trash rack and tunnel lining has been estimated as lump sum cost due to

absence of the data yet to be reviewed from Helmand ASBA office, and should be worked out in detailed cost estimate.

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C. Human Resources and Equipment

1. Human Resources

209. Approximate number and categories of job opportunities likely to be created directly and indirectly as a result of proposed construction are presented in Table below;

Table 12. Approximate number and categories of job opportunities Type/Profession Implementation

(number males) Operation & Maintenance

(number males) Resident Site Engineers Civil, Geotechnical, Mechanical, Electrical, Hydraulics with B.Sc Engineering Degree and 10-15 years’ experience (one each)

5 2

Assistants Resident Site Engineer Geotechnical, with B.Sc Engineering Degree and 5 years experience

3 1

Assistants Resident Site Engineer Hydraulics, with B.Sc Engineering Degree and 5 years experience

3 1

Assistants Resident Site Engineer Mechanical, with B.Sc Engineering Degree and 5 years experience

2 1

Assistants Resident Site Engineer Electrical, with B.Sc Engineering Degree and 5 years experience

2 1

Assistant Engineer Civil, with B.Sc Engineering Degree and 3 years experience or Diploma holder with 8 years experience

5 2

Assistant Engineer Geotechnical, with B.Sc Engineering Degree and 3 years experience or Diploma holder with 8 years experience

3 2

Assistant Engineer Mechanical, with B.Sc Engineering Degree and 3 years experience or Diploma holder with 8 years experience

5 2

Assistant Engineer Electrical, with B.Sc Engineering Degree and 3 years experience or Diploma holder with 8 years experience

5 2

Assistant Engineer hydraulics, with B.Sc Engineering Degree and 3 years experience or Diploma holder with 8 years experience

1 2

Assistant Engineer Civil / Civil 3D/ AutoCAD, with B.Sc Engineering Degree and 3 years experience or Diploma holder with 8 years experience

3 1

Work Supervisor, Diploma holder with 3 years’ experience 20 0 Administrator 5 2 Administration Staff 10 2 Clerical Staff 20 4 Skilled Labour 200 5 Unskilled Labour/helpers 500 0

Total 791 32 Source: TRTA Consultants, 2019

2. Equipment and Machinery

210. Following is the typical list of equipment, which should be required during the implementation stage of the subproject. The contractor will provide the equipment and machinery required for execution of this subproject.

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Table 13. Equipment and machinery required for Implementation Equipment / Plant Quantity

Long Boom Excavators 5 Front end loaders 10 Dump trucks 30 Grader 5 Steel smooth wheel drum roller 5 Vibratory roller 5 Water Tanks 20 Crane 70 ton 2 Mobile crane 50 ton 2 Concrete mixer 10 Asphalt Plant 1 Crusher plant 1 Processing plant 1 Drilling / Grouting plant 3


D. Procurement

211. The proposed project implementation and management arrangements are detailed in Project Procurement Plan. This is likely to include;

Consulting Services Packages: and Goods, Works, and Non-consulting Services Packages.

1. Consulting Services Packages

212. Proposed consulting services for the detailed design of the project will cover both C1 and C2 contract.

213. The proposed packages will cover the consulting services and capacity building of various departments involved in the projects. Proposed packages are presented in Table below.

Table 14. Consulting Services Packages

Package Number

General Description

Estimated Value ($)

Selection Method

Review Type of

Proposal Advertisem

ent Date Comments

C1-CS-1

Project Management Supervision (C1+C2), Detailed design for C1 (including geotechnical investigations, seismological studies), Detailed design for C2 (irrigation works), Survey & Design of ASBA Priority works, & Dam Safety Staff Training

14,000,000 OCB Prior FTP Q2 2019 QCBS 90:10, international advertising and shortlisting

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C1-CS-2

Consultancy for Capacity building of new AIS Operating Entity (includes – C2: Technical system training for water mgmt. & irrigation system mgmt., calibration of water level gauges, Institutional Water resources allocation, management & use)

8,000,000 OCB Prior FTP Q2 2019 QCBS 90:10, international advertising and shortlisting


2. Goods, Works, and Non-consulting Services Packages

214. Proposed project implementation and management arrangements are estimated in small packages to encourage small bidders and local procurement. The proposed packages are presented in Table below.

Table 15. Goods, Works, and Non-consulting Services Packages

Package Number

General Description

Estimated Value ($)

ProcurementMethod

Review Bidding

Procedure

Advertisement

Date Comments

C1-LW-1 Lot 1: Raising of Main Dam – Section 1 (includes intake tower, tunnel lining and trach-rack)

84,500,000 (Value to be split between Lots based on

decision on the sections/

slices)

OCB Prior 1S1E Q2 2020 Design-build works contract, international advertising

Lot 2: Raising of Main Dam – Section 2

C1-LW-2 Lot 1: Raising of saddle dams 4 & 5

11,300,000 OCB Prior 1S1E Q2 2020 Design-build works contract, international advertising

Lot 2: Raising of saddle dam 6

16,000,000

Lot 3: Raise of saddle dams 3 to 1 & Extension of saddle dam 1

13,400,000

C1-LW-3 Lot 1: Spillway 1 construction


Lot 2: Spillway 2 construction

19,500,000

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C1-LW-4 Road realignment


C1-LW-5 Lot 1: Site security fence

1,200,000 OCB Prior 1S1E Q2 2019 Works contract, national advertising

Lot 2: Staff colony & security camp

3,600,000

C1-LW-6 Electrification along dam

1,200,000 OCB Prior 1S1E Q3 2020 Works contract, national advertising

C1-G-1 Instrumentation

2,300,000 OCB Prior 1S1E Q3 2020 Goods contract, international advertising

C1-NCS-1

Operation & Maintenance

6,000,000 OCB Prior 1S1E Q3 2020 Non-consulting services contract, international advertising


E. Implementation

215. As part of the project approval phase, recommended approach for proceeding with the project and preparation for the required contractual documentation is provided in Procurement Plan.

216. The government will establish a Project Management Unit (PMU) with a Project Director and associated staff and facilities. Implementation consultants will work from this office under supervision of the Project Director. The proposed implementation arrangement will have to be confirmed through discussion by ADB and the government. The following are suggestions based on the TRTA institutional capacity assessment.

217. MEW at federal level and ASBA typically manage Dahla Dam. However, implementation will also involve several other stakeholders like ARAZI, Public Works Department, SEPS, the Afghan electrical utility, DABS and several local and provincial departments covering irrigation and municipal water supply component.

218. Considering future hydropower use, multiple agencies are likely to involve in the management of the dam and hydropower operation. This should include a close coordination between MEW, ASBA, Da Afghanistan Breshna Shekat (DABS) and SEPS among others.

219. The design reflects and encompasses the priorities of the MEW as expressed in the Afghanistan National Development Strategy (2007). The design is aligned with the Water Law (2009),39 which formalized the adoption of integrated water resources management principles within national water sector policies and sector strategies of MEW, MAIL, MRRD, Ministry of Urban Development and Housing, Ministry of Mines, Ministry of Public Health, and the NEPA which all

39 Water Law. Official Gazette. Ministry of Justice. Islamic Republic of Afghanistan. Issue # 980. 26 April 2009.

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have direct mandates in the water sector. The design reflects the priorities of ASBA who at present manage the irrigation flows from the dam.

F. Governance

220. All civil works and other activities will be implemented according to government law and ADB procedures for financial management and safeguards. Throughout the project design, government representatives have been closely consulted and contributed valuable governance measures that have been incorporated project design.

221. Extensive public communication will be carried out regularly with stakeholders, and any grievance will be dealt with efficiently under the established grievance redress mechanism.

G. Safeguards

1. Social

222. A resettlement survey is in progress. Social analysis is being done for the whole of the project. All civil works will be subject to resettlement safeguards, in particular compensation for any loss of private land to public use.

223. The approach and interventions of the project are socially inclusive, gender-focused, and community-led. The project will cover poor and vulnerable households, including those headed by women. The framework for inclusion of the poor and vulnerable will ensure targeted coverage of poor and vulnerable households through the financial instruments developed under Output 3 and 4, while offering new employment to both rural and peri-urban women, youth and the disengaged under-employed sector of communities.

224. The consultation and participation plan for the project will maximize participation of stakeholders. A gender equality and social inclusion action plan will ensure that gender and social activities will be implemented and monitored at regular intervals. Data, disaggregated by sex and social and economic background, will be collected annually as part of monitoring and evaluation, to establish trends from the baseline social survey undertaken during TRTA. This will enable figures to be tracked and social and gender equality results to be measured and reported, as the project progresses. In recognition of the wider social and structural dimensions of gender inequality in the country, the project is expected to yield significant benefits for women, as summarized in the gender equality and social inclusion action plan.

2. Environmental

225. Initial environmental impact assessment has been made for the whole project. Environmental impact assessment and environmental management plans will need to be carried out for each civil works activity, although many (e.g. dam raising, road realignment etc.) may be grouped for this purpose. The project will be category A, with significant potential environmental impact.

226. The project is categorized as low risk for climate change impact and in practice will reduce emissions through use of generation of electrical power using hydropower replacing diesel generation and also removing the need for continual and ongoing extraction of ground water from boreholes by improved water storage of natural annual rainfall and snow melt water. Another positive impact will be the reduction of water loss from spillways with consequent ability to enable environmentally minimal flows to be maintained in the main river networks of the river delta and its linked canals. Climate risks were considered based on the sample subprojects.

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H. Risks and Mitigation Measures

227. There are a number of potential risks to the completion of works and successful achievement of the proposed outputs (Table 16). These risks include security concerns at the dam site, availability of contractors, dam site flood risks, availability of construction material, timely and fair compensation to the affected people. There were number of construction activities completed successfully at the dam site in recent years like re-construction of irrigation outlets and penstock facility, refurbishment of the intake tower and raising of part of the Route Bearer Highway. The support from the locals is very high and with appropriate government measures the project could be managed successfully.

Table 16. Summary of Risks and Mitigating Measures Risks Mitigating measures

Availability of local contractors

The dam design has been simplified to allow use of local contractors. There are number of local civil construction contractors who should be able to manage most part of the civil works like dam and spillway construction. This was confirmed by ASBA and MEW.

Delay in Re-settlement along proposed reservoir

This is a critical activity and will require careful due diligence and management before raised reservoir filling. MOF, MEW, ASBA and ARAZI with support from ADB should be able to manage it. Part of the area is still occupied by non-governmental forces. However, there is strong desire in the public to get additional water through dam raise. Re-Settlement surveys are in progress and an estimated cost has been prepared and added in the dam cost.

Construction of intake tower, Trash rack and tunnel lining

Works like raising of intake tower and trash rack may require skilled international contractor with significant experience in managing electro-mechanical components of these structures. One preferable option would be to allow these structures to be constructed under Component 4 as hydropower contractors typically have construction experience of such structures. The tunnel lining, if required, could be considered as pre-cast panel structure to expedite construction. This must also be planned well in advance as well to allow for placement during dry months. This may require tunnel to be inspected a season before construction.

Flooding of the dam site Typically, low reservoir volume periods are from July to November. Most construction could be planned in these months with minimal risk of spillway flows. Contractor has to design coffer dams to protect under construction spillways and structures and will be responsible for managing the flood risks. The contractor may propose robust measures to economise and speedy construction for approval of the engineer.

Availability of construction material

Recent geotechnical investigations have confirmed availability of significant quantities of the construction material along clay core, sand gravel mix, rockfill from the extended reservoir area. Rockfill should also be available from spillway area excavation. Drilling and blasting need careful planning. As this area is clear of the reservoir, contractor can easily start processing and stockpiling of the material for use during low reservoir time. This is a critical activity and must be managed carefully well in advance to ensure availability of enough material for construction. The contractor must perform investigations to validate the availability of the construction material from various sources and develop strength parameters before start of construction. Cement and gravels can be obtained from various local quarries and are easily available in Kandahar. The proposed wall along main dam crest should be pre-casted well in advance to place on dam crest during dry months. All filters and other materials must be stockpiled before the start of the dry season to complete the construction with in dry months.

