DVC SPEC

ERECTION SPECIFCATION Damodar Valley Corporation, PSR Section, Electricity Department

Volume

3

DAMODAR VALLEY CORPORATION

Erection Specification

PSR Section, Electricity Department

DVC TOWERS

VIP Road

Kolkata - 700054

Phone 033 2355 6043 • Fax 033 2355 9618

ERECTION SPECIFICATION, PSR SECTION, ELECTRICITY DEPARTMENT

Table of Contents

ERECTION SPECIFICATION GENERAL .....................................................................................1

SPECIFICATION FOR ENGINEERING DRAWINGS ...................................................................6

ERECTION SPECIFICATION FOR EARTHING ...........................................................................9

ERECTION SPECIFICATION FOR ELECTRICAL EQUIPMENTS ........................................... 12

ERECTION SPECIFICATION FOR SWITCHYARD LAYOUT & ACCESSORIES .................... 17

ERECTION SPECIFICATION FOR CABLING ........................................................................... 18

ERECTION SPECIFICATION FOR LIGHTING ......................................................................... 22

ERECTION SPECIFICATION FOR LINE ON TOWERS ........................................................... 25

TECHNICAL SPECIFICATION FOR GENERAL CIVIL WORKS ............................................... 48

GENERAL SPECIFICATION FOR CIVIL, STRUCTURAL, ARCHITECTURAL WORKS.......... 67


1

ERECTION SPECIFICATION GENERAL

DAMODAR VALLEY CORPORATION ELECTRICITY DEPARTMENT

VIP ROAD KOLKATA - 700054

1 Scope

This scope covers the specific requirements and services required for erection work.

2 Responsibility

The Contractor shall be fully and finally responsible for proper erection, safe and satisfactory

operation of complete switchyard including all plant and equipment under this scope of work to

entire satisfaction of the Engineer. The work shall be executed in accordance with the directions,

instruction, approved drawings and specification of the Purchaser. On the basis of tender drawings

and specifications, the Contractor shall submit all relevant substation drawings for Purchaser’s

approval. If in the opinion of the Contractor any work is insufficiently specified or requires

modification, the contractor shall refer the same in writing to the Purchaser and obtain instruction/

approval of the Purchaser before proceeding with the work. If the contractor fails to refer such

insufficiencies the same will not be accepted as an excuse for the faulty erection, poor

workmanship or delay in completion. Equipment and materials, which are wrongly installed, shall

be removed and re-installed to comply with the design requirement at the Contractor’s expense, to

the satisfaction of the Purchaser.

Rates for all items of the Price Bid Schedule include all cost involved for the performance of the

complete item considering all parts of the Tender document. In case any activity not covered in the

description of the item in the Price Bid but required for completion of the work as per the Tender

document arises, the same shall be deemed to be included in the said description of the item.

3 Supervision

The Engineer as defined in the GCC, shall have the overall responsibility for coordination of

Contractor’s work and his direction shall be final. Such direction and supervision, however, shall not

relieve the contractor of his responsibility of correctness and quality of workmanship and of other

obligation under the contract.

4 Methods & Workmanship

All work shall be installed in a first class, neat workman like manner by machine/electricians skilled

in the trade involved. Competent supervisors shall supervise the erection work. All details of

installation shall be electrically and mechanically correct. The installation shall be carried out in

such a manner as to preserve access to the other equipment involved.

5 Protection of work

The Contractor shall effectively protect his work, equipment and materials under his custody from

theft, damage or tampering. Finished work where required shall be suitably covered to keep it clean

or free from defacement or injury. For protection of his work the contractor shall provide fencing


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and lighting arrangement. Heating arrangement as necessary or as directed by Engineer shall be

provided. Contractor shall be held responsible for any loss or damage to equipment and material if

any issued to him until the same is taken over by the Purchaser according to the contract.

6 Safety Measures

All safety rules and codes as applicable to work shall be followed without exception. All safety

appliances and protective devices including belts, hand gloves, aprons, helmets, shields, goggles

etc shall be provided by the Contractor. The contractor shall provide guards and prominently

display caution notice if access to any area / equipment is considered unsafe and hazardous. The

contractor shall remain sole responsible for any accident / loss of life / loss of limb etc. for any

person/persons deployed by him and shall arrange suitable action for giving compensation

according to Workmen Compensation act.

7 Co-ordination

The contractor shall at all time work in close co-ordination with Purchaser’s supervisory personnel

and offer them all facility to become familiar with erection and maintenance of the equipment. The

contractor shall arrange his work and method of operation to minimize inconvenience to the other

contractors working on the project in case of any difference of opinion between contractors, the

decision of the Purchaser shall be final and binding on all the parties concerned.

8 Programme & Progress

The contractor shall submit at such times and in such forms as may be requested by the Engineer,

schedule showing the program and the order in which the contractor proposes to carry out the work

with dates and estimated completion time for various parts of the work. The Engineer prior to

starting the erection shall approve such schedules. The contractor shall adhere to the approved

program for all practical purposes. If, for any reason, the work is held up, the contractor shall bring

it to the attention of the Engineer in writing without delay. During progress of work, the contractor

shall submit monthly progress report to CE (TSC), CE (PSR) and such other reports on erection

work and organization as the Engineer may direct. If in the opinion of the Engineer, the progress of

work by the contractor at any stage needs expediting so as to ensure completion of the work within

the stipulated time, the Engineer shall have the right to instruct the contractor to increase his

manpower in appropriate categories and / or working hours per day or erection tools and tackles

and the contractor shall comply with such instructions forthwith.

9 Consumables & Hardware

The contractor shall supply all erection materials, hardware and consumables required for the

completion of erection. The materials shall include but not limited to the following:

1. Consumables Welding rods and gas, oil and grease, cleaning fluids, paints, electrical tape,

soldering materials etc.

2. Hardware Bolts, nuts, plain and spring washers, screws, brackets, supports, clamps,

hangers, saddles cleats, shims etc.

3. Materials, junction boxes, terminal blocks, connectors, ferrules, lugs brass glands, rigid / flexible

conduits, cables, ground wires etc.


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10 Erection Tools & Tackles

The Contractor shall provide all tools, tackles, implements, and mobile equipment such as cranes,

trails, scaffoldings, and ladders etc., which are required for transportation, handling and erection.

Special erection T&P, if any, furnished by the manufacturer along with the equipment may be used

by the Contractor. Such tools shall be returned in good condition to DVC. Purchaser’s tool and

tackles may be used, if and when available, on chargeable basis as per DVC standard. Other tools

to be provided by the Contractor shall include but not limited to the following:

1. Filter machine of adequate capacity for transformer oil treatment.

2. Vacuum pump

3. Compression and cutting tools for ACSR conductor.

4. Pipe bending machine suitable for 3”/ 2 .5”/1.5” IPS Aluminum tubes.

5. Welding machine.

6. Crimping tools for power and control cables.

7. Hydraulic jacks and various lifting and dragging devices and other T&P for handling of heavy

equipment etc.

8. Drilling machine for Earth spikes.

11 Testing Instruments

The major testing instrument that are required to be provided by the contractor are listed below:

1. Insulation tester

(a) Power operated Megger 1KV and 5 KV / 2.5KV grade.

(b) Hand operated Megger 500 Volt and 1000 Volt grade.

2. Hand driven earth resistance Megger - Range 0 to 1/3/30 ohms.

3. Tong tester of suitable range.

4. Multimeters, test lamp, field telephone with buzzer set different gauges.

5. Insulating oil testing set - Range 0 to 60 KV.

6. Lux Meter.

7. Hi-pot testing equipment.

The Contractor will arrange any other test equipment as required.

12 Initial Drawing Requirement

The Contractor shall submit the following drawings after award of work (the basic guidance for such

work shall be provided by DVC):

1. Soil resistivity.

2. Grounding mat details.

3. Spot level drawing of the Substation along with the contour lines

13 Initial Construction Activity


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Certain initial activities to be taken up by the Contractor may be enumerated as follows:

1. Measurement of Spot Level and preparation of contour map of substation site.

2. Preparation of design and detailed working drawings for micro grading of the area.

3. Construction of permanent road inside substation area link road (approach road) and culverts

(if found necessary) and execution of the same as per drawings of DVC.

4. Construction of boundary wall as per DVC drawings.

5. Construction of chain link fencing of the switchyard area and execution of the same as per

DVC drawings.

6. Construction of RCC foundations for equipment and structure as per drawings of DVC.

7. Construction of control building, including false ceiling, plumbing, water supply and sewerage

connection and execution of the same as per drawing and design of DVC.

8. Construction of RCC Cable trench/brick cable trench with RCC cover for cable trench as per

DVC Drawing.

9. Dressing the entire switchyard area by pebbles of 20/40mm diameter after treating the area

with anti-termite. The volume of pebbles required and the unit rate of supply and erection

have to be quoted in the price bid.

10.Preparation, Design, detailed working drawing for Construction of grounding mat for entire

Substation area including Control building. The grounding design and calculation with drawing

along with supporting documents shall be submitted by the Contractor for approval of DVC.

11.Collection of Relevant data those might be required for the above work and the survey work

would be undertaken by the contractor at his own cost. Supply of consumable materials

including cement, steel, stone chips of approved grade shall be arranged for by the

Contractor.

14 Taking Delivery

The contractor shall take delivery of the materials / equipment which are under scope of

Purchaser’s supply (PLCC, CVT, WAVE TRAP etc.) from Purchaser’s stores/ yard/ shed/ Railway

siding. Materials delivered shall be brought to erection site, stored or erected as necessary by

contractor at no additional cost to DVC. Insurance coverage for such materials till handing over is

the responsibility of the contractor at his cost and means. Indents for materials shall be placed

sufficiently in advance (at least 20 days in advance) so as to enable the Purchaser to arrange for

the delivery from stores in time. The contractor shall submit a detailed account of materials issued

to him after completion of work. The excess materials after completion of the job shall be returned

back to the Purchaser’s stores.

15 Opening of Package

All packing cases, packages shall be opened in presence of purchaser’s Engineer of his authorized

representative. Packing cases shall be opened carefully to avoid damage to equipment. Nails and

strips shall be collected separately in boxes and not to be thrown away at random. All packing

materials, timbers, nails and strips shall become property of the Purchaser and shall be delivered to

the Purchaser or disposed of as directed by the Engineer.


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16 Equipment Checking

All equipment, accessories and materials shall be carefully inspected and checked with packing list

and identified with erection drawings. Any discrepancy shall be reported forthwith in writing to the

Engineer and action for rectification / replacement be taken immediately. All parts shall be

thoroughly cleaned, all rust removed and surface polished as required. All cleaned and polished

parts shall be coated with anticorrosive paints where necessary and stored with care, ready for

erection.

17 Installation

Installation work shall be carried out in accordance with good engineering practices and also

manufacturer’s instructions and recommendation where the same is available. Equipment shall be

installed in a neat workmanship manner so that it is de-assembled condition as received at site.

The Contractor shall assemble all those parts, mount and wire up loose equipment, fittings and

accessories and complete with all connections. The equipment to be erected shall be mounted on

steel structures or on foundation as per approved drawings. Contractor will supply and install bolts,

nuts, screws and anchors as required for completing the installation. All erection work shall be

carried out in strict compliance with manufacturer’s instruction and shall include all necessary

adjustment, checks and measurements. All internal wiring of the equipment that has been left

incomplete because of shipping shall be completed by the contractor. The Contractor shall record

results of all erection tests and measurements. The Contractor shall submit copies of those tests

results to the Purchaser for his reference and record.


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SPECIFICATION FOR ENGINEERING

DRAWINGS


ELECTRICITY DEPARTMENT

VIP ROAD

KOLKATA - 700054

1 Scope

This specification covers the requirements for drawings and the use of CAD design and

maintenance projects in DVC facilities. It lays down guidelines and examples for CAD techniques

as they relate specifically to these requirements.

2 General Detailing Guidelines

Each drawing must contain the following details: Title block.

• Drawing dates.

• Revision block.

• Box for initials of draughtsman, designer, checking authority.

• Definitive legends must be placed on each type of drawing. This legend should include all

symbols or designations.

• Drawing co-ordinate system to be provided in border margin.

• Drawing size.

• All line weights and lettering size to be selected carefully and standard size to be used wherever

possible.

• The smallest lettering should be readable at the smallest proposed reduction size.

• Appropriate drawings reference to be indicated.

• All drawings other than schematics and single line drawings must be drawn to scale with the

scale size prominently displayed.

• Clear dimensioning to be used.

• Detail, section or elevation designation and title.

• North arrow for indication of orientation.

• Proper care must be given to the listing of reference drawings to ensure a coherent, concise

pattern.

3 Guidelines for AutoCAD Drawings

Format : The Contractor shall provide all projects in AutoCAD Release 14 or


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AutoCAD 2000 *. dwg format.

Title Block : All drawing shall have a standard title block.

Scale : All information shall be drawn at full scale (1:1).

XRefs : All X-Refs shall be binded to the drawing.

Blocks : All blocks should be created on layer 0, and inserted on the appropriate

layer to acquire all properties of that layer. Block names should never

exceed 8 characters in length.

Layers : All entity colors and linetypes shall be defined by layer. Proposed Layers

for various types of drawings shall be as follows:

Proposed Layers for a CIVIL/SITE Drawing:

Layer List : O (Not Used), BORDER, KEYMAP, SITEPLAN, FTPRINT, SOIL-BOR,

CONTOURS, GRADING, LANDSCP, LAWNSPR, PAVING, WATER, SEWER,

STDRAIN, ELECT, COMM, PHONE, NATGAS, SECTIONS, DETAILS,

DEMOL, NEW, DIMS, TXT, MISC, NOTES

Proposed Layers for a FOUNDATION Drawing:

Layer List : O (Not Used), BORDER, DEMOL, EXISTING, NEW, DIMS, TXT, MISC,

KEYMAP, FDPLAN, SECTIONS, DETAILS, MISC, NOTES

Proposed Layers for an ARCHITECTURAL Drawing:

Layer List : O (Not Used), BORDER, KEYMAP, FLPLAN, DOORS (SWINGS), WDWS,

DIMS, TXT, DEMOL, NEW, SECT, DETAILS, SCHED, INTELV, MISC, NOTES

Proposed Layers for a STRUCTURAL Drawing:

Layer List : O (Not Used), BORDER, KEYMAP, FLPLAN, DEMOL, NEW, BLDGSECT,

STRDET, DIMS, TXT, MISC, NOTES

Proposed Layers for a ELEVATIONS Drawing:

Layer List : O (Not Used), BORDER, KEYMAP, NELEV, SELEV, EELEV, WELEV, DIMS,

TXT, MISC, NOTES

Proposed Layers for a MECHANICAL Drawing:

Layer List : O (Not Used), BORDER, KEYMAP, FLPLAN, DIMS, TXT, WATER, SEWER,

HVAC, SPRINKLER, SCHED, MISC, NOTES

Proposed Layers for a ELECTRICAL Drawing:

Layer List : O (Not Used), BORDER, KEYMAP, FLPLAN, ELEDT, DIMS, DIAG/ SCHEM,

SCHED, MISC, NOTES

The proposed layers are representative and actual drawings may add or omit them as per actual

requirements.


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4 Schematics

Schematics submitted for approval must integrate the circuit details of all the major equipment like

control and relay panels, automation modules (if applicable), circuit breakers, isolators, instrument

transformers, etc.

5 Drawing Approval

All drawings must be submitted for the approval of the Owner as per the instructions in the SCC.

6 Drawing Submission

Submission of drawings shall be as per the instructions given in the SCC.


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ERECTION SPECIFICATION FOR EARTHING



VIP ROAD

KOLKATA - 700054

1 Scope

This specification covers the requirements for design, supply, implementation, testing and

commissioning of a substation earthing system.

2 Standards

Earthing shall be carried out in conformity with this specification and the following specifications/

codes of practice:

1. IS 3043, Code of practice for earthing.

2. IEEE Std. 80, Guide for safety in AC substation grounding.

3. IEEE Std. 81, Recommended guide for measuring ground resistance and potential gradients

in earth.

4. IEEE Std. 81.2, Measurement of impedance and safety characteristics of large, extended or

interconnected grounding system (Part 2).

5. IEEE Std 837, Qualifying permanent connections used in substation grounding.

In case of any conflict between the standards, the instructions of Engineer-in-charge shall be

binding.

3 Earthing Requirements

Earthing and grounding shall hereafter mean the same thing. Earth mat layout in new substations

shall be as per approved design calculations. The design calculations shall conform to IEEE Std

80. The earth mat in existing substations will be an extension of the existing layout.

The grounding system grid shall consist of a network of bare conductors buried in the earth to

provide for grounding connections to grounded neutrals, equipment ground terminals, equipment

housings, and structures and to limit the maximum possible shock current during ground fault

conditions to safe values. If the calculated mesh and step voltages of the grid design are below the

maximum acceptable values for touch and step voltage, then the design is considered adequate.

The ground grid shall encompass all of the area within the substation fence and extend at least

0.91 meter (3.0 feet) outside the substation fence. A perimeter grid conductor should be placed

0.91 meter (3.0 feet) outside and around the entire substation fence including the gates in any

position.

All necessary M.S. rods, G.I. flat etc. and all other grounding materials are under the scope of

contractor’s supply. Excavation and refilling of earth necessary for laying underground earth grid

shall be the responsibility of the Contractor.

M.S. rod of 40mm diameter for grounding mat should be buried a minimum of 0.46M to 1.5M below


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final earth grade (excluding crushed rock covering). In soils that are normally quite dry near the

surface, deeper burial may be required to obtain desired values of grid resistance. Spikes are to be

installed at grid corners and at junction points along the perimeter. Spikes must be at least 2.5M

long and should be installed such that the top of the spike is at least 0.05M below grade and

bonded to the ground grid. The ground mat conductors crossing each other should also be welded

at the crossing points. Wherever the ground mat conductors cross the trenches, they should be

suitably bent and taken at least 300mm below the trench floor level. Wherever copper to steel joints

are encountered the same should be brazed. No ground mat conductor should pass through any

foundation and in the event of such cases, it should surpass the foundation. Ground conductors

should be laid slack to prevent their being readily broken.

Metal bodies of equipment and assemblies including all structures are to be earthed at two different

points with two separate G.I. strips from ground mat. Grounding bolts of the apparatus should be

used for grounding. No fixing bolts of the apparatus will be used for grounding. All contact surfaces

shall be thoroughly cleaned to ensure better contact and free from oxidation. All welding points

above ground level should be covered with bitumen compound. The following shall be earthed:

• Transformers, CT/PT neutrals.

• Lightning arrestors.

• All switchgear, their earth buses, bus duct.

• Motor frames.

• Non-current carrying metallic parts of electrical equipment such as switchgear, racks, power and

instrument panels, cable trays, pipes, conduits, terminal boxes etc.

• All fences, gates/enclosures housing electrical equipment.

• All steel structures, rails etc including bonding between sections.

• Shield wire.

• Structural steel and columns.

• Lightning mast, poles.

• Lightning rods.

• Tanks and vessels containing flammable materials.

The neutral of power and auto transformers shall be directly connected to two pipe electrodes in

treated earth pits as per IS. The pipe electrodes shall be buried in cement concrete pit with a cast

iron cover with a cast iron frame. All accessories associated with the transformers such as cooling

banks, radiators etc shall be connected to the grounding grid through a minimum of two points.

Fences within the substation shall be earthed by connecting the fence-posts through G.I. strip to

ground mat at approx. 10 meter interval and gate leaf should be grounded by flexible copper/

aluminium braid.

Each Lightning Arrestor and Capacitor Voltage Transformer shall be connected to a separate

electrode located as close as possible to it and within the fenced area for each set of arrestors.

The Contractor shall erect the Lightning mast with spikes to be supplied by Contractor as per

approved drawings. The protection shielding angle is 30o to 45o as per CBIP standard.

The shield wire shall be connected with the main ground mat solidly and not through supporting


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steel structures.

The Contractor shall erect the grounding mat as per the approved drawings complete with

grounding of all electrical equipment, steel structure etc. (excavation and back filling for such

grounding shall be performed by the Contractor). All cable trays/ racks/ ladders/ cable and boxes/

conduits/ electrical equipment (such as motors, switchboards, panels, junction boxes, etc.) shall be

effectively grounded with 50 X 6mm GI flat or suitable size GI conductors. All the ground

conductors should be painted black for easy identification. If any equipment does not have any

provision of grounding pads, contractor shall drill and tap holes and provide bolts, spring washers

for connection. Equipment ground connections shall be coated with anti-corrosive paint.

After connecting the ground mat with all spikes, the resistance of the mat should be measured at

several points and if the resistance is found to be more than 0.5 ohm, additional spikes shall be

driven into the soil to bring down the value and the modification should be indicated in the drawing

and also to the Owner.

4 Tests

Resistance of individual electrodes shall be measured after disconnecting it from the grid.

Earthing resistance of the grid shall be measured after connecting all the electrodes to the grid. The

resistance between any point on the metallic earth grid and the general mass of earth shall not

exceed 1 ohm.

The resistance to earth shall be measured at the following:

1. At each electrical system earth or system neutral earth.

2. At each earth provided for structure lightning protection.

3. At one point on each earthing system used to earth electrical equipment enclosures.

4. At one point on each earthing system used to earth wiring system enclosures such as metal

conduits and cable sheaths or armour.

5. At one point on each fence enclosing electrical equipment.


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ERECTION SPECIFICATION FOR ELECTRICAL

EQUIPMENTS



VIP ROAD

KOLKATA - 700054

1 Scope

This specification covers the requirements of installation, testing, commissioning of electrical

equipment.

2 Transformers

2.1 Handling

Newly procured transformers shall normally be shipped from manufacturer’s works with core and

coil submerged in oil/ Nitrogen filled tank. All other accessories such as oil bushing, coolers etc.

shall be shipped separately. Insulating oil required for the complete transformer and coolers with

about 10% excess quantity shall be furnished in separate sealed containers.

2.2 Placement & Assembly

To ensure that there has been no damage during transit, the transformer(s) must be checked for

signs of damage particularly in the following areas:

1. tank sides and cooling tubes for signs of denting

2. protruding tubes for signs of bends

3. oil sight glass for signs of cracks

4. bushings for signs of cracks

5. leakage along welds

All power transformers shall be placed after grouting rails over concrete foundations. The

transformer shall be leveled, aligned and checked for free movement on the rails. Stoppers shall be

clamped to the transformers immediately to prevent any movement.

All accessories like radiators, cooling fans, valves, conservator tanks, explosion vent pipe or

pressure relief valve, bushings and other devices shall be cleaned and tested thoroughly before

fixing on the transformer.

All the connections for CTs, bushings and other wiring shall be checked for tightness and

correctness before tightening all the bolts of the top cover.

Before filling up with oil, transformer should be fitted with all accessories like valves, gauges,

thermometers etc and these shall be made oil tight.

2.3 Topping up

Transformer oil packed in drums must be checked for oil spills and filtered prior to transformer oil


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filling operation.

Oil samples should be taken from each drum and tested for determination of dielectric strength. All

tests conducted on the oil must be in accordance with IS:335 and IS:6792 latest editions. The oil

should also be tested for acidity in accordance with the method prescribed in IS:1866.

Oil should be filled through a streamline oil filter using metal hose. The transformer tank should be

filled through the bottom drain valve. The rate of oil flow should be reduced when the oil level

reaches the top cover.

Sufficient time should be allowed for oil to permeate the transformer so that no air pockets are left

in the tank. To ensure this all air vents must be kept opened. Those that cannot be kept open

continuously must be opened regularly to ensure that trapped air is allowed to escape. Air

accumulation in the Bucholz relay should be released regularly.

2.4 Drying out

Drying out of the transformer shall be carried out strictly as directions of the manufacturer. The IR

values obtained after completion of the drying out process shall be submitted to the Purchaser for

future reference.

2.5 Pre-commissioning Check List

Before commissioning any transformer, the following points shall be verified:

1. That all the accessories have been fixed properly and transformer body and neutral are

properly earthed.

2. That the oil level in the transformer conservator tank and all the bushings is up to the

marked point and the oil has been tested for dielectric strength and acidity.

