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t , o. yN A S S O C I A T E S I N C 2.0 METHODS AND PROCEDURES To evaluate the extent of impacted groundwater and determine the groundwater gradient at the site, three soil borings were advanced in the vicinity of the former USTs and completed as groundwater monitoring wells All field activities were performed in accordance with ATC's ' Workplan for Subsurface Investigation at Pack Coast Recreation, 3755 Munford Avenue, Stockton, California, dated September 24, 1998 This workplan was approved by PHS/EHD on September 25, 1998 with minor modifications ' 2.1 Soil Boring Advancement and Sam lin ' Drilling was conducted on November 10 and 11, 1998 by V & W Drilling (State C57 license no 720904) utilizing a hollow stem auger drill rig Soil borings MW 1, MW2, and MW3 were advanced and completed as groundwater monitoring wells A field geologist logged drill cuttings and soil samples utilizing the Unified Soil Classification System Descriptions of soil types encountered and sample collection intervals are included on the bonng/well construction logs contained in Appendix A The cored soil samples were collected at five-foot intervals or significant changes in lithology M using a 2-inch diameter split-spoon sampler containing three brass tubes The cored samples and drill cuttings were characterized for soil type, moisture content, and visual evidence of petroleum hydrocarbons A photoiomzation detection meter (PID) was used as a field screening device for the detection of petroleum hydrocarbon vapors in drill cuttings and cored samples Drill cuttings were temporarily stored on site in 55-gallon DOT approved steel drums ' 22.22 Soil Sample Analysis Selected soil samples were placed on ice, and transported under chain-of-custody to BC Laboratories (DOHS #1186) of Bakersfield, California for analysis All soil samples were analyzed for total petroleum hydrocarbons as gasoline (TPHg), benzene, toluene, ethylbenzene, and xylenes (BTEX) utilizing EPA 8015 and 8020 methodologies, and oxygenate fuel additives utilizing EPA 8260 methodology The analytical results for soil samples are summarized in Table 1 Laboratory data sheets and chain-of-custody documentation are included in Appendix B The laboratory data for soil sample PCR-MW3-40 5 is contained in Appendix D 2.3 Groundwater Monitoring Well Construction ' Soil borings NI W1, MW2, and MW3 were subsequently completed as groundwater monitoring wells to assess impacted groundwater beneath the site, and to provide measurement points for the ' determination of groundwater flow direction and hydraulic gradient The wells were surveyed on November 16, 1998 to an arbitrary elevation Survey data is contained in Table 2 Each well was constructed with 2-inch PVC casing The screened interval of each well was positioned from approximately 5 feet above to 15 feet below the encountered water table to allow w 1163931repoiUVumi doc 2 1