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t.
<br /> Pacific Gas and
<br /> L Electric Company
<br /> Technical and Ecological Services 3400 Craw Canyon Road
<br /> San Ramon,CA 94583
<br /> • 925.820.2000
<br /> .rely 23,2001 LE
<br /> Ms. Mary Serra
<br /> JUL 2 6 2001
<br /> California Regional Water Quality Control Board ENVIRONMEN•F HEALTH
<br /> Central Valley Region PERMIT/SERVICES
<br /> 3443 Routier Road, Suite A
<br /> Sacramento, CA 95827-3003
<br /> Re: Second Quarter 2001 Groundwater Monitoring Report
<br /> Pacific Gas and Electric Company's McMullin Gas Dehydrator Station, Manteca, CA
<br /> Dear Ms. Serra:
<br /> Enclosed is the Second Quarter 2001 Groundwater Monitoring Report for Pacific Gas and Electric Company's
<br /> McMullin Gas Dehydrator Station. In August 1998, a compound formulated by Regenesis®called Oxygen
<br /> Releasing Compound(or ORC)was injected at this site to enhance biodegradation rates in the subsurface.
<br /> The following is a summary of field and laboratory results performed in May 2001: .,;
<br /> • TPH-G,TPH-D,-and BTEX were not detected in the samples collected from wells MW-1, MW-3,MW-4,
<br /> • and PZ-1.
<br /> •
<br /> 'Unknown diesel-range petroleum hydrocarbons were detected in the samples collected from wells
<br /> MW-2,MW-5,MW-6,MW-7,MW-8, and PZ-4 at concentrations of 1600 micrograms per liter(4g/L),
<br /> 310 gg/L, 990 µg/L, 160µg/L, 75 Rg/L, and 82 gg/L,respectively.
<br /> • Unknown gasoline-range petroleum hydrocarbons were detected in the samples collected from wells MW-
<br /> 5 and MW-7 at concentrations of 400 and 270 4g/L,respectively.
<br /> • TPH-G was detected in the samples collected from wells MW-2 and MW-6 at concentrations of 1800
<br /> pg/L and 2000 gg/L,; respectively.
<br /> • Benzene was detected in the samples collected from wells MW-2, MW-5, MW-6, and MW-7 at
<br /> concentrations of 17 p.g/L, 14 µg/L,40 µg/L, and 2.7 gg/L,respectively.
<br /> • Toluene was detected in the sample collected from well MW-6 at a concentration of I 1 gg/L.
<br /> • Ethylbenzene was detected in the samples collected from wells MW-2,MW-6, and MW-7 at
<br /> concentrations of 130 µg/L, 200 µg/L, and 0.6 gg/L,respectively.
<br /> • Total xylenes were detected in the samples collected from wells MW-2,MW-5,MW-6, and MW-7 at
<br /> concentrations of 170 µg/L, 1.4 pg/L,240 4g/L, and 1.4 4g/L,respectively.
<br /> • Methane was detected in the samples collected from wells MW-2,MW-5, MW-6, and PZ-4 at
<br /> concentrations of 0.054 mg/L., 0.056 mg/L, 0.11 mg/L, and 0.014 mg/L,respectively.
<br /> • Lead was not detected in any of the samples collected.
<br /> • • The direction of groundwater flow was to the west,with a hydraulic gradient of approximately 0.003 foot
<br /> per foot.
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