SITE INFORMATION AND CORRESPONDENCE

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NOA No.R5-2003-004410 -2- 29 May 2003 Dewatering Discharge City of Tracy, Stormwater Pipeline Project field, lies within Section 24, T2S, R4E, MDB&M. The City's detention basin No. 10 lies within Section 18, T2S, R5E, MDB&M. PROJECT DESCRIPTION The project includes the excavation and installation of two parallel 60-inch diameter pre-cast concrete stormwater pipelines within the same trench beneath Byron Road. However, the pipelines require dewatering to lower the shallow groundwater prior to their placement. The dewatering process involves approximately 130 dewatering wells along the proposed route to lower the shallow water table in order to install the pipelines. Soil and/or groundwater along much of the route have been impacted by historical leaks from two crude oil/bunker C fuel oil pipelines in the area. ChevronTexaco has installed four identical treatment systems along Byron Road for treatment of all groundwater extracted by the dewatering wells. The four treatment systems (Nos. 1-4) at four locations (Nos. 1-4) have been designed for the removal of petroleum hydrocarbons from the groundwater extracted from the Byron Road construction-dewatering wells. The treatment is accomplished initially by a series of Baker settling/separation tanks, skimmers and absorbent pads, sediment filtration cartridge bag filters, and bentonite clay/anthracite filters. The pretreated groundwater is then pumped through a series of granular activated carbon (GAC) filters to remove any remaining petroleum hydrocarbon compounds. A diagram of a typical treatment system, the dewatering wells and the three land discharge points are depicted on the attached Figure. Treated groundwater from Treatment Systems Nos. 1 and 4 will be discharged to the following locations: 1. The City of Tracy's Belconte Drive/stormwater detention basin No. 5, south of the eastern end of the project site (Discharge Point#1); 2. The City of Tracy stormwater detention basin No. 10, approximately one-half mile north of the western end of the project site (Discharge point#5); and, 3. A contingent location for additional capacity is the 50-acre agricultural site (Pombo site), approximately one-quarter mile northwest of the west end of the project site (Discharge Point#4); Treated groundwater will also be sent to the City of Tracy's wastewater treatment plant via the sewer line (Discharge Point Nos. 2 and 3). The discharge to the City's wastewater treatment plant from Treatment Systems Nos. 2 and 3 are not subject to this Order. Preliminary pilot studies of the treatment processes, 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.