Preventive Maintenance Manual - Southeast Asia -

2009 The Japanese Institute of Irrigation and Drainage

Preface The Manual of Preventive Maintenance Measure (South East Asia Chapter) is summarized as a useful reference when “Stock Management”, which is a method to aim at prolongation of existing irrigation and drainage facilities by deliberately repairing or reinforcing the facilities, is applied.

Stock Management of irrigation and drainage facilities means a series of activity of recovering degraded functions, minimizing the causes of function degradation, or repairing or reinforcing the facilities if needed in order to fulfill its functions as long as possible. The method of minimizing the construction cost of target irrigation and drainage facility, cost of repairing in durable period, and decommissioning cost in total has to be employed to achieve appropriate Stock Management. In this instance, this total cost is called Life Cycle Cost. It is necessary to obtain minimum Life Cycle Cost by selecting appropriate repairing method at well-timed opportunity among the several repairing methods and timings which can extend the durable period. The purposes of this manual are to explain the concept of Stock Management of irrigation and drainage facilities, the facility inspection method, outline of countermeasure construction for repairing and reinforcing, and methodology of Life Cycle Cost calculation etc. as easy as possible. The basic parts of this manual refer “The Guidelines of Function Preservation of Irrigation and Drainage Facilities” which has published by Japan Association of Agricultural Engineering Enterprises (JAGREE) in 2007. In addition, the results of field survey about preventive maintenance measure are reflected to this manual. The field survey has been implemented from year of 2006 to 2008 in Way Jepara area, Lampung Timur, Indonesia and Tha Ngon area, suburb of Vientiane, Lao PDR where extended period has passed, and the social and economical conditions, and land use have been dramatically changed since the completion of the irrigation and drainage facility construction.

Of course, Stock Management is still a new concept, various studies and researches, therefore, would be carried out in many countries including Japan. Consequently the concept and methodology of Stock Management are expected to be evolved. From that standpoint, the contents of this manual are written on the basis of present knowledge. This manual is published as the result of the study commissioned by the International Affairs Department, Minister’s Secretariat, Ministry of Agriculture, Forestry and Fisheries (MAFF). We deeply acknowledge the MAFF staff concerned who led us in various phases. The committee of the Study Project on Efficient Economic Cooperation of Agriculture and Forestry which is composed of academic experts has been established to obtain the guidance and advice for the study, including investigation of this manual. Furthermore, we are indebted to the administration official in the government of Indonesia and the government of Lao PDR, and JICA experts in Lao PDR for their assistance of the field surveys. We would like to offer our heartfelt gratitude.

March 2009 Japanese Institute of Irrigation and Drainage (JIID) President Masashi Morita

Contents Chapter 1 Objectives.............................................................................................................. 1 Chapter 2 Outline of Preventive Maintenance Measures ...................................................... 3

2.1 Basic ideas.................................................................................................................... 3 2.2 Performance ............................................................................................................... 5 2.3 Functions and performance ........................................................................................ 6

Chapter 3 Daily Examination................................................................................................. 7

3.1 Current situations of water management in Southeast Asia......................................... 7 3.2 Facility inspection ........................................................................................................ 7 3.3 Survey method............................................................................................................ 11 3.4 Methods of determination .......................................................................................... 12

Chapter 4. Function Evaluation ............................................................................................ 16

4.1 Objectives and procedures ......................................................................................... 16 4.2 Methods of determination .......................................................................................... 18 4.3 Frequency of surveys ................................................................................................. 20 4.4 Evaluation of soundness............................................................................................. 20 4.5 Evaluation................................................................................................................... 22 4.6 Grouping of results..................................................................................................... 24

Chapter 5 Prospecting for Deterioration .............................................................................. 26 Chapter 6 Repair Works ....................................................................................................... 30

6.1 Outline of repair works .............................................................................................. 30 6.2 Selecting repair work methods................................................................................... 31

Chapter 7 Calculation of Life Cycle Costs .......................................................................... 32

7.1 Stock management and life cycle costs...................................................................... 32 7.2 Methods to calculate life cycle costs.......................................................................... 33

Chapter 8 Examples of Repair Work Scenario .................................................................... 37

Reference material The deterioration situation photograph of course structure ..................................................... 43 Glossary.................................................................................................................................... 49

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Chapter 1 Objectives This manual is for irrigation drainage engineers mainly in Southeast Asia, with the aim of prolonging the service life of irrigation and drainage facilities by maintaining and managing them appropriately, or for formulating preventive maintenance measures. This manual is applied to concrete canals including lined canals among open canals for irrigation and drainage.

The irrigation and drainage work conducted in Southeast Asia has been focused mainly on the development of water resources and main irrigation and drainage facilities, due to restrictions in funds. In other words, tertiary canals that directly supply water to farmlands are not built by the large-scale irrigation development project in many cases. Construction of tertiary canals is often left to local governments and farmers’ associations. In view of the restriction on funds and environmental conservation, it seems inevitable that projects for building new irrigation and drainage facilities for expanding the irrigated land areas would remain limited. Under the circumstances, it has become important to attempt to extend the service life and effective usage of the existing irrigation and drainage facilities, many of which have been used for over 30 years since going into operation. For this purpose, it is necessary to formulate appropriate management and preventive maintenance measures for irrigation and drainage facilities, by adopting the concept of stock management. In addition, the establishment of operation and maintenance system and the capacity building for the engineers are also necessary to carry out preventive maintenance measure. Maintenance measures are categorized into preventive and post-maintenance measures. (1) Preventive maintenance measures

Measures that are implemented with the purpose of extending economically the service life of a certain facility in order to minimize the life-cycle cost before the performance required of the facility declines to levels below the control level, thus not allowing any further decline in performance.

(2) Post-maintenance measures

Measures implemented after the performance required of a certain facility has declined to a level below the control level due to deterioration and other causes.

The scope of application of this manual includes irrigation and drainage facilities, but not earth canals. The function evaluation procedures concern concrete canals (including lined canals). The flow of function evaluation procedures for concrete structures, such as dams and pump situation are the same.

2

Planning/ design

Construction

Facility maintenance

Repair works

Repair works

Facility maintenance

Prolongation of facility service life / cost reduction

* By implementing preventive maintenance measures, it becomes possible to use the facility longer than the service life assumed at the time of design, thereby reducing the life-cycle cost.

Figure 1: Concept of Preventive Maintenance Measures

Initial inspection

Plan

Action

Check

Do

This “Plan -> Do ->Check -> Action” should be perpetually carried out.

3

Chapter 2 Outline of Preventive Maintenance Measures 2.1 Basic ideas The method for determining the preventive maintenance measures for preserving the functions of irrigation and drainage facilities is as follows. (1) Based on continuous function evaluation and assessment, several combination of

repair work measure and life-cycle cost are studied. (2) Based on the comparison, appropriate preventive maintenance measures are

formulated and repair and reinforcement work is provided. Stock management refers to the technical system and management method for extending of facility’s service life and for reducing the life-cycle cost, through preventive maintenance measures implemented based on facility function evaluation. The life-cycle cost of irrigation and drainage facilities refers to the total of cost of their planning, design, construction, maintenance, management and scrapping. The purpose of stock management is to reduce the life-cycle cost and prolong the service life of facilities. Irrigation and drainage facilities deteriorate after construction with the passage of time, to a point below the marginal working limit. Or, excessive maintenance costs arise with continuing usage. In either case, it is necessary to replace the facilities. Looking at each component that constitutes the facilities, however, their levels of deterioration are not the same. Even among facilities with the same structure, there is a mixture of portions that have deteriorated to the point where rebuilding is inevitable, portions that can be repaired or reinforced for usage, and portions that would not affect performance and only observation would be necessary for the time being. As such, it is efficient to provide precise measures that suit the conditions of each component of the facility. Irrigation and drainage facilities have conventionally been replaced when they reached a condition that makes rebuilding inevitable, or when the farming environment has changed and the facility no longer satisfies the necessary functions. From now on, it is necessary to evaluate the soundness and factors behind deterioration based on continuous function evaluation of the facilities, and implement measures that are possible. It is also necessary to compare the costs for preserving the performance of the facilities when implementing the project. Furthermore, the unit for comparison should not be broad categories such as by project areas or canal lines. Instead, it is necessary to group facilities according to their level of deterioration. Through systematic function evaluation, the conditions regarding facility performance and deterioration would be clarified. This would enable a clarification of the risks of facility collapse and more economical measures that can be chosen. Through these efforts, appropriate measures could be provided to allow the functions of irrigation and drainage facilities to be carried out fully.

