Laserfiche WebLink
Metadata
Document management portal powered by Laserfiche WebLink 9 © 1998-2015 Laserfiche. All rights reserved.
CV <br /> o <br /> V9 <br /> A S S O C I A T E S I N C . <br /> observed to be to the northeast. Regional groundwater flow is estimated to be in an easterly <br /> direction, based on San Joaquin County Flood Control and Water Conservation District data <br /> (Lines of Equal Elevation of Groundwater, Fall 1997). The groundwater gradient was calculated <br /> to be approximately 0.001 feet per foot or 5 feet per mile. . Groundwater monitoring data are <br /> presented in Table 1. <br /> Monitoring wells MW1, MW2, MW3, MW4, and MW5 were purged a minimum of three well <br /> volumes until the electric conductivity, pH, and temperature stabilized. Subsequent to purging, <br /> groundwater was sampled and transferred to appropriate sample containers, using a clean, <br /> disposable bailer with a bottom-emptying device to reduce volatilization. Sample containers <br /> were then labeled with sample identification, placed on ice, and shipped under chain-of-custody <br /> to Argon Laboratories. Field development/purge logs are presented in Attachment 1. <br /> Laboratory Analysis <br /> The groundwater sample from wells MW1, MW2, MW3, MW4, and MW5 were analyzed by <br /> Argon Laboratories (DHS'Cert. No. 2359) for total petroleum hydrocarbons as gasoline (TPHg), <br /> benzene, toluene, ethylbenzene, and xylenes (BTEX) by EPA Methods 801518020. Oxygenate <br /> fuel additives which include methanol, ethanol, t-butanol (TBA), methyl-t-butyl ether (MTBE), <br /> di-isopropyl ether (DIPE), ethyl-t-butyl ether (ETBE), t-amyl methyl ether (TAME), 1,2- <br /> dichloroethane (1,2-DCA), and 1,2-dibromoethane (EDB) were analyzed by EPA method 8260. <br /> Laboratory Results <br /> TPHg, benzene, ethyl benzene, toluene, and xylenes were not detected above their respective <br /> laboratory method detection limits. Oxygenate fuel additives were not detected above their <br /> respective laboratory method detection limits. <br /> Analytical results are summarized in Table 2. Laboratory data sheets and chain-of-custody <br /> documentation are provided in Attachment 2. <br /> DISCUSSION <br /> Based on past analytical results and field observations, soil and groundwater beneath the location <br /> of the former 500-gallon gasoline UST was moderately impacted by petroleum hydrocarbon <br /> constituents. Current results indicate that petroleum hydrocarbons have been reduced to <br /> nondetectable levels in the groundwater. The observations detailed in this report do not show <br /> that lateral migration of petroleum hydrocarbon impacted groundwater has occurred. <br /> wAwordpro117292.00021reportsl4 qmr 2001.doe <br />