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Geafoaica(Technics inc. ~� Page 6 <br /> C& B Equipment <br /> Additional Site Characterization Work Plan <br /> Project No.336.2 <br /> July 15, 1996 <br /> Soil samples submitted to the laboratory will be analyzed for benzene, toluene, ethylbenzene <br /> and xylene (BTEX by EPA method 8020), and gasoline range petroleum hydrocarbons <br /> analyses (TPH-Gasoline by EPA method 5030/8015m). <br /> Groundwater samples including the domestic well will be tested for BTEX by EPA method <br /> 602, TPH-Gasoline using EPA method 5030/8015(m), and MTBE by EPA method 602 with <br /> positive detection confirmed by mass spectroscopy EPA 8260. <br /> v <br /> The detection limits for these compounds are listed below. <br /> DetectionLimits: aso me MIBE <br /> water µ <br /> Noll (pg/&g . <br /> 3.6 Groundwater Monitoring <br /> The new wells will be added to the existing quarterly groundwater monitoring schedule. The <br /> first monitoring event will be performed shortly after these new wells are installed. The local <br /> regulatory agency will be notified 48 hours prior to the sampling event. <br /> We recommend that the depth to groundwater be measured and gradient and flow direction <br /> be calculated on a monthly basis for a period of one year to evaluate the effects seasonal <br /> changes (i.e. precipitation and irrigation). The monthly groundwater level monitoring is <br /> proposed to begin immediately and the first event being performed in July 1996. After an <br /> annual cycle is on record, quarterly measurements may be appropriate thereafter. <br /> 4.0 GEOTECHNICAL & GEOCHEMICAL TESTING <br /> v <br /> Responding to the request by SJCPHSEHD for a better understanding of the site with respect <br /> to health risk and contaminant fate and transport we propose the following scope of work <br /> which is intended to provide critical site specific information for risk assessment modeling. <br /> 4.1 Lithologic Unit Testing Schedule <br /> Based on geologic information gathered during the earlier investigation we have summarized <br /> the geology of the site in the upper 20 feet below ground surface in a sketch cross section_ <br /> For planning purposes we have identified simply two distinct type of lithologic units present; <br /> sand with varying amounts of matrix and a silty clay. For this purpose we will assume that a <br /> good portion of the subsurface geology of the site will be represented by this testing. <br /> We propose to collect a sample representative of each of these units and test each for <br /> geotechnical parameters and chemical concentration. <br /> V <br /> V <br /> v <br />