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dhM <br /> URS Greiner Woodward Clyde <br /> Ms. Carol Oz, R.E.H.S. Page <br /> LOP/Site Mitigation Unit ` <br /> San Joaquin County—Public Health Services <br /> Environmental Health Division <br /> September 14, 2000 <br /> were drilled with 8.25-inch outside diameter(OD) augers to accommodate the installation of a 2-inch diameter <br /> +� groundwater monitoring well. The total depth of each boring was approximately 15 feet bgs. A copy of the soil <br /> boring logs is included as Attachment H. <br /> To assess the lateral and vertical extent of the petroleum impacted soils, soil samples were collected using a <br /> California-modified split spoon sampler at 5-foot intervals beginning at 1 foot bgs and continued until groundwater <br /> was encountered; at approximately 5 to 7 feet below ground surface. Static groundwater was found at <br /> approximately 4 feet bgs. A portion of each sample was retained for field screening analysis. Based on the results <br /> of field screening, one soil sample from each of the borings was submitted to Curtis&Tompkins,Limited (Curtis <br /> &Tompkins), a California State Certified Laboratory,for analysis of TPH-G by EPA method 8015 modified-, and <br /> �. BTEX, MTBE, tert-butyl alcohol (TBA), di-isopropyl ether(DIPE), ethyl tett-butyl ether (ETB), and tert-amyl <br /> methyl ether(TAME)by EPA method 8260. The samples were sealed in plastic bags and stored in an ice-filled <br /> chest at approximately 4°C until delivery to the laboratory. Each soil sample was delivered to the laboratory within <br /> the appropriate holding times and was accompanied by the chain of custody(COC)documents. <br /> The monitoring wells were constructed using 2-inch diameter(ID), schedule 40,flush-threaded polyvinyl chloride <br /> (PVC) well casing. Well installation included 10 feet of screened well casing, approximately five feet of blank <br /> PVC well casing, and a flush-mounted well vault. A Monterey No. 3 silica sand filter pack was installed from the <br /> bottom of the boring to six-inches above the well screen. A 1-foot bentonite seal was placed above the sand pack <br /> and neat cement was used to seal the remaining annular space to the surface. Each well was also fitted with a <br /> '— locking cap and lock. <br /> Soil cuttings generated during the drilling activities were placed in labeled 55-gallon Department of Transportation <br /> �.• (DOT)-approved steel drums pending disposal. <br /> The equipment used in the drilling of the wells was thoroughly cleaned using a high temperature, high-pressure <br /> ,.. steam cleaner before commencing work and between each borehole. The wastewater generated during the <br /> equipment cleaning was stored in labeled 55-gallon DOT-approved steel drums pending disposal. <br /> Following well installation the groundwater monitoring wells were surveyed to a common datum by a professional <br /> land surveyor. Horizontal locations and vertical elevation for each well were recorded to an accuracy of 0.01 feet. <br /> Groundwater Monitoring Well Development <br /> A minimum of 72 hours following monitoring well installation,the wells were developed by purging approximately <br /> 10 well casing volumes of water from each well. During well development, temperature,pH, specific conductivity <br /> and turbidity were monitored to evaluate development results. A copy of the well development data sheets is <br /> `�.. included as Attachment III. <br /> v <br /> 11URS_SACIIWPROCESS114214102_TRACY%TRACY REPORT-2.DOC <br />