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0 • <br /> California Regional Water Quality Control Board <br /> Central Valley Region <br /> Robert Schneider,Chair <br /> Terry Tamminen Fresno Office <br /> 1685 E Street,Fresno,California 93706-2020 Arnold Schwarzenegger <br /> Secretaryf'or Phone(559)445-5116•FAX(559)445-5910 Governor <br /> Environmental Internet Address: http://www.swrcb.ca.gov/—mgcb5 <br /> Protection <br /> 20 November 2003 <br /> Mr. M. Scott Mansholt <br /> Chevron Environmental Management Company <br /> Property Management <br /> 6001 Bollinger Canyon Road <br /> P. O. Box 6012 <br /> San Ramon, CA 94583-0712 <br /> SECOND SEMIANNUAL 2003 GROUNDWATER MONITORING REPORT (JULY— <br /> DECEMBER), ALDEN PARK, TRACY, SAN JOAQUIN COUNTY <br /> We have reviewed the Second Semiannual 2003 Groundwater Monitoring Report(July -December), <br /> Alden Park, Tracy, San Joaquin County (report), dated 27 October 2003, prepared for Chevron <br /> Environmental Management Company by Science Applications International Corporation (SAIC). The <br /> monitoring was conducted in accordance with Monitoring and Reporting Program R5-2003-0801. The <br /> report provides the 26 and 27 August, and 9 September 2003 groundwater monitoring analytical results <br /> for the former Old Valley Pipeline fuel oil reservoir site now occupied by Alden Park in Tracy, CA. <br /> There are 21 monitoring wells associated with this project; twelve of the wells were purged and sampled, <br /> eight wells contained free product (for the first time, a sheen was observed in MW-21), and one well was <br /> dry. Concentrations of total petroleum hydrocarbons as diesel (TPH-d) at 15,000 µg/L and 600 gg/L <br /> (w/o silica gel cleanup), was reported in MW-5 and MW-7, respectively, downgradient (north) of the <br /> former reservoir. With the exception of the results noted above, TPH-d was not detected in the <br /> remaining monitoring wells; and polynuclear aromatic hydrocarbon compounds (PAHs) were not <br /> detected in any of the monitoring wells this event. <br /> During this event, floating product thickness ranged from a sheen to a maximum of 1.92 feet in MW-15. <br /> Approximately 5 gallons of floating product was removed this quarter. Since product removal was <br /> initiated in April 1997, over 355 gallons have been removed from the monitoring wells containing <br /> product. <br /> SAIC has proposed eight wells for destruction (MWs 1, 2, 4, 9, 11, 13, 14, and 17); their justification is <br /> that the wells are "redundant" and not needed for monitoring. Review of historical results indicates <br /> these wells have been consistently non-detect or very low PAHs, TPH-d, and/or less than water quality <br /> objectives since sampling commenced in 1997. One upgradeint well has been dry on different occasions, <br /> four of the wells are cross/up-gradient, and three are cross/down-gradient (MW-1 is 500 feet NW of <br /> MW-10, which is 400-feet NW of the project area). If the eight wells were destroyed as proposed, this <br /> California Environmental Protection Agency <br /> ov <br /> ea Re, 1"d Pap,) <br />