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F- 41 F The soil sample collected from the excavation GEOMATRIX for the water line was analyzed for fingerprint charac- terization using capillary gas chromatography (GC) and thin layer chromatography (TLC). The GC characterization results indicated petroleum hydrocarbon in the soil sample to be a heavily-degraded material with a boiling range similar to a diesel #2 (282°C to 338°C) and a lesser amount of a heavier material with a boiling range above 450°C. The TLC characterization indicated the material was F, highly insoluble. The GC chromatogram for the excavation sample is similar to GC chromatograms from the Dividend property. The GC chromatogram for the excavation sample and a GC chroma- togram for a sample collected at the Dividend property are included in Appendix A. 1990 Groundwater Assessment i { In May 1990, L•F performed a groundwater assessment at the site on behalf of Sunboro Development FCorporation. Results of the assessment were presented in the L•F 27 July 1990 "Report on Ground- ' Water Quality Investigations, Sunboro Development Corporation Parcel B, Tracy, California." Four groundwater monitoring wells, ranging in depth from 15 to 18.5 feet bgs, were installed at the site. The Felevation of the groundwater surface ranged from about 29 to 31 feet above mean sea level. The groundwater gradient was reported as 0.0083 to the southwest. Soil samples were collected from the borings, and two samples from each boring were analyzed for total petroleum hydrocarbons (TPH) F quantified against a diesel standard and a motor oil standard using a modified version of EPA Method 8015 and for benzene, toluene, ethylbenzene, and xylenes (BTEX) using EPA Method 8020. Soil ana- Flytical results are summarized in Table .1. TPH, benzene, ethylbenzene, and xylenes were not detected a in the soil samples. Toluene was detected in all soil samples at low concentrations ranging from 0.015 to 0.18 mg/kg. Fi L•F collected groundwater samples from the groundwater monitoring wells on 7 June 1990. Ground- water samples were analyzed for TPH using a modified version EPA Method 8015 and for BTEX using EPA Method 8020. Groundwater analytical results are summarized in Table 2. TPH and BTEX were f not detected in the groundwater samples, with the exception the sample collected from well MW-I with a toluene concentration of 0.3 micrograms per liter(ltg/f). P 2.2 Soil and Groundwater Assessments at Dividend Property P I'tY Soil and groundwater quality have been investigated by multiple parties at the Dividend property (APNs 238-02=10/13/14) since 1989. Most recently, Gcomatrix has completed soil assessments and groundwater monitoring during 1994 and 1995 on behalf of CPL in support of completing a human 0 health risk assessment for approval by the California Environmental Protection Agency—Department of Toxic Substances Control (DISC) and is working with the California Regional Water Quality Con- trol Board—Central Valley Region (RWQCB) to obtain site closure. In summary, subsurface soil is F! affected by degraded petroleum hydrocarbons (crude oil/Bunker C) between depths of 5 and 16 feet at several locations along the southern property boundary, parallel to and adjacent to a former pipeline. The highest concentrations generally occur at 7 to 10 feet bgs, coincident with the groundwater surface. 13 3 F