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.� Mr. Stephen S. Chen Ooposal 8807-03 August 29 1988 Page 2 Monitoring Well MW-2 is located to be representative of ground-water quality in a northeasterly direction from the landfill . Monitoring Well MW-3 is located to be representative of ground-water quality in an easterly direction from the landfill . A review of the data collected from a soils investigation at the site (Soils InvestJation French Camp Sanitary Landfill Site, J.H. Kleinfelder & Associates; 1974) indicated that the depth to ground water in 1974 was approximately 30 feet. EMCON proposes that the monitoring wells be installed to final depths of approximately 20 feet below first-encountered ground water. Our drilling depth estimate considers that the ground-water level may have dropped since 1974 because of pumping in the Stockton area and that the ground surface at the site may have been built up by soil filling operations. To estimate a drilling depth EMCON has assumed a total of 210 feet (3 wells, 70 feet deep each) . A well drilling permit will be obtained from the San Joaquin Local Health District, before commencing any drilling. The drill holes will be advanced using hollow-stem auger drilling equipment. The wells will be constructed of 2-inch diameter polyvinyl chloride (PVC) casing and screen. The annular space between the drill hole and the well screen will be filter packed with a graded sand. A bentonite seal will be placed above the filter pack. The remaining annular space will be pressure grouted with a cement-bentonite mixture from the top of the bentonite seal to the ground surface using a tremie pipe. A locking steel well cover will be placed over the well casing and secured with concrete. An EMCON geologist will log soil samples from the drill hole according to the Unified Soil Classification System and standard geologic techniques. Soil samples for logging will be obtained from auger- return materials and by advancing a modified California split-spoon sampler equipped with stainless steel liners into the undisturbed soil beyond the tip of the auger. An exploratory boring log and a con- struction details data sheet will be prepared for each monitoring well . Two soil samples will be collected for vadose zone chemical character- ization. One soil sample will be collected from MW-1; the second sample will be collected from either MW-2 or MW-3. The soil samples for chemical analysis will be collected in stainless steel liners and sealed with Teflon tape and plastic caps. The liners will be placed in glass jars, packed on ice, and delivered to EMCON's laboratory with appropriate chain-of-custody documentation. EMCON proposes to analyze the soil samples for the following man-made compounds: • Volatile organic compounds by EPA Method 8240 • Semivolatile organic compounds by EPA Method 8270