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. Ms. Carol Oz Project 791701.008 October 19, 1999 Page 2 Low residual concentrations of total petroleum hydrocarbons as gasoline, benzene, toluene, ethylbenzene, and total xylenes in soil remain at depths of 31 to 56 feet below ground surface. The highest detected dissolved petroleum hydrocarbon concentrations have historically occurred in well MW-1. The groundwater flow direction is generally east-southeast to east-northeast. SCOPE OF WORK Pinnacle supervised installation of the three soil borings (CPT-1, CPT-2 and CPT-3) using continuous push technology (CPT) on August 23, 24 and 26, 1999. Gregg Drilling, a California licensed drilling contractor, performed the CPT activities. The locations of CPT- 1, CPT-2 and CPT-3 are shown on Figure 2. Boring logs for CPT-1, CPT-2 and CPT-3 are included in Appendix A. Figure 3 depicts subsurface conditions and analytical results of soil and groundwater samples. . Task 1 - Prefield Activities After receiving workplan approval from the San Joaquin County Public Health Services, Environmental Health Division, Pinnacle submitted drilling permit applications and fees. Pinnacle also applied and received Encroachment Permits from City of Stockton for work in Alpine Street. Task 2 - Field Investigation The site investigation consisted of three CPT borings with soil samples collected at five- foot intervals to evaluate subsurface stratigraphy and collection of HydroPunch groundwater samples at shallow and deep intervals to evaluate the lateral and vertical extent of groundwater impacts. CPT-1 is located'eross gradient and north of the site within Alpine Street. CPT-2 is located directly downgradient of well MW-1 along the eastern property boundary and CPT-3 is located downgradient of VW-3 along the eastern property boundary. CPT locations are shown on Figure 2. CPT boreholes were grouted upon completion using bentonite grout pumped through CPT rods to the base of the boreholes. Separate borings were installed for collection of groundwater samples in CPT-2 and CPT- 3. Due to time constraints associated with encroachment in Alpine Street, groundwater samples were collected from the same boring as soil samples were collected. Groundwater sampling was attempted using HydroPunch sampling equipment from the first-encountered water-bearing zone at approximately 35 to 55 feet bgs and from the lower water-bearing CPIC:1Archive\Arco121861Reports12186p106.doe