SITE INFORMATION AND CORRESPONDENCE

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Chaney,Walton &McCall (LLQ The preparation and assessment of these PHS/EHD Worksheets are discussed below, as one of the issues that PHS/EHD is requested to reconsider. Issues Identified for Reconsideration by PHS/EHD The most important aspect of this UST closure is that the soil sample collected from the base of the excavation (from beneath the former tank) did not contain TPHg or gasoline constituents above the County's maximum allowable concentrations. Similarly, there was no indication that discolored soil or other unusual conditionV was found at the time kC+ of the UST removal. Furthermore, neither VFO tank inventory monitoring,nor tank integrity testing ever indicated that a potential UST system release had occurred. The two important issues that may have been incorrectly identified or overlooked during the early August 1999 review by PHS/EHD staff are described below: 1. The November 1991 Site Closure Evaluation prepared by PHS/EHD includes a "Leaching Potential Analysis" as well as a comparison of laboratory analysis results with the maximum allowable criteria for petroleum hydrocarbons. The Leaching Potential Analysis is a scoring system used to determine the magnitude of the PHS/EHD maximum allowable concentrations of petroleum hydrocarbon constituents in soil, including benzene, toluene, ethylbenzene, xylene (BTEX) and total petroleum hydrocarbons as gasoline (TPHg). This evaluation considers that depth to water beneath the Site is approximately over 80 to 90 feet below grade._ h& k Wo,,�j kvvt Jc- The comparison of petroleum hydrocarbon constituents is summarized as follows: Collected 11/12/91 Benzene Toluene Eth (benzene Xylenes TPHg Maximum allowable 1 0.30 0.30 1.00 1.00 100.0 Concentration(mg/Kg ) in Soil Samples Reported Concentration 0.004 0.06 0.02 t• 0.20 2.6 (mg/kg)in Soil Sample Collected from Base of the Tank Excavation Reported Concentration 0.02 0.27 0.25 2.88 19.8 (mg/Kg))in Soil Sample Collected from the Excavated Soil Pile Milligrams per kilogram(mg/Kg)or parts per million by weight. The Closure Evaluation Worksheets document that only a grab sample of stockpiled soil had one gasoline constituent exceeding its maximum allowable concentration. That constituent was xylene, which is considered biodegradable and non-carcinogenic (USEPA, Integrated Risk Information System [IRIS]- downloaded 0911999). Consequently, it is not reasonable to presume that a petroleum hydrocarbon release had occurred at this Site based on the relatively small exceedance of a biodegradable, non- carcinogenic constituent in a grab sample of stockpiled soil. ^kA{,,,, ,L t, 4;:, v,_(, P-�-f DFIOOIOI.SJCPH.1et.101599 3 530.758.8128 v/f rccgroup@earthl ink.net