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Daily examination

Function evaluation

Assessment

Studies on repair works

Life-cycle cost

Planning

Implementing preventive maintenance measures

A rational plan is prepared after comparing the life-cycle costs, taking into account the time

of implementation and order of priority of repair works.

Project history and repair

history are summarized, and facility managers are interviewed for the survey.

Outline of the entire

channels is surveyed by visual inspection.

Portions that require focused surveys are identified.

Data are collected for judging

the degree of deterioration at focused measurement locations.

Visual survey from close proximity is mainly conducted.

Preliminary survey (First) Field survey (Second) Field survey

Deterioration factors are

estimated based on the result of function evaluation.

Progress in deterioration of the facilities is ranked for

each survey unit Grouping is done according to deterioration factors and

facilities concerned.

Estimation of deterioration factors Determination on soundness and facility grouping

Prospect for the progress

in deterioration is clarified for each group.

Several repair work

methods are selected for each group of facilities.

Several repair work scenarios

are prepared by combining several repair work methods and the time of their implementation.

Prospect for progress in deterioration

Selecting repair work methods Repair work scenarios

Function preservation costs are calculated for each repair work scenario and each facility.

Life-cycle cost

Figure 2.1: Scheme for Preventive Maintenance Measures

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2.2 Performance Stock management applied to irrigation and drainage facilities focuses on the functions of these facilities and tries to maintain the performance within a certain range by adopting optimum methods. In this case, it is necessary to clearly indicate the allowable limit of decline of performance.

Stock management is a method that selects the most economical means in relation to the time and methods of repair work, among possible means for maintaining specific functions within a level between that at the time of construction and that which does not allow further decline in performance. The control level refers to a range of allowable decline of performance, and needs to be determined taking into consideration the importance of each facility in terms of agriculture, as well as the environmental and disaster risks.

Construction

Perf

orm

ance

leve

l

Function evaluation

Level of repair work (targeted performance)

Range of performance management

Lowest limit of control level

Working marginal limit level

Years elapsed

Repair works

Figure 2.2: Performance Degradation Curve and Control Level

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2.3 Functions and performance Functions of irrigation and drainage facilities refer to the roles intrinsically performed by these facilities, and include water use functions, hydraulic functions and structural functions. The capacity to perform these roles is called performance, which can be represented specifically in terms of water flow, water diversion and other water uses and scientific and physical safety. It should be noted that these functions are in a multilayered relation.

The functions and performance of irrigation and drainage facilities are shown below.

Water use functions: Flexibility in water distribution, maintenance and management, environmental conservation

Hydraulic functions: Water conveyance , water diversion control

Structural functions: Mechanical safety, durability

Maintenance costs, number of accidents Total planted area

Water flow volume, roughness coefficient, cross-sectional area of flow

Strength, attrition, deterioration, durable period

Indexes representing performance

Figure 2.3: Functions and Performance of Irrigation and Drainage Facilities

Functions of irrigation and drainage facilities

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Chapter 3 Daily Examination 3.1 Current situations of water management in Southeast Asia When irrigation project is performed in Southeast Asia, experience shows that securing farmers’ participation is an important factor. In general, the conventional water management by public institutions is said to be inefficient in many ways. By transferring a part of water management responsibilities, water management becomes more efficient.

Irrigation management transfer (IMT) is the concept of transferring a part of the facility management to farmers or a farmers’ association. Even though IMT represents a simple act of transferring irrigation facility management, in the background is the idea that the public should manage the main canals while farmers should manage the tertiary canals. Sufficient education and training on operation and maintenance are necessary when transferring water management rights to farmers. In Southeast Asia, this is not yet sufficient. Also, farmers cannot provide repair and reinforcement work by themselves even when irrigation and drainage facilities are damaged by a disaster, due to cost and other factors. Therefore, water management systems and public assistance systems that are suitable for the conditions in each country need to be developed in order to realize appropriate water management. 3.2 Facility inspection In order to maintain irrigation and drainage facilities in good conditions, it is indispensable to carry out appropriate evaluation and provide the necessary measures. In order to carry out an appropriate evaluation, it is necessary to obtain information related to the facility safety, usage situation and effects on third parties in addition to the information gained through daily inspections.

Inspections can be divided into the initial inspection, routine inspection, and emergent inspection, according to their purpose, frequency and processes. By conducting these inspections and comparing the data, the information necessary for rational maintenance can be obtained, including the changes in the conditions of irrigation and drainage facilities since the start of usage and prospects of the conditional changes of the facility after the inspection. The categories of inspection are shown in the diagram below.

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(1) Initial inspection

Initial inspections are performed for obtaining the initial information on irrigation and drainage facilities. The information obtained is used as the default values of the facilities. Since the results of initial inspections provide the basic data for formulating maintenance plans, the survey items and methods should be selected so that appropriate information can be obtained. Also, the obtained information needs to be managed appropriately. The survey items for the initial inspection of a concrete structure are shown below as an example.

1) Information obtained from design drawings

Applied standards Design durable period Design values of concrete performance Design values of covering, reinforcement arrangement, etc. Form, dimensions and others

2) Information obtained from records of inspection performed after construction

Items related to construction work (builders, construction date, type of structure) Items related to concrete quality (materials used, records of composition, records

of unit water volume, average and minimum values of controlled strength) Items related to reinforcement (records of covering and arrangement, fixed

positions, joint positions) Items related to initial defects (records of cracks and other damage and repair

works provided)

Conducted before handing over the facility its administrator

Conducted after the facility was handed over to its administrator

Initial inspection

Routine inspection

Extra inspection

Emergency inspection

Conducted for making an inventory of the facility and for clarifying the initial conditions

Conducted daily for clarifying the changes in conditions of irrigation and drainage facilities

Conducted from once a year to once every few years to clarify the conditions of irrigation and drainage facilities in abroad range.

Conducted for irrigation and drainage facilities damaged by external and other forces

Conducted for irrigation and drainage facilities similar to those damaged * Conducted when similar accidents have

occurred in similar irrigation and drainage facilities

Figure 3.1: Categories of Inspection

Daily inspection

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Appearance of the structure at the time of the start of maintenance (exterior form, dimensions, colors, whether there is any deformation)

(2) Daily inspection

Daily inspections are simple visual inspection and other types of inspections performed daily by the facility administrator, within the scope that can be confirmed during a patrol, etc. The facilities need to be maintained in a good condition; the operation records, and the history of accidents, inspections and improvement work need to be organized and stored appropriately.

(3) Routine inspection

Routine inspections are performed periodically from once every year to once every few years, in order to clarify the changes in conditions of irrigation and drainage facilities. The structure is surveyed in a broad range by visual inspection and utilizing measuring instruments. The reliability and safety of facilities can be ensured and their service lives can be prolonged, if patrolling and visual inspection of the structures and surrounding conditions and on the facility operation are performed appropriately, along with minor improvement work within the scope of daily operation. For this reason, facility administrators need to carry out daily maintenance appropriately, so that the facility can be maintained in good conditions. If facility administrators find any abnormality in the routine inspection, they should report it immediately to higher-ranking organizations. The higher-ranking organizations perform function evaluation, and study repair works based on the results.

(4) Extra inspection

Extra inspections are performed when irrigation and drainage facilities are damaged by an earthquake, hurricane, or collision with a vehicle or heavy equipment. In these cases, an extra inspection needs to be performed promptly.

(5) Emergency inspection

When an accident occurs or severe deformation is found, even if no accident has occurred, in a certain irrigation and drainage facility, emergency inspection are performed in similar irrigation and drainage facilities, even if no accident has occurred, in order to confirm whether there is a possibility of occurrence of similar accidents or deformation. The inspections are performed utilizing appropriate methods to determine the causes of the accident and to confirm the presence of a similar deformation.

