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PRECIPITATION AND Eto DATA FOR TRACY, CA <br /> October 1.06 4.03 0.13 - <br /> November 2.10 2.10 0.07 -- <br /> December 2.3 8 1.5 5 0.05 0 <br /> TOTALS(in.) 13.18 i)� A-,44 <br /> 57.0 ------ r 2.2 <br /> 0 <br /> The Table illustrates that evapotranspiration far exceeds precipitation, even when using higher <br /> rainfall data that exceeds normal rainfall data by 56%. Only i s of December and <br /> January would deep percolation potentially occur. 's data in <br /> a relatively high potential <br /> or there to sign icant evapotranspiration(or bare soil surface evaporation) from a shallow <br /> wastewater disposal system design that may take advantage of evapotranspiration during favorable <br /> months. <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. <br /> Residential (domestic) flow volumes average approximately 69 gallons/person/day. The EHD <br /> specifies that each bedroom has the potential for two people, therefore an ADF of 140 gpd, 365 <br /> dpy. As referenced, the existing house has three bedrooms and the proposed second unit dwelling <br /> will also have three bedrooms. Therefore, total flow volume projection=6 x 140= 840 gallons <br /> 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 /> Chesney Consulting <br />