1

<TITLE OF THE PROJECT>

TECHNICAL SPECIFICATIONS FOR ACCESS ROAD AND WELL PAD

(DRAFT)

1. PURPOSE

This technical specification is prepared for construction of access road and well pads for Test Well

Drilling Project for Geothermal Development in Djibouti (hereinafter called as “The Project”), to

drill two (2) geothermal test wells at Hanle Garabbayis area in Dikhil District, Djibouti under

JICA’s technical cooperation.

2. SCOPE OF WORK

This technical specification is limited to access road construction and geothermal well pad

preparation for the Project. The main contents of the work are shown in Table-1;

Table-1 Scope of Work

Contents Work Items

A. Access Road

Construction

A-1 Clarification of Alignment

A-2 Clearing and Grubbing

A-3 Cutting

A-4 Embankment

A-5 Paving of Gravel

A-6 Drainage

B. Base camp and Well Pad

Preparation

B-1 Clarification of Area

B-2 Clearing and Grubbing

B-3 Cutting

B-4 Embankment

B-5 Laying of Gravel

B-6 Construction of Water Pit

B-7 Construction of Sump Pit

B-8 Lining of Water pit and Sump pit

B-9 Concrete Works

B-10 Fencing

2

3. TECHNICAL SPECIFICATIONS

A. Access Road Construction

General

This work shall consist of the excavation/cutting, forming embankment, placement, grading and

compaction of base course material, paving and drainage for access road.

The access road is connected from the national road No.1 to the well pad A-1, A-2, and A-3, with

total length of 4,222m. The road is planned of single track with the nominal width 5 m in principle,

associated with widened double truck stretches (Side lay-by) of the nominal width 8 m for dual

traffic. The side lay-by sections are planned to be constructed approximately on every 500m of

the access road and 50m length each.

The bearing capacity of the access road shall be specified in the standard for the transportation by

20-ton class trailers. The road is normally paved with gravel of 50 cm.

The road was designed concordant with the original ground to minimize the effect to the

environment and to keep low road gradient (maximum gradient is 6.3%). Concrete pipe culverts

with 300mm in diameter are placed under the road material at wadi sections (three sections) to

discharge the surface water flow. The detail of access road is shown in Table-2.

Table-2 Detailed Information on Access Roads

From To Width

(m)

Length

(m)

Maximum

Gradient

(%)

No of Side

Lay-by

Entrance from

National Road No.1

Junction Point (Near

the entrance of camp

site)

5.0 1,280.00 1.958 1

Junction Point Entrance of Pad A-1 5.0 1,709.01 6.307 2

Entrance of Pad A-1 Entrance of Pad A-2 5.0 328.58 5.714 0

Junction Point Entrance of Pad A-3 5.0 904.18 3.107 1

Progress Control and Inspection

All the works as earth works, paving and drainage works shall be controlled by the Contractor by

time to time whether the measured values meet the original drawings as specified.

Periodical inspections shall be conducted by the Contractor to reports the progress, and the Client

shall clarify the values to meet the drawings by using topographic/leveling equipment. Before the

completion of all the works, the Contractor shall be inspected at site by elevation of access road

and all well pads in the presence of the Client. If the tolerance is more than 5cm, the Client may

direct to the Contractor to meet the level to the drawings.

The Contractor shall submit the “completion drawing” when all the site inspections are passed by

the Client.

3

A-1 Clarification of Alignment

The Contractor shall carry out the topographic survey to clarify the road alignment and mark the

alignment at the sit by paint or peg. Based on the results, the Contractor submit shop drawings

to the Client for approval and visual clarification at the site.

A-2 Clearing and Grubbing

This work shall consist of all clearing and grubbing necessary for the performance of the works

covered by the contract in accordance with the specifications. The areas to be cleared, grubbed

and stripped shall be the areas designated in the drawings or the contract documents. It shall also

include the demolition, removal and disposal of structures that obtrude on or encroach upon or

obstruct the work, except where otherwise provided.

The Contractor shall carry out the clearing and grubbing works of the designated areas

considering the bushes, trees, hedges and boulders, shall be grubbed up and disposed off the site

by the Contractor.

Clearing and grubbing shall be performed within the construction width minimizing ground

disturbance as designated in the drawings. The cutting and removal work of plants in the site shall

be done as per the prevailing rules and regulations in Djibouti.

Existing roads, facilities, public utilities, services, and plants earmarked for preservation shall be

protected from harm or damage from the Client's operation.

A-3 Cutting

(1) General

This work shall consist of the excavation to make slope for access road and well pad. The

classification of soil excavation shall be done as the following manners:

Rock: Medium-hard to hard basaltic rock is distributed in the area then slope gradient

of 55 degree (1:0.7) is applied. The rock can be effectively excavated by ripping

with a bulldozer, breaker and static expansive demolition agent. Boulders should

be removed if it is located at shoulder of cutting slope.

Common soil: Sand or sandy soft soil which is combined in the gravel then slope gradient of 45

degree (1:1.0) is applied. The soil which can be effectively removed by shovel

excavator or bulldozers.

(2) Equipment

The Contractor shall prepare adequate equipment to carry out suitable excavation works as

prescribed in the specifications.

4

(3) Construction Method

The excavation shall be carried out with provision of partial protection or shall be compensated

where deemed necessary to prevent from any damages to public utilities. No blasting operations

shall be carried out without permission from the Client. The Contractor shall carry out blasting

works in conformity with enforced regulations in Djibouti. Any damage to third parties outside

of the construction area caused under this work shall be compensated for at the Contractor’s

expense.

The excavated rock larger than 30 or 50cm shall be broken up to less than 30 to 50 cm in diameter.

The material excavated and broken up shall be loaded to a delivery vehicle.

Excess excavation in cut sections shall be refilled with suitable material without extra

measurement and payment. If so, the Contractor shall remove unsuitable excavated materials for

use in embankment and dispose it off. The disposed materials shall be removed, hauled and

stocked in a stock yard as waste prepared by the Contractor. As a minimum requirement, the

Contractor shall undertake slope stabilization measures for spoil banks on governmental lands.

For spoil banks on land prepared by the Contractor, the Contractor himself shall be responsible

for stabilizing them.