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Table 3.1: Survey Items Item Information Method

Outline of structure

Specifications, design standards Design drawings Construction work records Inspection records Maintenance records

Document checking Interviews

Initi

al in

spec

tion

Usage conditions of structure

Usage conditions Conditions of surrounding

environment

Visual inspection Interviews

Abnormalities and changes in appearance

Presence of cracks Discoloration of concrete Breakdown, separation Whether there is exposure,

corrosion, or breakage of steel reinforcement

Whether there is a deformation Whether there is rust Whether there is water leakage Whether there is free lime Whether there is gel

Visual inspection Beating by test hammer Method based on reactive

force

Conditions of concrete

Information on materials used and composition

Whether there is bleeding or internal void

Water content of concrete Physical properties (strength, void

structure, etc.) Chemical properties (hydrates,

active substances, etc.)

Concrete test hammer Core sampling,

breakdown, drill debris sampling, etc.

Conditions of steel reinforcement

Amount of reinforcement Reinforcement positions, diameters,

covering Conditions of fastenings and joints Conditions of joining sections

between column and beam

Method by chipping Checking design

drawings Direct measurement

Dai

ly a

nd ro

utin

e in

spec

tions

Conditions of ancillary facilities

Conditions of ancillary facilities Direct measurement Checking design

drawings

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3.3 Survey method Needless to say, the survey method differs according to the type of inspection. Initial inspections are mainly performed by checking documents and visual inspection. The routine inspections are performed mainly by visual inspection and using inspection devices. The emergency inspections are required to combine various methods suitable under the circumstances.

(1) Document checking

Information related to the structure can be obtained by surveying documents such as the specifications applied to the structure, design standards, design drawings, construction work records, investigation record, inspection records, repair work history, etc. Information can also be obtained by interviewing the facility administrator.

(2) Visual inspection

When concrete deterioration progresses, deformation often appear on the concrete surface. In inspections, therefore, visual inspection of concrete surfaces is a fundamental method. The items to be visually observed and their descriptions are described below. A. Discoloration, stains: Area of discoloration and stains, whether white gel, free

lime and others have been generated, whether water leakage has occurred and the scope

B. Cracks: Direction of most conspicuous cracks, pattern, number, width, length and whether rusty liquid has seeped out

C. Breakdown, separation: Number of locations and areas of breakdown and separation

D. Exposure, corrosion, or breakage of reinforcement: Covering, number and length of exposed portions, degree of corrosion

E. Displacement and deformation of the structure: Degree of deflection, displacement and subsidence

(3) Methods using inspection devices

Information obtained by visual observation is only limited to that related to deformation on the surface and near the surface layer of concrete structures. Therefore, methods that use inspection devices are implemented when the conditions inside of concrete need to be clarified, or when more detailed information is needed for estimating the deterioration mechanism or judging the degree of deterioration. By beating the concrete surface with a hammer, the existence of voids near the concrete surface layer can be clarified to some degree. At the same time, deterioration inside the concrete can be estimated by discerning the level of impact and the sound quality. Destructive inspection mainly include core sampling, chipping, and steel reinforcement sampling. These are used to obtain information related to the physical properties and condition of deterioration of concrete and steel reinforcement. However, these methods could hinder the functions of the structure. Care must be exercised during the survey, so

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as not to degrade the functions of the structure. 3.4 Methods of determination The determination criteria need to be established if appropriate daily inspection is to be implemented. The determination criteria comprise the condition of facility functions, past accidents, history of repair works, conditions of the surrounding environment and others.

The following three categories of determination criteria should be established, according to the facility conditions: A. no repair work needs to be provided; B: function evaluation for determining whether repair or reinforcement measures are necessary; and C: prompt function evaluation is necessary. The determination criteria for a concrete canal are shown below as an example. Table 3.2: Example of Determination Criteria for Daily Inspection of Concrete Canal

Category Description A There is no deformation or function degradation; or, if any, they are only

minor ones, and emergency measures or a function evaluation is not necessary.B Even though there is deformation and function degradation, no emergency

measure is needed. However, function evaluation needs to be performed todetermine whether repair and/or reinforcement measures are necessary.

C Significant deformation and function degradation is observed, and the irrigation and drainage facilities are judged to be unable to fully perform their functions. Therefore, a function evaluation needs to be performed to determinewhether fundamental measures are needed, after providing emergency measures.

The locations determined to fall under Category C need to be kept under surveillance by implementing priority daily inspections, until function evaluation and emergency measures are provided.

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Table 3.3: Example of Daily Inspection Table Surveyed point: Date: Measurement by:

Determination category Item A B C

Primary determi- nation

Secondary determi-nation

(1) Slanting, deformation, subsidence, damage, etc.

No slanting, deformation, subsidence or damage is observed.

Slanting, deformation, subsidence or damage is observed but the water conveyance capacity is maintained.

Slanting, deformation, subsidence or damage is observed, and the condition could spread over the entire structure.

(2) Cracks Minute cracks are observed but do not affect the functions.

Cracks are observed overall.

Cracking has progressed and could spread over the entire facility.

(3) Breakdown, separation

No breakdown or separation is observed.

Bleeding that could lead to breakdown or separation is observed.

Numerous breakdown and separation are observed.

(4) Exposure of reinforcement

No reinforcement is exposed.

The concrete member has become thin, as well as the covering on reinforce- ment.

Reinforce- ment is exposed.

(5) Breaks on joints, steps

No break on joint or step is observed.

Displacement of joint or step is observed, but not water leakage.

Water stop or joint material is damaged or has fallen off due to displacement of joint or a step, and water leakage is observed.

(6) Water conveyance

No dysfunction of water conveyance is observed.

Deformation or subsidence of a canal is observed, but the water conveyance is maintained.

The flow’s cross-section area has become insufficient due to deformation or subsidence of the canal and dysfunction of water conveyance is observed.

1. C

ondi

tions

of f

acili

ty fu

nctio

ns (c

oncr

ete

cana

l)

(7) Attrition No sign of attrition is observed.

Partial attrition is observed.

Attrition has progressed, causing coarse aggregate to be exposed.

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Determination category Item A B C

Primary determi- nation

Secondary determi-nation

(1) Dysfunction of water division and distribution capacities

Water division and distribution functions have not degraded.

The structure is deformed at locations of water division work, causing water division and distribution functions to degrade.

The structure is deformed at locations of water division work, causing water division and distribution functions to degrade significantly from the specified level.

(2) Distortion in mechanical and electrical facilities

No deformation or function degradation is observed.

Gate and other structures have deformed or distorted, but operation is not hindered.

Gate and other structures have deformed or distorted significantly, and normal operation is not possible.

2. C

ondi

tions

of f

acili

ty fu

nctio

ns (s

truct

ure)

(3) Rust in mechanical and electrical facilities

Rusting has not progressed.

Rusting has progressed but the strength is not declining for the time being.

Rusting has progressed significantly and the strength could decline.

3. H

isto

ry o

f rep

air a

nd

rein

forc

emen

t

There are records of accident and repair/reinforcement work but these are minor ones.

There are records of accident and repair/reinforcement work but the damage has remained partial.

There are records of accident and repair/reinforcement work and damage has spread overall.

4. S

urro

undi

ng

cond

ition

s

Impacts on third party are believed to be minor even if an accident occurred.

The facility is close to houses and public facilities but they are not likely to suffer damage even if an accident occurred.

A part of the facility is close to houses and public facilities and they could suffer significant damage if an accident occurred.

5. M

aint

enan

ce

Facility management and recovery from accident is easy.

The facility functions are degraded and facility management and recovery from accident is difficult.

Function deterioration of the facility has progressed and arrangements are in appropriate, making facility management and recovery from accident extremely difficult.

Opinions of administrator (Fill in comments as necessary about what is needed for function evaluation and emergency measures)

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The criteria for secondary determination shall be as follows. Item Primary determination Secondary determination

Three or more items are categorized as C

Rated as C

Three or less items are categorized as C and four or more as B

Rated as B

1. Conditions of facility functions (concrete canal)

Other than the above Rated as A One or more item is categorized as C

Rated as C

Two or more items are categorized as B

Rated as B

2. Conditions of facility functions (structure)

Other than the above Rated as A If one or more item was rated as C in the secondary determination, the facility administrator shall report to the higher-ranking organization and study whether function evaluation needs to be performed.

