section 2 earthworks

Standard Specification For Road Works

Cawangan Jalan, Ibu Pejabat JKR, K.L

FOR INTERNAL USE ONLY

SECTION 2

EARTHWORKS




SECTION 2 - EARTHWORKS

Page

2.1 CLEARING, GRUBBING AND STRIPPING TOPSOIL S2-35

2.1.1 Description S2-352.1.1.1 Clearing S2-352.1.1.2 Grubbing S2-352.1.1.3 Stripping Topsoil S2-35

2.1.2 Construction Methods S2-352.1.2.1 Areas To Be Cleared S2-352.1.2.2 Areas To Be Cleared, Grubbed and Stripped Of Topsoil S2-362.1.2.3 Topsoil S2-362.1.2.4 Timber S2-362.1.2.5 Structures S2-372.1.2.6 Disposal Of Material S2-37

2.2 EARTHWORKS S2-38

2.2.1 Definitions S2-38

2.2.2 General Requirements S2-39

2.2.3 Roadway Excavation S2-392.2.3.1 Dimensional Tolerances S2-392.2.3.2 Separation and Stockpiling of Suitable Material S2-402.2.3.3 Removal of Excavated Material From Site S2-402.2.3.4 Removal of Unsuitable Material S2-402.2.3.5 Replacement of Unsuitable Material Under Standing Water S2-402.2.3.6 Widening Cuts S2-402.2.3.7 Excavation of Rock S2-412.2.3.8 Storage and Handling of Explosives S2-422.2.3.9 Blasting S2-422.2.3.10 Safety Measures S2-422.2.3.11 Insecure Material S2-43

2.2.4 Earth Embankment S2-432.2.4.1 Material S2-432.2.4.2 Borrow Pits S2-432.2.4.3 Placement of Fill Material S2-432.2.4.4 Compaction S2-44

2.2.5 Rock fill Embankment S2-45

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Page

2.2.6 Embankment Over Soft Ground S2-462.2.6.1 Foundation Treatment S2-462.2.6.2 Surcharge and Staged Construction S2-462.2.6.3 Settlement Markers S2-462.2.6.4 Settlement Records S2-47

2.2.7 Subgrade S2-47

2.2.8 Protective Vegetation for Erosion Control S2-482.2.8.1 Topsoil S2-482.2.8.2 Turfing S2-482.2.8.3 Seeding S2-48



SECTION 2 - EARTHWORKS

2.1 CLEARING, GRUBBING AND STRIPPING TOPSOIL

2.1.1 Description

This work shall consist of clearing, grubbing and stripping topsoil in the areas designated hereunder and/or shown on the Drawings and/or directed by the S.O., and of clearing only in other areas designated hereunder and/or shown on the Drawingsand/or directed by the S.O., all as specified herein and as required by the S.O. The work shall also includethe demolition and disposal of structures in said areas, except whereotherwise provided for in the Contract, as specified herein and as required by the S.O.

2.1.1.1 Clearing

Clearing shall consist of the cutting and/or taking down, removal and disposal of everything above ground level, including objects overhanging the areas to be cleared such as tree branches, except such trees, vegetation, structures or parts of structures, and other things which are designated in the Contract to remain, or be removed by others, or which the S.O. directs are to be left undisturbed. The materialto be cleared shall include but not necessarily be limited to trees, stumps (parts above ground), logs, brush, undergrowth, long grasses, crops, loose vegetable matter and structures (except those structures whose removal or clearance is otherwise provided for in the Contract).

Clearing shall also include thelevelling of obsolete dikes, terraces, ditches, etc., unless otherwise directed by the S.O.

2.1.1.2 Grubbing

Grubbing shall consist of the removal and disposal of surface vegetation, the bases of stumps, roots, the underground parts of structures, and other obstructions to a depth of at least 0.50 metre below ground level, all to the satisfaction of the S.O.

2.1.1.3 Stripping Topsoil

Stripping topsoil shall consist of the removal of topsoil to an average depth of at least 100 mm below ground level, and its stockpiling for use in the Works, and/or its disposal, as directed by the S.O.

