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3 <br /> Tom Mason Page 2 <br /> David Heinrich <br /> Another significant level change in TPHg concentration occurs: as <br /> soil data. shows from Area 2 northerly to. Area 1. TPHg soil. <br /> concentrations in EB-8 were documented at 50,00 ppm at 25' bgs <br /> The closest northerly soil sample is from GB-10 at; :5' bgs:, where <br /> 980 ppm. Of :TPHg was detected. Combined with hist orIcal data that <br /> approximates the building, UGTs and fueling island locations, and. <br /> sitewe: can usage:, wcan only conclude that them are substantial on- <br /> site soutces to warrant remeelial activity. <br /> With al-1 of the submittals for MTBE and the concentrated. <br /> discuss l.ons over the potential of an offs-site source for the. <br /> groundwater corrztamift4tlon, the impression is that the on-g.. to <br /> sources of contamination :have not received theIr fair :share of <br /> concern. <br /> PHS-EHD is impressed with the soil contamination reduction from <br /> the vapor extraction in .Area 3 and the potential for fort er $oil <br /> contaminatioin reduction as asby the results from the <br /> vapor gest ;from V[+�t 5`. Also impressive is the level of recent <br /> assertive investigative actions by the FDIC as the sole <br /> responsible party to attempt to delineate more of the soil and <br /> groundwater problems.. <br /> It is the requirement of PHS-EHD that Texaco actively enter the <br /> investigative and remediation arena and begin on-site activities <br /> immediately. Since previous soil vapor extraction .from VW-1 has <br /> shown favorable results, this alternative; for remediation as well <br /> as any ether method should be evaluated and a. feasibility study <br /> that addresses remedial methods (at Least two as required by UGT <br /> Regulations, Title 23, Article 11-) should be prepared and <br /> submitted to PHS-EHD for review and approval along with an <br /> estimate of casts. <br /> if remedial costs and feasibility for the remediation methods of <br /> the petroleum impacted soil cannot support its use, PHS-EHD will <br /> then evaluate sail modeling that support conclusions that the <br /> mass of petroleum impacted sail will not reach and de-grade. the <br /> groundwater beneath the site. <br /> PHS-EHD. Wil.l not discuss closure./site certification until .the: <br /> existing soil plumes on site are ;addressed in. deta 1. ©nce: on- <br /> site soil c©ndit. .ons. are adequately addressed:, PHS-SSD will <br /> evaluate groundwater aff site: source concerns . Without an <br /> attempt to remediate the ;known on-site soil: contamination or <br /> luo.:I: icatron to support "no further action" ;requests, PHS-EHD <br /> cannot evaluate or approve closure requests. <br />