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Chapter 4. Function Evaluation 4.1 Objectives and procedures The objectives of function evaluation are to clarify the degree of deterioration of irrigation and drainage facilities as quantitatively as possible and to identify the deterioration factors. In view of efficiency, function evaluation is performed in the following procedures. (1) Preliminary survey by collecting document and interviewing facility administrators (2) (First) Field survey by visual observation (3) (Second) Field survey for quantitative survey through visual observation from close

proximity, measurements and tests Additional detailed surveys are performed as necessary.

(1) Preliminary survey

In preliminary surveys, design drawings, management records possessed by the facility administrators and other materials are collected, at the same time the interviews are conducted. Information needs to be gathered efficiently by surveying documents including design drawings and records of management, accidents, repair works and others, and by interviewing the facility administrators.

(2) (First) Field Survey

The (first) field survey aims at a broad clarification of the conditions and factors of facility deterioration performed through visual inspection by an engineer with a technical background. It is also advisable to define the survey units, the quantitative survey items and other specific matters concerning the (second) field survey. The facility administrator, who is thoroughly informed of the normal conditions through daily examinations, should accompany the (first) field survey. The results of the survey shall be compiled using the field survey table.

(3) (Second) field survey

For the (second) field survey, the survey items and units are to be set based on the information obtained in the preliminary and (first) field surveys and taking into consideration the type and degree of importance of facilities. The second field survey is performed by visual inspection from close proximity and quantitative measurements. Quantitative survey for the indices necessary for prospecting facility deterioration and studying repair works should also be performed. Additional detailed surveys are performed by experts and testing organizations as necessary, when determination is not possible only with the field survey results.

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Collecting documents on the irrigation and drainage facilities

Survey by interview

Organizing survey results

Status of function degradation is clarified and factors of facility deterioration are estimated for listing items of importance and cautions of field surveys.

Visual inspection

Outline of facility deterioration is clarified, deterioration factors are identified, survey units and locations are set and local deterioration is clarified

Function evaluation Evaluation by visual inspection from close proximity and utilizing inspection devices

Organizing evaluation results

Construction outline Collecting design and construction

materials Collecting daily inspection records Collecting history of accidents and

repair work Clarifying management issues

Visual inspection

Visual inspection from close proximity, examination by touch, hammering test

Measurements by means of simple measuring devices

(Detailed survey) Destructive and non-destructive tests and performance survey through hydraulic analysis and structural analysis are performed as necessary.

Preliminary survey

(First) Field survey

(Second) Field survey

Figure 4.1: Procedural Flow of Function Evaluation

Studying countermeasures

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4.2 Methods of determination The determination criteria need to be established for evaluating functions appropriately.

The determination criteria can be categorized from a to d, in accordance with the progress in deterioration. The determination categories a to d are converted to points in function evaluation. Examples of determination criteria for concrete open canal are shown below.

Table 4.1: Example of Determination Criteria for Concrete Open Canal Determination category Item a b c d

(1) Destruction, damage, or erosion of embankment, or sediment of soil in canal

No destruction isobserved.

Small-scale destruction is observed but it is not a problem.

Large-scale destruction is observed and canal functions have degraded.

Large-scale destruction is observed and canal functions have degraded significantly.

(2) Cracks No crack is observed.

A few cracks are observed.

Cracks are observed overall.

Cracking has progressed and could spread over the entirestructure.

(3) Breakdown and separation of concrete

No breakdown or separation is observed.

The dimension of the breakdown or separation is between 10 cm and 50 cm.

The dimension of the breakdown or separation is between 50 cm and 1 m.

The dimension of the breakdown or separation is greater than 1 m.

(4) Abrasion of concrete No sign of attrition is observed.

Signs of attrition are observed partially.

Signs of attrition are observed and the environment is prone to attrition. (Sections with rapid flow or overflow)

Attrition has progressed and coarse aggregates are exposed.

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Determination category Item a b c d (5) Interruption in joint,

step No interruption in joints or step is observed.

Displacement and opening of joints are observed but not water leakage.

Water stop and joint materials are damaged and have fallen off due to displacement and opening of joints, and water leakage is observed.

(6) Dysfunction of flow conveyance

No dysfunction of flow is observed.

Deformation and subsidence of canal are observed, but not dysfunction of flow conveyance

Deformation and subsidence of canal are observed, along with dysfunction of flow conveyance .

(7) Dysfunction of water division and distribution capacities

No deformation is observed with the structure.

The structure has deformed but no dysfunction of water division and distribution capacities is observed.

Deformation of the structure led to dysfunction of water division and distribution capacities.

(8) Distortion in mechanical and electrical facilities

No function degradation caused by distortion is observed.

Distortion is observed but operation is not hindered.

Distortion is significant and normal operation is not possible.

(9) Rust in mechanical and electrical facilities

No rust is observed.

Rust is observed at few locations but there is no problem.

Rusting has progressed but strength is unlikely to decline for the time being.

Rusting has progressed significantly and the strength could decline.

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4.3 Frequency of surveys The frequency of function evaluation needs to be set from a wide range of standpoints, taking into consideration the extent of the effect of a significant decline in performance along with deterioration of the facilities. Function evaluation needs to be performed periodically for facilities that have not yet deteriorated so much, in order to estimate future deterioration.

Function evaluation is performed in order to discern how a significant degradation in performance of the deteriorated facilities and accidents would affect the agriculture and surrounding environment, up to what levels these effects can be allowed, and the degree of difficulty and time required for recovery. The frequency of function evaluations needs to be set appropriately, also taking into consideration the cost of the surveys.. Even when the risk associated with the accidents caused by deterioration is small, a function evaluation needs to be performed periodically in order to observe and estimate what deterioration processes the facilities would follow. 4.4 Evaluation of soundness In order to prospect the progress in deterioration and study repair works, evaluation of facility’s soundness is performed. On the occasion of evaluating the soundness of the facilities, the degree of deformation should be comprehensively clarified based on the facility conditions revealed by the function evaluation.

Soundness needs to be evaluated based on diverse performance indices required of the facilities. However, water use functions, hydraulic functions and structural functions degrade in many cases due to decline in the performance of structures, so the soundness of reinforced concrete structures is evaluated based on the cracks and other indices that relate to the external form of the facilities. When water usage and hydraulic performance are degraded significantly and they themselves require attention, or when there are factors other than the degradation of structural performance that largely affect the performance, they need to be taken into account also. Evaluation of facility’s soundness should be performed for each of the internal factors such as degradation of members, the external factors such as distortions caused by external forces, and other factors such as displacement of members.

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Table 4.2: Example of Evaluation for Concrete Structure’s Soundness Soundness

index Definition Examples Required repair

works S-5 Almost no deformation is

observed. (1) Conditions are almost the same as those at the

time of facility completion. (The deterioration process is in the incubation stage)

No repair work is necessary

S-4 Minor deformation is observed.

(1) Minor cracks and attrition have developed in the concrete.

(2) Minor deformation is observed with joints and around the structure, but normal usage is not hindered. (The deterioration process is in the development stage)

Observation is needed

S-3 Deformation that is not minor is observed. Repair works to retard the progress in deterioration is needed.

(1) Cracks that reach the reinforcement have developed, or concrete has separated due to corrosion in the reinforcement.

(2) The aggregate has fallen off due to attrition. (3) Significant water leakage has occurred due to

deterioration in joints. (The deterioration process is shifting from the development to acceleration stage)

Repair works

S-2 Deformation that affects the structural stability of the facilities is observed. Reinforcement work is also necessary.

(1) Concrete and reinforcement are broken down partially.

(2) The concrete structure is obviously deformed due to ground deformation and increase in the earth pressure on back surface. (The deterioration process is in the acceleration stage)

Reinforcement work

S-1 Deformation that gravely affects the structural stability of facilities is observed. The facilities need to be rebuilt.

(1) Passing-through cracks have developed. The state of S-2 has progressed further.

(2) Rebuilding would be more economical than providing reinforcement work. (The deterioration process is in the deteriorated stage)

Rebuilding

The categories of soundness indices are shown below.

Incubation stage

Development stageAcceleration

stage Deteriorated

stage

Start of reinforcement corrosion

Corrosion and cracks are generated in concrete

Time Det

erio

ratio

n ca

used

by

neu

traliz

atio

n D

egra

datio

n in

m

embe

r per

form

ance

Figure 4.2: Concrete Deterioration Process

22

4.5 Evaluation The results of function evaluations are converted to points in order to indicate the progress in deterioration quantitatively, and grouped according to the degree of soundness.

