Laserfiche WebLink
05 November 2007 <br />AGE-NC Project No. 06-1481 <br />Page 2 of 5 <br />valley (Olmsted and Davis, 1961); the site itself is located on unconsolidated and semi-consolidated <br />alluvium, lake, playa and terrace deposits of Quaternary age (California Division of Mines and <br />Geology, 1977). Rocks composing the basement complex of the Province have not been completely <br />defined but are believed to be metamorphic and igneous in origin. <br />The Modesto, Riverbank and Turlock Lake Formations and overlying Recent alluvium are the <br />principal sources of domestic ground water in the 13,500-square mile San Joaquin Valley Ground <br />Water Basin (Basin 5-22). Based on a Fourth Quarter 2006 monitoring event at a property less than <br />an eighth of a mile to the south-southwest from the site, Top Filling, 101 Wilson Way, Stockton, <br />California, depths to ground water ranged from 37.98 and 40.60 feet below the top of the casing <br />(btoc). The shallow and deep ground water was inferred to flow generally toward the northeast. <br />However, this may be greatly modified by local recharge and discharge patterns. <br />2.2. UNDERGROUND STORAGE TANK REMOVAL <br />A 22,000-gallon fuel oil tank (Fuel Oil #6) located approximately 35 feet from the northeast corner <br />of the western-most building on Parcel 153-040-03 was filled in-place in 1986. A 1,000-gallon UST <br />was removed from the southeast corner of the western building on Parcel 03 in 1986; soil <br />contamination was found to be immediately below the tank and soil was over-excavated in the area <br />of the tank. Confirmation sampling noted non-detect for all analytes and the site was closed by San <br />Joaquin County Environmental Health in 1996. <br />2.3. PREVIOUS SITE ASSESSMENTS <br />On 24 July and 25 July 2007, AGE advanced six soil borings (B-2 through B-7) in the areas of <br />potential environmental concern identified during historical research to assess for possible <br />contaminant-impacted soil and ground water beneath the site. Soil borings were advanced utilizing <br />a van-mounted Geoprobe 5400 direct-push probing unit equipped with 1.25-inch probing rods; the <br />Geoprobe advances soil probe borings using a hydraulic hammer to drive soil sampling tools to <br />specified depths. Two borings (B-5 and B-7) were advanced to a depth of 10 feet below surface <br />grade (bsg), and two borings (B-3 and B-4) were advanced to a depth of 20 feet bsg; only soil <br />samples were collected from these borings. Soil borings B-2 and B-6 were advanced to total depths <br />of 47 feet and 45 feet bsg, respectively; both soil and ground water samples were collected from <br />these borings. The location of soil borings are illustrated on Figure 2. <br />Nine soil samples (B2-10, B2-30, B3-15, B4-10, B4-15, B5-10, B5-20, B6-35, and B7-10) and two <br />grab ground water samples (B2-W and B6-W) were submitted to Cal Tech Environmental <br />Laboratories (CTEL), a California Department of Health Services-certified laboratory, for analysis <br />Advanced GeoEnvironmental, Inc.