technical specification clayton road landfill stage 2 · construction quality assurance plan (cqa...

Prepared for: Clayton Road Landfill Joint Venture PO Box 5133 Clayton Vic 3168

Technical Specification

Clayton Road Landfill Stage 2

ENSR Australia Pty Ltd (ENSR) 27 October 2008 Document No.: M60049601_TechSpec_27Oct08.doc

Use or disclosure of data contained on this sheet is subject to the restriction on the distribution page of this document.

October 2008 Technical Specification

Commercial in Confidence M60049601_TechSpec_27Oct08.doc

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Technical Specification i October 2008

M60049601_TechSpec_27Oct08.doc Commercial in Confidence

CONTENTS 1.0 INTRODUCTION.........................................................................................................................1

1.1 Cell Location and Size.................................................................................................1 2.0 EARTHWORKS..........................................................................................................................3

2.1 General Bulk Out .........................................................................................................3 2.2 Subgrade Filling...........................................................................................................3

2.2.1 Soft Spot Rectification..................................................................................3 2.3 Compacted Clay Liner .................................................................................................3 2.4 Clay Liner Material Compliance Testing......................................................................4 2.5 Construction of Base Liner and Wall Liner ..................................................................4 2.6 Testing Requirements .................................................................................................4

2.6.1 Testing Frequencies.....................................................................................5 2.6.2 Procedures for Reworking Failed Areas ......................................................5 2.6.3 Procedures for Placing and Compacting Clay Liner ....................................5

2.7 Anchor Trenches .........................................................................................................6 2.8 Tolerances ...................................................................................................................6 2.9 Survey..........................................................................................................................7

3.0 GROUNDWATER RELIEF SYSTEM .........................................................................................9 3.1 Trenches......................................................................................................................9 3.2 Pipe Installation & Backfill ...........................................................................................9 3.3 Groundwater Sumps....................................................................................................9 3.4 Survey........................................................................................................................10

4.0 GEOSYNTHETIC CLAY LINER...............................................................................................11 4.1 Materials Specification...............................................................................................11 4.2 CQA of GCL...............................................................................................................11

4.2.1 Manufacturer’s Report................................................................................11 4.2.2 GCL Roll Information..................................................................................12 4.2.3 Handling and Storage ................................................................................12

4.3 GCL Installation .........................................................................................................12 4.3.1 Underlying Surface.....................................................................................12 4.3.2 Panel Placement ........................................................................................12 4.3.3 GCL Jointing...............................................................................................13 4.3.4 GCL Repair ................................................................................................13

5.0 GEOMEMBRANE LINER .........................................................................................................15 5.1 Materials Specification...............................................................................................15

5.1.1 Geomembrane ...........................................................................................15 5.2 CQA of Geomembrane..............................................................................................16

5.2.1 Manufacturer’s Report................................................................................16 5.2.2 Third Party CQA Representative................................................................16 5.2.3 Geomembrane Roll Information .................................................................17 5.2.4 Handling & Storage ....................................................................................17

5.3 Geomembrane Installation ........................................................................................17 5.3.1 Underlying Surface.....................................................................................17 5.3.2 Panel Placement ........................................................................................17


October 2008 ii Technical Specification


5.4 Geomembrane Welding Methods..............................................................................18 5.4.1 Primary Weld Requirements ......................................................................18 5.4.2 Secondary Weld Requirements .................................................................18 5.4.3 Geomembrane Weld Preparation ..............................................................18 5.4.4 Weld Overlap..............................................................................................19

5.5 Geomembrane Repair ...............................................................................................19 5.5.1 Patches ......................................................................................................19 5.5.2 Capping ......................................................................................................19 5.5.3 Repairs via Extrusion Weld ........................................................................19

5.6 Weather Restrictions for Welding ..............................................................................20 5.7 Construction Quality Assurance Testing on Field Welds ..........................................20

5.7.1 Trial Welds .................................................................................................20 5.7.2 Non Destructive Testing.............................................................................20 5.7.3 Destructive Testing ....................................................................................21 5.7.4 Procedures for Failed Destructive Tests....................................................22

6.0 CUSHION GEOTEXTILE..........................................................................................................25 6.1 Materials Specification...............................................................................................25 6.2 CQA of Cushion Geotextile .......................................................................................25

6.2.1 Manufacturer’s Report................................................................................25 6.2.2 Handling & Storage ....................................................................................26

6.3 Cushion Geotextile Installation ..................................................................................26 6.3.1 Underlying Surface.....................................................................................26 6.3.2 Panel Placement ........................................................................................26 6.3.3 Cushion Geotextile Jointing .......................................................................27 6.3.4 Cushion geotextile Repair ..........................................................................27

7.0 LEACHATE COLLECTION SYSTEM ......................................................................................29 7.1 Materials Specification...............................................................................................29

7.1.1 Leachate Collection Pipes..........................................................................29 7.1.2 Leachate Drainage Aggregate ...................................................................29

7.2 Leachate Collection System Installation....................................................................30 7.2.1 Pipe Placement ..........................................................................................30 7.2.2 Leachate Collection Sump Construction....................................................30 7.2.3 Pipe Welding ..............................................................................................30 7.2.4 Leachate Drainage Blanket Construction ..................................................30 7.2.5 Geotextile Fabric Filter Layer .....................................................................31 7.2.6 Side Wall Leachate Drainage Layer...........................................................31

7.3 Tolerances .................................................................................................................32 7.4 Survey........................................................................................................................32


Technical Specification iii October 2008


TABLES

Body Report

Table 1: GCL Material Properties................................................................................................ 11 Table 2: Geomembrane Material Properties ............................................................................... 15 Table 3: Geomembrane Trial Weld Verification .......................................................................... 20 Table 4: Base Cushion Geotextile Material Properties ............................................................... 25 Table 5: Side Wall Cushion Geotextile Material Properties ........................................................ 25 Table 6: Side Wall Leachate Drainage Layer Material Properties .............................................. 31

FIGURE Figure 1: Site Location Plan


October 2008 iv Technical Specification




Technical Specification 1 October 2008


1.0 INTRODUCTION

1.1 Cell Location and Size This Technical Specification (Specification) has been prepared for the design and construction of Stage 2 at Clayton Road Landfill Joint Ventures (CRLJV) Clayton Road Landfill, Clayton South, Victoria (the Site) and has been developed in accordance with Environment Protection Authority Victoria (EPA) Best Practice Environmental Management Guidelines for Siting, Design, Operation and Rehabilitation of Landfills (BPEM).

The Site is located at crown allotment 654 Clayton Road, Clayton South, Victoria. The Geographical Information System (GIS) coordinate of the Site centroid in longitude and latitude (decimal degrees) coordinates in the 1994 Geocentric Datum of Australia (GDA94) is 145.116735 and 37.953165, respectively.

Stage 2 is located near the south eastern corner of the Site and is bound by Deals Road to the east, the existing Stage 1 and current landfilling area to the west, the existing completed landfill area to the north and the Site boundary to the south.

The base footprint of the new Stage 2 s approximately 1.3 ha. The cell will provide the CRLJV with approximately 1,000,000 m3 of airspace when combined with the remaining Stage 1 filling area.

Refer to Figure 1 for the Site Layout Plan.

This Specification provides details of specific construction requirements that should be undertaken during the construction of Clayton Road Landfill, Stage 2 and shall be used in conjunction with the construction Design Drawings and Construction Quality Assurance Plan dated August 2008. Should there be any discrepancy between the documents, ENSR shall be notified immediately for clarification, prior to works on the disputed item commencing.

The head Contractor (the Contractor) shall conduct all works in accordance with this Specification, the Construction Quality Assurance Plan (CQA Plan) and the Design Drawings (the Drawings). The Contractor shall develop a construction occupational health and safety system specific to these works and in accordance with all relevant statutory and regulatory requirements and shall ensure all works comply with such requirements. The Contractor shall make no additional claim or variation for changes to work methods that may be required to comply with the occupational health and safety system requirements.

Should there be any discrepancy between this Specification, the CQA Plan and or Drawings, ENSR shall be notified immediately for clarification prior to continuing with the construction works.


