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, <br /> TABLE 5 <br /> ESLS COMPARED TO SITE CONDITIONS <br /> ESL, Maximum soil <br /> Parameter m corncel�tration,m Location,Depth,Date <br /> Benzene 0.18 NIA NIA <br /> Toluene 9.3 1.3 MW-2 @ 20.5' 8/12/98 <br /> Ethylbenzene 4.7 0.11 MW-2 @ 28.5' 8/12/98 <br /> Xylene 1.5 4.2 MW-2 @ 20.5' 8/12198 <br /> TPHg 500 14,000 MW-2 @ 20.5' 8/12/98 <br /> TPH 400 870 MW-2&20.5' 8112198 <br /> Source:Table D,Interim Final--SF Bay RWQCB—duly 2003 <br /> The October 2004 CAP also compared groundwater analytical results to the environmental screening <br /> levels (ESLs) developed for the potential for chemicals in groundwater to volatilize and impact indoor <br /> air. Table 6 compares the maximum concentrations of petroleum constituents detected in groundwater <br /> to the Water Quality Objectives(WQO). <br /> TPHd and TPHg have been detected in groundwater samples collected from wells MW-2,MW-3, and <br /> MW4 at concentrations that exceed water quality objectives (WQOs) established by the Regional <br /> Water Quality Control Board, Central Valley Region (RWQCB). The WQOs for TPHd and TPHg are <br /> 100 micrograms per liter (ug/L) and 5 ug/L, respectively, and the WQOs are based on taste and odor <br /> thresholds for drinking water(Table 6). The concentrationsrecorded for MW-2 are associated with the <br /> free product that has periodically appeared in this well. <br /> TABLE 6 <br /> WQO's COMPARED TO SITE CONDITIONS <br /> WOO, Maximuth'groundwater <br /> Parameter ug/L concentration,u Location,Date <br /> Benzene 1.0 4.6 MW-2/Nov., 1998 <br /> Toluene 150 600 MW-3/June,2004 <br /> Ethylbenzene 300 N/A N/A <br /> Xylene 1750 19,000 MW-2/Sept.,2001 <br /> TPHd** 100. 240,000* MW-2/August,2004 <br /> TPHg** 5 370,000 MW-2/Sept.,2001 <br /> * indicates TPH i result with presence of free pnWuet <br /> ** WQO values for TPHg and TPHQ arc for taste and odor thresholds;values for benzene,toluene, <br /> ethylbenzene,and xylenes are California primary maximum contaminant levels(MCL's) <br /> 15 <br /> RX0NTGRAN1S1oekion\CAP\CAP ADDENDUM <br />