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' • • ORDER NO.R5-2002-0148 - 17 - INFORMATION SHEET MUSCO FAMILY OLIVE COMPANY AND THE STUDLEY COMPANY WASTEWATER TREATMENT AND LAND DISPOSAL FACILITY SAN JOAQUIN COUNTY Effluent Limitation C.1 Loading limits for total dissolved solids are needed for several reasons. "Total dissolved solids" consist of both inorganic salts and a volatile component including sugars and carbohydrates. Crops are unable to take up excessive concentrations of inorganic solids such as sodium and chloride, resulting in leaching and groundwater degradation, especially at the loading rate the Discharger had proposed. When wastewater is evenly applied to soil at appropriate rates, the volatile component of TDS is usually biodegraded within the soil profile and removed from the leachate. However, overloading can lead to the presence of BOD, a measure of the volatile component of TDS, in the groundwater. To determine the appropriate concentration limits for the wastewater, staff reviewed the Designated Level Methodology for Waste Classification. Because the discharge is planned to continue indefinitely, the use of an attenuation factor is not appropriate because all the attenuation processes will become saturated over time. Therefore, the effluent limits are set by the background groundwater quality. The Discharger has requested that the salt limitation be expressed as "dissolved inorganic solids" (DIS) instead of"total dissolved solids" (TDS). The Discharger indicates that the effluent limit should only apply to the inorganic portion. However, the effluent limitation is expressed as TDS for several reasons. First, if wastewater is overloaded onto the land application areas, then the volatile component may not be fully degraded and a DIS value may not fully measure the extent of dissolved solids which reach the groundwater. The limited groundwater monitoring conducted to date shows that there is BOD in six of the shallowest monitoring wells, indicating that the groundwater may already be degraded by the volatile portion of TDS. Second, neither the 1-million gallon settling pond nor the 84-million gallon storage pond are constructed to meet Title 27 standards. The waste currently produced by the Discharger is considered designated waste and if not treated to reduce concentrations, would have to be stored in a pond constructed with a double liner and leachate collection system. Although the Discharger states that the native clay underlying the 84 million gallon storage pond can be to compacted to a hydraulic conductivity of approximately 10"6 cm/sec, this does not meet the prescriptive standards nor the performance standards of Title 27 which include a leachate collection system to reduce the hydraulic head and a second liner. If the effluent limit were to be expressed as DIS instead of TDS, then there would be no control over the volatile portion of the waste stored in the pond, and it is expected that the existing elevated BOD in the waste, coupled with the 20-30 feet of hydraulic head in the pond, would cause leaching of the volatile solids and degradation of the shallow (10 feet bgs) groundwater underlying the pond. After the Discharger treats its waste to comply with the effluent limit contained in this Order, the waste should not be designated waste, should not degrade the underlying groundwater, and can be stored in an unlined pond. Finally, the water quality criteria for groundwater are expressed as TDS, not DIS. This use of TDS as an effluent limitation is consistent with other Orders the Board has adopted for food processors within the last few years. This Order must be fully protective of the groundwater and therefore the effluent limitation must be expressed as TDS.