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The site lies within the Sacramento Valley which is comprised of unconsolidated Quaternary <br /> sediments from alluvial and lake deposits. The sierra Nevada Mountains located to the east are <br /> the source of the alluvium deposits as a result of erosion. Also contributing to the deposits are <br /> the Sacramento Valley Coast Ranges to the west. Both ranges consist of a wide variety of <br /> material consisting of plutonic, metamorphic and sedimentary rocks. First encountered <br /> groundwater in the vicinity of the site is not known however based on review of nearby site data, <br /> first encountered groundwater is expected to be greater than 30 feet below grade. Faulting in <br /> present in the area with the Stockton Fault trending northeast/southwest is located within the city <br /> limits, and the Midland Fault Zone (north trending) is located approximately 25 miles north of <br /> the site. <br /> Field Activities <br /> On Wednesday December 10, 2014 V&W Drilling of Stockton, CA was onsite to advance the <br /> five (5)proposed Geoprobe® soil borings (B-1 through B-5). A California Registered Geologist <br /> from HES was also onsite to screen soil samples, to log the soil conditions encountered and to <br /> collect soil and groundwater samples (if necessary). The approximate locations of the soil <br /> borings advanced are shown on Plate 2. <br /> Soil boring B-1 was advanced in the parking lot on the north side of the J.F. Donaldson Tire <br /> Shop building at 242 East Miner Avenue. The boring was advanced to an approximate depth of <br /> 20 feet below grade (BG) using truck mounted Geoprobe drilling equipment. The boring was <br /> advanced through a 6-inch diameter concrete core hole that extended approximately 6-inches <br /> BG. The boring was located within a few feet of a former feature identified on a historical <br /> Sanborn Fire Insurance Map as "Gas Well TK". Soil samples were collected continuously for <br /> evaluation from approximately 4 feet BG to approximately 20 feet BG. Soil samples were <br /> collected from the boreholes using a 2-inch diameter, 4-foot long acrylic sample tube. The <br /> sample tube was placed inside a drilling rod and driven into the soil at the desired sampling <br /> depths. Upon sample collection the samples selected for chemical analysis were cut from the <br /> acrylic tube and lined with non-adhesive Teflon tape and plastic caps and then labeled and <br /> placed under refrigerated conditions pending laboratory chemical analysis. <br /> In general the soils encountered in B-1 consisted of silty fill material with brick fragments from <br /> approximately 1 foot below grade to approximately 2-3 feet below grade. The fill material was <br /> underlain to approximately 20-feet BG by brown silt with some clay and sand. Variations in <br /> color, sand and clay content were observed however the soil was fairly consistent throughout the <br /> borehole. No petroleum or solvent odors or soil dis-colonization was noted during drilling and <br /> photo-ionization (PID) readings were at background levels. Soil conditions were moist near the <br /> bottom of the borehole however no groundwater was encountered in the borehole. <br /> 2 <br />