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Ms. Margaret Lagoria • • December 5, 2007 Page 2 of 4 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 location of monitoring well will be selected. Soil and Groundwater Investigation The Source Group plans to install five shallow wells and two deep wells at or near the Ripon Farm Service 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, possibly in the caltrans right-of-way. Access has already been secured for the western parcel. The following is a description of the methods that will be employed to install the groundwater monitoring well. Locations of the two wells on the western parcel and the eastern onsite parcel are shown on the enclosed figure. A map with the locations of the proposed offsite wells will be submitted once access has been secured. Soil borings in advanced 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 hollow-stem auger drilling methods. The two deeper wells will be drilled to approximately 200 feet bgs, with conductor casing installed to approximaltey 150 feet bgs. Drilling and sampling will be conducted using mud rotary auger drilling techniques for the two deeper wells. 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 borehole 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 this well will extend from 20 to 40 feet bgs. The well screen will be constructed using 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. For the two deeper wells, once the depth of 150 feet bgs is reached, the borehole will be reamed to a diameter of 14 inches using mud rotary drilling techniques. A 10-inch diameter The Source Group,Inc.