2.1.2 Construction Methods

2.1.2.1 Areas To Be Cleared

The entire road reserve area shall be cleared as described above, unless otherwise shown on the Drawings and/or directed by the S.O.

Clearing shall be carried out to the extents deemed necessary andapproved or directed by the S.O. in areas outside the road reserve where channel excavation or other work is required.

In areas which are to be cleared only, and in which grubbing and stripping topsoil are not required, the methods of work shall be such as will not unduly damage the surface vegetation and topsoil, and care shall be taken




not to disturb the topsoil and the root systems of grasses and other surface vegetation. No topsoil shall be removed from such areas, except as directed by the S.O., and any topsoil, grasses andother surface vegetation otherwise removed or disturbed shall be replaced and made good at theContractor's own expense, all to the satisfaction of the S.O.

2.1.2.2 Areas To Be Cleared,Grubbed and Stripped Of Topsoil

Except as otherwise shown on the Drawings and/or directed by the S.O., clearing, grubbing and stripping topsoil shall be carried out in all areas of roadway excavation and in all areas where embankment is to be constructed,except that grubbing and stripping topsoil shall not be carried out in those areas where :-

i) embankment is to be constructed on earth designated as swamp or soft ground;

ii) embankment is to be constructed to a height at the centre-line of 1.50 metres or more on ground with a cross-slope of not more than 1(vertical) to 30 (horizontal).

Clearing, grubbing and stripping topsoil shallbe carried out to the extents deemed necessaryand approved or directed by the S.O. in areasboth inside and outside the road reserve wherechannel excavation or other work is required.

Except where further excavation is required,holes and cavities in the ground surface afterclearing, grubbing and stripping topsoil shall befilled with materials similar to the adjacentground, and such fill shall be compacted to adry density similar to that of the surroundingmaterial, all to the satisfaction of the S.O.

This work shall be considered incidental to the work of clearing,grubbing and stripping topsoil, and shall not be measured for payment.

2.1.2.3 Topsoil

Topsoil to be stockpiled for the Works shall be sufficiently fertile to promote and support the growth of vegetation, and shall betaken from such areas where clearing, grubbing and stripping topsoil is required as approved or directed by the S.O. Before stockpiling, topsoil shall be separated from objectionable materials, all to the satisfaction ofthe S.O. The Contractor shall arrange for stockpile sites either within or outside the road reserve, at his own expense, and all to the satisfaction of the S.O.

Otherwise, topsoil removed during grubbing and stripping operations shall be separated from objectionable materials and spread within the road reserve or borrow areas, or otherwise disposed of, as approved or directed by the S.O.

2.1.2.4 Timber

The ownership of timber is vested in the Government. Saleable timber shall be trimmed and stacked in accordance with the requirements of the appropriate Government agency, in accessible places within the road reserve as approved or directed by the S.O.

The Contractor shall have the right to use unsaleable timber (or saleable timber when permission is granted in writing by the




appropriate Government agency or authority) for his own purposes in connection with the Contract, always provided that heshall comply with the requirements of the S.O. agency or authority) for his own purposes in connection with the Contract, always provided that heshall comply with the requirements of the S.O.

2.1.2.5 Structures

Major structures are those which cannot practicably be cleared by bulldozer and/or hydraulic excavator, whose demolition requires pneumatic tools, explosives and/or other specialised equipment. A brief description of each major structure (if any) and depth to which extent it shall be demolished is given in the Bill of Quantities.

All fences, buildings, structures, and encumbrances of anycharacter within the limits of the road reserve, except those to be removed by others or designated to remain, shall be demolished and removed by the Contractor.

Materials designated in the Contract or directed by the S.O. to be salvaged, shall be carefully removed and stored, and shall be the property of the Government.

2.1.2.6 Disposal Of Material

Unwanted material from clearing,grubbing and stripping topsoil (including the demolition of structures) shall be disposed of asapproved or directed by the S.O.

Combustible material including all timber (except timber to be salvaged or used), all brush, stumps, roots, vegetation and other combustible refuse may be piled up within the road reserve and burned, where burning is allowed.

All burning shall be subject to the prior approval of the relevant Government authorities, and shall be carried out in conformance with all pertinent regulations. Burning shall also be carried out at such places and at such times andin such a manner as to prevent fire from damaging vegetation and property within the road reserve designated to be preserved, and from spreading to areas adjoining the road reserve and damaging vegetation and property therein.

Should the clearing, grubbing and stripping of topsoil be carried out at a time when burning is not permitted, the Contractor may pile up combustible materials within the road reserve outside the limits of the road works, and burn it at a time when burning is permitted.

Where burning is not permitted at any time, or theContractor elects not to burnunwanted material, combustible material shall be disposed of together withincombustible material.




Incombustible material, includingwhere appropriate the remains of burning, shall be disposed of in a safe and tidy manner at solid waste dumps outside the Site, unless otherwise approved or directed by the S.O. The Contractor shall be solely responsible for making the necessary agreements, and payingexpenses and claims arising from the use of such solid waste dumps whether on Government or private land.

2.2 EARTHWORKS

2.2.1 Definitions

(a) Formation Level

Formation level means the top surface of the subgrade.

(b) Subgrade

Subgrade means that part of the embankment or existing ground in cutting which is immediately below the subbase or lower subbase of the road pavement and shoulders.

(c) Common Excavation

Common excavation shall mean excavation in any materials which are not rock or artificial hard materials as defined in Sub-Sections 2.2.1 (f) and (g).

(d) Unsuitable Materials

Unsuitable materials shall include :-

i) running silt, peat, logs, stumps, perishable or toxic material, slurry or mud, or

ii) any material

- consisting of highly organic clay and silt;

- which is clay having a liquid limit exceeding 80% and/or a plasticity index exceeding 55%;

- which is susceptible to spontaneous combustion;

- which has a loss of weightgreater than 2.5% on ignition;

- containing large amounts of roots, grass and other vegetable matter.

Materials that are soft or unstable merely because they are too wet or too dry for effectivecompaction are not to be classified as unsuitable, unless otherwise classified by the S.O.

(e) Suitable Materials

Suitable materials shall mean those materials other than the unsuitable materials defined in Sub-Section 2.2.1 (d) above.

(f) Rock

Rock shall mean material found in ledges or masses in its original position which would normally have to be loosened either by blasting or by pneumatic tools or,if excavated by hand, by wedges and sledge hammers. It shall not include material which can be loosened with a track-type tractorwith mounted and drawn ripper of the following descriptions :-




i) Tractor Unit : Equipment with a minimum weight of 20 tonnes and nett horse power rating of 200 brake horse power or more. The tractor unit is to be in good condition and operated by experienced personnel skilled in the use of ripping equipment;

ii) Ripping Unit : The ripper to be attached to the tractor shall be themost efficient parallelogram type recommended by the tractor or ripper manufacturer. The ripper shall have a single shank in good working condition with sharpened cutting point.

Boulders or detached pieces shall only be regarded as rock if they individually exceed 0.5 cubic metre.

(g) Artificial Hard Material

This shall mean any hard artificial material which would require the useof blasting or approved pneumatic tools for its removal but shall exclude individual masses less than 0.5 cubic metre.

2.2.2 General Requirements

The work shall include the excavation of all types of material, backfilling, compaction, forming embankments and slopes, etc., as is necessary for the completion of the Works up to the formation levels, inaccordance with the lines, grades, dimensions, shapes and typical cross- sections shown on the Drawings and to the approval of the S.O.

The Contractor shall provide where necessary temporary water courses, ditches, drains, pumping or other means of maintaining the earthworks free from water. Such provision shall include carrying out the work of forming thecuttings and embankments in such a manner that their surfaces have at all times a sufficient gradient to enable them to shedwater and prevent ponding.

In pumping out excavations and in the lowering of water tables the Contractor shall pay due regard to the stability of all structures.

Adequate means for trapping silt shall be provided on all temporary drainage systems. Similar arrangements shall be made for all earthworks including excavations whether for pile trenches, foundations or cuttings.

