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STAFF REPORT • • 4 MUSCO FAMILY OLIVE COMPANY AND THE STUDLEY COMPANY CONSIDERATION OF WDRS AND A C&A ORDER 6 September 2002 Regional Board Agenda The most recent water balance was submitted with the 8 August 2002 response to the tentative WDRs. In general, the water balance fails to demonstrate adequate wastewater storage and application capacity for the requested a flow rate of 800,000 gpd. Evaluation of the water balance is complicated by the poor data regarding stormwater runoff and tailwater generation rates. However, because the Discharger can stop operations and limit wastewater flow if needed to prevent overflows of wastewater from the storage pond, staff are recommending the Discharger be allowed the requested flow limit—with some additional restrictions. In the discussion below, the water balance is reviewed and the additional restrictions are described. Water Balance Review In preparation of the tentative WDRs, the Discharger has submitted water balances prepared by Kennedy Jenks. Since the original water balance was submitted in the 30 April 2002 RWM, two conference calls to discuss the contents of the water balances have been held. In addition, the Discharger has revealed the actual size of the wastewater storage pond to be 84.1-million gallons (Mgal) (nearly 30-Mgal less than originally stated). This evaluation focuses on Table 2 "Water Balance for 100 Year Rainfall Event Climate Conditions". The water balance addresses some of staff s concerns regarding previously submitted water balances but fails to demonstrate adequate storage capacity for the wastewater flow rate as proposed. In general, the water balance is overly optimistic—especially considering the problems the Discharger has experienced with controlling tailwater at the site. However, because of the nature of the olive processing activities, the facility can stop production if necessary and wait for better climatic conditions. The water balance indicates wastewater will be stored during the winter months of December, January, and February and applied to land application areas the rest of the year. During the months when wastewater is stored, stormwater that falls on upland application areas is proposed to be bypassed past the storage pond. (Stormwater that falls on the main facility will continue to be discharged to the storage pond). However, the Discharger has not proposed criteria for bypassing stormwater. As written, the tentative WDRs prohibit bypass until the Discharger provides acceptable criteria to show that wastewater will not be present in the stormwater. The ability to bypass wastewater is a critical assumption in the water balance and may impact the Discharger's ability to operate. The water balance includes application of wastewater in months when rainfall exceeds evapotranspiration (ET). Such an application is likely to result in considerable generation of tailwater, all of which is required to be collected. For example, March rainfall is 4.1 inches, potential ET is 3.0 inches, yet 5.2 inches of wastewater(approximately 35.3 Mgal) is proposed for application. The water balance's failure to adequately address tailwater generation that might result from such an application is described below. The water balance is optimistic in calculating the tailwater generation rate and is inconsistent when calculating tailwater generation rates and stormwater runoff. The tailwater generation rate