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California RAgonal Water Quality Controt Board <br /> Central Valley Region <br /> Linda S.Adams Arnold <br /> Secretaryfor Schwarzenegger <br /> Environmental Fresno Branch Office Governor <br /> Protection 1685 E Street,Fresno,California 93706 <br /> (559)445-5116•Fax(559)445-5910 <br /> http://www,waterboards.ca.gov/centraIvalley <br /> 4 December 2006 <br /> M. Scott Mansholt <br /> Chevron Environmental Management Company <br /> 6001 Bollinger Canyon Road <br /> Rm K2066 <br /> San Ramon, CA 94583-2324 <br /> REVIEW OF SECOND SEMI-ANNUAL AND 2006 ANNUAL GROUNDWATER <br /> MONITORING AND SAMPLING REPORT—ALDEN PARK, TRACY, SAN JOAQUIN <br /> COUNTY <br /> Regional Water Board staff has reviewed the referenced groundwater sampling report, dated <br /> 27 October 2006 prepared for Chevron by Science Applications International Corporation <br /> (SAIC). The Alden Park site and two other nearby Chevron sites (990 Beechnut and TAOC <br /> Tracy Pump Station) were associated with the operation of the former Tidewater Associated <br /> Oil Company (TAOC) Tracy Pump Station; both are separate sites regulated by the Central <br /> Valley Regional Water Quality Control Board, Fresno office. <br /> The former Alden Park project consisted of one 750,000 barrel (31,500,000 gallons) concrete <br /> reservoir for storage and distribution of Bunker C fuel oil used as locomotive fuel. The facility <br /> was removed from service in 1957. After the concrete reservoir was removed, the area was <br /> used for farming throughout the 1960s and subsequently developed to residential by different <br /> developers during the 1970s and 1980s. <br /> Groundwater monitoring and sampling was conducted in early August 2006 in accordance with <br /> Monitoring and Reporting Program (MRP) R5-2003-0801. During the year, with approval by <br /> Regional Water Board staff, five monitoring wells that were no longer needed were properly <br /> destroyed. Sixteen wells remain for monitoring including seven that contain floating product <br /> that is removed on a quarterly basis. Depth to groundwater is between 11 and 14 feet with a <br /> north-northwest gradient of 0.003 ft/ft. <br /> Groundwater samples are submitted for analysis of total petroleum hydrocarbons (TPH) as <br /> diesel (TPHd) and polynuclear aromatic hydrocarbons (PAHs). TPHd was reported in <br /> downgradient well MW-7 at 380 ug/I and non detect (ND) in the remaining seven wells not <br /> containing floating product. Approximately 27-gallons of floating product, ranging in thickness <br /> from approximately one foot to over six feet in MW-16, was removed over the two previous <br /> quarters. Oleophilic absorbent socks are used in two wells, which are checked quarterly and <br /> replaced as needed. Non-detect to low PAH concentrations slightly over reporting levels, were <br /> reported in two wells; the values were below their respective regulatory screening levels. <br /> California Environmental Protection Agency <br /> �d Recycled Paper <br />