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Project No. 013-10141 <br /> Page No.2 <br /> of 25 feet above mean sea level within the northeastern quarter of Section 44,Township 1 North,Range 7 <br /> East,Mount Diablo Baseline and Meridian. <br /> 3.0 REGIONAL GEOLOGY AND HYDROGEOLOGY <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. The groundwater in the area is reported to be fust <br /> encountered at a depth of approximately 50 to 55 feet bgs. The groundwater flow direction in the area of <br /> the subject site is generally towards the east. <br /> 4.0 BACKGROUND <br /> As presented in Krazan's April 6, 2010 Phase I Environmental Site Assessment report of the subject site, <br /> Krazan identified no evidence of recognized environmental conditions (RECs) in connection with the <br /> subject site as defined by ASTM E 1527-05. However, the following potential environmental concerns <br /> (PECs)were identified in connection with the subject site: <br /> • During Krazan's April 2, 2010 site reconnaissance an operational wash rack was observed in the <br /> northern portion of the on-site building and access ports for an associated subsurface clarifier <br /> were observed adjacent to the east of the building. Surface staining associated with a 240-gallon <br /> double-walled waste oil aboveground storage tank(AST)located adjacent to the west of the wash <br /> rack was observed adjacent to the AST; although no surface staining was observed immediately <br /> adjacent to the wash rack drains. The visible portions of the wash rack drain and an associated <br /> trench drain were observed to have good structural integrity; however, standing water and <br /> sediment/sludge within the drains precluded observation of much of the interior of the drains. <br /> Additionally, two floor drains and access ports for a subsurface clarifier associated with a former <br /> wash rack were observed in the southern portion of the on-site building during Krazan's site <br /> reconnaissance. The two floor drains were dry and no odors, surface staining, or other evidence <br /> of the disposal of hazardous materials or hazardous waste was observed within or adjacent to the <br /> drains. According to Mr. Joe Doran, Manager of United Rentals, the subject site occupant, <br /> familiar with the subject site for 37 years, the wash rack located in the southern portion of the <br /> building was utilized prior to the development of the operational wash rack in the mid-1980s. <br /> Mr. Doran stated that both wash rack clarifiers are connected to the municipal sewer system and, <br /> to the best of his knowledge, have never required significant repair. Mr. Doran stated that the <br /> KRAZAN&ASSOCIATES,INC. <br /> Conducting Assessments Nationwide <br /> 1310141 Uvited Rentals LSI DRAFT.doe <br />