Scores are set beforehand for each of the types of deformation scored as a, b, c, or d in the determination category table, and the results are converted to points to suit the degree of deterioration. Table 4.4: Example of Determination Categories for Concrete Open Canal

Score for determination category Item a b c d (1) Destruction, damage or erosion of

embankment or sedimentation of soil in the canal

0 1 2 3

(2) Cracks 0 1 2 3 (3) Breakdown and separation of concrete 0 1 2 3 (4) Attrition of concrete 0 1 2 3 (5) Interruption in joints, steps 0 2 3 (6) Dysfunction of flow conveyance 0 2 3 (7) Dysfunction of water division and

distribution capacities 0 2 3

(8) Distortion in mechanical and electrical facilities 0 2 3

(9) Rust in mechanical and electrical facilities 0 1 2 3

23

Example Function Evaluation Table (Open Canal) Measurement location: Canal Date: , Measured by: Sections [1,100 m to 1,200 m]

Section 1100 to 1110 1110 to 1120 1120 to 1130 1130 to 1140 1140 to 1150 1150 to 1160 1160 to 1170 1170 to 1180 1180 to 1190 1190 to 1200 Grand total

Score

(2)b 1 (4)c 2 (5)c 2

(3)c 2 (4)c 2 (2)b 1 (3)c 2 (4)c 2

(1)b 1 (2)c 2 (5)d 3

(2)c 2 (4)b 1

(3)c 2 (1)c 2 (2)d 3 (3)d 3

(2)d 3

Total 5 2 2 5 0 6 3 2 8 3

36

Sections [1,200 m to 1,300 m]

Section 1200 to 1210 1210 to 1220 1220 to 1230 1230 to 1240 1240 to 1250 1250 to 1260 1260 to 1270 1270 to 1280 1280 to 1290 1290 to 1300 Grand total

Score (4)c 2 (5)c 2

(3)b 1 (4)c 2 (5)d 3

(2)c 2 (3)d 3 (4)d 3

(4)c 2 (5)c 2

(3)b 1 (4)c 2

(2)c 2 (3)b 1 (4)c 2

(2)c 2 (3)b 1 (4)c 2 (6)c 2

(2)c 2

(2)c 2 (4)c 2

(2)c 2 (4)c 2 (5)d 3

Total 4 6 8 4 3 5 7 2 4 7

50

(Note) The determination is made for each 10-m section in the example, but the interval needs to be studied in the future.

Type of deform: (2). Cracks Determination category: b Score: 1

Type of deform: (3). Attrition Determination category: c Score: 2

Total score: 1 + 2 + 2 = 5

Total score: 2 + 1 = 3

Total score for the 100 m-section

24

Coloring is done for each score, in order to make the determination categories clearer and make the deteriorated sections visible. Table 4.5: Example of Coloring by Scores for Concrete Open Canal

Soundness Total score Desirable repair works Color S-5 0 to 20 points Not needed Blue S-4 21 to 40 points Observation required Green S-3 41 to 60 points Repair work Yellow S-2 61 to 80 points Reinforcement work Orange S-1 81 points or more Rebuilding Red

Measurement location: Canal Date: , Measured by: 0 to 1,000 ｍ

20 22 24 46 74 85 74 38 38 38 1,000 m to 2,000 m 28 44 74 38 42 20 20 42 25 25 2,000 m to 3,000 m

28 30 46 86 88 42 30 28 30 32 3,000 m to 4,000 m

32 34 36 38 36 38 42 48 46 38

Figure 4.3: Example of Coloring 4.6 Grouping of results Facilities of similar type, structure, deterioration factors and levels are grouped together, in order to determine whether repair works are needed and to compare and study repair work methods efficiently based on the results of function evaluation.

The facilities need to be grouped so that technically feasible repair works would be applied. In the process, the deterioration factors and site conditions that could affect the progress of deterioration in the future need to be fully considered. When a broad range of facilities is considered, the type of facilities, soundness and deterioration factors are taken into consideration, along with the required accuracy and scope of work. Grouping should be rather rough, in view of promoting the progress of studies. Since irrigation and drainage facilities supply agricultural water in each irrigation unit,

Grand total of the score

25

grouping should be done taking into consideration the water intake facilities and water division work for the irrigation network.

Cracks (Soundness S-3)

Grouping for method A

Separation (Soundness S-2)

Figure 4.4: Example of Grouping in Main Canal

Grouping for method B

Figure 4.5: Example of Grouping in Multiple Facilities

Grouping for method D

Grouping for method C

Cracks (Soundness S-3)

Separation (Soundness S-1)

Head work

Main canal

Main canal

26

Chapter 5 Prospecting for Deterioration Empirical formulas are used for prospecting for deterioration, if the deterioration factors are known and the methods for the prospect have been established. If an empirical formula has not been established or it is difficult to specify the deterioration factors due to complication of them, it is desirable to set a standard deterioration curve and correct it by actual measurements made in function evaluation.

The deterioration of irrigation and drainage facilities are often caused by multiple factors, so that prospecting methods for deterioration of irrigation and drainage facilities have not been established even when the deterioration factors can be specified. Therefore, it is desirable to accumulate function evaluation data, and to set a deterioration curve based on the data. In Southeast Asia, however, function evaluation data have not yet been collected and organized sufficiently at the current moment. It is important to conduct prospecting for deterioration appropriately by constantly accumulating and organizing function evaluation data, for selecting the time to implement repair works. Prospecting for deterioration is categorized into a model that focuses on the development process of individual deterioration phenomenon (the individual deterioration model) and a model that focuses on the statistical change of facility soundness (the statistical model). The individual deterioration model is used for detailed prospecting for deterioration. However, it has not been clarified yet how an individual irrigation and drainage facility deterioration, and there is also no sufficient data. Furthermore, more detailed function evaluations of the facilities are needed if the individual deterioration model is to be applied. The types of deterioration can be broadly categorized into the following three groups:

Initial imperfection

Material deterioration

Structural deterioration

Junk Cold joints Internal defects Sand streak Non-progressing

cracks Dry cracks Drying and contraction cracks Thermal cracks

Cracks Preceded by reinforcement corrosion Preceded by cracking Bleeding and separation Rusty liquid Efflorescence Discoloration Attrition Cross-sectional defects

Bending and shear cracks Deflection Deformations Vibration

Figure 5.1: Types of Deterioration

27

The factors and effects of each of the initial imperfection, material deterioration and constructional deterioration are as follows.

Table 5.1: Initial Imperfection Item Factors Effects

Junk

Coarse aggregates are distributed in one place due to material separation during concrete casting, insufficient compaction, leakage of cement paste from the lowest edge of forms, etc.

Many voids are formed, decreasing water tightness and suppressing concrete neutralization. Neutralization and salt injury are easily induced.

Cold joints The concrete is not unified at joints and it creates a discontinuous surface.

The faces with cold joints usually have lower strength. Corrosion could be in induced due to decline in water tightness.

Internal defects Generated by defective construction work, deformed grounds, etc.

When cavity have been formed inside the concrete, decline in durability, neutralization, salt injury and other deterioration factors could be induced.

Cracks by drying shrinkage.

Cracks are generated when the concrete during drying shrinkage.

Thermal cracking Heat of hardening The internal temperature rises due to hydration reaction and the difference of cracks temperatures between inside and surface of concrete become large cracks generate due to the difference in expansion ratios. Concrete of small water-cement ratio and thick concrete are more likely to develop the passing-through cracks because of lower heat exhalation. Sun heat

The outer surface temperature rises when exposed over a long time to direct sunlight after completion, and the concrete expands to form cracks.

Subsidence cracking The concrete subsides along with bleeding, but concrete around the reinforcement is bound. Cracks develop due to the difference in amounts of subsidence between concrete around the reinforcement and other parts.

The concrete quality is affected only in a few cases, but repairs should be done promptly in order to prevent reinforcement corrosion caused by water and air seeping in from the cracked surfaces.

28

Table 5.2: Material Deterioration Item Factors Effects

Cracks

Neutralization When the water/cement ratio is excessively large or covering on reinforcement is thin, the effects of concrete to suppress neutralization declines, leading to corrosion of reinforcement and cracks. Alkali-aggregate reaction

Aggregates inside the concrete and alkali metal ions contained in the cement react with each other, allowing water to penetrate and cracks to develop.