October 2008 2 Technical Specification






2.0 EARTHWORKS

2.1 General Bulk Out The subgrade shall be founded by the excavation of the insitu material within the cell footprint area. The excavated material is expected to generally consist of sand and clayey sand material. The subgrade base shall be formed in accordance with the requirements of this specification and to the levels outlined in the Design Drawings.

2.2 Subgrade Filling Where required, subgrade fill material may be placed to achieve the required design levels. Subgrade fill shall be placed in compacted nominal layers thickness of 250 mm. All subgrade fill shall be compacted to achieve a minimum dry density ratio of 90% Standard or a Hilf density ratio of 90% Standard in accordance with AS1289. The compacted subgrade fill shall be tested at frequency not less than 1 test per 500 m3 or 1 test per lift, whichever requires more tests.

In place of filling the subgrade areas with local fill material to reach the design levels, the Contractor may opt to increase the depth of the clay liner in such areas by installing clay liner material in accordance with the clay liner requirements of this Specification.

2.2.1 Soft Spot Rectification Where soft spots in the subgrade are encountered, the Contractor shall excavate out the area to a minimum depth of 1 m (or to a depth such that the soft regional is removed). The excavated area shall be replaced with clay, engineered fill or other approved local material to reach the subgrade design levels and compacted and tested in accordance with the requirements outlined in Section 2.2.

2.3 Compacted Clay Liner A compacted clay liner (CCL) of 1 m minimum thickness shall be constructed over the subgrade base and for side walls to the extents shown on the Design Drawings. The construction of all CCL works shall be accompanied by Level 1 Geotechnical Testing as set out in Appendix B of AS 3798-1996 Guidelines on earthworks for commercial and residential developments. All samples taken shall be tested by a National Association of Testing Authority (NATA) registered soils testing laboratory and the results of all compaction testing shall be documented within the GTA’s final report.

This entails, but is not limited to, full time testing and inspections of all clay liner works by the Geotechnical Testing Authority (GTA) who has been appointed by the Principal. The cost of the GTA works required by this Specification are covered by the Principal, however the Contractor shall bare the cost of all failed tests and re-testing of materials as required by the GTA to provide compliance with this Specification. The Contractor shall note that the Principal may recover these costs by a reduction in the Contractors progress payments during the construction works.

It is also noted that a laboratory test result lead time of 24 hours is expected for the results of field density testing for the compacted clay liner. It is the Contractors responsibility to ensure that the placement and compaction works are staged in such a manner that allows the installation works to continue whilst awaiting laboratory test results. The Contractor may, at their risk, continue installation works over a tested area based on the field data, prior to receiving the laboratory test results. Should the laboratory test result record a non-compliance the Contractor shall repair the failed area in accordance with the requirements of this Specification at the Contractors expense.

No cost variation or extension of time claims shall be made by the Contractor for variations in relation to the works undertaken by the GTA.




2.4 Clay Liner Material Compliance Testing All material that is to be used to construct the clay liner for the base liner, wall liner and bunds shall satisfy the following criteria:

• The material shall be free of rock greater than 50 mm in any direction.

• The material shall be generally free of topsoil, organic soil and root matter.

• The material shall not have less than 70% by dry weight passing the 19 mm sieve size.

• The material shall not have less than 30% by dry weight passing the 0.075 mm sieve size.

• The plasticity index of shall not be less than 10%.

• The Cation Exchange Capacity (CEC) shall not be less than 10 mEq/100g.

• When remoulded to a dry density ratio of 95% Standard at Standard Optimum Moisture Content (SOMC) have a co-efficient of permeability, measured in a triaxial cell, of no greater than 1 x 10-9 m/sec. Maximum Permeability of the material shall be 1 x 10-9 m/sec.

Testing of the material for compliance with the above properties shall be conducted by the GTA at a NATA registered soils testing laboratory and be conducted at a frequency not less than 1 test per 5 000 m3. Testing of the material for compliance shall be undertaken prior to its use within the cell construction and all results shall be submitted to the Auditor for approval.

Additional tests may also be undertaken during construction, within the cell, at the discretion of the GTA, should a visual change in the material be observed, or where the GTA deems necessary. At the completion of all earthworks, the GTA shall provide a Level 1 testing report to fully document the works undertaken to complete the earthworks, including all NATA testing results and provide certification that the works have been undertaken in accordance with this Specification.

2.5 Construction of Base Liner and Wall Liner The clay liner material shall be placed and compacted to achieve a clay liner of minimum thickness of 1 m in a minimum of four successive (250 mm thick nominal) layers, and each layer shall be compacted and tested to the requirements of this Specification.

2.6 Testing Requirements • Moisture Content Limit – Base: Greater than the Optimum Moisture Content

(OMC) for Standard Compactive Efforts (AS1289.5.1.1) and less than 6% (wet) above the OMC.

• Moisture Content Limit – Side Walls: Greater than the OMC for Standard Compactive Efforts (AS1289.5.1.1) and less than 4% (wet) above the OMC.

• Dry Density Ratio: Greater than 95% of the maximum dry density achieved in the Standard Compaction Test or a Hilf Density ratio of 95% in accordance with AS1289.

• Maximum Permeability: Insitu permeability tests shall be undertaken on the CCL to verify that the liner has achieved a maximum permeability of 1 x 10-9 m/sec.




2.6.1 Testing Frequencies Field testing for density and moisture content testing of all CCL shall be conducted at frequency the greater of the following:

• 1 test per 500 m3; or

• 1 test per clay base liner lift.

• 1 test every second clay wall liner lift.

• Field permeability testing, taken from the insitu CCL, shall be undertaken at the rate of 1 test for every 3 000 m3 of clay liner placed and shall be taken within the base and side wall liners.

• All testing shall be distributed evenly over the clay liner as determined by the GTA.

2.6.2 Procedures for Reworking Failed Areas If after testing the required moisture content has not met the above requirements of this Specification the failed area(s) shall be reworked as follows:

• The failed layer or area shall be tyned/ripped using the teeth of an excavator bucket or similar method approved by the GTA and additional moisture may be applied or the clay may be worked to allow for drying as necessary. Upon completion of these works the area shall be recompacted until the area is deemed suitable for retesting.

• Where it is necessary to increase the moisture content of the layer or area(s), watering by spraying with an approved sprayer (i.e. water truck or equivalent approved by the GTA) shall be undertaken.

• If after retesting the moisture content within the layer has still not met the requirements of this Specification then the above procedures shall be repeated until the GTA is satisfied that the requirements have been achieved. The GTA, at their discretion, may deem that the material is unsuitable for further moisture conditioning and the layer shall be removed and replaced with clay from the stockpile.

If after testing the required dry density has not met the requirements of this Specification the failed layer or area(s) shall be reworked as follows:

• The failed layer or area(s) shall be recompacted to increase the density until the area is deemed suitable for retesting.

• If after retesting the density within the layer has still not met the requirements of this Specification then the above procedures shall be repeated until the GTA is satisfied that the requirements have been achieved. The GTA, at their discretion, may deem that the material is unsuitable for further compaction and the layer shall be removed and replaced with clay from the stockpile.

2.6.3 Procedures for Placing and Compacting Clay Liner The clay liner material shall be hauled to the works area for spreading and compacting to form the clay liner. Following loose spreading, the clay liner material for each layer should be broken up to ensure that the clod sizes are not greater than the compacted layer thickness.

Prior to the placement of each layer, the top of the previously completed layer shall be thoroughly scarified to join each layer together and to prevent laminations at the layer interfaces. The scarification works may be undertaken by ripping the layer surface with the teeth of an excavator bucket or from retaining the compacted puck marks from an approved roller (such as, sheeps foot penetrating roller or CAT815 compactor) to the satisfaction of the GTA. If the surface of a previously placed and compacted




lift has been left for greater than 5 hours, and deemed necessary by the GTA, the affected layer shall be conditioned by tyning/ripping moisture conditioning and recompacting the layer surface.

Upon completion of the final layer of CCL to form the minimum 1 m thickness, the finished surface shall be worked to form a smooth surface in accordance with the Design Drawings. In order to limit cracks from forming in the surface the finished top of clay surface shall be kept moist, to the satisfaction of the GTA. Where a water truck is used to distribute water over the surface, any resultant wheel ruts shall be removed to the satisfaction of the GTA. Where cracks wider than 10 mm occur, the affected area(s) shall be reworked to the satisfaction of the GTA.

