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Ms. Amy Terrell May 15, 2008 Page 2of4 v An application to install three onsite groundwater monitoring wells was previously prepared and submitted with appropriate fees to the San Joaquin County Environmental Health Division (SJCEHD), and was approved December 10, 2007. Permit applications necessary for the remaining four wells will be submitted to the SJCEHD following approval of this scope of work. A site visit will be performed to mark the location of the proposed wells. Following the site visit, Underground Services Alert (USA) will be notified of drilling at the marked locations. It is anticipated that USA and their affiliated companies will mark the offsite locations of underground utilities in the vicinity of the proposed monitoring well. Results of utility locating by USA will be reviewed and the final locations of monitoring wells will be selected. Soil and Groundwater Investigation SGI plans to install five shallow wells and two deep wells in the vicinity of the Site. Two shallow wells are planned for installation on the western parcel of the Site. One additional onsite well will be installed on the eastern parcel at the Site. The remaining wells will be located offsite. The attached figures show the proposed locations of the monitoring wells. The following is a description of the methods that will be employed to install the groundwater monitoring wells. Soil borings in advance of the shallow wells will be drilled to a total depth of 40 feet below ground surface (bgs). The wells will be continuously logged and sampled at approximate 5-foot intervals using either hollow-stem auger or sonic drilling methods. The two deep wells will be drilled to approximately 200 feet bgs. Drilling and sampling will be conducted using sonic drilling techniques for the two deeper well. Hand augering of the first 5 feet will be performed as an extra safety measure to protect against damage to underground utilities. Soil samples will be collected continuously. Soil samples from the boreholes will be visually evaluated. Visual description of soil samples will include the following information with depth: • percentage of sample recovery; • depth to first encountered groundwater; • grain size classification (USCS; percentages of gravel, sand, silt, and clay); • color (Munsell color chart); • density; • odor; and, • degree of moisture. Selected soil samples from the boring will be analyzed for nitrate using EPA Method 300. Shallow wells will be constructed using two-inch diameter schedule 40 polyvinyl chloride (PVC). It is anticipated that the well screen for these wells will extend from 20 to 40 feet bgs. The well screen will be two-inch diameter schedule 40 PVC with 0.020 inch slots. The sand pack will be #2/12 Monterey or equivalent. Bentonite pellets will be placed above the sand pack and hydrated, followed by placing a neat cement grout to the surface. The Source Group,Inc.