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File No. 20-1147-56.6ef Nwpf k'q KLEINFELDER August 25, 1994 bottom, a sample of native soil was obtained by a Kleinfelder geologist from the backhoe bucket. Soil samples were obtained by scraping away about 4 inches of the soil in the backhoe bucket with a hand trowel, then driving a clean brass tube into the native soil. Sample tubes were decontaminated prior to sampling by washing in a solution of trisodium phosphate (TSP), followed by a distilled water rinse. Each tube was retracted, capped with Teflon sheeting and tightly fitting plastic end caps. Samples were labeled, logged on a chain- of-custody and stored on ice until delivery to California Analytical Laboratories/Enseco in West Sacramento, California. A representative from the SJCEHD, Ms. Kasey Foley, was present throughout the sampling process. Sample 31034 was taken from the west end of the excavation, and sample 31035 was obtained from the east end. Both samples were taken at approximately 8.5 feet below ground surface. The soil consisted of a medium brown, moist, silty clay. A photionization detector (PID) was used in the field to screen the soil for volatile organic constituents. Neither of the two soil samples showed PID readings above ambient background levels. The samples were analyzed for total petroleum hydrocarbons extractable (Method 3550) by GC-FID; and benzene, toluene, ethylbenzene, and xylenes by EPA Method 8020. The samples were analyzed on a one-week, rush, turnaround schedule. Of the analyses requested by the SJCEHD, only one constituent was present above a laborato re ortin limit. Sample 31035 (east end of the tank) had 110 mg/kg total petroleum hydrocarbons as diesel. On March 10, 1989, the area where sample #31035 was collected was excavated to approximately 14 feet bgs and 20 cubic yards of contaminated soil removed. Two soil samples (#22926 [bottom sample at 14 feet bgs] and #22927 [north sidewall at 13.5 feet bgs]) were collected from the excavation. SJCEHD staff observed hydrocarbon odors and soil discoloration from 8 to 11 feet. The excavation was advanced beneath the discolored soil, where samples were collected. The laboratory results from the samples collected did not report contamination; however, the laboratory noted on sample # 22927 that late eluting, unresolved hydrocarbons in the range of C15 to Cts could not be quantitated with the method used. The soil sample did not contain diesel as stored in the tank and Kleinfelder did not recommend additional investigation. The results of the sampling were submitted to the SJCEHD in 1989 for their review and approval. In 1994, SJCEHD reviewed their files and requested additional assessment. ETH:md 14194 Copyright 1994 Kleinfelder, Inc. Page 2 of 6