ARCHIVED REPORTS XR0003369 - Laserfiche WebLink

Home Browse Search

Fourth Quarter 1999 Monitoring and Sampling Report 2 7-Eleven, Inc., Store#14117.2725 Country Club Boulevard,Stockton,CA January g 2000 Monitoring Well Sampling and Analytical Results ' On November 24, 1999, groundwater samples were collected from groundwater monitoring wells: MW-1, MW-2, MW-3, and MW-4. Before sampling, at least four well-casing volumes of water was removed from each well. The groundwater samples were collected using disposable bailers. Groundwater samples were ' placed in 40-milliliter glass vials, which were acidified with hydrochloric acid to preserve the samples. The samples were then sealed using Teflon septum caps, labeled with the job identification number, the sample ' number, date, time, and type of laboratory analysis required. The samples were stored on ice and transported with a chain-of-custody record to a state-certified laboratory for analysis. The groundwater samples were analyzed for BTEK, MTBE and TPH-G using Environmental Protection Agency (EPA) methods 8021 Blmodified 8015, and for oxygenates MTBE, TBA, DIPS, ETBE, and TAME using EPA method 8260B. The analytical results for groundwater samples collected on November 24, 1999, are summarized in Table 1. Dissolved benzene, MTBE and TPH-G concentrations ranged up to 714 micrograms per liter (pg/L), 2,370 pg/L and 7,280 pg/L, respectively. Highest MTBE levels were reported in well MW-2 located in the underground storage tank pit (UST) area, whereas highest benzene and TPH-G concentrations were detected in downgradient well MW-4, and well MW-3 (located crossgradtent from the pump island and lormer USTs) The laboratory analytical reports for the groundwater samples are included in Attachment 4 Dissolved oxygen data taken from the monitoring wells on November 24, 1999 indicate enerali anaerobic Y9 9 9 Y ' conditions Dissolved oxygen levels ranged from 1.1 milligrams per liter (mg/L) to 1.9 mg/L (Table 1). Purge Water Transportation and Disposal All purge water generated during this quarterly monitoring and sampling event was stored in 55-gallon Department of Transportation (DOT)-approved drums pending characterization and proper disposal. Waste disposal documentation will be forwarded once received 1