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CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD CENTRAL VALLEY REGION MONITORING AND REPORTING PROGRAM NO. R5-2004-0817 CALIFORNIA WATER CODE SECTION 13267 FOR SOUTH SHORE PARCELS,UNOCAL OPERABLE UNIT UNION OIL COMPANY OF CALIFORNIA STOCKTON, SAN JOAQUIN COUNTY Union Oil Company of California(Discharger) is responsible for the Unocal Operable Unit (OU), which was formed as a result of the breakup of the Stockton Group. The other corporations associated with the former Stockton Group are responsible for the L&M OU and Morton OU. The Discharger is responsible for cleanup of the area from Weber Street south to the former Main Street and from the midline of the former Harrison Street east to Lincoln Street, which is shown on Figure 1. Historically, lumber mills,bulk fuel storage/distribution facilities, and various commercial uses occupied Parcel 2A, which resulted in releases of chemicals to the subsurface. This pollution impaired the beneficial use of this water resource. The Discharger owned and/or operated petroleum storage/distribution facilities on Parcel 2A, which is owned by the Stockton Redevelopment Agency. Groundwater is about 15 feet below ground surface. 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 show the presence of various chemicals, including total petroleum hydrocarbons (TPH) as gasoline, TPH as diesel, TPH as motor oil,benzene, toluene, ethylbenzene, xylenes, metals, volatile organic compounds, and semi- volatile organic compounds, some of which are suspected to have been discharged during the Discharger's past operation. 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. R5-2003-0804, which was issued on 27 January 2003. Prior to construction of any new groundwater monitoring or extraction wells, and prior to destruction of any 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 53 monitoring wells associated with the three OUs. Two of the monitoring wells are either missing or damaged. Eight of the 53 wells are associated with the area owned/operated by the Discharger. 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. Monitoring wells with SPH or visible sheen shall be monitored, at a minimum, for product thickness and depth to water. The volume of extracted groundwater also shall be provided in monitoring reports. Sample collection and analysis shall follow standard EPA protocol.