Where necessary and where indicated on the Drawings, the CCL shall be connected (keyed in) into the existing base liner, side liner and bund liner from the existing Stage 1 west.

All key in works shall consist cutting a minimum of 1 m into the existing clay liner to expose a fresh face of clay at an approximate 1(v) to 1(h) slope. During the placement of each layer, a 250 mm wide by 250 mm deep bench shall be cut into the face to allow layer connection between the new and existing liner to the satisfaction of the GTA.

2.7 Anchor Trenches Anchor trenches shall be constructed at the top of walls and bunds in accordance with the requirements shown on the Design Drawings.

The trenches shall be excavated to a minimum width of 300 mm to a depth of 500 mm using an excavator fitted with a trench bucket or similar approved equipment. Upon construction of the trench, the edges shall be rounded and any stones, debris and other sharp objects shall be removed from the trench. Trenches shall not be excavated more than two days prior to lining of the area, should any water be captured within the trench it shall be removed by pumping or other approved method. All trenches shall be inspected and be to the satisfaction of the Third Party CQA Consultant (refer Section 4.2.2) prior to commencement of lining.

During the installation of the geosynthetic liner system each geosynthetic element shall be extended (where appropriate) into the trench, temporary securing of the material within the trench may be conducted via the use of sandbags or from partial filling with approved compacted backfill material.

Upon completion of the geosynthetic liner system, the anchor trench shall be backfilled using the excavated clay liner material. Backfilling shall be conducted in a minimum of two layers and each layer shall be compacted via the use of a hand held wacker packer or similar approved equipment. Dry or desiccated clay shall not be used as backfilling material, should the excavated clay material become dry, then moisture conditioning of the material shall be undertaken or fresh clay from the source stockpile shall be used.

2.8 Tolerances The following tolerances for the CCL shall be as follows:

• The overall 1 m clay liner thickness shall have a tolerance of -0 mm up to +100 mm unless additional layers have been installed and testing has been undertaken to verify that the nominal layer thickness of 250 mm has not been exceeded.

• The grading of the base of the cell is the minimum average grade as shown on the Design Drawings.




2.9 Survey Upon completion of the subgrade and CCL works, the finished surfaces shall be surveyed by a licensed surveyor.

The surveyor shall be appointed by the Contractor and all costs associated with completing the survey works required by this Specification and to the satisfaction of the Superintendent, (including preparation of all plans and modelling) shall be borne by the Contractor.

The as-constructed drawings prepared by the surveyor shall show the following:

• the top of subgrade base and wall levels and grades;

• the groundwater relief trench alignment;

• the excavated groundwater collection sump base and wall levels;

• the top of the groundwater collection sump aggregate;

• top of clay levels and grades for base and walls;

• the clay liner base thickness perpendicular to the subgrade;

• the clay side wall liner thicknesses perpendicular to the subgrade (using cross sections);

• the leachate collection sump clay liner base and side wall levels thickness; and

• the anchor trench locations.




3.0 GROUNDWATER RELIEF SYSTEM

The groundwater relief system shall be generally installed to the locations and grades shown on the Drawings to obtain a maximum grid pattern of 20 m x 20 m. Where necessary, the grid spacing may be decreased or additional lines installed and connected to the groundwater relief system to capture isolated groundwater seepage zones within the subgrade.

3.1 Trenches The groundwater relief system shall be installed within the subgrade base by excavating trenches to a nominal width of 300 mm and depth of 500 mm.

3.2 Pipe Installation & Backfill The groundwater relief pipes shall be a minimum 100 mm diameter (Ø) slotted poly vinyl chloride (PVC) pipes and all junctions shall made using solid wall fittings. The trenches shall be filled with 50/20 mm aggregate and shall be fully enclosed within Bidim A12 (or approved equivalent) comprising of a non-woven needle punched geotextile fabric.

The 50/20 mm aggregate within the groundwater relief grid trenches shall be:

• Free draining;

• The aggregate shall not contain more than 1% fines;

• Free of organic or other deleterious material such as limestone or other calcareous material that may be subject to chemical attack; and

• Competent, and not deform or crush under loading;

Care shall be taken to preserve the correct alignment of the pipe and to avoid damage to pipe and fittings. The Bidim A12 geotextile fabric material shall be overlapped at the top of the aggregate in the trench as to fully encapsulate the 50/20 mm aggregate drainage material. The geotextile fabric shall be stapled at the overlap before the placement of any other overlying materials. A geotextile fabric overlap of 200 mm shall be maintained along the top of the trenches. If required an additional length of geotextile fabric may be stapled to the top of the trench provide the necessary overlap.

3.3 Groundwater Sumps Two forms of groundwater relief sumps will be utilised within Stage 2, these sumps are referred to as a Groundwater Collection Sump (GCS) and a Groundwater Extraction Sump (GES).

The GCS Sump shall be installed beneath the footprint of the Leachate Collection Sump at the low point of the cells valley line to the levels and grades shown on the Drawings.

The GCS shall be excavated within the subgrade base and upon excavation it shall be lined with geotextile fabric (Bidim A12, or approved equivalent) and filled with 50/20 mm aggregate to a nominal depth of 500 mm in accordance with the requirements of this Specification and the Drawings.

Prior to filling the GCS with aggregate, a 225 mmØ PVC perforated pipe shall be installed along the base of the GCS as shown in the Drawings. A 225 mmØ PVC solid wall pipe shall then be connected to the perforated pipe and installed within a trench from the GCS and into the GES as shown on the Drawings. All PVC pipe connections shall be conducted using solvent welding in accordance with the pipe manufactures instructions.




The GES has previously been constructed as part of the Stage 1 west works and is located at the south western edge of Stage 2.

The GES construction consisted of an excavation of approximately 4.5 m in depth and filled with free draining brick rubble and broken concrete. A 300 mmØ SN8 Black MAX riser pipe, perforated around the pipe length within the GES was installed from the base of the GES excavation to the top of the south wall as shown on the Drawings. This existing riser pipe was trenched within the south wall subgrade face to allow groundwater extraction from the GES.

Prior to connection of the GCS to the GES, the Contractor shall confirm the suitability of the existing GES extraction riser pipe for the installation of an electric pump and all associated pumping infrastructure required to extract groundwater from the GES. Should the Contractor consider the existing extraction riser pipe un-suitable the following works shall be undertaken:

• Extend the width of the existing GES to the east via excavation works.

• Excavate a 700 x 700 x 700 mm (approximate) trench within the southern side wall subgrade surface to enable the installation of a new 600 mmØ extraction riser pipe.

• The new extraction riser pipe shall be of High Density Polyethylene (HDPE) PN8 or polypropylene SN8 (Black MAX or equivalent) in type.

• The riser pipe shall be installed within the trench and extend into the widened area of the GES sump with the lower length perforated in accordance with the details shown on the Drawings.

• The widened GES area shall be filled with 50/20 mm aggregate and the top covered with geotextile fabric.

It is the responsibility of the Contractor to ensure that groundwater extraction works are undertaken from the GES during the entire life of the construction works, including sourcing appropriate pumps, operation and maintenance. The extracted groundwater shall be discharged into the existing pond nominated by the Superintendent.

No cost variation or extension of time claims shall be made by the Contractor for variations in relation to the works required to undertake the groundwater extraction from within the cell area.

3.4 Survey Upon completion of the groundwater relief system, the grid alignment and the top of the GCS shall be surveyed by a licensed surveyor. As built drawings shall be prepared and submitted to show location of the groundwater relief system over the cells subgrade base.




4.0 GEOSYNTHETIC CLAY LINER

All geosynthetic clay liner (GCL) covered by this Specification shall meet the minimum properties set out in this Specification and shall be reinforced and comprising of a woven and non-woven cushion geotextile fully needle punched together to contain Bentonite in granular or powder form. Glued or stitched GCL shall not be approved for construction under this Specification.

