COMPLIANCE INFO - Laserfiche WebLink

Home Browse Search

Ms.Kristi Shelton Page 2 of 6 Current groundwater elevations are summarized in Table 1 and historical elevation data are summarized in Table 2. The groundwater gradient for this event is depicted on Figure 4. On February 4, 2011, depth to water and total well depth measurements were recorded for wells MW 1, MW2, MW3, MW4 and MW5. Prior to sample collection, a minimum of three well casing volumes were purged from each monitoring well. Groundwater samples were collected for analysis after water in the casing recharged to �80% of pre-purged levels. Groundwater samples were collected with dedicated disposable bailers, carefully decanted into the appropriated containers, checked for headspace, uniquely labeled, placed into an ice chest cooled to approximately 4°C, and transported to Argon Laboratories (Argon) in Ceres, California (ELAP No. 2359) under chain of custody protocol for analysis. Groundwater samples were analyzed for: • Total petroleum hydrocarbons as gasoline (TPHg) and Total petroleum hydrocarbons as diesel (TPHd)by EPA method 8015M • Benzene, toluene, ethylbenzene, and total xylenes (BTEX)by EPA method 8260B • Methyl tert-Butyl Ether (MTBE), Di-Isopropyl Ether (DIPE), Ethyl tert-Butyl Ether (ETBE), tent-Amyl Methyl Ether (TAME), t-Butanol (TBA), 1,2-Dichloroethane (DCA) and 1,2-Dibromoethane (EDB)by EPA method 8260B Purge water was contained in properly labeled Department of Transportation approved 55-gallon poly drums pending disposal. Current groundwater analytical data are summarized in Table 1 and historical groundwater analytical data are summarized in Table 2. Monitoring data sheets are included in Attachment A. Laboratory analytical results are included in Attachment B. RESULTS OF INVESTIGATION Monitoring Well Designations • MW 1: The core well and center of the groundwater TPHg/benzene plume. • MW2: The distal well located downgradient of MW 1 and contains the highest concentrations of DCA. • MW3: The lateral well located to the east-northeast of MW 1 with no analyzed petroleum hydrocarbon constituents detected. • MW4: The upgradient well with no analyzed petroleum hydrocarbon constituents detected. • MW5: The downsradient well with no analyzed petroleum hydrocarbon constituents detected. Groundwater Analytical Results Groundwater analytical results from the February 4, 2011 groundwater sampling event are summarized in Table 1 and briefly discussed as follows: G:\GROUNDZE\WCTOMATO\WCT-Investigation\Reports\QMR\2011\1 QM201 l.doc