SITE INFORMATION AND CORRESPONDENCE

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Trimark - 2 - 22 July 2004 , ChevronTexaco Mountain House Creek Project to 18 dewatering wells within the construction area to lower the water table. Initially, 10 dewatering wells were installed for the first construction phase and the final wells will subsequently be installed as the excavation progresses north. Soil and/or groundwater at the project site have been impacted by historical leaks from crude oil/bunker C fuel oil pipelines in the area. ChevronTexaco has installed a filtering/granular activated carbon (GAC) treatment system south of Byron Road for treatment of all extracted groundwater. The treatment system has been designed for the removal of petroleum hydrocarbons from the groundwater. The treatment is accomplished initially by a series of Baker settling/separation tanks, skimmers and absorbent pads, and sediment filtration cartridge bag filters. The pretreated groundwater is then pumped through a series of GAC filters to remove any remaining petroleum hydrocarbon compounds. Suspended solids removed by filtering or settlement will be disposed in accordance with Section D of the Order. A diagram of the treatment system, the dewatering wells and the land discharge point are depicted on the attached Figures 2 and 3. Treated groundwater from the treatment system will be pumped approximately 4,000 feet southwest and discharged to Field G. Preliminary pilot studies of the treatment process, including influent and effluent water sampling and analyses, are being conducted to finalize the design and evaluate the effectiveness of the extraction and treatment system. Preliminary review of the effluent analyses for total petroleum hydrocarbons as diesel (TPH-d), benzene, toluene, ethylbenzene, and xylenes (BTEX), naphthalene, and polyaromatic hydrocarbons (PAHs) were non-detect at the respective method detection limits. The Order includes a Monitoring and Reporting Program (MRP) that prescribes wastewater monitoring requirements to evaluate compliance with the effluent discharge limitations contained in the Order. The MRP includes requirements for the sampling and analytical testing for specific petroleum hydrocarbon constituents of both influent and effluent sources. Groundwater extraction, treatment, and monitoring will continue for approximately eight to ten weeks (mid to latter September 2004) after the treatment system begins continuous operation. Seasonally, depth to shallow groundwater along Byron Road ranges between 6 and 17 feet below ground surface and generally flows north-northeast. Shallow groundwater in the area is of poor quality and prohibited for use as domestic or municipal supply in the city of Tracy for administrative reasons unrelated to the presence of degraded crude oillbunker C fuel oil. Applicable City of Tracy Municipal Code prohibits installation of water supply wells in the upper 50 feet of the aquifer. Recent sampling (April 2004) and analysis of shallow groundwater along the pipeline route by Regional Board staff indicates concentrations of total dissolved solids (TDS) of 1,100 to 1,200 mg/L, boron—4.8 to 5.5 mg/L, nitrate (NO3)—25 to 49 mg/L, chloride - 220 mg/L, sodium— 360 to 430 mg/L, potassium— 11 to 22 mg/L, sulfate—ND to 190 mg/L, and hardness (as CaCO3) 420 to 940 mg/L.