ARCHIVED REPORTS XR0000040 - Laserfiche WebLink

Home Browse Search

1 . 2.0 GROUNDWATER MONITORING, SAMPLING AND ANALYSIS 1 , On March 7, 2003, to comply with quarterly groundwater monitoring requirements, Ramage Environmental monitored and sampled the three wells 21 Groundwater Monitoring Depth-to-groundwater was measured using a water level indicator capable of measurements to ' within 0 01 foot The depth to the groundwater table, as measured in the three monitoring wells, ranged from 44 75 feet bgs in MW-2 to 45 20 feet bgs in MW-3 The corresponding groundwater ' surface elevations in the three wells ranged from a high of 23 66 feet below mean sea level (msl) at MW-2 to a low of 23 96 feet below msl at MW-3 The resulting groundwater surface appears as a regular plane dipping to the north at a gradient of approximately 0 00231 foottfoot A ' groundwater surface contour map is included as Figure 3 The well construction details, wellhead elevations and groundwater monitoring data are summarized in Table 5 ' 22 Groundwater Sampling and Analysis lie 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 (#2119) Excelchem analyzed each sample for TPH-as-}et fuel, TPH-as-gasoline and benzene, toluene, ethylbenzene, xylenes (BTEX) by EPA Method 8020/8015M, and for methyl tertiary butyl ether (MTBE), di-isopropyl ether (DIPE), ethyl tertiary butyl ether (ETBE), tertiary amyl methyl ether (TAME), and tertiary butanol (TBA) by ' EPA Method 82608 ' The groundwater samples collected from all three monitoring wells contained detectable concentrations of petroleum hydrocarbons The highest concentrations were detected at MW-1 This sample contained 120 micrograms per liter (pg/1) of TPH-as het fuel, 7,300 µg/I of TPH-as- rgasoline, 1,600 µg/l of benzene, 38 µg/I of toluene, 170 µg/I of ethylbenzene, and 180 µg/I of xylenes MTBE was not detected in any of the groundwater samples The groundwater sample ' analytical results are summarized in Table 4, the concentrations of petroleum hydrocarbons in • groundwater are posted on Figure 4, and the laboratory reports are included in Appendix A 5 1