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EDMUND G. BROWN JR. <br /> 4! GOVERNOR <br /> my'o <br /> CALIFORNIA AMM MATTHEW RODRIQUEZ <br /> WaterBoards SECRETARY FOR <br /> ENVIRONMENTAL PROTECTION <br /> Central Valley Regional Water Quality Control Board <br /> Rt:UJ:1VED <br /> 25 January 2016 J <br /> 1 <br /> N1R01V1qE,VTAL N <br /> Taj M. Bahadori, P.E. PF jrSER���ALTti <br /> San Joaquin County Department of Public Works S <br /> P.O. Box 1810 <br /> Stockton, California 95201 <br /> APPROVAL OF FINAL CONSTRUCTION QUALITY ASSURANCE(CQA) REPORT, <br /> MODULE 2- PHASE A; WASTE DISCHARGE REQUIREMENTS ORDER R5-2015-0058; <br /> FOOTHILL LANDFILL, SAN JOAQUIN COUNTY <br /> Central Valley Water Board staff reviewed the December 2015 Final CQA Report (As-Built CQA <br /> Report, Construction of Area 2A at the Foothill Sanitary Landfill) prepared by Advanced Earth <br /> Sciences, Inc. documenting construction of Module 2, Phase A at the Foothill Landfill. The design <br /> report for the 15-acre module was approved on 28 January 2015 (copy of letter enclosed) and an <br /> interim CQA report for the module was approved on 14 October 2015. The latter approval and a <br /> subsequent extension authorized the Discharger to operate the module until 31 January 2016 <br /> pending submission and approval of the Final CQA Report. This letter supplants previous interim <br /> approvals to operate the module. <br /> The Final CQA Report provides the results of field and laboratory CQA testing conducted during <br /> installation of the module's monitoring and containment system components, including subgrade; <br /> pan lysimeters; soil gas collection piping; foundation layer; geosynthetic clay liner (GCL) and <br /> HDPE geomembrane layers; geotextile layers; leachate collection and recovery system (LCRS) <br /> layer and sump; operations layer; trenches and other project elements. CQA testing for earthwork <br /> construction generally included field compaction testing, soil thickness surveys, and laboratory <br /> permeability; while CQA testing of geosynthetic layers generally included conformance, seam, and <br /> shear testing. Single interface and multi-layer (sandwich) shear testing was conducted to verify <br /> parameters used in slope stability analysis and identify the critical interface of the liner system <br /> (HDPE geomembrane-GCL). Appropriate testing was also conducted on the LCRS and LCRS <br /> sump gravel layers (e.g., particle size, hydraulic conductivity). <br /> CQA activities also included electrical leak detection testing of the module's geomembrane liner. <br /> Direct contact (i.e., water puddle) leak detection testing was conducted in all areas (i.e., floor, <br /> excavation side slope, and LCRS sump), while leak detection testing after installation of operations <br /> and LCRS layers (i.e., Dipole Method) was limited to the floor of the module. No leaks were <br /> detected in the geomembrane layers by either method. <br /> The report includes a detailed description of the above CQA activities along with project <br /> information such as construction specifications; as-built drawings; laboratory test sheets; daily field <br /> reports; photographs; geosynthetics layer panel layouts; earthwork and piping survey data and <br /> maps; CQA procedures, geosynthetic materials inventory; manufacturer's CQA data, contractor <br /> memoranda; and other CQA documentation. <br /> KARL E. LONGLEY SCD, P.E., CHAIR I PAMELA C. CREEDON P.E., 9CEE, ExecU vE OFFICER <br /> 11020 Sun Center Drive#200,Rancho Cordova,CA 95670 1 www.waterboarda.Ca.oOv/centralvalley <br /> C?RecYceo wAvea <br />