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Work Plan f"or Additional Site Assessment <br /> 1022 Frontage Road,Ripon,California <br /> C A M B R I A July 25, 2006 <br /> 158 cfm were observed during the SVE and SVE/AS constant vacuum tests, respectively. The <br /> maximum hydrocarbon mass removal rates of 22.73 pounds per day(lbs/day)and 39.771bs/day were <br /> observed during the SVE and SVE/AS constant vacuum tests,respectively. Approximately 11 pounds <br /> of hydrocarbons were removed during the two days of the feasibility testing. It was concluded that <br /> SVE/AS would be an effective remedial option for petroleum hydrocarbons detected in and above the <br /> shallow aquifer. <br /> 4.0 CONTAMINANT DISTRIBUTION <br /> 4.1 Petroleum Hydrocarbon Distribution in Soil <br /> Subsurface soils have been impacted by diesel,and to a lesser extent gasoline and MTBE as a result of <br /> a release(s)from the former fuel USTs, former fuel dispensers and related product piping, and the <br /> former waste-oil UST and related piping. The highest hydrocarbon concentrations are present near the"pig rr' <br /> former fuel USTs and the eastern former fuel dispenser. The lateral and vertical extent of impacted <br /> soil is adequately delineated in all directions except towards the southeast in the vicinity of waste-oil <br /> tank piping. The extent of diesel-impacted soil in the vicinity of MW-6 remains undefined. <br /> 4.2 Petroleum Hydrocarbon Distribution in Groundwater <br /> The lateral extent of dissolved-phase gasoline and diesel-range hydrocarbons is adequately defined in <br /> all directions except to the west and southeast of the site. MTBE concentrations up to 750µg/L have <br /> been detected west of the former USTs in downgradient well MW-10. Additionally, the extent of <br /> diesel-range hydrocarbons in the vicinity of well MW-6 is undefined. The vertical extent of the <br /> dissolved-phase gasoline and diesel-range hydrocarbons is undefined beneath the former USTs. <br /> 5.0 PROPOSED SCOPE OF WORK <br /> The objectives of the proposed scope of work are to: 1)assess whether the site is or has been affected <br /> by regional groundwater pumping from a municipal supply well located west of the site,2)assess the <br /> extent of impacted soil in the vicinity of the former waste-oil UST piping, 2) assess the extent of <br /> ,tills rounalWtJl�' <br /> y a <br /> .®L impacted soiin the vicinity of MW-6, 3) assess the vertical extent of dissolved-phase gasoline and <br /> diesel-range hydrocarbons beneath the former USTs, and 4) assess the lateral extent of dissolved- <br /> phase MTBE west of the former USTs. To meet these objectives,Cambria will conduct the following: <br /> • Obtain and review historical City supply well records; <br /> • Advance ten direct push Geoprobe° borings in the vicinity of the former waste-oil UST <br /> piping and MW-6, and collect soil and groundwater samples; and <br /> 6 <br /> i <br /> I <br />