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TABLE 4 <br /> PRECIPITATION AND Eto DATA FOR TRACY, CA <br /> Month 2 Years in 10 will have more Eto Average Potential Deep <br /> precipitation than: (in/mo) (in/mo) (in/day) Percolation(in/mo) <br /> January 2.93 1.55 0.05 1.38 <br /> February 2.21 2.24 0.08 <br /> March 2.38 3.72 0.12 <br /> April 1.51 5.10 0.17 <br /> May 0.71 6.82 0.22 <br /> June 2.09 7.80 0.26 - <br /> July 0.28 8.68 0.28 <br /> August 1.05 7.75 0.25 <br /> September 0.84 5.70 0.19 <br /> October 1.06 4.03 0.13 <br /> November 2.10 2.10 0.07 <br /> December 2.38 1.55 0.05 0.83 <br /> TOTALS(in.) 13.18 57.0 -- 2.21 <br /> This chart illustrates that evapotranspiration far exceeds precipitation, even when using higher <br /> rainfall data that exceeds normal rainfall data by 56%. Only in the months of January, February, <br /> November and December would deep percolation potentially occur. This data illustrates a relatively <br /> high potential for there to be significant evapotranspiration(or bare soil surface evaporation) from a <br /> wastewater disposal system design that may take advantage of evapotranspiration during favorable <br /> months of the year. <br /> III. NITRATE LOADING STUDY FINDINGS <br /> A. WASTEWATER FLOW VOLUME PROJECTIONS AND CHARACTERISTICS <br /> Wastewater Flow Volume Projections <br /> To determine nitrate-nitrogen loading from any project, wastewater flow volumes must be <br /> determined as accurately as possible. Flow volume projections will be approximated from both the <br /> residential structure and the commercial coach. Typically,residential flows are assigned flow <br /> volumes based on a"per person"or gallons/capita/day. Also commonly used are the number of <br /> bedrooms contained within a residential structure. The San Joaquin County Onsite Wastewater <br /> Disposal Standards uses"number of bedrooms" for design criteria. These criteria will be used in <br /> this report to formulate flow volumes since the number of inhabitants is unknown. <br /> 6 <br />