Should the surface of completed areas be damaged by erosion or by any other cause the Contractor shall at his own cost make good such areas to the satisfaction of the S.O.

The Contractor shall exercise care in preventing wastage of suitable material needed for embankment or fill construction.

2.2.3 Roadway Excavation

2.2.3.1 Dimensional Tolerances

Slopes in cutting shall be trimmed mechanically to neat and even surfaces which shall have gradients not steeper than that shown on the Drawings. Widths of excavations shall not exceed the dimensions shown on the Drawings by more than 300 mm, unless otherwise approved by the S.O.




2.2.3.2 Separation and Stockpiling of Suitable Material

Where excavation reveals a combination of suitable and unsuitable materials, the Contractor shall, wherever the S.O. considers it practicable, carry out the excavation in such amanner that the suitable materialsare excavated separately for use in the Works without contamination by the unsuitable materials. The Contractor shall stockpile separately material for subgrade as specified in Sub- Section 2.2.7.

2.2.3.3 Removal of Excavated Material From Site

No excavated material shall be removed from the Site except on the direction or with the approval of the S.O. Should the Contractor be permitted to remove suitable materials from the Site to suit his operational procedure, then he shall make good any consequent deficit of fill material arising there from, at his own expense. Unless designated dump sites have been shown on the Drawings, the Contractor shall dispose of surplus suitable material at his own dump areas outside the Site as approved by the S.O. In doingso, the Contractor shall comply with statutory requirements such as payment of royalties, environmental protection, etc.

2.2.3.4 Removal of Unsuitable Material

Unsuitable material shall beexcavated to such depth and over such area as directed by the S.O. and be transported and disposed of in an approved manner. Unlessapproval of the S.O. to dump andspread the unsuitable materials within the Site is obtained, the Contractor shall be responsible for providing his own dump site for such unsuitable materials. The Contractor shall comply withstatutory requirements such as payment of royalties, environmental protection, etc. Voids created due to removal of unsuitable material shall be backfilled with suitable material compacted to a dry density not less than that of the surrounding material or that specified for the respective part of the earthworks or as directed by the S.O.

2.2.3.5 Replacement of Unsuitable Material Under Standing Water

Where it is decided by the S.O. that replacement of unsuitable material shall be done under standing water, voids created due to removal of unsuitable material shall be backfilled with hard clean crushed rock, natural gravelor sand having grading within therespective limits specified in Table 2.1.

2.2.3.6 Widening Cuts

The S.O. may instruct the Contractor or the Contractor himself may elect to obtain material for the Works by widening cuts. In the latter case, the Contractor shall first request permission in writing from the S.O.




TABLE 2.1 - GRADING LIMITS OF MATERIALS FOR REPLACEMENT OF UNSUITABLE MATERIAL

Where the rock is of satisfactory quality, the Contractor may elect to crush and screen it to produce aggregates required for concrete, roadbase, subbase, or other purposes.Excavated rock needed for earthwork construction which the Contractor elects so to use for producing select materials shall be replaced at the Contractor's own expense by borrow of satisfactory quality approved by the S.O.

Otherwise, excavated rock shall be used in the construction of embankment and fill, to the fullest practical extent, in either of the two following ways :-

i) excavated rock shall be broken down to a maximum particle size of 400 mm and used as rock fill as described in Sub-Section 2.2.5;

ii) excavated rock shall be broken down to a maximum particle size of 150 mm, blended with suitableearth fill material in a proportion not exceeding 1 rock to 1 earth, and used as common fill.

The Contractor may only waste excavated rock with the approval of the S.O. Excavated rock needed for earthwork construction which the Contractor elects to waste shall be replaced at the Contractor's own expenseby borrow of satisfactory quality approved by the S.O.