A-4 Embankment

(1) General

This work shall cover all embankment works for earth structures to be constructed for access

road and well pads as shown in the drawings which includes the following operations:

1) Preparation of foundation for embankment,

2) Placing and compaction of embankment materials, and

3) Quality control on embankment materials.

(2) Materials

All materials excavated by making access road and well pads shall be effectively used for the

embankment, except unsuitable materials such as top soil including organic soil and plants. The

Contractor shall control the quality on embankment materials by removing organic soil and plants

when it is excavated.

(3) Equipment

The Contractor shall prepare adequate equipment to carry out suitable embankment works as

prescribed in the specifications.

5

(4) Construction Method

1) Preparation of foundation

No material shall be placed in any section of the embankment site until the foundation has been

suitably prepared in a manner approved by the visual check. The Contractor shall check the

ground conditions, and if necessary, remove unstable ground or compact loosen parts to be firm

before embankment work. Any damage to a third party outside of the construction area caused

under this work shall be compensated for at the Contractor’s expense.

Preparation of the foundation for the embankment shall be checked by the Client. If the condition

of the foundation is not satisfactory, the Contractor shall implement additional work.

2) Placing and compaction of embankment materials

Because the excavated rock size differs from fine soils to boulders, the Contractor shall check the

size of excavated rock size broken up to less than 30 to 50 cm at excavation. Excavated rocks

shall be moved to the nearest embankment areas by bulldozer and/or dump tracks.

Compaction shall be conducted by rollers on the embankment with grading.

Any rock fragments found in the placed material which is larger than 30 to 50 cm shall be removed

or crushed before the material is compacted.

(5) Quality control on embankment materials

The Contractor perform the field and laboratory tests on embankment materials, provide a trained

staff to the satisfaction of the Client, to conduct all necessary tests to ensure that the embankment

materials satisfy all requirements of the specifications.

Soil tests shall be conducted at embankment points where the surface is composed of

embankment to investigate the strength of the ground of well pad. The test shall be conducted

after placing of embankment material before compacting. The test shall be complying with

ASTM D 1586 (Standard penetration test) and conducted at the following locations on the

access road:

- P17, P49, P86, P141, P145, p32, p41, p43 (eight points)

Field and laboratory tests on embankment materials shall be in accordance with testing methods

and recommended practices of the American Society for Testing and Materials (ASTM D1557).

The minimum control value shall be not less than 90% of the density of compaction of original

embankment material, and not less than 85 % of saturation of original of embankment material.

6

A-5 Paving

(1) General

This work shall consist of preparation of gravel (crushed stone) and sand material treatment

of access road surface, hauling, spreading and compacting the materials on excavated and/or

embanked base, in accordance with these specifications and the lines, levels, grades,

dimensions and cross sections shown in the drawings.

(2) Materials

Materials for gravel shall be sound, durable crushed rocks, boulders and stones blended with

natural coarse sand, the combined grading of which shall be within the following specified

limit as shown in Table-3:

Table-3 Particle Size Distribution for Gravel

Sieve size Total percent passing

50.8 mm 100

25.4mm 70 - 90

19.1mm 50 - 85

4760 µ 25 - 60

420 µ 10 - 30

74 µ 0 - 15

(3) Construction Method

1) Preparation

Any ruts, holes, defects or soft, yielding places that occur in the base by reason of any improper

drainage condition, traffic or hauling over of the same or for any other cause, shall be corrected

and compacted to the required stability and complied with the smoothness.

2) Spreading

Gravel shall be spread in layers of not over 15 cm compacted thickness and compacted with

bulldozers and/or shovel excavators.

After the gravel has been spread and before compaction begins, the edges shall be backed up

with sub-base materials to such a height that the sub-base in shoulder portion will be

compacted to the height of the course as shown in typical cross section of the drawings.

7

3) Compaction

Compaction of gravel shall be done after spreading operation and roller shall begin at the edge

of the layer. The rolling shall be from the low side to the high side. Water in the amount that

is necessary for achieving the required compaction shall be added during rolling.

Any irregularities that develop in the surface of the gravel during rolling shall be corrected by

loosening the surface, adding or removing material and re-compacting until the surface

presents a smooth regular appearance. Gravel shall be compacted to the thickness and cross

section as shown on the drawings and shall not vary by more than 10 cm from the required

elevation. All humps and depressions and thickness deficiencies exceeding the tolerances of

more than 5cm shall be corrected by removing the defective work or by adding new material.

4) Inspection and Tests

The Contractor shall report the progress of compacting work to the Client every week by

construction report, and the Client check the compacting procedure and compacted surface

based on at the site. The Contractor shall propose the tests of compacted surface in accordance

with testing methods and recommended practices of the American Society for Testing and

Materials (ASTM D1557). The minimum control value shall be not less than 90% of the

density of compaction of original embankment material, and not less than 85 % of saturation

of original of embankment material.

A-6 Drainage

(1) General

This work shall consist of construction of crossing structure of seasonal stream (wadi) drain

and underpass for water supply pipeline. Precast concrete culvert is applied for this work, to

be put to the place specified in the drawings.

(2) Material

Precast concrete pipe shall be procured to ensure the strength which shall comply with ASTM

C1417–15 or equivalent. For river crossing and passing for water supply pipeline, thickness of

wall shall not be less than 30mm and bearing strength shall be not less than 17.7 kN/m. The

surface of the finished units shall be smooth, dense and hard with clean sharp arises (except where

otherwise indicated) and shall be free from cracks, discoloration, holes, fins, honeycombing,

watermarks, dusting or shutter marks.

(3) Construction Method

Units shall be manufactured and cured in a properly equipped casting yard or shop and the

arrangements shall be subject to the inspection and approval of the Client. The Contractor shall

give adequate notice to the Client before dispatching precast units to the site and, if the Client so

8

requires, shall provide facilities for inspection, test loading and dimensional checking of the units

before they are dispatched. In case the units are constructed in a factory or yard remote from

the site, details of the concrete components, mix design and compression test results shall be made

available to the Client. Details of the design shall be subject to approval by the Client as required.

Special lifting arrangements shall be incorporated in the design to eliminate damage to arises and

surfaces during handling and erection.

