SITE INFORMATION AND CORRESPONDENCE

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California "gional Water Quality Con"- •91 Board Central Valley Region�U_; , Karl E. Longley,SCD,P.E.,Chair Linda S.Adams 11020 Son Center Drive 4200,Rancho Cordova,Califomia 956706114 Arnold Secretaryfor Schwarzenegg Environmental Phone ww 464- 2 1 • 99 4 4 4j4� Protection http://www.wate� I`_n� `Y�11�L_/ Governor 16 December 2009 0.6c t 8 2009 ENVIRONMENT HEALT1{ Mr. Nathan Crum PER-MR/$ERVICES Valley Pacific Petroleum Services, Inc. 166 Frank West Circle Stockton, CA 95206 SEMI-ANNUAL GROUNDWATER MONITORING REPORT AND BIODEGRADATION PARAMETERS BASELINE STUDY, VALLEY PACIFIC PETROLEUM SERVICES, 930 VICTOR ROAD, LODI, SAN JOAQUIN COUNTY Regional Water Quality Control Board, Central Valley Region (Central Valley Water Board) staff reviewed the 13 November 2009 Semi-Annual Groundwater Monitoring and Sampling Report, Third and Fourth Quarters 2009 (Semi-Annual Report) submitted by Ground Zero Analysis, Inc. (GZA) on behalf of Valley Pacific Petroleum Services, Inc. (Valley Pacific) for the site at 930 Victor Road in Lodi (Site). Monitoring at the Site is conducted pursuant to Monitoring and Reporting Program (MRP) No. R5-2002-0827. Groundwater monitoring was conducted in July and October 2009 for the third and fourth quarters, respectively. Depth to groundwater ranged from about 57 feet below ground surface (bgs) to about 61 feet bgs during the third and fourth quarters. MW-7 was dry. Groundwater flow was south-southeasterly at gradients ranging from about 0.003 feet per foot (ft/ft) to 0.01 ft/ft. The observations and gradient calculations are consistent with historical observations. During July, between 0.17 and 0.58 feet of separate phase hydrocarbon (SPH) was measured in two wells (MW-8 and MW-9R). The SPH was removed using a bailer. A Keck "Spoiler" pneumatic hydrocarbon recovery skimming system was taken out of MW- 8 in March 2008 due to malfunctions that caused it to remove excess groundwater from the well. Valley Pacific personnel now periodically remove SPH manually from the wells when observed. During the fourth quarter, no SPH was measured, but a heavy sheen was observed in MW-8 and MW-9R. The Semi-Annual Report estimates that a grand total of about 1,148 gallons of SPH/water mixture have been removed from Site wells since April 1994. During the third and fourth quarters, maximum concentrations of constituents of concern (COCs) at this Site were observed in MW-6R which typically contains SPH. Maximum COCs included 47,000 micrograms per liter (pg/L) of total petroleum hydrocarbons as gasoline (TPHg) and 5,000 pg/L of TPH diesel (TPHd). Maximum benzene, toluene, ethylbenzene, and xylenes (collectively BTEX) concentrations were 4,700 fag/L, 5,800 pg/L, 1 ,000 pg/L, and 7,800 pg/L respectively. The maximum methyl tertiary butyl ether (MTBE) concentration was 3,800 pg/L. California Environmental Protection Agency ca Recycled Paper