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0 <br /> WORK PLAN FOR THE REPAIR OF THE CLAY BARRIER LAYER <br /> At the Harney Lane Sanitary Landfill <br /> INTRODUCTION <br /> The closure cap was damaged due to erosion along the southern edge of the landfill top deck <br /> (Fig. 1). The inlet of the downcomer was observed floating in stormwater and rendered <br /> ineffective. The inlet has since been anchored so that this will not occur in the future. <br /> Investigation of the cut indicates that an area of the clay barrier layer approximately 20 feet long <br /> and 2 feet wide has been damaged. The erosion into the clay barrier was over a foot deep but did <br /> not extend beyond the clay layer; no refuse was exposed(Fig. 2). To prevent additional damage, <br /> the affected area, has been covered with plastic (Photo 1). <br /> PROPOSED CORRECTIVE ACTION <br /> Two repair options are proposed. Both involve placing a geocomposite clay liner (GCL) over and <br /> beyond the affected area. We will use the same GCL that was approved for the base liner at North <br /> County Landfill Module 1. Specifications of this material include: <br /> GCL Model: Bentofix Thermal Lock NWL <br /> Bentonite content: 0.84 lb/ft2 at 12% moisture <br /> Grab Strength: 150 lb minimum average roll value <br /> Permeability: 5x10-9 cm/sec maximum <br /> Peel strength: 45 lb minimum <br /> If multiple pieces of GCL are used, the pieces will be overlapped a minimum of 12 inches and <br /> granular bentonite will be sprinkled in the overlap to prevent moisture intrusion. The affected area <br /> will be covered with vegetative soil, compacted, and the reseeded. <br /> Repair Option 1 <br /> This option involves removing the vegetative layer directly over the cut in the barrier layer. The <br /> remaining barrier will be exposed and smoothed prior to placing the GCL(Fig. 3). This option <br /> will require the use of a backhoe only. <br /> Repair Option 2 <br /> This option involves removing a larger amount of the vegetative layer and the barrier layer to the <br /> depth of the bottom of the cut. This area will then be smoothed prior to placing the GCL(Fig. 3). <br /> This option will require the use of a bulldozer only. <br /> N:\1 Harney Lane\S_Edge_PropErosionRepairA.doc <br /> Proposed Repair of Closure Cap 1 San Joaquin County Public Works/Solid Waste <br /> Harney Lane Sanitary Landfill May 1,2006 <br />