SITE INFORMATION AND CORRESPONDENCE

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r L� CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD CENTRAL VALLEY REGION MONITORING AND REPORTING PROGRAM NO. R5-2004-0840 FOR DIAMOND WALNUT GROWERS INC. dba DIAMOND OF CALIFORNIA 1050 SOUTH DIAMOND STREET, STOCKTON SAN JOAQUIN COUNTY Diamond Walnut Growers Inc. (Discharger) owns and operates the facility at 1050 South Diamond Street, Stockton in San Joaquin County(site). This site is about 20 acres and shares its northern border with the Union Pacific Railroad Company's right-of-way. The walnut processing operations onsite include storing, cleaning, sorting, refrigerating and milling. The Discharger also operates a 4.5 megawatt co-generation plant that burns walnut shells and pretreats its process wastewater prior to disposal to the City of Stockton sewer. An on-site cooling tower that is part of the refrigeration system previously used anti-scaling solutions that contained chromium. Soil and groundwater, which vanes between about 45 and 55 feet below ground surface, is polluted with total and hexavalent chromium, which impaired the beneficial use of this water resource and threatens the use of public supply well WP-1. This Monitoring and Reporting Program (MRP) is issued pursuant to Section 13267 of the California Water Code and is necessary to delineate groundwater pollutant plumes and determine whether remediation efforts are effective. Existing data and information about the site shows the presence of various chemicals, including total and hexavalent chromium and tetrachloroethene, emanating from the property under the control of the Discharger. The Discharger shall not implement any changes to this MRP unless and until a revised MRP is issued by the Executive Officer. This MRP replaces the requirements listed in MRP No. R5-2002-0821, which was issued on 3 July 2002. Prior to construction of any new groundwater monitoring or extraction wells, and prior to the destruction of any groundwater monitoring or extraction wells, the Discharger shall submit plans and specifications to the Regional 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 9 monitoring wells (MW), 1 facility well (FW) and 4 city supply wells (WP). The FW is used for process water supply and is scheduled to be destroyed. The groundwater monitoring program for the 9 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.