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Staff Report -5— Waiver 5Waiver of WDRs for Small Food Processors pH will be buffered and the biochemical oxygen demand will be reduced through microbial activity. This is enhanced by warm weather conditions,which are typical of the food processing season in the Central Valley Region. This waiver applies to those dischargers who dispose of wastewater in this manner. The individual discharger will need to show, through the Report of Waste Discharge, that the particular site contains sufficient land to assimilate the waste. Some example calculations follow: A winery crushing 80 tons of grapes will generate between 27,000 and 121,000 gallons of wastewater. Using conservative values,the winery will generate 100,000 gallons of wastewater on an annual basis, containing 50 mg/I of total nitrogen, 12,000 mg/1 of biochemical oxygen demand (BOD), and 6,000 mg/1 of total dissolved solids (TDS). These values equate to 41 pounds of nitrogen, 10,000 lbs of BOD, and 5,000 lbs of TDS. This waste needs to be spread over sufficient cropland to take up the waste. On a hydraulic loading basis, 100,000 gallons of wastewater equates to approximately 4" of wastewater spread over an acre within a year's time. This is acceptable from a hydraulic and nitrogen loading basis, but would result in an over application of BOD and TDS. Therefore, additional acreage would be required. Individual WDRs for food processing wastewater discharges typically restrict BOD loading rates to no more than 300 lbs BOD/ac for a single day(to prevent nuisance/odor conditions) and an average of 100 lbs BOD/ac over the entire processing season (to prevent water quality degradation). Plants can uptake approximately 2,000 lbs of salt/acre/year. Some of this salt load is provided in the irrigation water and in fertilizer. In the above case, a winery producing 100,000 gallons of wastewater would need to spread the waste evenly over at least 5-6 acres of land (depending on the salt content of the irrigation water, amount of fertilization, the BOD strength of the wastewater during crush, and whether wastewater will be applied to the entire acreage). Each individual discharger will need to describe and/or provide calculations showing the nutrient loading rates, how they plan on applying the wastewater,whether any dilution will take place through the application of irrigation water, how many acres would be necessary to prevent groundwater degradation, how they will ensure that the wastewater is evenly spread over the land, and how they will ensure that the wastewater does not run off into surface waters. The El Dorado Winery Association states that it is developing a"wastewater management model" based on soil characteristics, geology, hydrogeology,and topography. Staff anticipate that wineries that utilize this model could apply for coverage under this waiver, if they meet the size limitations. The model, applied to the specific winery, would supply the information necessary for the Report of Waste Discharge. Specific Prohibitions This waiver does not allow the discharge of wastes from ion exchange units,water softeners, boilers, or any other operation with a potential to create waste containing high concentrations of total dissolved solids. Waste from small food processors contains high concentrations of total dissolved solids, and crops will only uptake a limited amount of salts. In order to protect underlying groundwater, these specific high-strength wastes must be disposed of in a separate manner. Industries that use brining, curing, or caustic solutions in the processing are specifically exempt