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© - 8 GeoSo1Vp f.LC- fydr®geologic ltavest�gatlon for Nunan ego-a9 VO 217-- LOCA'ON AMD [C-SC ver ON ' The subject site is located in downtown Lockeford, CA(See Figure 2 gar Site 0acuflen Map). It was previously used as a gasoline service station which housed four pump 1 dispensers with associated piping, three gasoline USTs, and one waste oil UST. Most of the site is covered by asphalt except for the concrete slab under the building and in the vicinity of the former dispenser islands. The site is basically flag 1 and surface drainage appears to flow to the alley way at the south end of the property. VIOr2a A f ar s 0ya'-aD Potential groundwater monitoring well locations were marked at the site in white paint. Underground Service Alert was contacted prior to drilling. Each soil boring location was screened with a magnetometer and was then hand angered to a depth of 5 feet bgs prior to excavation with the auger drill rig to avoid damage to the high density of underground piping and utility lines. The soil boring locations were placed onsite and outside the perimeter of the previously encountered soil contamination. The soil boring location for MW-2 had to be moved further to the east to avoid an overhead power line adjacent to a previously unmarked PG&E gas line. Three (3) soil borings were excavated and converted into groundwater monitoring wells in the vicinity of the gasoline contamination identified during UST removal and previous subsurface investigations. NETHOD OF ORGLLING AND SAWPUNG CF SOIL The soil borings for groundwater monitoring wells MW-1, MW-2, and MW-3 were excavated with an eight (8) inch hollow-stem auger drill,with 5-foot long sections to depths of 120 feet, 100 feet and 98 feet below ground surface (bgs), respectively. Soil samples were collected with a two (2) inch inner diameter, three (3) foot long, split spoon sampler in the upper eighty feet bgs depending upon the soil stratigraphy and contaminants encountered. Soil samples were collected with a two & one-half (2 '/s ) inch inner diameter,five (5) foot long,split spoon sampler below 80 feet bgs in MW-2 and MW-3 and 101 '/s feet bgs in MW-1 when performing continuous coring to define the thickness of the perched groundwater zone. The soil samples were obtained by the compressive force of a 140 lb hammer dropped from a height of 18 inches. The soil samples were extruded into six(6)-inch long steel sample liners. Soil within sample liners, collected from depths where there was obvious olfactory and/or visual evidence of hydrocarbon contamination,was scraped into a plastic Zip-Loc bag so that a small volume of disturbed soil could release hydrocarbon volatiles into the bag for approximately two to five minutes. A properly calibrated photo ionization detector (PID) was used to screen the soil samples, inside each bag, for the presence of gasoline constituents. Corresponding undisturbed soil samples in liners which were collected immediately adjacent to the disturbed samples with the highest PID readings,were selected for further laboratory analysis. Each soil sample collected was covered at each end of the metal cylinder with Teflon sheets, plastic end caps, and sealed with duct tape to adhere the caps 05-03_2000 Ge®Soly, LLC-flydrogeologlc lnvesiigation for Nunan Page 2 of 10