B.S. Sieve Size

% Passing By

Weight

Crushed Rock or

Gravel

63.0 mm 37.5 mm 20.0 mm 10.0 mm

100 85 - 100 0 - 20 0 - 5

Sand

10.0 mm 5.0 mm

1.18 mm 300 um 150 um

100 90 - 100 45 - 80 10 - 30 2 - 10

2.2.3.7 Excavation of Rock

Rock excavation shall be carried out by methods appropriate to Site requirements as approved by the S.O. Where explosives shall be used, the relevant security regulations dealing with purchase, transport, handling, storage and usage of explosives shall be complied with.

All material from rock excavations shall be used as far as is practicable in the Works.



2.2.3.8 Storage and Handling of Explosives

Proper buildings or magazines, with separate compartments for detonators, in suitable positions for the storage of explosives in manner and quantities to be approved shall be provided. The prevention of any unauthorised issue or improper use of any explosivebrought on the Works shall bethe responsibility of the Contractor and only experienced and responsible men shall be employed to handle explosives for the purpose of the Works.

2.2.3.9 Blasting

Explosives shall be used in the quantities and manner recommended by the manufacturers. Blasting shall be restricted to such periods as the S.O. may prescribe. If, in the opinion of the S.O., blasting would be dangerous to persons or property or to any finished work, or is being carried on in a reckless manner, he may prohibit it, and order the rock to be excavated by other means. The use of explosives in large blasts, i.e. exceeding 9 kg of explosive, as in seams, drifts, shafts, pits, or large holes, is prohibited unless authorised in writing by the S.O. Such authorisation shall not in any way relieve the Contractor of his liabilities under the Conditions of Contract.

All necessary precautions shall betaken to preserve in the soundest possible condition the materials below and beyond the lines of all excavations. Delayed blasting to reduce shock waves shall be usedto avoid damage to concrete and other works already completed. As the excavation approaches its final lines, blasting shall be carried out by means of parallel drill holes perpendicular to the toe of the excavation and parallel to the finally required face.

2.2.3.10 Safety Measures

When blasting is carried out closeto properties or roads, appropriatesafety rules shall be strictly adhered to. Where necessary or as directed by the S.O., the use ofheavy mesh blasting mats shall be used to ensure that no damage is caused to persons or property on or off Site. Special care shall be taken in wet ground to ensure that individual explosions are reduced to such size as to preclude damage to any buildingsor structures. Plaster shooting will not be permitted within 400 metres of any building or structure. If traffic on any road or railway has to be interrupted for blasting operations, the Contractor shall obtain approval of his schedule for such interruption from the appropriate authorities and shall prove to the S.O. that he has obtained it, prior to the interruption.




2.2.3.11 Insecure Material

The slopes of cuttings shall becleared of all rock fragments which move when prised witha crow-bar. Where, in the slopes of cuttings, layers of rock and soft material alternate and the S.O. considers that the slope, immediately after dressing, will not permanently withstand the effect of weather, the Contractor shall excavate any insecure material to an approved depth and build up the resulting spaces with grade 15P/20 concrete or masonry using rock similar to the adjoining natural rock so as to ensure a solid face.

2.2.4 Earth Embankment

2.2.4.1 Material

Fill materials for use in forming embankments shall be the suitable material obtained from excavation in cuttings. Where the quantity of such materials is inadequate, the Contractor shall obtain suitable materials from the designated borrow pits or from his own borrow pits which have been approved by the S.O.

2.2.4.2 Borrow Pits

The Contractor shall be responsible for locatingborrow pits. Designated borrow pits shown on the Drawings only indicate to the Contractor potential areas for borrow. Whether the Contractor obtains materials from the designated or his own borrow pit, it shall be his responsibility to ascertain the suitability of the pit with respect to the quantity and quality of the materials, whichshall be subject to the approval of the S.O. The Contractor shall pay all necessary fees, taxes or royalties to the appropriate authorities and observe all relevant regulations. The Contractor shall keep the borrow pits free from pondingwater and the excavation neat and tidy and shall carry out necessary erosion protection measures as instructed by the S.O.

2.2.4.3 Placement of Fill Material

All fill materials shall be deposited in layers. The loosedepth for each layer of fill shall be determined from the trial compaction. Each layer shall extend over the full width of the fill area and shall be compacted in accordance with the requirements of Sub-Section 2.2.4.4. Each compacted layer shall be maintained at all times with a sufficiently even surface in order to drain away the sur face water.




