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WASTE DISCHARGE REQUIREMENTS ORDER NO.R5-2002-0148 -5- MUSCO FAMILY OLIVE COMPANY AND THE STUDLEY COMPANY WASTEWATER TREATMENT AND LAND DISPOSAL FACILITY SAN JOAQUIN COUNTY Discharger will stagger planting, irrigation, and harvest so that there are always two or three crops in the land application areas. 24. The RWD presents several properties and uptake rates for the crops that may be planted at the facility. The properties of these selected crops, as listed in the RWD,are: Crop ET(inches/yr) EC (=ho/cmZ N Uptake(lbs/ac-yr) Salt Uptake(lbs/ac•y�r Sudan Grass 51.4 5,000 325 2,400 Salt Tolerant Alfalfa 54.7 Not Available 480 2,840 Bermuda Grass 51.0 8,500 400 2,700 Winter Barley 13.2 8,500-10,000 160 860 ET denotes evapotranspiration. EC denotes electrical conductivity. N denotes nitrogen. Salt refers to all dissolved solids including plant macronutrients. ' EC as presented in this table references the maximum EC value at which at least 90-percent of yield is anticipated. 25. The RWD describes the annual nitrogen loading rate(due to wastewater application)to be between 428 lbs/ac-year to 490 lbs/ac-year. The Discharger anticipates double cropping Sudan grass or Bermuda grass with winter barley will take up the applied nitrogen. However,crop health at the facility has been poor in areas where wastewater has been applied for longer times and staff are uncertain whether the proposed intensive agriculture can be practiced at this facility in the long term. Therefore,the Monitoring and Reporting Program requires that the Discharger submit an annual report,prepared by a Certified Crop Advisor or Certified Agronomist,detailing the effect of the current and continued application of the wastewater on crops. 26. The RWD describes the annual DIS loading rate to be between 34,000 lbs/ac-year and 40,000 lbs/ac-year. However,the Discharger anticipates only approximately 3,260 lbs/ac-year will be taken up by cropping activities. The RWD states leaching of DIS from the root zone must be performed to control soil salinity at levels that do not lander crop growth. Because the DIS loading rate far exceeds the crop uptake rate,it is anticipated that leaching of DIS will result in interim attenuation of the DIS in the soil, and eventual groundwater degradation with continued application. Therefore,this Order contains an effluent limit,less than that proposed by the Discharger that will protect the underlying groundwater from degradation by salt. 27. The 30 April 2002 RWD presented a water balance that showed that 160 acres of cropped land and use of a 114 million gallon storage pond could accept a yearly average wastewater flow of 1,000,000 gpd. However, this water balance assumed irrigation during times when rainfall exceeds evapotranspiration needs, a 10-percent leaching fraction, and that the facility operates 338 days per year. In addition, some of the calculations did not appear accurate. Staff created its own water balance,based on the 100-year annual rainfall return frequency and irrigation of 200 acres of crops. This water balance shows that Musco can discharge a monthly average of 700,000 gpd of wastewater and stormwater falling on the facility. It should be noted that neither water balance takes into account any contaminated stormwater that must be collected from the land application area and returned to the storage pond.