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M. Scott Mansholt - 2 - 11 March 2008 TAOC Tracy Gravel Pits • Obtain groundwater samples onsite and offsite-downgradient (north) to delineate the lateral extent of affected groundwater; • Conduct a well search for groundwater wells in the vicinity of the site; and, • Collect a groundwater sample from the industrial water well northwest of the site. Geomatrix completed 98 trenches, on approximate 100-foot spacing, to depths of 10 to 15- feet, generally in the northern two-thirds of the site, from the former gravel pit excavation to the north-northeast property boundary. The trenching program (conducted mid-June 2007) was designed to supplement previous findings. Up to four soil samples were collected from each excavation and submitted for analysis of TPH as diesel (TPHd), TPH as motor oil (TPHmo), and PAHs; nine soil samples between 1 and 1 .5-feet and one sample from 10-feet were analyzed for Title 22 metals. During August 2007, Geomatrix completed nine cone penetrometer test (CPT) borings, three onsite and six offsite, downgradient to the north in the adjacent residential neighborhood. Groundwater was first encountered onsite at between 48 and 53-feet and offsite at between 50 and 58-feet. The maximum CPT depth achieved was 70-feet to evaluate the vertical extent of affected groundwater. The nine groundwater samples were analyzed for TPHd, benzene, toluene, ethylbenzene, and xylenes (BTEX), and PAHs. In addition, the groundwater samples were submitted for general minerals analysis to evaluate the water quality parameters. Geomatrix conducted an additional well search of Department of Water Resources (DWR) to supplement the previous search. RESULTS - SOIL Based on the field observations and analytical results, Geomatrix classified the TPH material present into four different categories: 1. Oily waste material- primarily at a distinct depth between 2 and 4-feet and in 6 to 12- inch layers: consisted of viscous and tar-like with an odor; 2. Oily debris material— a mix of the oily viscous waste material and fragments of wood, metal, bricks, glass, and other debris; Geomatrix believes the areas where this material was identified were former pits for trash disposal mixed with oily waste; 3. Asphaltic material— hardened asphalt-like TPH (brea) material mixed with gravel to 7-feet in 0.5 to 3.5-foot layers, appears to be from drying and/or the result of burning the petroleum material and found mostly within the linear gravel excavation and the north-central part of the site; 4. Surface deposits — small, 1 to 6-inch diameter pieces of the hardened brea material described above and scattered across the ground surface; found near 42 trenches