The Contractor shall mark and identify the points where the underpass is constructed before

embankment work is commenced. Gravel with sand shall be laid as a foundation. Concrete pipes

shall be set at the bottom of embankment and connected all by mortar before the embankment

work is commenced. The embankment or backfill rocks shall be smaller, less than 15cm around

the concrete pipes not to give damage the pipe. Compaction shall not be done until the thickness

of embankment is reached 1.0m above underpass.

B. Base Camp and Well Pad Preparation

General

This work shall consist of excavation/cutting, forming embankment grading and compaction of

compounds, digging and smoothening of water pit and placing concrete at geothermal well pad.

Total three well pads and one base camp are planned to be constructed. The well pad is a land lot

where a drilling rig is erected, and the drilling works are undertaken. The base camp is located at

the flat ground adjacent of the junction of access road with the size of 0.02 km2 (200 x 100m).

Dimension of well pad are different from each well pad as shown in Table-3 because of

topography. All the compound should be covered by gravels and compacted. Water pit is

constructed for A-1 and A-3 well pads with the size of 40 x 13m in area with 2.0m deep. Concrete

is casted at the bottom of each water pit to protect linings to be covered. Concrete base is classified

by two types, the concrete base of A-1 is the size of 10 x 25 x 0.4 m, and that of A-2 and A-3 is

the size of 10 x 10 x 0.4m, and drilling cellar for geothermal well drilling shall be constructed at

each well pad.

General information of well pads are shown in Table-4 and Table-5.

Table-4 General Information of Well Pad Preparation

Name Area (m2) No. of basement

No. of

Drilling

cellar

Water Pit

Excavation

(m3)

Sump Pit

Excavation

(m3)

Well Pad A-1 5,155 1 (10x45x0.4m) 2 963 62.5

Well Pad A-2 4,520 1 (10x10x0.4m) 1 None 62.5

Well Pad A-3 5,362 1 (10x10x0.4m) 1 990 62.5

9

Table-5 Well Pad Location (UTM 38N)

Name Corners of Well Pad

X Coordination Y Coordination

Well Pad A-1

191761.58 1262278.87

191843.17 1262244.74

191810.24 1262300.03

191761.58 1262323.25

191780.82 1262324.76

Well Pad A-2

192145.06 1262533.53

192067.62 1262517.21

192058.09 1262463.27

192156.45 1262485.19

Well Pad A-3

191010.13 1263334.99

191049.16 1263303.74

191091.92 1263356.76

191115.02 1263402.87

191093.45 1263419.96

191051.13 1263386.16

Progress Control and Inspection

All the works as earth works and laying of gravels shall be controlled by the Contractor by time

to time whether the measured values meet the original drawings as specified.

Periodical inspections shall be conducted by the Contractor to reports the progress, and the Client

shall clarify the values to meet the drawings by using topographic/leveling equipment. Before the

completion of all the works, the Contractor shall be inspected by elevation of all the geothermal

well points and all the corners of well pad, dimension and depth of water pits and sump pits in the

presence of the Client. If the tolerance is more than 5cm, the Client may direct to the Contractor

to meet the level to the drawings.

The Contractor shall submit the “completion drawing” when all the site inspections are passed by

the Client.

B-1 Clarification of Area

The Contractor shall carry out topographic survey to clarify the area to be constructed and mark

all the corners by paint or peg. Based on the results, the Contractor submit shop drawings to the

Client for approval and visual clarification at the site.

B-2 Clearing and Grubbing

(Description is as same as A-2 Clearing and Grubbing)

B-3 Cutting

(Description is as same as A-3 Cutting)

10

B-4 Embankment

(Description is as same as A-4 Embankment)

B-5 Laying of Gravel

(1) General

This work shall consist of preparation of gravel (crushed stone) and sand material treatment

of well pad surface, hauling, spreading and compacting the materials on excavated and/or

embanked base, in accordance with these specifications and the lines, levels, grades,

dimensions and cross sections shown in the drawings.

(2) Materials

Materials for gravel shall be sound, durable crushed rocks, boulders and stones blended with

natural coarse sand, the combined grading of which shall be within the specified limit as shown

in Table-3 in previous Section A-5.

(3) Construction Method

1) Preparation

Any ruts, holes, defects or soft, yielding places that occur in the base by reason of any improper

drainage condition, traffic or hauling over of the same or for any other cause, shall be corrected

and compacted to the required stability and complied with the smoothness.

2) Spreading

Gravel shall be spread in layers of not over 15 cm compacted thickness and compacted with

bulldozers and/or shovel excavators.

3) Compaction

Compaction of gravel shall be done after spreading operation and roller shall begin at the edge

of the layer. The compaction shall be from the low side to the high side. Water in the amount

that is necessary for achieving the required compaction shall be added during rolling.

Any irregularities that develop in the surface of the gravel during rolling shall be corrected by

loosening the surface, adding or removing material and re-compacting until the surface

presents a smooth regular appearance. Gravel shall be compacted to the thickness and cross

section as shown on the drawings and shall not vary by more than 10 cm from the required

elevation. All humps and depressions and thickness deficiencies exceeding the tolerances of

more than 5cm shall be corrected by removing the defective work or by adding new material.

11

4) Testing

a) Test for Embankment

Standard penetration tests shall be conducted to investigate the strength of the ground of well

pad. The test shall be conducted after placing of embankment material before compacting. The

test shall be complying with ASTM D 1586 (Standard penetration test) and conducted at the

following locations:

Well Pad A-1: at location of cellar of GB-3, another cellar, embankment part of south-western

and north-western side of well pad (4 locations)

Well Pad A-2: at location of Cellar, embankment part of northern and western side of well pad

(3 locations)

Well Pad A-3: at location of Cellar (pad area will be mainly composed of rock surface)

If the ground strength is less than N = 30, the location shall be excavated at the depth which

strength is upper than N = 30 and replaced to the gravel materials that are specified by A-5

(2). Then, the additional test shall conduct again at the same point whether the required value

(N=30) is secured.

b) Test for compaction of gravel

Compaction tests shall be conducted on the same place of standard penetration test in accordance

with testing methods and recommended practices of the American Society for Testing and

Materials (ASTM D1557). The minimum control value shall not be less than 90% of the density

of compaction of original material, and not less than 85 % of saturation of original material.

