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Ms Lon Duncan <br /> . May 24, 2002 <br /> Page 4 of 5 <br /> access drilling ngs typically have depth limitations that may hinder such an investigation in the <br /> area of the UST After the lateral extent of contamination has been determined we can more <br /> adequately evaluate the feasibility of conducting an investigation of the vertical extent of the VOC <br /> plume in the source area or perhaps somewhat downgradient of the source We do not propose <br /> the drilling of any deep borings or monitoring wells at this time <br /> Feasibility Testing <br /> The relatively high viscosity of the free product (waste oil) measured in well MW3 renders the <br /> free product plume relatively immobile This is supported by analytical results of groundwater <br /> samples collected from site perimeter wells (MWI, MW2, MW4), which have been free of <br /> petroleum hydrocarbon constituents since groundwater sampling was initiated in December 2000 <br /> (Table 2) The measured thickness of free product in well MW3 has been steadily declining since <br /> Ground Zero initiated a program of regular product bailing from the well, from a historical high of <br /> 1 47 feet on September 21, 2001 to 0 10 feet on March 18, 2002 A chart showing the decline in <br /> measured product thickness over time is included as Figure 3 <br /> Approximately 21 8 gallons of product/water mixture has been removed from the well since <br /> bailing was initiated in September 2001 However, the volume of product that can be removed <br /> • from the well is limited by the rate of recovery of the product And as stated previously, the high <br /> viscosity of the product relative to water limits the rate of recovery into the well In order to <br /> evaluate the feasibility of increasing the rate recovery of free product into well MW3, Ground <br /> Zero proposes to conduct a limited pump test in well MW3 <br /> The data collected to date from well MW3 indicates that the measured product thickness has <br /> generally been greatest as the depth to water increases This apparent relationship is illustrated on <br /> Figure 4 Ground Zero will attempt to maintain a sufficient pumping rate from well MW3 in <br /> order to maintain the measured depth to water in the well at between approximately 24 and 25 <br /> feet bgs The most recent depth to water available for May 13, 2002 was 23 13 feet bgs The <br /> necessary drawdown in the well therefore is expected to be approximately 1-2 feet Based upon <br /> well development logs from well MW3, we expect to maintain a pumping rate of approximately <br /> 1 5 gallons per minute in order to exert a drawdown of 1-2 feet during the test Ground Zero will <br /> pump water from the well at this rate for an expected duration of 8-10 hours Ground Zero will <br /> measure depth to product and depth to water at regular intervals for the complete duration of the <br /> test Water pumped from the well will be contained in temporary storage containers (portable <br /> poly tank or DOT-approved 55-gallon drums) pending disposal <br /> Reporting <br /> Following the receipt of analytical results, a technical report describing the methods and results of this <br /> investigation will be submitted to San Joaquin County Department of Environmental Health The <br /> is feasibility <br /> will describe to the degree possible the nature and extent of contamination, the results of <br /> feasibility testing, and will contain recommendations for additional work as appropriate <br /> G1DaWGROUNDZEIGABBARDIwoikplam\3_add_MW WORKPLAN doc <br />