3. That the silica gel is in reactivated condition. The breather pipe is clear from any blocking

and contains oil up to the proper level.

4. The pressure relief valve has been cleaned of all dirt and that the operating indication and

switches are operating correctly.

5. That the operation of on-load tap changers on all the tap positions is satisfactory. The

mechanical parts of the on-load tap changer are lubricated. Motor IR values are

satisfactory. The tap position mechanical indicator on the transformer and tap position

indication meter on the control panel shoe the same tap positions. Tap changer limit

switches are operating correctly.

6. That Buchcholz relay has been tested and checked up for any restriction in movement of

the floats.

7. That all the metering equipment has been tested. Polarity test of transformer windings are

OK. Phase sequence and connections have been checked for proper vector group.

8. That the ratio test and winding resistance on all tap positions tally with the manufacturer’s

test reports.

9. That the winding and oil temperature thermometer pockets contain oil. That winding and oil

temperature settings on dial gauges are OK.

10. That the transformers fitted with fans for forced air cooling have been checked for automatic

starting and stopping and fan air displacement has been verified.


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11. That the simulation tests for all the alarm, annunciation and trip circuits have been

checked.

12. That the insulation resistance of all the control circuits and IR value of transformer windings

and all the incoming and outgoing cables have been checked.

13. That all the valves in the cooling system and valve between the Buchcholz relay and the

conservator tank is in open position.

3 Circuit Breakers

SF6 circuit breakers would be mounted on steel support structure. The Contractor will transport the

breaker complete with structure to site for erection. Complete assembly, proper alignment, and

installation of breakers with individual compressor unit, control cubicle and necessary connection

for smooth local and remote operation as per approved drawing is the also within the scope of work

of the contractor. The work includes but is not limited to the following:

1. Loading and transportation of the equipment with structure from manufacturer’s premises to

site and unloading the same.

2. Complete checking of the equipment and structure at site and intimation the owner with

inspection report for repair / replace the damaged parts and record of the short supply items.

3. Preparation of procedure for erection to be followed.

4. Assembly, proper alignment and complete erection along with structure, control cubicle,

compressor unit piping and other accessories for smooth mechanical and electrical local and

remote operation as per approved drawing. Necessary connection of breaker terminals to bus.

4 Isolators

3-pole, 245KV, 145KV and 36KV Isolators with/without earth switches complete with accessories

are under Contractor scope of supply. All the above isolators will be mounted on GI structures. The

structures will be fabricated as per drawings supplied by the Owner. The work includes but is not

limited to the following:


2. Supply and erection of support structure.

3. Assembly, proper alignment and complete erection along with structure, control cubicle,

insulators and other accessories for smooth mechanical and electrical operation, necessary

connection of switch terminals to bus.

4. Grounding of the structure as per approved drawing.

5. Testing, commissioning and putting the equipment into commercial operation.

5 Lightning Arresters

198KV, 120KV and 36KV gapless Zinc oxide type lightning Arresters each with insulating base,

surge counter with leakage current measurement device will be mounted on GI structures as per

approved drawing. The steel structures are under the scope of the contractor’s supply as per

drawings supplied by DVC. Complete installation, testing and commissioning of the equipment is

the responsibility of the contract. The work includes but is not limited to the following:


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1. Loading and transportation of the equipment from manufacturer’s premises to site.

2. Complete checking of the equipment and intimating the owner with the inspection report for

repair/replace the damaged parts and record of the short supply items.


4. Supply and erection of support structure as per approved drawing.

5. Assembly, proper alignment, and complete erection of Lighting Arrestor with insulating base,

surge counter and leakage current meter along with necessary connection of LA terminals to

bus bars.

6. Grounding of the structure and equipment as per approved drawings.

7. Testing, commissioning and putting the equipment into successful commercial operation.

6 Instrument Transformers

All Current Transformers are to be mounted on GI support structures (to be supplied by the

contractor) with a centrally structure mounted junction box for wiring. Termination of each pole to

the junction box is within the scope for the contractor as also is complete installation, testing and

commissioning of the equipment. The work includes but is not limited to the following:

1. Loading and transportation of the equipment from manufacturer’s premises site and unloading

the same.

2. Complete checking of the equipment and intimating the owner with inspection report for

repair/replace the damaged parts and record the short supplied items.



5. Assemble proper alignment and complete erection of the equipment necessary connection of

CT terminal to bus.

6. Grounding of the structure and equipment as per approved drawings.

7. Testing, commissioning and putting the equipment into successful operation

7 CVT & Wave Trap

Coupling capacitors will be mounted on steel structure and wave traps would be strung at gantry/

truss structure. The steel structure for the Capacitor Voltage Transformer (CVT) will be fabricated

as per drawing to be supplied by DVC. The work includes but is not limited to the following:


2. Assemble proper alignment and complete erection of the Capacitor voltage transformer and

mounting of wave trap at Gantry/ truss and stringing as required.

3. Grounding of the Capacitor voltage transformer as per approved drawing. Testing,

commissioning and putting the equipment into successful operation.

8 Outdoor Boards, Marshalling Kiosks etc.

Erection will be as per approved drawings. Alignment, grouting/ fixing, mounting and connection

etc. of loose supplied items/ components with necessary grounding will be done by the contractor.


16

9 Control & Relay Panels

All alignment, levelling, grouting, anchoring, adjustment shall be carried out in accordance with

manufacturer’s instruction and / or as directed by Engineer. Mounting and connection of loose

supplied relays, instrument and accessories, adjustment of operation mechanism of components, if

necessary, are to be done on the panels. The panels should be earthed at two extreme points. All

connections in the control boards shall be completed, checked and adjusted to ensure safe and

satisfactory operation of the equipment. In the event of some modification of wiring of equipment

becoming necessary due to certain revision(s) of control scheme for safer and smoother operation,

the contractor have to implement the same without any additional charge to DVC.

10 Battery & Battery Chargers

The cells of the station lead acid cells will be furnished in dry and uncharged condition along with

mounting racks, connecting accessories, insulators etc. and electrolyte in separate container.

The cells shall be erected on wooden stands/racks and insulators supplied by the manufacturer of

the batteries. Electrolyte shall be filled as per manufacturer’s instructions. Inter-row connections

shall be made with the leads supplied by the manufacturer. Supervision for preparation and filling of

electrolyte, terminal connections etc shall be carried out by the manufacturer of the batteries.

Charging, discharging and recharging shall also be carried out under the supervision of the

manufacturer. Lamp/ resistance bank shall be provided by the Contractor.

The above will be installed in separate rooms of the control building.


17

ERECTION SPECIFICATION FOR

SWITCHYARD LAYOUT & ACCESSORIES



VIP ROAD

KOLKATA - 700054

1 Layout

The arrangement of the various bay equipment shall be as per Owner supplied layout diagrams.

The Contractor shall check the safety, phase to phase and phase to earth clearances of all

equipment in the switchyard to ensure that minimum distances as specified in IEC 60071 are met.

If any of the minimum distance criteria are not met, this should be brought to the notice of the

Owner immediately.

132kV system with one main bus and one transfer bus shall have the following characteristics.

Normal bay width shall be 12.5M and the width of the bay on either side of the bus section isolator

shall be 13.5M. The phase to phase spacing shall be 2.7M. The elevation from TOG of the 132kV

truss stringing point, A-frame stringing point and pipe bus shall be 13M, 9M and 5.3M respectively.

Bus support and isolator insulator shall be solid core type. One AC junction box and one CT

junction box shall be provided in each bay.

2 Disc Insulators

Insulator string shall include bolts, nuts, washer, shackles, yokes, clevises, dead end fittings etc.

Single suspension insulator set of 9 discs and 10 discs tension insulator set shall be used in the

gantry for 132kV line entry. Single tension insulator set of 11 discs shall be used for stringing of

132kV Main and Transfer bus.

3 Spacers

Spacers shall conform to IS 10162. The spacers are to be located at a spacing of 2.5M to limit the

short circuit forces as per IEC 865. No magnetic material is to be used in the fabrication of spacers

except for GI bolts and nuts. The design of spacers shall be such that the conductor does not come

in contact with any sharp edge.

4 Aluminium Tube Busbars Welding of Aluminium tubes is not envisaged in the layout of the switchyard. Standard lengths of

Al. tubes can be used without welds throughout the switchyard. However if this should become

absolutely necessary this shall be limited to one weld per span. The procedure for welding shall be

subject the approval of the Owner. Material of the welding sleeve shall be of the same material as

the Aluminium tube. Bending of Aluminium tube shall be done with the help of a bending machine

through cold bend process only.

Corona bells shall be provided whenever the pipe bus extends beyond the clamps and on free

ends. The end caps or bells shall be so shaped that the loss due to electrostatic discharge is

reduced and ingress of moisture is minimised.


18

ERECTION SPECIFICATION FOR CABLING



VIP ROAD

KOLKATA - 700054

1 Scope

This specification defines the requirements for installation, testing and commissioning of a cabling

system for switchyard and substations.

2 Standards

The work shall be carried out in conformity with this specification, approved drawings and

instructions of Engineer-in-charge or his authorised representative.

3 Materials Requirement

Supply of the racks, trays and ladders as per approved drawings is covered within contractors

scope of supply and to be erected parallel to trench / building walls and floors except otherwise

mentioned in the approved drawings. The steel for above is under contractor’s scope of supply.

The contractor will provide embedded steel inserts in wall of the trenches or have to secure them

by welding to these inserts. As far as practicable, the cable racks shall be supported from one side

only in order to facilitate installation and maintenance of cables from the other side / middle.

Sufficient spacing shall be provided between racks to permit adequate access for installation and

maintenance of the cables.

The trays shall be either prefabricated hot dip galvanised sheet steel trays or site fabricated angle

iron trays as specified. Prefabricated hot dip galvanised sheet steel cable trays shall be used for a

maximum support span of 2000mm unless design is approved for larger span. For requirements of

larger than 750mm width two trays shall run side by side. Cable trays shall be suitable for a cable

weight of 50kg/meter running the length of the tray. Minimum thickness of sheet steel shall be 2mm

and galvanizing deposition shall be 86 microns minimum.

4 Cable Storage & Handling

Cable drums shall be stored on hard and well-drained surface so that they may not sink. In no case

the drum shall be stored on flat i.e. with flange horizontal. Rolling of drums shall be avoided as far

as practicable. For short distance, the drums may be rolled provided they are rolled slowly and in

proper direction as marked on the drum. In the absence of any indication, the drums may be rolled

in the same direction as it was rolled during taking up the cable. For unreeling the cable, the drum

shall be mounted on jacks on cable wheel. The spindle shall be strong enough to carry the weight

without bending. The drum shall be rolled on the spindle slowly so that the cable should come out

over the drum and not below the drum. While laying cable, cable rollers shall be used at an interval

of 2000mm. A gang of people positioned in between roller over a suitable distance shall push the

cable over the roller. Cable shall not be pulled from end without having intermediate pushing

arrangement. Bending radius of the cable during installation shall not be less than what is specified

by the manufacturer.


19

5 Cable Laying

Cables shall include power, control, lighting and communication cables, which shall be laid in

trenches, cable trays or conduits as detailed in the relevant drawings and cable schedules.

Erection of cable trays as required shall be the responsibility of the contractor. All tray levels shall

be checked after erection and marked in as built drawings. Cable routing given in the layout

drawing shall be checked at site to avoid interference with structures, heat sources, drains, piping,

air-conditioning duct etc and minor adjustments shall be done to suit the site conditions wherever

deemed necessary without any extra cost.

High voltage, medium voltage and control cables shall be separated from each other by adequate

spacing or run through independent trenches or cable trays as applicable.

All communication cables shall run on instrument trays/ducts/trenches. Wherever these are not

available, cables shall be taken in a separate trench with a minimum clearance of 300mm away

from electrical trench and communication cable shall cross power cables at right angles.

All cable routes shall be carefully measured and cables cut to the required lengths, leaving

sufficient length for final connection of the cable. The contractor shall ascertain the exact

requirement of cable for a particular feeder at site. All interference with structure, foundation,

pipelines is to be avoided.

As far as is possible, cables shall be laid in complete, uncut lengths from one termination to the

other.

Cables shall be neatly arranged in the trenches/trays so that criss-crossing is avoided.

Arrangement of cables within the trenches / trays shall be the responsibility of the Contractor.

Cable shall generally be installed in ladder type fabrications, racks or trays. Cables laid on

trays/racks/ladders shall be neatly dressed and clamped at intervals of 1500mm and 900mm

horizontal and vertical cable runs respectively. The cable racks shall be supported in general at a

suitable span (preferably 750mm apart). Clamps for multicore cables shall be fabricated out of 25 X

3mm aluminium flats. All power cables shall be clamped individually and control cables shall be

clamped in groups of three or four cables. All single core power cables shall be held in trefoil

formation and suitably clamped with 25mm wide 14 SWG Aluminium strips or fiber glass mould

pieces of appropriate quality and sizes prior to laying of cables inside both indoor and outdoor

trenches.

6 Cable Tags & Markers

All power and control cables shall be of continious lengths without intermediate joints. Each cable

shall be tagged with numbers that appears in the cable schedules. Cable shall be tagged at their

entrance and exit from any equipment, junction box. The tags shall be of 2mm thick, 20mm wide

aluminium pieces of suitable length with the cable number punched on it and securely attached to

the cable by not less than two turns of 16SWG, G.I. wire.

7 Cable Termination & Connection

The terminations and connection of cables shall be done strictly in a accordance with

manufacturer’s instructions, erection drawings and / or as directed by the Engineer. The work shall

include all clamping, fitting, fixing, soldering, taping, compound filling, cable jointing, crimping,

shorting and grounding as required for the complete job. All equipment, tools required for the

complete job all equipments, tools required for such operations shall be of contractor’s procure-


20

ment under this specification.

All PVC cables upto 1.1kV grade shall be terminated at the equipments by means of compression

type cable glands and crimping type lugs. The contractor shall put ferrules on all control cores in all

junction boxes and at all terminations. The ferrules shall carry terminal number as per drawing. All

ferrules shall be of coloured plastic type.All unused spare cores of control cable shall be neatly

bunched and ferruled with cable tag at both ends.

All cable entries shall be through bottom only. All switchgear and panels shall have undrilled blank

bottom plates for cable entry. Contractor shall drill holes for fixing glands wherever necessary.

Where threaded cable gland is screwed into threaded opening of different size, suitable galvanised

threaded reducing bushing shall be used. Cables shall be taken through glands into the panels.

The individual cores shall then be dressed and taken along guide ways and terminated at the

equipment terminals by means of crimped type solderless connectors of Dowell make or approved

equivalent.

All temporary ends of cables must be protected against dirt and moisture to prevent damage to the

insulation. For this purpose, ends of all PVC insulated cables shall be taped with an approved PVC

or rubber insulating tape.

Furnishing of all consumable materials such as soldering materials, electrical tape, sealing material

as well as cable jointing kits shall be included in the Contractor’s offer. All cable entry points shall

be properly sealed and made vermin and dust proof. Unused openings should be effectively

closed. Sealing work shall be carried out with approved sealing compound having fire withstand

capability for at least three hours. Cost should be included in Erection cost.

8 Cable joints

Cables shall be installed without joints as far as practicable. If, however, joints become necessary,

they shall be made by qualified cable jointer and strictly in accordance with manufacturer’s

recommendation. Cable jointing kits for all cables shall be supplied by contractor. Responsibility of

proper termination shall lie with the contractor. Guarantee at termination shall also have to be given

by the contractor.

The location of the cable joints, if any, shall be clearly indicated with cable marker with an

additional inscription ’Cable Joint’. The contractor shall furnish and install all tags and markers

stated above. For buried cable, the marker shall project 150mm above ground level and shall be

spaced at interval of 30 M and at every change in direction.

9 Laying of 66kV Cable

38/66kV Cable shall be laid as per supplied drawings and directions given herein. The drums

should be loaded and unloaded at site by means of crane of adequate capacity. Where crane is not

available suitable tripod can be used alongwith chain pulley block of adequate capacity.

The cable is to be laid direct in the ground at a depth of about 1.2 meter, with bedding sand placed

in the immediate vicinity of the cables. The trench should be dug so that the width of the bottom is

approximately 1 meter and the top of the trench is at least 100 mm more than that of the bottom.

Care should be taken that no bricks or stones or similar elements are hanging or similar elements

are hanging from or protruding out of the walls of the trench. Both sides of the trench should be

kept clean from any materials like excavated earth and should be kept away from the edge of the

trench by a minimum distance of 500 mm. A bedding of sand is to be provided at the bottom of the


21

trench including supply of sand 75 mm. the cable is to be laid of cable on sand bedding so that the

depth from the ground surface to the top of the cable is approx 1.05 meter as per IS 1255. First

class brick 2 sets of 24 Nos. per meter are to be placed on both sides of the trench and top. Sand

is to be filled over the top of the cable inside brick protection. Balance portion of the cable trench to

be filled with earth as required including ramming, dressing and leveling as per the requirement

Concrete markers are to be placed at 30 mtr distance just above the cables to give warning of the

presence of the cables and to ensure a measure of mechanical protection. The markers must be

pre-cast reinforcement concrete slab of proper quality made of cement, sand and stone chips in

the proportion of 1:2:3 and 0.8% steel rods with plastering, embossing symbol (DVC 66 KV

CABLE) grouting with cement concrete. Dimension of the cable marker will be 1000 x 300 x 100

mm thick with top round shape.

Sand used for backfill must possess a satisfactory particle size distribution to give acceptably low

thermal resistance. It is desirable to use sands having the highest value of density after placement

of cable in a cable trench.


22

ERECTION SPECIFICATION FOR LIGHTING



VIP ROAD

KOLKATA - 700054

1 Scope

The scope of this specification is restricted to the erection, testing and commissioning of the lighting

system.

2 Standards

The work shall be carried out in conformity with this specification, the codes of practice of the

Indian Standards Institution and the following rules and regulations:

1. Fire Insurance Regulations

2. Indian Electricity Act and Rules.

3 General

The lighting fixtures in the substation are to be fed from lighting panel and group controlled from

local control stations. Lighting wiring between panel and lighting fixtures shall be done by PVC

insulated 3-core (phase, neutral and earth) armoured cable for hazardous areas. Lighting fittings in

buildings shall be fed from lighting panels. Wiring in the building shall be done by means of 3-core

Aluminium conductor PVC insulated, armoured cables or PVC insulated copper conductor wires in

conduit of size 1 inch or Metsec channel as specified. All joints of conductors in switch boards /

junction boxes / fittings shall be made only by means of approved connectors. Bare or twist joints

are not permitted anywhere in the wiring system. Cost towards connectors is deemed to have been

included in wiring.

The lighting layout proposed by the Contractor shall indicate locations of lighting fixtures with

precautions taken in order to avoid interference with piping or other mechanical equipment and

also the level of illumination achieved.

Lighting fixtures located in outdoor area shall be near panel boards and other equipment requiring

good illumination.

Socket outlets in switchyard areas shall be approximately 1200mm above finished grade and

300mm above grade in office area. Lighting panel shall be mounted such that the top of the panel

is not more than 2000mm above finished grade.

Fixtures shall be firmly supported from the structures. Support clamps etc. may be bolted or welded

to existing steel work or metal inserts. In case of concrete structures where metal inserts are not

available, fixtures will be fixed to or supported from concrete structures with the help of anchor

fastners.

All hardware shall be galvanised or zinc passivated. Cables shall be group cleated to structure by

using galvanised strip cable clamps or run in cable trays wherever available.

Main runs of wiring from lightning panels and tappings to individual fixtures shall be in sizes as


23

specified in the equipment specification.

The light fittings for switchyard illumination shall be mounted on Gantry structures and Lighting-

cum-Lightning Mast at a height of approx. 13.0 Meter.

The street light fittings shall normally be fitted on swagged type tubular pole of suitable height but

not more than 11.0 Meter.

Indoors light fittings shall be either ceiling mounted or recess mounted (where false ceiling is

provided). The false ceiling shall normally be at a height of approx. 3.1 M from floor level. The exact

mounting height shall, however, depend on the availability of mounting space. Configuration of

supporting structures, final height of ceiling and false ceiling of the approved control room building

drawing and other related criteria which will be finalised at the time of approval of final design.

4 Conduit System

Surface conduit system of wiring shall be adopted. Suitable pull boxes or inspection type fittings will

be used to facilitate drawing of wires.

Threaded type conduit fittings shall be used. Conduit ends shall be free from sharp edges or burrs.

The ends of all conduits shall be reamed and neatly bushed. In order to minimise sweat

condensation inside the conduit system, all outlets shall be properly drained and ventilated in such

a manner so as to prevent entry of insects. Conduit connection to outlet boxes shall be by means

of screwed hubs or check nuts on either side.

The outer surface of the conduit pipes including all accessories forming part of the conduit system

shall be adequately protected against rust, particularly when such system is exposed to the

weather. Bare threaded portion of the conduit pipe shall not be allowed unless such bare threaded

portion is treated with anti-corrosive preservative or covered with appropriate plastic compound.

Conduits for each sub-circuit or sub-main will be erected before the PVC cables are drawn in and

all cables will be led back to the terminal points and no tape or any other type of cable joints will be

done in part of the wiring system i.e. in the middle of a running conduit. The number of wires drawn

in each conduit should be such that at a later date removal or replacement of any wire can be done

without any difficulties. The total wires in a conduit shall never cover more than 40% of the inside

area. The Tenderer should indicate the numberand size of conductors proposed to be run through

different sizes of conduit.

Conduit pipes shall be fixed by 14 gauge GI saddles on 25 X 6 mm GI saddle bars at an interval of

not more than 25cms. Saddles shall be fixed on either side of couplers, bends or similar fittings, at

a distance of 30mm from the center of such fittings.

Wiring for exhaust fans shall be terminated in ceiling roses / receptacles and the connection from

ceiling rose / receptacle to the exhaust fan shall be by means of a flexible cord equivalent in size to

the main run of wires.

After erection, the entire conduits system shall be tested throughout for mechanical and electrical

continuity and shall be permanently connected to earth by means of earthing clamps in accordance

with the Indian Electricity Rules. An as-built conduit layout drawing shall be submitted by the

Contractor.

5 Building Lighting

All flourescent lighting fittings shall consist of chokes, starters and capacitors. The fittings shall be


24

of high power factor type and shall be supplied with white light flourescent tubes. Other lighting

fittings shall be supplied with 250V incandescent lamps. Lighting fittings shall be supplied complete

with cable glands wherever applicable. Fixtures shall be firmly supported from structures. Support

clamps etc. may be bolted or welded to the existing steel works or metal inserts. In case of

concrete structures where metal inserts are not available, fixtures having weight of up to 2.5kg shall

be supported by minimum two numbers nylon sleeve anchors. All supports shall be thoroughly

cleaned and painted in an appropriate colour to suit the fixture.

In the case of false ceilings employing minimum tee grid system, fixtures shall be supported from

true ceiling. Exact location of fixtures shall be finalised in consultation with air-conditioning

Contractor. Wiring above false ceilings shall not be left loose and shall be supported along the

structures / ceiling. To facilitate easy maintenance ‘looping back system’ of wiring shall be followed

throughout.

All wires in conduit shall be colour coded as specified. Each circuit shall have independent phase,

neutral and earth wire. Unless otherwise specified, insulated conductors of AC supply and DC

supply shall be bunched in separate conduits.

Building conduit lighting wiring shall consist of the part involving work necessary for wiring the

lighting panel with the switch boards and the part involving wiring the various fixtures from the the

switch boards.

6 Street Lighting

Street lighting poles shall be installed at a distance of 300mm from the edge of the walkway of the

road. Each pole shall be earthed by connecting it to the substation earthing with 3/8” GI wire rope

or equivalent.

Street lighting shall be done with HPMV lamps as specified in the equipment specification. They

shall be mounted on steel tubular poles. These poles shall be supplied with base plate and

grouted. The street lighting poles shall be painted with one coat of primer and 2 coats of aluminium

paint. The second coat of aluminium paint shall begiven just before handing over of the installation.

