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S <br /> 1 • <br /> s� <br /> 3. Testing of a domestic well located on property adjacent to <br /> the Tri/Valley Growers did not record dissolved hydrocarbons <br /> above method detection limits. <br /> 4. Sampling of the soils excavated form the tank pit di.d not <br /> record hydrocarbons above detection limits thus lndicating these <br /> soils may be used to 1?111 In the excavation pits which remains <br /> open. <br /> The purpose of WaterWork's investigation is twofold; first, to <br /> sample the open tank pit excavation to deterrmine the degree of <br /> hydrocarbon contamination, if present, in order to assess the <br /> potential for backfilling, and secondly, define the extent of <br /> dissolved hydrocarbon contamination, down groundwater gradient <br /> from the tank pit and documented contamination in MW4 . To <br /> confirm the reported northeasterly groundwater gradient, <br /> WaterWork monitored and surveyed the four existing wells on May <br /> 26, 1988. The calculated flow is similar to the September 19, <br /> 1988 flow direction reported by Exeltech (Figures 3, 4) . A <br /> workplan to conduct the additional investigations is presented <br /> below. <br /> WORKPLAN <br /> A. Tank Pit Excavation <br /> I. Examine the soils in and around the former tank pit for <br /> evidence of hydrocarbon cantamination. <br /> 2. if no contamination is detected by field inspection, a <br /> total of six soil samples, one from each side and two from the <br /> pit bottom will be collected. These sir, samples will be <br /> collected by driving two inch diameter by six inch long brass <br /> tribes directly into the pit walls and bottom after removal of six <br /> Inches of soil. The brass sampler container will be sealed with <br /> foil, a plastic cap and tape. The labeled sample will be place <br /> In a refrigerated container and transported under chain of <br /> custody protocol to a state certified laboratory. <br /> 3. The six soil samples will be composited Into three and <br /> analyzed for benzene, toluene and xylene (BTX) and total <br /> purgeable hydrocarbons (TPH) as gasoline by State Department of <br /> Health services (DOHS) standard test methodology. <br /> 41f_-.._-.contamination.- --.is...detected.-- -by---....field .....--inspection, ......_._ _ _. <br /> preparations will be made for additional backhoe excavation. <br /> Soils would be excavated until field evidence indicates no <br /> hydrocarbons remain. At this point, soil sampling and analysis <br /> would be conducted as outlined In the above ijectlons 2 and 3. <br />