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Mr. Rodney Estrada <br /> • November 27,2000 <br /> Page 2 <br /> Table of Rain Fall from Various Sources <br /> Source Rain Inches <br /> CfMS*, Lodi 18.22 (11-99 to 10-00) <br /> CIMS*,Manteca 16.02 (11-99 to 10-00) <br /> CIMS*, Modesto 13.59 (11-99 to 10-00) <br /> CIMS*,Patterson 12.57(11-99 to 10-00) <br /> Soil Survey**, 14.19 <br /> Stockton (Long term average) <br /> Soil Survey**, 10.33 <br /> Tracy-Carbona (Long term average) <br /> *For monthly rain fall from CMS stations,see intemet <br /> http://wwwdla.water.ca.gov/cgi-bin/cimis/eimis/data/ <br /> ** Soil Survey of San Joaquin County California,US Department <br /> of Agriculture, Soil Conservation Service. <br /> The rainfall generally decreases southward in the Valley. The City of Manteca is about 15 miles <br /> directly west of Valley Home- The Modesto CMS Station is about 12 miles south. In our opinion,the <br /> CMS Manteca Rain Station more accurately reflects the rainfall in Valley Home then the Modesto CMS <br /> Station. The CMS data (rain and ET)however is only available for the previous 12 months(on their <br /> website). <br /> Our office believes that the Valley Home area probably experiences about 13 inches(13.07-in)of <br /> rain (based on last years levels)and after monthly potential ET is subtracted against monthly rain,about 7 <br /> inches (6.79-in)was estimated to be recharge or deep percolating rainfall- I am still looking for better data <br /> however other rain gauges do not have good corresponding agricultural ET information. <br /> A back calculation was made to determine the least amount of deep percolating rain(recharge) <br /> required for a 1-acre and 2-acre site using the same criteria presented in the report. The result of an <br /> f �f LL additional analysis is--for a-family of-four-(4)on-a one -1 -acre parcel with a.resulting load of 10mg/L N, <br /> the required amount of deep percolating rain is 6.8 inches. The result of an additional analysis for a family <br /> of four(4)on a two(2)acre parcel with a resulting load of l Omg/L-N, required 3.4 inches of deep <br /> percolating rain. Based on the County's two(2)acre minimum requirement,the two(2)acre scenario is <br /> more appropriate. Given the same two(2)acre size lot,four(4)persons,with 6.79 inches(estimated deep <br /> percolation of rain.from Manteca CIMIS),the nitrate load is 5.9 mg/LN about 59%of the maximum <br /> contaminant level for nitrates. A two(2)acre lot has sufficient area to support a typical size house with a <br /> septic system and leach lines. <br /> G <br /> t oE�a y <br /> x W <br /> a <br /> r <br />