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PRECIPITATION AND Eto DATA FOR TRACY, CA <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 Table 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 December and <br /> January would deep percolation potentially occur. This data illustrates a relatively high potential <br /> for there to be significant evapotranspiration(or bare soil surface evaporation) from a wastewater <br /> disposal system design that may take advantage of evapotranspiration during favorable months of <br /> the year. <br /> NITRATE LOADING STUDY FINDINGS <br /> 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. Domestic flow volume projections have been approximated <br /> from the USEPA Onsite Wastewater Treatment Systems Manual,Pg. 3-4. Residential (domestic) <br /> flow volumes average approximately 69 gallons/person/day. The EHD specifies that each <br /> bedroom has the potential for two people, for an ADF of 140 gpd, 365 dpy. As referenced, the <br /> existing house has three bedrooms and the proposed pre-manufactured home will also have three <br /> bedrooms, for a total of six bedrooms on the subject parcel. Therefore,total flow volume <br /> projection=6 x 140= 840 gallons wastewater/day. <br /> Wastewater Characteristics <br /> Blackwater will originate from toilets and graywater from showers, laundry, teeth brushing, <br /> dishwashing and hand washing. Additional wastewater constituents may consist of other liquids <br /> to the system, such as coffee,juices, etc. <br /> The scientific literature cites nitrogen concentrations in domestic septic effluent typically ranging <br /> from 17 mg N/L for basins, sinks, etc. to 140 mg N/L for toilet wastes. Therefore, taking a <br /> composite of these values, a nitrogen concentration of 62 mg N/L within the septic effluent will <br /> be used to calculate nitrate-nitrogen loading for this project(See Kaplan-Septic Systems <br /> Handbook, Pg. 147). <br /> Page 4 of 13 <br />