B-6 Construction of Water Pit

(1) General

This work shall consist of excavation of water pits on the well pad A-1 and A-3, compacting

pit walls, and casting of concrete at the bottom in accordance with these specifications and the

lines, levels, gradients, dimensions and cross sections shown in the drawings. The work shall

be conducted during or after well pad construction.

(2) Construction Method

The bottom and side slopes of common excavation upon or against which structures are to be

placed shall be finished accurately to the established lines and grades, and loose materials on the

surface so prepared shall be tampered with suitable tools and equipment to form a firm foundation

for the structures. The side slope shall be 45 degree and maximum depth shall be set concordant

with the Drawings.

After the excavation, concrete shall be casted at the bottom of the pit with the thickness shown in

12

the drawings.

If, at any point, excavation is made beyond the established lines, the over excavation shall be

filled with excavated materials which shall be approved and thoroughly compacted by tamping

or rolling to smoothen the surface not to give damage to lining materials to be covered.

If, at any point, hard rock is appeared less than the depth of 2.0m during excavation, adjust the

excavation volume to meet the amount for excavation volume up to the planned excavation

volume (as shown in Table-4) by widening excavation area or banking of pit by excavated soils.

B-7 Construction of Sump Pit

(1) General

This work shall consist of excavation of sump pits on the well pad A-1, A-2 and A-3, compacting

pit walls, and plastering of mortar at the bottom and walls in accordance with these specifications

and the lines, levels, gradients, dimensions and cross sections shown in the drawings. The work

shall be conducted during or after well pad construction.

(2) Construction Method

The bottom and side slopes of common excavation upon or against which structures are to be

placed shall be finished accurately to the established lines and grades, and loose materials on the

surface so prepared shall be tampered with suitable tools and equipment to form a firm foundation

for the structures. The side slope shall be 45 degree and maximum depth shall be set concordant

with the Drawings.

If, at any point, excavation is made beyond the established lines, the over excavation shall be

filled with excavated materials which shall be approved and thoroughly compacted by tamping

or rolling to smoothen the surface not to give damage to lining materials to be covered.

If, at any point, hard rock is appeared less than the depth of 2.0m during excavation, adjust the

excavation volume to meet the amount for excavation volume up to the planned excavation

volume (as shown in Table-4) by widening excavation area or banking of pit by excavated soils.

(3) Plastering of Mortar

After the excavation, meshed iron wire shall be covered at the bottom and the wall of the pit prior

to casting mortar.

Mortar shall be composed of fine aggregate complying with BS 882, BS 1199, BS 1200 or

equivalent, and ordinary Portland cement complying with BSEN 197-1:2000 or equivalent. The

mix proportions shall be one (1) part of cement to three (3) parts of fine aggregate by weight and

mechanical mixer shall be used to mix. The water content of the mortar shall be as low as possible

consistent with the use for which is required, but in any case the water/cement ratio shall not be

more than 0.5.

13

Mortar shall be plastered to more than 10cm by the machine or hand, and the surface shall be

finished smoothly without any cracks. The curing process shall be referred to B-9 (4) 9) Curing

of Concrete.

B-8 Lining of Water pit and Sump pit

(1) Material

Lining materials shall be fulfilled with the following requirements;

1) Materials

Material shall be HDPE or LLDPE and its property of material are shown below;

Table-6 Material to be used for Lining

Property Test Method HDPE LLDPE

Density (g/cm3) ASTM D 1505 >0.932 >0.915

Melt Flow Index (g/10 min) ASTM D 1238 (190/2.16) <1.0 <1.0

OIT (minutes) ASTM D 3895 (1 atm/2000C) >100 >100

2) Thickness: Not less than 1.5 mm

3) Joining: heating or adhesion

(2) Lining at pit bottom and slope

Lining material should be confirmed if there are holes or damages prior to the lining, and pit

slopes should be checked and removed if the sharp materials or angular gravels in surface not to

damage the linings. Additional tempering/rolling should be necessary if pit bottom and/or slope

are soft and rough.

The general information of pits are shown in Table-7.

Table-7 General Information of Pits

Name Dimension (m) Depth (m) Slope (deg) Inner Area (m2)*

Water pit A-1 50.0 x 12.0 2.0 45 820

Water pit A-3 40.0 x 15.0 2.0 45 795

Sump pit A-1 12.0 x 7.0 2.0 45 147

Sump pit A-2 12.0 x 7.0 2.0 45 147

Sump pit A-3 12.0 x 7.0 2.0 45 147

*Margin is not included

(3) Jointing

Jointing shall be conducted with appropriate method for lining materials, as heating or adhesion.

14

After the jointing, visual inspection shall be necessary to clarify the work and defaulted parts.

(4) Fixing

The linings shall be fixed properly by weights or some other materials/equipment not to be moved

or damaged. In case of using anchor pin, it shall be used above the normal water level.

B-9 Concrete Works

(1) General

This work shall cover all concrete works for earth structures to be constructed for well pads

as shown in the drawings which includes the following operations:

1) Classification and required strength,

2) Placing and casting

3) Quality control

(2) Material

1) Cements

Cement shall comply with BSEN 197-1:2000 Ordinary and rapid hardening Portland Cement or

equivalent. Cement in bags shall be stored in a suitable weatherproof structure of which the

interior shall be dry and well ventilated at all times. The floor shall be raised above the

surrounding ground level and shall be so constructed that no moisture rises through it.

Each delivery of cement in bags shall be stacked together in one place. The bags shall be closely

stocked so as to reduce air circulation but shall not be stocked against an outside wall.

All cement used on the works shall be tested by the manufacturer or the Contractor in a laboratory

acceptable to the Client. The tests to be performed shall be those set out in BSEN 197-1:2000

or equivalent.

The Contractor shall keep full records of all data relevant to the manufacturer, delivery, testing

and use of all cement used in the Works and shall provide the Client with two (2) copies thereof.

An additional requirement is that the Portland cement shall have a guaranteed equivalent alkali

content not exceeding 0.6% expressed in the acid soluble alkali content of the cement.

