SITE INFORMATION AND CORRESPONDENCE

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GEOMATRIX groundwater sampling, and analytical methods are described in Sections 2.3.1, 2.3.2, and 2.3.3, respectively. 2.3.1 Soil Sampling Between August 6 and 15, 2003,Resonant Sonic International, Inc., of Woodland, California, advanced eight soil borings (SB-15 through SB-21 and SB-17A) on- and off site with oversight by a Geomatrix field geologist. Borings were advanced to depths ranging from 15 to 100 feet bgs using a Rotosonic rig 114 equipped with a 4-inch outer-diameter drive casing. Boring f depths were based on field observations of petroleum hydrocarbon-impacted soil. Drilling and soil sampling equipment was cleaned prior to being used at each boring location. Soil samples were collected continuously from each boring using a continuous core system (3-inch diameter by 5-feet in length). Soil cores were logged by a Geomatrix geologist in accordance with the Unified Soil Classification System as presented in the American Society of Testing and Materials (ASTM) Standard D2488-90. Recovered soil was screened in the field for organic vapors using a photoionization detector(PID). Soil samples were also examined for indications of petroleum hydrocarbons, i.e., petroleum odor and/or staining/discoloration L.J (greenish gray color). Boring logs are included in Appendix B. lA minimum of three soil samples were collected for laboratory analysis from each of the l on-site borings SB-15 through SB-17 and SB-21. Soil samples were collected at depths of approximately 1 and 5 feet bgs to evaluate the presence of petroleum constituents in shallow soil. Up to two samples were collected from deeper depths to evaluate the vertical extent of petroleum impact from about 40 to 60 feet bgs. Additional soil samples were collected from S13-17,including one at a depth that correlated with the most affected soil observed(e.g., high `�. PID readings, petroleum odor, and/or soil discoloration) within the soil column (at about 24 feet bgs) and two samples at the terminus of the boring to evaluate the vertical extent of affected soil (at about 56 and 68 feet bgs). The terminus samples were collected from depths below which field observations and/or screening results did not indicate the presence of petroleum constituents. A minimum of two soil samples were collected for laboratory analysis from each of the off-site -� borings SB-18 through SB-20. The primary purpose of these three borings was to delineate petroleum-affected soil hydraulically downgradient of the site. Shallow samples were not collected from these off-site borings because there was no evidence of petroleum-impacted soil from ground surface to about 56 feet bgs. A soil sample was collected from the depth interval 1:%eaoiecn 00N%5o1 LOWU011-03.d.� 6 t