Laserfiche WebLink
CLEARWATER <br /> G R O U P I N C <br /> Errvrrnnnrentaf Srr¢rcs <br /> Site Conditions <br /> This project was initiated following the removal of three underground tanks (USTs) and attendant <br /> dispensers and piping in 1992 Soil samples collected during the removal of these tanks indicated <br /> the presence of low to moderate concentrations of fuel hydrocarbon contamination Of the nine <br /> samples collected (three from beneath each former tank location) contamination was detected only <br /> in one sample collected from soils beneath the removed unleaded gasoline UST, quantified as 785 <br /> mg/kg TPH as gasoline in sample UGS. Benzene was also determined to be present in this <br /> sample, at a concentration of 0 445 mg/kg <br /> A detailed site assessment ensued, as required by California regulations The initial phase of site <br /> characterization included the installation of five monitoring wells, located strategically around the <br /> former UST basin and screened from their completed depth (40 feet bgs) to 25 feet below grade <br /> The results of this phase of the assessment were presented in a report prepared by McLaren Hart, <br /> (MH) dated February 3, 1993 <br /> . The former UST area was over-excavated in rune, 1993 Data presented by MH indicated that the <br /> original UST excavation was enlarged, and that 360 cubic yards of material was removed and <br /> transported to Forward Landfill for disposal <br /> Several additional phases of site characterization occurred following the preliminary assessment <br /> and over-excavation Activities completed included the installation of additional soil borings, and <br /> the collection of soil, water and soil vapor samples for laboratory analysis The results of these <br /> investigative activities showed the following <br /> • That a small area of residual contamination appeared to be present in the vicinity of the former <br /> unleaded UST (near the location of sample UGS, shown during initial tank removal to contain <br /> low levels of gasoline contamination) <br /> Sediments beneath the site have been shown as fairly fine-grained, consisting primarily of silt <br /> Such sediment types do not readily transmit water, and it is anticipated that groundwater <br /> beneath this site migrates only on the order of tens of feet per year, at best Contaminants in <br /> groundwater typically move much more slowly No evidence of a preferential pathway for <br /> groundwater movement has been provided, it is anticipated that water simply moves through <br /> the noted granular sediments under unconfined conditions <br />