4.1 Materials Specification All GCL (X2000 approved equivalent) covered by this Specification must comply with the following requirements:

Table 1: GCL Material Properties

Material Property Test Method Units Value Testing Frequency

1. CBR Strength ASTM D3706.4 N ≥ 2 500 1 per batch

2. Bentonite Mass @ 0% Moisture ASTM D5993 g/m2 ≥ 3 700 1 per batch

3. Wide Width Tensile Strength ASTM D4595 kN/m ≥ 10 (MD) ≥ 25 (XMD)

1 per batch

4. Wide Width Tensile Elongation ASTM D4595 % ≥ 100 (MD) ≥ 70 (XMD)

1 per batch

5. Permeability ASTM D5887 m/sec ≤ 5 x 10-11 1 per batch

6. Cover Non Woven Geotextile Mass AS 3706.1 g/m2 ≥ 270 1 per batch

7. Carrier Geotextile Mass AS 3706.1 g/m2 ≥ 380 1 per batch

8. Swell Index AS D5890 mL/2g ≥ 24 Index test only

4.2 CQA of GCL 4.2.1 Manufacturer’s Report The manufacturer’s certificate of conformance (minimum level 3, or equivalent) shall be submitted with the GCL product delivered to Site which outlines the results for each property listed at the frequencies shown in Table 1.

No materials will be accepted for delivery to Site, or payment made, unless all necessary Manufacturer’s Quality Assurance certification data, as outlined in Table 1, has been provided to the Principal. All necessary data must be supplied in sufficient time, which includes time for review and approval of all information, such that no delay shall be caused to the project program.

If the submitted material is found to be nonconforming according to the limits detailed in the Specification by the Third Party Construction Quality Assurance (CQA) Consultant (TPCC) (refer Section 5.2.2), Superintendent or Auditor preventing acceptance of the material, the Contractor must undertake independent testing of the material for the properties listed in Table 1 at a laboratory approved by the TPCC and Auditor. The resulting cost of all materials retesting required shall be borne by the Contractor and no cost variation or extension of time claims shall be made by the Contractor for variations in relation to such works.




4.2.2 GCL Roll Information All GCL rolls shall be clearly labelled with the following information:

• GCL Roll Number;

• Product Type (i.e. X2000);

• Roll Dimensions; and

• Manufacturer’s Name.

The above information shall be recorded in a GCL placement log, and each installed panels given a unique number which shall cross reference to the as built drawings.

4.2.3 Handling and Storage All GCL delivered to Site must be individually packaged with weather resistant wrapping; all packaging must be intact with no signs of damage. Any damaged rolls shall be inspected by the TPCC and the Principal to assess any premature hydration of the rolls. The Principal in consultation with the TPCC may at their discretion reject any rolls that are deemed have a moisture content greater than 50% by weight upon their arrival to Site.

A dedicated storage area shall be selected on-Site that is away from high traffic areas and is on a level dry, well drained area of ground. The Contractor shall make provision for chocking blocks to prevent sliding or rolling of the stacks.

4.3 GCL Installation 4.3.1 Underlying Surface The GCL shall be placed above the finished (subgrade or clay) surface or as per the general locations indicated on the Drawings

The finished surface is a nominated hold point and no GCL shall be installed until at least one inspection of the finished surface has been undertaken by the Auditor and the TPCC and has been deemed suitable.

4.3.2 Panel Placement The entire surface area of each and every roll shall be inspected by the TPCC. The GCL surface inspection may occur during unrolling/installation to ensure that there is no damage to the material. The TPCC shall nominate if the damage is suitable for repair or if the panel shall be rejected based on the nature and location of the damage.

The GCL shall be deployed using a spreader bar or other approved equipment that shall limit deflection when roll is lifted. The Contractor shall ensure that the GCL is placed with the needle punched side facing upwards at all times. All installed GCL shall be covered and sealed by the overlying geomembrane before the end of each day. In no case shall any installed GCL or unwrapped rolls of GCL be left uncovered at the end of a day. Any GCL that has suffered premature hydration prior to being covered with geomembrane shall be removed to the satisfaction of the TPCC and the Principal.

All rolls of GCL shall be of sufficient length to ensure that it can be installed down slopes steeper than 1(v) in 4(h) in one continuous length from the top of the slope down to the toe. The GCL shall be secured in the shared anchor trenches at the crest of slopes as shown on the Drawings.




4.3.3 GCL Jointing The GCL rolls shall contain a standard 300 mm wide Bentonite enhanced overlap to ensure that a continuous seal is achieved between adjacent panels. The printed match line on the longitudinal edges of the GCL panels shall be used to ensure proper alignment; these works shall be to the satisfaction of the TPCC and the Principal.

The GCL edges shall be positioned to smooth out any creases and wrinkles in order to maximise contact with the underlying panel. Where wrinkles can not be removed by adjusting the position of the panel, the wrinkle shall be cut at its crest and repaired in accordance with the requirements of this Specification. Where self sealing joints are not present in the panel such as in areas across the width of the GCL or if the panel has been cut, the Contractor shall seal the GCL with a Bentonite paste in accordance with the manufacturer’s installation recommendations.

All GCL overlaps shall be a minimum of 300 mm. In all cases jointing shall be conducted in accordance with the manufacturer’s standard installation procedures.

4.3.4 GCL Repair Any damaged panels of GCL where the TPCC deems appropriate may be repaired by the Contractor. Damage that would be suitable for repair are expected to be in the form of minor cuts, tears or holes and shall be covered using a GCL patch. If a damaged area is a result of a manufacturing defect (e.g. the stitching between upper and lower geotextile has come apart) the roll or panel shall be removed and replaced. Additional peel tests may be required as a result of this fault occurring.

All patches shall be cut from a GCL roll and shall extend a minimum of 300 mm in all directions beyond the damaged area. Bentonite paste shall be placed around the perimeter of the defect to fully coat the overlap zone of the patch and be in accordance with the manufacturer’s installation recommendations.




5.0 GEOMEMBRANE LINER

A geomembrane liner shall be installed over the cells CCL (and GCL) surface, generally to the extents shown on the Drawings. The completed CCL earthworks have been completed to the satisfaction of the GTA and shall be approved by the Auditor prior to installation of the geomembrane liner.

5.1 Materials Specification 5.1.1 Geomembrane The geomembrane shall be High Density Polyethylene (HDPE) liner and meet the general requirements presented in Table 2 below. This Specification covers the requirements for smooth and smooth textured HDPE as specified by the Design Drawings.

The geomembrane material supplied shall be manufactured from a virgin premium grade HDPE and shall apply to both smooth and textured geomembrane as specified by the Design Drawings. The materials shall be free from surface folds, holes, blemishes, blisters, undispersed raw materials, or any sign of contamination by foreign matter. The Geomembrane shall adhere to the following specifications and be in accordance with the requirements of the Geosynthetic Research Institute (GRI) – GM13.

Table 2: Geomembrane Material Properties

Material Property Test Method Units Smooth HDPE Value

Smooth/Textured

HDPE Value

Testing Frequency

Minimum Thickness ASTM D5199 smooth

ASTM D5994 texturedmm

1.35 +Note 2

1.275 +Note 3

Each roll

Average Thickness ASTM D5199 smooth

ASTM D5994 textured

mm 1.5

1.425 +Note 4

Each roll

Density ASTM D1505 g/cm3 0.94 0.94 Each roll

Asperity Height GM 12 mm n/a n/a Each roll

Tensile Properties (Machine & Cross Direction)

- Strength at Yield ASTM D6693 (N/mm) 22 22 Each roll

- Strength at Break ASTM D6693 (N/mm) 40 16 Each roll

- Elongation at Yield ASTM D6693 % 12 12 Each roll

- Elongation at Break ASTM D6693 % 700 100 Each roll

Tear Resistance ASTM D1004 N 187 187 Each roll

Puncture Resistance ASTM D4833 N 480 400 Each roll

Carbon Black Content ASTM D1603 % 2-3 2-3 Per Batch

Carbon Black Dispersion ASTM D5596 +Note 1 +Note 1 Per Batch

Stress Crack Resistance ASTM D5397 hrs 300 300 Per Batch

Oxidative Induction Time (OIT) - Standard

ASTM D3895, 200�C; O2, 1 atm

Minutes >100 >100 Per Batch




The following notes relate to the geomembrane properties outlined in Table 1.

+Note 1: Dispersion only applies to near spherical agglomerates. 9 of 10 views shall be category 1 or 2.