7 Mast Lighting

Mast lighting shall be done with HPMV lamp fixtures mounted on the lighting -cum- lightning masts.

The number of fixtures shall be as per the Illumination specification. The main feeder upto the

distribution board shall be PVC insulated armoured cable. Wiring from distribution board to each

flood light fixture shall be by means of individual PVC insulated cables. All cables shall be neatly

clamped to the structure at intervals not exceeding 25cm.


25

ERECTION SPECIFICATION FOR LINE ON

TOWERS



VIP ROAD

KOLKATA - 700054

1 Survey

Detailed and Forest Survey of the route has already been carried out. Based on the tentative

Alignment Plan of the route attached with this bid document will be the guideline for carrying out

check survey. Detailed and Forest survey of a portion of the route may be felt necessary during

check survey, and that shall be conducted by the Contractor as per route alignment approved by

DVC.

1.1 Detailed survey

The object of carrying out detailed survey is to prepare longitudinal and cross section profiles on

the approved alignment to prepare the route plan showing details of deviation angles, important

objects coming within the right of way.

Work of detailed survey is distinctly done in two stages :

1. Actual field observations taking level readings and calculating distances, level differences,

deflection angles, offset distances etc.

2. Plotting of profiles on graphed tracing papers.

TOWER SPOTTING

The work of tower spotting is clearly divided into the following five operations :

1. Sag tension calculations.

2. Preparation of Sag Template.

3. Application of Sag Template to decide optimum tower position on Survey Chart.

4. Preparation of Structure Limitation Charts.

5. Deciding tower type and preparation of Tower Schedule.

SAG TEMPLATE

Sag Template drawing for AAAC (61/3.31mm) on DVC designed towers shall be prepared by the

Contractor and get approved from DVC. Inputs required for preparation of Sag Template will be

furnished by DVC to the Contractor. Based on the above drawing the Contractor has to prepare

Sag Template on rigid acrylic transparent plastic sheet and provide two sets of the same to the

owner for checking purposes. With the help of Sag Template and tower spotting data, tower

locations shall be marked on the profiles.

1.2 Check survey

Check survey is carried out for the following :


26

1. To reconfirm the work carried out during detailed survey.

2. To locate and peg mark the tower position on ground controlling to the route profiles.

3. To give direction pegs.

Check survey should be conducted to make rough check on detailed survey and to locate and peg

mark the tower position on ground conforming to the survey chart. Position of Tower shall be kept

on high places and good soil as far as practicable. Any deviation of the actual tower position from

the route profile drawing shall have to be corrected by the contractor accordingly in the drawing.

1.3 Forest survey

1) Identification & survey of forest area & Jungle Jhari area. A statement of Forest area and

Jungle-Jhari area to be prepared. Demarcation of forest boundary is to be done. Co-

ordination & interaction with Forest Authority and collection of Mouja map, necessary for

survey work will be done by DVC. Collection of Topo sheet is Contractor’s responsibility. The

contractor’s responsibility is to do the field survey work and align the route on Mouja map and

Topo sheet. All interaction and co-ordination with State Forest Department will be done by

DVC.

The tree-cutting shall be the responsibility of the owner except for that required during survey.

Contractor may please note that owner shall not pay any compensation for any loss or

damage to the properties or for tree cutting due to contractor’s work. However, the contractor

shall count, mark and put proper numbers with suitable quality of paint at his own cost on all

the trees that are to be cut by the owner at the time of actual execution of the work.

2) To evaluate and tabulate the trees and bushes coming within 17.5 meters on either side of

the centre line of alignment, the trees will be numbered and marked with quality paint serially

from angle point-1 onwards and the corresponding number will be painted on the stem of the

trees at height of 1 meter from ground level.

3) The contractor shall be responsible for tree enumeration for the purpose of initiating proposal

for obtaining forest clearance from Ministry of Environment and Forest. The contractor shall

submit 2 copies of the complete proposal to be moved for forest clearance to the satisfaction

of the Engineer-in-charge of the work.

1.4 Payments

Separate payment shall be made for survey which the contractor should quote separately for the

same as indicated in the price schedule.

2 Geo-Technical Investigation

2.1 General

The Transmission tower foundation shall be classified based on the soil conditions. Optimization of

foundation design and their safety mainly depend on correctness of soil and their analysis. The

scope of work includes detailed soil investigations at various locations such as railway crossings,

major road, crossing, power line crossings, river crossings and wherever soil strata differs.

However, the soil investigation activities shall be completed before the commencement of main

erection activities. Soil investigation may not be needed for all the locations of the line. The

required locations will be at the discretion of DVC.


27

2.2 Normal Locations

One bore hole of 150 mm dia shall be drilled at the centre point of the tower. Standard penetration

test (S.P.T) shall be carried out at 1.5 meter interval or change of strata upto the required depth of

2.5 times blow the depth of foundation below existing surface elevation or refusal whichever occurs

earlier. (By refusal it shall mean that a standard penetration below count ‘N’ of 100 is recorded for

30 cm penetration). Bore details and water table upto required depth below existing surface

elevation or refusal whichever occurs earlier shall be furnished in the report.

2.3 Special Locations

At certain locations such as river banks, river beds or midstream of river and at other places,

special soil investigation shall be carried out by drilling two holes each of 150 mm diameter at each

tower location on the diagonally opposite legs of the tower, considering the base width of tower as

20 meter.

Standard penetration tests shall be carried out at every 1.5 meter interval or change of strata till

refusal is met subject to maximum of 40 meter below the existing surface elevation.

Undisturbed samples of soils shall be collected at every 2.5 meter interval or change of strata

whichever occurs earlier.

In the hard rock the bore drilling shall be continued at least 5.0 meter to ascertain its sufficient

thickness.

2.4 Salient Test Requirements

The following covers the technical requirements for a detailed Geo-Technical Investigation &

submission of a detail geotechnical report :

1. Mobilization of all necessary equipment, men & materials to the project site for carrying out

geotechnical investigation and demobilization of the same after completion.

2. Sinking of 150 mm nominal diameter bore hole in all types of soil, sand including laterite, at

various locations up to a maximum depth of 20.0m– 25.0m below ground level or upto rock

level, whichever is earlier, using suitable approved method of boring including chiseling,

cleaning, providing casing pipe as required :

a) Performing SPT at every meter interval, at change of strata and at depths wherever

undisturbed soil samples could not be collected,

b) Collection of undisturbed soil samples at every meter and at change of strata,

c) Collection of disturbed soil samples and water samples,

d) Observation such as ground water table, rock level etc.

e) Transportation of collected samples to the laboratory,

f) Backfilling of bore holes with sand on completion.

Borehole to be properly stabilized with Bentonite.

Conducting laboratory test on soil samples including preparation of soil samples to determine the

following properties etc. as per specifications:


28

a) Bulk density & moisture content

b) Sieve analysis

c) Liquid limit and plastic limit

d) Triaxial shear test

e) Unconfined compressive strength.

2.5 Preparation of Test Reports

The geotechnical investigation report shall include but not be limited to the following:

i) Location & reduced levels of bore holes,

ii) A true cross section of all bore holes showing the classification & thickness of individual

stratum, position of G.W.T., rock stratum if met with etc.,

iii) Water level & rock level contours,

iv) Plot of SPT ‘N’ values (both corrected & uncorrected) with depth,

v) Results of all tests in tabular as well as graphical forms,

vi) Values of cohesion, angle of internal friction, skin friction.

vii) High flood level of the area.

The report should contain specific recommendation for the type of foundation. In case the soil

parameters obtained from the soil investigation report for a particular tower location, differ from the

ones considered during design, a fresh design has to be developed for such locations.

2.6 Recommendations

Recommendation shall include but not be limited to the following:

a) Type of foundation to be adopted for Transmission Towers duly considering the sub-strata

characteristics, G.W.T.

b) For shallow foundation the following shall be furnished :

Net safe bearing capacity for isolated square footing of size 4.0 m & 5.0 m at different

founding depths of 3.0m, 4.0m & 5.0m below G.L. considering shear & differential settlement

criteria

c) If piling is envisaged the following shall be furnished with comprehensive supporting

calculations :

i) Type of pile & reasons for recommendation.

ii) Suitable founding strata for the pile.

iii) Estimated length of 600/800 dia pile considering end bearing and frictional resistances.

iv) Safe lateral & tensile load carrying capacity of pile.

v) Magnitude of negative skin friction considering Scour Depth.

All work shall be carried out as per relevant I.S. code & standards etc.

3 Earthwork in Excavation

3.1 General

Each tower shall have four footings; the excavation of the pits for the four footings shall be of same


29

type unless otherwise approved by the Engineer. The four pits shall be marked by the contractor at

his cost as such the tower is open in the direction of the line or the line bisecting the angle of

deviation for angle location.

The levels up and down of each pit centre with respect to the centre of the tower location shall be

noted by the contractor & approved by the Engineer or his authorised representatives before the

excavation is started. The surfaces of the excavated pits shall be made full dimensions required

and as per drawings.

All the excavated materials shall be dumped away from the pits at a distance not exceeding 50

meters preferably in diagonal directions keeping the space along the centre line free for foundation

work. Care shall be taken that no moving vehicles or heavy equipments are drawn too near the

foundation excavation.

3.2 Classification of Soil

The classification of various types of soil will be as under:

Ordinary soil : The ordinary soil will mean all types of soil excluding all kind of rocks and wet

soil.

Hard soil : Hard soil will mean soil mixed with moorum, kankor etc. but not soft rock.

Slushy soil : Slushy soil will mean the soil below water level.

Soft rock : This will mean decomposed rock, hard gravel, kankor, lime-stone, laterite or any

other soil which cannot be easily excavated with pick axe or spade.

Hard rock : Hard rock will be that which requires chiseling or drilling and blasting. The

cost of drilling and blasting are to be included in the quoted rate. The contractor

shall supply requisite blasting material and be responsible for the purpose of the

storage and use of the material. Blasting shall be done so that pits are as near to

the designed dimension as practicable.

Fully/Partially : Fully/Partially submerged soil means locations where water is met within 1.5

submerged soil meter 0.75 meter from ground respectively. It should be avoided as far as

possible.

Filled up soil : It should be avoided.

Sandy soil : Soil mixed with Sand (or fully Sandy location).

The contractor will be required to submit at his own cost to the Engineer his report about the

water-logging, if any, sub soil water-table and type of soil encountered at the locations along with

his proposal for type of foundation. He should also be satisfied that the allowable bearing

pressure of the soil as mentioned in the drawing will be available at the locations. The approval of

the Engineer should be obtained regarding type of foundation to be used.

3.3 Classification of Foundation

Classification of soil shall be made according to I.S. 200 (Part-I) for footing cast in open pits .

Depending upon the ground water table and type of soil / rock and presence of surface water the

foundations can be classified as follows :

a) Normal Dry Soil Foundations

When water table is below foundation level and when soil is normal, dry, cohesive and

homogeneous upto the full depth having clay content of 10-15%.


30

b) Wet Soil Foundations

When water table is above foundation level and up to 1.5 meter below ground level. The

foundations in the soils which have standing surface water for a long period with water

penetration not exceeding 1.5 meter below ground level (e.g. paddy fields) are also classified as

wet foundations.

c) Partially Submerged Foundations

When water table is at a depth between 1.5 meter and 0.75 meter below ground level and when

the soil is normal and cohesive.

d) Fully Submerged Foundations

When water table is within 0.75 meter below ground level and the soil is normal and cohesive.

e) Black Cotton Soil Foundations

When the soil is cohesive having inorganic clay exceeding 15% and shrinks when dry, swells

when wet, (need not be always black in colour) resulting in differential movement extending upto

a depth of about 3.5 meter below ground level.

f) Soft Rock/Fissured Rock Foundations

When decomposed or fissured rock, hard gravel or any other soil of similar nature is met which

can be executed without blasting. Under cut & Rock Anchor type foundation can be used at

these locations.

In case of fissured rock locations where water table is met at 1.5 meter or more below ground

level, submerged fissured rock foundation shall be adopted. When the water table in such

location is met within 1.5 meter from ground level, fully submerged fissured rock type foundations

shall be adopted.

g) Hard Rock Foundations

Where chiseling, drilling and blasting is required for excavation hard rock type foundation are to

be used. Rock anchoring is to be provided to resist uplift forces.

The above categorizations has been done for economizing the foundations, as uplift resistance

of foundation is a critical design factor which is greatly affected by the location of water table and

the soil surrounding the foundation.

In addition to the above, depending on the site conditions other types of foundations may also be

developed for :

1. Intermediate conditions under the above classifications to effect more economy

or

2. For locations where special foundations (well type or piles) are necessitated.

While classifying foundations of Wet, Partially submerged, Fully submerged foundations

mentioned above, the worst conditions should be considered and not necessarily the conditions

prevailing at the time of inspection. For instance, there are area where sub-soil water rises when

canal water let-out in the fields raising sub-soil water to a considerable degree. Similarly, the

effect of monsoon or when the nearby reservoirs are full should also be considered and not the

conditions prevailing in open season or summer when work is carried out normally.

3.4 Dewatering

Dewatering, if required, shall be done at the cost of the contractor either manually or by


31

mechanical pumps or power driven pumps to facilitate excavation and during excavation. The

pumps shall be suitable for handling mud water. The pits shall also be kept water free during

concreting and till 24 hours of concreting the foundation. No backfilling should be done till pits

are dewatered fully.

3.5 Shoring and Strutting

Shoring and strutting shall be used in pits excavated in sandy soil or in water bearing strata if

directed by the Engineer, where there is every likelihood of pit collapsing. Shoring and strutting

shall be made out of timber planks or steel frame and struts of adequate strength to suit the

requirement as directed by the Engineer-in-Charge. Separate unit price per square meter shall

be quoted for this item. Shoring and strutting may be necessary during excavation or during

concreting or during excavation and concreting both. However, payment for shoring and strutting

will be made once and not for the second time even if shoring and strutting are required to be

provided during excavation and concreting both.

3.6 Measurement

The payment for excavation of pits will be made on the basis of pre-work ground level and post

work ground level measurement of the tower pits. No payment will be made for the excavation

made in excess to the quantity of excavation shown in the approved drawings. In case it is

required to excavate more than what is mentioned in such drawings, then approval of the

Engineer should be obtained specifically for such cases and in that case, payment will be made

for the total excavated quantity certified by the Engineer as per rate quoted by the contractor.

If the different types of soil are encountered within a pit while excavating, then payment will be

made as per volume measured for different types soil therein. No payment for dewatering will be

made for any type of soil. The rate of excavation for different types of soil should include the cost

of dewatering, if required and also the cost of pit-marking.

Before starting the excavation of pits, the contractor or his representative should inform the

Engineer or his representatives. The contractor or his representative should also inform the

Engineer or his representative after the excavation is completed but before backfilling to enable

the Engineer to take measurement of the quantity of earth excavated and type of soil

encountered.

In case of the excavated pits being ready for backfilling after stub setting where contractor has

filed a statement protesting the measurement taken regarding the quantity and nature of

earthwork excavated for which payment is to be made, the contractor shall delay back-filling

work until the Engineer-in-Charge is able to verify the necessary measurement or to secure

such an additional data as may be necessary for the proper consideration to the contractor’s

protest, which shall be done by the Engineer-in-Charge of the work within 10 days from the date

of receipt of such protest. Such delay shall be considered incidental to the work and no additional

compensation will be granted to the contractor thereof. Failure of the contractor to permit such

re-examination before back-filling shall be considered as waiver of all claims.

3.7 Payment

Payment for excavation for tower foundation shall be made for unit price per cubic meter. If,

during the progress of excavation or after excavation is completed, it is found necessary or

desirable to change the type of footings or to change the dimension of excavation for the footings

from those shown in the drawings or prescribed by the Engineer, payment for such change or

allocation of cost thereof shall be as follows :


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i) Where the change in the type of footing or change in the dimension of the excavation for a

footing are the result of the faults on the part of contractor e.g. defects in pit marking,

improper excavation method or means of supporting excavation or of taking inadequate

means of protection of the excavation from weathering or of the contractor’s delaying

between the excavation of footings and placing of concrete etc., the cost of all additional

excavation, reinforcement, cement concreting and back-filling shall be borne by the

contractor.

ii) Where the type of footing or excavation is changed for no fault of the contractor, but it is felt

so necessary by DVC and done accordingly, payment for excavation, back-filling etc. so

performed shall be made by DVC at the unit price for the items. No additional rate above the

unit price for the work shall be allowed to the contractor.

4 Earthwork and Backfilling

The backfilling of the excavation pits shall be carried out after the concrete work is over, form

work is opened, shoring and strutting, if any, are removed. The backfilling shall be done by the

contractor only after the receipt of approval from the Engineer or his representative. Unless

special instruction given in any specific case, no backfilling work shall be carried out if the repair

& finishing work is not complete. Finishing of coping (the top of the foundation above ground)

may be done after the completion of backfilling. Backfilling shall be done with excavated soil if

the excavated soil is free from decomposed soft rock and gravels not more than 50 mm and also

free from organic and other foreign materials. In case the excavated soil is not of such

specifications backfilling should be done with normal soil from suitable borrow pits.

The backfill should be compacted with special care. Good thorough compaction is to be made for

ensuring uplift resistance and development of passive earth resistance. The backfill should be

deposited in layers of thickness of not more than 200mm after compaction. The back filling

operation should be such that the materials when compacted will be blended sufficiently to

secure the best practicable degree of compaction. The backfilling is to be carried out to an

elevation up to concrete level and with a size equal to maximum plan dimensions of excavated

pits at ground level. Volume of backfilling shall be considered equal to that of excavation to

account for the extra backfilling above ground level. The backfill material shall have optimum

practicable moisture content requiring for the purpose of compaction and curing as determined

by the Engineer and the moisture content shall be uniform throughout the layers. The moisturing

shall be made by sprinkling of water at the site of compaction. The backfill shall be compacted by

tamping or by such means or equipments as approved by the Engineer. Care shall be taken that

backfilling is started from inner end of the pits, towards the outer end.

The stub template may be struck and removed only after getting clearance from Engineer or his

representatives.

The backfilling of foundation shall be carried out so that after one / two monsoon the level of

backfilled earth does not go below the surrounding ground level.

On completion of the backfilling as per above requirements and completion of curing period,

proper grading should be carried out to drain out the water.

Separate rate shall be quoted by the contractor for backfilling work (I) with soil obtained from

excavation of foundation and (II) with soil from borrow pits. In case of backfilling being done with

normal soil from borrow pits no separate payment for excavation of such soil from borrow pits

including its carriage to the place of backfilling will be paid.


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5 Sub-Base

A lean concrete sub-base shall be provided if required and directed by the Engineer-in-Charge.

The work should be done as per instruction of the Engineer-in-Charge. Payment for supplying

and placing lean concrete sub-base will be made at unit price per cubic meter.

6 Stub Setting

6.1 Setting of Stub with Template

The Stubs are set with the help of the Stub-setting Templates, which are supplied loose, ready to

be assembled at site. All four excavated pits are to be lean concreted to correct level sighted

through level and the stubs are to be placed on the lean concrete pad. Correct alignment is

carried out by 0.9 Kg. Plumb bob 4 in numbers hung from centre of horizontal bracings.

Following is the procedure for Stub-setting at Site :

1. Assemble the Template as per the drawing along with the supply.

2. Set the Template as per the drawing at site.

3. Place the Stub-setting Jacks below the Template.

4. Align Template, along with the line and centre it over the centre peg of the location.

5. Fix up the stub to the Template and with the help of a dumpy level, level the Template

corners to the required level.

6. Ensure that all the four stubs are at the same level.

7. Check the alignment and centering of the Template again.

8. By placing on 8 to `12 screw jacks according to the length of Template, with a leveling

instrument fine adjustment can be made by lifting / lowering the screw jacks, and the stubs

can be perfectly leveled. This ensures accurate verticality of the tower. For ensuring all

towers in one line and cross-arms at right angle to it, 4 plumb bobs should be dropped from

the centre of the horizontal members of the Template to correspond to the cross pegs and

alignment pegs given during the line alignment survey for the tower location.

The contractor shall be fully responsible for correct setting of stub in accordance with the drawing

supplied, at the exact locations and alignments and precisely at correct level. The stubs are to be

set with the help of stub setting templates supplied by DVC & the contractor wherever necessary.

6.2 Setting of Stub with Section Method

There may be occasions when templates may not be available from DVC.In such special and

exceptional cases DVC may permit setting of the stubs by first section method i.e. lowest section

of the tower body complete with bracings may be used as template.

6.3 Payments

When stubs are set by using first section methods the contractor shall be entitled to no additional

payment over the unit price bid for setting of stub. Payment for erection of first section with

bracings, excluding weight of stubs, will be made at the unit rate quoted for tower erection and

will be included in the item “Erection of tower.” However, if the contractor quote separate rate for

setting of stubs by using first section method, the same will be paid accordingly.


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7 Concrete

7.1 General

All reinforced concrete will be either with M-15, M-20 or M-25 concrete. Nominal Mix proportion

1:2:4, 1:1.5:3 & 1:1:2 by volume shall be taken as equivalent to M-15, M-20 and M-25

respectively. Characteristic compressive strength of 15 cm cube at 28 days for M-15, M-20 and

M-25 mix is 15 N / Sq.mm , 20 N / Sq.mm and 25 N / Sq.mm respectively.

All concrete work shall fully comply with the latest edition of Indian Standard Specification IS :

456, "Code of Practice for Plain and Reinforced Concrete".

Cement, sand and stone chips (Coarse aggregate) shall be used for concreting with 20 mm and

down stone chips for chimney and pyramid portion.

Approved mechanical vibration for all structural and reinforced concrete shall be mandatory.

Immersion type vibrators (65 mm and / or 75 mm dia and 500 mm to 600 mm long) with a

minimum vibration of 8000 revolutions / minute shall be used. Use of pneumatic and / or

electrical vibrators are mandatory.

Sample of cement, stone chips and sand to be used for construction works by the contractor

must got approved by the Engineer before use. Cement, Stone chips and sand are to be

supplied by the contractor at his own cost.

Specification for the materials are given below .

7.2 Materials

a) Cement :

Cement shall be ordinary cement conforming to IS : 269 / IS : 455. Cement shall be kept in clean

dry, moisture-proof covered stores. It shall be adequately protected from condensation, rising

damp and atmospheric moisture. Sufficient cement shall be stored at all times to ensure

continuity of work. Not more than ten bags shall be stacked in any tier. The Engineer-in-charge if

consider any cement defective, then irrespective of its origin and / or manufacturer’s test

certificates, such cement shall be tested immediately at DVC’s laboratory or any Laboratory

approved by DVC, and until the results of such tests are found satisfactory it shall not be used in

any work. The Contractor shall not be entitled to any claim of any nature on this account.

The cement supplied by contractor should be purchased directly from the approved manufacturer

and should be supported by matching challans of the manufacturer.

b) Fine Aggregates :

Fine aggregates (Sand) shall be clean, sharp coarse, gritty to the touch and free from elongated

and flaky particles with a fineness modulus between 2.8 and 3.2 and shall pass through sieve no.

16. It shall be clear and free from any mixture of clay, dust, vegetable matter, mica, shale, loam,

salts and organic matter, or other impurities, which may be considered by the Engineer-in-

Charge as harmful. Sand containing clay shall be thoroughly washed by the contractor at his own

expenses before use.

Unless otherwise specified fine sand may be used for sand filling and for mixing with cement for

mortar and plaster.

c) Coarse Aggregates :

Coarse aggregates, whether crushed stone or washed and graded gravel shall conform to sieve


35

analysis presented in Table-II of IS:383 and when tested shall conform to IS : 2386 ( Pt. I to VIII)

Stone aggregates (20 mm. & down) shall consist of good, hard and broken stone of the gauge

specified and approximately cubicle in shape. It shall be free from dirt, clay, heaves or any

organic matter of admixture of soft or decayed stone. Different sizes shall be stacked sufficiently

apart or separated with approved wooden bulk heads. The Engineer-in-Charge if consider any

aggregate defective or of poor quality, then irrespective of any previous approval or tests,

samples of such materials shall be immediately tested and until the result of such tests prove the

materials to be satisfactory, it shall not be used in any work. The contractor shall not be entitled

to any claim of any nature on this account.

d) Water :

Water shall be clean, transparent, tasteless and free from organic or deleterious matter in

solution or suspension in quantities which may impair the strength or durability of the concrete.

