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- -,+. �,�` f,�Y�y,?f�.,G� °"r�'h�"'''� �,.�,� � .tl °- s'v S•et" ;a�,�P 4+a' 7. r x �v ..,� <br /> E <br /> Y <br /> 4.0 FINDINGS OF THE INVESTIGATION <br /> F 4.1 LITHOLOGY <br /> i <br /> Characteristics of the aquifers and occurrence of <br /> r-� groundwater at the Stockton U-Haul site are typical for the <br /> San Joaquin Valley Ground Water Basin. The site is situated <br /> on alluvial and deltaic sediments :n the Centrad_ valley <br /> Geomorphic Province of California. <br /> .8 <br /> r; The unsat�_Aiated (vadose) zone beneath the site is <br /> composed of soils primarily consisting of various composites <br /> „v of silt, sand and some clay. Silt is tl-�e dominant vadose <br /> zone component beneath the Site. <br /> Most of the lithology of the vortion of the saturated <br /> a zone encountered during the investigation is composed of <br /> silt and clay. Groundwater was first encountered at 85 feet <br /> at MW-1, at 87 feet at MW-2, and at 86.5 feet at MLI-3. <br /> "i Gasoline odor was noted coming from the following depth <br /> intervals during drilling: <br /> a MW-1 - 30 feet through 85 .feet <br /> _NW-2 - 65 feet through 70 feet <br /> t tfii-3 - 20 feet through fly feet <br /> See Appendix E - well Boring Logs, and Appendix F - <br /> Geologic Cross Sections. <br /> R 4.2 ANALYTICAL RESULTS <br /> Fifty soil samples were obtained during the installatzi31___ <br /> location, analytical soil samples were collected at <br /> of the three monitoring wells. At each monitoring well <br /> r ' <br /> a approximately five-foot vertical intervals until shallow groundwater was encountered. As required ,oy the San Joaquin <br /> r county Environmental health Department, the samples were <br /> submitted to a California certified laboratory for Total <br /> petroleum Hydrocarbons (Gasoline) , and BTX&E analyses. The <br /> EPA analysis methods utilized by the laboratory were <br /> f 5030/LUFT and 8415M respectively. <br /> ` Laboratory analyses confirmed instances of contamination <br /> at each boring, with elevated levels found in soil from the <br /> MW-3 boring_ For a listing of contaminants tested for, and <br /> �.a their corresponding results, see Table 2, below. For <br /> laboratory result documentation and chains-of-custody, see <br /> Appendix B. <br /> M water samples from all three monitoring wells were <br /> collected on August 26, 1951. As required by the San Joaquin <br /> County Department of Environmental Health, the samples were <br /> 4 ETS ENVIRONMENTAL & ASSOC. <br /> PROJECT 305, PAGE 8 <br /> ri <br />