Where embankment is to be constructed on ground with a cross-slope flatter than 1(vertical) to 10 (horizontal) but steeper than 1 (vertical) to 30 (horizontal), the foundation material, except where this is rock, shall be scarified to a depth of 100 mm, blended with embankment fill material and compacted as described in Sub-Section 2.2.4.4.

Where embankment is to be constructed against existing embankment or on ground with across-slope of 1 or more (vertical)to 10 (horizontal), the foundation shall be excavated in all materials(including hard rock) to form benches with horizontal and vertical faces from which construction of the embankment shallproceed. The benches shall be contiguous beneath the full width of the embankment, and shall be of a suitable width to accomodateconstruction equipment such as motor-graders, trucks, rollers, etc.Scarifying of the horizontal and vertical faces of the benches shallnot normally be required, and thematerial excavated in forming thebenches may normally be used asfill in the embankment as approved by the S.O.

2.2.4.4 Compaction

(a) General

All materials used in embankments and as fill elsewhere shall be compacted as soon as practicable after being placed and spread.

Compaction shall be undertaken to the requirements of this Section by plant approved by the S.O.All compaction requirements shall be controlled by means of field density measurement.

For compaction of embankment slope, the Contractor may either extend each compacted layer beyond the design slope surface by at least 600 mm and then trim back to the required slope angle, or he may employ a tow type roller to compact thesloping surface.

(b) Compaction Trials

The B.S. 1377 Compaction Test (4.5 kg rammer method) shall be used in determining the moisture versus density relation of soil.

The Contractor shall submit tothe S.O. for his approval the proposed method of compaction for each main type of material to be used in the embankment. This shall include the type of compaction plant for each type of material and the number of passes in relation to the loose depth of material to achieve desired compaction. The maximum compacted thickness for fill shall be limited to 300 mm unless otherwise approved by the S.O. The Contractor shall carry out field compaction trials, supplemented by any necessary laboratory investigations, as required by the S.O.




This shall be done by using the procedures proposed by the Contractor for earthworks and shall satisfy the S.O. that all the specified requirements regarding compaction can be achieved. Compaction trials with the main types of material likely to be encountered shall be completed before the works with the corresponding materials will be allowed to commence. Each trialarea shall be not smaller than 8 m x 15 m.

(c) Degree of Compaction

The whole of the embankment below the top 300 mm of the subgrade shall be compacted to not less than 90% (for cohesive material) or 95% (for cohesionless material) of the maximum dry density determinedin the B.S. 1377 Compaction Test(4.5 kg rammer method).

(d) Field Density Testing

Field density tests on each layer of compacted earth fill shall be carried out using the sand replacement method in accordance with B.S. 1377 or by using other means of testing of comparable accuracy approved by the S.O.

(e) Moisture Control

Each layer of earth fill shall be processed as necessary to bring its moisture content to a uniform level throughout the material, suitable for compaction. The optimum moisture content as determined by the B.S. 1377 Compaction Test (4.5 kg rammer method) shall be used as a guide in determining the proper

moisture content at which each soil type shall be compacted. Water shall be added, or the material aerated and dried to adjust the soil to the proper moisture content to obtain the required density. A satisfactory method and sufficient equipment as approved by the S.O. shall be used for the furnishing and handling of water.

If the natural water content of suitable materials is too high for the proper compaction to be carried out, the Contractor can either bring down the moisture content by aeration or drying or alternatively replace it withsuitable materials of compactable moisture range at his own cost.

2.2.5 Rock fill Embankment

Rock used in rock fill embankments shall be of maximumparticle size of 400 mm so that it canbe deposited in horizontal layers, each not exceeding 500 mm in compacted depth and extending over the full width of the embankment except for any specified external cover to slopes or new formation level. The materials shall be spread and levelled by a crawler tractor weighing not less than 15 tonnes. Each layer shall consist of reasonably well graded rock and all large voids shall be filled with broken fragments before the next layer is placed. The top surface and side slopes of embankments so formed shall be thoroughly blinded with approved fine graded material to seal the surface.




