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Chevron Environmental Management Company Soil and Groundwater Investigation Report Tracy Byron Road Project interval, and the soil boring was terminated. While advancing boring SB-4, limited soil recovery was attained during the retrieval of the Macrocore above first encountered groundwater. In this case, only the bottom soil sample was collected. In several other borings, SAIC was not able to submit samples due to limited or no recovery(SB-14, SB-27, SB-30, and SB-31) or residual petroleum-affected soil(SB-22) present at that depth. 4.3.2 Grab Groundwater Sampling SAIC collected grab groundwater samples from select boring locations for analysis of petroleum constituents. The grab groundwater samples were collected approximately every 300 linear feet from dedicated Hydropunch borings advanced 1 to 2 feet away from a soil boring location. The primary soil boring was first completed to the total depth and data/observations collected from that boring were used to determine if a grab groundwater sample was to be collected at that location and the depth of sample interval. If SPO or an affected soil interval greater than approximately 2 or 3 feet thick were observed in the primary boring, a grab groundwater sample was not collected at that location. Beginning with sample GW-8-13 (soil boring number 8, groundwater sample collected at 13 feet bgs), grab groundwater samples were collected just below first encountered groundwater. In one case, sample GW-26-27,the RWQCB requested that a depth-discrete grab groundwater sample be collected for vertical groundwater delineation. For that purpose sample GW-26-27 was collected adjacent to boring SB-26 at a depth of 27 feet bgs. The grab groundwater samples were collected using a Hydropunch tool consisting of a disposable tip installed at the end of a hollow drive rod. The rod was pushed into the ground to a depth,just beneath first encountered groundwater(approximately 12 to 13 feet bgs),that would provide sufficient groundwater for sample collection. New polyvinyl chloride (PVC)well screen was installed within the hollow drive rods and then the rods were partially withdrawn(2 to 4 feet) from the borehole, exposing the well screen for sample collection. Grab groundwater samples were collected from the temporary well screen using a clean stainless steel bailer and decanted into laboratory provided bottles. SAIC collected 15 grab groundwater samples for analysis of petroleum constituents. Immediately upon collection,the grab groundwater samples were labeled and placed in an ice-cooled chest pending analysis. The only exception to this protocol was the first grab groundwater sample collected from boring SB-4. In this case,temporary well screen was installed in the primary borehole to first encountered groundwater and a grab groundwater sample was collected using the stainless steel bailer. The grab groundwater sample was decanted into laboratory provided bottles. After collection of the first grab groundwater sample, SAIC changed sample collection methodology by using a Hydropunch to collect additional grab groundwater samples. In all cases the stainless steel bailer and all down-hole probing equipment were decontaminated between borings. 5. RESULTS 5.1 SOIL SAMPLE ANALYSES All selected soil samples were submitted for chemical analyses to Lancaster Laboratories (Lancaster) in Lancaster, Pennsylvania(State-of-California certified laboratory#2116)under SAIC chain-of-custody procedure. Selected soil samples were analyzed for benzene, toluene, ethylbenzene, and total xylenes (BTEX)by EPA Method 8021B, total petroleum hydrocarbons quantified as crude oil (TPHc; C10—C36) by EPA Method 8015 Modified, and polynuclear aromatic hydrocarbons (PAHs)by EPA Method 8270 C with selective ion monitoring(SIM). 5.1.1 Soil Sample Analytical Results Concentrations of TPHc were not detected above the laboratory reporting limit in 6 of the 36 borings (SB-1, SB-4, SB-7, SB-20, SB-29, and SB-31). Concentrations of TPHc greater than 100 milligrams per 5