No more than 1 view from Cat. 3.

+Note 2: The lowest individual of 10 values may be –10% of the nominal (mm) value.

+Note 3: The lowest individual value for any of the 10 values may be –15% of the nominal (mm) value.

+Note 4: The thickness may be -5% of the nominal (mm) value

5.2 CQA of Geomembrane 5.2.1 Manufacturer’s Report The manufacturer’s report shall be submitted with the geomembrane product delivered to Site which outlines the results for each property listed at the frequencies shown in Table 1.

No materials will be accepted for delivery to Site, or payment made, unless all necessary Manufacturer’s Quality Assurance certification data, as outlined in Table 2, has been provided to the Principal. All necessary data must be supplied in sufficient time, which includes time for review and approval of all information, such that no delay shall be caused to the project program.

Should the submitted material property data be deemed insufficient by the TPCC, Principal or Auditor to allow acceptance of the material, the Contractor must undertake independent testing of the material for the properties listed in Table 2 at a laboratory approved by the TPCC and Auditor. The cost of all materials testing required shall be borne by the Contractor and no cost variation or extension of time claims shall be made by the Contractor for variations in relation to such works.

5.2.2 Third Party CQA Representative The Contractor shall note that the Principal has appointed a Third Party Construction Quality Assurance (CQA) Consultant (TPCC) to provide full time on-Site supervision and monitoring of all geosynthetic lining works detailed by this Specification (including Section 4.0).

The TPCC will undertake (but is not limited to) the following typical works during the installation of the geosynthetic liner:

• Supervision of all HDPE geomembrane installation to inspect the entire surface area of each and every roll for tears, abrasions, indentations, cracks, thin spots, or other faults in the material.

• Supervision and authorisation of all test welds (tensile and peel) at the commencement of each shift and other times required by this Specification.

• Supervision of all non – destructive testing consisting of pressure testing and vacuum box testing, determination of non conforming welds and the implementation of rectification procedures required by this Specification.

• Authorising and supervising the destructive test sampling, on-Site testing and arranging the independent testing of the samples.

• Supervision of all cushion geotextile works including installation, jointing and damage repair ensuring the works conducted for each element meet the requirements of this Specification.

• Recording and logging of all liner installation activities consisting of panel placement, roll numbers, seam/weld locations, repairs and testing results for all works.




• Preparation of as built drawings which will act as a cross reference to the installation logs for all geomembrane and cushion geotextile.

• The final version of the as built records and drawings shall be completed electronically, with the records being tabulated and the drawings completed in AutoCAD format or other suitable drafting program.

Upon the completion of the construction works a Third Party CQA report shall be completed to certify that the works have been constructed in accordance with this Specification. The report shall contain the as built records and drawings for submission to the Principal and the Environmental Auditor to allow the commissioning of the works.

The cost of the TPCC works required by this Specification are covered by the Principal, however the Contractor shall bare the cost of all failed destructive tests and re-testing of destructive tests as required by the TPCC to provide compliance with this Specification. The Contractor shall note that the Principal may recover these costs by a reduction in the Contractors progress payments during the construction works.

5.2.3 Geomembrane Roll Information All geomembrane rolls shall be clearly labelled (typically using stickers secured on the inside edge of the deployment tube) with the following information:

• Roll Number;

• Batch Number;

• Material Thickness;

• Material Type (Smooth or Textured), and

• Manufacturer’s Name.

5.2.4 Handling & Storage The geomembrane rolls shall be protected from mud, dirt, chemicals, moisture, excessive heat, sharp objects or other damage before and during the installation process. Where necessary the covering of geomembrane rolls (using tarps or similar) may be required to protect the product from the above conditions. The geomembrane rolls shall be adequately stacked to allow ease of access for transportation during installation as well as roll identification.

5.3 Geomembrane Installation 5.3.1 Underlying Surface The HDPE geomembrane liner shall be placed above the finished surface (as approved by the Auditor) of all compacted clay. Upon completion of the clay liner works and prior to the commencement of geosynthetic lining the Contractor shall maintain the surface to be lined. The surface to be lined shall be free of any sharp objects, stones, debris, water and sudden changes in grade.

The finished surface is a nominated hold point and no geomembrane shall be installed until at least one inspection of the finished surface has been undertaken by the Auditor and has been deemed suitable.

5.3.2 Panel Placement The entire surface area of each and every roll shall be inspected by the TPCC, as appointed by the Principal prior to works commencing. The geomembrane surface inspection may occur during unrolling/installation to ensure that there are no tears, punctures, abrasions, indentations, cracks, thin spots or other faults in the material. It is responsibility of the Contractor to ensure that all damage within the liner during the works is identified and repaired in accordance with this Specification.




The Contractor shall employ installation methods that will prevent folds, wrinkles, bridging or tensioning. During installation the Contractor shall install sand bags over the panel’s free edges to prevent wind uplift, additional sand bags shall be placed where deemed necessary by the TPCC or Principal. The Contractor shall install sand bags attached to rope lines above panels placed on side walls.

The geomembrane sheets shall be installed so that the panels are continuous down side walls and not across the wall slope. All panels shall be overlapped onto adjacent sheets by a minimum of 125 mm and orientated so that the lap is in the down sloping direction (i.e. roof tile effect). All primary welds used to connect panel ends to sheets shall form T-joins (tee’s), which shall (at a minimum) be repaired via secondary welds in accordance with the requirements of this Specification.

The geomembrane material shall be secured within anchor trenches at the top of all crests in the general locations shown on the Design Drawings.

5.4 Geomembrane Welding Methods The geomembrane shall be welded together using the dual track fusion welding process as the primary weld. The extrusion welding process shall be used as the secondary weld and shall be generally restricted for repairs or where approved in areas that would be inaccessible to the dual track fusion weld.

5.4.1 Primary Weld Requirements The dual track fusion welding shall be conducted out using the split head wedge weld method which will fuse the upper and lower overlapped geomembrane sheets. The welding apparatus shall be fitted with a gauge(s) that at a minimum shows the weld temperature and speed. The welding process shall provide a central channel/void along the full weld length which shall enable pressure testing of the completed weld.

5.4.2 Secondary Weld Requirements The extrusion welding shall be conducted by extruding HDPE rod over the upper and lower section of the weld zone to achieve weld. The welding apparatus shall be fitted with a gauge(s) that at a minimum shows the weld temperature within the gun and at the shoe/nozzle. The extrudate rod shall be manufactured from the same material (i.e. HDPE) as the geomembrane sheet to be welded.

5.4.3 Geomembrane Weld Preparation Prior to commencing the welding process the Contractor shall ensure that the surface upon which the welding is to take place is cleaned to ensure it is free of water, mud, dirt, dust or other debris. The Contractor in the presence of the TPCC shall record the following information on the geomembrane adjacent to the weld.

This information shall also be recorded by the TPCC in a welding log records which will provide a cross reference to the as built drawings:

• seam number;

• date and time;

• welding technicians name/initials;

• welding apparatus number; and

• welding apparatus temperature.

Prior to secondary welding, the upper and lower sections may be tacked by a hot air welding device to prevent movement between the surfaces of the geomembrane during the welding operation. All secondary welding overlap surfaces shall be lightly abraded using approved mechanical equipment




(such as angle grinders). The abraded surface shall not be left for longer than one hour prior to the commencement of the welding process. The abrasion of the geomembrane shall be restricted to the immediate region of the weld and shall not extend outside the weld zone. Where over grinding is observed, the Contractor shall rectify this by removing the offending area as directed by the TPCC .

5.4.4 Weld Overlap All geomembrane panels subject to primary welding shall be overlapped by a minimum of 125 mm and be suitable to conduct all necessary construction quality assurance testing required under this Specification.

All geomembrane panels/patches subject to secondary welding shall be overlapped by a minimum of 75 mm and be suitable to conduct all necessary construction quality assurance testing required under this Specification.

5.5 Geomembrane Repair Defects or damage to the geomembrane may occur as a result of production, transportation or in the general course of installation works. It is the Contractor’s responsibility to identify and repair any defects, damage, punctures, tears, thin spots or other faults in the geomembrane. All such areas shall be clearly marked for repair, tested and recorded by the TPCC on the welding logs and cross referenced to the as built drawings.

