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' FIRST QUARTER 2006 GROUNDWATER TREATMENT FACILITY MONITORING REPORT FORWARD LANDFILL WDR ORDER NO.R5-2003-0080 removed approximately 2.4 pounds of VOCs.Table 1 presents the monthly average effluent flow rates in gallons per day(gpd). TABLE 1 Monthly Average Effluent Flow Rates Forward Landfill Groundwater Treatment Fac##Monitoring Report,First Quarter 2006 Average Flow Rate Month (gpd) January 119,000 ' February 120,000 March 119,000 At the beginning of first quarter 2006,only extraction well (EW)-1 was operational,and effluent was discharging to the infiltration pond. EW-2 was turned on in manual mode on December 29,2005,and operated for approximately 1 hour. After an elevated water level was observed in the air stripper sump, EW-2 was turned off. The air stripper sump was inspected on January 18,2006,and a significant buildup of mineral scale was observed at the base of the sump and around the siphon tube.The buildup appeared to limit the flow of ' water out of the sump. The GTF was shut down on March 13,2006,and the air stripper packing material and sump were acid washed between March 14 and 16,2006.This routine maintenance procedure removes mineral deposits, thereby improving the efficiency of the treatment system.The packing and sump were inspected on March 15,2006, and found to be free of scale. The effluent from the acid wash was neutralized,buffered,and stored in a holding tank onsite. Sampling and analysis of the acid-wash effluent are being conducted to meet the require- ments of the City of Stockton Regional Wastewater Control Facility. The acid-wash effluent will be disposed of during second quarter 2006. On March 17,2006, the GTF was restarted at 12:09 p.m. with extraction wells EW-1 on and EW-2 off. The plant operated normally in this configuration for over 1 hour. EW-2 was restarted in manual mode at 1:15 p.m. on March 17,2006. A field technician then drove to the air stripper to observe the water level in the air stripper sump. At 1:22 p.m., the technician observed that groundwater had filled the sump and shut off the blower and EW-1. The technician shut off EW-2 at 1:28 p.m.The high water level in the sump and the shutdown of the blower might have resulted from a partial blockage in the GTF effluent pipeline. It is estimated that on March 17,2006,2,000 gallons of groundwater extracted from EW-1 and EW-2 were discharged to the infiltration pond while the GTF blower was off.The total volume includes approximately 1,900 gallons from EW-1 and 100 gallons from EW-2. Based on the most recent analytical results for groundwater extracted from EW-1 and EW-2,the estimated maximum total VOC mass discharged to the infiltration pond is 0.00052 pound. It is likely that some of this mass volatilized to the atmosphere before it reached the pond.The extracted groundwater would have contacted air as it trickled through the air stripper packing,at the effluent pipe outfall,and as it was conveyed 330 feet in the effluent channel to the infiltration pond.The CVRWQCB was informed of the release via telephone on March 17, 2006, and via e-mail on March 20,2006. RDDI061100003(NLH3129.DOC) 2