2) Fine aggregate

Fine aggregate shall be clean, hard and durable and shall be natural sand, crushed gravel sand or

crushed rock sand complying with BS 882 or equivalent. To achieve an acceptable grading, it

may be necessary to blend materials from more than one source. Fine aggregate for mortar only

shall comply with BS 882, BS 1199, BS 1200 or equivalent. The fine aggregate shall be

15

reasonably graded.

The fine aggregate shall not contain iron pyrites or iron oxides. It shall not contain mica, shale,

coal or other laminar, soft or porous materials or organic matter unless the Contractor can show

by comparative tests, on finished concrete as set out in BS 1881, that the presence of such

materials does not adversely affect the properties of the concrete.

Other properties shall be as set out below:

(a) Chloride soluble in a 10 per cent solution by weight of nitric acid shall not exceed 0.05

per cent by weight expressed as chloride ion when tested as set out in BS 812, subject also to the

further restriction on total chloride content in Sub-clause III-1-2 (2).

(b) Sulphate soluble in a 10 percent solution by weight of hydrochloric acid shall not exceed

0.4 per cent by weight expressed as SO3, when tested as set out in BS 1377, subject also to the

further restriction given in the note on total sulphate content in Sub-clause III-1-2 (2).

(c) Soundness

After five (5) cycles of the test in AASHO T104, the aggregate shall not show a weight loss of

more than 10 percent.

(d) Organic impurities

The amount of deleterious substance in fine aggregate shall not exceed the limits prescribed

below:

Percent by weight

- Clay lump 1.0

- Material passing 0.074mm sieve 3.0

- Material retained on a 0.297mm sieve and floating

on a liquid having a specific gravity of 2.0 0.5

3) Coarse aggregate

Coarse aggregate shall be clean, hard and durable crushed rock, crushed gravel or natural gravel

complying with the requirements of BS 882 or equivalent. The material shall not contain any

iron pyrites, iron oxides, flaky or laminated material, hollow shells, coal or other soft or porous

material, or organic matter unless the Contractor can show by comparative tests on finished

concrete as set out on BS 1881 that the presence of such materials does not adversely affect the

properties of the concrete. The pieces shall be angular rounded or irregular as defined in BS 812

Part 1 or equivalent.

Coarse aggregate shall be supplied in the nominal sizes called for in the Specifications and shall

be graded in accordance with BS 882 for each nominal size.

Other properties shall be as set out below:

(a) The amount of deleterious substance in fine aggregate shall not exceed the limits

prescribed below:

16

Percent by weight

Clay lump 0.25

Soft particles 5.0

Material passing 0.074mm sieve 1.0*

Material floating on a liquid having a specific gravity of 2.0 1.0

(* In the case of crushed aggregate, if the material finer than 0.074mm sieve consists of rock dust

free from clay or shale, this may be increased to 1.5 percent.)

(b) The content of hollow and flat shells shall not be such as will adversely affect the

concrete quality when tested as set out in BS 1881. The total content of aggregate shall not be

more than the following:

40 mm nominal size and above : 2 % of dry weight

20 mm nominal size : 5 % of dry weight

10 mm nominal size : 15 % of dry weight

(c) Chlorides soluble in a 10 per cent solution by weight of nitric acid shall not exceed 0.03

per cent by weight, expressed as chloride ion when tested as set out in BS 812 but subject also to

the further restriction under the note on total chloride content hereunder. Sulphates soluble in a

10 per cent solution by weight of hydrochloric acid shall not exceed 0.4 per cent by weight

expressed as SO3 when tested as set out in BS 1377, subject also to the further restriction on total

sulphate content noted hereunder.

For any reinforced concrete : 0.3 per cent in 95 per cent of all test results provided no

result is more than 0.5 per cent.

The total sulphate content expressed as HSO3 of all ingredients in a mix including cement, water

and admixtures shall not exceed 0.4 per cent by weight of the aggregate or 4.0 per cent of the

weight of cement in the mix, whichever is the lesser.

(d) Soundness

After five (5) cycles of the test in AASHTO T104, the aggregate shall not show a weight loss of

more that 12 per cent.

4) Routine Testing of Aggregates

The Contractor shall carry out routine testing of aggregates for compliance with the Specifications

during the period that concrete is being produced for the Works. The tests set out below shall

be performed on aggregates from each separate source on the basis of one (1) set of test for each

day on which aggregates are delivered to the Site, and provided also that the aggregates are of

uniform quality. If the aggregate from any source is variable, the frequency of testing shall be

increased.

17

5) Delivery and storage of aggregate

Aggregates shall be delivered to the Site in clean and suitable vehicles. The storage of

aggregates shall be arranged so that as far as possible rapid drying out in hot weather is prevented

in order to avoid sudden fluctuations in water content. Storage of fine aggregates shall be

arranged so that they can drain sufficiently before use to prevent fluctuations in water content of

the concrete.

The free moisture content of the fine aggregate and of the smallest size of coarse aggregate, as

delivered to the mixers, shall be controlled to not to exceed 4.0% and 1.0%, respectively, by

weight of the saturated surface dry aggregates.

6) Water for Concrete and Mortar

Sea water, brackish water or groundwater containing more than 1,000ppm chloride ion or

2,000ppm sulphate ion shall not be used for mixing or curing concrete.

Water shall be clean and free from harmful matter and shall comply with the requirements of BS

3148 or equivalent.

The Contractor shall carry out tests in accordance with BS 3148 to establish compliance with the

Specifications.

(3) Concrete Mixes

1) Types of Concrete

The types of structural concrete to be used in the Works shall be as designated in Table-8 and

Table-9.

Table-8 Type of Concrete

Type

Minimum compressive

strength at 28 days

(N/mm2)

Nominal max. size

of aggregate

(mm)

Range of

slump

(cm)

Min. cement

content

(kg/m3)

Grade 15 16 40 6 – 12 250

Grade 20 21 20 6 – 12 310

Table-9 Usage of Concrete

Type Usage

Grade 15 Bottom of Water Pit (generally used as lean concrete)

Grade 20 Concrete base, wall and bottom of drilling cellar (generally used as structural

concrete)

2) Trial Mixes

At least six (6) weeks before commencing placement of concrete in the Permanent Works, the

18

Contractor shall make trial mixes, by using the aggregates proposed for the work to ensure that

the concrete is sufficiently workable and that segregation of the mix, during transportation and

placing, does not occur. The composition of the trial mixes shall comply with the requirements

of the specifications in all respects. The results shall be submitted to the Client for his approval.

