ARCHIVED REPORTS_XR0008240 - Laserfiche WebLink

Home Browse Search

2 0 GROUNDWATER MONITORING, SAMPLING AND ANALYSIS On February 19, 2003, to comply with quarterly groundwater monitoring requirements, Ramage Environmental monitored and sampled the three wells 21 Groundwater Monitoring Depth-to-groundwater was monitored using a water level indicator capable of measurements to within 0 01 foot The static depth to the groundwater table, as measured in the three monitoring wells, ranged from 14 58 feet below grade in MW-1 to 26 95 feet below street grade in MW-3 r rThe groundwater surface elevation in the three wells ranged from a high of 14 44 feet below mean sea level (msl) at MW-1 to a low of 15 39 feet below msl at MW-3 The resulting groundwater ' surface appears as a regular plane dipping to the northeast at a gradient of approximately 0 0112 foot/foot A groundwater surface contour map is included as Figure 4, and the groundwater monitoring data are summarized in Table 3 f 22 Groundwater Sampling and Analysis Following groundwater level measurements, the wells were purged and sampled The wells were purged with a pump and dedicated disposable tubing until at least three well casing volumes had been removed and/or after groundwater temperature, pH and electrical conductivity values had stabilized Groundwater was sampled from the wells using disposable polyethylene bailers and ' laboratory-supplied containers Each sample container was transported in an iced cooler with chain-of-custody documentation to Excelchem Environmental Labs (Excelchem), a state of California certified hazardous waste testing laboratory (Certification #2119) Excelchem analyzed ' each groundwater sample for TPH-as-gasoline and benzene, toluene, ethylbenzene, xylenes (BTEX) by EPA Method 8020/8015M, and for MTBE, di-isopropyl ether (DIPE), ethyl tertiary butyl ' ether (ETBE), tertiary amyl methyl ether (TAME), tertiary butanol (TBA), and 1,2-dichloroethane (1,2-DCA) by EPA Method 8260B Only the groundwater sample collected from MW-1 contained detectable concentrations of gasoline hydrocarbons This sample contained 18,000 micrograms per liter(µg11) of TPH-as- gasoline, 1,200 µg/l of benzene, 1,300 µg11 of toluene, 1,000 pg/l of ethylbenzene, and 3,200 µg11 of xylenes The groundwater sample analytical results are summarized in Table 2, the distribution ' of gasoline in groundwater is shown on Figure 5, and the laboratory reports are included in Appendix A 6