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WASTE DISCHARGE REQUIREMENTS ORDER R5-2013-0028 -23- DELICATO VINEYARDS, INC. DELICATO FAMILY VINEYARDS SAN JOAQUIN COUNTY Based on the planned modifications to the wastewater management system and expanded LAAs that this Order requires, groundwater quality 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 chloride that prohibits any statistically significant increase in chloride concentrations in any compliance monitoring well and includes a time schedule in the Provisions that requires the Discharger to complete the proposed improvements, evaluate the effectiveness of salinity reduction measures implemented to date, and evaluate the feasibility of additional salinity reduction measures to reduce chloride concentrations in groundwater. This Order also requires that the Discharger evaluate existing and potential future local agricultural uses of groundwater to support determination of a site-specific water quality objective that is protective of all beneficial uses. f. Manganese. The current monitoring program does not require analysis of manganese in wastewater or groundwater. Based on the character of process water supply and nature of typical winery operations, wastewater at the site is not expected to contain significant manganese concentrations. However as noted in Finding 76, excessive BOD loading rates can deplete oxygen, resulting in anoxic conditions that can solubilize naturally occurring metals in soil. A groundwater sample collected from monitoring well MW-2r in August 2012 indicates that the discharge has caused exceedance of the Secondary MCL for manganese. It is possible that the current practice of rapid infiltration with high-BOD wastewater has caused reducing conditions that favor dissolution of manganese from native soil. Additional groundwater monitoring data are needed before a determination of degradation can be made. Based on the planned modifications to the wastewater management system and expanded LAAs that this Order requires, groundwater quality with respect to manganese is expected to improve over time. Therefore, this Order sets a groundwater limitation that prohibits any statistically significant increase in manganese concentrations in any compliance monitoring well; includes a time schedule in the Provisions that requires the Discharger to complete the proposed improvements; and requires monitoring of manganese in the groundwater monitoring wells. If pollution is confirmed by future monitoring data and the required improvements do not result in significantly improved groundwater quality within five years of adoption of this Order, the Provisions require that the Discharger implement additional treatment or control as necessary to bring the discharge into compliance with the Basin Plan water quality objective.