Contractor shall provide his own arrangements and at his own cost for distribution, store, filtration

and / or treatment, as necessary of the required quantity of water. The water should be

reasonably clear and of turbidity limit 2000 ppm.

e) Reinforcement :

All reinforcement shall be of tested quality strictly in conformity with the relevant Indian

Standards. Steel reinforcement shall comply with the requirement of the latest edition of IS-1786.

All reinforcement shall be HYSD bars of Grade Fe-415. The Engineer-in-charge shall check and

ensure that appropriate test certificates of materials are available to his satisfaction. If demanded

by DVC the contractor shall submit the manufacturer’s test certificate for steel. Otherwise,

necessary tests shall be made by the Contractor at his own cost to ensure that the quality and

physical properties of the materials used conform to the specification. No complaints or claims

shall be entertained on this account.

All reinforcement materials, before its final use, shall be free from loose mill scales, loose rust,

oily or bituminous coating or injurious adherents. Pitted and otherwise defective rods shall not be

used. The binding wire (18 SWG) shall be included in the cost of reinforcement rod binding and

shall be borne by the contractor.

All bars shall be rigidly held in position before concreting as per requirements of the latest edition

of IS:2502. No welding of rod shall be allowed. Laying of Reinforcement bars shall be in

accordance with relevant I. S. specifications unless otherwise specified. Lap lengths shall not be

less than the minimum values specified in the relevant codes of practice. The laps shall be

staggered. Dowel bars shall be provided wherever required or as directed by the Engineer or as

shown in the approved drawings.

The Contractor shall check, ensure and procure in time, as necessary, the reinforcement

materials required for the continuous scheduled progress of the work till completion.

All reinforcement steel shall be suitably stacked and stored by the Contractor to protect it from

damage by corrosion, and to prevent distortion of section in long lengths.

The horizontal distance between parallel reinforcement bars in row shall not be less than the

greatest of the following :

a) The larger diameter if the diameter be unequal.

b) Diameter, if the diameters are equal.


36

c) 6 mm. more than the nominal maximum size of coarse aggregate.

The vertical distance between two rows of reinforcement bars shall be not less than 12 mm

unless they are cross reinforced or lapped. No reinforcement shall be bent when in position in

the work without approval whether or not this is partially embedded in concrete. Reinforcement

shall be accurately fixed and maintained in position by approved means. Placing of

reinforcement shall be completed well in advance of concreting. In case reinforcement bars are

in coil form, straightening of the same shall be done by the contractor at his own cost.

7.3 Maintenance of Log Book for Concreting Work

While all efforts shall have to be made by the contractor to achieve rapid progress in construction

in all sector and to avoid deterioration in the quality of concrete work, it is necessary that for

every tower a log book should be maintained showing –

a) The date and time of commencement of pouring of concrete.

b) The date and time of completion of pouring of concrete.

c) The quantity of cement used in concreting foundation.

The log book shall have to be signed by both the representative of the contractor and DVC.

7.4 Consistency

The amount of water used in concrete shall be regulated as required to secure concrete of

proper consistency and to adjust for any variation in the moisture content of grading of the sand

and aggregates as they enter the mixture. Addition of water to compensate stiffening of the

concrete before placing will not be permitted. Uniformity in concrete consistency from batch to

batch will be required. The slump of concrete after deposition but before it has been consolidated

shall not exceed 76.2 mm. DVC reserves the right to require a lesser slump whenever concrete

of such lesser slumps are required. DVC also reserves the right to make the slump test in

accordance with the latest practice. The concrete mix has to be used within half an hour of the

mixing.

The proportions of nominal mix concrete & amount of water may be estimated in accordance

with Table-4, Table-5 & Table-9 of IS : 456.

7.5 Batching

The contractor shall provide equipment and shall maintain and operate the equipment as

required to accurately determine and control the amount of each separate ingredient entering

the concrete. The amount of cement, sand, stone chips and water entering each batch of

concrete shall be determined by the volumetric measurement.

7.6 Mixing

The concrete ingredients shall be mixed in a batch in right proportions in mixing drum & shall be

kept rotating for not less than two minutes after all the ingredients except full amount of water are

in the mixer. The Engineer reserves the right to increase mixing time when charging and mixing

operation fails to produce a concrete batch whose consistency is not uniform. The concrete as

discharged from the mixture shall be uniform in composition except where changes in

composition or consistency are required. Excessive over mixing requiring addition of water to

preserve the required concrete consistency will not be permitted. Any mixer when produce

unsatisfactory results shall be repaired promptly and effectively for controlling the mixing time.

Hand mixing as per standard practice will be allowed only when concrete mixer fails during


37

concreting. Hand mixing may also be allowed at the discretion of DVC’s representative in-charge

of the work as also for the location where mixer machine is not accessible.

When hand mixing is adopted it shall be carried out on a water tight platform such as 1.8 mm

galvanised iron plain sheets properly overlapped and placed upon level ground. The coarse

aggregates shall be spread out first evenly over the sheets. The fine aggregate shall be evenly

spread out over the coarse aggregate. The aggregates shall then thoroughly be mixed together

and leveled. The required amount of cement shall now be spread evenly over the mixed

aggregates and wet mixing shall start from one end with required amount of water using shovels.

The whole lot shall not be wetted, instead, mixing shall proceed progressively. The whole

operation shall not be taken more than 15 minutes. If moist sand is used allowance for bulking

shall be made.

In case of such hand mixing being permitted, 10% extra cement on this account will be added at

Contractors expense.

For mixing in mechanical mixers, the same order of placing ingredient in the loader/drum shall be

adopted, that is coarse aggregates shall be put in first followed by sand, cement & water.

7.7 Forms (Form boxes or Muff box) :

Form boxes made of steel will be used to confine the concrete and shape it to the required line.

The inner side of the forms shall be cleaned and oiled before concreting (quality of oil to be

approved by Engineer or his representatives). Immediately before the concrete is placed,

precaution shall be taken so that forms are in proper alignment and tight to prevent any loss of

mortar and forming of honey combing in the concrete and also its supports are thoroughly

secured and tight.

Steel Form Boxes which will be supplied to the contractor have to be returned in good condition

to DVC stores on completion of work, failing which cost of form boxes (muff boxes) will be

recovered by DVC from the contractor at the rate decided by DVC, which in no case will be less

than the rates paid to the contractor for supply of this item. Steel form-boxes (muff-boxes) shall

not be galvanized, instead they will be painted with 2(two) coats of red-oxide primer paint.

7.8 Placing/Depositing the Concrete

The contractor shall keep the Engineer or his representatives intimated at least 7 (seven) days in

advance as to when placing of concrete will be performed. The contractor should try to follow his

programming in this regard. Incase of abnormal situation or emergency condition, intimation shall

be given to the Engineer or his representative at least 24 hours before the starting of the work.

Unless inspection is waived out in any specific case, placing of concrete shall be performed only

presence of Engineer or his authorized representative. Contractor will arrange for transport for

the Engineer for inspection, if Engineer so desires.

The concrete must be used while fresh and shall be laid ( not thrown ) in layers not exceeding

150 mm and consolidated well. The concrete shall be placed and compacted before setting

commences and should not be subsequently disturbed. The placing should be such that no

segregation takes place. Concrete shall be thoroughly compacted during the placing operation

and thoroughly worked around reinforcements, embedded fixtures and into corners of form work

by means of 16 mm dia poking bars pointed at the ends so that no honey-combing is left in the

concrete. After concreting the chimney portion to the required height, the top surface should be

finished smooth, with slight slope towards the outer edge to drain off the rain water falling on the


38

coping. Concreting shall be done continuously so that their subsequent layers are laid before the

initial setting of the bottom layer begins. The time from starting of mixing to ramming in final

position shall not take more than 30 minutes.

If fresh concrete is to be laid on the old concrete which is less that 10 days old, the surface of old

concrete should be cleaned with wire brush and washed with a layer of thick cement slurry

before new concrete is laid. But if the concrete is 10 days or more old, then the top of the set

concrete should be chipped and cleaned thoroughly with wire brush and fresh water, and layer of

12 mm thick cement mortar (1:2) shall be laid evenly after giving a coat of cement slurry as

specified above to ensure proper bonding between old and new concrete, for which no extra

payment over the unit price for reinforced cement concrete work will be made.

7.9 Curing

The concrete after setting for 24 hours shall be cured by keeping the concrete wet continuously

for a period of 14 days after laying. The pit may be back filled with selected earth sprinkled with

necessary amount of water and well consolidated in layers not exceeding 200mm after a

minimum period of 24 hours and thereafter both the back filled earth and exposed chimney top

shall be kept wet for the remainder of the prescribed time of 14 days. The uncovered concrete

chimney above the back filled earth shall be kept wet by providing empty cement bags dipped in

water fully wrapped around the concrete chimney for curing and ensuring that the bags be kept

wet by frequent pouring of water on them.

No separate payment shall be made for curing. The rate for concrete should include the curing

charges.

7.10 Removing of Form Work

All form work shall be removed without such shock or vibration as would damage the concrete or

forms.

Under fair weather conditions (generally where average daily temperature is 25°C or above) and

where ordinary cement is used, forms may be struck after 24 hours of the placing of concrete. In

dull weather (such as rainy periods) and very cold temperature, the forms shall be struck after 48

hours of the placing of concrete. The consequences arising during the removal of the shuttering

shall be contractors entire responsibilities. Before reuse all forms shall be thoroughly cleaned as

specified earlier & may be used after repair, if any, with the approval of the Engineer.

7.11 Finishing of Concrete

If after the form work has been struck, the concrete surfaces are found to have defects, all the

damaged surface shall be repaired with mortar application composed of cement and sand in the

same proportion as the cement and sand in the concrete mix. Such repairs shall be carried out

within 24 hours after removal of forms and before the foundation pits are backfilled. The form

work is to be struck and repairing if required is to be done in presence of the Engineer or his

representative.

The cost of materials, labour and equipment, required in the repair of concrete shall be borne by

the contractor.

In case of salty / saltish soil, special type of bituminous paint shall be applied over the finished

concrete surface. The paint shall be supplied by DVC, but no payment for painting will be made

by DVC.

Exposed surface of the chimney portion of the foundation above the ground level shall be


39

brought to uniform surface by plastering. Finishing shall be neatly done with cement punning.

The top surface of the foundation shall be sloped towards the outer edge to provide drainage

from the steel stub angle. 12 mm thick cement mortar in 1:6 ratio shall be used.

7.12 Payment

Unit rate per cubic meter of reinforced cement concrete work including plastering and neat

cement punning of the exposed surface of chimney portion should be quoted.

In case of any special type of foundation and modification in the foundation design resulting in

excess quantity of concrete, contractor will be paid as per quoted rate. No extra rate on this

account will be entertained. However, if extra quantity of work is involved, then it will be paid as

per original rate quoted by the contractor in the tender.

7.13 Inspection of Concreting Work

The Engineer-in-charge reserves the right to uncover and examine any foundation and if any

foundation is found defective, the contractor shall be required to rectify or do new foundation, if

required; at his own cost and put all these back in order.

7.14 Tolerances

The tolerances for various items connected to the foundation works of transmission line are as

under.

A) Stub-setting (Tower Footing)

All the stub angles for tower legs shall be set accurately to the grade and alignment shown on

the drawings. The difference in elevation between identical parts of any two stub angles shall

not exceed 1/1000 of the horizontal distance between the stubs, allowance being made for

difference, if any, in the lengths of legs and extensions. The actual elevation of any stub angle

shall not differ from the computed elevation by more than 1/100 of foundation depth. Stub angles

shall be located horizontally so that each is within 6mm of its correct position, or by the amount

of play as offered by the clearance between bolts and holes of the stub-setting template. To

ensure greater accuracy, the hole clearance shall not be greater than 1.5mm on the punched

side of the Template members.

The following tolerances shall be applicable in case of position of foundations erected with

reference to the tower position spotted on Survey Charts :

Type of Tower

Out of Alignment

From Centre Line of Route

From Transverse Centre line

Suspension 0.5 degree 25 mm +/-250 mm

Tension 0.5 degree 25 mm +/-25 mm

(Set at bi-section of deviation angle)

B) Concrete and Form Dimension :

The maximum tolerance on the dimensions shall be +/-10 mm. All tolerances shall not be on the

negative side.


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8 Miscellaneous

8.1 Encasing of Stub

Encasing upto top of stub by mass concrete after erection of tower may be required to be done if

desired by the Engineer. For that rate mentioned in the schedule for mass concrete shall be

applied.

8.2 Embankment

The contractor shall construct embankment for towers at the locations where embankment is to

be made as directed by Engineer-in-Charge. The contractor should quote different rates for

stone pitching, random stone masonry and brick masonry pitching.

9 Erection of Tower

9.1 General

The towers shall be erected on the foundations not less than 14 days after concreting or till such

time that the concrete has acquired sufficient strength. The towers are erected as per the

Structural / erection drawings furnished by DVC to facilitate erection. For the convenience of

assembling the tower parts during erection operations, each member is marked in the

factory to correspond with a number shown in the erection drawing. Any damage to the steel

and injuring of galvanizing shall be avoided. No member shall be subjected to any undue

overstress, during erection.

Towers may be erected either by Built-up method or by Section method.

Built-up Method

This method consists of erecting the towers, member by member. The tower members are kept

on ground serially according to erection sequence to avoid search or time loss. The erection

progress from bottom upwards. The four main corner leg members of the first section of the

tower are first erected and guyed off. The advantages of the built-up method are as follows:

a) Tower materials can be supplied to site in knocked down condition which facilitates easier

and cheaper transportation.

b) It does not require any heavy machinery such as cranes etc.

c) Tower erection activity can be done in any kind of terrain and mostly throughout the year.

d) Availability of workmen at cheap rates.

Section Method

In the section method, major sections of the tower are assembled on the ground and the same

are erected as units. Either a mobile crane or a gin pole is used. The gin pole used is

approximately 10 m long and is held in place by means of guys by the side of the tower to be

erected. The two opposite sides of the tower section of the tower are assembled on the ground.

Each assembled side is then lifted clear of the ground with the gin or derrick and is lowered into

position on bolts to stubs or anchor bolts. One side is held in place with props while the other

side is being erected. The two opposite sides are then laced together with cross members and

diagonals; and the assembled section is lined up, made square to the line. After completing the

first section, gin pole is set on the top of the first section. The gin rests on a strut of the tower

immediately below section. The gin rests on a strut of the tower immediately below the leg joint.

The gin pole then has to be properly guyed into position.


41

The first face of the second section is raised. To raise the second face of this section it is

necessary to slide the foot of the gin on the strut of the opposite of the tower. After the two

opposite faces are raised, the lacing on the other two sides is bolted up. The last lift raises the

top of the towers. After the tower top is placed and all side lacings have been bolted up all the

guyes are thrown off except one which is used to lower the gin pole. Sometimes whole on face

of the tower is assembled on the ground, hoisted and supported in position. The opposite face is

similarly assembled and hoisted and then the bracing angles connecting these two faces are

lifted.

9.2 Tightening of Nuts, Punching of Threads and Tack Welding of Nuts

All nuts shall be tightened properly using correct size spanners. Before tightening it is ensured

that filler washers and plates are placed in relevant gaps between members, bolts of proper size

and length are inserted and one spring washer is inserted under each nut. In case of step bolts,

spring washer shall be placed under the outer nut. The tightening shall be carried on

progressively from the top downwards, care being taken that all bolts at every level are tightened

simultaneously. It may be better to employ four persons, each covering one leg and the face to

his right.

The threads of bolts shall be projected outside the nuts by one to two threads and shall be

punched at three positions on the top inner periphery of the nut and bolt to ensure that the nuts

are not loosened in course of time. If during tightening a nut is found to be slipping or running

over the bolt threads, the bolt together with the nut shall be changed outright. The nuts upto

Bottom Cross arm level shall be punched and tack-welded.

9.3 Painting of Joints

For galvanized towers in coastal or highly polluted areas, the joints shall be painted with zinc

paints on all contact surfaces during the course of erection.

9.4 Checking of Verticality of Erected Towers

The finally erected tower shall be truly vertical after erection and no straining is permitted to bring

in is alignment. Tolerance limit for vertical shall be 1 in 360 of the tower height.

9.5 Payments

Payment for the erection of tower shall be made by DVC on the per Metric Ton basis. The rate

quoted by the tenders for erection of tower shall include all works involved in the tower erection

as per tower drawing, including transporting, storing and carriage of all materials to site from

contractor’s stores and checking and punching and tack welding of bolts on the towers complete

in all respect. For erection of the extension pieces of special towers, whenever necessary,

payment will be made on Metric ton basis as per rate quoted for erection of towers and no

additional rate over the unit price bid for erection of tower will be allowed for the above purpose.

Measurement for payment of erecting the various types of steel towers will be made on the basis

of weights computed by DVC and calculated in accordance with the bill of materials with variation

sheets, if any. Final payments shall become due only after complete erection of tower and proper

punching and tack welding.

10 Grounding of Towers

At all locations the tower shall have to be grounded to bring down the lower footing resistance to

10 ohm and below. Measurement of the tower footing resistance as per directive of the engineer

has to be done by the contractor at his own cost. Such measurement has to be done in dry


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weather in presence of the engineer or his representative before the stringing of earth wire. The

two stubs which are in diagonally opposite direction are to be earthed. The earthing shall be

done by G.I. Pipe connected with stub through GI flats and as per drawing supplied by the

purchaser and as per instruction of the Engineer. One set of pipe earthing consists of 2 nos. GI

pipe and GI flats. Where grounding of tower by GI pipe is not possible or the desired level of

tower footing resistance not obtained the counter-poise earthing at the discretion of the site

engineer should be done. The counterpoise earthing shall consist of four numbers 45 x 6 mm

galvanised iron strip 30 M in length connected at four legs and buried radially at least at 600 mm

depth below ground. In case counter poise earthing is required for 2 legs only that will be

considered as one set. Similarly grounding of tower at one leg for pipe type earthing shall be

treated as ½ (Half) set.

The contractor should submit statement mentioning the date of measurement of tower footing

resistance and tower footing resistance value and details of grounding adopted for each location.

10.1 Payments

Payments for grounding including excavation or backfilling of tower shall be made on per set

basis. One set shall mean complete grounding of one tower at two legs for pipe type earthing

and counterpoise earthing.

If more than one set of grounding is required for any tower, then payment for the additional set

will be made at the rate quoted by the contractor. Pipe type earthing and counterpoise earthing

shall be done as per IS-3043and IS-5613 (Part-II/Sec-2).

11 Insulator hoisting and Power and Earth Conductor Erection including fixing of Tower accessories

Work involves :

1) Hoisting of insulators and fixing on the towers and erection of hardware sets.

2) Jointing of conductors.

3) Running out (also called paying out) and stringing (pulling up) of conductor.

4) Tensioning, sagging as per approved sag-tension (stringing) chart and clipping in of the

conductors (pulling up to proper tension, transferring of conductor to insulators).

5) Fixing of vibration dampers preformed armour rod and other tower accessories. Viz. Number

plate, Danger notice plate, Phase plate, Circuit plate, Bird Guard, Anticlimbing devices and

step bolts etc.

6) Erection of jumpers at the section and angle towers and hoisting and fixing of suspension

insulator strings to restrict jumper swing.

The contractor shall be entirely responsible for any damage to tower, conductor or its

accessories during wiring of lines. He shall also be responsible for proper distribution of the

conductor drums to keep the number and lengths of cut pieces of conductor to a minimum. Cut

pieces as well as empty drums of conductor and earthwire shall be taken away by the contractor

as per SCC. The following further precautions shall be observed.

a) There shall be not be any joint in conductor in Railway crossing, main road crossing, power

line crossing and river crossing.

b) No joints shall be less than 30 M away from adjacent towers.


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c) There shall not be fore than one joint in a span on each conductor.

d) Requisite and adequate precautionary measures are to be taken while stringing & sagging

power line, road, across Railway & other important crossing.

Rate of stringing & sagging of power conductor & earth wire quoted against specific item of

erection schedule of works should cover crossing of the power line, Railway line, small river,

road etc. if any falling along the transmission line. For big river crossing separate rate for string

the span between Anchor tower to Anchor tower as indicated may be quoted.

Requisite and adequate precautionary measures shall be taken while stringing and

sagging over power line, road, Railway and other important crossing.

11.1 Hoisting of Insulators and fixing on the Towers and Erection of Hardware Sets

The insulator string shall include shackles, yokes, clevises, dead end fittings, strain and

suspension clamps etc. associated with fittings, except where otherwise specified. Single

suspension insulator set of 14 disc shall be used in tangent location, single strain insulator set of

15 disc shall be used in angle location. For main road crossing, power line crossing etc. double

insulator set of 2 x 14 disc (suspension) at tangent location and 2 x 15 disc (strain) at angle

location shall be used. For Railway crossing 2 x 15 disc for suspension and 2 x 16 disc for

tension point shall be used and latest Railway Regulation should be followed.

Insulator string shall be assembled on ground. These shall be cleaned and examined before

hoisting. All accessories shall be properly fitted according to approved drawing. It shall be

ensured that all current carrying parts smooth and without dirt, grit, cuts, abrasions, projections

etc. Insulators with hair cracks or chips or those having glazing defects exceeding half centimeter

square will not be used. Security clips shall be in position for insulators before hoisting. Care

should be taken that ‘W’ spring/security clips are in current position & all splits pins are opened.

11.2 Jointing of Conductor

Jointing of conductor shall be done by splicing sleeves of compression type. All mid span joints

or splices of conductor or earthwire which are subjected to the tension shall be of tension type

and joints or splices of conductor used for jumper connection shall be of non-tension type. Both

of the splices shall be in accordance with the recommendation of manufacturer. The contractor

shall arrange the required compression jointing machine and dies and other necessary tools.

Each part of the joints shall be cleaned by wire brush to make it free from rust or dirt etc. and

proper non-oxide compound shall be placed before final compression is done with compressors.

Jointing shall be to the satisfaction of the Engineer.

The contractor shall be entirely responsible for the proper handling of conductor, earthwire and

accessories in the Site. Handling and transporting of conductor and accessories shall be carried

out in such a manner so to minimise the possibility of damage from abrasion, through rough

handling or dirt and grit getting into reel and on the conductor causing injury to conductor etc.

Particular care shall be taken at all time to ensure that conductors do not become kinked, twisted

or abraded, bird caged in any manner.

If the conductor during operation got damaged, compression type repair sleeves shall be used

with the approval of the Engineer or his representative to repair minor damage to the conductor

provided that


44

a) At the location on the damage on the conductor to be repaired nor more than 1 or 2 or the aluminum strand are damaged over a length of not more than 102 mm.

b) Not more than 2 Aluminum strands in the outer layer are broken and cross sectional area of any other of the damaged Aluminum strands is not reduced by more than 25 percent. All joints or splices or repair sleeves shall be made at least 30 meters away from the structure. No joints or splices shall be made in span crossing over main roads, Railway, river. Nor more than one joints or repair sleeve shall be allowed in one span per conductor.

11.3 Running Out (Paying out) and Stringing (Pulling up) of Conductor

The reels on which the conductors are wound are to be raised from ground so that they are free

to rotate. The conductors are then to be pulled out. Care must taken by the contractor to avoid

any damage to the conductor which are prone to become scratched. The conductor must be

prevented from ‘pying’ too fast and becoming tangled. Suitable methods, proper scaffolding are

to be adopted by the contractor for crossing obstructions or roads or existing power or Telephone

line. Turn table may also be used depending on suitability of work for running out of conductor.

As the conductors are reeled out they are to be hoisted up to the cross arms level and pass

through the travellers comprising of aerial rollers and ground rollers. The travellers shall have a

size and shape most suitable for the type of stringing and size of conductor involved and as

recommended by the conductor manufacturer and DVC. The travellers contact surface with

conductor shall be coated with such materials e.g. neoprene rubber that conductor is not

damaged during pulling up operation. These rollers shall be equipped with high quality ball or

roller bearing for minimum friction. Proper approval regarding the travellers shall have to be

obtained from the representative of the purchaser.