(a) The slump of the concrete shall be determined.

(b) Six (6) test cylinders 15cm in diameter and 30cm high shall be cast from each batch.

(c) Three (3) cylinders from each batch shall be tested for compressive strength at seven (7)

days and the remaining three (3) at 28 days.

(d) The density of all the cylinders shall be determined before the strength test are carried out.

Subject to the agreement of the Client, the compacting factor apparatus may be used in place of a

slump cone. In this case the correlation between slump and compacting factor shall be

established during preparation of the trial mixes.

The Contractor shall also carry out test to determine the drying shrinkage of the concrete.

The Contractor may use a cubic specimen, instead of the cylinder, for the test in conformity with

the Client’s approval.

Based on the results of the test of the trial mixes, the Contractor shall submit full details of his

proposals for mix design to the Client, including the type and sources of each ingredient, the

proposed proportions of each mix and the results of the test on the trial mixes.

(4) Construction Method

1) Preparation of Surface to Receive Concrete

Before deposition of further Concrete, existing concrete surface shall be cleaned, hard and sound

and shall be wet but without any free-standing water.

Surfaces against which concrete is to be placed shall receive a prior coating of mortar mixed in

the proportions similar to those of the fines portion in the concrete to be placed. The mortar

shall be kept ahead of concrete. The mortar shall be well worked into all parts of the excavated

surface and shall be not less than 5mm thick.

2) Mixing by mechanical mixer

The materials for concrete shall be mixed in a mechanical mixer. The mixing time for each batch

shall not be less than the minimum mixing time, shall not exceed three times of the minimum

time, and shall be constant for series of concrete for a particular structure. The mixing time shall

start when all the ingredients are in mixer and shall be longer than one and half minute. The

mixer shall not be loaded beyond their rated capacity nor shall they be operated at a speed in

excess of that recommended by the manufacture. They shall produce a concrete of uniform

consistency and appearance, at a continuous rate. All mixing equipment shall be clean before

commencing mixing and shall be kept free from set concrete.

19

3) Mixing by hand

No concrete either for structural purpose or non-structural concrete shall be allowed to be mixed

by hand.

4) Transport

The concrete shall be transported to the site of placing by means which shall prevent adulteration,

segregation or loss of ingredients, and which shall ensure that the concrete is of the required

workability at the point and time of placing. The time between discharge from the mixer and

placing shall not exceed 30 minutes. The loss of slump between discharge from the mixer and

placing shall not exceed 25mm.

5) Placing Procedures

The concrete shall be deposited as nearly as possible in its final position and placed to avoid

segregation of the concrete and displacement of the reinforcement, other embedded items, or

formwork.

Layers shall not be placed so that they form feather edges nor shall they be placed on a previous

layer which has taken its initial set. In order to comply with this requirement, a layer may be

started before completion of the proceeding layer.

All the concrete in a single bay or pour shall be placed as a continuous operation. It shall be

carefully worked around all obstructions, irregularities in the foundations and the like so that all

parts are completely full of compacted concrete with no segregation or honeycombing.

All works shall be completed on each batch of concrete before its initial set commences and

therefore the concrete shall not be disturbed before it has set hard. No concrete that has partially

hardened during transit shall be used in the Works and the transport of concrete from the mixer to

the point of placing shall be such that this requirement can be complied with.

Concrete shall not be placed during rain which is sufficiently heavy or prolonged to wash mortar

from coarse aggregate on the exposed faces of fresh concrete. Means shall be provided to

remove any water accumulation on the surface of the placed concrete. Concrete shall not be

deposited into such accumulation of water.

Covers shall be provided for all fresh concrete surfaces which are not being worked on. Water

shall not be added to concrete for any reason.

Forms for walls, columns and other thin sections of significant height shall be provided with

openings or other devices that will permit the concrete to be placed in a manner that will prevent

segregation and accumulations of hardened concrete on the formwork or reinforcement above the

level of the placed concrete.

The temperature of concrete when it is being placed shall generally be not more than 32oC. If

temperature is over, the Contractor shall employ effective means, such as refrigerating the mixing

20

water, adding chipped or flaked ice to the mixing water, placing at night, or a combination of

methods to maintain the temperature of the concrete, as it is placed, below 32oC.

If concrete placing is interrupted for any reason and the duration of the interruption cannot be

forecast or is likely to be prolonged, the Contractor shall immediately taken the necessary action

to form a construction joint so as to eliminate as far as possible feather edges and sloping top

surfaces and shall thoroughly compact the concrete already placed. All work on concrete shall

be completed while it is still plastic and it shall not therefore be disturbed until it is hard enough

to resist damages. Plant and materials to comply with those requirements shall be readily

available at all times during concrete placing.

Before concreting is resumed after such an interruption, the Contractor shall cut out and remove

all damaged or uncompacted concrete, feather edges or any other undesirable features and shall

leave a clean sound surface against which the fresh concrete may be placed.

If it becomes possible to resume concrete placing without contravening the Specifications and the

Client consents to a resumption, the new concrete shall be thoroughly worked in and compacted

against the existing concrete so as to eliminate any cold joints.

6) Dimensions of Pours

Pours shall not be more than two (2) m high and shall as far as possible have a uniform thickness

over the plan area of the pour. Concrete shall be placed to the full planned height of all pours.

The Contractor shall plan the dimensions and sequence of pours in such a way that cracking of

the concrete does not take place due to thermal or shrinkage stresses.

7) Placing Sequence

The Contractor shall arrange that as far as possible the intervals between placing successive lifts

of concrete in one (1) section of the Works are of equal duration. This duration shall normally

be not less than three (3) or more than seven (7) days under temperate weather conditions.

Concrete shall not be placed against adjacent concrete which is less than 21 days old.

8) Compaction of Concrete

The concrete shall be fully compacted thoroughly to the full extent of the placed layer. It shall

be thoroughly worked against the formwork and around any reinforcement and other embedded

items, without displacing them. Particular care shall be taken at arises and other confined spaces.

Successive layers of the same pour shall be thoroughly worked together.