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Close coordination between civil works and hydropower works contractors

This will require a strong team coordinator with the owner’s engineer to ensure that all construction activities are well planned and timely coordinated between various contractors.

Identification and procurement of long lead items

A planning for long lead items will be required. Long lead items have to be identified at the earliest and procurement of these items must be started soon to avoid delay in the construction to avoid unnecessary claims.

Unnecessary govt delays in customs on internationally procured items

MEW should identify long lead items and based on experience should plan the schedule to ensure that no delay is caused due to red tape.

Poor planning for the construction

A detailed project plan should be prepared identifying all the critical activities with close coordination with the relevant government departments.

Weak supervision of works Improve field security and ensure adequate budget is available in timely manner.

Lack of local security for field staff does not allow freedom of movement

Project risk managers and security team work closely with local police and security senior personnel and community leaders, while the project employs and upskills locally born and resident field staff.

Local leaders subvert project direction in favour of own preferred projects

The broad base of Steering Committee Governance membership and the management group of the PMU with independent monitoring and evaluation functions will ensure development plans and input applications are agreed in advance and stay within project parameters.

Availability of skilled and capable local staff limits progress in key agricultural or added value activities

The project will recruit local staff and expect to upskill these in the first six months of employment in a train the trainer approach, including exposure to conditions outside Afghanistan through study tours and placements in the first year of activity with intermittent repeat exposure: International specialists will only be used to support local staff and the project will foster a bottom up introduction through stimulating demand for produce rather than a top down imposition of ideas, once key areas have begun to develop.

Local governance fails to understand and support integrated project methodology

Close relationships will be developed early in the program with local governance bodies, including the Provincial Governor’s office, enjoying positions within the Steering Committee, along with bottom up initiatives being supported by rural and peri-urban communities, political figures, ANA/ANP leadership, etc.

Kandahar region suffers substantial and prolonged drought

Climate resilience and how to live with water deficits will be part of the regional and community upskilling messages given in field and ICT based communications and media.

Currency value depreciation and fluctuations make forward budget planning very difficult

The currency of transactions internally will be Afghanis and external purchases will be made in USD or Euros with hard currency for capital items drawn down from external sources as and when required. Currency depreciation will favour exports which are within scope of the project and which will earn foreign currency to recycle for input purchases under commercial mechanisms.

Component 1 and 2A unable to deliver promised benefits of more and reliable irrigation water

Climate resilient farming techniques and technologies assume irrigation supplies will not always be available and drought resilience will be built in to cropping patterns with early warning communications to assist irrigation management.


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VIII. PANEL OF EXPERT TERMS OF REFERENCE

A. General and Purpose

228. A Panel of Experts (POE) shall be established for the review of the Dahla Dam Raise Project by the Ministry of Energy and Water (MEW), Govt of Afghanistan to undertake periodic, comprehensive and independent reviews with the objective of evaluating features and actions pertaining to the safety and providing recommendations to the MEW of actions that may be needed to upgrade the dam and appurtenances to acceptable safety standards. The POE shall be guided by the Dam Safety Assurance objectives and the related legislative regulations, standards and guidelines.

229. The POE shall be established for reviewing the tender documents including final detailed design and technical specifications before tendering commences and shall be maintained for the duration of the project, until initial reservoir filling and start-up phases until all facilities are placed into final operation. The POE will provide due consideration to the administrative procedure /guidelines of the GOI and the (World Bank) WB safeguard policies including OP4.37 under the guidance of the MEW.

230. The MEW will nominate appropriate national experts to support POE. These national experts will support the POE during its performance of the POE function during tender/detailed design, construction and post construction stages and provide the relevant project information to the Team Leader POE for compilation of the final fact-finding reports.

B. Organization and Membership

231. The POE shall contain core members with expertise in the disciplines required for the project.

232. A dam engineering / geotechnical specialist with significant experience in the design and construction supervision of zoned earth-rockfill dams including ones in high seismic zones. In particular, the review will include borrow area material selection, design and construction quality control manuals, ground / foundation treatment like cutoffs or grouting, slope stability, seepage and settlement analysis, geotechnical and seismic instrumentation and dam break studies. In coordination with a seismologist, the seismic hazard assessment study will be updated if necessary and dynamic stability / stress-strain analyses of the dam under seismic loads will be reviewed. The review will also include geotechnical investigation and treatment works of the foundation of the dam and associated structures, main dam left abutment shear zone treatment, intake tunnel lining, raise for trash rack and intake tower, slope stabilization of the abutments of main and saddle dams and reservoir areas if needed. Upon discretion of the dam specialist, it could request a dedicated geologist or geotechnical engineer with material characterization experience from borrow areas, slope stability, seepage analysis, geotechnical instrumentation, rock mechanics expertise if it encounters any particular issues that would warrant such an expert’s inputs and advise appropriate design improvements.

233. A seismologist with ample experience of seismic hazard analyses and assessment, design criteria for design and construction for large zoned earth-rockfill dams including ones in high seismic zones. The expert will review and assess the dam site geology, seismology, potential fault zones in dam reservoir, likelihood of dam break due to a seismic event, previous seismic hazard assessment works by USGS, adequacy of seismic hazard assessment in both deterministic and probabilistic approaches and potential liquefaction and rupture of the foundation by fault movements. The expert will guide on any additional survey, investigation, and analyses if needed. The expert will review the previous proposed seismic design criteria and update it if necessary.

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Based on his recommendations, the dam and structural design of structures should be updated if required. The seismologist may be released upon review and acceptance by the expert of the seismic hazard assessment and relevant design aspects and advise appropriate design improvements.

234. A hydrologist / sediment specialist with ample experience in hydrologic and sediment assessment for large dams and seasonal flow forecasting system design and review is needed for hydrology and sediment assessment/management study review. The hydrology review includes the hydro-meteorological assessment and flood routing of the inflow design flood and sizing of spillway facilities as well as water supply reliability/security against hydrological variability. The expert will review and advise on models prepared by EWater Australia and findings of MSWA studies. The sedimentation assessment, bathymetric surveys, dam break studies and management plan will be reviewed, and appropriate due diligence will be provided to update any design or design assumptions. The expert will review the hydrology / hydraulics design assumptions for the spillways and flood control structures. The hydrology expert may be released upon review and acceptance by the expert, of the hydrological assessment /safety, and sediment assessment/management plan and advise appropriate design improvements.

235. A structural engineer with experience in structural and seismic analysis and design of intake towers, trash rack, spillways, main dam crest and other retaining walls, dam abutments structures and tunnel lining will review the raised design of these and other structures. The expert will review and advise in detail the 1952 design and subsequent maintenance design of USACE and review the raised design for 13.6 m Full Supply Raise. The expert will accordingly advise if the proposed design was consistent with international best practice and safe for the region and advise appropriate design improvements.

236. A hydraulics engineer with ample experience in hydraulic modelling and design of gated and ungated spillways and energy dissipater, low level outlet, water intakes /outlets, irrigation supply valves, diversion tunnel, fuse plugs etc. The expert will review in detail the 1952 design and subsequent maintenance design of USACE and review and advise on the raised design for 13.6 m Full Supply Raise. The expert will review the hydraulic modelling studies, dam break studies and advise accordingly on adequacy of design of various hydraulics structures.

237. An electro-mechanical expert with ample experience in raise design of dam intake and trash rack structures and irrigation supply valves to review the raised design of intake tower, trash rack, tunnel management, and irrigation supply lines. The expert will review in detail the 1952 design and subsequent maintenance design of USACE and review the raised design for 13.6 m Full Supply Raise and advise appropriate design improvements.

238. International Geotechnical /Rock Mechanics / Grouting Expert experience in geotechnical, and seismic analysis and design of intake, trash rack, spillways, retaining walls, dam abutments structures, tunnel lining and foundation grouting. The expert will review in detail the 1952 design and subsequent maintenance design of USACE and review the raised design for 13.6 m Full Supply Raise.

239. Depending on the nature and size of the job it may be appropriate to include, in addition to these disciplines, and as per the MEW discretion:

An expert on the design and construction of power plants (if any), irrigation supply valves and appurtenant waterways to review the design of the power station;

A planning engineer civil engineer who has a good background in layouts, scheduling and construction techniques, and contract packaging and management that may be critical in a large or complex project oversight.

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240. A Chairman shall be appointed amongst the members by the MEW to coordinate the communications of the POE, to call and chair its meetings, to ensure the memberships objectivity and to provide balance to its reviews and recommendations. The person responsible for the official correspondence with the POE Chairman shall be the MEW Deputy minister. The latter will appoint a liaison official for regular interaction with the POE.

241. The POE and the MEW shall establish a list of experts and specialists in subcategories of the disciplines mentioned above such as dam engineering, geotechnical, seismology, grouting, concreting, sedimentation, materials testing, rock mechanics, electrical, mechanical, hydropower, hydraulics, or construction supervision. The POE may then choose at their discretion qualified experts from such list to perform special assignments or evaluations on short notice and to report results directly to the POE.

242. The POE will meet as frequently as necessary depending on the status of the dam involved but no less than two times a year during the preparation and initial construction phases and once a year throughout construction and start-up. For review of design stage, meetings shall be held at such intervals to assure the POE of the adequacy of design data collection, foundation exploration, design parameters, foundation analysis, dam raised section design and determination and routing of the design floods and dam break studies. During the construction phase, at least one meeting will be scheduled just as the foundation treatment of dams in raised sections is opened to where critical conditions relating to foundation treatment or need for additional excavations, grouting can be observed. One key issue will be investigations and construction work along main dam left abutment shear zones. Meetings may also be convened at the request of the MEW.

243. The POE meetings will normally be at the project site and shall be attended by all members. Inspection of the site, design of the dam under construction individually should occur only under special circumstances and in such cases the member will send his report of findings to other panel members for issuance jointly after concurrence by all panel members.

244. An advance schedule of meetings will be drawn up by the POE and the MEW and sent to the GOI and ADB to allow them to send an observer to POE meetings if they so desire. The Bank will not participate in any manner in the proceedings or discussions.

C. Specific Actions

245. While the POE will review and evaluate mainly technical elements of the dam designs, they shall not be concerned with the project scope, general features or economic characteristics. The specific elements to be reviewed and evaluated by the POE shall include but not be limited to the following:

D. Tender Preparation Phase

To review site exploration data for the foundation and for material sources including results of drilling or boring, laboratory testing, in-situ tests and regional and local geological characteristics;

To review the designs of the foundation treatment, proposed excavation, selected foundation strength parameters and seepage control measures;

To review the strength parameters and characteristics of the selected construction materials for the rockfill dam including zoned materials, such as core, filters, riprap, etc. as well as their laboratory test results and placement /compaction requirements;

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To review the selected aggregate source, cement type, and material characteristic for concrete structures including results of durability, gradation and reactivity tests, trial mix designs, strength design parameters, and construction requirements;

To review the result of the seismic hazard assessment and appropriateness of the seismic safety design criteria and analyses and assess any additional needs for seismic hazard assessment and guide on any additional survey, investigation, and analyses. In particular, the review will include the assessment of any potential faults crossing the dam site and reservoir area as well as mitigation measures if required;

To review stability analysis and resulting factors of safety for normal, unusual and extreme loading conditions for the main dam and associated structures, spillways /energy dissipating structures and outlet works;

To review upstream conditions in regard to formation of reservoir landslide or ice dams (glacier) if any and handling of floods caused by the collapse of such natural dams;

To review the reservoir related factors, such as reservoir rim slope stability, resulting wave action, their effect on dam stability, potential seepage, handling of debris, etc. as well as countermeasures if needed;

To review the flood hydrology methodology and computations for determining the project design flood hydrographs, reservoir routing and spillway sizing as well as safe yield and reservoir simulation;

To review sediment assessment and management plan including effective operation of bottom outlets for sediment flushing / sluicing if possible as well as other mitigation measures;

To review the modelling studies and design of spillway facilities including flow conditions, energy dissipation or need for modeling;

To review the inlet and outlet works, including its hydraulic designs, capacity for emergency reservoir drawdown, sediment handling capability, selective thermal releases, regulation range and other factors;

To review the designs of diversion works, schedule, hydrology and risk factors associated with diversion during construction and with the closure of diversion works at initial reservoir filling;

To review the risk and hazard evaluations including need for dam breach analysis and inundation study as part of the Emergency Preparedness Plan (framework plan);

To review the design for dam instrumentation and the program for collecting, evaluation and maintaining data to be obtained as well as preliminary operation and maintenance plan;

To review the final plans and specifications for design adequacy, construction, scheduling as well as the owner’s quality control procedures and construction supervision plan;

E. Construction Phase

To make at least one field inspection of the nearly completed foundation excavations prior to placement of either embankment or concrete (Mandatory for POE members covering geology, dam engineering and foundation engineering);

To make at least one field inspection during the early phases of placement of the rockfill dam section, to evaluate quality control manuals, procedures being used during construction and to evaluate if materials being utilized and construction methods being employed are meeting design parameters and contract specifications;

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Assess the result of instrumentation installation (including measurement datum marks) basing on early data collected during the construction on that basis recommendations to MEW regarding data collection, revision (supplementation) of instrumentation in line with the construction progress are made;

To review the operation & maintenance plan, dam safety staff training, dam break studies, emergency preparedness plan for initial reservoir filling, covering including the time of closure, maximum allowable filling rate, measurements, emergency release plan, and designation of responsible operating personnel;

Review the progress and monitoring reports prepared by the Supervision Consultants.