Since neutralization does not cause the strength of concrete to be lost, damage is very small with non-reinforced concrete. In case of reinforced concrete, cross sections of reinforcement and concrete are decreased due to the reinforcement rusts, so that the durability declines.

Breakdown and separation

The adhesion force on concrete surface declines due to neutralization, salt injury damage and other factors, and concrete is separated gradually from the surface.

Decline in structural durability and falling of concrete mass could result due to insufficiency of cross-section and covering on reinforcement, etc.

Rust Reinforcement rusts due to neutralization of concrete.

Corrosion of reinforcement progresses rapidly when the remnant covering after neutralization falls 10 mm or below.

Efflorescence (free lime)

The water contained in concrete evaporates on the surface, calcium gets dry and white deposit adheres on the surface.

Efflorescence itself does not have any adverse effects on concrete quality. However, it is related to migration of water, so cracks, internal deformation and other deterioration could have generated.

Attrition In canals, the cement portion gets on the surface eroded due to attrition to a point that it can no longer support the aggregates, and in time aggregates could fall out.

Overall strength could be lost due to the decrease in covering on reinforcement and cross-section of members. Insufficient covering could also promote neutralization and corrosion of reinforcement.

29

Table 5.3: Structural Deterioration Item Factors Effects

Cracks

Due to loads greater than the design load or uneven loads, cracks develop almost perpendicular to the member axis at locations where bending moment dominates and cracks develop in slanted directions at locations where shearing stress dominates.

The locations where cracks have developed in structurally vulnerable, so repair, reinforcement and other measures need to be studied in order to secure necessary durability.

Deformation Deformation occurs due to external forces or due to the properties of concrete (drying shrinkage and contraction caused by the temperature rise from hydration reaction, expansion, creep, etc.)

When caused by external forces, cracks by bending and shear as well as deformation could also have developed. The structural strength declines in case of progressive cracks, so prompt measures are needed.

Deflection When deterioration progresses significantly due to structural defects, neutralization, salt injury , corrosion, alkali-aggregate reaction, fatigue, attrition and other factors, the ductility and rigidity of members decline and deflection enlarges. Deterioration of the structure causes its rigidity to decline, and the characteristic vibration could lower as a result. When the characteristic vibration is reduced, the amplitude of vibration increases. This could increase the amount of deflection and lead to a collapse.

The structural strength declines in case of progressive cracks, so prompt measures are needed. Structures that could be affected by vibration include PC tanks, canal bridges, and dam columns.

30

Chapter 6 Repair Works 6.1 Outline of repair works The purpose of repair works is to recover the performance of concrete structures and open canals that are degraded due to progressive deterioration. The selection of repair work methods needs to be based on the results of function evaluations, including estimation of deterioration factors and prospects of deterioration progress.

When implementing repair works, the causes of deterioration and the process of its progress should be fully considered based on the results of the function evaluation. Therefore, it is important to select a repair work method best suited to the purpose. The scope and scale of repair works needs to be determined with considerations given to economy. (See Table 4.2 in Chapter 4 for studies concerning whether repair works are needed) The durable periods mentioned in Table6.1 were the examples in Japan and were cited from Guidelines on Function Preservation of Irrigation and Drainage Facilities. However, daytime is long and the climate is dry during the dry season in Southeast Asia, while precipitation is heavy and erosion caused by flood is significant during the rainy season. The durable period should be determined taking into consideration the conditions in each country. Table 6.1: Examples of Major Repair Works for Concrete Structures

Repair works Deformation Durable period

Repair works for cracks 1. Injection method 2. Filling method 3. Crack covering method

Cracks, water leakage 10 years

Cross-section restoration methods 1. Plastering method 2. Spraying method 3. Mortar injection method 4. Treatment method for

deteriorated portions

Breakdown, separation, cross-sectional breakdown, corrosionof reinforcement

10 years

Joint repair method Water leakage − Adhesion methods

1. Steel plate adhesion method 2. Panel adhesion method 3. Continuous sheet adhesion

method

Cracks, attrition, deflection, breakdown, separation

40 years

Methods for increasing member thickness

1. Concrete thickness increasing method

2. Steel covering method

Deformation, cross-sectional breakdown

−

Re-casting methods 1. Partial re-casting method 2. Overall re-casting method

Deformation, cross-sectional breakdown

30 years

(Note) Cited from Guidelines on Function Preservation of Irrigation and Drainage Facilities

31

6.2 Selecting repair work methods When selecting a repair work method, the purpose and required performance need to be clarified. Repair work methods should be studied in accordance with the following items and flow chart. (1) The purpose and required performance of the repair works should be clarified. (2) The properties of materials used for repair and reinforcement should to be clarified. (3) Consideration should be given to economic efficiency. (4) Maintenance work after the repair works should be simple.

Study on methods and materials

Evaluation on required function Water use performance Hydraulic performance Structural performance Social safety performance

Are required function being met?

Study on repair work methods Requests by facility administrator

Maintenance plan

Implementation of repair works

Conditions for study

Figure 6.1: Flow of Studies on Repair Work Methods

Conforming to the process of progress in performance degradation and deterioration?

Are ease of repair work method and, maintenance and economic efficiency

32

Chapter 7 Calculation of Life Cycle Costs 7.1 Stock management and life cycle costs Stock management aims at reducing the life cycle costs as much as possible, which are the total costs including not only those for facility construction but also for maintenance and scrapping during the expected usage period.

(1) The life cycle costs are calculated based on the scenarios prepared through studies on

repair works, and are compared in terms of the economic efficiency. Specifically, the following procedures should be followed. 1) The costs for repair works, and operation and maintenance required in each year are

converted to the current values based on the social discount rate, for deriving the prices for each scenario.

2) The necessary operation and maintenance costs normally comprise the personnel

costs, minor repair costs that are included in the administrative costs and electricity charges. If there is not much difference in the operation and maintenance costs among the scenarios, the costs may be omitted.

3) The remained value of the existing facilities at the final year in the period

concerned is calculated based on the idea of depreciation, and the life cycle costs are obtained by deducting the remained value.

(2) The specific breakdown of the life cycle costs are as shown below.

1) Survey and design costs: Construction planning costs, design costs, field survey

costs, land acquisition costs 2) Construction costs: construction work costs, environmental measures costs,

inspection costs for construction 3) Maintenance costs: repair costs, operation costs, general administration costs 4) Scrapping costs: dismantling costs

(3) In construction of irrigation and drainage facilities, the facilities have conventionally

been designed to minimize the design and construction costs. On the other hand, it is desirable in the future to design facilities of minimum life cycle costs, including those for maintenance and scrapping. The standard durable period is set for irrigation and drainage facilities. Conventionally, the facilities were basically demolished when they reached the standard durable period. On the other hand, stock management focuses on the values (=function/cost) of the facilities and aims to enhance the values. For example, the facility values would improve if the life cycle costs were reduced or the expected usage period was extended, assuming ,for example, the facility values = expected usage period/life cycle costs.

33

Therefore, the facility values would improve if the expected usage period was extended by providing repair works to cope with the performance degradation, without removing or renewing the facilities.

7.2 Methods to calculate life cycle costs The equation generally used for calculating the life cycle costs is as shown below.

LCC = CI + Σ (CM × Fpw) + CR × Fpw - VR

CI: Initial construction costs CM: Repair work costs (estimated based on survey results on actural repair work

costs, deterioration curve, etc.) CR: Facility demolishing costs Fpw (t): Present value factor (discount factor in the year t)= (1)/(1+i)t i: Social discount rate t: Year during which the cost accrued VR: Remaining value

VR = CI × (1 - number of years passed/durable period) × Fpw＋CM × (1 - number of years passed/durable period) × Fpw

* If (1 -number of years passed/durable period) < 0, then it shall be assumed that (1 - number of years passed/durable period) = 0.

Table 7.1: Present Value Factor of Social Discount rate (Fpw) Year (t) Social discount rate

of ４％ Social discount rate

of 12％ 0 1.00 1.00 5 0.82 0.57 10 0.68 0.32 15 0.56 0.18 20 0.46 0.10 25 0.38 0.059 30 0.31 0.033 35 0.25 0.020 40 0.21 0.011 50 0.14 0.003

(1) Example of life cycle costs calculation

1) From construction to scrapping (VR= 0)

A concrete open canal is constructed at 10 million yen. CI: 10,000,000 (yen) (The durable period is 40 years) Repair works are done at 1 million yen 10 years after the construction.

