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5.3 Description of all current on-site sources of nitrate to soil and groundwater and the contribution of nitrate load from these sources to the project site: The only source of nitrates are the existing septic system in use by an existing parcel for residential purposes and agriculture. The existing septic system was accounted for when determining the approximate nitrate concentration the site could expect with the proposed development. 5.4 Discussion of all proposed future on-site sources of nitrate to soil and groundwater and the contribution of nitrate load from these sources to the project site: The future use of the site will be residential with a 2 acre parcel. The remaining 154 acres will be used for agricultural purposes. For residential use, the approximate flow rate that is expected to be used is between 50 to 70 gallons per person per day (Crites and Tchobanoglous). The San Joaquin County Environmental Health Department requires that a safety factor of 2 be used. Therefore, the approximate values used should be doubled. As this method of determining nitrate loads is conservative on its own, the value of 70 gallons per person per day was used. This method is conservative as it does not include lateral dispersion or mixing of groundwater. These factors of safety are additional to the County's factor of safety. The existing house three bedrooms and there is a pool house so 4 bedrooms was used in the calculation for a total 560Jgallons per day. The average total nitrogen concentration of domestic waste water is about 20-85 mg/L-N, although 35-45 mg/L-N is a better approximation(Crites and Tchnobanglous). The value selected for this site was 35 mg/L-N. The site will experience a process of denitrification as the soil naturally treats surface material through natural forms. Denitrification is a process that occurs when bacteria uses oxygen in the nitrate(NO3)and release nitrogen(Nz) into the atmosphere. Denitrification can be variable to the type of soils,chemical properties,moisture content and other variables. Although the site has clay material throughout the site, it is expected that a site with soil of these characteristics shall have approximately about 10-15%of denitrification. The value used for this site wash 15%. 5.5 Calculate mass balance of nitrogen loading considering all potential sources identified using Hanztch/Finnemore equation: Using the data mentioned within this report and the attached Soil Suitability Report, the mass balance of nitrogen loading for this site was calculated. This was done using Hanztch/Finnemore formula. Based on the Hanztch/Finnemore equation,the two-acre lot will contain a nitrate load of 8.83 mg/L-N and a flow of 560 gallons per day assuming the parcel is a four bedroom home and using the assumptions mentioned. A flow surpassing that amount could cause an impact to the site's nitrate load and surpass the maximum contaminant level (MCL) of 10.0 mg/L-N for Nitrate in drinking water. 6.0 Discussion of nitrate loading results relative to proposed method of wastewater disposal 6.1 Discussion of total nitrate impact from proposed project: There are very minimal possibilities that the percolating effluent could affect water conditions. The Hanztch/Finnemore equation added to the County's factor of safety of two diminish those risks,but no major additions should be made beyond the proposed improvements mentioned previously without an update to this report. 3