F. Long Term Operation Phase

To review and evaluate the organization, procedures and program to carry out long term independent monitoring of the dam safety status including the inspection frequencies, instrumentation records system, project data files, evaluation criteria and means to provide remedial actions; and

To review and assess the adequacy of operation and maintenance plan/manuals, and establishments of project operations procedures;

To review and evaluate emergency plans including downstream flooding effects, emergency reservoir drawdown, notification of anticipated risks to the authorities in the downstream areas, system of early flood warning, major flood early warning systems, major flood spilling operations plans, and site access during emergencies;

To review the procedures for handling project records, including as built drawings, operation records, inspection records, instrumentation data and other information associated with the long-term safety of the dam.

G. Implementation Duration and Contract

246. The following project implementation schedule is currently foreseen:

Tender Preparation Phase: From January 2020 to June 2021 Construction Phase: From July 2020 to December 2021 Operation Phase: From January 2021 to December 2022

247. Phased contracts will be signed. This contract can be signed for the tender preparation phase and construction phase. The contract for operation phase will be performed later. Proceeds of the Component 1 loan to this project shall be used for this purpose.

H. Support Services

248. The MEW designers and engineering consultants, if any, shall be present during selected POE meetings at the request of the POE. The POE will be provided the necessary background information, any relevant data, notes or explanations regarding the designs, computations or methods used. The MEW Chief Engineer for Dahla Dam Project will coordinate the assembling of such information. The POE may ask the designers to conduct additional studies to assist in evaluation of the matters relating to the dam safety status.

249. The MEW will assist to allow prompt travel clearance(s) of POE members or specialists requested by the POE and in providing full physical access to the project sites.

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I. Meetings of the POE

250. The POE shall meet and undertake field inspections as frequently as necessary, during all phases. The panel will propose its periodic working missions depending on requirements in each phase of project implementation subject to be agreed by MEW, but not less than twice a year in each phase. The dam raise works are planned in small tenders to be completed from July 2020 to December 2021 i.e. one and a half (1.5) years. For the initial year of the construction phase, POE is recommended to organize its meetings quarterly say in July, October and January. Then additional meetings may be organized during July and October 2021 i.e. a minimum of 5 POE meetings. Additional meetings to other technical subjects can be held at request by MEW or the panel members.

251. The working missions of the POE will be at MEW head office in Kabul and/or at the dam/ construction site with participation of all permanent members. POE meetings shall be record in minutes, signed by all members and submitted to MEW. Minutes of the meetings shall briefly outline areas of concern, request for additional more profound analysis, present recommendation for action, if any. A copy of each minutes of meeting and supplementary reports will be transmitted by MEW, GOI to the ADB.

J. Reporting

252. The reports of POE shall be prepared, signed by all members and presented to MEW, prior to the departure of the members. Any item urgent to the safety of the dam should be brought immediately to the attention of MEW in writing in a special brief communication, prior to the submission of mission reports.

253. The POE may be required to work with other relevant agencies and entities in the project, design and supervision consultant and contractors to clarify relevant issues. The POE may also prepare other reports if required.

254. The POE shall not perform any remedial designs but should give general recommendations for potential solutions and approaches for corrective or rehabilitative measures.

255. MEW will provide copies of each mission report and minutes to the GOI and Asian Development Bank. MEW may append a statement of actions taken on recommendations of the previous panel meeting.

K. Required Expertise and Inputs

256. The tables below present the required expertise, inputs and proposed number of missions for the international and national panel of experts.

Table 17. International Panel of Expert (IPOE) Input Missions Summary Sr. No.

International Expert Input (weeks)

Missions (number)

1 International Dam / Geotechnical Expert / Team Leader 10 5 2 International Hydrologist Expert 4 2 3 International Seismologist 4 2 4 International Structural Expert 4 2 5 International Hydraulics Expert 4 2 6 International Electro-mechanical Expert 4 2 7 International Geotechnical /Rock Mechanics / Grouting Expert 4 2 8 International Geotechnical / Dam Material Expert 4 2


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Table 18. National Panel of Expert (POE) Input Missions Summary Sr. No.

National Consultant Input (weeks)

Missions (number)

1 National Hydrologist Expert 12 2 2 National Seismologist 12 2 3 National Structural Expert 12 2 4 National Hydraulics Expert 12 2 5 National Electro-mechanical Expert 12 2 6 National Geotechnical /Rock Mechanics / Grouting Expert 12 2 7 National Geotechnical / Dam Material / Borrow Areas Expert 16 5 8 National Dam Operations and Maintenance (O&M) Expert 12 2


257. Table 20 describes the overall schedule of the POE meetings. MEW will provide the ADB with further detailed programs for review in a timely manner.

L. Criteria for Selection of Consultants

258. The POE expert should meet the minimum requirements as below:

Each International Expert besides Master’s degree in required majors should be fluent in English and have a minimum of 20 years of work experience in respective professional areas.

Each national expert besides Master’s degree in required majors should be fluent in English and have a minimum of 10 years of work experience in respective professional areas.

Table 19. Criteria for Selection of Panel of Expert (POE) Expert Expertise Required

Dam Designs and Construction Expert (international)

• Having worked as an expert in designing and construction of large dams with over 25 years’ experience.

• Intensive knowledge and experience in earth and rockfill dam design and construction arrangement, procedure and quality control.

• Intensive experience in preparing construction plan and schedule for large-scale or complex works including rockfill dam.

• Expertise in assessing foundation conditions and recommending practical solutions for treatment works including curtain and consolidation grouting.

• Expertise in assessing geological conditions of abutment and reservoir rim and required safety measures

• Knowledge of seismic design and design of structures in high seismic zones

• Knowledge of analyzing monitoring data collected during the construction and operation phases.

Seismologist (international)

• Having worked as an expert for large dams with over 20 years’ experience. • Expertise in seismic hazard assessment including deterministic and

probabilistic approaches, the assessment of active faults/lineament, reservoir triggered earthquake assessment, etc.

• Experience in the formulation / examination of required seismic motion inputs for dynamic stability / stress-strain analyses of dams in coordination with dam design experts

• Experience in seismic hazard assessment in high seismic zones similar to the project area

Hydrology /Sediment Expert (international)

• Having worked as an expert for large dams with over 20 years’ experience. • Expertise in hydrological assessment of large dams

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• Experience of using latest software and programs in hydrology, flood routing and dam operation.

• Expertise and experience in sediment assessment and management including sediment flushing/sluicing, dredging, excavation, etc. and use of modern computer simulation models

• Knowledge in reviewing design of major hydraulic structures, such as spillway, intakes, bottom outlets, etc.

Structural Expert (international)

• Having worked as an expert for large dams with over 20 years’ experience. • Expertise in structural assessment of infrastructure relating to large dams • Experience in structural and seismic analysis and design of intake, trash

rack, spillways, retaining walls, dam abutments structures and tunnel lining. • Experienced in the raised design of intake tower, trash rack and tunnel

structures with reference to crane design and structural requirements; • Experience in reviewing and preparation of Quality control manual for dam

structures construction; • Experience of using latest software and programs in structural engineering

and applications in dam operation. • The expert will review in detail the 1952 design and subsequent

maintenance design of USACE and review the raised design for various structures for 13.6 m Full Supply Raise.

• Knowledge in reviewing design of major hydraulic structures, such as spillway, intakes, bottom outlets, etc.

Hydraulics engineer (international)

• Having worked as an expert for large dams with over 20 years’ experience. • Expertise in hydraulics assessment of infrastructure relating to large dams • Experienced in hydraulic modelling of spillways; • Experienced in detailed design of gated and ungated spillways, energy

dissipater, low level outlets, water intakes /outlets, irrigation supply valves, diversion tunnel, fuse plugs etc.

• Experienced in Dam Break assessments; • The expert will review in detail the 1952 design and subsequent

maintenance design of USACE and review the raised design for 13.6 m Full Supply Raise.

Electro-mechanical Expert (International)

• Having worked as an expert for large dams with over 20 years’ experience. • Expertise in hydraulics assessment of infrastructure relating to large dams

and hydropower; • Experienced in hydraulic modelling of irrigation and hydropower supply

valves; • Experienced in the raised design of intake tower, trash rack and tunnel

structures with reference to crane design and structural requirements; • Experience in reviewing and preparation of Quality control manual for dam

structures construction; • The expert will review in detail the 1952 design and subsequent

maintenance design of USACE and review the raised design for 13.6 m Full Supply Raise.

Geotechnical /Rock Mechanics / Grouting Expert (International)

• Having worked as an expert for large dams with over 20 years’ experience. • Experience in geotechnical, and seismic analysis and design of intake, trash

rack, spillways, retaining walls, dam abutments structures, design of tunnel lining and foundation grouting;

• Experience in various types of grouting methods and its applications in dam engineering;

• Experience in rock mechanics and review works for the design of lining for the hydropower tunnels;

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• The expert will review in detail the 1952 design and subsequent maintenance design of USACE and review the raised design for 13.6 m Full Supply Raise.

Geotechnical / Dam Material / Borrow Area Expert (international)

• Having worked as an expert for large dams with over 20 years’ experience. • Experience in large dam design and material selection and processing from

borrow areas; • Experience in seepage, slope and settlement assessment for large rock

filled dams; • Experience in reviewing and preparation of Quality control manual for dam

site construction; • Experience in laboratory testing like consolidated undrained triaxial and

shear box testing; • Experienced in material strength characterization for various soils types and

application in dam engineering; • Experience in geotechnical instrumentation design and review;

Hydrologist (national)

• Expertise in large dams’ hydrology design and other major hydraulic infrastructure projects

• Experience in similar projects in other countries

• Familiarity with the national hydrological conditions and issues Seismologist / Geologist / Geotechnical Engineer (national)

• Expertise in large dams’ seismology design and other major hydraulic infrastructure projects

• Experience in similar projects in other countries

• Familiarity with the national seismological conditions and issues Structural Engineer (national)

• Expertise in large dams’ structural design and other major structural infrastructure projects

• Experience in similar projects in other countries • Familiarity with the national structural design conditions and issues

Hydraulics Engineer (national)

• Expertise in large dams’ hydraulics design; • Experienced in Model Studies and other major hydraulic infrastructure

projects • Experience in similar projects in other countries

• Familiarity with the national / regional hydraulics laboratories and issues Electro-mechanical Engineer (national)

• Expertise in large dams’ electro-mechanical infrastructure design and other major infrastructure projects

• Experience in similar projects in other countries • Familiarity with the national electro-mechanical standards design conditions

and issues Geotechnical / Rock Mechanics / Grouting / geologist (national)

• Expertise in large dams’ • Geotechnical investigation and foundation treatment work design of large

dams and other major hydraulic infrastructure projects • Experience in similar projects in other countries

• Familiarity with the national geological conditions and issues Geotechnical Engineer / borrow areas /Geologist (national)

• Expertise in large dams’ • Geotechnical investigation for borrow areas of large dams and other major

hydraulic infrastructure projects • Experience in similar projects in other countries

• Familiarity with the national geological conditions and issues Dam Operation & Maintenance Engineer (national)

• Having worked as dam operation and maintenance engineer in home country and outside.