The aerial rollers shall be hung from cross arm of the tower by means of requisite wire rope

slinging such a way that the conductor on the traveller will be at the same height as the

suspension clamp to which it will be secured after final adjustment of tension. Sacking is to be

wrapped over the steel work and under sling to avoid damage to the sling as well as to the

protective surface finish of the steel work.

The pulling up of conductor through traveller shall be carried out in such a manner so that

conductor is not damaged or contaminated with foreign substance and that it may not be rubbed

with rough ground surface.

During pulling up operation the tension in each conductor and earthwire shall not exceed the

design working tension of the conductor at the actual prevailing temperature. After being pulled

the conductor & earthwire shall bot be allowed to hang in the straining blocks for more than 96

hrs. Care should be taken in pulling up so that splices/joints and sleeves do not catch on cross

arms or in the sleeves of travellers. Any catch of this sort may prevent the conductor from

coming slip, as it should. Normally the joining of conductor shall be so made so that the joints are

not required to pass through aerial roller.

11.4 Tensioning,Sagging and Clippling in of the Conductor

The conductor and earthwire shall be sagged in accordance with erection sag tension chart

supplied by the purchaser and as per instruction of the Engineer before they are finally attached

to the tower through the earthwire clamps for earth wire and insulators strings and clamps for

AAAC conductor.

The sag shall be checked in the span which is nearly equal to the equivalent span of the

stringing section. The contractor shall be responsible for any damage caused to towers or to the


45

conductor through over stressing during stringing dynamo-meter and sag boards shall be used to

measure tension and sag. The results are to be checked from the sag tension chart.

Dynamometer shall be periodically checked with standard Dynamometer. The sag also to be

checked when the conductor have been drawn up and transferred from travellers to the insulator

clamps. The conductor shall be clamped within 36 hours or sagging in.

Sagging in operation shall not be carried out under wind, extremely low temperature or other

adverse weather condition, which prevent satisfactory sagging. It should be carried out in the

calm weather and when rapid changes in temperature are not likely to occur.

All conductors shall be temporarily earthed in an effective manner at every section point. Such

temporary earth shall be removed after stringing of the entire line is over and before testing and

commissioning of the line.

11.5 Fixing of Vibration damper and other accessories

Vibration dampers and/or armour rods for conductors shall also be fitted according to the

recommendation of the manufacturers and advised by the purchaser. Anti climbing devices shall

be fitted on towers at a height approved by the Engineer. Danger plate & number plate shall

have to be fitted on all locations and phase marking to be provided. The step bolts shall be

provided on legs of tower and from height above ground level as specified by the Engineer.

Fasteners on all fittings, tower, insulators and conductor accessories shall be secured in position,

the security slips also properly opened and sprung into position.

11.6 Erection of jumpers and suspension insulators to restrict jumper swing

The jumper at the section & angle tower shall be erected as advised by the Engineer. These

shall be formed to parabolic shape to ensure minimum clearance requirements. Non-tension

joints are to be made with the dead end tension clamps to ensure continuity of the line as

directed by the Engineer or his authorised representative.

11.7 Payments

Payments for the complete stringing work with 6 (six) Nos. AAAC conductor shall be made on

per KM basis separately. Complete stringing works include all the work in items 1.10.00 to

1.10.06 and also the fitting of accessories as directed by the purchaser. The contractor shall

quote separate rates for stringing of 6 Nos. AAAC conductor and 1 (one) No. earth wire on per

KM basis. The rate shall be inclusive of handling, storage and carriage of all materials required

for the purpose from contractors stores to work site.

11.8 Final Checking, Testing and Commissioning

After completion of the erection of line final checking shall be made by the contractor at his own

cost with the representative of the purchaser and shall ensure that all the foundation work, tower

erection and stringing has been done strictly according to the specifications given herein and as

per IS & Electricity Act and rules. All works shall be thoroughly inspected keeping in view the

following main points.

1) Finishing of coping with proper grading.

2) Sufficient back filling with proper grading.

3) Verticality of erected tower.


46

4) Proper placing, tightening and punching of bolt.

5) Normal position of the insulator string and clearance of conductor from tower body.

6) Proper sag and tension of the conductor with proper ground clearance as per specification.

7) No damage minor or major to the conductor earth wires, accessories and insulator string

remain unattended. After final checking the line shall be tested for insulation in accordance

with test prescribed by the purchaser and as per I.S. All arrangements for such testing

shall be done by the contractor and necessary labor. Transport and equipment shall be

provided by him at his own cost. Any defects found out as a result of such test, shall be

rectified by the contractor forthwith without any extra charges to DVC. In addition to the

above, the contractor shall be responsible for testing that the total and relative sags of the

conductor and earth wires are within the specified tolerances. Such tests shall be carried

out at selected points along the route as required by the Engineer and the contractor shall

provide all necessary equipment and labour to enable the test to be carried out. After

satisfactory tests on the line and on approval by the Engineer in writing. The line shall be

energised at full operating voltages before handling over.

12 Collection of Materials

Materials will be supplied by the contractor at their own stores at site. Materials as detailed in

SCC will be issued to the contractor by the purchaser for the execution of work either by paper

transaction at contractor’s site stores for the materials under their scope of supply or from DVC’s

departmental stores at Maithon/ Dhanbad/ Giridih/ Koderma/ any other specified store. The cost

involved in handling and transporting of stores and storing the materials and carriage of all

materials to actual erection site shall be quoted as per SCC. Land/sheds for site storing of the

materials by the successful tender shall be arranged at his own cost. The site stores shall be got

approved by the purchaser before storing of the materials. The erection rate should also include

the cost of security arrangement of the materials and tools and plants issued by DVC. The

materials to be supplied and issued to the contractor in phased manner in conformity with the

progress of erection work. The supply schedule would be fixed up by mutual agreement with the

successful bidder after issuance of LOA.

12.1 Materials to be supplied by the Contractor

The contractor shall supply all the materials such as cement, sand, stone chips, gravels, non-

oxide compound, M.S. rod, G.I. binding wire of 18 SWG etc which are not covered under supply

schedule. The cost of these materials including transportation to site shall be included in the

erection rate. The materials to be supplied by the contractor shall be approved by the site

Engineer before use.

12.2 Return of Materials

All materials drawn by the contractor supplied by DVC in excess of those actually used shall be

returned by him at his own cost to the purchaser’s stores at Maithon/ Dhanbad/ Giridih/

Koderma/ any other specified store as per instruction of site Engineer.

Return of all the items as stated above shall be made within one month from the date of

completion of particular work for which the materials were issued. For non-return of the same the

purchaser shall realize the cost in full from the contractor at rates indicated in the schedule apart

from taking any other action as per settled terms and conditions of contract.


47

13 Approval from Respective Authorities

The contractor shall at his cost furnish well in advance before starting erection of the line all

necessary details and drawings as required for obtaining approval from P&T Departmental/Rly. &

other utility or civil authorities etc. All these approval are to be liaisoned & to be arranged by the

contractor as per S.C.C..

14 Measurement of Work Done

Within 4 days from the date of completion of each item of work at each location, measurement

should be taken in the presence of the contractor whose signature should be obtained in the

M.Bs as a token of his acceptance of the measurement. If the contractor fails to be present on

the date of measurement as specified by the Engineer or the authorized representative,

measurement taken by the purchaser shall be final and binding on the contractor, unless specific

written objections thereto are filed with the Engineer within three days form the date of

measurement.

15 Technical Particulars

Some essential particulars regarding the 220 kV D/C & 132 kV D/C transmission line are given in

Annexure –A & Annexure –B for guidance.

16 Completion of Drawings (As executed)

On satisfactory completion of the work the contractor will supply to the Engineer free of cost “As

executed” route profile of the line (one on good quality reproducible & ten copies of prints)

showing therein the actual position and type of towers, double insulator points, forest, Rly, River,

Telecom & Power lines, road crossing together with measured span on a scale of 25 meter to 1

cm horizontal and 2.5 meter to 1cm.vertical.


48

TECHNICAL SPECIFICATION FOR GENERAL

CIVIL WORKS



VIP ROAD

KOLKATA – 700054

A. MATERIALS :

A.01 Cement :

Cement shall be ordinary cement conforming to IS : 269 / IS : 455. Cement shall be kept in clean dry, moisture-proof covered stores. It shall be adequately protected from condensation, rising damp and atmospheric moisture. Sufficient cement shall be stored at all times to ensure continuity of work Not more than ten bags shall be stacked in any tier. Should at any time Engineer-in-charge have reason to consider any cement defective, then irrespective of its origin and / or manufacturer’s test certificates, such cement shall be tested immediately at DVC’s laboratory or a National Laboratory, and until the results of such tests are found satisfactory it shall not be used in any work. The Contractor shall not be entitled to any claim of any nature on this account.

A.02 Fine Aggregates : Fine aggregates (Sand) shall be clean, sharp coarse, gritty to the touch and free from elongated and flaky particles with a fineness modulus between 2.8 and 3.2 It shall be clear and free from any mixture of clay, dust, vegetable matter, mica, shale, loam, salts and organic matter, or other impurities, which may be considered by the Engineer-in-Charge as harmful. Sand containing clay shall be thoroughly washed by the contractor at his own expenses before use. It shall be used in cement concrete work. Fine sand shall be clean, gritty to the touch, free from admixture of clay, loam, salt, organic matter or other impurities and shall pass through sieve No.16. Unless otherwise specified fine sand may be used for sand filling and for mixing with cement for mortar and plaster. It shall not be used for cement concrete work in floors, pavements, reinforced brickwork etc.

A.03 Coarse Aggregates : Coarse aggregates, whether crushed stone or washed and graded gravel shall conform to sieve analysis presented in Table-II of IS : 383.

Stone aggregate shall consist of good, hard and broken stone of the gauge specified and approximately cubicle in shape. It shall be free from dirt, clay, heaves or any organic matter of admixture of soft or decayed stone. Different sizes shall be stacked sufficiently apart or separated with approved wooden bulk heads. Should at any time the Engineer-in-Charge have reasons to consider any aggregate defective or of poor quality, then irrespective of any previous approval or tests, samples of such materials shall be immediately tested and until the result of such tests prove the materials to be satisfactory,

it shall not be used in any work. The contractor shall not be entitled to any claim of any nature on this account. The gravel must be hard and durable, free from clay, moorum, dirt, leaves or any organic matters or admixture of soft or any other foreign materials. The gravel must be uniformly graded and exhaustively and thoroughly washed. The gravel must be approved by the Engineer-in-Charge.


49

A.04 Bricks : Bricks shall be of Class Designation 5 / 2nd class & of uniform standard size. No dimension shall vary more than + 4 mm. Bricks shall be made from selected good earth, free from gravel, saline deposits, other harmful materials well plugged and hand moulded or machine moulded and thoroughly burnt without incipient vitrification to a uniform deep red or copper colour. They shall be regular, uniform in shape and size with a sharp sides and parallel faces and free from flaws, cracks, stones, modules of lime and other objectionable blemishes and shall emit a clear ringing sound when struck. No brick shall absorb more than fifteen (15) per cent of its weight of moisture when immersed in water for twenty four (24) hours. All bricks shall bear a legible stamp on one face. These shall be stacked in 2 rows horizontally and endwise, 50 in each row and 10 bricks high, thus making 1000 bricks in each stack. All bricks shall be subject to inspection and approval and samples shall be submitted before ordering out. The materials supplied shall conform to the approved samples and may be subject to tests as required by the Engineer-in-Charge.

A.05 Water : Water shall be clean, transparent, tasteless and free from organic or deleterious matter in solution or suspension in quantities which may impair the strength or durability of the concrete & brick work. Contractor shall provide his own arrangements and at his own cost for distribution, store, filtration and / or treatment, as necessary of the required quantity of water. The water should be reasonably clear and of turbidity limit 2000 ppm.

A.06 Reinforcement : All reinforcement shall be of tested quality strictly in conformity with the relevant Indian Standards and the purchaser shall check and ensure that appropriate test certificates of materials are available to his satisfaction. Otherwise, necessary tests shall be made by the Contractor at his own cost to ensure that the quality and physical properties of the materials used conform to the specification. No complaints or claims shall be entertained on this account. All reinforcement materials, before its final use, shall be free from loose mill scales, loose rust, oily or bituminous coating or injurious adherents. Pitted and otherwise defective rods shall not be used. The Contractor shall check, ensure and procure in time, as necessary, the reinforcement materials required for the continuous scheduled progress of the work till completion. All reinforcement steel shall be suitably stacked and stored by the Contractor to protect it from damage by corrosion, and to prevent distortion of section in long lengths.

A.07 Mortar : Unless otherwise specified or directed, the mortar shall consist of one (1) part cement and four (4) parts sand by volume for all brickwork, inclusive of 127 mm partition. It shall be mixed dry and then wetted to stiff but workable paste. The mortar shall be used within thirty (30) minutes of mixing. Mixing of mortar shall be done on a platform of approved type.

A.08 Structural Steelwork : a) Steel :


50

All structural steel shall conform to IS : 2062 Grade A (latest) & shall be of tested quality, recent manufacture & free from mill scales, slag intrusions, laminations, pittings, flake rusts etc.

b) Zinc :

The Zinc required for galvanising shall be of quality Zn 99.99 & shall conform to IS : 209 (latest).

c) Bolts & Nuts :

All M.S. Bolts & Nuts shall conform to IS : 6639 (latest) & IS :12427 (latest). The step bolts should conform to IS : 10238 (latest). The bolts shall be of property class 5.6 as specified in IS : 1367 (Pt.-3)-1979 & nuts shall be of property class 5 as specified in IS : 1367 (Pt.-6)-1980. All bolts & nuts shall be galvanised & tested in accordance with IS : 2633 (latest) & shall have hexagonal heads & nuts, the heads being forged out of the solid, truly concentric & square with the shank which must be perfectly straight. Fully threaded bolts shall not be used. The length of bolts shall be such that the threaded portion will not extend into the plane of contact of the member. The threaded portion of each bolt shall project through the nut at least 6 mm when fully tightened. All nuts shall fit hand tight to the point where the shank of the bolt connects to the head. M/s. GKW / TATA /ASP / BI make bolts & nuts shall be used. Diameter of bolt shall be 16 mm.

d) Washers : All pack washers shall be made of steel conforming to IS : 2062 Gr. A. (latest). The plain washers & heavy washers shall conform to IS : 2016 & IS : 6610 (latest) respectively. 3 mm square section spring washers of positive lock type shall be used with all bolts & nuts & shall conform to IS : 3063 (latest) and shall be electrogalvanised in accordance with service conditions 3 of IS : 1573 (latest)

B. EARTHWORK IN EXCAVATION & FILLING :

B.01 Preparation of Site and Foundation :

All rubbish, brush-wood, trees etc. shall be cleared 50 m. away from the site. All roots to be grubbed 1 m. below ground level and holes filled with earth well rammed. Waste materials from the clearing operations shall be burnt or removed and satisfactorily disposed of in order to avoid unsightly appearance, unless otherwise stated.

Lining Out Preparatory to lining out, foundation plan to be prepared by the Engineer-in-Charge, pegs, strings, flange, pillars and labour required for setting outwork or construction lines or benchmark as may be required, shall be approved by the Contractor and no extra rate will be payable to the contractor.

B.02 Excavation for Foundation : Trenches for foundation, footing, pits, drain etc. shall be taken out to the full width of lowest course of footing and to exact length and depth as shown in drawing or as may be directed by the Engineer-in-Charge, if required. The sides shall be left plumb where nature of soil admits, but they must be stepped back or shored up carefully where they show a tendency to fall in. No excavated materials shall be deposited within 2.0 m. of edge of foundation or twice the maximum depth of foundation whichever is more. In case excavation is done wider or deeper than the size & depth of foundation / trenches / drain as shown


51

in the drawing, the Contractor shall fill up extra width or depth at his own expense with concrete, or sand watered and rammed as the Engineer-in-Charge may direct. Bottom of foundation trenches shall be dressed level both longitudinally and transversely and on completion shall be watered and well rammed. If any soft places come to sight on inspection or by ramming they shall be dug out or dealt with as ordered before putting concrete. The foundation trenches shall be inspected and passed by the Engineer-in-Charge before any concrete or masonry work is commenced and the Contractor shall hold and order to the effect. Measurement of excavation shall be taken on the area of bottom of foundation multiplied by depth of foundation. Excavation for sloping or stepping the sides shall not be paid for.

Contractor's rate for the item shall include :

a) Lifting and removing excavated materials, surplus earth upto a lead of 150m.

b) Provision of drain as required to prevent water accumulating round foundation in the event of rain.

c) All shoring, sheeting and strutting required. d) Pumping out of bailing out water. e) Removal of loose stones or brickbats met with during course of

excavation. f) Watering and ramming foundation bed.

B.03 Earth / Sand filling and filling of Embankment: a) For filing up of low lying areas and for construction of embankment, good

excavated soil free from vegetation and organic matter, stones, brick bats etc. shall be used. All filling in earth shall be laid in layers not exceeding 150 mm thick and rammed, tamped, rolled, watered and thoroughly compacted to consolidate properly.

b) For all backfilling with sand, clean approved river sand will be used, free from foreign matter and impurities. The sand fill shall be fully saturated with water and well vibrated mechanically to achieve full compaction. After compaction, water shall be drained out through weep holes or otherwise in an approved manner.

c) Prior to filling of low lying area or before commencement of embankment

construction, the area shall be cleared of all vegetation growth and the original surface shall be stripped to required depth of 150 mm. The stripped surface shall be ploughed / harrowed and well moistened before depositing new material on it.

d) No bush, roots, sod or other perishable or unsuitable materials shall be placed in

the fill / embankment. The suitability of each part of the foundation for placing embankment materials thereon, and of all materials for use in the embankment construction will be determined by the engineer. It is the duty of the contractor to deliver such specimens of materials to be taken from the borrow pits and the embankment fills, as directed by the Engineer or his representatives to the laboratory.

e) The cost of taking and transporting the materials for testing to the laboratory is to

be included in the unit rates for excavation. The actual cost of making the tests is to be borne by DVC. Similar procedure will have to be followed for compaction control tests.


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f) The material shall be spread uniformly in layers not exceeding 150 mm after compaction in depth before compaction, with optimum moisture as established by laboratory test. The layers shall be deposited in an approximately horizontal position with slight slopes.

g) If any equipment is used which is not capable of spreading materials in layers

not exceeding 150 mm after compaction in depth, blade graders or other similar approved levelling devices must be used. The fill / embankment shall be compacted as evenly and densely as possible (not less than 95% of Standard Proctor density) by routing the hauling equipment over the layers already in place, distributing such layer over the entire length and width of the previously placed material. Compacting machinery such as roller shall be used for compacting the earth fill.

h) The material in each layer, while being compacted by rolling, shall contain within

practicable limits the optimum amount of water for compacting purposes, and this optimum water content shall be uniformly distributed throughout the layer. The application of water to materials for this purpose shall be done at the site of excavation as far as practicable and shall be supplemented as required by sprinkling on the fill / embankment. Harrowing or other working of the material may be required to produce the required uniformity of water content. In case of excessive moisture content, the material should be allowed to lie until the excessive moisture has evaporated or drained out before the layer is rolled. In view of the danger of over rolling the impervious core or blanket, if any, heavy hauling equipment should be spread out over the wide area. Rolling or the passage of heavy equipment on material with relatively high water content tends to cause local shear failure.

i) Each layer of material shall be compacted by passing the specific roller over the

entire surface. The exact number of passes required shall be determined by the Engineer.

j) When any mechanical equipment used for spreading and compaction becomes

inoperative or suffers a break down, all other mechanical equipment used for placing and spreading materials should cease operations until the equipment used for compaction is again in operation.

k) For embankment construction, embankment shall initially be raised to a level

600 mm below the final level. Superfluous materials on its slopes shall be removed and placed on embankment to raise it to the desired top level and the slopes trimmed to specified slopes. The contractor shall ensure that the finished slopes are neatly trimmed and fully compacted.

l) Contractor shall include in his rate for construction of embankments, stripping of

top soil, clearing jungles, bushes etc. and any other process to get the good earth in the borrow area also. No borrow area shall be made without the Engineer’s approval.

m) Compaction control tests for construction of embankment : 2 Nos. dry density test of compacted layer to be conducted for every 300.0 Cum.

of compacted earth work or part for every layer compacted and degree of compaction attained determined


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C. CONCRETE :

C.01 Code of Practice : All concrete work shall fully comply with the latest edition of Indian Standard Specification IS : 456, "Code of Practice for Plain and Reinforced Concrete".

C.02 Vibration : Approved mechanical vibration for all structural and reinforced concrete shall be mandatory. Immersion type vibrators (65 mm and / or 75 mm dia and 500 mm to 600 mm long) with a minimum vibration of 8000 revolutions / minute shall be used. Use of pneumatic and / or electrical vibrators is mandatory.

C.03 Cement Concrete in Foundation ( Mass Concrete ) : a) i) Materials will be as per specification.

ii) Concrete to conform to IS : 456 and it shall be of Nominal Mix. b) i) Consistency shall be frequently measured by carrying out slump

test. Minimum quantity of water for required workability shall be used .

ii) Proportioning and mixing shall be as specified in the Reinforced Concrete (C.04)

c) Mixing cement concrete - Machine Mixing : Right proportion of materials shall be loaded in mixing drum and sufficient water added in accordance with the water-cement ratio desired. It shall be kept rotating for 1/2 to 2 minutes till all materials are mixed thoroughly and then the concrete shall be discharged in one operation over a level platform and thereafter turned over once before being conveyed. d) Hand Mixing :

Hand mixing shall be done on a watertight brick platform (at least 4m x 2.5m) with strips fastened along 3 sides to prevent materials being washed or shoveled off during mixing. Where hand mixing is allowed, cement and sand shall first be mixed dry thoroughly by turning over backward and forward several times. This dry mortar shall then be spread over the top of premeasured stack of dry aggregate. The whole shall then be thoroughly incorporated by turning over backward and forward at least 5 times to ensure a thorough mix. To this, water should be added from a can fitted with a gradual and the whole stack turned over and over again till every ballast is sufficiently coated with mortar. No excess water should be used. The whole operation shall not be taken more than 15 minutes. If moist sand is used allowance for bulking shall be made.

Unless otherwise mentioned in the schedule, the mixing of concrete should be done by the machine to be approved by the Engineer-in-Charge. No hand mixing concrete will be allowed unless specially permitted by the Engineer-in-Charge. In case of such hand mixing being permitted, 10% extra cement on this account will be added at Contractors expense.

e) Depositing the Concrete :

Before depositing the concrete, debris shall be removed from the space to be occupied by the concrete. The concrete must be used while fresh. It shall be laid (not thrown) in layers not exceeding 150 mm in thickness and shall be well and


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quickly rammed with 6 kg iron rammer until mortar creams to the surface. Square rammers must be used for consolidation of the edges. In laying consecutive layers, lower course shall be well watered and made rough before upper layer is laid. The time from starting of mixing to ramming in final position shall not take more than 30 minutes. Re-tampering of concrete which are partially set is absolutely prohibited. Suitable planks and gangway shall be proved to prevent traffic over the surface of the work. Concrete shall be cured keeping it wet for 15 days. The period, method of curing and method of protecting concrete during curing are subject to approval of Engineer-in-Charge. The rate shall include in addition to provision of materials, mixing, placing curing and finishing of concrete and contrivances for curing, if any. Holes for passage of water wherever necessary and holes for uprights of door frame, are to be provided during construction by the Contractor within the rates.