CM10: 1,000,000 (yen)

(The durable period is 15 years)

t

34

Repair works are done at 2 million yen 20 years after the construction.

CM20: 2,000,000 yen

(The durable period is 20 years) The concrete open canal is scrapped 30 years later at 3 million yen.

CR: 3,000,000 (yen)

The social discount rate is assumed to be 4%. Fpw: 4% LCC = 10,000,000 + 1,000,000 × 0.68+2,000,000 × 0.46 + 3,000,000 × 0.31 = 12,530,000 The life cycle costs of this canal would be 12,530,000 yen.

2) After passage of 30 years from the start of usage (CR=0)

A concrete open canal is constructed at 10 million yen. CI: 10,000,000 (yen) (The durable period is 40 years) Repair works are done at 1 million yen 10 years after the construction.

CM10: 1,000,000 (yen)

(The durable period is 15 years) Repair works are provided at 2 million yen 20 years after the construction.

CM20: 2,000,000 yen

(The durable period is 20 years) The social discount rate is assumed to be 4%. Fpw: 4%

LCC = 10,000,000 + 1,000,000 × 0.68 + 2,000,000 × 0.46 - 10,000,000 × (1-40/50)

× 0.31-1,000,000 × 0 × 0.31-2,000,000 × (1-10/20) × 0.31 = 10,515,000

The life cycle costs after a period of 30 years from the construction of this canal would be 10,515,000 yen.

3) After passage of 10 years from the start of usage. The period of for the life cycle

costs is assumed to be10 to 30 years.(CI=0)

A concrete open canal is constructed at 10 million yen. CI: 0 (yen)(The durable period is 40 years) Repair works are done at 5 million yen 15 years after the construction.

CM５: 5,000,000 (yen)

(The durable period is 30 years) The social discount rate is assumed to be 4%. Fpw: 4%

LCC = 0 + 5,000,000 × 0.82 - 0 × (1-20/30) × 0.46-5,000,000 × (1-15/30) × 0.46

= 2,950,000

35

The life cycle costs after a period of 20 years. After passage ten 10 years from the start of usage of this canal would be 2,950,000 yen.

(2) Social discount rates in Southeast Asia Asian Development Bank assumes the social discount rates to be 10 to 12%. But these are only guidelines for the social discount rate, and it should be determined to suit the conditions in each country. The social discount rate of different countries is shown below as a reference.

36

Table 7.2: Social Discount rate of Different Countries Social discount rate Source

Japan 4% Guidelines on Function Preservation of Irrigation and Drainage Facilitites

Asian Development Bank 10 to 12% Guideline for the Economic Analysis of Project,1997 United Kingdom 8% COBA（Cost – Benefit Analysis） Germany 3% Macro-Economic Evaluation of Transport Infrastructure

Investments, Evaluation Guidelines for the Federal Transport Investment Plan, The Federal Minister of Transport, 1992

Belgium 4% ASSESSING THE BENEFITS OF TRANSPORT, ECMT, 2001

France 8% ASSESING THE BENEFITS OF TRANSPORT, ECMT, 2001

Sweden 4% ASSESSING THE BENEFIT OF TRANSPORT, ECMT, 2001

New Zealand 10% Evaluation Procedure for Alternative to Roading, Transfund NewZealand

(3) Period of study

Currently, the period of study for the life cycle costs is assumed to be 40 to 60 years in Japan. In Southeast Asia, facilities are believed to deteriorate quicker due to the differences in precipitation and sunlight. In addition, as for durable period, it is different by the structure of facility. In case of open canals, the durable periods of lined canal and reinforced concrete canal are different. Therefore, it is likely that the period of study should be shorter in Southeast Asia. It should be determined to suit the conditions in each country and facility.

37

Chapter 8 Examples of Repair Work Scenario Several scenarios for repair works shall be prepared that combine different times and methods of repair works. The life cycle costs are to be compared for each scenario, and the one with the lowest costs shall be selected. The following points should be noted when preparing scenarios.

(1) Repair works shall be implemented while the soundness stays above the lowest control level.

(2) The repair work costs shall be within a feasible budget. (3) The repair works shall be carried out using feasible methods. (4) The period of study of life cycle costs shall be set to suit the conditions in each

country. (5) The social discount rate shall be determined to suit the conditions in each country.

When several scenarios for repair works are compared, a certain period of study should be decided. The repair work scenarios for concrete open canal after a period of 60 years from the start of usage are compared in the following pages. In this case, it is assumed that the soundness of the facility reaches zero if concrete open canal wasn’t repaired from the start of usage.

38

(1) Scenario (1)

A concrete open canal is constructed at 100 million yen. CI: 100,000,000 yen (The durable period is 30 years) Scrap was done at 20 million yen 30 years after the completion

CR: 20,000,000 yen

Reconstruction was done at 100 million yen 30 years after the completion.

CM40: 100,000,000 yen

(The durable period is 30 years) The social discount rate is assumed to be 4% Fpw:4%

LCC (1) = 100,000,000 + 100,000,000 × 0.31 + 20,000,000 × 0.31= 137,200,000

The life cycle costs for scenario 1 would be 137,200,000 yen.

30years

Soundness

0

S-5

Time

60years

S-4

S-1

30years 0 60years

LCC

100,000,000

137,200,000

S-3

S-2

39

(2) Scenario (2)

A concrete open canal is constructed at 100 million yen. CI: 100,000,000 yen (The durable period is 30 years) Repair works are carried out at 40 million yen 20 years after the completion.

CM20: 40,000,000 yen

(The durable period is 25 years) Repair works are carried out at 40 million yen 20 years after the completion.

CM40: 40,000,000 yen

(The durable period is 25 years)

The social discount rate is assumed to be 4% Fpw:4%

LCC (2) = 100,000,000 + 20,00LCC (2)=100,000,000 +40,000,000× 0.46+ 40,000,000 × 0.21

- 40,000,000 × (1-20/25)× 0.10 = 126,000,000 The life cycle costs for scenario 2 would be 126,000,000 yen.

20years

Soundness

0

S-5

時間

60years

S-4

S-2

20years 0 60years

LCC

100,000,000

118,400,000

126,800,000

40years

40years

126,000,000

S-1

S-3

40

(3) Scenario (3) A concrete open canal is constructed at 100 million yen. CI: 100,000,000 yen (The durable period is 30 years) Repair works are carried out at 30 million yen 15 years after the completion.

CM15: 30,000,000 yen

(The durable period is 20 years)

Repair works are carried out at 30 million yen 30 years after the completion.

CM30: 30,000,000 yen

(The durable period is 20 years) Repair works are carried out at 30 million yen 45 years after the completion.

CM45: 30,000,000 yen

(The durable period is 20 years)

The social discount rate is assumed to be 4%

Fpw:4%

15years

Soundness

0

S-5

60years

S-4

S-2

15years 0 60yaers

LCC

100,000,000

116,800,000

126,100,000

45years

30years

130,450,000

131,200,000

30years

45years

S-1

S-3

41

LCC = 100,000,000 + 30,000,000 × 0.56 ＋ 30,000,000 × 0.31 + 30,000,000 × 0.17 - 30,000,000 × (1-15/20) × 0.10 = 130,450,000

The life cycle costs for scenario 3 would be 130,450,000 yen.

Comparison of LLC after a period of 60 years from the start of usage Scenario (1) Scenario (2) Scenario (3) Number of years in usage 60 years 60 years 60 years

Life cycle costs 137,200,000 yen 126,000,000 yen 130,450,000 yen As shown above, the life cycle costs after elapse of 60 years from the start of usage is the lowest with scenario 2.

42

43

The deterioration situation photograph of concrete structure

44

The deterioration situation photograph of concrete structure

Deterioration

situation

Photograph

Slope failure

（Slope is is not

repaired for several

years.

（Tha Ngon district）

Measures are urgently necessary. Slope may be broken more in future.

One of three pumps

is broken.

The pump is not

repaired for several

years.

（Tha Ngon district）

Pumping discharge is not enough compared with the plan.

The damage of

diversion gate.