• Expertise in maintenance of hydro-mechanical & electric equipment’s

• Familiarity of general O&M issues of large dams in the national and international environment


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Table 20. POE Overall Tentative Work Schedule Expert I N Man-week

1. Tender Preparation Phase: Q4 2019 to Q1 2020 Dam /Geotechnical Expert Seismologist Hydrologist/Sediment Specialist Hydraulics engineer Structural Expert Electro-mechanical Expert Geotechnical /Rock Mechanics / Grouting Expert Geotechnical / Dam Material / Borrow Area Expert

x x x x x x x x

x x x x x x x x

4 2/3 2/3 2/3 2/3 2/3 2/3 2/3

2. Construction stage: Q3 to Q4 2020 Dam /Geotechnical Expert Hydraulics engineer Structural Expert Electro-mechanical Expert Geotechnical /Rock Mechanics / Grouting Expert Geotechnical / Dam Material / Borrow Area Expert

x x x x x x

x x x x x x

2 2/3 2/3 2/3 2/3 2/3

3. Long-term operation Phase: Q2 2021 (Year 1) Dam /Geotechnical Expert Hydraulics engineer Structural Expert Electro-mechanical Expert Geotechnical /Rock Mechanics / Grouting Expert Geotechnical / Dam Material / Borrow Area Expert

x

x x x x x x

2 0/2 0/2 0/2 0/2 0/2

4. Long-term operation Phase: Q2 2022 (Year 2) Dam /Geotechnical Expert Hydraulics engineer Structural Expert Electro-mechanical Expert Geotechnical /Rock Mechanics / Grouting Expert Geotechnical / Dam Material / Borrow Area Expert

x

x x x x x x

2 0/2 0/2 0/2 0/2 0/2

Note: I = International; N = National Source: TRTA Consultants, 2019

IX. REFERENCES

Broderick, C., T. Matthews, R. L. Wilby, S. Bastola, and C. Murphy. 2016. Transferability of Hydrological Models and Ensemble Averaging Methods Between Contrasting Climatic Periods. Water Resources Research. 52, 8343–837.

CIDA. 2008. Arghandab Irrigation Rehabilitation Project, Technical Appraisal Mission Reports.

Favre, R., and Kamal, G.M. 2004. Watershed Atlas of Afghanistan: Afghanistan Information Management Service. Kabul, Afghanistan. 183 p.

GHD. 2011. Quipolly Dam, NSW, Australia.

Gibson, S. and Pridal, D. 2015. Negotiating Hydrologic Uncertainty in Long Term Reservoir Sediment Models: Simulating Arghandab Reservoir Deposition with HEC-RAS. SEDHyd: 10th Interagency Federal Sedimentation Conference.

Hunter. G. & Fell. R. 2003. The Deformation Behaviour of Embankment Dams. University of New South Wales, Sydney.

Delft Hydraulics and the Water Research Institute. 2005. Integrated Water Resources

Management for the Sistan Closed Inland Delta, Iran.

Morrison-Knudsen Afghanistan, Inc. 1956. Final Design Report on Kajakai Dam, Arghandab Dam

and Boghra Canal Projects. International Engineering Company.

Mort, O.D., Ambayec, R.R., and Haase, R.J. 1973. Hydrographic and Sedimentation Survey of

Arghandab Reservoir.

Mott MacDonald. 2014. Helmand River Basin, Master Plan.

NZSOLD. 2000. New Zealand Dam Safety Guidelines.

Pells. S. and Fell. R. 2002. Damaging and Cracking of Embankment Dams by Earthquakes and the Implications for Internal Erosion and Piping. UNICIV Report No. R-408. School of Environment and Civil Engineering, the University of New South Wales.

Seiller, G., F. Anctil, and C. Perrin. 2012. Multimodel Evaluation of Twenty Lumped Hydrological Models Under Contrasted Climate Conditions. Hydrology and Earth System Sciences. 16(4), 1171–1189

Seiller, G., I. Hajji, and F. Anctil. 2015. Improving the Temporal Transposability of Lumped Hydrological Models on Twenty Diversified U.S. Watersheds. Journal of Hydrology: Regional Studies. 3, 379–399.

Spencer, E.1967. A Method of Analysis of the Stability of Embankments Assuming Parallel

Interslice Forces. Geotechnique. 17: 11-26. and Wright, S. 1969. A Study of Slope Stability and

the Undrained Shear Strength of Clay Shales. Ph.D. Thesis, University of California, Berkley, California.

TRTA Consultants. 2017. Dam Safety Inspection Report.

TRTA Consultants. 2018. Hydrology Study Report.

TRTA Consultants. 2018. Multi Sector Water Allocation (MSWA) Report.

TRTA Consultants. 2018. Component 4: Hydropower Feasibility Report.

TRTA Consultants. 2018. Component 1: Dam Optimisation and Concept Design Report.

83

UN Population Fund. 2005. A Social-Economic and Demographic Profile of Kandahar Province, Afghanistan.

USACE 2011. Tetra Tech.

USACE. 2011. 3.7 Dahla Dam FS Appendix A Hydrology.

USACE. 2011. Arghandab Irrigation Rehabilitation Dahla Dam.

USACE. 2013. Dahla Dam Water Improvement Project – Focused Feasibility Study Report.

USACE. 2014. Geotechnical Report – Louis Berger Report.

USACE. 2014. Hydraulics Design Report.

USACE. 2016. Spillway Drawing Set.

USDA. 1997. National Engineering Handbook. Chapter 52.

USGS. 2006. Scientific Investigation Report 2006-5182. p. 26.

USGS. 2011. Dahla Seismic Write-up.

Williams-Sether, Tara. 2008. Streamflow characteristics of streams in the Helmand Basin, Afghanistan, Fact Sheet 2008-3059. U.S. Agency for International Development.

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APPENDIXES (ATTACHMENTS)

APPENDIX 1: FEASIBILITY COST ESTIMATES

APPENDIX 2: PROPOSED PROJECT SCHEDULE

APPENDIX 3: EWATER HYDROLOGY ASSESSMENT

APPENDIX 4: FEASIBILITY STUDY DRAWINGS

✓ FS-10-1 to 4: GENERAL: cover sheet, list of drawings, and project location ✓ FS-12-1 to 13: AS BUILT DRAWINGS (1952 DESIGN); ✓ FS-15-1 to 5: TOPOGRAPHY; ✓ FS-16-1: TYPICAL VILLAGE PROTECTION STRUCTURES; ✓ FS-17-1 - 10: AFFECTED VILLAGES PLAN - to be updated once information agreed with

affected people become available; ✓ FS-18-1 - 11: PROJECT GENERAL LAYOUT PLAN; ✓ FS-20-1: DIVERSION / COFFER DAM SPILLWAYS; ✓ FS-30-1 - 3: MAIN DAM; ✓ FS-31-1 - 2: SADDLE DAM 6; ✓ FS-32-1 - 4: SADDLE DAMS 1 - 5; ✓ FS-40-1 - 7: INTAKE TOWER, TRASHRACK AND OUTLET STRUCTURE; ✓ FS-50-1 - 6: SPILLWAYS; ✓ FS-60-1 - 9: RESERVOIR GEOLOGY; ✓ FS-70-1: ROUTE BEARER HIGHWAY, and ✓ FS-80-01: PARK.

APPENDIX 5: FEASIBILITY HYDRAULICS STUDY REPORT

APPENDIX 6: FEASIBILITY STRUCTURES ANALYSIS REPORT

APPENDIX 7: DOCUMENTS RECEIVED FOR STUDY

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PART B: ROUTE BEARER HIGHWAY REALIGNMENT

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I. INTRODUCTION

259. The Government of the Islamic Republic of Afghanistan requested the Asian Development Bank (ADB) for technical assistance to prepare an investment project to improve water resource management, irrigated agriculture, domestic and industrial water supply for Kandahar City, and to augment electric power in Kandahar City and surrounds. A transaction technical assistance (TRTA) to prepare the Arghandab Integrated Water Resources Development Investment Project was approved by ADB on 8 December 2016, with a Letter of Agreement approved by the Government on 17 January 2016. The Ministry of Energy and Water (MEW) is the lead counterpart agency supported by the Ministry of Agriculture, Irrigation and Livestock (MAIL) for the irrigation and agriculture component.

260. The proposed program of investment in total aims to improve water availability, efficient management of water resources, and improve water productivity in agriculture. The investment project is to be located in the Arghandab River sub-basin, a significant tributary of the Helmand River system. The program of investment is envisaged to comprise four components in two or three loan projects:

(i) Component 1: Raising Dahla Dam and six saddle dams; (ii) Component 2: Climate-resilient productive use of water in agriculture; (iii) Component 3: Kandahar municipal and industrial water supply; and (iv) Component 4: Dahla Dam hydroelectric power development.

261. The Government of the Islamic Republic of Afghanistan has accepted TRTA’s recommendation for a dam raise of 13.6 m, which provides an additional 500 million m3 water to Dahla reservoir with a water head of 58.75 m at Full Supply Level giving a hydropower potential of 28.5 MW and allows a buffer storage to maximize water storage for later release as per downstream requirement. The proposed dam raise requires realignment of the existing Route Bearer Highway.

262. The proposed raise requires realignment of a section of the existing Route Bearer Highway also known as Kandahar-Bamiyan Highway in Shah Wali Kot District of Kandahar. Kandahar Ministry of Public Works (MPW) with Public Works Authority manages the existing highway.

263. This feasibility design report covers Route Bearer Highway realignment of the proposed integrated water resources investment subproject Component 1.

264. In accordance with the Terms of Reference this report presents a tender level design of Route Bearer Highway, as well as initiatives to address the constraints and risks that affect proposed realignment. The project design is based on assessment of the situation, issues and priorities of stakeholders, and careful selection of viable, affordable options, estimating capital and operational costs, for which investment is justified. Specifications are presented in Appendix 10 and feasibility-level drawings for civil works are presented in Appendix 11.

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II. EXISTING ROUTE BEARER HIGHWAY

A. Overview of the Transportation Sector

265. The main road network in Afghanistan comprises 3,227 km of Regional Highways (international corridors), 4,906 km of National Highways, and 8,959 km of Provincial Roads. The remaining rural road network consists of village access roads of about 17,000 km.

266. Providing a good road network is very essential for the development of any country. In Afghanistan, there are about 40,000 villages located in different terrain conditions (e.g., plain, hilly and mountainous regions, deserts, etc.). The climate conditions also vary from place to place to an extent. Social, economic and educational developments of these villages greatly depend on accessibility. A large number of villages in rural Afghanistan are isolated from all-weather roads. The employment opportunities and necessities like, health, education, and social welfare cannot reach rural masses without a systematic and coordinated road network. The prolonged conflict had denied most of the rural population access to essential social services like markets, health centers, schools and government administrative offices.

267. The main challenges facing the roads O&M in Afghanistan are related to institutional sustainability. Financially, Afghanistan is not expected to be self-reliant over the next decade. Funding requirement for the roads O&M is estimated upwards of $200 million annually, while the Ministry of Finance (MOF) only disburses $23 million annually, out of $83 million collected through roadway user fees and taxes, for the roads O&M. Institutionally, the challenges include organizational and human resource issues. Organizationally, the mandates of the different organizations responsible for roads need to be properly delineated. Functionally, the Ministry of Public Works (MPW) lacks the specialized support systems required for adequate and accountable operations. A tool for planning and management roads O&M at the national level is virtually non-existent.40

268. MPW is typically responsible to execute design, survey, construction and rehabilitation of roads / Highways, regional roads, link road and provincial roads, road maintenance, contracting for road construction with private sectors / road companies, monitoring from planning of rail ways, road and bridge restoration.