C.04 Reinforced Concrete : All reinforced concrete will be either with M-15, M-20 or M-25 concrete. Nominal Mix proportion 1:2:4, 1:1.5:3 & 1:1:2 by volume shall be taken as equivalent to M-15, M-20 and M-25 respectively. Characteristic compressive strength of 15 cm cube at 28 days for M-15, M-20 and M-25 mix is 15 N / Sq.mm , 20 N / Sq.mm and 25 N / Sq.mm respectively. Cement :

Cement conforming to I.S. : 269 or IS : 455 shall be supplied by the contractor. Water :

Water shall be arranged by the Contractor at his own expenses, its quality should conform to specification. Reinforcement :

Steel reinforcement shall comply with the requirements of the latest edition of IS : 432 or IS : 1786 (latest). All steel shall be of tested quality. If demanded by DVC the contractor shall submit the manufacturer’s test certificate for steel. All bars shall be free from grease, oil, dirt, scale, loose rust, and bituminous materials. All bars shall be thoroughly cleaned before being fabricated. Pitted and defective rods shall not be used. All bars shall be rigidly hold in position before concreting as per requirements of the latest edition of IS : 2502. No welding of rod shall be allowed. Laying of Reinforcement bars shall be in accordance with relevant I. S. specifications unless otherwise specified. Lap lengths shall not be less than the minimum values specified in the relevant codes of practice. The laps shall be staggered. Dowel bars shall be provided wherever required or as directed by the Engineer or as shown in the approved drawings. Special attention shall be given to proper and adequate reinforcement where the section of the concrete member changes. The horizontal distance between parallel reinforcement bars in row shall not be less than the greatest of the following : a) The larger diameter if the diameter be unequal. b) Diameter, if the diameters are equal. c) 6 mm. more than the nominal maximum size of coarse aggregate.

The vertical distance between two rows of reinforcement bars shall be not less than 12 mm unless they are cross reinforced or lapped. Reinforcement bars


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shall be bent by machine or other approved means. All the bars gradually and correctly bent to shape shall be used and the bends and shapes shall comply strictly to the dimensions in the approved drawing. No reinforcement shall be bent when in position in the work without approval whether or not this is partially embedded in concrete. Reinforcement shall be accurately fixed and maintained in position by approved means. Bars intended to be in contact at crossings shall be securely bound together at all such points by annealed galvanised Iron wire of approved gauge. Placing of reinforcement shall be completed well in advance of concreting. In case reinforcement bars are in coil form, straightening of the same shall be done by the contractor. Shuttering and formwork :

The formwork shall conform to the shape, lines and dimensions shown in the approved drawings. It shall be constructed as to remain sufficiently rigid during placing and vibration of concrete and to prevent bulging of formwork. It shall also be strong enough to withstand the weight of men and materials and scaffolding hung therefrom. The formwork and joints shall also be sufficiently tight to prevent loss of liquid from the concrete. Leaking joints shall be caulked. The formwork shall be such as to ensure a fairly smooth finish free from honeycombs, air bubbles, fins, bulges, depressions prominent grain marks of wood etc. The finish expected would be equivalent to that which would have been obtained had plywood or steel lines shuttering been used. Timber, if used for shuttering shall be well seasoned, free from sap, shaked, loose knots and work holes. Faces coming in contact with concrete shall be free from adhering grout, plaster, paint, projecting nails, splits or other defects. Connections shall be so constructed as to permit easy removal of shuttering and shall be either screwed, bolted, clamped, wired or otherwise secured so as to be strong enough to retain the correct shape during consolidation. Necessary provision shall be made for fixing anchor bolts, sleeves, or any other devices as shown in the approved drawings or as directed by the Engineer. Shuttering shall be provided for the top faces of the sloping work and anchored to prevent floatation where the slope exceeds 1 (vertical) : 2.5 (Horizontal).

Care shall be taken to see that the formwork is perfectly cleared and two coats of approved mould oil / any other approved materials applied before placing concrete. Such coating shall be insoluble in water, non-staining and non-injurious to the concrete. It shall not become flaky or be removed by rain or wash water. Care shall also be taken to prevent contact of the mould oil with the reinforcement. Bolts crossing through water retaining members for the purpose of securing and aligning the formwork shall not be used unless effective precautions are taken to ensure water tightness after removal. Any steel left in the structure shall be adequately protected against corrosion. Formwork shall not be struck before the expiry of the following period : a) Walls, columns and vertical sides of beams - 48 hours b) Slabs (props left under) - 7 days c) Slabs - removal of props - 14 days d) Beam soffits - 21 days.

Striking of forms :

Shuttering shall be removed without shock or vibration by gently releasing the wedges. The contractor shall record on the drawings or elsewhere, as approved, the date on which concrete is placed in each part of the work and the date of removal of shuttering. The consequences arising during the removal of the shuttering shall be contractor’s entire responsibility.


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Re-use of forms :

Before re-use all forms shall be thoroughly cleaned as specified earlier and may be re-used with the approval of the Engineer. The contractor shall, however, equip themselves with sufficient shuttering and formwork to continue with the work uninterruptedly.

Concrete proportioning :

In proportioning concrete, the quantity of both cement and aggregate shall be determined preferably by mass. Water shall either be measured by volume in calibrated tanks or weighed. The proportions of nominal mix concrete shall be in accordance with Table 3 of IS : 456. The amount of water to be added shall be adjusted to compensate for any observed variations in moisture content. In the absence of exact data, the amount of surface water may be estimated as per values given in Table 4 of IS : 456. Incase uniformity in the materials used for concrete making has been established over a period of time, the proportioning may be done, with the permission and approval of Engineer-in-Charge by volume batching and periodic checks shall be made on mass volume relationships of the materials. In volume batching, if the fine aggregate is moist due allowance shall be made for bulking in accordance with IS : 2386 (Part III). Concrete shall be mixed in mechanically operated batch mixers. Water shall not be admitted into the drum of the mixer until all ingredients constituting the batch are in the drum and mixed dry for one minute. Each batch shall be mixed until the concrete is uniform in colour and for a period of not less than two minutes after all the materials and water are in the drum. Partly set or excessively wet and re-tampered concrete shall not be used. Such concrete shall be immediately removed from the site. Each time the work stops, the mixer shall be cleaned out and when commencing the mix again, the first batch shall have 10% additional cement to allow for adhesion to the drum. In exceptional circumstances such as mechanical break down of mixer, work in remote areas or when the quantity of concrete work is very small, hand mixing can be done, with the approval of Engineer-in-Charge, subject to adding 10% extra cement at the cost of Contractor. Concrete shall be handled from the place of mixing to the place of final deposits rapidly as practicable by methods which will prevent segregation or loss of ingredients. It shall be deposited as nearly as practicable in its final position to avoid re-handling or flowing. Mixing and distributing equipment shall be kept free from set concrete. Before proceeding to place concrete, the shuttering shall be realigned, if necessary, and water and rubbish removed therefrom by approved means. No concrete shall be placed until the forms and reinforcements are approved by the Engineer. The interval between addition of water to the dry batch and the completion of placing of concrete shall not exceed 30 minutes. The concrete shall be placed in the final position and shall not be disturbed thereafter. Concrete shall be placed in the shuttering by means approved by the Engineer and shall not be dropped from a height or handled in a manner which will cause segregation. Special care shall be taken in this respect while recommencing the work at a construction joint. Accumulation of set concrete on the reinforcements and shuttering shall be avoided. After the concrete has been placed it shall be compacted by approved mechanical vibration and thoroughly worked round the reinforcements into the correct form and shape. Vibrators must be operated by experienced men and over-vibration shall not be permitted. Some hand tampling of concrete may be necessary and the same shall be done


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if so found necessary or if directed by the Engineer. Care must be taken to ensure that the reinforcements and formwork are not displaced or disturbed during placing of concrete. No concrete shall be placed in wet weather. Concrete that has been washed away by rains shall be entirely removed, if there has been any sign of cement and sand having been washed away from the concrete mixture. Suitable precautions shall be taken to protect fresh concrete against rains before leaving the work unattended. Accumulation of water on freshly laid concrete surface shall not be permitted. Any leakage of cement grout through the shuttering or elsewhere during the concreting shall be immediately caulked properly by coir mastic or any other approved materials. Concrete shall be placed continuously until completion of the part of work between construction joints. This shall be strictly followed in the case of water retaining structures. If stopping of concreting become unavoidable at any other section a construction joint shall be made where the work is discontinued as specified. Concrete which is in the process of setting shall not be disturbed or shaken. Slots, openings or holes shall be provided for bolts, sleeves, anchors, fastening etc. embedded in concrete as shown in the approved drawings or as directed by the Engineer. These shall be provided in the proper places as shown in the approved drawings and any deviation therefrom shall be set right by the contractor at his own expense.

C.05 Construction Joints: The Contractor shall provide all required construction joints as shown in the Engineer’s drawings or as directed by the Engineer prior to commencing any specified work. Such joints shall be located and constructed to least impair the structural strength. Unless otherwise specified or approved the construction joints shall be located as follows : Columns : 75 mm below the lowest soffit of the beams supported by it. Beams : No joint as far as possible, but if unavoidable, the joint shall be

at midspan and shall be vertical joint with a rebate at mid-depth. Slabs : Parallel to the principal reinforcement, but if this is not possible, then at mid-span.

Before depositing fresh concrete at a construction joint the hardened surface shall be well scrubbed with steel wire brushes and thoroughly cleaned by compressed air and then thoroughly wetted. Excess water shall be removed. A 13 mm thick layer of cement and sand grout of same ratio as the cement and sand the concrete mix shall then be applied to the wetted surface and the fresh concrete shall be thoroughly worked against this prepared face before the grout sets. Where the concrete has not fully hardened all lattance shall be removed by scrubbing the wet surface with wire or bristle brushes, care being taken to avoid dislodgement of particles of aggregate. The surface shall be thoroughly wetted and all free water removed. The surface shall then be coated with neat cement grout. The first layer of concrete to be placed on this surface shall not exceed 150 mm in thickness and shall be well rammed against old work, particular attention being paid to corners and close spots. The above works of construction joints are deemed to be included in the items of concrete works and no separate payment shall be made for the same. However, when required, suitable dowels shall be provided at the construction joints for which payment shall be made as per reinforcement steel bar item.


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C.06 Finish : Exposed concrete surface shall be smooth and free from blemishes. While concrete is still green, i.e., just after the removal of shuttering the surface of concrete shall be carefully gone over and any hole, honey comb etc. noticed shall be filled with cement mortar 1 : 1 unless otherwise directed by the Engineer-in-Charge. Newly placed concrete shall be protected from rain, sun or wind. The immature concrete shall be protected from damage by debris, excessive loading, vibration, abrasion, deleterious substances and other materials that may impair the strength and / or durability of concrete by approved means.

C.07 Protection and Curing : All newly placed concrete shall be adequately protected from harmful atmospheric effects, shock and detrimental vibrations. Adequate steps shall be taken to prevent floating or flooding. Vertical faces of concrete shall be adequately covered with a layer of absorbent Hessian or equal, which shall be kept thoroughly and continuously wet for at least ten (10) days following the date of placement. Exposed flat and horizontal faces (e.g. top of mat or slabs) shall be made to retain adequate quantity (50 mm) of standing water by ponding. The standing water shall be maintained constantly for a least ten (10) days following the date of placement.

C.08 Precast Concrete : The Contractor shall furnish and install required covers for cable trenches and ducts, surface water drains, trenches, inspection chambers and holes. The precast covers shall be manufactured unwrapped, true to shapes and forms, properly cured etc. in accordance with the Engineer’s drawings. All joints shall snugly fit together for the full length. All planks shall be of removable type, with at least two (2) collapsible galvanised M.S. lifting hooks and shall bear at each support at least 50 mm. Necessary openings in coves shall be provided, as required. Anti-slip treatment shall be given to the finished surfaces, wherever required. All surfaces exposed to atmosphere, except for cover of water drains shall be plastered and jointly grouted with 1:3 cement mortar unless otherwise directed or specified. The concrete shall be M-15, M-20 or M-25 as specified in the dwg. Materials also shall conform to specification as stated except that coarse aggregate shall be of size specified in the drawings or as per Engineer’s directions. The Engineer may take specimens for testing to ensure the quality or work. Cost of such specimens and tests shall be borne by the Contractor.

C.09 Encasement of Structural Steel : Structural steel work as shown in the drawings or as directed, shall be encased in concrete or brickwork. Before encasing, the portion of steel to be encased shall be thoroughly cleaned with wire brush to remove loose scales, rust, paints etc.

C.10 Grouting : The contractor shall grout base plates of steel structures as per drawings. Unless otherwise specified on the drawings or directed, grout not exceeding 25 mm nominal thickness shall consist of one part cement, one part metallic aggregate (such as Embeco or approved equivalent) and one part fine aggregate by weight, thoroughly mixed with with water just sufficient to make the


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mix suitable for the required application. The water-cement ratio shall in no case exceed 0.50. However, if greater flowability is required at any particular location, the water-cement in the mix may be increased keeping the water cement ratio 0.50. Aluminium powder of unpolished variety shall be added to the grouting mix at the rate of one teaspoonful to a bag of cement as and when directed. The Aluminium powder shall be thoroughly mixed with cement to ensure its uniform distribution in the mix. For grout of over 25 mm nominal thickness, the mix shall consist of one part cement, one part metallic grouting aggregate and one and half parts course aggregate (10 mm maximum size) by weight. Ready mix grout like SHRINKKOMP, CONBEXTRA GP2, SIKA GROUT 214 or approved equivalent may also be used. Before placing of grout, the concrete surface shall be thoroughly cleaned of loose materials by means of compressed air jet and wetted to facilitate the flow of grout. Form work, where necessary, shall be placed around the area to be grouted and suitably braced to prevent slipping during grouting operations. The grout shall be laced by whatever means that is most practicable. The grout may be done by ramming, by pressure grouting, by gravity, by pumping or by pouring in place. Any method used shall first be got approved. The grout shall be thoroughly compacted and all air pockets eliminated. Whenever practicable, grout shall be poured from one end or side only to avoid excessive air entrapment. After sufficient set has been attained, the shuttering shall be removed and the excess grout shall then be trimmed away. Every precaution shall be taken to prevent surface temperature variation for a period of 7 days after placing of grout. Immediately after the final finishing is completed and the grout is hardened sufficiently, the surface shall be thoroughly wetted and be kept wet for a minimum of 7 days. The grout thickness shown in the drawings will be nominal and actual amount will depend on the actual finished height of the concrete foundation. No extra payment will be paid for this reason.

D. BRICKWORK :

D.01 Cement Brickwork : a) Brick, sand and cement shall conform to specification. Unless otherwise

specified brick work shall be of 2nd class bricks of approved quality laid in mortar. Work shall be strictly as per drawings. Bricks shall be soaked in water for at least 6 hours. Bricklined tanks of sufficient size, to admit this being done, must be constructed by the Contractor at site of work and filled up after execution of work at his own cost.

b) Cement and sand shall be measured and mixed dry, minimum quantity of water to ensure workability shall be added and the mortar turned over and over, backward and forward as approved by the Engineer-in-Charge. All cement mortar shall be used up within 30 minutes of mixing.

c) The brickwork is to be of English bond with frog upwards. No more half brick shall be used than are necessary to complete the bond.

d) In laying each course brickwork shall be truly level and in perfect bond. All bricks being thoroughly bedded and flushed with mortar. No mortar joint shall exceed 10 mm in thickness.

The work shall be carried up regularly. The maximum height of brickwork erected in any day shall not exceed one metre and no portion of work shall be left more


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than one metre lower than another. Temporary steps left during construction shall be raked back according to bond and not toothed so that when work is continued the new brick will be laid over those previously laid.

No mortar joints shall exceed 10 mm thickness and shall be less than 6 mm thickness, unless otherwise specified or approved by Engineer-in-Charge. The Contractor shall provide planks on which the wetted bricks shall be stacked before laid on the wall.

All brickwork shall be kept wet for at least 10 days after it is laid. The work shall be left flooded at the end of each day’s work by making through with mortar fillets.

All the fixtures shall be built into the walls in their correct position as work proceeds, joints of all brickwork shall be raked out while the mortar is still green to a depth of 20 mm to ensure a good key to plaster. All scaffoldings shall be provided by the Contractor. The Contractor shall be responsible for any damage or injuries resulting from all erected scaffolding. The Contractor’s rate for brickwork shall include cost of all scaffolding, curing etc. and shall apply to all brickwork in steps, string course over ghoondies in roof and all projections, curves etc. The measurement for payment shall be made for the actual volume / area of work executed. Deduction for opening shall be as per I.S. Specification.

D.02 Cement Plaster : Fine sand shall be used in plaster. The plaster shall be of thickness as specified.

But the Contractor shall allow in his price for any dubbing required due to irregularities of brickwork. It shall be composed of 1 part of cement to 4 part of sand unless otherwise specified.

The mix shall be thoroughly mixed and the wet plaster being used within half an hour of being mixed. Surface to be plastered shall be wetted for 24 hours and joints of brickwork raked out 20 mm deep before plaster is put in. Mortar which has began to set shall not be used for plastering. Plaster in any place shall not be thinner than specified. Plaster shall be kept wet for a period of 10 days. All internal and external angles shall be rounded to 25 mm radius. The area of all corners, doors and windows shall have richer mortar 1: 3 over a width of 75 mm on either side and Contractor’s rate shall include this. The rates for plaster shall also include (a) Plastering the surface and Corner and rounding at angles, (b) Preparing, clearing and watering surface, (c) Watering and protecting plaster after completion, (d) Provision, erection and removal of scaffolding.

D.03 Cement Punning ( Neat Cement Finish ) : Punning (neat cement finish) when specified shall be done as soon as the

surface of the plaster has hardened a little and shall not be delayed too long after the same.

The required quantity of cement and water shall be thoroughly mixed together into a paste of the desired consistency. The cement paste shall then be applied to a thickness of 1.5 mm. or as specified over the surface with a small steel trowel and polished well. Punning shall in general be done from top to bottom in one operation to eliminate joint marks.

D.04 Scaffolding : The unit rate for all the items of work specified above shall include the cost of all

required scaffolding. All scaffolding shall be strong, right and shall have two uprights, or be of the swinging type supported from outrigger beams at appropriate locations to avoid the objectionable practice of leaving holes in the


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walls. Horizontal and vertical diagonal bracings shall be provided. Single scaffolding shall not be allowed for any work. Stage scaffolding, independent of the walls, shall be provided for ceiling plaster.

All scaffolding shall be kept safe to men and materials and be fireproof as far as possible. Records of its inspection shall be properly maintained.

E. FLOORING AND FLOOR FINISHING :

E.01 Single Brick Flat Soling in Flooring :

Second class bricks shall be used for the soling, and shall be soaked in water for at least 6 hours before use. Before laying the soling, the bed on which it is to be laid shall be well watered, rammed and surfaced evenly to the proper level and slope necessary and as directed by the Engineer. On the top of this 12 mm thick layer of fine sand shall be laid and well rammed and the surface made even. The bricks shall be laid breaking joints using sand at the joints. The bricks shall be carefully struck with a hammer to press against one another through the mortar so that the joints are not more than 10 mm thick. The excess of mortar rising through the joints shall be scrapped off. Grouting the joints with this mortar shall not be permitted. Care shall be taken in laying with bricks so that the entire surface shall present an even and compact appearance Dust, dirt or earth shall not be allowed to adhere to the surface and shall be thoroughly clean until concrete is laid on the top of it.

E.02 Cement Concrete Flooring : If not otherwise specified the flooring shall be 75 mm cement concrete, 1:3:6

using stone aggregate of 20 mm and down size. The work shall be carried out as per cement concrete for foundation. The top surface shall be leveled and finished smooth with straight edge and trowel and left clean to receive the floor finishing.

F. STRUCTURAL STEELWORK :

F.01 Fabrication : i) The fabrication of structures shall be in accordance with relevant clauses

of IS : 800 & IS: 802 (Part-II) latest. ii) All parts of the structures shall be fabricated in accordance with the shop

drawings approved by DVC. iii) Structures shall be of bolted construction unless otherwise specified.

Unless specially demanded, welding at no point shall be permitted. iv) Structures shall be accurately fabricated, to bolt together easily at the site

without any undue strain on the structural members or in the bolts. Otherwise, the structure or parts of it will be rejected.

v) Structures demand accurate drilling/punching of holes with high standard of workmanship. No bolt holes shall be more than 1.5 mm larger than the corresponding bolt diameter. Holes shall be drilling or punched to jig, but drilled holes shall be preferred and they must be perfectly circular and no tolerance in this respect is permissible.

vi) All steel sections, before any cutting work is started, shall be carefully levelled, straightened and made true by methods which shall not injure the material. They shall again be trued up after being punched and drilled. No rough edges shall be left. Bends, if any shall be thoroughly cold straightened without injury. Shearing shall be neat & edges shall be


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planed & trimmed, as necessary. vii) Workmanship & finish shall correspond to the best & modern practice. All

similar parts be made interchangeable.No rough edges shall be permitted any where throughout the work.The structure shall be so fabricated that all parts be accessible for inspection & cleaning. Drain holes shall be provided at all points where pockets or depressions are likely to hold water.

F.02 Marking of Members :

Each individual member shall carry a stamped mark (number) assigned to it in the approved Drawings. These stampings shall be done by a metal die before galvanising and on optimum depth so as to be clearly legible after galvanising. Further more, the mark No. should be stenciled in indelible ink on each member after galvanisation.

F.03 Galvanisation : The galvanising shall be as per IS :2633 (latest). Zinc coating over galvanised surface of structure members and threaded fasteners shall not be less than 610 gms per sq.m. & 375 gms per sq.m. respectively. Uniformity of galvanisation shall be determined by the Preece Test. The samples shall withstand four one minute dips for passing the test. Contractor should submit regularly the result of all the tests performed, to DVC for approval. Corporation’s Engineer or their authorised representatives will witness the tests. Hot dip Galvanizing of the structural members shall conform to IS-2629 (latest) and IS-4759 (latest) and that for bolts & other fasteners, shall conform to IS-1367 (Part-XIII) latest. All galvanizing material shall withstand test as per IS 2633 (latest). The weight of Zn Coating shall be determined as per method stipulated in IS-2633 (latest)

F.04 Painting : Surface preparation is very important before actual painting is made unless otherwise specified. All steelwork shall be given one coat of shop paint applied thoroughly and evenly to dry surfaces which have been cleaned. Paints to be used for shop coat of fabricated steel shall conform to IS :2074 (latest). Unless otherwise specified two coats or red oxide paint should be provided as primer (one coat at shop & the other at site after erection) before applying two coats of finish coat. The paint should be manufactured by Berger, Jenson & Nicholson and / or Asian Paints. All paints & primer shall be of standard quality & procured from approved manufacturer & shall conform to the provision of relevant IS Codes. Relevant IS Codes for various types of paints are as follows :

i) IS : 2074 : Red-oxide zinc chrome paint. ii) IS 2932 : Synthetic enamel paint. iii) IS : 158 : Anti-Corrosive black bituminous paint. iv) IS : 2339 : Aluminium paint

For other specifications refer (G).

F.05 Erection : The complete erection of the steel work is a part of a contract and the contractor shall be responsible for determining the erection procedure as well as for providing temporary bracing and connections and shall be liable for loss or damage resulting from faulty erection. All materials shall be effectively protected from injury, while at the shop/in transit, until erection complete and inspected & accepted.


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The structural steel erection work shall commence only after the foundations have been checked and passed by the Engineer. The work shall include, besides the scope specified elsewhere in this specification, the following.

a) Straightening and repairing on ground and materials damaged in transit and assembling, bolting, riveting or welding of all connections on ground or in position. Straightening of erected members will not be permitted. The structures shall be ground assembled in largest possible size which can be erected with the equipment available.

b) Varnishing and applying the base coat of paint damaged in transit and/or site connection and splice.

The Contractor shall erect all necessary guys and braces to ensure proper alignment and stability until all members are permanently connected. Such temporary guys and braces shall be maintained in place until, in the opinion of the Engineer they can be removed without danger to the stability of the structure.

As each part of the work is erected, it shall be passed by the Engineer. This particularly applies to accurate plumbing of all stanchions or columns, levelling, setting, aligning and fixing of the various parts and adjusting of bearings. Free movement shall be ensured where required for contractions and expansions. Variations from Engineer’s drawings shall be checked, noted and reported to the Engineer immediately. Prior to erection the Contractor shall ascertain from the Engineer as to which parts will be inspected and passed from time to time. Such passing will not, however, exonerate the Contractor from this responsibility for proper erection,

The Contractor shall furnish, at his own expense, necessary staging and hoisting of all materials or equipments required for the erection of the structure and shall remove and take away when the work is completed. Where directed, the staging and hoisting equipment and materials shall be non-inflammable.