（Tha Ngon district）

45

Deterioration

situation

Photograph

The sedimentation

of sand

（Way Jepara

district）

Water requirement cannot be

secured.

Luxuriant growth of

the glass

（Way Jepara

district）

Water requirement cannot be

secured.

The damage of

drop.

（Way Jepara

district）

Concrete lining

canal is broken

（Laos）

Dysfunction of flow capacity

46

Deterioration

situation

Photograph

Separation by the

deterioration of the

concrete.

（Laos）

Leakage may occur.

Separation and

attrition

（Way Jepara

district）

Leakage may occur.

Shrinkage crack

（Way Jepara

district）

Leakage from crack is not thought.

Separation of

precast concrete

block lining

（Tha Ngon district）

Leakage may occur.

47

Deterioration

situation

Photograph

（Way Jepara

district）

The continuance inspection is necessary.

The deterioration of

joint.

（Way Jepara

district）

The continuance inspection is necessary.

Junk

Cold joint

48

49

Glossary

50

Glossary Japanese English

アセットマネジメン

ト asset management Asset management generally refers to the

management and operation of financial assets and real estate and other properties. In recent years, it has been used as a generic term representing technological systems and management methods aimed at efficient implementation of public works, etc.

維持管理 maintenance This term refers to the management of facilities to maintain them in a sound state.

改修 improvement This term refers to the restoration of lost functions or addition of new functions.

改築 reconstruction Reconstruction refers to replacing the existing facilities with new ones with the aim of ensuring conventional functions or adding new functions.

灌漑管理移転 irrigation management transfer

This refers to the concept of transferring facility management right to farmers.

管理水準 control level The control level is the range of allowable performance degradation, which needs to be determined taking into consideration the agricultural importance of each facility, environmental and disaster risks, etc.

幹線水路 main canal It is the canal located upstream to branch canals. 基準 criteria The standards by which issues can be judged. 機能 function It refers to the roles to be performed by irrigation

and drainage facilities in accordance with their purposes and requirements.

供用期間 expected usage period It is the period during which facilities are used. 健全度 soundness Soundness means that the conditions of facilities

are normal. 現地調査 field survey, field study The field survey is performed by engineers in the

process of function evaluation, for clarifying the state of deterioration of a given facility.

機能診断 function evaluation This is a concept that combines the functional evaluation survey and functional evaluation appraisal.

機能低下 function degradation The term refers to the loss of functions and decline in performance of facilities or facility systems.

機能保全 function preservation ・ This refers to the process of preventing the loss of functions and decline in performance of facilities or facility systems, or recovering from such loss and decline.

緊急点検 emergent inspection ・ This category of inspection is performed on damaged irrigation and drainage facilities and similar facilities.

グルーピング grouping ・ Facilities of a similar type, structure, and factors and level of degradation, are grouped.

現価係数 present value factor The future costs are multiplied by the present value factor for replacing them at the present costs.

欠損 break-down The term refers to the state in which a part of concrete falls off from the surface due to progress in degradation.

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Japanese English 更新 renewal The term refers to the replacement of the entire

facilities with new facilities. 構造劣化 structural deterioration This refers to the state where the structure has

become deformed due to external forces. コールドジョイント cold joint ・ The cold joint is where concrete that was cast at

different times is not unified and there exist discontinuous surfaces.

残存価値 remained value This refers to the value of irrigation and drainage facilities as assets, after some time has elapsed from the start of usage.

事後保全 post-maintenance ・ The term refers to repair work performed after the performance of facilities has declined below the control level due to degradation and other reasons.

事前調査 preliminary survey The survey is for gathering documents and conducting interviews, performed prior to field surveys for function evaluation.

ジャンカ junk This refers to the condition where concrete did not spread thoroughly during casting, and after the forms are removed, aggregates are found on the surface.

ストックマネジメン

ト stock management This is a generic term referring to technological

systems and management methods aiming to utilize the existing facilities effectively, to prolong the service life, and to reduce the life cycle costs, by implementing function preservation measures based on the function evaluation of the facilities.

水理機能 hydraulic function This refers to the functions of water related to its physical properties.

性能 performance The term refers to the capacity of irrigation and drainage facilities to perform their roles.

性能低下 decline of performance The term refers to the decline in the capacity to perform the expected roles due to progress in degradation, etc.

使用限界水準 working marginal limit This refers to the lowest limit of the properties, below which the use of the facilities would be disabled.

社会的割引率 social discount rate The social discount rate refers to discount rates used by the governments and other organizations.

初期欠陥 initial imperfect The term refers to defects that arise from the planning, design or construction work of the facilities.

対策工事 repair work This refers to the work provided to recover the performance of deteriorated structures and facilities.

耐用年数 Durable period The durable period refers to the expected useful period, up to the time when the facilities no longer perform the necessary functions and cannot be used any more, due to degradation in functions, etc.

たたき Beating by hammer This is a method of surveying whether there is a cavity inside the concrete, by knocking on the concrete surface with a hammer.

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Japanese English 長寿命化 prolongation This refers to actions for extending the remaining

durable period of facilities, by providing function preservation measures based on the results of function evaluation.

中性化 neutralization Neutralization refers to the phenomenon in which the alkaline properties of concrete are lost when the cement-water ratio is excessive, etc. Reinforcement in neutralized concrete is prone to rusting.

沈下 subsidence Subsidence refers to the phenomenon in which structures sink into the ground due to the insufficient supporting strength of the foundation of the structure and other reasons.

通水機能障害 dysfunction of flow conveyance

The term refers to the conditions where the capacity of canals to let the water flow has declined.

点検 inspection This is a generic term for investigating activities aiming to detect if there is any abnormality in structures and members.

定期点検 routine inspection This category of inspection is performed once every year to every several years, to clarify changes in the conditions of facilities.

農業水利施設 Irrigation and drainage facility

This is a generic term referring to irrigation channels, drainage channels, canals, pumping grounds, head works, dams, etc.

農民参加 farmers’ participation This refers to when farmers also assume roles in planning the project, during all the stages of water management etc.

日常管理 daily examination This category of inspection is performed regularly once a day to a week, mainly by visual inspection and other simple methods.

日常点検 daily inspection This category of inspection is performed daily for detecting any change in the conditions of irrigation and drainage facilities.

廃棄 scrap The term refers to removal and disposing of irrigation and drainage facilities whose durable period has expired.

剥離 separation This term refers to the phenomenon in which a part of a concrete structure peels away.

判定基準 criterion for determination This term refers to the standard for categorizing structures based on the degree of deterioration.

評価 Assessment, This term refers to the act of appraising the results of function evaluation surveys.

ひび割れ crack This refers to cracks in concrete. 分水 water division Water division is a structure for adjusting and

distributing discharged water to the flow volume or water level specified for the region.

変状 metamorphose The term refers to all the initial imperfections, damage and deterioration.

補強 Reinforcement It refers to actions for recovering or enhancing structural durability of facilities.

補修 repair It refers to actions for recovering the durability of facilities.

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Japanese English 末端施設 on-farm irrigation facility The term refers to the portion of agricultural

irrigation facilities located along farmlands, such as tertiary canals.

摩耗 attrition The term refers to the state of concrete where the cement portion has eroded away due to friction and aggregates have become exposed.

水管理 water management The term refers to the comprehensive activities encompassing water storage, water intake, water division and water quality preservation in relation to irrigation and drainage.

水利用機能 water use function The term refers to functions for using the water. 目地 joint This refers to the portion where concrete members

that were cast separately are connected. 予防保全 preventive maintenance

measure This term refers to measures that are implemented for extending the durable period of irrigation and drainage facilities economically, with the aim of minimizing the function preservation costs, before the performance required of the facilities declines to a level below the control level and does not allow any more decline in performance.

・ ライフサイクルコ

スト (LCC)

life cycle cost The term refers to the total of the costs necessary for constructing the facilities and those necessary for operation during the expected usage period and repair and other management work, as well as those incurred for scrapping.

臨時点検 extra inspection This category of inspection is performed on irrigation and drainage facilities that were damaged due to external forces, etc.

劣化 deterioration This term refers to changes in members and structures that cause decline of performance of facilities over time.

劣化予測 prospect of deterioration This term refers to the process in which the progress in deterioration is estimated using standard curves derived from statistical data and based on interannual data.