269. Theoretically, MPW has 15 departments, of which five have administrative functions, four are for technical planning, and six are operational, involving construction and maintenance of roads, airports, housing, and water supply. At least three of the operational departments are state owned construction enterprises previously engaged in construction of roads, airports, commercial and industrial buildings, and housing. MPW is headed by a Minister, assisted by two deputy ministers and three advisers. Most of MPW’s more than 6,000 staff are ill-equipped to perform their duties, hence MPW finds it difficult to carry out its responsibilities.

B. Existing Route Bearer Highway

270. The existing Route Bearer Highway, also known as Kandahar-Bamiyan Highway is in Shah Wali Kot District of Kandahar. The figure below shows in Google Maps Kandahar city, Dahla Dam and the highway.

40 ADB Draft Project Administration Manual, 2016, Project Number - 50062-001

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Figure 10. Existing Route Bearer Highway

Source: Google Maps, 2019

89

271. Existing Route Bearer is a two-lane single carriage highway. The highway is 7.3 m wide of paved area and has 1.5 m shoulders on both sides. Existing alignment passes mainly along barren hilly areas with limited or no inhabitant adjacent to it. Shahjuy is the only village in this stretch.

Figure 11. Photo of the Existing Route Bearer Highway


272. No drains exist along the existing route and water flow naturally along the road embankment in natural topography. No embankment damage was noted due to non-availability of drains along the route. There are number of culverts and one existing causeway. Several of the existing culverts were destroyed using Explosive ordinance attacks.

273. Kandahar MPW with Public Works Authority manages the existing highway.

274. The Kandahar-Bamiyan Highway is an important key link for the villages in the region. Dahla Dam raise should bring significant economic growth opportunities for the Shah Wali Kot district and in particular Kandahar region.

275. It is anticipated that in the future, once peace will be restored in the region, Route Bearer Highway should be a key route for iron ore transport through Gwadar Port in Pakistan to international market. Indeed, the Ministry of Mines and Industries indicated three major areas where large scale mining and industrial development is expected in the short to medium term. These are Aynak copper mines in Logar province, Dara-i-suf coal mines in Samangan Province and Iron ore deposit in Bamyan province.41

41 ADB TA No. 4371-AFG Master Plan for Road Network Improvement Project (Master Plan Component) Draft Final

Report, November 2005

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C. Key Issues

276. There are two existing stretches of Route Bearer Highway. One is the old highway existing with the dam and the other stretch is a 4.3 km long highway stretch realigned and raised to accommodate the previously scheduled 8 m dam raise. During the present feasibility studies, it was noted that about 6 km reach would be inundated even for the case of 8 m raise. As such, this stretch also requires realignment and upgrade for safe travel of road users.

277. It was also observed that number of existing culverts along the highway were destroyed. Most of these damaged culverts were noted to be unrepaired and non-functional and may lead to high risk of flooding of the area. Damaged culverts along existing route should be repaired to mitigate risk of flooding area between existing and re-routed highway.

Figure 12. Photo of a Destroyed Culvert


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III. PROPOSED ROUTE BEARER HIGHWAY REALIGNMENT

A. Approach and Methodology

278. The proposed alignment was considered based on the following factors:

Safe travel for road users even in case of Dam Crest Flood (i.e. above 1154.0 m); Development of regional economic activities; Improvement of the living environment of citizens; Possibility for dual carriage way; Possibility of future extension to motorway; Minimum cut and fill or balance cut and fill; and Minimal effect on commute distance and travel time for users.

279. The design reflects and encompasses the priorities of MEW as expressed in the Afghanistan National Development Strategy (2007). The design is aligned with the Water Law (2009), which formalized the adoption of integrated water resources management principles within national water sector policies and sector strategies of MEW, MAIL, Ministry of Rural Rehabilitation and Development (MRRD), Ministry of Urban Development and Housing, Ministry of Mines, Ministry of Public Health, and NEPA which all have direct mandates in the water sector. It also reflects the priorities of Arghandab Sub-basin Authority (ASBA).

280. The proposed alignment design was considered based on number of issues like all time safe travel for road users even in case of Dam Crest Flood i.e. above 1154,0 m (WGS 84 elevation), possibility of future extension to motorway, possibility for dual carriage way, minimum cut and fill or balance cut and fill, minimal effect on commute distance and travel time for users.

281. Existing highway alignment was also assessed for only raising of the road by using additional fill. However, it was noted that existing road embankment at some reaches was raised up to 10 m with fill. Such an embankment with more filling may have slope stability concerns due to likely piping and washing of fines from the embankment with reservoir water fluctuation. Due to culverts at low level, both sides of the road would then be under water. It was considered that the Route Bearer Highway may need further widening in coming years which was not possible for a raised embankment. Therefore, it was decided to design a revised route alignment.

282. The design has been performed to optimize cut and fill. This should minimize wastage and disposal issues. The unusable material will be disposed in approved landfills of NEPA along downstream of the Main Dahla dam to ensure that the excavated does not interfere with existing streams or water ways.

283. A meeting was held on 23 November 2018 in MPW’s Kandahar office. TRTA requested MPW to provide existing traffic and design data for Route Bearer Highway. It was observed that MPW team was new and competent. However, due to security situation in the area, relevant data for the area were not available.

284. The approach of the present tender design was:

Perform a topographic survey along the existing highway route. This included horizontal and vertical profile of the 8 m raised and highway length to be flooded for the dam raise. A length of about 11 km was surveyed. The survey team took number of pictures and videos along the existing route. The survey took x-sections at every 25 m interval. The x-sections covered 50 m width from centerline of the road.

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Review and assessment of the performed topographic survey for the adequacy of the existing highway for the dam raise;

Use the performed topographic survey for the reservoir to select a possible alignment which is economical in the long run and offers flexibility and ease to road users;

Prepare the tender design drawings (Appendix 11), project schedule (Appendix 8) and cost estimates (Appendix 9) as per AASHTO standards; and

Prepare design report (Part B) and tender specifications (Appendix 10).

B. Proposed Route Bearer Highway Realignment

285. The dam crest being raised to 1154 m, a realignment of the road above 1154 m is required. The proposed realignment is consistent with this 13.6 m spillway raise. The Figure below shows the proposed realigned highway and existing highway with the 13.6 m raise at dam crest flood and at full supply elevation.

Figure 13. Proposed Highway Realignment


286. A stretch of about 10 km requires realignment due to proposed 13.6 m spillway raise. The proposed realigned highway will be 9.3 km long and passes mostly through barren hilly terrain. This includes 850 m stretch of existing highway for rehabilitation / repair. The new construction will be limited to about 8.45 km.

287. 23 culverts and 2 super passages (causeways) are proposed along the route. It was noted that number of existing culverts were destroyed and due to security risks, it was preferred to defer design of bridge along the super passage. However, in future once peace will be restored in the area, the super passage number 2 should preferably be replaced with a bridge.

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288. It shall be noted that a 4.3 km long highway stretch was raised in 2016 for the highway to accommodate 8 m dam raise. However, there was significant reach which was not designed and upgraded for safe travel for the road users. This risk has been mitigated in the present design.

289. The Figure below presents the old 1952 highway, the 2016 8 m raised highway and the proposed realigned route.

Figure 14. Existing and Proposed Route Bearer Highway Alignments

Note: blue: 1952 highway, green: 2016 realignment for 8 m raise, red: 2019 proposed realignment for 13.6 m raise. Source: TRTA Consultants, 2019

290. Realignment of the road is mainly in an area with little or no effect on existing villages. However, there will be issues such as environmental management, accident management, construction waste disposal, resettlement and maintenance for the road.

C. Key Issues for Consideration Prior Construction

1. Resettlement

291. The proposed alignment from Chainage 4+600 to 5+200 i.e. 600 m long, will pass through Shahjuy village agriculture land. The Right-of-way (ROW) has been considered as 50 m from centerline. Considering the proposed ROW, a land of 30,000 m2 will need to be obtained for this highway. This land has already been considered under resettlement due to reservoir / dam raise and no additional land acquisition will be required. However, in order to start realignment works, the concerned land has to be acquired. Land acquisition will be a critical activity before the start of construction of the highway.

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292. The Resettlement surveys are underway, and the Land Acquisition and Resettlement Plan will be prepared in April 2019. Land acquisition will be a critical activity before the start of construction of the highway.

2. Landmines and Security

293. Afghanistan has more landmines than any other nation, and one difficult challenge has been clearing the highway and surrounding areas. Topographic survey along the proposed highway route had been performed successfully by the TRTA in 2018. Although no landmines were noted along the route, the contractor must ensure that the site is clear from landmines in close consultation with the relevant agencies. Previously air samples from the sites were collected and sent to labs, where mine detection dogs identified high-priority areas for de-miners. It is anticipated that the route alignment will be inspected carefully for this aspect.

294. It shall be the responsibility of the contractor to confirm that the technical survey/clearance of landmines/UXOs in the 25 m wide land strip on both sides of the centerline of the road and over the total length of the section has been properly achieved or not. If it is not yet completed for any given section, the Contractor shall request the Afghanistan Mine Action Centre (AMAC) Kandahar in due course to complete the remaining demining works for such section. In addition, the Contractor shall also submit requests to AMAC Kandahar for any additional survey/clearance of landmines/UXOs whenever and wherever it is deemed necessary for the safe conduct of his works.

295. The security threat due to the conflict situation is considered a major element contributing to increasing the cost of road construction. The cost of security can represent up to 15% of the total expenses of a road construction.42

296. Before the start of the earthworks, contractor will make a detailed topographic survey along the proposed highway alignment. The survey will include as a minimum 100 m stretch from the proposed road centerline on both sides of the road.

297. Contractor will prepare detailed construction drawings, update locations and numbers of the drainage structures, if required and approved, and prepare detailed cost estimate for the approval of the engineer.

3. Construction Materials and Machinery

298. Another factor contributing to the high cost of road construction is the import of construction materials and equipment from distant places rather than regional markets, sometimes due to strict deadlines or political considerations. The unit cost, at the biding level, for materials in Afghanistan is higher than Central Asia and Pakistan. The low level of quality materials available in Afghanistan, due to the post-conflict economic settings, is a pretext for exportation abuses even for basic materials. For example, USAID is prohibited from importing liquid asphalt from Iran but may import the material from Egypt. In another example, a World Bank financed project, the asphalt was imported from Turkey.43

299. The poor quality of the material used has serious implications for the sustainability of the road maintenance. In most of the district roads, companies have used Double Basement Surface

42 World Bank, W.Byrd, Managing Public Finance for development, Volume IV, December 2005, p.107 43 World Bank Ibib,

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Treatment (DBST), whose life expectancy is not more than three years. With the use of asphalt, the life expectancy of the road could reach 15 years.44

300. There will be need for stockpiling and processing / screening of the excavated and borrow material. Borrow fill would be available from existing reservoir area. This may be performed at location downstream of the Saddle Dam 6 where previous contractors made their site offices.

301. Asphalt is likely to be imported from Quetta Pakistan, about 200 km from Kandahar or Iran. Stone and rock could be easily available from Kandahar.

302. Construction plant and equipment, including a crushing plant, asphalt plant, grader, rollers, and dump trucks are expected to be imported from neighboring countries such as Pakistan or Iran.

4. Road Maintenance

303. Proper management of roads is essential to ensure the roads, once completed, would perform the expected functions for years to come. The road maintenance consists of routine maintenance, periodic maintenance and emergency maintenance.

304. Routine and periodic maintenance of road facilities would result in costs lower than the case of rehabilitation after long neglect. Maintenance works are required once road projects are completed. It is important that maintenance works for road facilities should start upon project completion to keep them in good conditions. The maintenance for existing road facilities should also be carried out as there are many poorly maintained infrastructures. Regular inspection or inventory survey for road facilities and development of the system for stock database are important to realize well-maintained road infrastructure at all time. These actions would help to make balance between new road development and maintenance of existing facilities, allowing easy specification of road projects.

305. There are two kinds of implementation methods for road maintenance works: (i) direct works conducted by road administration; and (ii) subcontracting.

306. Subcontracting is generally preferred to direct works for cost effectiveness. This, however, is pre-conditioned that the relevant road administration has skills and experience to manage the sub-contracted works. Also, the administration should undertake the minimum repair works as necessary.

