ARCHIVED REPORTS_RPT OF WASTE DISCHARGE FOR WASTEWATER DISPERSAL 2011

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Diamond Pet Food Processors of Ripon,LLC June 30,2011 Report of Waste Discharge Page 11 of 17 Between June 26 and August 16, 2007, approximately 135.6 acre feet(44 million gallons) of low (133 mg/L) TDS water were pumped into Diamond's east percolation field and allowed to infiltrate into the subsurface. The east percolation field is located between a high TDS plume originating from the bottom of ASB-2 and production wells PW-6 through PW-8. In addition to recharging the semiperched aquifer with low TDS water, the irrigation water had the additional benefit of creating a hydrologic barrier between ASB-2's TDS plume and the production wells. Improving the quality of water in the vicinity of the production wells ultimately improves the quality of water discharged by the mill as effluent. Groundwater quality improved in the immediate vicinity of the east percolation field in the semiperched,upper, and intermediate aquifers following the application of SSJID water.13 The third season of applying low TDS water to the east percolation field began on August 3, 2009, and ended on September 23, 2009. A total of 21.77 acre feet(7.1 million gallons) of water from production well PW-6 were placed on Diamond's east percolation field. During 2010, low TDS water was not applied to the east percolation field, although all process water that was applied around the remainder of the site contained TDS concentrations below the 713 mg/L WQPS established for the semiperched aquifer(Figure 5). Groundwater quality has continued to improve across the southeast and central portions of the Diamond site as the result of(1) recharging the semiperched aquifer underlying the east percolation field with low TDS surface water during the irrigation seasons of 2007 and 2008 and with low TDS groundwater during the 2009 irrigation season; and (2) discontinuing paper production at the mill that has reduced TDS loading to the semiperched aquifer by 3,676 pounds per day based on average 2008 mill production. Groundwater with TDS levels higher than the WQPS is encroaching in the southwest quadrant of the Diamond site, as recharge from the City of Ripon's MWWTF moves easterly towards the Diamond site. POTENTIAL IMPAIRMENT TO GROUND AND SURFACE WATER(§21750(A)) The discharge potentially could impair water quality through(1) direct flow to surface waters if the irrigation areas overflowed to the Stanislaus River or(2)percolation of the wastewater through the irrigated fields into the subsurface. 13 L&A,February 8,2008, Combined 2007 Annual Summary Report, 4th-Quarter 2007 Groundwater-Monitoring Report, And Preliminary Corrective Action Evaluation,Neenah Paper Company,Ripon, California. 010107.00, Task I Lawrence&Associates w:Iclientsl diamond pet foods1010107.00-ripon rowdldiamondpet_rowdjune2011_draft.docx