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Site Background Information -Ripon Farm Service Page 9 of 10 OFF-SITE ASSESSMENT - MONITORING WELL INSTALLATION Two off-site ground water monitoring wells(MW-9 and MW-10)were installed on 15 April 2005. Soil pilot borings MW9 and MW 10 were completed as ground water monitoring wells using two-inch diameter PVC casing with 0.020-inch slotted screen installed from approximately 15 feet to 35 feet bsg in both borings with blank casing extended to the surface. The filter pack (No. 3 Lonestar sand)was installed from approximately 15 feet to 35 feet bsg. The lead scavenger 1,2-DCA was the detected in the samples from well MW-4, the off-site wells MW-9 and MW-10. ADDITIONAL CVRWQCB GROUND WATER ASSESSMENT The Central Valley Regional Water Quality Control Board (CVRWQCB) directed by letter dated 16 July 2004 that RFS should characterize the quality of ground water,as well as ground water flow direction and gradient, at the RFS facility to determine if activities at the RFS facility have contributed to possible high nitrate concentrations in local ground water. On 10 and 11 October 2005,four soil pilot borings for monitoring wells MW-101 through MW-104 were advanced using a CME-75HT drill rig,equipped with 8.25-inch diameter hollow-stem augers. The pilot borings were completed as ground water monitoring wells using two-inch diameter PVC casing with 0.020-inch slotted screen installed from approximately 20 feet to 40 feet bsg with blank casing extended to the surface. CONFIRMATION SOIL AND GROUND WATER SAMPLING On 16 August 2007,AGE sampled four off-site,soil borings that were advanced in conjunction with the UST investigation at the Ripon Farm Service (RFS) site. The field work was conducted in accordance with procedures approved by the EHD presented inAdditional Off-Site Assessment Work Plan,dated 04 August 2006. The sampling assembly was advanced using"direct push"technology. A total of four shallow soil probe borings(B20 through B23)were advanced to 30 feet below surface grade(bsg),utilizing a truck-mounted Geoprobe 5400 equipped with 1.25-inch diameter probe rods with an attached 2-inch diameter water sampler. The borings were installed at the western edge of State Highway 99. The borings were advanced to 30 feet bsg; ground water was encountered at approximately 30 feet bsg and the water table level increased to near 25 feet bsg.Grab ground water samples were collected from soil borings utilizing a Geoprobe water sampling assembly. Ground water recharge was low in boring B22,likely due to the low permeability sediments above the water table in the boring trace. Advanced GeoEnvironmental,Inc.