307. Summary of Maintenance works are provided in the Table below.

Table 21. Summary of Maintenance Works Category Contents Interval Initial cost

Routine maintenance

✓ Patrol and inspection ✓ Surface, Drains / Culverts cleaning ✓ Pothole repairs ✓ Small damage repair of facilities ✓ Water sprinkling for surface and Plants litter removal, etc.

Weekly / 1 year

Small

Periodic maintenance

✓ Repaint, resealing for road Facilities ✓ Asphalt overlaying ✓ Rehabilitation activities such as road-base etc.

5-10 years Large

Emergency repairs

All that is necessary As necessary (disaster)

Small to Large


44 Afghan roads reconstruction: deconstruction of a lucrative assistance, 2007, www.tiri.org

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IV. DESIGN CONSIDERATIONS

A. Guidelines

308. The design has been based on AASHTO’s guidelines and on the Interim Road and Highway standard of Afghanistan established by MPW in January 2005. In 2013, MRRD Afghanistan also issued Version 2 of the Afghanistan Rural Road Manual. However, this is a temporary working document that will be updated subsequently.

309. Due to security situation in the area, there was very limited data available with the local authorities.

B. Climate and Rainfall

310. The annual average temperature in Kandahar is 18.8 °C. The hottest month is July with average temperatures of 31.8 °C. January shows the lowest temperature with an average of 5.7 °C. All over Kandahar Province, the summer heat is intense, and the simoom (hot dust storms) and fiery winds, which frequently occur throughout this part of the country during the hot season, make life difficult. At the same time, the bare rocky ridges that traverse the country, absorbing heat by day and radiating it by night, render the summer nights almost as hot.

311. Kandahar is a desert climate (BWh classification according to Köppen and Geiger), and precipitation is low. While annual average rainfall is 176 mm, the evaporation figure is just over ten times that.45 Mean Annual rainfall pattern is presented in the Figure below.

Figure 15. Mean annual rainfall pattern in Kandahar

Source: www.weather-and-climate.com

312. Raining intensity-duration curve for Kandahar was developed based on average from Farah and Ghazni provinces.46 These curves were developed for a 1 in 10 year AEP (annual exceedance probability) event.

45 Michel. 1957. The Kabul, Kunduz, and Helmand Valleys and the National Economy of Afghanistan: A Study of

Regional Resources and the Comparative Advantages of Development. National Academy of Sciences, USA. 46 USACE Route Bearer Highway Relocation Hydrological Study (2015)

http://www.weather-and-climate.com/

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Figure 16. Ten Year Rainfall Intensity-Duration Frequency Curves

Source: USACE Route Bearer Highway Relocation Hydrological Study, 2015

C. Hydrology and Drainage

313. Hydrology study was done during the TRTA using 2018 imagery of the project previous USACE work.

314. There are various small to medium streams which bring rain water to the dam site. Typically, these stream flows are quick and develop rapidly. Most stream remain dry during most of the time of the year. Usually rains in the region are limited from July to December.

315. 23 culverts and 2 causeways were proposed along the realigned route. The structures were sized to pass the 10-year precipitation event. Criteria outlined by the Unified Facilities Criteria (UFC, 2004) were used to determine potential drainage structure sizes. Inlet control was used to design the culverts as terrain is steep (~2%) and culvert lengths were assumed short (< 200 ft).

316. Table 2 below provides a summary of design parameters. Only circular concrete culverts were considered. Two sizes of pipes were used for the culverts. These were 610 mm and 910 mm. At least 0.9 m of ground cover was required above the structure, and design assumed passing flows with 0.3 m freeboard of road.

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Table 22. Structure type, location and design details Serial

Number

Structure

Number

Chainage Structure

Type

Number

of pipes

Pipe

length

(m)

Total pipe length required (m) 610 mm pipe

diameter 910 mm pipe

diameter

1 1 1+010 Circular Culvert 1 15 15 2 2 1+275 Circular Culvert 1 15 15 3 3 1+600 Circular Culvert 2 15 30 4 4 1+800 Circular Culvert 3 15 45 5 5 1+950 Circular Culvert 2 20 40 6 6 2+570 Circular Culvert 1 20 20 7 7 2+950 Circular Culvert 3 20 60 8 8 3+150 Circular Culvert 3 25 75 9 1 3+450 Causeway #1 6 15 90 10 9 4+600 Circular Culvert 2 15 30 11 2 5+250 Causeway #2 12 15 180 12 10 5+750 Circular Culvert 2 15 30 13 11 5+651 Circular Culvert 2 15 30 14 12 6+460 Circular Culvert 1 15 15 15 13 6+675 Circular Culvert 2 15 30 16 14 6+900 Circular Culvert 2 15 30 17 15 7+550 Circular Culvert 2 15 30 18 16 7+700 Circular Culvert 2 15 30 19 17 8+150 Circular Culvert 2 15 30 20 18 8+425 Circular Culvert 2 15 30 21 19 8+600 Circular Culvert 2 15 30 22 20 8+825 Circular Culvert 1 15 15 23 21 8+875 Circular Culvert 1 15 15 24 22 9+100 Circular Culvert 2 15 30 25 23 1+022 Circular Culvert 2 15 30 TOTAL 470 505


D. Topography and Vegetation

317. Mountains, with an elevation of about 1,200 to 2,800 meters above sea level (MASL), dominate the northern and the eastern parts of the province. On the other hand, the southern and the western parts of the province are dominated by desert with an elevation of about 1,000 MASL.

318. The topography of the project site includes bare mountains without vegetation and the flood plain of Arghandab River. Elevations of the mountains are up to 1,300 MASL. Highlands below the dam have very scarce vegetation (elevation: 1,120 – 1,140 MASL). The Arghandab River valley begins at 1,200 MASL at Dahla Dam and the elevation below Kandahar is below 1,000.

319. The terrain along the realigned Route Bearer is mainly hilly with some mountains and dissected by numerous gullies and at least two river valleys. The realigned road crosses Shahjuy Village near 4+600 m chainage. Then the road passes through agriculture land of the village. The typical elevations of the mountains are in the range of 1100−1170 MASL.

320. Generally, the hills and mountains are barren with limited vegetation. However, Shahjuy village has good agriculture land along the route. The fertile top soil from the area may be removed and stockpiled for construction of a re-creational facility like a ground / park downstream of the dam site.

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E. Geology and Soils

321. Previously, Louis Berger and later TRTA consultants performed limited geotechnical investigations along the existing highway and it was anticipated that a CBR of 15 should be available along the realigned highway. It was also anticipated that the borrow area fill from the reservoir site, should be of high strength and offer a minimum CBR of 15 for the pavement design.

322. Project area geology is presented in the Figure below.

Figure 17. Geology along the Proposed Route Bearer Highway Alignment

Source: Map modified from: O’Leary, D.W. and Whitney, J.W. 2005, Geological map of quadrangle 3164, Lashkargah (605) and Kandahar (606) quadrangles, Afghanistan, USGS 1:250,000 Geological map Note: the black square represents the location of the Component 1 work site. The red line gives a brief approximation of the realigned route path.

323. Generally, the re-routed alignment follows hills with various geological formations. Adjacent to the dam site, it passes through P23rl formation. This formation is high strength Rhyolite lava (Oligeocene and Eocene). Rhyolite lava is more abundant than basaltic andesite, basalt, trachyte, dacite, ignimite, tuff, conglomerate, sandstone, siltstone and limestone. This formation comprises high to very high strength rocks. Such rocks are difficult to excavate and typically offer California Bearing Ratio (CBR) of over 30. Pavement thickness may be optimized along these formations.

324. After the dam site, the re-routed alignment follows hills with shale and siltstone called J3K1sh formation. Shahjuy village also comes under this formation. This formation offers fertile soil. Shale is more abundant in the area as compared to siltstone, sandstone, conglomerate, cherrt, limestone, greenstone, acid and mafic volcanic rocks. These are medium to high strength rocks. Such rocks are moderate to difficult in excavation and typically offer CBR of over 20. Pavement thickness may be optimized at such places. Excavation along this formation should provide common fill that could be used for embankment formation.

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325. After the Shahjuy village, the re-routed highway crosses an existing stream and then crosses strong rock formation called Grandiorite (Oligocene) P3gd formation. These rocks also exist along the downstream of the existing dam. These rocks are high to very high strength, difficult to excavate and typically require drilling and blasting. Such rocks typically offer CBR of over 20. Pavement thickness may be optimized at such places. The excavated rock along this reach should provide high quality basecourse and sub-base course for the road.

326. It is mandatory that Contractor will perform geotechnical investigations along the route and re-estimate the CBR for various soil / rock formations. The Contractor will make test pits at every 100 m stretch and report the findings to the engineer before the start of the earthworks. Should the CBR along the route is validated to be high then the pavement design may be further optimized to reduce the cost of the pavement works. The Contractor will also make tests pits along existing Route Bearer Highway and report the pavement thickness details to the Engineer. The test pits will follow with grain size distribution, Insitu density and CBR testing at each test pit. Every test pit will be recoded and sufficiently detailed pictures with scale in mm will be placed before taking pictures of every pavement layer. The contractor will then provide a geotechnical report to the engineer with the assessment of the existing pavement and proposed pavement design for approval.

327. Similarly, the route should also be further assessed for reducing rock excavation where possible and replacing with borrow fill embankment.

F. Road Classification

328. As per Interim Road and Highway Standard, 2005, MPW, roads are categorized from the viewpoints of road functions and road design. Functional classification is divided into five categories from major roads to community roads. Design classification has five categories including expressways based on Afghan standards as presented in the table below.

Table 23. Road Design Standard of Afghanistan Afghan standard ROW

(m) Average Daily Traffic

(PCU/day) Design speed*

(km/h) Lanes

(n) Expressway Type 2 100 > 30,000 120 / 100 / 80 > 4 Expressway Type 1 50 13,000 - 30,000 120 / 100 / 80 4

Major road

30 (Rural) 5,000 - 13,000

100 / 80 / 50

2

19 (Urban) Minor road

30 (Rural)

< 5,000

60 / 50 / 40

2 18 (Urban)

PCU = Passenger Car Unit * Design speed: Flat / Rolling / Mountainous terrain Source: MPW, Interim Road and Highway Standard, 2005

329. The relationship between the road classification and the area of service is given in the table below.

Table 24. Relationships between Functional Classification and Design Classes Functional classification Area specification

Rural Urban

Expressway S S Major arterial I or II I or II Arterial II or III III or IV Secondary III or IV III or IV Community IV IV Source: MPW , Interim Road and Highway Standard, 2005

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330. Route Bearer Highway can be classified as Major Road (Rural) with an average 5,000 to 13,000 Passenger Car Unit (PCU)/day. Such a road is defined to have two lanes (2x3.65 m) with 1.5 m paved / gravel shoulder. Typical design speeds for such roads are considered from 50 to 100 km/h depending on flat, rolling and Mountainous terrain. A design speed of 80 km was taken. This could be considered under Area Specification as Arterial Rural II or III.

G. Design Criteria

331. Traffic Estimation: An average 5,000 to 13,000 PCU/day is defined as per Interim Road and Highway Standard, 2005, MPW. Such roads are defined to be paved Asphalt Concrete road.47 It is mandatory to perform traffic count survey along the proposed realigned portion of the highway. The pavement design then may be revisited if necessary.

332. Right-of-way (ROW): Consideration of ROW in Afghanistan is provided in the road design standards. The ROW may be determined according to the functional classification of roads as shown in the tables above. Provision is made for spaces for utilities, reserve for extra lanes corresponding to future traffic demand or public transport corridor. For the Route Bearer Highway considering 2 lanes, a 50 m ROW has been considered.

333. Carriageway: The road has been designed as single carriage dual lane road. Lane width has been considered as 3.65 with 7.3 m for two lanes and shoulders as 1.5 m on each side.

334. Typical cross sections: A typical cross section of road has been prepared based on the design criteria presented above and presented in tender design drawings (Appendix 11).

335. Outline of realigned portion: The Table below presents the outline for the realigned part of the Route Bearer Highway.

