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1-ftw, Mr. Jim Barton RWQCB March 29, 2013 Page 4 Various VOCs (l,l-Dichloroethene, 1,1-Dichloroethane, sec-Butyl Benzene and cis-1,2- Dichloroethene) were detected at low levels (up to 7.0 µg/L) in groundwater samples from three borings. None of the VOCs detected exceeded California drinking water quality standards (Table 2 in Attachment B). Southeast Corner(Borings B-14 and B-15 Areas) In January 2001, the San Joaquin County Environmental Health Department (SJCEHD) provided site closure for three USTs in the southeast corner of the site: one 210,000- gallon #6 fuel oil UST,two 5,000-gallon #6 fuel oil USTs, and approximately 700 feet of connecting pipeline (AGI, 2005). Investigations conducted in this area in 2005 reported elevated concentrations of TPHd in soil and groundwater samples. A sample from Boring B-14 had a concentration of TPHd in soil at 43,000 milligram per kilogram (mg/kg). Boring B-15 reported TPHd in soil at 25,000 mg/kg. Boring B-11, located north of borings B-14 and B-15, reported TPHd in groundwater at 330,000 gg/L. In September 2012, URS advanced six borings (B-31 through B-35, and B-40) using direct push technology to further characterize petroleum impacts in the areas of borings B-14 and B-15. Three Shallow Borings (B-31, B-32, and B-40) To further characterize the lateral extent of TPHd in the vicinity of former boring B-14, one boring (B-32) was drilled near the former B-14 location to facilitate the collection of a groundwater grab sample and assess if groundwater has been impacted. Two additional borings (B-31 and B-40) were drilled to the southwest(down gradient) and east of boring B-14 to assess groundwater conditions in these areas. Groundwater samples were not collected in these areas during the previous investigations. Groundwater samples and one soil sample from each boring were analyzed for TPHg, TPHd, and VOCs. No constituents of concern were detected in soil or groundwater samples collected from borings B-31,B-32 and B-40 in the area of boring B-14. Three Shallow Borings (B-33 through B-35) To further characterize the lateral extent of TPHd in the vicinity of former boring B-15, one boring (B-34) was drilled adjacent to Boring B-15 to facilitate the collection of a groundwater grab sample and assess if groundwater has been impacted. Two additional borings (B-33 and B-35) were drilled to the southwest (down gradient) and south of Boring B-15 to assess groundwater conditions in these areas. Groundwater samples were not collected in these areas during the previous investigations. Groundwater samples and one soil sample from each boring were analyzed for TPHg, TPHd, and VOCs. Soil samples collected from borings B-33 and B-34 had concentrations of TPHg (up to 1.9 mg/kg) and/or TPHd (up to 370 mg/kg). Groundwater samples collected from borings B-33 and B-34 had concentrations of TPHd up to 850 µg/L. Um