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' <br /> Fc <br /> F <br /> .+ted <br /> CHAPTER 4 <br /> ii <br /> FIELD AND ANALYTICAL RESULTS <br /> ; + <br /> TO evaluate <br /> Station 939, soil and groundwater quality beneath ARCO Service <br /> four selected subsurface soil samples from each borehole <br /> �o (12 total) and one groundwater sample from each monitoring well (3 <br /> its total! were analyzed for fuel characterization, <br /> xylene (BTX) , and total lead at Brown and Caldwell ��;enzene, toluene, <br /> Cal- <br /> laboratory. (DC) Emeryville <br /> Soil =1ua�lith <br /> FIA' During drilling, vapors <br /> d <br /> each borehole werscreened emitting <br /> a frrQoto onization ndeeS taken from <br /> fi <br /> readings obtained are r p detector. The <br /> were open to the air; however,tatheeresultsmeasurewere used ment uto selecse the t <br /> e samples for laboratory analysis. Results for samples analyzed are <br /> summarized in Table 4-1. Constituents in each soil sample analyzed 3. <br /> are below California Department of Health Services (DHS) designated <br /> action levels. <br /> I. <br /> Groundwater Qualit <br /> 3� <br /> On April 2, 1987, after pumping to discharge for approximately <br /> 1 to 10 minutes, a water sample from Municipal Well 12 was collected by <br /> Brown and Caldwell personnel and sent to BC's laboratory for <br /> ki + analysis. Results are summarized in Table9-2. Labor <br /> evefor <br /> ator <br /> are included in Appendix B. All constituents analyzed in thersamrle <br /> were below DHS designated action levels the <br /> groundwater <br /> quality, protection poE <br /> s On April 10, 1987, groundwater samples from monitoring wells W-1, <br /> yf W-2, and ;'-3 were collected by Brown and Caldwell personnel and sent <br /> to BC's laboratory for analyses. Results are summarized in <br /> 'Table 4-2. <br /> t The benzene concentration identified in each sample <br /> exceeded the DHS action level. Toluene and xylene levels exceeded <br /> their DHS action levels in samples from wells W-2 ard W-3. None of <br /> -- the total lead levels identified exceeded <br /> pr water <br /> standards for lead. NO levels have been stabl.ishedk�for for <br /> hydrocarbons. The highest total concentration of Fuel hydrocarbons <br /> and BTX were identified in <br /> sample W-3. <br /> s lateral t p Well W-3 is Located at a <br /> gradient from she leak site. <br /> _ - .r---_mowed_lateral-ly--in -trench kiackfill before migrating downwards to the <br /> water table. It is also possible that some unkown factor may have <br /> 3 influenced the product migration. According. to the station manager a <br /> gasoline station has existed at this site since the s <br />