There shall be a transition layer between rock fill and earth fill or thetop 300 mm of subgrade of at least 300 mm compacted thickness. This shall consist of uniformly graded crushed rock between 6 mm and 150mm as approved by the S.O.

Each layer of rock used as rock fill in embankments shall be systematically compacted by at least 12 passes of a vibrating roller with a static load per 25 mm width of roll of at least 45 kg or a grid roller with load per 25 mm width of roll of at least 200 kg or other approved plant.

2.2.6 Embankment Over Soft Ground

2.2.6.1 Foundation Treatment

Prior to forming embankment over soft ground, the soil overwhich fill material shall be placed shall be given strength improvement treatment as specified and to the details as shown on the Drawings or as directed or approved by the S.O. Treatment by means of replacement of unsuitable material shall be as specified in Sub-Sections 2.2.3.4 and 2.2.3.5.

The first layer or layers of fill materials shall be deposited over the full width of the embankment and berms in thicknesses and compacted as approved by the S.O. The Contractor shall provide compaction plant suitable for working over soft ground.

2.2.6.2 Surcharge and Staged Construction

Where indicated in the Contract or directed by the S.O., the embankment shall be built todifferent heights in stages with or without surcharge with allowancefor consolidation time periods in between stages, all in accordance with the Contract. Where surcharge is specified, the Contractor shall be responsible for the provision of surcharge material and the removal and disposal of excess material on completion of consolidation or when directed by the S.O.

2.2.6.3 Settlement Markers

Markers shall be provided and installed by the Contractor in the positions indicated on the Drawings for the purpose of measuring settlements taking place under the embankments during and after the construction period. The design of markers shall be as shown on the Drawings and the Contractor shall be responsible for supplyingand installing such markers and for extending the markers as the work proceeds. Adjustments to the height of markers shall be made when required by the S.O. Each marker shall be identified by painting on it the chainage of its position.

The Contractor shall take all necessary measures to protect markers from damage by plant and vehicles at all times and shallrepair any such damage to the satisfaction of the S.O. Readily visible barriers shall be installed around each marker.




2.2.6.4 Settlement Records

Joint measurement of settlement shall be taken weekly while fill is being placed in the vicinity of the markers. Thereafter, readings shall be taken fortnightly for aperiod as directed by the S.O.The readings shall be submitted on an approved printed form to be supplied bythe Contractor.

For the measurement of the volume that has settled below the original level of the foundation of the embankment, the measured settlement of each marker shall be used for volume computation following the method shown on the Drawings.

2.2.7 Subgrade

Material for the top 300 mm of subgrade shall have a minimum California Bearing Ratio (CBR) as shown on the Drawings when compacted to 95% of the maximum dry density determinedin the B.S. 1377 Compaction Test (4.5 kg rammer method) under 4 days soaked condition.

Throughout the top 300 mm of subgrade, the material shall be compacted to not less than 95% (for cohesive material) or 100% (for cohesionless material) of the maximum dry density determinedin the B.S. 1377 Compaction Test(4.5 kg rammer method).

In cut area, the top 300 mm of the subgrade shall be scarified and recompacted to 95% (for cohesive material) or 100%

(for cohesionless material) of the maximum dry density determined in the B.S. 1377 Compaction Test (4.5 kg rammer method). If the S.O. is fully satisfied that the subgrade in its natural state possesses a density exceeding the requirements, then the surface of the subgrade shall be trimmed and rolled to obtain a smooth finish.

Where the material in cut area is found to be unsuitable for use in the top 300 mm of subgrade it shall be removed and replaced with suitable material which shall be compacted asindicated above.

The subgrade shall be finished in a neat and workmanlike manner, and the widths of embankments and cuts shall be everywhere at least those specified or shown on the Drawings on both sides of the centreline. The top surface of the subgrade shallhave the required shape, superelevation, levels and grades andshall be finished everywhere to within + 10 mm and minus 30 mm of therequired level.

i) Where rock surface extends over the whole width of the formation :-

The rock surface shall be trimmed to a free draining profile, at or below formation levels. No high spot shall protrude above the formation levels.

