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Revised Site Characterization Work Plan SMH Mountain House,LLC Page 2 2.0 DESCRIPTION OF FACILITIES AND DISCHARGES A location map and site map are included in Figure 1, Vicinity Map. The permitted facilities that SMH will decommission include reclamation areas and three effluent storage reservoirs shown on Figure 2, Monitoring Sites. Facility descriptions, permits, and monitoring history were described in detail in submittals 2 and 5. Reservoir IA has a bottom liner of compacted soil with flexible membrane liner (FML) covering the embankments (submittal 2). Reservoir 113 and Reservoir 2 are fully lined with a single 60-mil FML. Reservoir 2 never stored any effluent nor was placed into service for any use. Reservoirs IA and 1B were last used in 2007, when effluent was discharged to Reclamation Area 1 (submittal 5). The reservoirs do not contain sludge (submittal 2). Solid materials above the liners consist of wind-blown soil and vegetative debris, or previously-bagged soil imported as liner ballast during construction. All reservoirs had evaporated dry by summer of 2008, and any water contained in the reservoirs is stormwater from precipitation on the reservoir footprints. 3.0 RECLAMATION AREA CLOSURE—NO SAMPLING PROPOSED Only Reclamation Area 1 was used for discharge of treated effluent, no wastewater was discharged to Reclamation Areas 2 and 3 (submittal 5). Land application to Reclamation Area 1 was conducted during 2005, 2006, and 2007 and constituted a fallow ground discharge. Monitoring of Reclamation Area 1 was performed under the Monitoring and Reporting Program (MRP) for Order No. 98-109. The nitrogen application rate was so far below standard crop nitrogen requirements that the potential impact to groundwater as a result of the practice was negligible. Results of monitoring programs demonstrate that past discharges of reclaimed wastewater to Reclamation Area 1 has not caused degradation of groundwater quality (submittal 5). Annual soil sample tests included 10 metals, total nitrogen, electrical conductivity and pH. All soil data is included in Attachment 2. There were a total of 72 sample results from Reclamation Area 1 and 35 samples from Reclamation Areas 2 and 3, which compose a background population. The most recent soil samples were taken from Reclamation Area 1 in April 2007. This single sampling event at 12 locations comprises a final sample set. Except for molybdenum, the maximum value for each parameter from this sample set was below the maximum value of the respective parameters in the background data set. The maximum molybdenum value of 3.1 mg/kg is well below the following levels considered threatening for groundwater degradation or human health. 1. Environmental Screening Level (2007) from the San Francisco Bay Region Water Quality Control Board of 40 mg/kg. 2. The California Human Health Screening Level (CHHSL)of 380 mg/kg. 3. EPA Regional Screening Level for Health Hazard(ingestion)of 390 mg/kg. 4. Total Threshold Limit Concentration(TTLC)of 3,500 mg/kg. Based on this analysis we conclude there is no increased risk of groundwater contamination as a result of past discharges to Reclamation Area 1. We propose no confirmation soil samples for the Reclamation Areas. These areas will be decommissioned without further evaluation. lkk�� �' CO