The City of Chilliwack (City) is seeking Expressions of Interest (EIs) from qualified Respondents to develop, design and construct the "Bailey Landfill- NE Wedge Liner Extension" (the "Project").
The purpose of this Request for Expressions of Interest (RFEI) is to solicit submissions from Respondents, with expertise in landfill liner engineering design and construction. The City may select up to three (3) Respondents who, at the RFP stage, will submit detailed technical and financial Proposals for the Project, depending on the quality and nature of the submissions received. The Work shall include, but not be limited to, the following:
NE Wedge Liner Extension Area
Landfilling in the NE Wedge Liner Extension area will take place over top of the existing east Site access road and fill in the wedge between the North East Expansion Area (NEEA) and the Original Landfill Area (OLA). The existing leachate collector pipes that drain the southern and eastern portions of the OLA will be re-routed through this lined area to discharge directly to MH15210 via non-perforated leachate pipes. Leachate from within the NE Wedge Liner Extension area will be collected in perforated lateral drainage pipes, or a drainage net to a collector pipe located along the northern edge of the liner extension that will discharge to MH15210. As part of the NE Wedge Liner Extension, surface water that is currently piped through this area will also be re-routed. Existing leachate infrastructure that is no longer in use will be decommissioned or abandoned. Base Liner
The base liner will be constructed in accordance with the Landfill Criteria, and will be comprised of a primary High Density Polyethylene (HDPE) geomembrane liner with a thickness of 1.5 mm and a Geosynthetic Clay Liner (GCL). The secondary GCL will have a hydraulic conductivity of 1 x 107 cm/s or less. The use of GCL was recommended in the DOCP due its relative ease of installation on steep slopes compared to a compacted clay liner. Based on the Landfill Criteria, and Site-specific conditions, the design criteria are as follows:
The base contours will be graded to provide a minimum of 2 percent slope for the primary drainage path and minimum 0.5 percent for the secondary drainage path.
The leachate collection system will be constructed of a continuous 0.3 m thick stone drainage blanket with perforated collector pipes with protective geotextile layers.
The stone drainage blanket will be constructed of 50 mm diameter clear stone.
A non-woven geotextile will be placed on top of the geomembrane liner prior to placement of the stone drainage blanket to protect the geomembrane liner against puncture.
An engineered filter layer shall be placed above the clear stone drainage blanket to maintain separation of the waste from the clear stone and to minimize the potential for ingress of fines into the stone drainage blanket.
Leachate collector pipes will be installed at a lateral spacing that provides a maximum spacing of 15 m and maximum drainage path of 50 m.
The collector pipes will be 200 mm-diameter in size and SDR11 in pipe wall thickness.
Clean outs are to be provided at the end of each of the leachate collector pipes.
The collector pipes will tie into the existing leachate collection system to allow leachate to be removed. A leachate head of less than 0.3 m at any point on the Landfill base liner.
Clean outs are to be provided at the end of each of the leachate collector pipes.
Approximate area of the NE Wedge is 9,200 square metres .
Refer also to GHD Drawing C-02 for Existing Leachate Management System, Drawing C19 for NE Wedge Liner Extension Leachate Collection System and C-25 for detailed crosssections (see Appendix E).
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