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G 1 <br /> WORK PLAN FOR MONITORING <br /> WELL INSTALLATION <br /> at <br /> Former Unocal Service Station No 2859 <br /> 1665 Pacific Avenue <br /> Stockton,California <br /> ReportNo 240072 02-1 <br /> INTRODUCTION <br /> At the request of Unocal Corporation (Unocal), Gettler-Ryan Inc (GR) has prepared this Work Plan <br /> for additional subsurface assessment at the subject site The purpose of this investigation is to further <br /> delineate the downgradient extent of petroleum hydrocarbons in the soil and groundwater at this site <br /> This work was requested by the San Joaquin County Public Health Services Environmental Health <br /> Division (SJCPHS-EHD) in a letter dated May 4, 1999 In that letter, the SJCPHS-EHD stated that <br /> monitoring wells should be installed off-site and downgradient to determine the impact to soil and <br /> groundwater from possible migration of petroleum hydrocarbons in that direction Proposed well <br /> locations and groundwater flow direction are shown on Figure 2 Further,the SJCPHS-EHD suggests <br /> that the wells should be screened at a depth of 60 feet bgs, which they indicate is historically the most <br /> impacted depth on-site, and at 90 feet bgs to show that this deeper water-bearing horizon is not <br /> impacted These screen intervals match the depths of on-site wells MW-10 and NP-1 <br /> The proposed scope of work includes obtaining the required well installation permit from the <br /> SJCPHS-EHD and an encroachment permit from the City of Stockton Department of Public Works <br /> (SDPW), preparing a site safety plan, installing two groundwater monitoring wells, surveying the <br /> newly installed monitoring wells, developing and sampling the new wells, and preparing a report <br /> which presents the findings of the investigation <br /> The scope of work described in this Work Plan is intended to comply with the State of California <br /> Water Resources Control Board's Leaking Underground Fuel Tanks (LUFT) Manual, the California <br /> Regional Water Quality Control Board (CRWQCB) Tri-Regional Board Staff Recommendations for <br /> Preliminary Investigation and Evaluation of Underground Tank Sites,and SJCPHS-EHD guidelines <br /> SITE DESCRIPTION <br /> The subject site is situated on the southwest corner of Pacific Avenue and Walnut Avenue in <br /> Stockton, California Former facilities at the site consisted of a station building, one 550 gallon waste <br /> oil underground storage tank(UST),two dispenser islands,and two 10,000 gallon gasoline USTs that <br /> shared a common pit near the center of the site Location of pertinent site features are shown on <br /> • Figure 2 <br /> i <br />