It is the responsibility of the Contractor to ensure that all defects are repaired or replaced in accordance with the following requirements and to the satisfaction of the Principal and TPCC.

5.5.1 Patches Patches shall be cut from the same type of geomembrane (i.e. double smooth, smooth/textured or double textured) as used on the underlying panel area subject to the repair. Patches shall be typically circular in nature with at a minimum all corners rounded and shall be of large enough area to extend a minimum of 125 mm from the outer edge of any defect. The welding of all patches shall be in accordance with the secondary welding and testing requirements of this Specification. At no stage shall a patch be placed over an previously placed patch, should this situation occur, the patch shall be removed and replaced with a larger patch to cover the full extent of the damages areas.

5.5.2 Capping Capping may be used to replace a failed weld and shall be of the same type of geomembrane (i.e. smooth or textured) as used on the underlying area subject to the repair. Where a cap is being installed to repair a failed seam, the Contractor shall remove the full length of the failed zone to a minimum of 125 mm beyond the failed area. A primary weld shall be used to install the majority of the caps seams, with a secondary weld applied to close off the final section of the cap. The welding of all caps shall be in accordance with the welding and testing requirements of this Specification.

5.5.3 Repairs via Extrusion Weld Repairs to small defects in the geomembrane or to defective welds shorter than 1 m in length may be achieved via an extrusion weld. Repairs conducted using this method shall be carried out and tested in accordance with the extrusion (secondary) welding requirements of this Specification. Repairs to seams via extrusion welds greater than 1m shall only be conducted in areas approved by the TPCC. Should the length of the repair require extrusion welding greater than 1 m, in length, the weld may be subject to destructive and non destructive testing to confirm compliance with the requirements of this Specification at the discretion of the TPCC.




5.6 Weather Restrictions for Welding Field welding of the geomembrane shall not be conducted when the ambient is less than 5°C or greater than 35°C unless the Contractor can demonstrate that the requirements of this Specification can be achieved to the satisfaction of the TPCC and Principal. Geomembrane welding shall not be undertaken in the rain or through areas of water.

5.7 Construction Quality Assurance Testing on Field Welds 5.7.1 Trial Welds All welding technicians must successfully complete trial welds prior to commencing any welding shift, and at intervals of no greater than 5 hours thereafter, on a daily basis. Trial welds shall be performed by the technicians on all welding equipment that they will use during the shift. Welding apparatus and technicians that have not successfully completed a trail weld shall not be permitted to conduct any field welding function.

Trial welds shall be undertaken on samples of geomembrane sheet of the same type (or combination where smooth and textured material is being used) as what will be experienced in the field. The trial weld sample shall be a minimum of 300 mm wide by 1.5 m long, with the weld performed along the full central length of the sample. The trial welds shall be clearly labelled to indicate the time of the test, location and the field conditions that could influence the welds operation.

A minimum of two specimens shall be cut from the trial weld using a coupon cutter or approved equivalent, to produce a 25 mm wide specimen. One specimen from the trial weld shall be tested in peel and the other in shear to verify that the requirements outlined in Table 3 of this Specification have been achieved. All trial welds shall be tested onsite by the Contractor using a tensiometer fitted with a gauge to record the force (kg) exerted during the peel and shear testing of each specimen.

Table 3: Geomembrane Trial Weld Verification

Test Sheet Property Value (kg)

Minimum Value (kg)

Peel 56.5 40

Shear 56.5 45

As outlined in Table 3, the peel testing for both primary and secondary welds must meet a minimum of 70% of the sheet strength property value. For all peel testing of all primary weld specimens both tracks must be tested and meet the minimum vales outlined in Table 2. The sheer testing of both primary and secondary welds must meet a minimum of 80% of the sheet strength property value.

If either of the two specimens tested for any welding process fails the entire weld shall be deemed to have failed and the welding process shall be adjusted and repeated.

Upon testing of the specimens the failure mode shall be checked prior to approving the trail weld. All specimens shall fail in the geomembrane sheet and not in the weld area. The specimen shall be deemed to have failed within the weld if the weld has separated across more than 10% of the width of the weld.

5.7.2 Non Destructive Testing In order to check the ‘as constructed’ uniformity of the welds, all geomembrane seams, patches and repairs shall be 100% non-destructive tested along their full length. All primary welds shall be tested using the air pressure testing method and secondary welds tested using the vacuum box testing method as described by this Specification.




All onsite non destructive testing shall be undertaken in the presence of and to the satisfaction of the TPCC. Records of the testing results shall be noted on or next to the weld/patch and be recorded by the TPCC on the welding log records.

Air Pressure Testing

The air pressure testing of all primary (dual track fusion) welds shall be undertaken using an air pump fitted with a pressure gauge capable of reading a minimum pressure of 250 kilopascals (kPa).

Prior to pumping air into the weld, the ends of the weld shall be sealed to restrict air loss by grinding a hole at the far end of the weld and resealing via an extrusion weld. The pump shall then be used to obtain and hold a minimum pressure of 250 kPa within the weld for a minimum duration of 1 minute. Failure of the weld shall be recorded where a pressure loss of 15 kPa or greater is noted over the minute. At the successful completion of testing, the opposite end of the weld to the pressure gauge shall be cut to verify air release along the entire tested weld, and the pressure gauge shall be removed and sealed with an extrusion surface weld. Should the pressure in the gauge not drop upon the cutting of the seam, the blockage shall be located and the seam retested.

Where the weld was deemed to have failed, retesting of shorter lengths shall be undertaken to isolate the faulty zones. If the fault is of a short length, repair may be undertaken with a patch, cap or by a secondary weld. The TPCC shall determine whether a weld may be patched by fusion welding or covered by a patch over the affected area. A weld should not be patched more than one time. At the completion of repairs, the weld shall be re-tested to confirm compliance with the requirements of this Specification.

Vacuum Box Testing

The vacuum box testing of all secondary (extrusion) welds, including all patches and repaired sections, shall be undertaken using an approved vacuum box apparatus fitted with a gauge capable of reading a minimum negative pressure of at least -40 kPa unless approved otherwise by the TPCC.

Prior to sealing the vacuum box over the weld a soap/water solution shall be applied over the full seam length. Each section of the weld shall be tested to a minimum negative pressure of -40 kPa for a duration of at least 15 seconds, during which time the weld shall be examined through the viewing window for defects. If bubbles are evident in the weld, the weld is deemed to have failed. In the event of faults in the welds, repairs of the weld shall be undertaken and retesting with the vacuum box must be completed. Additional patches shall not be placed over an existing patch, and the Contractor shall ensure that testing of all secondary welds, patches, tee’s and caps has been undertaken.

5.7.3 Destructive Testing The Contractor shall recover field samples along primary welds which shall be subject to destructive testing in accordance with the requirements of this Specification. The exact location of each sample shall be at the discretion of the TPCC at the following minimum frequency:

• 1 sample per 200 m of primary seam welded.

Upon cutting of each destructive test sample from the field the Contractor shall ensure that the resultant hole is immediately repaired via patching in accordance with the requirements with this Specification.

All destructive testing shall involve cutting out a sample 300 mm wide by 1.5 m long over a completed field primary weld as the welding works progress over the cell. The sample shall be divided into three equal portions as outlined below.




3.7.3.1 Portion 1 – Independent Testing

Portion 1 shall be tested by an independent geomembrane testing authority in accordance with ASTM D4437, to the approval of the Principal. The independent geomembrane testing authority shall be appointed by the Contractor prior to commencing any lining works and the costs of all testing and reporting shall be borne by the Contractor.

A minimum of 6 specimens shall be cut from this portion with:

• 3 being tested in shear.

• 3 being tested in peel (both weld tracks).

All specimens shall meet the minimum testing values outlined in Table 3 of this Specification.

A copy of all independent test results shall be given to the Contractor and forward to the Principal within the Third Party CQA Report.

3.7.3.2 Portion 2 – On-Site Testing

Portion 2 shall be tested on Site by the lining Contractor as soon as the sample is taken and prior to submission of Portion 1 to the independent testing authority.

A minimum of 4 specimens shall be cut from this portion with:

• 2 being tested in shear.

• 2 being tested in peel.

