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Mr. Ron Rowe March 9, 1998 Page 2 At each CPT Iocation, an initial CPT hole was advanced using an electronic piezocone tip. The piezocone tip measured cone bearing, sleeve friction,and dynamic pore pressure at 5 centimeter intervals. At selected depth intervals, pore water pressure measurements were monitored over time to determine relative hydraulic conductivity and hydrostatic head in the formation adjacent to the tip. A second CPT hole was advanced adjacent to the first for the purpose of collecting depth discrete groundwater samples from water-bearing horizons identified using interpreted date from the initial CPT boring. Groundwater samples were collected using a Hydropunch sampling tool. Groundwater samples were analyzed for total petroleum hydrocarbons as gasoline (TPHg), benzene, toluene, ethylbenzene, and xylenes (BTEX), and methyl tertiary butyl ether (MTBE) by EPA Methods 8015 (modified) and 8020, respectively by a state-certified laboratory on an overnight(15-hour)rush basis or a standard 5-day basis. An initial CPT sounding(CPT-1)was advanced within the former underground storage tank(UST)excavation on December 29, 1.997 by Gregg In Situ, Inc. (Gregg) of Martinez, California under the supervision of a SECOR geologist. This CPT location was located directly adjacent to the MW-7 well cluster. Two depth discrete groundwater samples were collected from CPT-1 using a Hydropunch sampling tool. The first sample was collected from approximately 84 feet bgs to confirm the groundwater analytical results reported for well MW-7-D and the second sample was collected from.approximately 106 feet bgs. The total depth of CPT-1. was 125 feet bgs. A copy of the cone penetration test data is included as Attachment A. Both groundwater samples from CPT-1 were analyzed by Superior Analytical Laboratory(Superior)for TPHg, BTEX, and MTBE on a 15-hour rush basis. Analytical results recieved on December 30, 1997 revealed the presence of a relatively high TPHg concentration in the groundwater sample collected at 106 feet bgs. A deeper groundwater sample was not collected at CPT-1 because no significant water bearing sand or gravel units were encountered between 106 feet and the total depth explored. (125 feet). Alternatively,a decision was made to collect a soil sample from the fine-grained soil horizon encountered between 1.016 and 125 feet bgs. On December 30, 1997, a third CPT hole was advanced near,the original CPT-1 sounding and a soil sample was collected at 125 feet bgs. The soil sample was analyzed for TPHg,BTEX,and MTBE by Superior on a standard 5-day basis. On December 30, 1997,soundings CPT-2 and CPT-3 were advanced in the anticipated downgradient direction from CPT-1 by Gregg. The CPT-2 sounding is located in the southeast corner of the Site and the CPT-3 sounding is located in the northern corner of the Site. The CPT-2 sounding was advanced to a depth of 115 feet bgs. Three depth discrete groundwater samples were collected from CPT-2 at approximate depths of 32, 82, and 102 feet bgs. The CPT-3 sounding was advanced to a depth of 120 feet bgs. Two depth discrete groundwater samples were collected from CPT-3 at approximate depths of 49 and 92 feet bgs. The five groundwater grab samples collected from CPT-2 and CPT-3 were analyzed by Superior for TPHg,BTEX,and MTBE on a standard 5-day basis. FINDINGS Stratigraphy and Hydrogeology Soils beneath the Site were investigated to a maximum depth of 125 feet bgs(CPT-1)during this investigation. Interpretation of soil types from near ground surface to the maximum depth explored are based on CPT-derived data and not from actual visual examination of samples. However, lithologic information collected from CPT- 1 was similar to the soil types visually observed during the advancement of the exploratory boring for well I MW-7. I . H:ISFFBIST0CKT0MCPTSURV2.RPT SECOR International Incorporated