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J� Unocal Service Station No 0187 September 21, 1994 FIELD ACTIVITIES Field work was performed in accordance with the GSi Site Safety Pian 7827.03, dated July 1 , 1994 Underground Service Alert (USA) was notified prior to beginning drilling activities The drilling was performed under SJCEHD permit number 93-1883 Three onsite groundwater monitoring wells (U-1 through U-3) were installed and five onsite exploratory soil borings (U-I through U-M) were drilled July 6 through 8, 1994 The well and exploratory borings were drilled using a truck-mounted hollow-stem auger rig by West Hazmat Drilling of Rancho Cordova, California (license #C57-554979) A GSi geologist observed the drilling of the borings, described the encountered soil, and prepared a log of each boring Logs of the soil borings are presented in Appendix B Well borings U-1 , U-2, and U-3 were drilled to 55, 60, and 55 feet bgs, respectively Exploratory soil borings U-1 through U-M were drilled to depths of 16 5, 41 5, 46 5, 50 5, and 46 5 feet bgs, respectively. Groundwater monitoring wells were constructed in well borings U-1 through U-3, as discussed below Exploratory borings U-1 through U-M were backfilled to ground surface with neat cement containing approximately five percent bentonite Mr Michael Collins of the SJCEHD was present to observe the placement of the boring and well seals on July 8, 1994 Monitorinci Well Installation Wells U-1 through U-3 were constructed of Schedule 40 polyvinyl chloride (PVC) casing and 0 02-inch machine-slotted screen The annular space around the screen was packed with Lonestar #3 graded sand A two-foot thick bentonite seal was placed above the sandpack, and the remaining annular space sealed with neat cement The top of each well is protected by a water-resistant vault box set in concrete, a locking waterproof well cap, and a lock Well construction details are presented with the Logs of Boring in Appendix B Well Development The monitoring wells were developed by Gettler-Ryan Inc (G-R) of Dublin, is California, on July 21 , 1994. Each well was alternately surged with a bailer, then Report No 4627 703 5 3 GeoStrategies Inc.