MATERIAL AND EARTH WORK SPECIFICATION

Borrow Material

Borrow material shall meet the requirement specified for satisfactory fill materials per ASTM D2487 or ASTM D2488 and shall be free from refuse, or other material that might prevent proper compaction or caused the completed backfill to have insufficient bearing capacity for the expected superimposed load.

Granular Bedding Material

Well graded sand, gravel, or manufactured aggregate containing no particles larger than 1/2 –inch (12.7 mm), and free from roots, debris, or any other substance that would harm the pipe or might impair the performance of the material as bedding for the pipe.

Sand

Sand shall be fine aggregate per ASTM C33.

Select Granular Backfill

Any soil classified per ASTM D2487 or ASTM D2488

EXECUTION

No grading and earth-moving shall start in any area until clearing, grubbing and stripping have been completed for that area. This works consists of clearing, grubbing and stripping of areas where excavation, filling to be done, including removal and proper disposal of unsuitable and waste materials removed during the operation. Before starting, erect protective barriers and after the work is complete, remove and dispose of them.

Clearing

Clearing includes removal and proper disposal of trees and downed timber, brush, hedges, bushes and other vegetation or organic materials and rubbish , debris , or other foreign or objectionable materials on or protruding through the surface areas to be cleared.

Grubbing

Grubbing including removal and disposal of stumps, large roots, buries logs other objectionable materials to 300 mm below ground surface.

Stripping

Stripping consists of removing of all rubbish, humus, vegetable matter and all or part of the organic topsoil in the respective areas which can be removed by simply excavation methods and to a depth as directed by Company. All borrow pit shall be stripped to a depth which allows for suitable material to be produced.

Topsoil Removal and Stockpiling

a. Topsoil is generally representative of agriculturally productive soil. Topsoil shall be free from subsoil and objectionable material that would hinder plant growth or maintenance and shall not contain more than 5% by volume of stones large than 25 mm.

b. Remove materials only to such depth that it meets the definition of topsoil. Strip and stockpile removed topsoil in areas to be excavated separately from other excavated materials. Protect topsoil stockpile from contamination during progress of the work until these materials have been used in finishing operation. Conserve acceptable topsoil from the site sufficiently to cover area requiring planting.

Disposal

Disposal areas shall be left with neat and acceptable appearance, graded surfaces and slopes assuring proper drainage.  Areas from which the materials will be used again shall be cleared of trees, stumps, roots down timber and other regression. The disposal shall be located where they will not interfere with the natural flow of construction operations.

In the borrow pit area the accessibility to the site shall be granted for the construction works. Excavated material designated to be reused to receive vegetation shall be separately disposed. The height of its heaps or stock piles shall not exceed 2 m, and not be driven over by excavating or transport equipment.

Fills and Embankments

Where the structure or pipeline is to be installed in an area of fill or embankment, verify that such work has been completed. 

Erosion, Sedimentation and Dust Control

Before starting earthwork operation on any particular area of the project site, install measures for the control, prevention, and abatement of erosion and sedimentation for that area is required. Schedule and conduct construction operation in such a manner and sequence that erosion, sedimentation, and dust on the project site is minimized. Coordinate the installation of temporary erosion control features with the construction of the permanent erosion control features to the extent necessary to ensure effective and continuous control of erosion throughout the period of work. Measure to control dusting including routine watering and seeding of stockpile soils. All erosion, sedimentation, and dust control facilities shall be installed as indicated on the drawing when required, checked after each rainfall and maintained in order to continue to perform efficiently.

Excavation Safety

Plan and assemble for materials and equipment required to stabilize excavation sidewalls as necessary to ensure the safety of personnel working in the excavation, and the protect existing facilities and structures in the vicinity of the work from damage. The systems, methods, and techniques used shall meet or exceed all applicable requirements of the OSHA Construction Industry Standards, and all other local codes and regulations. Barriers and warning devices shall be placed around the excavations, especially where excavations are unattended, to indicate a hazard exists, in the immediate vicinity.

Slope Stabilization

Stabilize the sides of excavations as necessary to prevent slope failure or any other earth movement that might injure personnel, or damage existing buildings, structures, or other facilities in the vicinity of the work. Earth retainers, such as shoring and sheet piling, shall be installed where required. The stabilization method employed shall comply with pertinent requirements of the OSHA Construction Industry Standards and other applicable local codes and regulations.

Removed sheeting, bracing, and shoring systems employed for slope stabilization as the progress of the work eliminates their need, unless they are permitted or required to remain by other provisions of these specifications or the other contract documents. Carefully remove such system in other to prevent subsidence or other soil movement that might damage existing or newly constructed structures or other facilities.

