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C <br />January 6, 2006 <br />Job No. 2005-082 <br />Forward, Inc. <br />9999 S. Austin Road <br />Manteca, California 95336 <br />Attention: Mr. Lochlin Caffey <br />REVIEW OF AS -BUILT CONSTRUCTION QUALITY ASSURANCE TRESTING <br />NORTH & NORTHWEST SLOPES FINAL CLOSURE <br />FORWARD SANITARY LANDFILL — SAN JOAQUIN COUNTY, CALIFORNIA <br />Geo -Logic Associates (GLA) is pleased to provide Forward, Inc. with the following <br />comments regarding the Construction Quality Assurance (CQA) test results submitted by <br />Vector Engineering, Inc. (Vector) during recent construction of the final cover over the <br />north and northwest slopes of the Forward Sanitary Landfill in Manteca, California <br />(Table 1). These slopes were designed to a California Code of Regulation (CCR) Title 27 <br />(27 CCR) prescriptive standard for an unlined Class III landfill and since the closure area <br />is unlined in this area, this constitutes a simple prescriptive final cover. <br />In June of 2005, GLA completed modeling of a desiccated prescriptive final cover <br />constructed using on-site borrow soils to estimate the performance of this final cover <br />system over time. The results of that modeling indicated that with fully developed <br />intermediate root depth vegetation, the full final cover system (i.e., the foundation, <br />vegetative and barrier layers together) should accommodate desiccation of the barrier <br />layer without loss of prescriptive performance and could, in fact, allow for its <br />incorporation into closure of future lined and unlined areas of the landfill. In order to <br />validate that modeling, Forward has proposed to monitor the performance of the final <br />cover that has been constructed over a period of two years. <br />DESIGN AND AS -BUILT MATERIAL CHARACTERISTICS <br />As a part of the initial modeling, and based on the original borrow evaluation, GLA <br />developed a Construction Quality Control Plan for construction of the final cover. This <br />plan identified the maximum in-situ saturated hydraulic conductivity, the minimum as - <br />built compaction and moisture content requirements and the recommended grain -size <br />distributions for construction. In general, these requirements were: <br />Saturated Hydraulic Conductivity <br />Compaction <br />Moisture Content <br />Percent Passing the #200 Sieve <br />cA2005-0082 1/0611W_ <br />< 1.0 x 10-6 cm/s <br />>= 90% of Maximum (ASTM D-1557) <br />+- 2% of Optimum (ASTM D-1557) <br />70% <br />