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Project No. 034-17016 <br /> Page No. 3 <br /> proximate to hazardous waste and/or hazardous materials handling and storage areas. Additionally, <br /> Krazan's review of drawings of the truck maintenance shop facility dated 1991 and presumably <br /> associated with its original construction indicates that portions of the existing shop were originally <br /> designated as wash bays and that a steam cleaner was located adjacent to one of the wash bay areas for an <br /> unknown period of time (the steam cleaner is no longer present and the previously designated wash bay <br /> areas are now utilized for truck repair/service operations). Within the truck maintenance shop building <br /> minor surface staining was observed immediately proximate to the trench drains at the time of the site <br /> reconnaissance, and moderate surface staining was observed proximate to a grated drain/sump located <br /> within a lube pit in the northeastern portion of the maintenance shop. An oily liquid was observed in the <br /> base of the lube pit sump and the sump appeared to contain a pump. According to a maintenance foreman <br /> employed by the owner of the subject site, the truck shop trench drains located on ground level are <br /> connected to adjacent subsurface clarifiers within the maintenance shop building, and he indicated that <br /> those clarifiers and all plumbing fixtures located within the maintenance shop building are in turn <br /> connected to a subsurface oil/water separator located adjacent to the south of the truck maintenance shop <br /> building. The maintenance foreman stated that the drain/sump located in the base of the lube pit is <br /> connected to the oil/water separator directly or is connected indirectly via connection to a nearby clarifier. <br /> The oil/water separator reportedly discharges to the City of Lathrop municipal sewer system. <br /> Truck/Trailer Wash Bay Oil/Water Separators/Clariflers/Trench Drains <br /> Trench drains, floor drains, and/or subsurface sumps/clarifiers/separators were observed in association <br /> with an on-site truck wash bay and the on-site warehouse building. The truck/trailer wash bay, located <br /> adjacent to the east of the truck maintenance shop, appears to have been constructed in approximately <br /> 2006. Trench drains were observed within the truck/trailer wash bay and a drain potentially associated <br /> with a subsurface clarifier was observed in the central portion of the wash bay. The maintenance foreman <br /> stated that the trench drains and the drain/clarifier located within the truck wash bay are connected to an <br /> oil/water separator located adjacent to the east of the wash bay building. The maintenance foreman <br /> indicated that the oil/water separator discharges to the City of Lathrop municipal sewer system. <br /> Geologic and Hydrologic Setting <br /> The subject site is located within the San Joaquin Valley, a broad structural trough bound by the Sierra <br /> Nevada and Coast Ranges of California. The San Joaquin Valley, which comprises the southern portion <br /> of the Great Valley of California, has been filled with several thousand feet of sedimentary deposits. <br /> Sediments in the eastern valley, derived from the erosion of the Sierra Nevada, have been deposited by <br /> major to minor west-flowing drainages and their tributaries. Near-surface sediments are dominated by <br /> sands and silty sands with lesser silts, minor clays, and gravel. The sedimentary deposits in the region <br /> form large coalescing alluvial fans with gentle slopes. Data obtained from an environmental investigation <br /> KRAZAN&ASSOCIATES,INC. <br /> With Offices Serving the Western United States <br /> 034-17016 WP for LSA SSI Laltuvp FINALAw <br />