Existing or Complete Utilities

Carefully move machinery and equipment over existing or newly installed pipes and utilities during construction so as not to damage completed work. For work immediately adjacent to, or excavation exposing an existing utility or other structure, use manual or light equipment excavating techniques. Do not use power driven equipment to excavate closer than 2-feet (600 mm) from any existing utilities or structures. Support uncovered pipes and other existing work effected by the excavation until they properly supported by backfill. Report immediately any damage to utility lines other subsurface facilities.

Structures and Surfaces Condition

Protect newly backfilled areas and adjacent structures, slopes, or grades from damage. Repair and re-establish damaged grades and slopes. Protect existing streams, ditches, and other stormwater facilities from silt accumulation and erosion.

Control of Water

Prevent of control water flow into excavations, or water accumulation in excavations, to ensure that the bottom and sides of excavations remain firm and stable throughout construction operations.

Surface Water

Plan and conduct excavation operation so as to minimize the disruption of stormwater drainage in the vicinity of the work. Provide diversion ditches, dikes, and other suitable measure to control and direct runoff around and away from the excavation. Protect the sides of excavations from erosion and sloughing caused by stormwater runoff. Promptly remove stormwater accumulations in excavations. The system and equipment for controlling surface water shall be of sufficient capacity to accommodate the runoff rate expected from the 2-years (50 percent annual chance) rainfall event, with no significant disruption of the construction schedule, or damage to existing features or facilities in the vicinity of the work.

Ground Water

When the bottom of the excavation must be carried to an elevation below the groundwater piezometric surface, or to such proximity to the piezometric surface that the excavation bottom will become soft due to its being saturated by groundwater, take measures to lower the piezometric surface sufficiently to maintain the stability of the excavation bottom. Design the groundwater control system using accepted professional methods of design and engineering consistent with the best modern practice. The system shall includes trenches and sumps with pumps, well points, and such other equipment, appurtenances, and related earthwork necessary to achieve the groundwater control need the work. Carefully design and operate the system to avoid damage to existing structures and other facilities in the vicinity of the work.  

Disposal of Removed Water

Convey water removed by the water control system to an existing stormwater drainage facility that has sufficient capacity to accommodate the flow rates involved without damage. Secure permits or other approvals required from authorities having jurisdiction for such stormwater discharge. After completing construction operations needing water control, remove materials, equipment, and other facilities  used for that purpose, and clean up and restore affected areas as required.

Excavation, Backfill and Compaction

Remove soil, rock, and other materials as necessary to achieve the finish grades, sub-grades, or other limits of excavation indicated. Use satisfactory materials resulting from excavation work in the construction of fills and embankments, and for the replacement of removed unsuitable materials. After the excavation to the required finish grade is completed, re-compact materials that are to remain but have been loosened or otherwise disturbed by the excavation operations, to a firm, stable condition, and to a density equal to or greater than the surrounding undisturbed material.

Stockpiling and Disposal of Materials

Stockpile excavated satisfactory materials that are surplus to the quantity needed for construction of required fills and embankments, or for replacement of unsuitable. Stockpiles shall be neatly shaped and free draining, with sides sloped at 4 horizontal to 1 vertical or flatter. Dispose of excavated materials that are unsatisfactory for use as fill or are surplus to that needed for backfilling, in a safe and proper manner off the project site or in areas of the project site designated for that purpose.  

Rock Excavation

Remove rock encountered in areas requiring excavation using mechanical methods (such as ripping, wedging, or impacting) to reduce the rock to manageable sized fragments. Except as otherwise shown, required, or specified, excavate rock to a depth of no less than 300 mm below the indicated finished grade. Backfill undercut areas with satisfactory materials placed and compacted in accordance with requirements for fills and embankments. In areas to be paved, remove rock to a depth of no less than 75 mm below the pavement sub-grade surface. The remaining rock surface shall be free of projecting ribs or points, and shaped so that positive drainage of the surface is provided and no water will be pocketed at any point. Grout crevices in the surface with lean concrete. Backfill undercut areas with cohesion less, satisfactory material, placed and compacted in accordance with the requirements for fills and embankments.

Excavation, Backfill, and Compaction for Structure

Excavation pits for constructing cast-in-place concrete foundations, footings, and other structures to permit the placement of each monolithic element of the structure to the full width and length required with a full horizontal bed. If the excavation sidewalls are to be used to form the sides of the structure, take special care during excavation to secure a true surface conforming to the lines and dimensions indicated on the plans for the structure. Corners and edges of the excavation shall be true and square, not rounded or undercut.

