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CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD <br /> CENTRAL VALLEY REGION <br /> MONITORING AND REPORTING PROGRAM NO. 96- F T <br /> FOR <br /> POST CLOSURE MAINTENANCE AND MONITORING <br /> UNOCAL CORPORATION AND WESTERN FARM SERVICE, INC. <br /> RETAIL FERTILIZER FACILITY, STOCKTON <br /> SAN JOAQUIN COUNTY <br /> From the early 1950's to 1992, the Unocal Corporation, through its subsidiary PureGro Company, <br /> operated a retail fertilizer facility at 1905 N. Broadway Avenue in Stockton. The facility was sold <br /> to Crop Production Services in 1992; however, as part of the sale agreement, Unocal retained the <br /> responsibility for addressing the environmental issues which developed as a result of its operations. <br /> Crop Production Services was recently acquired by Western Farm Service, Inc. <br /> In October 1996, two former onsite evaporation ponds were capped through the installation of a <br /> geosynthetic composite liner, followed by 3" of sand, 9" of aggregate baserock, and finally 4" of <br /> asphaltic concrete. Two permanent monuments were installed in each pond area so that the location <br /> of the wastes could be determined throughout the post-closure maintenance period. <br /> This Order requires Unocal Corporation to perform post-closure maintenance and monitoring on two <br /> former evaporation ponds. Western Farm Service, Inc. (the landowner and current operator) will be <br /> required to perform the maintenance and monitoring only in the event that Unocal Corporation fails <br /> to comply with this Order. <br /> GROUNDWATER MONITORING <br /> There are nine monitoring wells at the site, as shown on Attachment A. The groundwater <br /> monitoring program for these wells, and any additional wells installed after the date of this Order, <br /> shall include the constituents listed below. The method of sample collection and analysis shall <br /> follow EPA's standard methods. <br /> Type of Sampling <br /> Constituents Units Sample Frequency <br /> Depth to ground water 0.01 feet Quarterly' <br /> Nitrate-N mg/1 Grab Semiannually' <br /> Total Kjeldahl nitrogen mg/l Grab Semiannually' <br /> Volatile organics (EPA 601 or 8010) µg/I Grab Semiannually' <br /> Chlorinated herbicides (EPA 615) µg/1 Grab Semiannually' <br /> Electrical conductivity µmho/cm Grab Semiannually' <br /> pH pH units Grab Semiannually' <br /> `March, June, September, and December <br /> 'March and September <br />