SITE INFORMATION AND CORRESPONDENCE

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Public Notification--Generaorder No. R5-2003-0044 Mountain House Creek Restoration Project, Mountain House, California July 6,2004 The groundwater will be treated for disposal using two GAC treatment trains connected in parallel. The combined treatment train will consist of four skid-mounted Calgon Dual Module Carbon Adsorption System (four 20,000-pound vessels)and two skid-mounted Calgon Model 7.5 Adsorption Systems (two 8,000-pound carbon vessels per skid). Each side of the treatment train will consist of 56,000 pounds (112,000 pounds total) of GAC connected in series. Calgon will provide pH stabilized reactivated GAC for the vessels. Sampling ports and pressure indicators are located upstream and downstream of the GAC treatment trains. Pressure indicator readings will be used to determine if the system is operating within range of the manufacturer's specifications. The Model 7.5 carbon vessels are inter- connected by a butterfly valve that can be opened and closed for parallel or in-series operation as site and system conditions change. The contaminant of concern is crude oil and its constituents, which include total petroleum hydrocarbons as diesel (TPHd); benzene, toluene, ethylbenzene,and total xylenes(BTEX); and polynuclear aromatic hydrocarbons(PAHs). These constituents have been detected in groundwater at this site. The treatment system will be located at Assessor Parcel No. 209-040-17; Latitude 37° 47.000' North; Longitude 121` 32.000' West. The system will be operated approximately 250 feet from the area of excavation. The approximate location of the treatment system and dewatering wells are shown on Figure 2. The area of discharge (Field G) is located on Assessor Parcel No. 209- 040-16; Latitude 37'47.000' North; Longitude 121° 33- 000' West. The area of discharge is shown on Figure 3. To discharge petroleum-affected groundwater to land, the California Regional Water Quality Control Board requires that a Report of Waste Discharge (Form 200) and supplemental information(Attachment A) be prepared prior to a proposed discharge. Form 200 and Attachment A for the proposed discharge of extracted groundwater from the Mountain House Creek Project were submitted to the Regional Water Quality Control Board—Central Valley Region dated June 4, 2004. Attachment A includes descriptions of wastewater treatment system and characteristics, site hydrology, groundwater monitoring program, antidegradation analysis, public notice requirements,and associated fees. The proposed improvements at Mountain House Creek will require significant dewatering from an area that has known petroleum impacts. The extracted groundwater will be discharged to land following treatment as described above and in Attachment A. Construction dewatering is tentatively scheduled for early July. Once dewatering begins, it will be performed 24 hours a day, 7 days a week. Dewatering is likely to start by mid to late July. The dewatering and treatment of groundwater is expected to last 8 to 10 weeks. The permit discharge limits as stated in the Order, page 7, Section C: The discharge of an effluent to land for disposal of ground and/or surface water from the cleanup of petroleum pollution must comply with the following limitations: