SITE INFORMATION AND CORRESPONDENCE

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AUG 20 '97 02:54PM a-EARWATER GROUP P.2r7 %00001 C—L—E—A-4RINATER . w i:urrir6+r•r�lrf$rr�irrr site,C This project was initiated following the removal of three underground tanks(USTs) and attendant dispensers and piping in 1992. Soil samples collected during the removal of these.tanks indicated the presence of lorry to moderate concentrations of fuel hydrocarbon contamination. Of the nine samples collected(three from beae-alb each former tank location)contamination was detected only is one sample collected from soils beneath the removed unleaded gasoline UST,quantified as 785 mg/kg TPH as gasoline in sample UGS. Benzene was also determined to be present in this sample,at a concentration of 0.445 mZfg. A detailed site assessment ensued,as required by California regulations. The initial phase of site characterization included the installation of five monitoring wells,located strategically around the- former UST basin and screened from their completed depth,(40 feet bgs) to 25 feet below grade. The results of this phase of the assessment were presented in a report prepared by McLaren Haat, (MH) dated.February 3, 1993. The former UST area was over-excavated in Tune, 1993_ Data presented by MH indicated that the original UST excavation was enlarged, and that 360 cubic yards of material was removed and transported to Forward L.audfill for disposal. Several additional phases of site characterization occurred fallowing the preliminary assessment and over-excavation. Activities completed included the installation of additional soil borings,and the collection of soil, water and soil vapor samples for laboratory analysis. The results of these investigative activities showed the following; • That a small area of residual contamination appeared to be present in the vicinity of the former unleaded UST(near the location of sample UGS, shown during initial tank removal to contain low levels of gasoline contamination). • Sediments beneath the site have been shown as fairly fine-granted,consisting primarily of silt. Such sediment types do not readily transmit water, and it is anticipated that groundwater beneath this site migrates only on the older of tens of feet per year, at best. Contaminants in groundwater typically moue much more slowly. No evidence of A preferential pathway for groundwater movement has been provided; it is anticipated that water simply moves through the noted granular sediments under unconfined conditions.