All specimens shall meet the minimum testing values for tensile strength at yield, as outlined in Table 3 of this Specification. The on-Site destructive testing shall be carried out in the presence of the TPCC and the results of all tests shall be recorded and presented in the Third Party CQA Report.

3.7.33 Portion 3 – Archive Sample

Portion 3 shall be retained by the Principal for additional verification purposes if required until the works are fully completed. Where deemed appropriate by the TPCC, Portion 3 may be used within retesting for compliance.

5.7.4 Procedures for Failed Destructive Tests The ‘Portion 2’ destructive test sample shall be tested on Site for compliance prior to the submission of Portion 1 for independent testing. Should Portion 2 fail the on Site test, then Portion 1 shall not be submitted for independent testing and rectification procedures for the weld shall commence in accordance with this Specification.

Should either Portion reveal failure of the weld as outlined by this Specification then the extent of the failure zone within the constructed weld must be determined. The failure zone within the weld shall be determined by taking additional destructive test samples at 5 metre (maximum) offsets along the weld either side of the original test location.

This procedure shall continue until a passed sample is obtained either side of the original test location. Upon onsite passing of each sample, a portion of each sample shall be sent away for independent testing in accordance with the requirements of this Specification. The failure zone will be deemed as being isolated when it is bound by passing independently tested destructive tests. The identified failure




zone shall be repaired via patching, capping or secondary welding to the satisfaction of the TPCC in accordance with the requirements of this Specification.

Should the full weld length be deemed to have failed the weld shall be capped and any other welding works undertaken either side of that seam shall be destructively tested in accordance with Section 5.7.3 to verify compliance of the welding operations.




6.0 CUSHION GEOTEXTILE

A cushion geotextile shall be installed over the completed HDPE geomembrane to the extents shown on the Drawings. No cushion geotextile shall be installed until the TPCC has verified that testing of the HDPE liner has been undertaken and has passed the requirements of this Specification.

Two forms of cushion geotextile are required by this Specification for installation within Stage 2 and are referred to as base cushion geotextile and side wall cushion geotextile and shall meet the minimum requirements of Section 6.1. All cushion geotextile covered by this Specification shall consist of non-woven needle punched geotextile material.

6.1 Materials Specification The base cushion geotextile shall have the properties specified in Table 4 when tested in accordance with Australian Standard AS 3706.

Table 4: Base Cushion Geotextile Material Properties

Material Property Test Method

Units Minimum Value

Testing Frequency

Mass AS 3706 .1 g/m2 700 1 per batch

Grab Tensile Strength AS 3706.2 N 2 500 1 per batch

Trapezoidal Tear Strength AS 3706.3 N 1 000 1 per batch

CBR Burst Strength AS 3706.4 N 7 500 1 per batch

The base cushion geotextile shall have the properties specified in Table 5 when tested in accordance with Australian Standard AS 3706.

Table 5: Side Wall Cushion Geotextile Material Properties

Material Property Test Method

Units Minimum Value

Testing Frequency

Mass AS 3706 .1 g/m2 500 1 per batch

Grab Tensile Strength AS 3706.2 N 2 000 1 per batch

Trapezoidal Tear Strength AS 3706.3 N 800 1 per batch

CBR Burst Strength AS 3706.4 N 5 700 1 per batch

6.2 CQA of Cushion Geotextile 6.2.1 Manufacturer’s Report The manufacturer’s certificate of conformance (minimum level 2, or equivalent) shall be submitted with the cushion geotextile product delivered to site which outlines the results for each property listed at the frequencies shown in Table 4 and 5.

All necessary data must be supplied in sufficient time, which includes time for review and approval of all information, such that no delay shall be caused to the project program.




The application of a needle punched non-woven geotextile will require a certificate of conformance from the supplier / manufacturer, documenting the procedure adopted to minimise the inclusions of needles in the product supplied.

Should the submitted material property data be deemed insufficient by the TPCC, Principal or Auditor to allow acceptance of the material, the Contractor must undertake independent testing of the material for the properties listed in Table 4 and 5 at a laboratory approved by the TPCC and Auditor. The cost of all materials testing required shall be borne by the Contractor and no cost variation or extension of time claims shall be made by the Contractor for variations in relation to such works.

6.2.2 Handling & Storage All cushion geotextile delivered to Site shall be individually packaged with weather resistant wrapping; all packaging must be intact with no signs of damage. Any damaged rolls shall be inspected by the TPCC and the Principal to assess the extent of any damage and possible rejection of rolls.

The geotextile shall be protected from sunlight, moisture, sharp objects, mud, dirt, or any other damaging or deleterious conditions.

6.3 Cushion Geotextile Installation 6.3.1 Underlying Surface The cushion geotextile shall be placed above the finished HDPE geomembrane surface and to the general extents shown on the Design Drawings. The Contractor shall ensure that all CQA testing and recording has been fully completed on the geomembrane surface and all independent testing results received prior to cushion geotextile installation. The geomembrane surface to be covered shall be free of any sharp objects, stones, debris, or other potentially damaging objects to the satisfaction of the TPCC and the Principal.

6.3.2 Panel Placement The cushion geotextile surface shall be inspected during unrolling/installation to ensure that there is no damage to the material. The TPCC shall nominate if the damage is suitable for repair or if the panel shall be rejected based on the nature and location of the damage.

The cushion geotextile shall be deployed manually by rolling out by hand or using a spreader bar or other approved equipment, which shall limit deflection when roll is lifted. The Contractor shall employ installation methods that will prevent folds, wrinkles, bridging or tensioning. The Contractor shall take care not to entrap stones, excessive dust, or moisture in the geotextile during placement.

The cushion geotextile shall be secured in the shared anchor trenches at the crest of slopes and in the general locations indicated on the Design Drawings. All rolls of side wall cushion geotextile shall be of sufficient length to ensure that it can be installed down slopes in a continuous length from the crest and extending onto the toe at the base by a minimum of 1 m.

During installation the Contractor shall install sand bags over the panel’s free edges to prevent wind uplift, additional sand bags shall be placed where deemed necessary by the TPCC or Principal. The Contractor shall install sand bags attached to a rope lines above panels placed on side walls.

The cushion geotextile surface shall be inspected after installation to ensure that no potentially harmful foreign objects are present. The Contractor shall remove any such objects and shall repair or replace any damaged geotextile in accordance with the requirements of this Specification.

If white coloured geotextile is used, precautions shall be taken to prevent ‘snow blindness’ of personnel.




6.3.3 Cushion Geotextile Jointing All cushion geotextile panels shall be overlapped onto the adjacent panels by a minimum of 100 mm and the overlap shall be orientated using the roof tile method.

The cushion geotextile shall be jointed using thermal heat bonding undertaken with an approved hot air device. All thermal heat bonded joints shall be continuous along the full join length and to the satisfaction of the TPCC. The Contractor shall ensure that the bonding method in no way poses any risk of damage to the underlying HDPE geomembrane.

The cushion geotextile shall not have cross joints on slopes steeper than 1v in 5h; it is the Contractor’s responsibility to ensure the rolls ordered are of sufficient length to achieve this.

If the Contractor wishes to vary the method of geotextile joining outlined above, he is to notify the Principal and provide an alternative method statement in writing seven (7) days prior to commencement of works.

6.3.4 Cushion geotextile Repair Any damaged panels of cushion geotextile where the TPCC deems appropriate, shall be repaired by the Contractor at the Contractor’s expense. Damage that would be suitable for repair are expected to be in the form of minor cuts, tears or holes and shall be covered using a cushion geotextile patch.

All patches shall be cut from a cushion geotextile roll and shall extend a minimum of 200 mm in all directions beyond the damaged area. Upon cleaning of any debris from the overlap zone on the panel, the patch shall be heat bonded into place maintaining the specified overlap in all directions.




7.0 LEACHATE COLLECTION SYSTEM

The leachate collection system shall be generally installed to the locations and grades indicated on the Drawings. The leachate collection system typically comprises of a leachate collection pipe network, leachate drainage aggregate and a leachate collection sump as detailed on the Drawings.

7.1 Materials Specification 7.1.1 Leachate Collection Pipes The leachate collection (LC) pipes shall be 110 mmØ HDPE pipe and the header leachate collection (HLC) pipes shall be 160 mmØ HDPE pipe.