Table 25. Outline of Realignment of part of Route Bearer Highway Development

Design class Design speed

(km/h) Length

(km) ROW (m)

Road width (m)

Lanes (n)

Major Road (Rural) 80 9.3 50 7.3 + 2x1.5 = 10.3 m 2 Source: TRTA Consultants, 2019

336. Geometric Standards: The Table below presents the geometric standards for a design speed of 80 km/h.

Table 26. Geometric Standards Minimum Radius of Curve (m) Desirable 200

Standard 150 Absolute 120

Minimum Radius for Vertical Curve (m) Desirable Crest 2,000 Sag 1,500

Standard Crest 1,400 Sag 1,000

Minimum Length for Vertical Curve (m) 50

Maximum Grade (%) Desirable 5 Source: MPW , Interim Road and Highway Standard, 2005

47 ADB TA No. 4371-AFG Master Plan for Road Network Improvement Project (Master Plan Component) Draft Final

Report, November 2005, page 44

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H. Pavement Design

337. The pavement design has been performed using AASHTO Design Guide 1993. The essential parameters considered in calculating the pavement thickness consist of the following factors:

Traffic conditions; Reliability; Environmental impacts;

Serviceability; Pavement layer materials properties; Design coefficient; FDD of the existing sub grade in case of reconditioning; CBR of sub grade.

338. Axle loads: The Axle loads factors used for the calculation of Equivalent Standard Axle Loads (ESALs) are: (i) Bus: 0.99; (ii) Tractor: 1.19; and (iii) Truck: 6.49.

339. Equivalent Standard Axle Loads (ESALs) Estimation: Is provided in the Table below.

Table 27. ESAL Estimation

Vehicle Type

ADT Annual Traffic

Growth Rate %

Growth Factor

Total Traffic for

design life

ESA Factor ESAL

Loaded Empty

Buses 8 2920 5 22 63,009 0.897 56519.43689 Tractor Trolly 12 4380 5 22 94,514 0.881 0.036 83266.9296 Trucks 2XL 12 4380 4 20 87,703 3.705 0.075 324940.7778 Trucks 3XL 2 730 2 17 12,624 5.813 0.047 73384.44175 Trucks 4XL 2 730 2 17 12,624 7.627 0.385 96284.7303

Total 13140 Total 634,396.32

Design Life 15 Enter Life here 0.634396316

Road type Rural Principal Arterial ESAL by taking 100 % of directional factor 634396.3 0.634396316

ESAL by taking 80 % lane factor 507517.1 0.507517053

ESAL by taking 50 % lane factor 317198.2 0.317198158 ADT = average daily traffic at the start of the design period, in number of vehicles per day; T = percentage of traffic in the ADT consisting of trucks; Tf = truck factor; D = direction distribution (0.5 if amount of traffic is the same in each direction); G = growth factor; D = direction distribution (0.5 if amount of traffic is the same in each direction); L = lane distribution factor; Y = design life, or analysis period, in years. Note: ESAL = (ADT) x T x Tf x D x G x L x 365 x Y; G= (1+r) ^ (0.5) Source: TRTA Consultants, 2019

340. Pavement design is presented in the Table below. Selected pavement section and design is presented in Tender drawing No: RB-20-01.

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Table 28. Pavement Design 1 Design life years 15 2 Standard axle (legal limit) kips 18 3 Traffic Growth Rate (i) Buses 6%

(ii) Trucks 4%

4 Number of Equivalent Standard axles (Zr = -1.645)

ESAL 0.317198

5 Reliability Level R 85% 6 Standard Deviation So 0.45 7 Initial Serviceability Po 4.2 8 Terminal Serviceability Pt 2.5 9 Over all serviceability loss 1.7

10 CBR (Sub grade-soaked) 15% 11 Resilient modulus Mr (psi) 22,500 (1,500 x CBR) 12 Layer Coefficient for new structure

AWC a1 0.173 /cm

AsBC a2 0.157 /cm ABC a3 0.055 /cm GSB a4 0.043 /cm 13 Drainage Coefficient for Aggregate Base 1 14 Drainage Coefficient for Sub Base 1 15 Resilient Modulus

AWC EAC-1 Psi 450,000 AsBC EAC-2 Psi 350,000 ABC Ebs Psi 30,000 GSB Esb Psi 30,000

16 THICKNESS OF PAVEMENT STRUCTURE Layer Layer coefficient Drainage

coefficient Layer

thickness (cm)

WSN Achieved

Accumulated

Design SN

AWC 0.173 5 0.865 0.865 AsBC 0.157 10 1.57 2.435 ABC 0.055 1 15 0.825 3.26 GSB 0.043 1 15 0.645 3.905 4.6

17 Recommended Pavement design thickness AWC cm 5 AsBC cm 10 ABC cm 15 GSB cm 15

AWC = Asphalt Wearing Course; AsBC = Asphalt Base Course; ABC = Aggregate Base Course; GSB = Granular Sub Base Source: TRTA Consultants, 2019

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V. PROPOSED PROJECT OUTLINE

A. Outcome, Outputs and Activities

341. The overall outcome will be realignment of the Route Bearer Highway contributing to improved travel facility and rural economic growth. This outcome is based on the full integrated water resources investment project of raising the dam, irrigated agriculture, urban and peri-urban water supply, and hydropower.

342. This outcome will be supported by following 4 outputs:

Output 1: Earth Work; Output 2: Sub-base, Base Course and Wearing Course; Output 3: RCC Culverts and Causeways; and Output 4: Ancillary Works.

343. Output 1 to 4 will all involve the following activities;

Mobilization and demobilization of contractor’s camp, soil testing laboratory and facility. It is suggested that the space used previously downstream of Saddle dam 6 be used for construction camp in close consultation with ASBA and MEW.

Security and location of the Explosive ordinance along the proposed route will have to be considered before construction to avoid any loss of life. Contractor has to coordinate with provincial authorities such as AMAC to ensure that the proposed route is safe from underground mines.

Detailed topographic survey along the proposed route will need to be performed before construction. The topographic survey should include x-section survey at every 10 m with up to 50 m from centerline and form the basis for all earth works and pavement works estimation and payment. The contractor shall prepare detailed construction drawings and may present alternative economical pavement and structural design for the approval of the engineer.

Additional geotechnical investigations survey along the proposed route will need to be performed before construction. The investigations will help assessment of the highway cuts and filling works and bearing capacity along proposed culverts and super passages.

Traffic Management along the existing road. A temporary road will be required to divert traffic during works along existing road;

Although rain is not a critical factor, all works in existing streams should consider suitable measures to manage water. Particularly location of super passage will need careful considerations.

344. Output 1 and 2 will involve the following additional activities:

Asphalt paved road construction works which will include 8.5 km long new and about 850 m existing stretch raise works.

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Construction works will include excavation, cutting, filling, pavement and structural works. The excavation works are likely to involve limited drilling and blasting and hammering to remove rockfill over consolidated material along the route and stockpiling for subsequent use as base / sub-base and embankment fill where possible. Similarly, there will be stockpiling requirement for the excavated rockfill and general fill to be reused as embankment fill.

Filling works should involve re-use of excavated general and rockfill materials where possible. Base and sub-base should be available from excavation along the realigned Route Bearer after 5+000 chainage.

Additional common borrow fill for the road works should be available from nearby reservoir area along existing Route Bearer Highway. The possible quarries for the sandy gravel fill for embankment construction are inside the Dahla Reservoir adjacent to existing Route Bearer Highway within reservoir area. These quarries must be approved by NEPA, ASBA, MEW and local Authorities.

As the road passes through agriculture land, it is proposed that topsoil up to 0.6 m depth or more in the agriculture land reach may be stockpiled separately for subsequent use of this soil for community recreational works in future. This will also require removal of fruit and other trees from the area. These trees can be re-planted, or the owners may be allowed to remove these trees for future use.

345. Output 2 will involve the following activities:

Pavement works will be performed after the road surface has been prepared as per approval of the Engineer.

All asphalt concrete works and availability of cement and gravels will have to be planned to ensure timely availability during construction. Asphalt availability and planning will be a critical activity and should be planned before to avoid unnecessary delays. Various grades of Asphalt and in particular 60-70 should be available from Quetta, Pakistan. Performance Grade Penetration Grade Modified / Unmodified 58-22 80-100 Attock Refinery, Rawalpindi 64-25 60-70 National Refinery, Karachi 58-22 60-70 Uzbekistan Refinery 64-22 60-70 Unit Arab Emirates Refinery 70-22 60-70 Attock Refinery.

Rawalpindi Modified with 1.7% Elvaloy

For the aggregate sub-base and base course quarries has to be as per approval of

NEPA, ASBA, MEW and local Authorities.


Construction of 23 culverts and 2 causeways along the re-routed highway. The proposed culverts will be 610 mm and 910 mm RCC pipes as per AASHTO

standard. This will require contractor to arrange all the pipes as per project requirements.

Locations of all culverts and orientation shall be finalized as per site conditions and approved by the engineer. The Contractor will submit a design for approval of the

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engineer. Once finalized, structural excavations will be performed as per drawings or as approved by the engineer.

The Contractor may however, present an alternative design of the culverts to suite local conditions. No additional payment, however, will be admissible to the Contractor. The design and construction of the alternate structure must be consistent with project design requirements and has to be approved by the Engineer. The Contractor’s design must prove that the proposed design has equal or more flow capacity for the culverts.


Installation of the road signs, km stones etc., as required and approved by the engineer.

Any other work approved by the engineer for the successful delivery of the road works.

B. Cost Estimates

348. The cost estimate is based upon the quantities of different items of work resulting from detailed engineering design of the road structure components.

349. The rates applied are Composite Schedule Rates (CSR) of National Highway Authority (NHA) Pakistan for city of Quetta, Baluchistan CSR-2014 plus 30% for road work. Considering exchange rate, a factor of 2.25 was subsequently multiplied.

350. Estimated base cost for project activities is $16.361 million. The cost with 10 % security, 15 % contingency and 2% detailed design, project management and supervision is $20.778 million. Cost breakdown is presented in the table below and in details in Appendix 8.

Table 29. Project Cost Estimates Output Indicative Cost

($’ 000) Output 1: Earth work 6,512 Output 2: Sub-base, Base course and Surface course Output 3: RCC Culverts and Causeways Output 4: Ancillary works

8,714 901 234

Subtotal base cost 16,361

Security (10% of subtotal) 1,636 Contingency (15% of subtotal) 2,454

Detailed design, project management, supervision (2% of subtotal) 327

TOTAL 20,778 Source: TRTA Consultants, 2019

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C. Project Schedule

351. An estimated project schedule is attached in Appendix 9. It is anticipated that the procurement for the work will be completed during second and third quarter of 2019. This will include:

Construction Contractor; Construction Supervision Consultants (CSC).

352. It is anticipated that the selection process will be completed during third quarter of 2019. The construction works should be completed within six to nine months.

D. Implementation Arrangements

353. On 23 December 2018, ADB and the Ministry of Finance agreed that MRRD will undertake the implementation of the required civil works for the realignment of the route bearer highway.

354. MRRD shall coordinate the work with MPW. It is proposed to provide capacity building to both MRRD and MPW on road construction and road maintenance. The existing departmental resources are limited and will need to be developed to properly maintain the road network in project area.

E. Human Resources

355. Approximate number and categories of job opportunities likely to be created as a result of the construction are presented in the table below.

Table 30. Approximate Number of Local Human Resources Required for Implementation Type/Profession For Implementation

(# males) Resident Site Engineers Civil, Geotechnical, with B.Sc. Engineering Degree and 10-15 years’ experience (one each)

2

Assistants Resident Site Engineer Geotechnical, with B.Sc. Engineering Degree and 5 years’ experience

1

Assistants Resident Site Engineer Hydraulics, with B.Sc. Engineering Degree and 5 years’ experience

1

Assistant Engineer Civil, with B.Sc. Engineering Degree and 3 years’ experience or Diploma holder with 8 years’ experience

2

Assistant Engineer Geotechnical, with B.Sc. Engineering Degree and 3 years’ experience or Diploma holder with 8 years’ experience

2

Assistant Engineer Civil / Civil 3D/ AutoCAD, with B.Sc. Engineering Degree and 3 years’ experience or Diploma holder with 8 years’ experience

2

Work Supervisor, Diploma holder with 3 years’ experience

5

Administrator 2 Administration Staff 3 Clerical Staff 2 Skilled Labor 100 Unskilled Labor / helpers 200

Total 322 Source: TRTA Consultants, 2019

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F. Equipment and Machinery

356. The table below presents the likely list of equipment, which would be required during the implementation stage of the subproject. The contractor will provide the equipment and machinery required for execution of this subproject.

