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7E. SURFACE WATER INFORMATION Storm water management will consist of onsite retention and runoff into the adjacent orchards. Percolating stormwater may produce dilution effects to the underlying water table. According to a scientific paper authored by Shaw and Turyk(1994), reduction of nitrate concentrations in groundwater can occur primarily through dispersion, or by percolating rainwater, or a water source including effluent water recharge. Climatic Data: Rainfall versus Evapotranspiration NLS§3.2. Located in Appendix E, is data from CIMIS Station#70 in Manteca. Theoretical deep percolation values are indicated in the right-hand columns for the years 2014 through 2018. Taking a simple average of these five years, a value of 3.6 inches of theoretical deep percolation will be used in the equation below. III. NITRATE LOADING STUDY FINDINGS A. WASTEWATER FLOW VOLUME PROJECTIONS AND CHARACTERISTICS Wastewater Flow Volume Projection To determine nitrate-nitrogen loading from the project,wastewater flow volumes must be determined as accurately as possible. Typically, loading projections are based on the maximum number of employees and customers who may potentially use the toilet/sink,etc. on a workday basis. Wastewater flow volume projections for facilities in unsewered areas have been historically and typically calculated under numerous guidelines and scenarios,as illustrated in the following list: 1. Published Data in the SJC EHD OWTS Standards Federal Standards, and scientific literature. 2. Number of bathroom fixtures correlated with bathroom use per capita. 3. Number of parking spaces. 4. Maximum number of people(e.g.,employees,customers,etc.). 5. Historical wastewater flow data from an existing facility. A. The OWTS Standards assigns 30 gallons per person, per day for Office Buildings. B. The OWTS Standards assign 150 gallons per toilet,per day for employee/public use. The number of employees and customers has been adequately determined as indicated on the attached Water Provision Declaration, found in Appendix F. But this does not determine how often the six Unisex Restrooms(two existing,four proposed)will be used on a daily basis during the operation of the hulling and packing facility. Consequently,the EHD Standard of assigning 150 gallons per toilet,per day is applicable. Unfortunately,this EHD Standard was based on old style toilets using 5 gallons per flush. Contemporary toilets use 1.5 gallons per flush. EHD Wastewater flows projected from one toilet in each of the six Unisex Restrooms are equivalent to 100 flushes per day/toilet: (900 gals/day(6 toilets @ 150 gals/day each)_ 1.5 gals/flush(low flow toilets/flush)=600 flushes/day,or 100 flushes/toilet/day)which incorporates an enormous safety factor,even when accounting for hand-washing. 5 Chesney Consulting