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WASTE DISCHARGE REQUIREMENTS ORDER R5-2013-0028 -20- DELICATO VINEYARDS, INC. DELICATO FAMILY VINEYARDS SAN JOAQUIN COUNTY Background Downgradient Objective Effluent Groundwater Groundwater m /L TDS 1,442 169-777 1,663 450 4 to 1,500$ FDS 706 -- -- -- Nitrate as Nitrogen 1.4 6.8-32 1.0 106 TKN 5 32 1.2- 1.3 0.86 -- Sulfate 154 8.0-97 163 2507 Sodium -- 8.7-86 366 694 Chloride -- 2.4 -23 123 106 4-600$ Manganese 8 -- <0.005—0.009 0.0175 0.0507 Iron 8 -- <0.05 <0.05 0.300 7 Arsenic 8 -- 0.005—0.022 0.007 0.0106 Flow weighted average from 2002-2011. 2 Compiled from MW-4, MW-5, and MW-6 data collected from 2008-2012. 3 Compiled from MW-3; mean of data collected 2001-2012. 4 Lowest agricultural water quality goal. 5 Total Kjeldahl nitrogen. 6 Primary Maximum Contaminant Level. Secondary Maximum Contaminant Level. 8 Secondary Maximum Contaminant Level range. 9 Based on a single groundwater sampling event conducted in August 2012. a. Total Dissolved Solids. The average wastewater FDS and TDS concentrations are 706 and 1,442 mg/L, respectively. The average TDS concentrations in background monitoring wells MW-4, MW-5, and MW-6 show that background groundwater quality is spatially variable with respect to TDS and has likely been degraded by agricultural land use upgradient of the site. As noted in Finding 61, the 95% upper confidence limit on the mean background TDS concentration is 724 mg/L. TDS concentrations in monitoring wells MW-2 and MW-3, which are downgradient of current LAAs, average 1,663 mg/L. Therefore, the previous and current discharge has caused exceedance of the least stringent potential water quality objective for protection of MUN beneficial uses, which is the short-term maximum secondary MCL of 1,500 mg/L. There is not sufficient information about local agricultural practices to interpret the narrative water quality objective for protection of AGR beneficial uses. Therefore, this Order requires that the Discharger submit the information required to make this determination. Based on the planned modifications to the wastewater management system and expanded LAAs that this Order requires, groundwater quality with respect to TDS is expected to improve over time, but it is not possible to predict the level of improvement that can achieved or when it might occur. Therefore, this Order sets a groundwater limitation for TDS that prohibits any statistically significant increase in groundwater TDS and includes a time schedule in the Provisions that requires the Discharger to complete the proposed improvements, and evaluate the effectiveness of salinity reduction measures