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i 'vIr. I I Scott Mansholt—Chevron Environmental/Management Company May 26, 2004 Sunztnary of f=ield Activities. SSJID Pipeline Page 2 of 3 Lthyibenzene and total xylenes were detected in the soil sample collected from the stockpiled soil. Concentrations of TPPH were detected in all four samples analyzed at concentrations ranging From 190 to 2,400 mg/kg. The highest TPPH concentration was detected in the soil sample collected from the north end of the bore pit at an approximate depth of 14.5 feet bgs. The highest TEPH concentration was detected in the soil sample collected form the southern end of the bore pit at a depth of approximately 12 feet bgs. Following completion of the soil sampling and evaluation of the chemical data. Kleinfelder recommended to Nolte that a qualified health and safety person be consulted prior to continuation of the water main installation. Stockpiled soil generated during the bore-and-Jack pit excavation was covered with plastic sheeting pending disposal. SAIC was requested by Chevron Environmental Management Company to observe the SSJID excavation to assist in identifying soil not suitable for reuse as backfill. This letter report summarizes SAIC's activities during the SSJID project. FIELD ACTIVITIES SAIC began work at the SSJID excavation February 4,2004, during the construction of the bore- and-Jack pit in preparation for the 30-inch diameter water main installation beneath the UPRR ROW. The bore-and-jack pit was constructed approximately 75 feet north of the UPRR track. The horizontal boring for the SSJID water main extended approximately 200 feet south as shown on Figure 2. SAIC staff was present to direct the segregation of affected soil, to document the conditions of the soil, and to photograph the excavation activities. SAIC field staff recorded the presence and degree of affected soil observed in the trench and noted other soil characteristics of importance. Because the shored pit provided limited visibility of the pit walls,soil cuttings were observed from outside the trench and observations were recorded in a field logbook. Based on trench observations recorded during the initial excavation activities of the bore-and-jack pit,affected soil extended from an approximate depth of 14 to 16.5 feet bgs. The vertical extent of affected soil could not be determined. AIong the southern sidewall of the bore-and-jack pit, visibly affected soil was first encountered at the face of the sidewall of the borehole and extended approximately 10 feet into the borehole. Non-affected soil identified as clay was observed from approximately 10 to 120 feet into the borehole. From 120 to 175 feet, affected soil (clay) was . again observed in the borehole. Non-affected soil was observed from 175 to 200 feet into the borehole, which terminated at the receiving pit as shown on Figure 2. During excavation activities, groundwater was not encountered in the bore pit. Affected soils were temporarily stockpiled adjacent to the bore-and-jack pit north of the UPRR track. The stockpile area was prepared by placing 10-mit plastic sheeting on the stockpile floor overlapping an earthen berm. This structural control created an impervious barrier to precipitation and runoff containing any affected fluids in case of a significant storm event. The stockpile was maintained nightly by covering with plastic sheeting and sand bags. The bore-and- jack pit was covered with steel plates nightly so that the northbound lane of Banta Road could be opened, allowing traffic to resume a normal pattern. t All stockpiled soil and other designated waste was removed by Sturgeon& Sons (S&S)of Richmond,California, and disposed of at Forward Landfill in Manteca, California. Approximately 219 yards of affected soil was segregated and disposed of at Forward Landfill. Once affected soil was removed, S&S began to decommission the stockpile area by removing the 1 structural controls and plastic sheeting covering the stockpile floor. The stockpile area was