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PRECIPITATION AND Et©DATA FOR TRACY,CA July 0.28 8.68 0.28 -- August 1.05 7.75 0.25 -- September 0.84 5.70 0.19 -- October 1.06 4.03 0.13 -- November 2.10 2.10 0.07 -- December 2.38 1.55 0.05 0.83 TOTALS(in.) 13.18 57.0 ------ 2.21 The Table illustrates that evapotranspiration far exceeds precipitation, even when using higher rainfall data that exceeds normal rainfall data by 28%(10.33 in. vs. 13.18 in.) Only in the months of December and January, and possibly November and February would deep percolation potentially occur. This data illustrates a relatively high potential for there to be significant evapotranspiration (or bare soil surface evaporation)from the filter bed disposal area. 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 will be conservatively ' determined. Typically, loading projections are based on the maximum or total number of employees and customers who may potentially use the toilet/sink,etc.on a workday basis. Several variables are involved in estimating wastewater flows from a facility. 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 San Joaquin County EHD Sewaae Standards and scientific literature. 2. Number of bathroom fixtures correlated with bathroom use per capita for a facility. 3. Number of parking spaces for a facility. 4. Maximum number of people(e.g.,employees, customers,etc.)for a facility. 5. Historical wastewater flow data from an existing facility. A. The Sewage Standards assigns 30 gallons per person for Office Buildings. B. The Sewage Standards assign 150 gallons per toilet fixture for employee/public use. Since it cannot be adequately determined how many people will use the Office Building restroom and the Maintenance Buildings restroom on a daily basis,the Standard of assigning 150 gallons per toilet,per day is applicable. However,this 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 two toilets in both the Office and Maintenance Buildings is equivalent to 400 flushes per day: (600 gals/day(2 toilets @ 150 gals/day x 2 buildings)- 1.5 gals/flush(low flow toilets/flush)=400 flushes/day)which incorporates an enormous safety factor. 6 i Chesney Consulting