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TABLE 1 SOIL PROFILE CHARACTERISTICS AND ANALYTICAL TEST RESULTS SAMPLE I.D. DEPTH SOIL TEXTURE SOIL NITRATE- pH CLASSIFICATION NITROGEN CATION EXCHANGE CAPACITY AND SAND SILT AND CONTENT ORGANIC MATTER % CLAY PERCENTAGES DISPOSAL, AREA Sand- Clay Loam 7 ppm NO, -N 8.1 19.8 meq/100g 1.3% 36" DEPTH4C% 30% 34% The soil information and data illustrate a native soil of a comparatively high clay content and an organic matter percentage of 1.3. Although this OM percentage is somewhat low in agricultural soils, the dark black native soils will provide OM to promote denitrification. The alkaline pH is relatively optimum for nitrification, however the high clay content creates anaerobic micro -sites preventing nitrification and promoting denitrification of nitrified ammonium. Therefore, it is my professional opinion that the native soils provide a denitrification (and mitigation of nitrification) factor of 40%. NITRATE LOADING STUDY ADDENDUM - FINDINGS WASTEWATER CHARACTERISTICS The wastewater characteristics are anticipated to be those normally found in typical domestic or household systems. The nitrogen concentration of 45 mg/L N used in the AGE Report will be used below in the nitrate loading calculations. Additionally, the recommendation of installing a 2,000 gallon septic tank instead of the required 1,200 gallon tank will reduce nitrogen concentrations on the following premise: Wastewater researchers place the nitrogen reduction occurring in septic tanks at 10% to 20%. From the September 2004 Symposium "University Curriculum Development for Decentralized Wastewater Management - Onsite Nitrogen Removal," Dr. Stuart Oakley of California State University Chico states that "approximately 20% of the total nitrogen generated is removed in the septic tank" (Ref. 4). If Dr. Oakley's premise of an approximate 20% nitrogen removal occurs in septic tanks, then if the tank size is increased a specific percentage from a baseline size, then it is reasonable to assume that that percentage increase in tank size will remove that percentage of nitrogen above the 20% baseline. This nitrogen removal occurs from anaerobic digestion of organic material and scheduled tank pumping. Therefore, increasing the tank size for this project from the required 1,200 gallon to 2,000 gallon is a 67% increase in capacity, thus substantiating a 67% increase above this 20% N reduction: 20% + (20 x 0.67) = 33% decrease in nitrogen concentrations by installing a 2,000 gallon tank in lieu of a 1,200 gallon tank. This percentage decrease will be used in the nitrate loading calculations below. Page 2 of 7 Chesney Consulting