ARCHIVED REPORTS XR0008270 - Laserfiche WebLink

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Problem Assessment Report for 5or1 and Groundwater Contamination Corrigan Property (Project No W0541 00) and MW3 indicate a rise of the groundwater table since the last monitoring in October 1992, ' averaging 3 52 feet (Table 3) A groundwater gradient map was created using the January 27, 1993 data. Groundwater flows to the east at a gradient of 0 0071 ft/ft or approximately 37 ft/mile (Figure 8) Prior to sampling, at least 12 well casing volumes of water were purged from each well. Groundwater samples were collected from the three wells after stabilization of pH, electrical conductivity (EC) and temperature The samples were collected using dedicated, disposable bailers The samples were sent to State -certified RONA Environmental Laboratories in Fremont, California Collected water samples were analyzed for benzene, toluene, ethylbenzene, and xylenes (BTEX) using EPA method 8020 and total petroleum hydrocarbons ' as gasoline (TPHG) and diesel (TPHD) using EPA method 8015 All purged water was contained in DOT approved drums and left on site pending laboratory ' analyses Field purge logs are included as Appendix I ' Laboratory analyses determined that no petroleum hydrocarbon constituents were present in the samples collected from wells MW I, MW2, and MW3. Laboratory reports and chain -of -custody ' documents are presented in Appendix lI Table 2 summarizes laboratory results for groundwater since March 1991 ' 4.2 Drilling On January 28, 1993 RONA supervised the drilling of five additional soil borings (SB3 through SB7) in the vicinity of the former tanks as shown on Figure 10 Drilling was conducted by ' Spectrum Exploration, Inc. (C57# 512289) utilizing a hollow stem auger drill ng A field geologist continuously logged all drill cuttings and cored soil samples utilizing the Unified Soil ' Classification System Descriptions of soil types encountered and sample collection intervals are PAR -0393 FNL 4