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Pacific Gas and
<br /> Electric Comp y
<br /> 1 Technical and Ecdlogiial Seiv�ce5 �3a-malmItCanvon Road
<br /> rj'�r_
<br /> rf 'San Ramon,CA 94583
<br /> 00 JUL 31 PM ..25123.2000
<br /> July 26,2000 f7 [ 3
<br /> Ms. Mary Serra
<br /> California Regional Water Quality Control Board
<br /> Central Valley Region
<br /> 3443 Routier Road, Suite A
<br /> Sacramento,CA 95827-3003
<br /> Re: Second Quarter 2000 Groundwater Monitoring Report
<br /> Pacific Gas and Electric Company's
<br /> McMullin Gas Dehydrator Station,Manteca, CA
<br /> Dear Ms. Serra:
<br /> Enclosed is the Second Quarter 2000 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 2000:
<br /> • TPH-gas, TPH-diesel, and BTEX were not detected in the samples collected from well MW-1,MW-3,
<br /> MW-4, and PZ-1.
<br /> • Gasoline-range hydrocarbons were detected in the sample collected from well MW-2 at a'concentration
<br /> of 2,200 micrograms per liter(gg/L).
<br /> • Unknown gasoline-range hydrocarbons were detected in the samples collected from wells MW-5,
<br /> MW-6,MW-7,and MW-8 at concentrations of 280 gg/L, 1,300 gg/L, 480 gg/L, and 54 gg/L(<50
<br /> gg/L dup.), respectively.
<br /> • Early diesel-range hydrocarbons were detected in the samples collected from wells MW-2,MW-5,MW-6,
<br /> and PZ-4 at concer_trations of 6,600 gg/L, 1,900 gg/L, 260 gg/L, and 340 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 16 gg/L, 3.2 gg/L, 6.9 gg/L,and 20 gg/L,respectively.
<br /> Toluene was detected in the sample collected from well MW-2 at a concentration of 3.1 gg/L.
<br /> • Ethylbenzene was detected in the samples collected from wells MW-2,MW-6, and MW-7 at
<br /> concentrations of 89 gg/L, 22 gg/L,and 3.4 gg/L, respectively.
<br /> • Total xylenes were detected in the samples collected from wells MW-2, MW-6, and MW-7 at
<br /> concentrations of 160 gg/L, 34 gg/L, and 5.3 gg/L,respectively.
<br /> • Lead was not detected in any of the groundwater samples.
<br /> • The direction of groundwater flow was to the west-southwest, with a hydraulic gradient of approximately
<br /> 0.001 foot per foot.
<br /> 402 331-00 168.doc
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