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r September 26, 1996 Page 3 former used oil UST(GTI, June 28, 1994). Thirty seven soil "samples collected from the borings were analyzed. The maximum concentrations of TPHg and benzene(15,000 and 160 ppm) were reported in a sample from boring SB-4, in the former UST pit. Groundwater was reported at a depth of 43 feet bgs. In November and December 1995, GTI drilled four borings (SB-6, SB-7, SB-9, and MW-7), obtained groundwater"grab" samples from borings MW-7 and SB-9, and installed one groundwater monitoring well (MW-7)to further define the extent of hydrocarbons in soil and groundwater(GTI, January 25, 1996). GTI reported maximum concentrations of TPHg and benzene (640 mg/kg and 1.4 mg/kg,respectively) in a soil sample from 40-1/2 bgs boring SB-9. Results of groundwater grab sampling indicated 1,900,000 ppb TPHg in MW-7 and 260,000 ppb in boring SB-9. Benzene was reported as nondetectable in both groundwater grab samples. QUARTERLY MONITORING Quarterly monitoring has been ongoing at the site since March 1991. Historical groundwater gradient has been generally consistent to the southeast. Water levels have fluctuated in the wells from approximately 30 feet bgs recently to 47 feet bgs in 1992. Generally, groundwater levels have risen at the site since 1994. Blaine Tech Services, Inc. began monitoring at the site in November 1994;prior to that GTI performed the quarterly sampling. Nondetectable to low concentrations of hydrocarbons in Wells MW-3, MW-4, and MW-6 suggest that the hydrocarbon plume in groundwater has been defined in the areas north, northwest, and west of the former USTs. Hydrocarbon concentrations in Well MW-1, located west of the former USTs,have declined significantly over time. Hydrocarbon concentrations in Well MW-5, southeast of the site, have been relatively consistent over time. The highest concentrations of hydrocarbons in groundwater were recently reported in Well MW-7, southeast (downgradient) of the site, in which TPHg and benzene were reported at 9,700 and 350 ppb, respectively. During the most recent sampling, MtBE was detected in only one of seven wells sampled(15 ppb MtBE in offsite Well MW-5). PROPOSED SCOPE OF WORK The scope of work for this investigation has been proposed to further evaluate the extent of gasoline hydrocarbons in soil and groundwater offsite to the southeast (downgradient), and to initiate collection of data to assess the potential health risk associated with the existing hydrocarbon plume at the site. This work is described in more detail below. PACIFIC has prepared the attached Site-Specific Health and Safety Plan(Attachment B) required by the Occupational Health and Safety Administration(OSHA) Standard "Hazardous Waste Operations and Emergency Response" guidelines(29 CFR 920-078.I A/W PLAN