Table 31. Equipment and Machinery Required for Implementation Plant Description Quantity Capacity

Long Boom Excavators 3 0.45 - 0.8 m3 Front end loaders / Bulldozer 10 15 ton Dump trucks 15 Grader 3 Steel smooth wheel drum roller 4 Vibratory roller 4 8 - 20 ton Tire roller 4 8 - 20 ton Water Tanks 5 Concrete mixer 5 > 0.6 m3 Asphalt Plant 1 60 ton / hr Crusher plant 1 Processing plant 1 Asphalt finisher 1 2.4 - 6 m Vibrating roller 2 3 - 4 ton and 0.5 - 0.6 ton Vibrating compactor 1 50 - 60 kg Line marker 1 Thermoplastic type Truck crane 2 16 ton and 4.9 ton Rough terrain crane 1 20 ton Dump Truck 1 10 ton Truck 3 2 ton; 3-3.5 ton; 4-4.5 ton


G. Social Considerations

357. Social analysis is being done for the whole project (Component 1, 2, 3 and 4). All civil works will be subject to resettlement safeguards, including compensation for any loss of private land to public use. The approach and interventions of the project are socially inclusive, gender-focused, and community-led. The project will cover poor and vulnerable households, including those headed by women.

358. The consultation and participation plan for the project will maximize participation of stakeholders. A gender equality and social inclusion action plan will ensure that gender and social activities will be implemented and monitored at regular intervals. Data, disaggregated by sex and social and economic background, will be collected annually as part of M&E activity, to establish trends from the baseline social survey undertaken during the TRTA project. This will enable figures to be tracked and social and gender equality results to be measured and reported, as the project progresses. In recognition of the wider social and structural dimensions of gender inequality in the country, the project is expected to yield significant benefits for women.

H. Environmental Considerations

359. Ensuring that environmental considerations are integrated into the planning and development of the project are important to the reconstruction and recovery effort, particularly for infrastructure, including roads.

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360. The proposed project is focusing on realignment, repair, rehabilitation, and reconstruction of damaged and worn-out Route Bearer Highway, and drainage structures that are of critical importance to the local economy. Considering the nature and magnitude of the potential environmental impact, the proposed operations would have to comply with environmental and social safeguard policy requirements.

361. An environmental impact analysis has been carried out as part of the TRTA. The implementing agency should apply the minimum standards during implementation. These are:

Inclusion of standard environmental codes of practice in the realignment, repair and reconstruction;

bid documents review and oversight of construction works by supervision specialists;

Implementation of environmentally and socially sound options for disposal of excess materials and debris, and

Provisions for adequate budget and satisfactory institutional arrangements for monitoring effective implementation.

362. The project requires that the following two aspects be considered in the construction stage:

363. Traffic Accidents: The Engineer and Contractor in charge will both be requested to consider the following so as to assure necessary traffic safety during construction work:

The traffic in the project site must be safely maintained during the execution of the works;

In order to facilitate the traffic, the Contractor shall install and maintain traffic signs, warning signs, guide signs, barricades, rubber cones and other facilities as required by the Engineer in charge, for traffic control;

The Contractor shall submit a traffic control plan to the Engineer for approval; The Contractor shall take necessary care at all times during the execution of the work to ensure traffic convenience and safety; The Contractor shall submit shop drawings showing temporary works for traffic

control to the Engineer for approval; The Contractor shall conduct his operations so as to minimize the obstruction;

inconvenience, and delay to traffic, and shall be responsible for the adequate control of the traffic.

364. Waste Disposal: The design has been performed in general to nearly balance out the cut and fill. This should minimize wastage and disposal issues. The unsuitable material will be disposed in landfills downstream of Main Dahla dam to ensure that the excavated does not interfere with existing streams or water ways. This site was recommended by the Municipality and NEPA for disposal of construction waste.

365. With regard to waste disposal, during construction works, the Engineer will also be requested to consider factors that will assist the Contractor to avoid or minimize any eventual adverse environmental impact.

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VI. RISKS AND MITIGATING MEASURES

366. There are a number of potential risks to the completion of works and successful achievement of the proposed outputs. These risks include for example security concerns at the site, availability of contractors, limited site flooding, availability of construction material, timely and fair compensation to the affected people.

367. In 2016, the Route Bearer Highway realignment construction activities for the originally planned dam raise of 8 m, have been completed successfully.

368. The support from the locals is very high and with appropriate government measures the project shall be managed successfully. A summary of risks and mitigating measures are presented in the table below.

Table 32. Summary of Risks and Mitigating Measures Risks Mitigating measures

Availability of local contractors

Previous 4.3 km raise work for the road was performed by a local contractor in Kandahar. There are number of local civil construction contractors who should be able to manage these works. This was confirmed by MPW, ASBA and MEW.

Security and location of the Explosive ordinance along the proposed route

Security and location of the Explosive ordinance along the proposed route will have to be considered before construction to avoid any loss of life. Contractor has to coordinate with provincial authorities like Afghanistan Mine Action Centre (AMAC) to ensure that the proposed route is safe from underground mines.

Flooding of the site Rains are not a major risk during most months. However, during extreme events, flooding is common in most streams along the route. Contractor has to take this into consideration. The contractor may propose robust measures to economize and speedy construction for approval of the engineer.

Availability of construction material

Recent geotechnical investigations have confirmed availability of significant quantities of construction material (clay core, sand gravel mix, rockfill from the excavation) along the route. Rockfill should also be available from excavation along Route Bearer after Shahjuy village. This material should be investigated to use for sub-base and base material. Drilling and blasting will need careful planning. This is a critical activity and must be managed carefully well in advance to ensure availability of enough material for construction. The contractor must perform investigations to validate the availability of the construction material from various sources and develop strength parameters before start of construction. Cement and gravels can be obtained from various local quarries and are easily available in Kandahar. The proposed pipe culverts should be pre-casted well in advance to use. Asphalt plant and concrete batching plants must be arranged in advance. However, the contractor may propose alternative design depending on local experience at no additional cost to the employer.

Identification and procurement of long lead items

A planning for long lead items will be required. Long lead items have to be identified at the earliest and procurement of these items must be started soon to avoid delay in the construction to avoid unnecessary claims. Asphalt penetration grade should be obtained from Pakistan.

Unnecessary government delays in customs on internationally procured items

MRRD along with MEW and MPW and should identify long lead items and based on experience should plan the schedule to ensure that no delay is caused due to red tape.

Poor planning for the construction

A detailed project plan should be prepared identifying all the critical activities with close coordination with the relevant government departments.

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Weak supervision of works

Improve field security and ensure adequate budget is available in timely manner.

Lack of local security for field staff does not allow freedom of movement

Project risk managers and security team work closely with local police and security senior personnel and community leaders, while the project employs and upskills locally born and resident field staff.

Local leaders subvert project direction in favor of own preferred projects

The broad base of Steering Committee Governance membership and the management group of the PMU with independent monitoring and evaluation functions will ensure development plans and input applications are agreed in advance and stay within project parameters.

Availability of skilled and capable local staff limits progress in key agricultural or added value activities

The project will recruit local staff and expect to upskill these in the first six months of employment in a train the trainer approach. International specialists will only be used to support local staff and the project will foster a bottom up introduction through stimulating demand for produce rather than a top down imposition of ideas, once key areas have begun to develop.

Local governance fails to understand and support integrated project methodology

Close relationships will be developed early in the program with local governance bodies like ASBA, MPW and MRRD, including the Provincial Governor’s office, enjoying positions within the Steering Committee, along with bottom up initiatives being supported by rural and peri-urban communities, political figures, ANA/ANP leadership, etc.

Currency value depreciation and fluctuations make forward budget planning very difficult

The currency of transactions internally will be Afghanis and external purchases will be made in USD or Euros with hard currency for capital items drawn down from external sources as and when required. Currency depreciation will favor exports which are within scope of the project and which will earn foreign currency to recycle for input purchases under commercial mechanisms.


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REFERENCES

ADB (2016), Asian Development Bank, Project Administration Manual, 50062-001, Road Asset Management Project, Afghanistan.

AASHTO (1993), American Association of State Highway and Transportation Officials (AASHTO). 1993. AASHTO Guide for Design of Pavement Structures. Washington, D.C.

Gupta, Ram S., Hydrology and Hydraulic Systems, Second Edition. Waveland Press, 2001.

JICA (2005), Basic Design Study on the Project for Rehabilitation of Roads in Mazar-e-Sharif in Afghanistan.

MPW, Ministry of Public Works, Afghanistan (2005), Road Maintenance Manual for Afghan Govt

Engineers.

MRRD (2013), Ministry of Rural Rehabilitation and Development, Afghanistan, Rural Roads

Manual.

Morrison-Knudsen Afghanistan, Inc. 1956. Final Design Report on Kajakai Dam, Arghandab Dam

and Boghra Canal Projects. International Engineering Company.

NHA (2014), National Highway Authority Pakistan, Composite Schedule Rates for Quetta, Baluchistan, Pakistan

NHA (2014), National Highway Authority Pakistan, General Specifications 1998, Pakistan

TRTA Consultants. 2018. Hydrology Study Report.

TRTA Consultants. 2019. Component 1: Feasibility Design Report.

TRTA 2019. Geotechnical Report – (Draft)

UN Population Fund. 2005. A Social-Economic and Demographic Profile of Kandahar Province, Afghanistan.

USACE. 2011, Designing Roads and Retaining Structures for Nangarhar Province, Afghanistan,

ERDC/CRREL TR11-01

USACE. 2011. 3.7 Dahla Dam FS Appendix A Hydrology.

USACE. 2011. Arghandab Irrigation Rehabilitation Dahla Dam.

USACE. 2013. Dahla Dam Water Improvement Project – Focused Feasibility Study Report.

USACE. 2014. Geotechnical Report – Louis Berger Report.

UFC, UFC 3-230-17FA, Drainage in Areas Other Than Airfields, 16 Jan. 2004.

USACE, EM 1110-2-1415, Hydrologic Frequency Analysis, 5 Mar 1993.

USACE, EM 1110-2-1417, Engineering and Design - Flood-Runoff Analysis, 31 Aug 1994.

USACE, EM 1110-2-1420, Hydrologic Engineering Requirements for Reservoirs, 31 Oct 1997.

USACE. 2015. Route Bearer Highway Realignment Hydrology brief.

Williams-Sether, Tara. 2008. Streamflow characteristics of streams in the Helmand Basin, Afghanistan, Fact Sheet 2008-3059. U.S. Agency for International Development.

Xavier,A. Cronin, (2003), The Asphalt Ribbon of Afghanistan, Rebuilding the Kabul to Kandahar Highway

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APPENDIXES (ATTACHMENTS)

APPENDIX 8: ROAD REALIGNMENT COST ESTIMATES

APPENDIX 9: ROAD REALIGNMENT PROJECT SCHEDULE

APPENDIX 10: ROAD REALIGNMENT PROJECT SPECIFICATIONS

APPENDIX 11: ROAD REALIGNMENT DRAWINGS

RB-10-01 to 37: GENERAL ✓ Cover sheet; ✓ List of drawings; ✓ General notes; ✓ Project location; ✓ Geology; ✓ Existing highway photos; ✓ Highway design details (super elevation, road markings and signs); ✓ Culverts design details; ✓ Causeways design details; ✓ Schedule of culverts; ✓ Setting out data; ✓ Hydrology; ✓ Borrow area / investigations details; and ✓ Spoil / Construction waste dump site details.

RB-20-01 to 03: Typical Cross Sections ✓ Pavement design and cross section details;

RB-30-01 to 37: Plan and Profile ✓ Plan and Profile details from Station 0+000 to 9+300 m;