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1• } AM1` Nva �., <br /> • <br /> lr: <br /> SE231 <br /> L <br /> rhe site has been impacted by petroleum product loss, uhlch has <br /> reached the underlying ground water. This conclu5lon 15 based on <br /> ;�- relatively high hydrocarbons concentrattcourirldetected <br /> water cbtatthe <br /> ed from <br /> shallcu bull ( 14-15.5 feet) sample <br /> and Hell 5-1 . The other 5011 borings had relatively low hydrocarbons <br /> concentrations in the soil. Therefore, the source for the <br /> product loss appears to be the tank complus. With only one site <br /> uell it 1s not possible to determine the local direction of <br /> slround-water flow or the extent of hydrocarbons in the Around <br /> water beneath the site. However,the relatively high hydrocarbon:: <br /> concentration detected 1n Well 5-1, which 15 located <br /> approximately 5 feet from the downgradient edge of the site <br /> (assuming regional flaw) suggests that hydrocarbons may have <br /> migrated off-site. <br /> Because the potential exists that hydrocarbons have (or will) <br /> spread off-sate, a thorough survey of nearby wells 5h 0uld be. <br /> conducted. This survey should focus on identifying all <br /> (documented or undocumented) well locations, detailing well <br /> sA ~� construction and determining well activity for well within a <br /> one-mile radius of the site. While it is known that municipal <br /> water is available in the area, it appear-, that nearby wells <br /> (private and municipal ) are used to supplement the supply (see <br /> Appendi,s C). Additional information may be available from the <br /> California Department of dater Resources and the City of <br /> Stockton. <br /> Results of the detailed well inventory may indicate the, need for <br /> additional observation wells between the site and any usable <br /> water supply wells. These wells would help to establish the <br /> extent of the hydrocarbon plume. <br /> The Regional Water Quality Control Board, Central Valley Region, <br /> is concerned about dissolved hydrocarbon concentrations thaf <br /> exceed the state action levels, therefore remediation may he <br /> required at the site. A brief discussion of state regulatory <br /> perspective is presented 1'l Appendix D. <br /> if you have any questiins regarding the contents of this report, <br /> please call. <br /> Respectfully submitted, <br /> pA I IC ENVIRONMENTAL GROUP, INC. <br /> in Garner <br /> Project Geologist <br /> _ S� W�� <br /> • <br /> 5u5an Willhite <br /> - — P11 ct Manager <br /> CEG 1272 <br /> 1dfl-12.41 F.qe 5 <br />