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URS • Mr Harlin Knoll Senior Environmental Health Specialist San Joaquin County Environmental Health Department October 9, 2002 Page 2 SCOPE OF WORK To assess the vertical and lateral extent of petroleum impacted groundwater, URS proposes the installation of one deep on-site monitoring well and two shallow off-site monitoring wells at the locations indicated on Figure 2 Field activities will be conducted as described in the Supplemental Investigation Work Plan, with the exceptions discussed below Prior to initiating field activities, URS will obtain permission from Union Safe Deposit Bank to install two wells on the bank property and to collect quarterly groundwater samples from these wells The two off-site soil borings will be drilled in the parking lot of the Union Safe Deposit Bank to depths of approximately 60 feet bgs or 20 feet into groundwater One on-site soil boring will be drilled on the site property, between the station building and the underground storage tank (UST) complex This boring will be drilled to approximately 100 feet bgs The boring will be continuously cored to allow for accurate lithologic Iogging . The three soil borings will be converted to groundwater monitoring wells as described in the Supplemental Investigation Work Plan The shallow wells will be screened from approximately 30 to 60 feet bgs and the deep well will be screened over a five-foot interval in a deep permeable zone to be assessed in the field The actual well construction details will be based upon soil and groundwater conditions encountered in the field Groundwater Monitoring Well Development,Sampling,and Surveying After installation, the groundwater monitoring wells will be developed by rigorously surging over the length of the screen interval and by purging a minimum of ten casing volumes of water The wells will be surveyed to mean sea level by a licensed surveyor Groundwater samples will be collected from the newly installed groundwater monitoring wells a minimum of 48 hours after well development Groundwater samples will be analyzed for TPH-g and BTEX by EPA Method 8015/8021 and fuel oxygenates by EPA Method 8260B Attachment H presents detailed groundwater sampling and analysis procedures Report Preparation Fallowing receipt of the analytical results, a report will be prepared summarizing the results of the investigation Included in the report will be the well drilling and construction procedures, monitoring well construction specifications, and tabulated groundwater data K V5 BP ARCOU 1191/11191 WP Addendum doc