ARCHIVED REPORTS_XR0010782 - Laserfiche WebLink

Home Browse Search

1 Working to Restore Nature Semiannual Groundwater Monitoring, Second Half 1993 January 27, 1994 Quik Stop Market No 120, Stockton, California F7120 93 ' (TPHd), total petroleum hydrocarbons as gasoline (TPHg), and for benzene, toluene, ethylbenzene, and total xylenes (BTEX) Groundwater Sampling Groundwater samples were collected from on-site monitoring wells MW-1 through MW-3, in accordance with RESNXs groundwater sampling protocol (Appendix A) Groundwater purged from the wells and equipment decontamination water was placed in a licensed, ' trailer-mounted container and disposed of at Gibson Environmental, a licensed recycling facility located in Redwood City, California The volume of groundwater removed from each well is noted on the well purge data sheets included in Appendix B Laboratory Analyses ' The groundwater samples were transported to Sequoia Analytical Laboratories, a state- certified laboratory located in Redwood City, California Samples were analyzed for the presence of TPHd following modified Environmental Protection Agency (EPA) Methods 3510/3520/8015, TPHg following EPA Methods 5030/8015, and BTEX following EPA Methods 5030/8020 The laboratory analytical report and chain-of-custody record are attached in Appendix C Summary of Results ' A summary of the analytical results from current and past well samplings is presented Table 1 Plate 2 shows the groundwater elevation contours for December 17, 1993, based on the water level data in Table 1 Since June 18, 1993, the groundwater elevations fell an average of 0 32 foot, ranging from 0 30 foot in well MW-2 to 0 35 foot in well MW-3 The apparent groundwater flow direction for December 17, 1993, was to the east at a gradient of approximately 0 002 As shown in Table 1, TPHd, TPHg and BTEX have been nondetectable in groundwater samples collected from the wells at this site since March 1991 The next semiannual groundwater sampling and analysis is scheduled for June 1994 1 2