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POUIN Z� THOMAS R. FLINN P.O. BOX 1810-1810 E. HAZELTON AVENUE " < STOCKTON,CALIFORNIA 95201 DIRECTOR rT (209)468-3000 FAX(209)468-2999 c4CiFO RN\P. www,sjgov.org/pubworks THOMAS M. GAU CHIEF DEPUTY DIRECTOR MANUEL SOLORIOor 1110 DEPUTY DIRECTOR f1 STEVEN WINKLER JUN 1 2009 DEPUTY DIRECTOR ROGER JANES June 12, 2009 E VIUCAEld i HEALTH F! BUSINESS ADMINISTRATOR PERMIT/SERVICES Mr. Todd Del Frate, PG California Regional Water Quality Control Board 11020 Sun Center Drive, #200 Rancho Cordova, California 95670 SUBJECT: WELL INSTALLATION WORK PLAN, HARNEY LANE SANITARY LANDFILL Dear Mr. Del Frate: Please consider this the Installation Work Plan required by Provision G.5 of Waste Discharge Requirement (WDR) Order R5-2009-00049. Two additional wells (MW-5 and MW-6) will be installed, each to address separate groundwater monitoring issues at the closed Harney Lane Landfill. Both wells will be installed to allow sampling approximately 10 feet below the water table (Figure 1) and in accordance with a well permit obtained from the San Joaquin County Environmental Health Department (EHD). MW-5 The purpose of MW-5 is to measure groundwater quality immediately up-gradient of well MW-4. This well will be installed between the wastewater treatment ponds of the temporary labor housing facility and the Secondary Site of the landfill (Figure 2). MW-6 The purpose of MW-6 is to establish up-gradient groundwater alkalinity, and should be installed where the water has not been affected by carbon dioxide from landfill gas. The County proposes the northwest corner of the temporary labor facility property. This location is approximately 600 feet cross-gradient from the up-gradient edge of the landfill, and therefore has a high probability of not being affected. To verify that the new well location will be beyond the affect of landfill gas, the County proposes to measure the subsurface gas composition at the proposed location and compare these measurements with those taken at three other locations that are assured to be beyond potential influence by landfill gas. These reference locations include two existing soil gas wells installed at other landfill properties distant from the refuse (Figures 3 and 4), and one push-probe sample taken at another County property southwest of the landfill (Figure 5 and Table 1). If the concentration of carbon dioxide at the proposed location is within the range of the reference locations, then the proposed location will be deemed adequate for the purpose, and a permanent well will be installed at the proposed location.