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California Retonal Water Quality Control Board ZZ, k Central Valley Region Robert Schneider,Chair Winston H.Hickox Gray Davis Secretaryfor Sacramento Main Office Governor Environmental Internet Address: http://www.swmb.ca.c.ovhrwgcb5 Protection 3443 Renner Road,Suite A,Sacramento,California 95827-3003 Phone(916)255-3000•FAX(916)255-3015 19 November 2001 Mr. Robert Garcia Leprino Foods, Inc. 1830 West 38th Avenue Denver, CO 80217 SECOND AND THIRD QUARTER 2001 SEMIANNUAL GROUNDWATER MONITORING REPORT,LEPRINO FOODS COMPANY, TRACY,SAN JOAQUIN COUNTY We have reviewed the Second and Third Quarter 2001 Semiannual Groundwater Monitoring Report, Leprino Foods Company, Tracy, San Joaquin County (Report), prepared by GeoTrans, Inc. for Leprino Foods Company and received 1 November 2001. The Report shows petroleum hydrocarbons levels of free product as diesel and Total Petroleum Hydrocarbon as Diesel (TPH-D) concentrations in groundwater are now decreasing, with two exceptions. The Report also states that free product thickness continues to fluctuate, which is considered normal, due to the corresponding fluctuations in groundwater levels. Slight increases in groundwater TPH-D concentrations occurred during June 2001, in the northwestern property boundary monitoring wells MW-14A (73 µg/L) and MW-5 (61 µg/L), which are adjacent to extraction well RW-4A. The TPH-D concentration increases may be due to several mechanical failures, which caused temporary stoppages of both extraction wells RW-4A and RW-5A between#January and June 2001. The system was last repaired on 3 June 2001. Both MW-14A and MW-5 TPH-D concentrations decreased to <50 gg/L in September 2001. The groundwater TPH-D concentrations rebounded, between June and September 2001, in northern property boundary monitoring wells RW-1 (from 140 µg/L to 310 µg/L) and RW-2 (from 180 µg/L to 230 µg/L.), while the groundwater treatment system was operating. Prior to this Report (March 2001), monitoring well RW-1 contained TPH-D at a concentration of 523 ltg/L, after the groundwater extraction system began experiencing mechanical failures. RW-1, RW-2, and RW-3, initially designed as extraction wells, were turned off and recommissioned as monitoring wells prior to 2001, reportedly to prevent drawing the TPH-D groundwater plume towards the site boundary. The Report concludes that the existing extraction wells RW-4A and RW-5A are now effectively providing hydraulic control and preventing migration of the groundwater contaminant plume. California Environmental Protection Agency 0 Recycled Paper