All LC and HLC pipes shall be PE100 or PE80 of type PN8 and where indicated on the Drawings shall be perforated by drilling holes in accordance with the applicable drill detail shown on the Drawings.

The leachate collection sump pipes consist of an extraction pipe comprising a minimum 3 m length of 600 mmØ HDPE PN8 pipe, which shall be perforated by drilling holes in accordance with the applicable drill detail shown on the Drawings. The extraction pipe shall lie horizontally over the centre of the sump base and shall be connected to a leachate riser pipe which shall extend up the side wall.

The leachate riser pipe shall be non perforated 600 mmØ HDPE PN8 pipe or 600 mmØ Black Max (or equivalent) SN8 pipe. Should a HDPE riser pipe be chosen by the Contractor for installation, the riser pipe shall be welded directly to the extraction pipe, using butt welding.

Should the Black Max riser pipe be chosen, the HDPE extraction pipe shall be fabricated to a HDPE sleeve that shall extend from the base up the side wall by a minimum of 1 m. The sleeve shall be of sufficient internal diameter to suit the insertion of the riser pipe (outside diameter and rubber ring joint) within the sleeve as shown on the Drawings. Prior to any welding, the angle of the base of the sump to the side wall shall be determined from the ‘as built’ survey data.

7.1.2 Leachate Drainage Aggregate The aggregate that shall be used within the leachate drainage blanket shall comply with the following properties:

• D85 greater than or equal to 40 mm;

• D10 greater than or equal to 20 mm;

• Fines content less than 1%;

• Free draining;

• Free of organic or other deleterious material such as limestone or other calcareous material that may be subject to chemical attack;

• Competent, and not deform or crush under loading, and

• Uniformity coefficient less than 2.

The leachate drainage blanket aggregate delivered to site shall be sampled and tested by the GTA for the parameters listed above, prior to the product approved for use. Further onsite inspections shall also be conducted by the Principal during product delivery to ensure that the material remains consistent.




7.2 Leachate Collection System Installation 7.2.1 Pipe Placement The LC pipelines shall be installed generally in accordance with alignments indicated on the Drawings and at maximum offsets of 25 m over the base of the cell within each valley line.

The HLC pipeline shall be installed generally in accordance with alignment indicated on the Drawings, along toe of the southern wall.

The LC pipes shall be connected to the HLC pipe along the southern wall toe for drainage into the leachate sump. In addition to the LC pipes, a 160 mmØ HDPE non perforated ‘clean out and inspection’ pipe shall be connected to the HLC at the sump and shall extend up to the top of the southern side wall.

The Contractor shall place and align the pipes across the floor in such a way that neither pipe nor base liner will be damaged. The Contractor shall take all necessary precautions during and after installation to ensure that dirt or other foreign material does not enter pipelines.

7.2.2 Leachate Collection Sump Construction A leachate collection sump shall be installed within the compacted clay liner at the low point of the cells valley line. The Contractor shall ensure that the minimum 1 m thick clay liner thickness is maintained in all areas of the sump and the sump is lined with the geosynthetic liner system as shown on the Drawings prior to commencing with the sump pipe and aggregate installation works.

Upon installation of the sump pipe works the leachate drainage aggregate shall be installed to fill the sump level with the top of sump. The incoming HLC pipe shall then be installed to continue through the sump and transition into the clean out line, prior to the installation of the remaining aggregate over the sump, as shown on the Drawings.

7.2.3 Pipe Welding All pipes shall be welded together as indicated by this Specification and the Drawings and to the satisfaction of the Superintendent. Prior to any joining of pipes, the Contractor shall ensure that all pipes are clean and dry and free of oil, grease or other deleterious material, and where necessary cleaned with an approved cleaning fluid.

The HDPE pipe lines shall be welding together to form continuous pipe lengths within the valley lines using fusion butt-welded or electrofusion couplings. In addition to those methods, the connection of LC pipes to the HLC pipe along the southern wall toe may be undertaken via extrusion welding or via butt –welding. Any fitting (i.e tee or cross) used to connect the pipes shall be of the same type and class as the pipes.

Field cutting, drilling or welding of pipes shall be made without damage to the pipe or any other component of the cells lining system. All defects shall be rectified to the satisfaction of the Superintendent.

7.2.4 Leachate Drainage Blanket Construction Prior to the installation of the leachate drainage blanket aggregate over the base the finished surface area shall be completed and approved to the satisfaction of the TPCC, the Superintendent and the Auditor. All leachate collection pipelines shall have been installed and jointed in accordance with the requirements of this Specification prior to distributing the drainage aggregate over the base.

Upon obtaining all necessary approvals, the approved aggregate shall be distributed across the cell from bridging layers over the cell floor. The bridging layer shall be at least 1 m thick and only approved construction equipment shall traffic over these areas.




A dozer and or excavator(s) may be used to spread and trim the drainage blanket from the bridging layer to a minimum depth of 300 mm over the cell floor. At no time shall trucks, construction equipment or vehicles other than the approved excavators and dozers traffic on areas other than the bridging layer. At no time shall any vehicles traffic on a layer less than 300 mm.

All aggregate shall be carefully distributed to prevent distortion or wrinkling of the underlying geosynthetic liner system. The Contractor shall ensure that the aggregate is carefully worked along the leachate collection pipe work maintaining their alignment and providing uniform support.

All due care shall be taken by the Contractor to ensure that the underlying layers of the CCL, geomembrane, geotextile cushion and leachate lines are not damaged or comprised during installation. Any damages incurred by the Contractor, shall be repaired at the cost of the Contractor.

The Contractor shall ensure that the blades or buckets of the dozer or excavators do not come within (approximately) 200 mm of the cell liner system at any time. Any damage caused to the liner system or pipes shall be rectified to the satisfaction of the Third Party CQA Representative.

7.2.5 Geotextile Fabric Filter Layer Upon installation of the drainage blanket to the required 300 mm thickness over the base of the cell, a layer of geotextile fabric (Bidim A12 or approved equivalent) having a mass not greater than 150 g/m2 shall be installed over the entire area of the finished drainage blanket surface.

The geotextile filter layer shall be installed having a minimum 300 mm overlap on side panels and 1 m overlap on end of roll panels, the overlap shall be glued, heat tack bonded and sandbagged. The Contractor shall provide a sufficient number of sandbags to remain in place over the finished geotextile fabric surface to prevent displacement of the material to the satisfaction of the Superintendent.

7.2.6 Side Wall Leachate Drainage Layer Upon installation of the geotextile filter layer (Section 7.2.5) and prior to the placement of any waste against the side wall liner of the cell a side wall leachate drainage layer shall be installed. The first 2.5 m (vertical height) layer of side wall drainage material from the base shall be conducted to the satisfaction of the Auditor and Superintendent and unless directed otherwise by the Superintendent, the remaining installation works shall be undertaken by the landfill operator during landfill works prior to filling of the next lift against the side walls.

The leachate drainage layer on the side walls shall consist of a 200 mm thick layer of free draining sand or other approved drainage material as per the material requirements outlined in Table 6. The proposed material shall be tested by the GTA at a frequency not greater than 1 test per 250 m3.

Table 6: Side Wall Leachate Drainage Layer Material Properties

Sieve Size Percent (%) Passing

13.5 100%

9.5 100 - 95%

4.75 100 - 95%

2.36 100 - 95%

0.425 95 - 75%

0.300 75 - 50%

0.075 50 - 5%




All subsequent layers shall be placed against the side walls in conjunction with the filling of waste in the cell and shall be maintained at a minimum height of 500 mm above the top of the current waste lift level. The drainage layer shall be extended up the wall in this fashion for the full height of all side wall liners within the cell.

7.3 Tolerances The following tolerances for the leachate drainage blanket shall be as follows:

• The minimum thickness shall be 300 mm with a tolerance of -0 mm.

7.4 Survey Upon completion of the pipe installation and on completion of the leachate drainage blanket each item shall be surveyed by a licensed surveyor who shall prepare as built drawings to show the as-constructed pipe alignment and leachate blanket levels thickness (perpendicular to the top of liner) over the base of the cell.


Technical Specification October 2008


Figure


October 2008 Technical Specification



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