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1 Y <br /> Mr.Nuel Henderson <br /> Re: 102 S. Wilson Way-Petition for Closure Page 5 <br /> • Although the majority of wells show evidence of contaminant migration from <br /> another source,the data from Monitoring Well No. 4(included in Table I below) <br /> dramatically illustrate this point. <br /> Table 1: Data from Monitoring Well 4 <br /> Source: Ground Zero Analysis <br /> Date TPHR Benzene Toluene Eth 1 benzene Xylenes MTBE <br /> 5/16/1995 <50 22 <0.5 <0.5 <0.5 <br /> 11/9/1995 240 21 <0.5 <0.5 <0.5 <br /> 2/8/1996 240 <0.5 <0.5 <0.5 2.9 <br /> 4/24/1996 130 <0.5 <0.5 <0.5 <0.5 - <br /> 8/7/1996 210 <0.5 <0.5 <0.5 1.8 <br /> 11/5/1996 480 <0.5 3.0 <0.5 <0.5 <br /> 2/5/1997 560 76 <0.5 <0.5 <0.5 - <br /> 5/7/1997 260 5.8 <0.5 <0.5 <0.5 - <br /> 7/22/1997 970 360 <(1.5 <0.5 <0.5 <5.0 <br /> 11/20/1997 140,00(1 16,000 15,000 2,000 13,000 8,700 <br /> 12/16/1997 150,000 20,000 1 16,000 2,300 15,000 14,000 <br /> • While the County has asserted that the presence of 1,2 DCA resulted from an <br /> unauthorized release that occurred at the site,this does not constitute adequate <br /> evidence of responsibility. In fact, 76 percent of the wells also show an increase <br /> in 1,2 DCA of at least 100 percent at some point during the course of monitoring. <br /> One well which indicated the presence of less than 100 parts per billion of 1,2 <br /> DCA in the year 2000,now shows the presence of 1,200 parts per billion. It is <br /> illogical to conclude that such dramatic increases can be attributed to an <br /> underground storage tank that had been removed 17 years before monitoring <br /> began. <br /> The chart below shows another visual illustration of the groundwater degradation since <br /> monitoring and remediation actions began in 1995 (data from Monitoring Well No. 3). <br /> Other wells show a similar trend. <br /> Well UW-3 <br /> eoaoo .. �__-- <br /> �� -TPHg <br /> -Benzene <br /> Toluene <br /> Eth Ibenzane <br /> am a5.000 __ __ Xylenes <br /> Y -MTBE <br /> s 5nuou 1 -Methanol <br /> a zs,aao \ --- <br /> Ethanol <br /> LL 20,000 - <br /> -TBA <br /> ETBA <br /> 5,000 <br /> 0 TAME <br /> Q� Qz Q Q Q Q xx I yz; 1,2 DCA <br /> A . A.. �< $,. � 1 I I ; 3 i �m S" 'E 3 'i' i i EDB _ <br /> ZLL < iLL Q LL < LL LL LL < LL < LL < LL < LL ` LL a LL Q <br />