All necessary cutting, punching, drilling, welding & fitting including cutting & making good concrete and/or masonry or other adjacent work for installation of the structural & miscellaneous steelwork shall be included. The contractor shall also make necessary modifications to the existing or already staled work (by other contractors) & make firm connections thereto of the structural & miscellaneous steel as directed or as approved by the Engineer.

Welding work shall be performed only by qualified welders who have passed qualification tests in accordance with the codes.

G. FINISHING ITEMS :

G.01 Painting :

Materials : All paints, oils, other materials and labour for painting shall be provided by the

contractor and included in the contract rate for painting or as specified. Ready mixed paints shall be used exactly as received from the manufacturers and without any mixture whatsoever except without the previous approval of the Engineer-in-Charge. Also refer (F.04)

Preparing the surface for painting :

i) For new woodwork : The surface shall be cleared thoroughly of all dust and dirt and sand papered. All projections such as glue or whiting spots, all tool marks and other irregularities shall be carefully removed and smoothened off . All heads of screws and nails are to be set 1/8” ( or 3 mm) below the surface.

ii) For new Iron and steel work : The surface shall be thoroughly scraped, well brushed and cleaned free of rust, scale, dirt, grease etc. When a priming coat is specified it shall be of red lead and boiled linseed oil unless otherwise specified. Primer coats shall be applied without any time lag after the pre-cleaning and care shall be taken that paint is not applied to a damp surface.


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Application of Paint :

No paint shall be applied until the items of painting have been passed by the Engineer-in-Charge. Surface of all description to be painted shall be thoroughly dry before application of paint. Paint brush shall be of the best quality and skilled painters shall be employed on painting, varnishing etc. Application of the paint shall be done in the manner specified by the manufacturers of paint. The paint shall be laid on evenly and properly by means of crossing and laying off the later in the direction of the grain for woodwork and care shall be taken that the paint is of such consistency that it runs easily from brush. If a skin has formed on the top of the paint, it shall be carefully removed before paint is used. Successive coats of colour shall be applied after the previous coats are thoroughly dried and inspected by the Engineer-in-Charge. Each coat, except the last coat, shall be slightly rubbed down with sandpaper or fine pumice stone and cleaned off dust before the next coat is laid. No hair marks from the brush or clogging of paint shall be left on the work or in the corners of panels, angles of mouldings etc.

Surface Finish :

All painting and varnishing shall be neatly finished and the final surface after painting shall be absolutely uniform in colour and shade and free from brush marks, and without bristles, dirt etc. sticking to the surface. The contractor shall be held responsible for any damage done by dropping or smearing paint or varnish, where it is not required, and shall make good the same. Superfluous patches or stains of paint of varnish may be removed by means of methylated spirit. Contractor’s rate shall include all the materials and labour involved for execution of the work as specified.

H. MISCELLANEOUS WORKS :

H.01 Dismantling & Demolition : The building and other structures including switchyard structures, tower members, rail poles, etc. to be dismantled should be brought down carefully from top to bottom including foundations where required. Dismantling shall be commenced in a systematic manner. All materials which are likely to be damaged by dropping from a height or demolishing roofs, masonry etc. shall be carefully dismantled first. The dismantled articles shall remain as DVC’s property and should be stacked as directed by the Engineer. All unserviceable materials, rubbish etc. shall be disposed off to a place as directed by the Engineer-in-Charge.

Measurement of all work shall be taken before dismantling and no allowance for increase in bulk shall be allowed. Demolition of all types of brick work, cement or lime concrete, reinforced cement concrete etc. below or above ground level shall be measured together in cubic metre without deducting opening for doors, windows etc. No separate measurement and payment shall be made for dismantled doors, windows, pipes and any other wood, steel and iron work etc. Dismantling of all types switchyard structures, tower members, rail poles, etc. below or above ground level shall be measured together in metric tonne.

H.02 Rail Fixing In Concrete : The rail Section shall be fixed to concrete foundation or embedded in concrete


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true to the alignment and levels and as per standards and direction with Contractor’s labour, tools and tackles etc. The rail section shall be supplied to the Contractor at free of cost from DVC Store. Handling, transporting, cutting / shaping to suitable length & shapes of rails shall be done by the Contractor at his cost. The Contractor shall supply, fabricate and erect the required fixture like bolts, plates, tie rods, separators, fish plates etc. as directed by the Engineer to fix the Rails Section in / on concrete.

H.03 Barbed Wire Fencing : Barbed Wire :

The barbed wire shall be of galvanised steel and it shall generally conform to IS : 278-Type-I The barbed wire shall be formed by twisting together two line wires of nominal diameter 2.50 mm one containing the barbs. The barbs shall carry four points and shall be formed by twisting two point wires of nominal diameter 2.24 mm.

Fixing of Barbed Wire :

The barbed wire shall be stretched and fixed in number of rows as specified. Galvanised Turn & buckles and straining bolts shall be used at end posts.

Measurement and Rates :

Barbed wire fencing shall be measured correct to a centimetre for the finished work in metres per line of barbed wire. Rate shall include the cost of all labour and materials involved in all the operations including the cost of galvanised turn buckles and straining bolts and other fixtures and excluding the cost of posts, struts, excavation and concrete in foundation which shall be measured and paid separately under respective items.

H.04 Chain Link Fencing : Scope :

This specification specifies the requirements of chain link fencing for security purposes. The height of the fence shall be approximately 2.0 m. The material requirements shall conform to IS : 2721 (latest) for chain link fence except for requirement which are as given below :

Materials : Posts and Struts :

Straining posts, intermediate posts and struts shall be of Painted M.S. Angles. The posts, intermediate posts, struts, vertical & horizontal flats shall be paid separately as per the relevant item. However the chain link fencing item shall include any fasteners required for erection.

Erection :

Straining posts shall be provided at all ends and corners of fences, at changes in direction of acute variations in level and at intervals not exceeding 66 m on straight lengths of fence. Intermediate posts shall be spaced at regular intervals not exceeding 3.0 m. Struts shall be fitted to all straining posts behind the chain link fabric in the direction of the line of fence.

Fixing :

The chain link fencing shall be strained between each pair of straining posts and secured to each straining post by means of a stretcher bar.


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H.05 Gravel ( Pebbles ) Filling : The gravel ( pebbles ) shall be clean, hard, durable, free from clay, moorum, dirt leaves, any organic matters or admixture of soft or any other foreign materials and shall be of standard approved quality and as suggested / approved by the Engineer-in-Charge. The pebbles/crushed stone must be uniformity graded any thoroughly washed.

The contractor shall prepare site surfacing to the lines and grades in accordance with the requirements and direction of the Engineer-in-Charge. The soil of the entire switch yard area shall be subjected sterilization / antiweed treatment before placing the site surfacing pebbles / crushed stone fill material or strictly as per instruction / required for soil sterilization / antiweed treatment. Anti weed treatment shall be done as per separate approved item and shall be paid separately. After antiweed treatment is complete, the surface of the switchyard area shall be maintained, suitably rolled / compacted to the lines and grades as decided by Engineer-in-Charge. The sub grade shall be saturated with suitable water sprinkling arrangement. The surface shall be compacted by ½ tone roller with minimum 4 to 5 passes. Compacting of the sub grade shall be continued till the soil is evenly and densely consolidated and behaves as an elastic mass. In area that are considered by the Engineer-in-Charge to be too congested with foundations and structures for proper rolling of the site surfacing material by normal rolling equipments, the material shall be compacted by hand, if necessary. Due care shall be exercised so as not to damage any foundation structures or equipment during rolling/compaction. Over the prepared sub grade, 75 thick base layer of cement concrete in 1:5:10 (1 cement : 5 fine sand : 10 burnt brick aggregate) shall be provided in the area excluding roads, drains, cable trenches as per detailed Engineering drawing / site requirement. The area wherever foundation / structure / drain / road / cable trenches / building etc. are coming, shall not have anti-weed treatment & gravel ( pebbles ) filling. For easy drainage of water, a slope of 1:1000 is to be provided from the ridge to be nearest drain. The ridge shall be suitably located at the centre of the area between the nearest drain. The above slope shall be provided at the top of base layer of cement concrete (1:5:10) . A layer of cement slurry of mix 1:6 (1 cement : 6 fine sand) shall be laid uniformly over cement concrete layer. The cement consumption for cement slurry shall not be less than 150 Kg per 100 sqm. A final layer of 75 mm thickness of gravel (pebbles/crushed stone) of 40 mm normal size (ungraded size) shall be spread uniformly over cement concrete layer after curing is complete. The work should be taken up preferably after monsoon.

N.B. If any item of work is not available in the Schedule of Works of Agreement, the item shall be derived from the similar item of CPWD, DSR-2007. This Specification for General Civil Works shall be read along with Schedule of Rates for Civil Works. However, in all practical purposes the description of any item in the Schedule of Rates for Civil Works will be prevalent. For any discrepancies regarding Specification for General Civil Works reference may be made to CPWD Specification for Civil Works.


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GENERAL SPECIFICATION FOR CIVIL,

STRUCTURAL, ARCHITECTURAL WORKS

SECTION – I

GENERAL

1.00.00 INTRODUCTION

The Volume of this specification cover site survey, soil investigation, site

development works, design and construction of Civil, Structural and

Architectural works associated with substation Turnkey Package. The

scope of works covers complete Civil, Structural and Architectural Works

including supply of all materials labour tools and plants as required for

successful execution of the turnkey package.

This section – I lists Codes and Standards to be adopted and the

principal structures of the Sub-station and briefly describes the basic

concept, requirements and features pertinent to each. Documents to be

submitted have also been brought out in this section along with the

procedure to be followed for the same.

2.00.00 CODES AND STANDARDS

Following is a general listing of Codes and Standards to be used in the

design of the substation. Specific applicable codes and standards will be

identified in System Design Descriptions/Technical Specifications as

appropriate. The latest editions/revision of following codes and

standards along with addendums/amendments, if any, shall be followed.

2.01.00 General

a) Internationally accepted design Codes and Standards where

Indian Codes are not available and which are equivalent to

Indian Standards.

b) National Building Code of India.

c) “Accepted Standards” and “Good Practice” listed in the appendix

to National Building Code of India.

d) IS-200 : Method of measurement of Building and Civil

Engineering Works.

e) IS-1256 : Code of Practice for Building Byelaws.

2.01.01 Earthwork

a) IS-1498 : Classification and identification of soils for

General Engineering purposes.

b) IS-3764 : Safety Code for excavation work.

c) IS-7293 : Safety Code for working with construction


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machinery

2.01.02 Concrete

a) IS-269 : Ordinary and low heat Portland cement.

b) IS – 383 : Coarse and fine aggregate from natural sources for

concrete.

c) IS-432 : Mild Steel and medium tensile steel bars and hard

drawn steel wire for concrete reinforcement.

d) IS -455 : Portland Slag Cement.

e) IS-456 : Code of Practice for Plain and reinforced concrete.

f) IS-460 : Test Sieves (all parts).

g) IS – 516 : Methods of test for strength of concrete.

h) IS-1199 : Methods of sampling and analysis of concrete.

i) IS-4566 : Hard drawn steel wire fabric for concrete

Reinforcement.

j) IS-1786 : High strength deformed steel bars and wires for

concrete reinforcement.

k) IS-1834 : Hot applied sealing compounds for joints in

concrete.

l) IS-2386 : Methods of test for aggregates for concrete (all

parts)

m) IS-2502 : Code of practice for bending and fixing of bars for

concrete reinforcement.

n) IS-3370 : Code of practice for concrete structures for storage

of liquids (all parts).

o) IS-3414 : Code of practice for design and installation of

joints in buildings.

p) IS-4948 : Welded steel wire fabrics for general use.

q) IS-6452 : High Alumina Cement for Structure use.

r) IS-7320 : Concrete slump test apparatus.

s) IS-7861 : Code of practice for extreme weather concreting

(all parts).

t) IS-8041 : Rapid Hardening Portland Cement.

2.01.03 Foundations

a) IS-1904 : Code of practice for structural safety of buildings :

Shallow foundations.

b) IS-2950 : Code of practice for design and construction of raft

foundations.


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2.01.04 Loading

a) IS-875 : Code of practice for Structural safety of building

loading standards.

2.01.05 Masonry

a) IS-712 : Building limes.

b) IS-1077 : Common Burnt Clary Building Bricks.

c) IS-1127 : Recommendations for dimensions and

workmanship

of natural building stones for masonry work.

d) IS-1528 : Methods of sampling and physical tests for

refractory materials.

e) IS-1597 : Code of practice for construction of stone masonry

(all parts).

f) IS-2212 : Code of practice for brickwork.

g) IS-2116 : Sand for masonry mortars.

h) IS-2185 : Concrete masonry units.

(all parts – Hollow and Solid concrete blocks)

i) IS-2250 : Code of practice for preparation and use of

masonry mortars.

j) IS-2572 : Code of practice for construction of hollow

concrete block masonry .

k) IS-2691 : Burnt clay facing bricks.

l) IS-3414 : Code of practice for design and installation of

joints in buildings.

m) IS-3495 : Methods of tests of burnt clay building bricks.

n) IS-4441 : Code of practice for use of Silicate type chemical

resistant mortars.

o) IS-4860 : Acid Resistant Bricks.

2.01.06 Doors, Windows and Ventilators

a) IS-399 : Classification of commercial timbers and their

zonal distribution.

b) IS-883 : Code of practice for design of structural timber in

building.

c) IS-1003 : Timber paneled and glazed shutters (all parts)

d) IS-1038 : Steel doors, windows and ventilators.

d) IS-1081 : Code of practice fox fixing and glazing of metal

(steel and aluminium) doors, windows and

ventilators.


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f) IS-1361 : Steel windows for industrial buildings.

g) IS-2835 : Transparent sheet glass for glazing and framing

purposes.

h) IS-1948 : Aluminium doors windows and ventilators.

i) IS-1949 : Aluminium windows for industrial building.

j) IS-2191 : Wooden flush door shutters (Cellular and hollow

core type)

k) IS-2202 : Wooden flush door shutters (solid core type)

l) IS-3103 : Code of practice for Industrial ventilation.

m) IS-3548 : Code of practice for glazing in buildings.

n) IS-3614 : Timber door, windows and ventilator frames.

p) IS-4351 : Steel door frames.

q) IS-6248 : Metal rolling shutters and rolling grills.

2.01.07 Roof and Flooring

a) IS-2204 : Code of practice for construction of reinforced

concrete shall roof.

b) IS-3201 : Criteria for the design and construction of precast

concrete trusses.

c) IS-2210 : Criteria for Design of R.C. shall structures and

folded plates.

d) IS-809 : Rubber flooring materials for general purposes.

e) IS-1196 : Bitumen mastic for flooring.

f) IS-1198 : Code of practice for laying, fixing and maintenance

of linoleum floors.

h) IS-1237 : Cement concrete flooring tiles.

i) IS-1443 : Code of practice for laying and finishing of cement

concrete flooring tiles.

j) IS-2114 : Code of practice for laying in situ terrazzo floor

finish.

k) IS-2571 : Code of practice for laying in situ cement concrete

flooring

l) IS-5491 : Code of practice for laying in situe granolithic

concrete floor topping.

m) IS-5766 : Code of practice for laying burnet clay brick

flooring

n) IS-1197 : Code of practice for laying of rubber floors.

o) IS-2441 : Code of practice for fixing ceiling coverings.


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2.01.08 Waterproofing

a) IS-1322 : Bitumen felts for waterproofing and damp

proofing.

b) IS-1346 : Code of practice for waterproofing of roofs

with bitumen felts.

c) IS-1609 : Code of practice for laying damp proof treatment

using bituminous felts.

d) IS-3036 : Code of practice for laying lime concrete for a

waterproofed roof finish.

e) IS-3037 : Bitumen mastic for use in waterproofing or roofs.

f) IS-3067 : Code of practice for general design, details and

preparatory work for damp proofing and water

proofing of buildings.

g) IS-3384 : Bitumen primer for use in water proofing and

damp proofing.

h)IS-4365 : Code of practice for application of bitumen mastic

for waterproofing of roofs.

2.01.09 Soil Engineering

a) IS-1498 : Classification and identification of soil for

general engineering purpose.

b) IS-1892 : Code of practice for sub-surface investigation for

foundation.

c) IS-2131 : Method for standard penetration test for soils.

d) IS-2720 : Methods of test for soils (all parts)

2.01.10 Water Supply, Drainage and Sewerage

a) IS-404 : Lead pipes

b) IS-458 : Concrete pipes

c) IS-651 : Salt glazed stoneware pipes and fittings.

d) IS-771 : Glazed fire-clay sanitary appliances (all parts).

e) IS-774 : Flushing cisterns for water closets and urinals

other than plastic cisterns.

f) IS-783 : Code of practice for laying of concrete pipes.

g) IS-1172 : Code of basic requirements for water supply,

drainage and sanitation.

h) IS-1626 : Asbestos cement building pipes, gutters and

fittings (all parts).

i) IS-1742 : Code of practice for building drainage.

j) IS-2064 : Code of practice for selection, installation and


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maintenance of sanitary appliances.

k) IS-2065 : Code of practice for water supply in buildings.

l) IS-2470 : Code of practice for installation of septic tanks

(all parts).

m) IS-3114 : Code of practice for laying of cost Iron pipes.

n) IS-4127 : Code of practice for laying of glazed stoneware

pipes.

o) IS-12251 : Code of practice for Drainage of Building

Basement.

p) IS-1200 : Method of measurement : Laying of water and

[Part-XVI] sewer lines including appurtenant

items.

q) IS-3486 : Cast iron spigot and socket drain pipes.

r) IS-5329 : Code of practice for sanitary pipe work above

ground for buildings.

s) IS-3076 : Low density polyethylene pipes for potable water

supplies.

t) IS-1538 : Cast iron fittings for pressure pipes for water,

gas and sewage.

u) IS-1230 : Cast iron rainwater pipes and fittings.

v) IS-1729 : Sand cast iron spigot and socket soil, waste and

ventilating pipes, fittings and accessories.

w) IS-1726 : Cast iron manhole covers and frames.

aa) IS-5961 : Cast iron grating for drainage purposes.

bb) IS-5219

[Part-I]

: “P” and “S” traps.

cc) IS-772 : General requirements for enameled cast iron

sanitary appliances.

dd) IS-775 : Cast iron brackets and supports for wash

basins and sinks.

ee) IS-777 : Glazed earthenware wall tiles.

ff) IS-2548 : Plastic water closet seats and covers (all parts).

gg) IS-2527 : Code of practice for fixing rainwater gutters and

downpipes for roof drainage.

2.01.11 Paving and Road work

a) IS-73 : Paving bitumen

b) IS-702 : Industrial Bitumen

c) IS-1201 : Method of testing tar and bituminous materials


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thru 1220.

d) Practice followed by Indian Road Congress (all parts).

2.01.12 Earthquake Resistant Design

a)IS-1893 : Criteria for earthquake resistant design of

structures.

b) IS-4326 : Code of practice for earthquake resistant design

and construction of building.

2.01.13 Structural Steelwork

a) IS-800 : Code of practice for general construction in

steel.

b) IS-802 : Code of practice for use of structural steel in

Overhead Transmission Line.

Part – I : Load and permissible stresses.

Part – II : Fabrication, Galvanising, Inspection

and Packing.

c) IS-808 : Rolled steel beams, channels and angle

sections.

d) IS-813 : Scheme of symbols for welding.

e) IS-814 : Covered electrodes for manual metal arc welding

of carbon and carbon manganese steel.

f) IS-816 : Code of practice for use of metal arc welding for

general construction in mild steel.

g) IS-817 : Code of practice for training and testing of metal

arc welders.

h) IS-818 : Code of practice for safety and health

requirements in electric and gas welding and

cutting operation.

i) IS-819 : Code of practice for Resistance spot welding for

light assemblies in Mild Steel.

j) IS-919 : Recommendations for limits and fits for

engineering

k) IS-1200

[Part – VIII]

: Method of measurement of steelwork and

ironwork.

l) IS-1239 : Mild steel tubes, tubular and other wrought

steel fittings (all parts).

m) IS-1363 : Black hexagonal bolts, nuts and locknuts (dia. 6

to 39 mm) and black hexagon screws (dia. 6 to

24 mm) [all parts].


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n) IS-1364 : Precision and semi-precision hexagon bolts,

screws, nuts and locknuts (dia. Range 6 to 39

mm) [all parts]

o) IS-1365 : Slotted counter sunk head screws (dia range 1.6

to 20 mm)

p) IS-1367 : Technical supply conditions for threaded steel

fasteners.

q) IS-1443 : Code of practice for laying and finishing of

cement concrete flooring tiles.

r) IS-1608 : Method for tensile testing of steel products .

s) IS-1730 : Dimensions for steel plate, sheet and strip for

structural and general engineering purpose.

t) IS-1731 : Dimensions for steel flats for structural and

general engineering purposes.

u) IS-1852 : Rolling and cutting tolerances for hot rolled steel

products.

v) IS-1977 : Structural steel (Ordinary quality)

aa) IS-2016 : Plain Washers.

bb) IS-2062 : Steel for General structural purposes.

cc) IS-2074 : Ready mixed paint, air drying, red oxide zinc-

chrome, priming.

dd) IS-2633 : Methods of testing uniformity of coating of zinc

coated articles.

ee) IS-3757 : High strength structural bolts.

ff) IS-4000 : High strength bolts in steel structures.

gg) IS-4759 : Hot dip zinc coatings on structural steel and

other allied products.

hh) IS-7215 : Tolerances for fabrication of steel structures.

ii) IS-7318

[Part – I]

: Approval tests for welders when welding

procedure approval is not required.

jj) AWSD1.1 Structural Welding Code.

2.01.14 Painting

a) IS-348 : Specification for French Polish

b) IS-427 : Specification for Distemper, dry colour as

required.

c) IS-428 : Specification for Distemper, oil emulsion, colour

as required.

d) IS-1477 : Code of practice for painting of ferrous metal in


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[I & II] buildings.

e) IS-2338

[I & II)

: Code of practice for finishing of wood and wood

based materials.

f) IS-2339 : Specification for Aluminium Paints for general

purposes in dual containers.

g) IS-2395 : Code of practice for painting concrete, masonry

and plaster surface.

h) IS-2932 : Specification for enamel, synthetic, exterior – a)

undercoating, b) finishing.

h) IS-2933 : Specification for enamel, exterior – a)

undercoating, b) finishing.

i) IS-5410 : Specification for cement paint.

2.01.15 Environmental Protection :

Charter on Corporate Responsibility for Environmental Protection

(CREP) published in Gazette of India dated 27.08.2003.

3.00.00 SCOPE OF CIVIL WORKS

The scope of civil work comprises all necessary investigations

survey/foundations, building, superstructures and infrastructure

required for the complete operating power station.

The work under this Section consists of Civil, Structural and

Architectural works, but not limited to items mentioned below.

- Area Grading, leveling & dressing.

- Soil investigation

- Demolition and site clearance including tree cutting

- Plant Boundary Wall as per Plot Plan

- Temporary fencing between facilities of existing units & proposed

area.

- In Substation Road connecting the road network of the existing

Substation (as marked in Plot Plan) and access road from adjacent

Public Road/Highway outside Boundary.

- Drainage network (as marked in Plot Plan) and terminating the same

upto the outfall location identified in the Plot Plan.

- Transformer yard including transformer foundations, Fire walls, Rail

track etc.

- Electrical Grounding mat

- Cable/pipe racks.


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- 220 KV Substation structures & foundations, switchyard control

buildings.

- All other civil items not covered above but required for completion

and proper functioning of the plant shall from part of the scope.

- Architectural finishing including flooring, paving, Side cladding with

or sheeting brick masonry, walls, plastering, painting, false ceiling

doors & windows, plumbing, roof treatment etc. for buildings.

