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Field Investigation: SSI - Phase One 1 with a CME 75HT drilling rig using 8-inch The auger flights were steam-cleaned prior to each diameter hollow-stem augers operated by Mitchell use and the sampling equipment was cleaned with Drilling Environmental Corp , a Iicensed well a Iaboratory soap and double-rinsed prior to each driller from Rancho Cordova, California This rig use to minimize the possibility of cross- was operated in a half-mast mode inside the contamination between samples The borings 1 forklift shop to drill boring HP-3 As required, were logged under the direct supervision of a PHS/EHD was notified in writing of the scheduled registered geologist in accordance with the Unified drilling(HLA, 1998b) and a PHSIEHD Soils Classification System Boring logs are representative periodically was present onsite to presented in Appendix A Drill cuttings from the observe drilling and sampling activities during the borings and rinseate, development, and purge field investigation water were placed in DOT-approved 55-gallon 1drums, sealed and labeled with the accumulation Boring HP-1 was advanced to a depth of 21 0 feet date and will be disposed of in accordance with bgs just east of the former UST excavation (same state environmental and transportation regulations location as SECOR boring SB-9) At the request of the PHS/EHD representative, a second boring The lower sleeve of each soil sample was (HP-Ia)was drilled immediately adjacent to immediately sealed with teflon sheets, plastic end- boring HP-1 in order to collect a soil sample from caps,and tape, labeled, and placed in a chilled ice ' the 5 foot bgs sample depth This was done chest for later transport with a completed chain-of- because a Hydropunch sample (see below) had custody form to a state certified analytical been collected in the 3 5 to 7 5 foot depth Interval laboratory Chain-of-custody forms are presented precluding collection of the soil sample at 5 feet in Appendix D Soil-samples were screened in the bgs Boring HP-2 was advanced to a depth of 56 field using photoionizing detector(PID)equipped feet bgs in the center of the former UST with a 10 2 electron volt-rated lamp The PID was excavation(same location as SECOR boring SB- calibrated on a daily basis to a standard of 100 part 10) In accordance with the approved scope of per million isobutylene using PID readings are work, boring HP-2 was advanced beyond the documented on the boring logs PID readings, proposed depth of 30 feet bgs because field investigation objectives, and subjective field screening of soil samples suggested the presence criteria such as odor and soil discoloration were of organic vapors Boring HP-3 was advanced to a utilized to select samples for laboratory analysis depth of 25 5 feet bgs at a location inside the forklift shop At the request of onsite PHS/EHD In accordance with the approved scope, staff, HLA advanced the boring beyond the Hydropunch groundwater samples were collected proposed depth of 20 feet bgs,to collect an from each of borings (two from HP-1 and HP-2, additional soil sample and three from HP-2) Hydropunch samples were collected at depths of 3 5 and 22 0 feet bgs in HP- SoiI samples were collected at minimum 5 0 foot 1, at 3 5 and 26 5 feet bgs in HP-3, and at 4 5, 22 5 intervals with a California-modified split spoon and 31 0 feet bgs in HP-2 As previously sampler fitted with clean brass sleeves Samples discussed, the purpose of the Hydropunch samples were collected by advancing the boring to a point was to collect depth-specific groundwater ' immediately above the sampling depth,then analytical data The samples were collected in driving the sampler into the native soil through the accordance with the following procedures The hollow center of the auger The sampler was boring was advanced to just above the driven 18 inches with a standard 140-pound groundwater table or the designated sampling ' hammer dropped 30 inches The number of blows depths and the sampling tool was then pushed required to drive the sampler each successive 6- approximately 4 to 5 feet into the undisturbed inch interval was counted and recorded on the formational waters The tool was then retracted I boring logs to give an indication of soil which exposed approximately 1 to 3 feet of a consistency disposable dedicated screen,which remained in the ground The sampling rod at the surface was ' disconnected from the rig and a clean stainless L L300001387371WP`38737N19 Harding Lawson Associates 10