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1 . <br />' MONITORING WELL CONSTRUCTION <br /> . AND GROUNDWATER SAMPLING AND ANALYSIS <br />' BECKMAN ROAD SITE, LODI, CALIFORNIA <br />' 1.0 INTRODUCTION <br /> This work plan has been prepared in response to a letter dated February 10, 1992 from the San <br /> Joaquin County Public Health Services Environmental Health Division (EHD) to the San Joaquin <br /> County Mosquito Abatement District (SJCMAD) which requested submission of a work plan for <br /> monitoring well construction, groundwater sampling and analysis at the SJCMAD site located <br /> at 200 North Beckman Road, Lodi, California (Figure 1) <br /> 1.1 Background <br /> In 1986, three underground storage tanks were removed from the site and an investigation was <br /> conducted to determine the extent of hydrocarbon constituents in soils in the vicinity of the <br /> former tank locations The investigation was performed in four phases, one of which included <br /> excavation down to a depth of 31 feet below grade Analytical results of the soil samples <br />' collected during the four investigation phases indicated that Total Fuel Hydrocarbons (I`FHC) <br /> and benzene, toluene, ethylbenzene and xylene (BTEX) were present at a depth of 31 feet <br /> 1 i beneath the gasoline tank location Samples collected beneath the weed oil and F-oil tanks <br /> revealed no detectable hydrocarbon compounds below two feet beneath the bottom of the tanks <br /> 1 in December 1986, three groundwater monitoring wells (MW-1, MW-2 and MW-3) were <br /> installed on the site in order to determine the groundwater flow direction (groundwater gradient) <br /> beneath the site and to test the groundwater for possible hydrocarbon presence Based on water <br /> elevations in the three wells, the groundwater gradient beneath the site was toward the northeast <br /> (as of March 18, 1987) Sample analyses showed no detectable hydrocarbons in any of the <br />' wells <br /> In 1991, the EHD requested that SJCMAD begin a quarterly groundwater monitoring program <br /> 1 for the three wells This program was initiated in December 1991 by ROY F WESTON, INC <br /> (WESTON) However, during the first monitoring event WESTON discovered that two of the <br /> three monitoring wells onsite were dry (MW-2 and MW-3) Sampling of only MW-1 was <br /> 1 completed and the resulting analysis (no detectable hydrocarbons) was submitted to the EHD <br /> Due to the fact that only one well contained water, the EHD requested installation and sampling <br /> of an additional well to be situated in the downgradient location. <br /> The following sections of this work plan present the methods which will be used to construct the <br /> 1 downgradient monitoring well and sample and analyze the groundwater <br /> 1 <br /> i <br /> 1 1 <br />