SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

maximum concentration the 1,951 gallons of wastewater released from the tank may have contained 1/50'h of a gallon of gasoline or slightly less than 1/4 of a cup of gasoline. Collection and Analysis of Water Samples from the Storm Drain System On February 27, 2003, David Threlfall, a WEGE geologist, met with Mr. Shawn Hart of the San Joaquin County Public Works Department and inspected the portion of the storm drain system that was impacted by unauthorized release on February 25, 2003. Mr. j Threlfall collected water samples from the small vaults beneath the storm drain gratings on the north side of Roselawn Avenue near the origin of the spill and at the intersection of Roselawn and Buena Vista Avenues. Mr. Threlfall and Mr. Hart also inspected the large storm drain vault and pumping facility located at the southern end of Buena Vista, approximately '/4 mile south of the intersection of Buena Vista and Roselawn Avenues. This vault receives all of the storm drain water from the aforementioned entry points. The water in the vault is eventually pumped into Smith Canal, which is located immediately to the south of the vault and associated pumping station. The vault and pumping facility are operated by Reclamation District #1614. According to Mr. Clyde James, Superintendent of District 1614, the pumping station is activated during storm events, and generally requires at least I/4 of an inch of precipitation in the area to initiate pumping. The water observed in the vault on February 27, 2003 was most likely an accumulation of water from the unauthorized release on February 25, 2003 mixed with a small amount of precipitation that occurred on February 26, 2003 along with the residual accumulation of wastewater since the last I pumping cycle. Mr. Threlfall collected one water sample from the vault and one sample of the sediment that had accumulated at the base of the concrete vault. The water samples were collected in 40-m1 VOA vials that were preserved with 0.5 ml HCL. The sediment sample was collected in a 2" X 6" aluminum sleeve. The ends of the sleeve were sealed with Teflon film and further protected with plastic caps. The soil and water samples were labeled and placed in an ice chest and maintained at 4 ° C. The samples were delivered to Kiff Analytical Laboratories with accompanying chain of custody documentation on February 28, 2003. Kiff Laboratories analyzed the three water samples and one sediment sample for concentrations of Total Petroleum Hydrocarbons as Gasoline (TPH-G), Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX), and Methyl-tri- butyl ether (MTBE) using 826QB. Kiff's analytical report is included as Attachment A to this report. EPA method yt p P None of the three water samples or the one sediment sample showed concentrations of TPH-G above the laboratory detection limits of 50 ug/L (water samples) or 1.0 mg/kg (sediment sample). None of the water or sediment samples showed the gasoline constituents Benzene, Ethylbenzene, or Xylenes above the laboratory detection limits of 0.5 ug/L(water samples) or 0.005 mg/kg(sediment sample). Toluene was detected in the water sample from the storm drain vault in a concentration of 0.54 ug/L,just exceeding the laboratory detection limit of 0.5 ug/L. Toluene was also detected in the sediment sample from the storm vault in a concentration of 0.1 mg/kg. The sediment sample 3 i