Foundation Material Other than Rock

When the bottom of the foundation is to rest on an excavated surface other than rock, take special care to avoid disturbing the virgin soil at the bottom of the excavation, and to protect the soil from the changes in moisture content. To accomplish this, do not excavate the final 150 mm of material until just before the structure is to be placed. When the bottom of the excavation must be exposed for extended period of time, during which time inclement weather may damage It, lower the bottom of the excavation approximately 50 mm below the indicated bottom of the structure, and backfill the over excavated area with lean concrete.

Rock Foundation Material

When the bottom of the structure is to rest on rock or other unyielding material, clean the bearing surface of loose material, and cut to a firm, level bed that is stepped, keyed, or serrated.

Backfill and Compacted

a. As soon as practical after completing construction of the related structure, including expiration of the specified minimum curing period for cast-in-place concrete, backfill the excavation to restore the required finished grade. Backfill by placing and compacting satisfactory backfill material or select granular backfill material, when required, in uniform horizontal layers of no greater than 150 mm loose thickness.

b. Insofar as possible, place and compact backfill symmetrically about the structure to avoid the development of unbalanced earth pressure loads on the structure.

c. Do not place backfill around new cast-in-place concrete structures until the concrete has cured at least 3 days, or, when the backfill result in the development of unbalanced earth pressure loads on the structure, do not start backfill until the concrete has cured for at least 7 days or compressive strength test indicated the concrete has achieved more than 80 percent of its specified compressive strength.

d. Step excavation side slope with each layer of backfill to avoid the development of unnecessary loads against the structure caused by backfill wedging between the structure and the excavation sidewalls.

Excavation, Backfill, and Compaction for Underground piping.

Carefully excavate trenches to the minimum depths and widths necessary for installing the pipe line and associated appurtenances in accordance with the requirements of this specification, and the lines and grades indicated on the plans or elsewhere in the contract documents. In the pipe embedment zone, the trench sidewalls shall be either sloped sufficiently to prevent sloughing or cave-in, or shall be properly supported. Stockpile excavated materials in an orderly manner a sufficient distance from the trench sidewalls to avoid endangering the stability of the bank.

Unstable Grade

When soft, yielding, or otherwise unstable soil conditions are encountered at the required trench bottom elevation, over excavate the trench to a depth of no less than 300 mm below the required pipe bottom elevation, and backfill with granular bedding material. If conditions are so severe that over excavating and backfilling will not achieve a stable condition, notify engineer immediately so that appropriate corrective measure may be identified.

Unyielding Grade

Whenever rock, stone, masonry, or other hard, unyielding materials is encountered at or above the required trench bottom elevation, remove it to provide a clearance of no less than 150 mm below and on each side of pipes and associated fittings, valves, and other appurtenances. Backfill the over excavated area with granular bedding material.

Previous Excavation

In the event that the trench passes over a sewer or through any other previous excavation, carefully compact the bottom of the trench to a density equal to or greater than that of the native soil adjacent to the previous excavation. Perform this compaction carefully to avoid damaging the previously installed facility.

Excavation for Appurtenances

a. Excavation for pre cast manholes, catch basins, drainage inlets, and other similar structures shall be of sufficient size to permit proper placement of the structure in their intended positions, and to permit proper placement and compaction of backfilling around the structure after their placement. For cast-in-place appurtenances, excavation shall be of sufficient size to permit placement and removal of necessary formwork.

b. When concrete is to be placed against the bottom or sides of an excavation, take care not to disturb the native soils that the concrete bears against. Excavate to final line and grade before the concrete or masonry is to be placed. Remove loose or unstable materials. Clean rock of loose material and other debris, and cut to a firm and stable surface, remove loose or deteriorated rock and thin strata.

Bedding

After excavation reaches the required trench bottom elevation and any unsatisfactory subgrade conditions are corrected as specified, prepare the bottom of trench for placement of the pipe by spreading in the trench a layer of loose granular bedding material to attain a level just above the required grade of the outside bottom of the pipe.

Initial Backfill

Place and compact select backfill from the spring line of the pipe to the top of the pipe embedment zone in uniform horizontal lift of not over 150 mm loose thickness. Bring up the level of backfill uniform on opposite sides of the pipe along the full length of each pipe section. Take care not to damage the pipe or any protective coating it may have.

Final Backfill

Place and compact satisfactory backfill material in 200 mm maximum loose thickness lifts to restore the required finished surface grade. During final backfill for plastic or other non-ferrous pipelines (if any indication on the section drawing), install plastic marking tape above the pipeline at a depth 300 mm to 600 mm below the required finish grade.

Compaction

Except in areas of load bearing subgrade, compact final backfill composed of satisfactory materials from the original trenching to a density equal to or greater than that of the existing undisturbed material immediately adjacent to the trench. Where the excavated material is unsatisfactory for use as backfill and, therefore, imported material are used, compacted the backfill to no less than 92 percent of  maximum density at optimum moisture content (Standard Proctor density)   unless otherwise stipulated elsewhere in specification herein.

Ditches and Channels

Construct new and modified ditches, and channels to conform to the lines, grades, and cross sections indicated on the plans or otherwise required by the contract documents. Trim and dress roots, slumps, rock, and other foreign material exposed by the work to conform to the required surface. Do not over excavate.

Soil Improvement

Geosynthetic material to be used as soil improvement in existing soft ground or swampy areas.

The existing soil condition does not have enough bearing strength then if load applied to the soil it can result in settlement of the soil. Therefore the soil is not stable to support the structure to put above it

The purpose of soil improvement is to :

• Reduce the settlement of structures

• Improve the shear strength of soil and thus increase the bearing capacity of shallow foundation

• Increase the factor of safety against possible slope failure of embankments

• Reduce the shrinkage and swelling characteristics of soils.

Method and materials selected for the soil improvement shall be designed by the specialist engineer.

The selection of the right materials to be used and suitable selection of the implementation procedure are essential to the success of the method.

Geosynthetic materials shall meet the requirement specified for satisfactory soil improvement material per ASTM in tensile strength, grab strength, puncture resistance, elongation, thermal stabilization and ultraviolet ray resistance.

Combination of some methods (overlapping method between different type of geosynthetic materials) should be evaluated as an alternative as well.

The soil improvement shall be design for different soil condition such as soft soil (clay or silt) that have N value of the Standard Penetration Test (SPT) less than 4 or cohesionless granular (N <10) and swampy area

Design shall be conducted with taking into consideration at what type and the quantity of load above the soil. The load may be the rig, camp, facility, vehicle, depth of embankment,  etc.

Soil investigation is then carried out, consisting of Standard Penetration Test (SPT/ borehole) and Dutch Penetration Test (DPT). The purpose of soil investigation is to know the actual soil stratification at a given site, the laboratory test results of the soil samples obtained from various depths and the observations made during the construction of other structures built under similar condition

Fills and Embankments

a. Construct fills and embankments by placing and compacting satisfactory materials in successive. Uniform horizontal lifts of no greater than 200 mm (8-inches) loose thickness. Compact each lift to the specified density before placing materials.

b. Where the required finish grade has slope steeper than 1 vertical to 8 horizontal, overbuild the slope by no less than 600 mm (measured horizontally) and trim back to finish grade after compaction.

 

Fill Material

Material will also be selected preferentially to exclude the use of highly plastic clay soils classified as CH, by ASTM Specification D2487. Highly expansive (cracking) soil having an Activity value greater than 1.25, or a degree of expansion classified by ASHTO T258 as “Very High“ or “Extra High” , shall not be used as Fill Material. The activity value shall be measured as the ration Plasticity Index (ASTM D424) / Percent Clay Sizes (ASTM D422)

Large Rocks

Rocks exceeding the maximum size allowed in satisfactory fill material shall be incorporated into deep fills and embankments subject to the following size and depth limitations:

Depth below Finish Grade  (m)  Maximum size allowable    (mm)

0.90 – 1.50                                                    150

Over 1.50                                                      300

Fill Material Test

Prior to the commencement of will work fill material samples have to be taken from each source  to be tested in respect to :

Relative Density          - ASTM D2049

Moisture Content         - ASTM D2216

Grain size distribution  - ASTM D422

A set of three samples shall be taken for every 5000 m³ of homogeneous in situ material. Permeability test per ASTM D2434 have to be performed for previous fill material on the basis of one test for 2500 m³.

Compaction requirements and Moisture Control

a. Compact satisfactory fill material to a uniform dry density of no less than 92 percent (92%) of maximum density at optimum moisture content (Standard Proctor density)   unless otherwise stipulated elsewhere in specification herein.

b. The depth 1st layer, 2nd layer etc, is 30 cm of sub grade beneath structurally loaded areas such as road, slab and foundation shall be compacted not less than 95 percent of maximum density at optimum moisture content (Standard Proctor density).

c. Compact each layer to a firm, stable condition using vibratory or impact type compaction equipment suitable for the material and lift thickness and operated in accordance with manufacture’s instruction.

d. Adjust the moisture content as necessary to achieve a condition suitable for compaction. For cohesive materials. The moisture content at the time of compaction shall be within 2 percentage points of optimum.

e. When water must be added, distribute it uniformly over the surface of the layer, and thoroughly incorporate it into the soil to achieve a uniform distribution of moisture throughout the material. When the moisture content is excessive, defer compaction until the material has dried to suitable moisture content. 

f. The type of compaction equipment and number of passes to be achieved the required compaction degree have to be specified.