The scope shall also in include setting up by the Contractor a complete testing

laboratory in the filed to carry out all relevant tests required for the civil works for the

project.

Water will be supplied by the Owner free of charge at a mutually agreed single point

within the battery limit of existing plant & the Bidder shall arrange distribution of the

same beyond the above point at their own cost.

A list of Civil-Field Quality Assurance Laboratory Apparatus is enclosed in Annexure –

II of the Section.

The Bidder shall visit the site and assess the involvement of demolition and site

clearance, if required, within the area to construct the project & accordingly the costs

is to be considered in his offer.

The work shall have to be carried out both below and above the ground level. The work

shall be executed accordance to the relevant Indian Standard Code, and in its absence

the work shall be executed according to the best prevailing local Public Work

Department (PWD) practices or to the recommendations of relevant American and

British Standards or to the instructions of the Owner’s Engineer. This shall prevail in

respect of civil works for which no specification has been prescribed in this section.

The work shall be carried out according to the design/drawings to be developed by the

Contractor and approved by the Owner/Owner’s authorised Consultant. For all

building structures, foundations etc., necessary terraced layout and details are to be

developed by the Contractor eping in view the statutory & functional requirement of

the plant & facilities and providing enough space & access for operation, use and

maintenance.

The land will be given to the Contractor by the Owner as is where basis. All site

investigations, surveys, grading and levelling and other additional works shall be

carried out by the Contractor.

The layout and levels of all structures shall be made by the Contractor at his own cost

from the general grid of the plot and the nearest GSI bench mark or other acceptable

bench mark of Govt. Dept. The Contractor shall be solely responsible for the

correctness of the layout and levels.

All necessary statutory clearances shall be obtained by the Bidder prior to execution of


77

work under scope of this specification.

All the quality standard, tolerances, welding standards and other technical

requirements shall be strictly adhered to by the Contractor.

4.0.00A. Substation

Substation structures comprise of all towers, gantries, lighting towers,

lightning towers/masts, chain link fencing with gates, equipment

supports and other structure – all of galvanized steel and with bolted

type joints. Foundations for above structures will be reinforced cement

concrete. Cable trenches with precast RCC covers of removable type,

sump pits, oil pits, cable tray supports, grounding etc. will be

constructed in Switchyard areas. Foundations for jacking transformers,

oil drainage piping etc. will also be provided. Baffle walls shall be

arranged based on layout of transformers and statutory requirement.

Additional protection for buried cables need be provided under

road/railway track in form of RCC/galvanized iron pipes/RCC box

culvert.

Lighting towers shall be provided with a structural steel ladder from its

base upto the top of tower. The ladder shall be provided with protection

guards in the form of rings. Platform (having a maximum spacing of 10

meters) with protection hand-railing shall be provided at suitable heights

for mounting of lighting fixtures.

4.0.00B Roads

Main access to the Sub-station shall be from adjacent Public

Road/Highway. All substation service roads 4 M/6 M wide, water bound

macadam with bituminous topping on prepared sub grade for heavy

vehicles, providing access to all truck sized building doors and all

structures requiring maintenance by vehicles. Water bound macadam

with bituminous topping will be provided at areas requiring parking

areas shall be done after completion of substation construction.

Substation roads under scope of this package shall be connected to the

existing roads of the substation for smooth movement of internal traffic.

Peripheral road around Boundary wall (Inside), are also within the

scope of this contract.

All Roads shall be designed in accordance with the provision of the

latest edition of the relevant I.R.C. codes of practice.

The subgrade shall be prepared with well compacted selected

soil/earth. Subbase shall be 225 mm thick (consolidated thickness)

grannular subbase with crushed stone (grading-1), morum and sand.


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Seal coat shall be 25 mm thick. The wearing coarse shall be 75 mm

thick bitumen concrete binder course with 25 mm open graded premix

carpet, laid on 225 mm thick (compacted thickness) water bound

macadam course.

4.0.00C Transformer Areas and Switchyard

Oil cooled equipment, such as transformers, will be located within

concrete basins filled with gravel. The individual basins will be

connected by pipeline to a separate chamber/oil pit for collection and

further reclamation of oil through oil water separators, if necessary

Drains will be adequate to remove full discharge from deluge system

used for fire control. Transformer Yard will be paved with reinforced

cement concrete. Switchyard area shall be filled with 150 mm thick

concrete (M10)

4.0.00D Drainage System

Yard drainage system shall be designed in two parts :

i) in Drains

ii) Auxiliary Drains

Main drains, Metro drains shall be designed as a network covering plant

area within the battery-limit of this specification. This plant area

drainage has to be terminated at the outfall location shown in the Plot

Plan. Attempts will be made to convert construction drains into main

drain as far as practicable. Auxiliary/Branch drains shall cover

individual grades to terrains, collect storm water and other non-

contaminated discharge from plant buildings and then be connected to

Main drain at suitable locations. The invert of the in-plant peripheral

drains shall be kept such that water can be discharged by gravity to the

main/trunk drain under all condition. RCC pipe culverts/box culverts

will carry drainage under interrupting roads and railway tracks.

Effluent drains shall completely be separated from storm water drainage

and not within the Scope of this contract. Suitably designed

underground storm water RCC piping on the basis of design loads

specified elsewhere in this specification shall be limited to required

areas where surface drainage ways are not desirable or practicable from

other functional point of view. Class of RCC pipes shall be decided by

Bidder as per design requirement. For pipe drains, concrete pipes of

minimum grade – Class NP2 will be used. However, for road concrete

pipes of Class NP3 will be used R.C.C. Manholes will be provided at

maximum 30 m intervals along the length, at connection points and


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every change of alignment, gradient or diameter of pipeline. The drains

shall generally be of open type RCC rectangular construction with RCC

pre-cast cover. R.C.C. (M-20) perforated precast cover of minimum

thickness 75mm with provision of openable G.I. grating cover at about

4.0 m interval. Thickness of G.I. grating over drain shall be 40 m and 32

mm for inside building and outside area (without vehicular movement

and equipment load) respectively. The storm water drainage shall also

cater for discharge of treated waste water. The drainage system shall be

designed for precipitation intensity of 75 mm per hour (maximum

hourly intensity of rainfall).

Surface drains will normally have a slope of 1 IN 1000 along

longitudinal direction and RCC pipes to have such slops such as to

have effective discharge. RCC or masonry structures will be provided at

drops/falls to prevent scouring. Minimum self-cleansing velocity should

be adopted as 0.8 m/sec.

4.0.00E. Sanitary Sewerage System :

For sewage treatment, adequate number of septic tanks will be installed

and the effluent shall be discharged Soak Pit.

5.0.00 A DOCUMENT SUBMISSION

Design and Construction documents pertaining to all Civil. Structural

and Architectural works that will be required to be submitted to

Owner/Owner’s Consultant/Review Consultant for their approval have

been brought out under following clauses. Approval of these documents

by the Owner/Consultant shall not relieve the Contractor of his

responsibility for any errors and fulfillment of Contract requirements.

5.0.00B. Design Document

Design Document shall comprise Electrical assignment Drawings, design

data, design assumptions & references, detailed structural analysis

(including computer out put, if any) & design calculations and design

drawings.

Design calculations and drawings shall be submitted and reviewed only

after approval of corresponding Electrical/System general arrangement

drawings. The contractor shall submit approved GA drawings along with

three (3) copies of design documents (except design drawings) and eight

(8) copies of design drawings for comments/ approval of the

Owner/Consultants. Soft/electronic copy of 2D and 3D analysis file and

drawing shall be submitted with first submission. Contractor shall


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submit three (3) copies of design calculation and twelve (12) copies of the

drawing with one soft copy in CD each to the Owner and consultant for

distribution.

5.0.00C. Construction Document

Based on approved design drawing, detailed drawings for construction

will be prepared by the Contractor. For reinforced concrete structures

and foundations detailed bar bending schedules in approved format

shall accompany each detailed drawing . For structural steel work the

Contractor will prepare detailed fabrication drawing along with bill of

materials.

Six (6) copies each of selected or all detailed drawings/fabrication

drawings as decided by Engineer for all structures along with bar

bending schedule/bill of materials need be furnished to

Owner/Consultants for their review and approval.

5.0.00D. As Built Drawings

“As-built” drawings shall be prepared by the Contractor after completion

of construction/erection incorporating all the changes, if any, done on

Engineer'’ instruction/approval. After completion of construction,

Contractor shall submit eight (8) copies of the all drawings, irrespective

of any changes during construction, market “As Built” with one soft copy

in CD each to the Owner.

6.0.00 LAYOUT

Before starting the work, the Contractor shall carry out the setting out of

foundation and structures and provided levels, with reference to general

existing grid and bench mark. If the Contractor uses the grid, bench

mark and reference pillar made by other Contractors, he shall co-

ordinate with the Contractor and shall satisfy himself of the accuracy of

the reference marks. If he is required to set out the foundation afresh, he

shall do so independently with reference to the one existing grid and

bench mark which has been followed by other agency at the instruction

of the Engineer. In case any discrepancy be found, it shall be

immediately brought to the notice of the Engineer for any

rectification/modification necessary. No complaint shall be entertained

at a later stage. The Contractor shall accurately set out the position for

holding down bolts and inserts.

If required, in the option of the Engineer, he shall construct and

maintain pillars for grid, references and bench marks and maintain


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them till the completion of the construction. He shall also help the

Engineer with instruments, materials and labours for checking the

detailed layouts and levels. The Contractor shall be solely responsible for

the correctness of the layout and levels, and Engineer’s approval shall

not be deemed to imply any warranty in carrying out the works correctly.

The Tenderers shall take into account the cost of these in quoting their

price.

7.0.00 WORKMANSHIP

Workmanship shall be of the best possible quality and all work shall be

carried out by skilled workmen except for those which normally require

unskilled persons. Welding shall be done by experienced and certified

welders in proper sequence using necessary jigs and fixtures.

Fabrication shall be done in shops having proper equipment for accurate

edge – lanning and milling of column shaft ends, base plate surfaces etc.

and shaping and dimensioning of anchor bolt assembly, inserts and

other misc. items. In addition to the requirement specified above, if the

bye-laws of the local Govt. Municipal or other authorities require the

employment of licensed or registered workmen for various trades, the

Contractor shall arrange to have the work done by such registered or

licensed personnel. In case of manufactured materials, the Contractor

shall have, with no additional cost to the Owner, the services of the

supervisors of the manufacturers to ensure that the work is being done

according to the manufacturer’s specifications.

8.0.00 TEMPORARY WORK

All scaffoldings, staging, temporary bracing and other necessary

temporary work required for proper execution of the Contract shall be

provided by the Contractor at his own cost and inclusive of all materials,

labour, supervision and other facilities.

The layout and details of such Temporary work shall have the prior

approval of the Engineer but the Contractor shall be responsible for

proper strength and safety of the same. All Temporary work shall be so

constructed as not to interfere with any permanent work shall be so

constructed as not to interfere with any permanent work or with the

work by other agencies. If it is necessary to remove any of the temporary

work at any time to facilitate execution of the work or with the work of

other agencies such removal and re-erection, if required, shall be carried

out by the Contractor at the direction of the Engineer without any delay


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and any extra cost on this account shall be borne by the Contractor.

9.0.00 SEQUENCE OF WORK AND PROGRESS REPORT

The sequence in which the work s are to be carried out shall be as

approved by the Engineer in accordance with the construction method

accepted by the Engineer and to be followed by the Contractor. A

programme of work is to be submitted for the Engineer’s review and

approval and this has to be periodically updated and modified as per

actual to enable timely completion.

The Contractor shall regularly submit to the Engineer progress reports

for periods of working as specified by the Engineer showing upto date

progress on all important items of work.

10.0.00 DESIGN CONSIDERATION FOR

a) Switchyard Structures

Gantry structures consist of open web towers connected by girders.

These shall be made of structural steel conforming to IS : 2062 Grade

and duly galvanized conforming to IS : 2629. All joints shall be bolted

connections. All bolts shall be 16 mm dia conforming to IS : 12427 of

property class 5.6 conforming to IS : 1367 (Part 6) : 1980. Nuts shall

conform to I.S. 1363 (Part 3) : 1992 of property class 5. But splice is

used for splicing the main members and splice shall be located away

from the node point. IS : 802 “Code of practice for use of structural steel

in overhead transmission line towers” shall be followed for design of

structural supports & IS : 875 (Part – II) shall be followed for wind force

calculation. Height & type of towers shall be established based on

electrical requirements.

Switchyard structures shall be designed for the worst combination

following loads :

1) Dead loads (load of wires/conductors, insulator, electrical equipment’s

and structural members),

2) Live loads.

3) Wind load on bus bars, shield, wires, insulator strings, electrical

equipment, structural members etc as per IS : 802.

4) Seismic loads.

5) Temperature load.

6) Loads due to deviation of conductor (gantries shall be checked for + 30

deg. deviation in horizontal plane and + 20 degree deviation in vertical

plane).


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7) Loads due to unbalanced tension in conductor/wire.

8) Torsional load due to unbalanced and horizontal forces.

9) Erection loads.

10) Short circuit forces including snap in case of bundled conductors, etc.

Note :

i) The occurrence of earthquake and maximum wind pressure is unlikely

to take place at the same time. The structure shall be designed for either

of the two. However, temperature stresses can be ignored, as these

towers are freestanding structure in open space.

ii) Direction of wind shall be assumed such as to produce maximum

stresses in any member for the combination of wind load with conductor

tensions. The wind acting perpendicular and parallel to bus conductor

and shield wire shall be considered separately.

iii) The conductor tension shall be assumed as acting on only one side of

the gantry for the analysis and design of switchyard gantries.

iv) The distance between terminal and dead end gantry shall be taken as

200 meters.

Factor of safety :

The factor of safety for the design of members shall be considered as 2.0 for

normal condition and broken wire condition, 1.5 for combined short circuit and

broken wire condition. Foundation shall be designed for a factor of safety of 2.2

for normal and broken wire condition and 1.65 for combined short circuit and

broken wire condition.

b) Design consideration for Equipment support :

The supporting structure for B.P.I., LA, CVT & Isolator equipment’s shall be

comprised of GI (ERW) pipe of grade YST : 210 or of higher grade conforming to

IS : 1161 & shall be designed as per IS : 806 “Code of Practice for use of steel

tubes in general building construction”.

The supporting structure for CT & Wave Trap equipment shall be comprised of

lattice structural steel conforming to IS 2006 and shall be designed as per IS :

802.

c) Special design consideration for lighting Mast :

Diagonal wind condition shall be considered for lightning masts. Provision of IS

: 875 (Part – III) – 1987 shall apply for inclined wind condition. Lightning mass

shall be provided with minimum two nos. of platforms (with 1 at top level) and

an internal ladder for climbing purpose up to platform at top level. Top of

platform shall have grating, railing and two guard plates.


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The fabrication and erection of the switchyard works shall be carried out

generally in accordance with IS : 802 and IS : 800. All materials shall be

completely shop fabricated and galvanised.

All steel work used in construction of gantry structure should be galvanized and

minimum section thickness should not be less than 4 mm. Weight of zinc

coating shall be at lest 0.610 kg/m2 and foundation bolts shall have heavier

zinc coating at least 0.80 kg/m2.

d) SWITCHYARD CONTROL ROOM BUILDING

Design considerations and loading considerations for R.C.C. switchyard control

room building shall be considered as specified elsewhere in the specification.

Foundation for all tanks shall be designed for as per I S : 803

Footings shall be so proportioned to as to minimise the differential settlement.

Joints/Connections in steel structures :

Steel structures shall be detailed and connection and joints provided as per the

provisions of IS : 800, IS : 816, IS : 9595, IS : 1367 and IS : 9178 and as per

following requirements.

a) Connection of vertical bracings with connection members and diagonals of trues

members shall be designed for full tensile capacity of the bracings unless actual

loads are indicated on the drawings.

b) Size of fillet weld for flange to web connection for built up section shall be as

follows :

i) For box section weld size shall be designed for full shear capacity or

actual shear whichever is more. Where fillet weld is not possible, full

penetration but weld shall be provided.

ii) For built up I section, weld size shall be designed for 80% of full shear

capacity or actual shear, (if indicated, in drawings) whichever is more.

However, weld size shall not be less than 0.5 times the web thickness.

Weld shall be double fillet.

iii) All welds shall be continuous unless otherwise specifically approved. The

minimum size of the fillet weld shall be 6 mm.

c) Shear connections shall be designed for 60% of section strength for rolled

section and 80% of section strength for built up section or rolled section with

cover plates. However, if load is more than above, the connection shall be

designed for actual load.

d) Moment connections between beam and column shall be designed for 100% of

moment capacity of the beam section. This can achieved either by direct butt


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welding of the top flange of beam with column flange or by providing top

moment plate with suitable notch for additional weld length.

e) All but welds shall be full penetration butt welds.

f) The connection between top flange and web of crane girder shall be full

penetration butt weld. Bottom flange, connection with web can be fillet weld or

butt weld as directed by Engineer.

g) Connection of base plate and associated stiffeners with the columns shall be

designed considering the total load transferred through welds. However,

minimum weld size (double fillet) shall not be less then 0.6 times the thickness

of stiffeners.

h) Splicing : All work shall be full strength. Field splicing shall be done with web

and flange cover plates for full strength. In exceptional cases, the filed splicing

shall be designed for 50% of load carried by the cover plates and remaining 50%

load through full penetration butt weld. Shop splicing for all sections other than

rolled shall be carried out by full penetration butt welds with no cover plates.

Splicing for all rolled sections shall be carried out using web and flange cover

plate.

11.0.00. Corrosion Protection

a) Steel Structure

i) All steel members of buildings and structures shall be provided with

suitable protective coating. The minimum maintenance free life of

protective coating shall be ten years (expected life, long range 10 to 20

years as per BS 5493). For sheltered structures where sides are not fully

covered such as conveyor galleries, deaerator floor, bunker building,

transfer tower etc. both exterior and interior of structure shall be

considered as exposed to non-polluted inland atmosphere condition. For

other structures exterior of the structure shall be considered as exposed

to non-polluted inland atmosphere condition and interior of the

structure shall be considered as normally dry condition . Minimum 75

micron DFT of organic zinc silicate primer shall be applied (over blast

cleaned surface to near white metal conforming to Sa2 ½ finish) on all

exterior and interior surfaces.

Intermediate coat, which shall be applied for all interior and exterior

surfaces shall consist of epoxy, based TIO2 or MIO of minimum 75

micron DFT.

Interior surfaces (considered with normally dry condition) shall be

finished with (minimum 75 micron DFT) chlorinated rubber paint of

approval shade.


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All exterior and interior surfaces (considered as exposed to non-polluted

inland atmosphere condition) shall be finished with (minimum 70

micron DFT) epoxy based paint, which shall be further finished with top

coat of (minimum 30 micron DFT) polyurathane of approved shade.

All paints shall be of high built constitution.

ii) All mild steel parts coming in contact with water or water vapour shall

be hot dip galvanised. The minimum coating of zinc shall be 610

gm/sq.m. for galvanised structures and shall comply with IS : 4759 and

other relevant codes. Galvanising shall be checked and tested in

accordance with IS : 2629.

The galvanising shall be followed by the application of an etching primer

and dipping in black bitumen in accordance with BS : 3416, unless

otherwise specified.

iii) All structural steel members in switchyard (excluding fencing and gate) shall be

hot dip galvanised as specified elsewhere.

b) For reinforced concrete work

i) The protection for concrete sub-structure shall be provided based on

aggressiveness of the soil, chemical analysis of soil/sub-soil water and presence

of harmful chemicals/salts.

ii) The protection to super structure shall depend on exposure condition and

degree of atmospheric corrosion.

This shall require use of dense and durable concrete, control of water cement

ratio, increase in clear cover, use of special type of cement and reinforcement

etc. coating of concrete surface etc.

Bidder shall furnish the details of corrosion protection measures.

12.00.00 GEOTECHNICAL INVESTIGATION AND FOUNDATION SYSTEM.

The Contractor shall carry out detailed geotechnical investigation in all

work areas under his scope for establishing the sub-soil conditions and

to decide type of foundations for the structures envisaged, construction

methods, any special requirements/treatment called for/remedial

measures for sub-soil/foundation etc. for soft-soils, aggressive sub-soils

& water, expansive/swelling soils etc. prior to commencement of detailed

design/drawings. Contractor shall obtain the approval for the field and

laboratory testing scheme proposed by him from the Owner before

undertaking the geotechnical investigation work.

Field test shall include but not be limited to the following :


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Boreholes, Standard Penetration Test (SPT), collection of disturbed and

Undisturbed soil samples (UDS), Trial Pits (TP), Plate load test (PLT),

Dynamic Cone Penetration Test (DCPT), Pressure meter tests (PMT),

Seismic Refraction Test (SRT), Electrical Resistivity Tests (ERT) and

collection of water samples etc.

Scheme of Soil Investigation

The diameter of borehole shall be minimum 150 mm in soil and 76 mm

in rock. The diameter of UDS sampler shall be 90 mm minimum. Drilling

in rock shall be done by means of hydraulic feed equipment using

double tube core barrel with diamond bid attachment.

Filed investigations shall be done as indicated in Annexure – 1 SPT shall

be carried out in all types of soil deposits and in all rock formations with

RQD< 20% within a borehole. This test shall be conducted at every 3.0m

m interval or at change of strata, upto the final depth. Number of blows

shall be recorded for every 15 cm of penetration upto 45 cm or 100

blows whichever occurs earlier. UDS shall be collected at every 3.0 m

interval or at change of strata upto depth of borehole. Depth for DCPT

shall be upto refusal (for DCPT, refusal shall be considered, when the

blow count exceeds 150 for 300 mm penetration). Depth of PLT shall be

at proposed founding level for shallow foundations only.

Laboratory tests shall be carried out on disturbed and undisturbed soil

samples for Grain Size Analysis. Hydrometer Analysis, Atterberg Limits,

Trixial Shear Tests (UU & CD), Natural Moisture Content, Specific

Gravity and Bulk Unit Weight, Consolidation Tests, Unconfined

Compression Test, Free swell Index, Shrinkage Limit6, Swell Pressure

Test, Proctor tests, Chemical Analysis test on soil and water sample to

determine the carbonates, sulphates, chlorides, nitrates, pH, organic

matter and any other chemicals harmful to concrete and

reinforcement/steel.

On completion of all field & laboratory work, contractor shall submit a

Geotechnical investigation report for Owner’s approval. The Geotechnical

investigation report shall contain geological information of the region,

procedure adopted for investigation, field & laboratory observations/data

/ records, analysis of results & recommendations on type of foundation

for different type of structures envisaged for all areas of work.

Recommendations on treatment for soil, foundation, based on subsoil

characteristics, soft soils, aggressive chemicals, expansive soils etc.


88

The report shall also contain recommendations on type of foundations to

be adopted for various structures, duly considering the sub soil

characteristics, water table, total/differential settlement permissible for

structures and equipments, minimum depth and width of foundation

with supporting calculations and design of piles in terms of safe

capacity, length, diameter termination criteria etc.

13.00.00 Foundation System

i) General Requirements :

a) Contractor can either provide open foundations (isolated

footing/raft) or pile foundations depending upon the results of

the geotechnical investigations to be carried out by him.

b) All foundations shall be designed in accordance with provisions

of the relevant parts of the latest revisions of Indian Standards.

c) No major foundation shall rest in the filled up ground/soil.

d) A combination of open and pile foundations shall not be

permitted under the same structure.

e) Foundation shall be designed for worst combination of loads as

described elsewhere in the specification.

ii) Open Foundations

In case open foundations are adopted following shall be adhered to :

a) Minimum width of foundation shall be 1.0 m.

b) Minimum depth of foundation shall be 1.0 m below NGL.

c) Permissible settlement of foundations.

The total permissible settlement and differential settlement shall

be governed by IS : 1904 and IS : 13063 and from functional

requirements, whichever is more stringent. However, total

settlement shall be restricted to the following :

i) All foundations including pipe supports, isolated / strip /

continuous) for widths upto 6.0 m – 40mm

ii) Footings with width greater than 6.0 mm (raft) – 75 mm

iii) Footings resting on weathered rock – 12 mm.