Concrete shall be compacted with the assistance of mechanical immersion vibrators, unless the

Client agrees another method.

Immersion vibrator is operated at a frequency of at least 7,000 cycles per minute. The

Contractor shall ensure that vibrators are operated at pressures and voltages not less than those

recommended by the manufacturer in order that the compact effort is not reduced.

21

A sufficient number of vibrators shall be operated to enable the entire quantity of concrete being

placed to be vibrated for the necessary period and, in addition, standby vibrators shall be available

for instant use at each place where concrete is being placed.

Vibrators shall be continued at each point until the concrete ceased to contract and a thin layer of

mortar has appeared on the surface and air bubbles have ceased to appear. Vibrators shall not

be used to move concrete laterally and shall be withdrawn slowly to prevent the formation of

voids.

Vibrations shall not be applied by way of reinforcement or shall vibrators be allowed to touch

reinforcement or other embedded items. The vibrators shall be inserted vertically into the

concrete to penetrate the layer underneath at regular spacing which shall not exceed the distance

from the vibrator over which vibration is visible effective.

9) Curing of Concrete

Concrete shall be protected during the first stage of hardening from loss of moisture and from the

development of temperature differentials within the concrete sufficient to cause cracking. The

methods used for curing shall not cause damage of any kind to the concrete.

Curing shall be continued for as long as may be necessary to achieve the above objectives but in

any case, for at least seven (7) days or until the concrete is covered by later construction whichever

is the shorter period.

The above objectives are dealt with in the following method but nothing shall prevent both

objectives being achieved by a single method where circumstances permit:

(a) Loss of moisture

Exposed concrete surface shall be closely covered with impermeable sheeting, properly secured

to prevent its removal by wind and the development of air spaces beneath it. Joints in the

sheeting shall be lapped by at least 300mm.

If for some reason it is not possible to use impermeable sheeting, the Contractor shall keep the

exposed surface continuously wet by means of a water spray or by covering with a water absorbent

material which is kept wet, unless this method conflicts with the method (b).

(b) Limitation of temperature differential

The Contractor shall limit the development of temperature differentials in concrete after placing

by any means appropriate to the circumstances including the following:

- Limiting concrete temperatures at placing;

- Use of low heat cement;

- Insulation of exposed concrete surface by insulating blankets. Such blankets shall have an

insulation value at least equivalent to 50mm of dry mineral wool;

- Leaving formwork in place during the curing period. Steel forms shall be suitably insulated

on the outside;

22

- Preventing rapid dissipation of heat from surfaces shielding from wind;

- Avoiding the use of water sprays when such use would cause rapid cooling of the surface.

(5) Protection of Fresh Concrete

Freshly placed concrete shall be protected from rainfall and from water running over the surface

until it is sufficiently hard to resist damage from these causes.

No traffic shall be allowed on any concrete surface until such time as it is hard enough to resist

damage by such traffic.

Concrete placed in the Works shall not be subjected to any loading until it has attained at least its

nominal strength as defined. If the Contractor desires to impose loads on newly placed concrete,

he shall make at least three (3) test cylinders and cure them in the same conditions as concrete

they represent. These cylinders shall be tested singly intervals in order to estimate the time at

which the nominal strength is reached.

(6) Quality Control of Concrete

1) Sampling

For each class of concrete in production at each plant, samples of concrete shall be taken at the

point of mixing or of deposition, all in accordance with the sampling procedures described in ISO

4109:1980 or equivalent and with the further requirements set out below.

A slump test shall be made immediately before concreting is commenced and at all times when

compression test samples are taken. The slump tests shall be in accordance with ISO 4109:1980

or equivalent. Each sample shall be taken from one (1) batch selected at random and at such

intervals that each sample represents not more than 20m3 of concrete.

2) Compressive strength test

A compressive strength test shall be executed during manufacture and placing of concrete with

not less than 3 samples for each day as to each type of concrete. Test cylinders 15cm in diameter

and 30cm high shall be molded from each sample and tested after cured properly for 28 days all

in accordance with the requirements of ISO 1920-3:2004 and ISO 1920-4:2005 or equivalent.

The test results shall be progressively analyzed and evaluated statistically.

The strength test results below the specified strength (described in Table 8) shall not be more than

25% of entire test results. The strength test results below 80% of the specified strength shall not

be more than 5% of entire test results.

3) Damaged or Defective Concrete

Defective concrete and concrete damaged from any cause shall be removed and replaced with

acceptable concrete by the Contractor at his own expense. Irregularities of alignment due to

23

inaccurate finishing of surfaces, bulging of forms, or other defects shall be rectified by and at the

expense of the Contractor.

(7) Reinforcement Steel Bars

Reinforcement which shall comply with the following British Standards or the equivalent, covers

plain and deformed bar reinforcement and steel fabric to be cast into concrete in any part of the

Works but does not include prestressing tendons or any other embedded steel:

BS 4449 or equivalent : Hot rolled plain bar and high yield deformed bar

BS 4482 or equivalent : Hand drawn mild steel wire

BS 4461 or equivalent : Cold worked steel bar

BS 4483 or equivalent : Steel mesh fabric

(8) Formworks

Formwork shall be constructed that they will support the loads imposed on them by the fresh

concrete together with additional stresses imposed by vibrating equipment and by construction

traffic, so that after the concrete has hardened the formed faces shall be in the positions shown on

the drawings.

Joints in formwork for exposed faces shall, unless otherwise specified, be evenly spaced and

horizontal or vertical and shall be continuous or form a regular pattern. All joints in formwork

including formwork for construction joints shall be tight against the escape of cement and fines.

Where reinforcement projects through formworks, the form shall fit closely round the bars.

Where overhangs on formwork occur, means shall be provided to permit the escape of air and to

ensure that the space is filled completely with fully compacted concrete.

(9) Particular Works

1) Drilling Cellar

Drilling cellar shall be constructed at the drilling point. The procedure is as follows;

a) Excavation at the drilling point

Excavate the drilling point at the minimum dimension of 3.3m x 2.1m with the depth of 2.0m.

The exact location of drilling points are shown in Table-10.