Compaction Test

The most suitable equipment for compaction shall be evaluated from a trial fill of about 50 m length of each type road. Variable to be considered in the fill are lift thickness and number of passes of the compaction device. The purpose of the trial fill is to determine the most suitable combination of lift thickness and number of passes to achieve the required degree of compaction.

The lift thickness shall not exceed 0.30 m if not otherwise approved.

The following test program shall therefore be carried out :

Lift thickness      Number of passes

       0.20 m         2, 4, 6, 8,   or more

       0.30 m         2, 4, 6, 8,    or more

The settlement shall be measured after each group of passes and plotted versus the number of passes and the lift thickness

Compaction Control

The required degree of compaction has to be controlled by field and laboratory test as follows :

Plate bearing test per ASTM D 1194 on top or previously fill and to layer. One test for every 5000 m² on each sub layer. Field density test using sand cone method per ASTM D1556. One test for every 5000 m² on each sub layer. Permeability test (drainage material) per ASTM D2434. One test for every 5000  m ² on each sub layer (25 cm).

Backfill of Culvert trenches

Backfill around culvert shall not be performed until culvert run have been bedded inspected and tested. Care shall be exercised in placing and compaction material around culvert to maintain the material approximately at the same level, not in excess of a 300 mm different, on both sides of the pipe, throughout and placing and comp-acting of the material.

Placing and compaction of material shall be performed simultaneously on both side of culvert in such manner as will prevent injurious side pressures on culvert Material shall be thoroughly compacted using hand operated power tampers until compacted is at least 600 mm above culvert. Self-propelled compaction equipment shall not be used above culvert until the compacted material has reached the 600 mm minimum. A flat bed is required for the bottom of a trench for culvert, granular material shall be provided for bedding to depth indicates on the approved drawings

Testing of Earthfilling

The frequency of test shall be adapted to the nature and the extend of the earth filling works.

the standard specification the moisture-density relationship determination for each type of soil encountered in the works. A sample of each soil type shall be maintained in glass containers for subsequent reference. Each container shall be labeled with sample number, maximum dry density, and optimum moisture content. A record shall be maintained which will provide information regarding the areas of the project in which each soil type is encountered. Maximum density and optimum moisture content for each soil shall be determined by the procedures stated by ASTM.   

The testing shall conduct a minimum of one in place density determination per 1250 m² of fill placed

The density determination shall be made at locations selected randomly. The density determination shall be made in accordance with ASTM designation D1556.

Other methods of determination of in-place density may be used, but in the event of dispute, the designated method shall be used as the compacted soil is less than the specified dry density, additional tests as required shall be taken to delineate the area having un-sufficient compaction. This area shall then be worked and/or re-compacted until the required specified density is obtained. Dry density test shall be determined in accordance with the procedures of approved standards.  

Tolerance

The finished surface level shall be free of irregularities and depressions and shall have tolerance of ± 5 cm. In areas where roads are to be placed, the tolerance is limited to + 5 cm in case of excavation and - 5 cm in case of earth fill and the top of the sub grade shall be of such smoothness that when test with a 4 meter straightedge it shall not show any deviation in excess of 2.5 cm or shall not be more than 2.5 cm from grade as established by grid hubs or pins. Any deviation is access of this amount shall be corrected by loosening, adding or removing materials, reshaping and re-compacting by moistening and rolling.     

Site Restoration

After completing backfill placement and compaction, restore or replace shrubbery, turf, fences, and other features, surfaces, and structures disturbed during the work except as otherwise indicated. Return restored features and facilities to a condition equal or superior to that which existed before the work.

Finish Grading

At the completion of all construction work, the site shall be graded to provide for the runoff of surface drainage without trapping and pounding water. Trim and finish grade the surface of areas involved in work covered by this specification. The resulting surface shall be reasonable smooth and free of ruts, ridges, depressions, and other significant irregularities. Leave areas designated to be grassed  in a condition suitable for subsequent top soiling, and seeding or sodding operations.

Clean Up

Remove off the jobsite and properly dispose of surplus piping materials, soils, temporary structures, and other debris resulting from the work. Leave the site in a neat and clean condition, ready to receive topsoil, seeding, or whatever final surface treatment is indicated.