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GEOMATRIX Previous soil investigations were conducted at the Hanson Property by Aqua Science Engineers, Inc. (ASE) and Geomatrix in 1995 and 1996, respectively. Results from those previous investigations are summarized below. 2.1 AQUA SCIENCE ENGINEERS (MAY 1995) In May 1995, ASE performed an environmental assessment on behalf of Fremont Land, Inc., of Milpitas, California, to evaluate the presence of petroleum hydrocarbons in soil along the location of the former Old Valley Pipeline. Their findings were presented in a 24 May 1995 report titled, Project Report, Subsurface Soil Assessment, ASE Job No. 2857, Schulte and Chrisman Roads, Tracy, California. Eight test pits (A through H) were excavated along the former location of the pipeline (Figure 2) to a depth of 4 feet below ground surface (bgs) and soil samples were collected from the bottom of each test pit. Although the pipeline had been removed, there was visual evidence of a protective tar-like pipe wrap material in the soil at a depth of 3 feet bgs. No visual evidence of petroleum hydrocarbon staining or odor was observed in the excavated soil. Soil samples were analyzed for total oil and grease (TOG) using U.S. Environmental Protection Agency(EPA) Method 5502E and total recoverable petroleum hydrocarbons (TRPH) using EPA Method 5502F. Soil samples from four of the eight locations were non-detect for TOG and TRPH and samples from the remaining locations (Locations A, C, E, and H) contained concentrations of TOG ranging from 30 to 1600 milligrams per kilogram (mg/kg) and TRPH ranging from 20 to 890 mg/kg. Based on the lack of soil staining or odors, these detections were likely not due to petroleum hydrocarbons in the soil,but may have been associated with biogenic material or fragments of pipe wrap in the soil samples. The TOG and TRPH analyses are not sufficient to discriminate between petroleum hydrocarbons and other hydrocarbons (such as biogenic material or fragments of pipe wrap) that may be present in a sample. Analytical results for the eight soil samples collected at 4 feet bgs are presented in Table 1. 2.2 GEOMATRIX CONSULTANTS (SEPTEMBER 1996) To further assess the presence of petroleum hydrocarbons in the soil beneath the former pipeline, and to provide data to better explain those generated by ASE, Geomatrix conducted 1AWPD0CS\4097TADDLINVB.D0C 2