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<br /> Pacific Gas and
<br /> & Electric Company
<br /> Technical and Ecological Services 3400 Crow Canyon Road
<br /> San Ramon,CA 94583
<br /> 925.820.2009
<br /> March 21,2000
<br /> Ms. Mary Serra2��`I�q�Z
<br /> California Regional Water Quality Control Board 0
<br /> Central Valley Region `q 0
<br /> 3443 Routier Road, Suite A APR 14 2000
<br /> Sacramento,CA 95827-3003
<br /> ENV1RCNN')Ei\1-'fA. HEALTH
<br /> Re: Fourth Quarter 1999 Groundwater Monitoring Report PERMIT/SERVICES
<br /> PG&E's McMullin Gas Dehydrator Station,Manteca, CA
<br /> Dear Ms. Serra:
<br /> Enclosed is the Fourth Quarter 1999 Groundwater Monitoring Report for PG&E's McMullin Gas Dehydrator
<br /> Station. In August 1998, a compound formulated by Regenesis®called Oxygen Releasing Compound(or
<br /> 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 November 1999:
<br /> • TPH-gas,TPH-diesel, and BTEX were not detected in the samples collected from well MW-1, MW-3,
<br /> MW-4,and MW-8.
<br /> • TPH-gas was detected in the samples collected from wells MW-2, MW-5,MW-6, and MW-7 at
<br /> concentrations of 38,000 micrograms per liter(gg/L), 940 gg/L, 7,600 gg/L,and 6,400 gg/L,
<br /> respectively.
<br /> • Hydrocarbons in the early diesel range were detected in the samples collected from wells MW-2, MW-5,
<br /> MW-6, and MW-7 at concentrations of 5,500 gg/L, 1,200 gg/L, 3,900 gg/L, and 3,500 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 1,300 gg/L, 28 gg/L, 380 gg/L, and 400 µg/L,respectively. 1
<br /> • Toluene was detected in the samples collected from well MW-2, MW-6, and MW-7 at concentrations
<br /> of 430 �L, 47 gg/L, 49 gam , res respectively.
<br /> • Ethylbenzene was detected in the samples collected from wells MW-2, MW-5,MW-6, and MW-7 at
<br /> concentrations of 4,900 gg/L, 5.7 gg/L, 880 gg/L, and 520 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 5,600 gg/L, 15 gg/L, 620 gg/L, and 970 gg/L, respectively.
<br /> • The direction of groundwater flow was to the southwest,with a hydraulic gradient of approximately
<br /> 0.003 foot per foot.
<br /> 402.331-00.62.61
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