Table-10 Drilling Point (Center) (UTM 38N)

Well Pad Name Coordination (UTM 38N)

Remarks X Coord Y Coord

A-1 GB-3 191793.48 1262285.01 First test well to be drilled

GB-4 (Option-1) 191825.73 1262271.38 35m distance between GB-3

24

A-2 GB-4 (Option-2) 192114.31 1262501.36 -

A-3 GB-4 (Option-3) 191075.97 1263368.82 -

b) Pouring walls by concrete with formwork

Formwork shall be conducted for the size of 2.7m x 1.5m with the depth of 1.4m after placing the

gravels of 20cm thickness. Concrete wall shall keep more than 30cm thick.

c) Setting conductor pipe

Steel conductor pipe of Dia. 750mm (30”), 2.5m of length, SCH 10, thickness 7.9mm, plain end,

or equivalent shall be set at the center of drilling point.

d) Pouring bottom of drilling cellar

D11 iron bar shall be set with the interval of 20cm to prevent cracks of poured concrete. Drain pit

of 40cm x 40cm shall be made at the corner of the bottom at the adjacent of precast concrete pipe.

2) Concrete Base

Concrete base shall be constructed at around drilling cellar in each Well pad. Standard dimension

shall be 10.00m x 10.00m x 40cm thick after placing the gravels of 20cm thickness. D18 iron bar

shall be set with the interval of 20cm at the top and the bottom of the base. The details are

described as follows;

a) Well Pad A-1

Two (2) test wells are planned to be drilled, and the distance between them is 35m. In this situation,

concrete base shall be connected, and dimension shall be changed to 10.00m x 45.00m (see the

drawings).

b) Well Pad A-2 and A-3

One (1) test well is planned to be drilled, then dimension shall be 10.00m x 10.00m x 40cm thick

after placing the gravels of 20cm thickness (as same as the standard).

B-10 Fencing

(1) General

The Contractor shall furnish and install wire mesh fencing to be surrounded the area of camp site,

A-1, A-2, A-3 well pads, and five (5) water well sites. The amount is shown in Table-11. The

fencing shall consist of chain wire mesh, posts and accessories.

The Contractor shall install the gates at the entrance of each site. The standard width of gate is

5.0m but not limited to.

The chain wire mesh shall be 50mm mesh woven with 3.2mm dia. steel wire. Posts shall be

made of steel or concrete, maximum spacing of 2m with foundation of more than 30cm, fixing

with mortar or concrete at the bottom. The height of fence shall be not less than 2.0m from the

25

ground. Sub posts, tension wires, barbed wire and accessories shall be as approved. All

miscellaneous ferrous metalworks shall be galvanized or anti-corrosion.

The gates shall be of steel and/or timber, complete with all necessary fittings for hanging and

fastening.

Table-11 Length of Fencing

Site Length (m)

Camp Site 593

Well Pad A-1 288

Well Pad A-2 284

Well Pad A-3 267

Water Well site 360 (12x6m, 5 sites)

Total 1,792

*** End of Document ***

26

Appendix-1 Work Volume

1. Access road construction

No. Work Item Unit Quantity

A-1 Clarification of Alignment LS 1

A-2 Clearing and Grubbing m2 21,240

A-3 Cutting m3 17,385

A-4 Embankment m3 6,089

A-5 Paving by gravel m3 10,695

A-6 Drainage (30mm precast concrete pipe) m 210

2. Camp site and well pad preparation

No. Work Item Unit Quantity

B-1 Clarification of Area LS 1

B-2 Clearing and Grubbing m2 28,792

B-3 Cutting m3 6,290

B-4 Embankment m3 11,571

B-5 Soil excavation for Water pit on pad A-1 and A-3 m3 1,683

B-6 Laying of Gravel for Camp site m3 3,000

Laying of Gravel for Well pad m3 4,511

B-7 Soil excavation for Sump pit on pad A-1, A-2 and A-3 m3 312

Plastering of mortar at the bottom and the wall m3 33

B-8 Lining of Water pit and Sump pit m2 2,056

B-9 Cast in situ concrete for bottom of Water pit

(Grade 15, 15cm thickness)

m3 115

Cast in situ concrete for rig base and drilling cellar (Grade 20) m3 286

Conductor pipe (dia 30”, 2.5m) nos 4

B-10 Fencing m 1,792

3. Summary of earth work (Cutting and Embankment)

Section/Location Embankment (m3) Cutting (m3)

Entrance to Junction 1,826 2,233

Junction – Well Pad A-2 3,156 9,458

Junction – Well Pad A-3 1,107 5,694

Sub-Total for Access road 6,089 17,385

27

Summary of earth work (Cutting and Embankment)

Section/Location Embankment (m3) Cutting (m3)

Construction of Well Pad A-1 3,164 1,558

Construction of Well Pad A-2 8,342 964

Construction of Well Pad A-3 55 3,768

Sub-Total for Well Pad 11,571 6,290

Grand Total 17,660 23,675

28

Appendix-2 Bill of Quantity for

<Title of the Project>

No. Work Item Unit Quantity Unit Price Total

- Mobilization and Demobilization, LS 1

A-1 Clarification of Alignment LS 1

A-2 Clearing and Grubbing m2 21,240

A-3 Cutting m3 17,385

A-4 Embankment m3 6,089

A-5 Paving by gravel m3 10,695

A-6 Drainage (30mm precast concrete pipe) m 210

B-1 Clarification of Area LS 1

B-2 Clearing and Grubbing m2 28,792

B-3 Cutting m3 6,290

B-4 Embankment m3 11,571

B-5 Soil excavation for Water pit on pad

A-1 and A-3

m3 1,683

B-6 Laying of Gravel for Camp site m3 3,000

Laying of Gravel for Well pad m3 4,511

B-7 Soil excavation for Sump pit on pad A-

1, A-2 and A-3

m3 312

Plastering of mortar at the bottom and

the wall

m3 33

B-8 Lining of pits (Lining of 2 water pits

and 3 sump pits)

m2 2,056

B-9 Cast in situ concrete for bottom of

Water pit and (Grade 15, 15cm

thickness)

m3 115

Cast in situ concrete for rig base and

drilling cellar (Grade 20)

m3 286

Conductor pipe (30”) Nos 4

B-10 Fencing m 1,792

Total

VAT

GRAND TOTAL