Laserfiche WebLink
A S S Q C I A T E S I N C <br /> 4.2 Groundwater <br /> Elevated petroleum hydrocarbon analytes were detected in the water samples collected from wells <br /> MW1, MW2, MW3, MW6, and MW7 TPHg concentrations ranged from 1,600 parts per billion <br /> ' (ppb) to 90,000 ppb BTEX concentrations ranged from 14 ppb to 30,000 ppb The samples <br /> collected from wells MW4 through MW7 did not contain detectable concentrations of oxygenate <br /> fuel additives, but detection limits were elevated in several samples due the presence of elevated <br /> concentrations of petroleum hydrocarbons <br /> ' The horizontal extent of impacted groundwater at the site has been defined to the west The <br /> extent of impacted groundwater to the south can not be determined without installing a <br /> groundwater monitoring well in Oak Street Well MW6 contained detectable concentrations of <br /> ' TPHg and BTEX, but the concentrations of BTEX were relatively low Isoconcentration maps <br /> showing the lateral extent of impacted groundwater for TPHg and benzene are shown on Figures <br /> ' 7 and 8, respectively <br /> 5.0 WELL SURVEY <br /> At the request of the PHS/EHD, ATC conducted a search of the Department of Water Resources <br /> ' (DWR) groundwater well construction logs to identify any groundwater wells located within <br /> 2,000-foot radius of the site The search revealed ten wells located in the vicinity of the site <br /> ' None of the ten wells are located close enough to the site to be considered potential receptors <br /> The well locations are shown on Figure 9 The wells were located on the map according to <br /> "well location" description information provided on the well construction logs The well <br /> 1 construction logs are contained 1n Appendix F. <br /> ' The well located on the southeast comer of Poplar Street and San Joaquin Street (Well No 2) <br /> is the closest to the plume (within approximately 800 feet of the plume). The well is <br /> ' approximately 500 feet deep and is screened from 252 feet to 530 feet bgs. The petroleum <br /> affected shallow aquifer extends to 28 feet bgs, and no petroleum hydrocarbons were detected <br /> ' in soil samples collected from boring SB8 at 45 5 feet bgs, the maximum depth explored <br /> An on-site search for potential receptors was conducted on March 27, 1998 by ATC personnel <br /> No open ponds or streams were located within 100 feet of the plume. <br /> w 162596VepoFU\phupsi dm 6 <br /> 1 <br />