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• 02 May 2001
<br /> AGE-NC Protect No 95-0142 M
<br /> I _ J
<br /> Page 3 of 4
<br />' at,an average hydraulic gradient of 0 01 feet/feet The relative elevation of the ground water surface
<br /> at the site 1s illustrated on Figure 3 ,
<br /> 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES
<br />'I TPH-g was detected in samples collected from wells MW-6, VW-1, VW-2 and VW-3 at
<br /> concentrations of 5,400 micrograms per liter (/ug/1), 170,000,ug/l, 170 4g11 and 6,900 ,ug/l,
<br /> respectively Benzene was reported in samples collected from wells MW-6 and VW-1, VW-2, VW- a
<br />' 3, and VW-4 at concentrations of 16 4g1l, 25,000 4g/1, 1 4,ug/l, 790,ug/l and 0 74/,tg/l, respectively _ <
<br /> Toluene, ethylbenzene and xylenes were also detected in these same samples at concentrations as
<br /> high as 37,000 µg/l (toluene in VW-1)
<br /> MTBE was detected 1n wells MW-5, MW-7 and VW-1 through VW-4 at concentrations of 3 9 ,ug/l, r
<br /> 7 7,ug/l, 720,ccgd, 13 1,4g/1, 130,ug/l, and 9 4,ug/l, respectively MTBE was the only oxygenated fuel
<br /> additive detected in the ground water samples this quarter
<br /> . The analytical results are summarized on Tables 2 and 3 The laboratory report(MAI Laboratory
<br /> I D Nos 60047 through 60055), quality assurance and quality control(QA/QC)report and chain-of-
<br /> custody form are included in Appendix B
<br /> 4.0. CONCLUSIONS _
<br /> Based upon data collected from the site during the current and preceding ground water monitonng
<br /> ' events, AGE,concludes
<br /> • Ground water flow direction.appeared to be toward the northwest in the area defined by the
<br /> shallow-screened well network on-site a.nd,toward the northwest on-site and towards the'
<br /> south off-site in the area defined by the deeper screened well network
<br /> • The highest concentration of dissolved petroleum hydrocarbons continues to be in the area
<br /> the former location of TK1-90 UST TPH-g and'BTEX were not reported in samples
<br /> collected from wells MW-4 and MW-5 which are located in cross-gradient directions from
<br /> the former TK1-90 However, low concentrations of MTBE have been reported in MW-5 '
<br /> rLow concentration BTEX compounds and MTBE were reported in samples collected from
<br /> vapor well VW-4,,which is located in the current down-gradient direction from the former
<br />' location of TK1-90 UST, the known highest concentration of dissolved petroleum
<br /> hydrocarbons
<br /> • Significant,concentrations of TPH-g and benzene were reported in samples from the deeper
<br /> screened well MW-6 (screened 70 to 80 feet bsg) Presently, MW-6 is screened
<br />
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