Any voids or cavities more than 0.5 metre below the formation level shall be filled up with approved lean concrete having 7-day cube strength greater than 7 N/sq.mm. The rock surface shall then be brought up to the formation levels with approved




crushed rock or gravel, regulated and blinded.

ii) Where rock outcrop occurs over part of the formation only:-

The rock outcrop shall be cut down to a level not less than 300 mm below the formation level. The surface shall then be brought up to level with suitable subgradematerial.

2.2.8 Protective Vegetation for Erosion Control

2.2.8.1 Topsoil

Topsoil stockpiled for the Works in accordance with Sub- Sections 2.1.1.3 and 2.1.2.3 shall be spreadand lightly compacted to an even thickness of 50 mm as directed by the S.O. in areas to be turfed and/or seeded, or used as the S.O.shall otherwise direct for tree planting and other purposes.

2.2.8.2 Turfing

Turfing shall be carried out as soon as practicable on all earth slopes and other areas as shown on the Drawings and/or where directed by the S.O. The type of turf shall be as indicated on the Drawings or other alternative type as approved by the S.O. andshall be free of lallang and essentially free of weeds.

Turf shall be obtained in unbroken sods with a substantial amount of topsoil and shall be approximately 250 mm x 250 mm in size and 100 mm thick, from an approved source, and shall be placed in position as soon as practicable after cutting.

Turf sods shall be stacked and watered when they cannot be laid immediately after cutting.

The surfaces to be turfed shall be trimmed and thoroughly wetted. The turf shall then be carefully laid to form a complete and uniform cover as shown on the Drawings. Turf laid on slopes steeper than 1 (vertical) and 3 (horizontal) shall be pegged down with bamboo stakes approximately 250 mm in length.Approved fertiliser shall be applied after placing of turf at suitable times and at rates of application approved by the S.O.

All turf shall be regularly watered and fertilised to the satisfaction of the S.O. until the vegetation is satisfactorily established. Any dead turf shall be replaced with new turf at the Contractor's own expense.

2.2.8.3 Seeding

Seeding or hydroseeding shall be carried out as soon as practicable on slopes and other areas as shown on the Drawings and/or directed by the S.O.

The Contractor shall submit to the S.O. for his consideration andapproval, at least four (4) weeks in advance of the proposed work, full details of his proposed method of seeding or hydroseeding. The information submitted shall include, but not necessarily be limited to, a full description of the following aspects of the work :-




i) the preparation of the areas to be seeded or hydroseeded, including if appropriate the amount of topsoil to be used and its method of application;

ii) the details and results of investigations to determine whichtypes of grass and legume are compatible with the soil in the areas to be seeded;

iii) the types of grass and legume (if any) and strains of seed to be used, and the function, root and growth characteristics of each type;

iv) the rates of application of the grass and legume seeds;

v) the composition of fertiliser to be used at the time of seeding and itsrate of application;

vi) the composition of fertiliser to be used after seeding, the times of application after seeding, and the rates of application;

vii) the type of mulch to be used and its method and rate of application;

viii) the amounts of lime or other chemicals (if any) to be applied to improve the soil before, during and/or after seeding;

ix) the type and amounts of binding agent to be applied with the seeds, mulch, fertiliser, etc., as appropriate.

x) the proportions and methods of preparation of the seeding mix;

xi) the equipment and methods to be used in preparing and placing the seeding mix and other materials;

xii) the cultivation and after-care of the seeded areas, including rates and frequencies of watering, fertilising, grass cutting and general maintenance for at least 1year after seeding;

xiii) the time after seeding required forestablishing permanent, dense growth of grasses, which will require minimal maintenance;

xiv) guarantees of the success of the seeding work.

All grass shall be regularly watered untilthe vegetation is satisfactorily established to the satisfaction of the S.O.Any dead grass shall be replaced at the Contractor's own expense.


section 2 earthworks

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