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CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD CENTRAL VALLEY REGION MONITORING AND REPORTING PROGRAM NO. 5-01_XXX FOR UNOCAL CORPORATION AND AGRIUM, INC. STOCKTON, SAN JOAQUIN COUNTY From the early 1950s to 1992, the UNOCAL Corporation, through its subsidiary PureGro Company, operated a retail fertilizer facility at 1905 North Broadway Avenue in Stockton. Two evaporation ponds were used to dispose of fertilizer and pesticide rinsates between approximately 1965 and 1985. The facility was sold to Crop Production Services in 1992, although UNOCAL retained the responsibility for addressing the environmental issues. Crop Production Services is now operated by Western Farm Service, Inc. Both corporations are owned by Agrium, Inc. If UNOCAL fails to comply with this Order, then Agrium will be required to perform the monitoring. In October 1996, the two on-site evaporation ponds were capped with a geosynthetic composite liner, overlain by three inches of sand, nine inches of aggregate baserock, and four inches of asphaltic concrete. Two permanent monuments were installed in each pond area so that the location of the ponds could be determined throughout the post- closure maintenance period. This Monitoring and Reporting Program (MRP) is issued pursuant to Section 13267 of the California Water Code and is designed to delineate groundwater contaminant plumes, determine whether remediation efforts are effective, and maintain the integrity of the former pond caps. The Discharger shall not implement any changes to this MRP unless and until a revised MRP is issued by the Executive Officer. Five of years of monitoring data show it is appropriate to reduce the monitoring frequency and adjust the scope ri monitored constituents. of This MRP replaces the requirements listed in MRP No. 96-816, which was issued on 7 November 1996. Prior to construction of any new groundwater monitoring or extraction wells, the Discharger shall submit plans and specifications to the Board for review and approval. Once installed, all new wells shall be added to the monitoring program and shall be sampled and analyzed according to the schedule below. GROUNDWATER MONITORING As shown on Figure 1, there are 10 monitoring wells: MWs 1-3, MWs 5-10, and MW-12. Two of these wells, MW-5 and MW-7, are not subject to the requirements ofthis MRP. The groundwater monitoring program for the eight monitoring wells and any wells installed subsequent to the issuance of this MRP, shall follow the schedule below. Sample collection and analysis shall follow standard EPA protocol.