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California Ogional Water Quality Cool Board <br /> l\- Central Valley Region ' <br /> v Katherine Hart, Chair <br /> Linda S. Adams rnold <br /> Secretary for 1685 E Street, Fresno,California 93706 enegger <br /> Environmental (559)445-5116 • Fax(559)445-5910 �tC�� emor <br /> Protection http://www.waterboards.ca.gov/centralvalley l`� <br /> 20 July 2010 !l�1. ; 1010 <br /> ENIRERMI SERVICES <br /> Lee Higgins <br /> Chevron Environmental Management Company <br /> 6111 Bollinger Canyon Road <br /> BR 1 Y/3484 <br /> San Ramon, CA 94583 <br /> REVIEW— 2010 ANNUAL GROUNDWATER MONITORING AND SAMPLING REPORT, <br /> ALDEN PARK, TRACY, SAN JOAQUIN COUNTY <br /> Chevron Environmental Management Company (Chevron) submitted the Annual 2010 <br /> Groundwater Monitoring and Sampling Report (Report) dated 19 April 2010, for the Alden <br /> Park site (Site) in Tracy. The Report was prepared for Chevron by Science Applications <br /> International Corporation (SAIC) and submitted to Central Valley Regional Water Quality <br /> Control Board (Central Valley Water Board) staff for review. <br /> Groundwater sampling and monitoring was conducted in accordance with Monitoring and <br /> Reporting Program (MRP) R5-2006-0812. The Report provides an annual summary of the <br /> 2010 groundwater monitoring analytical results for the 17 wells associated with the former Old <br /> Valley Pipeline fuel oil reservoir site, now occupied by the City of Tracy's Alden Park. Field <br /> activities were conducted in January 2010. <br /> According to SAIC's Report: <br /> • Eight of the wells were purged and sampled. The remaining nine contained free <br /> product. Free product thickness was measured and recorded prior to removal. <br /> • Depth to water ranged between 11 and 15 feet below ground surface with a north- <br /> northwest gradient, which is consistent with prior information. <br /> • Total petroleum hydrocarbons as diesel (TPHd) at 410 micrograms per liter (pg/L) was <br /> reported in a sample from downgradient monitoring well (MW)-7, and in samples from <br /> 77 to 93 pg/L in three crossgradient wells. Analytical results of samples from the four <br /> remaining wells were non-detect (ND) for TPHd, consistent with previous results. <br /> • Low concentrations of five polynuclear aromatic hydrocarbons (PAHs) at or slightly <br /> above the method detection limits were detected in the MW-8 sample, also consistent <br /> with prior results. PAHs were ND in the remaining samples. <br /> • Absorbent socks used in MW-5 and MW-21 for removal of TPH sheen are monitored <br /> quarterly and replaced as necessary. A replacement sock was installed in MW-5. <br /> California Environmental Protection Agency <br /> edRecycled Paper <br />