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i The following Table illustrates rainfall and evapotranspiration for the Tracy area. Precipitation data was obtained from the Soil_Survey of San Joaquin County. The conservative"2 years in 10"data was used and not the "average rainfall"data. Evapotranspiration data was obtained from the California Irrigation Management Information System(CIMIS): TABLE 6 PRECIPITATION AND,Eto.DATA-FOR�TRACY, Month 2 Years in 10 will have more Eto Average Potential Deep precipitation than: (in/mo) Percolation(in/mo) (in/mo) (in/day) January 2.93 1.55 0.05 1.38 February 2.21 2.24 0.08 -- March 2.38 3.72 0.12 -- April 1.51 5.10 0.17 May 0.71 6.82 0.22 -- June 2.09 7.80 0.26 -- 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 a septic system disposal area. III. NITRATE LOADING STUDY FINDINGS A. WASTEWATER FLOW VOLUME PROJECTIONS AND CHARACTERISTICS In accordance with requirements of the Environmental Health Department for Studies such as this, in which there is no formally proposed project, the Nitrate Loading Study must quantify the number of people (employees, customers, etc. for a commercial project) the subject parcel can support, t without exceeding the MCL for nitrate. 9 Chesney Consulting