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5.2 Description of impact of rainfall contribution of nitrate load to the project site: The impact of rainfall contribution on the project site was completed to detennine the nitrate load. The average monthly precipitation and evapotranspiration are required to calculate the site nitrate load. These two values are used to estimate the deep percolation. The annual rainfall recharge is estimated by analyzing the difference between the monthly average precipitation and the evapotranspiration when the precipitation exceeds the monthly average evapotranspiration. These calculations are attached in the Appendix. The data for the potential evapotranspiration water was obtained from the California Irrigation Management Information System (CIMIS). The project is located within an area designated as Zone 12. Based on the values for this area along with the average monthly precipitation values obtained from the Western regional Climate Center for the region an estimate of the deep percolation of rain for the project was determined. Station 262 in Linden had the most similar weather and soil conditions to our project site. The results for the average rainfall recharge at the site were) 7.5 in./year. The nitrate concentration is estimated to be about 1 mg/L-N. (Hantzche and Finnemore, 1992). 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 systems in use by existing parcel for residential uses. The existing septic systems were considered 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 existing use for this site is agricultural and residential. It is expected that every residence generate 100 gal/day of waste for the first bedroom and 50 gal/day of waste for each subsequent bedroom. Parcel 1 is currently undeveloped, assume a new 2 bedroom primary residence was constructed and a new 1 bedroom secondary residence was constructed. The combined waste on Parcel 1 would be 250 gal/day. Parcel 2 is currently undeveloped, Assume a new 2 bedroom primary residence and a 1 bedroom secondary residence were constructed. The combined waste on Parcel 2 would be 250 gal/day. Parcel 3 currently has a 4 bedroom primary residence and 3 bedroom secondary residence. Parcel 3 generates a total of 450 gal/day. Parcel 4 is currently undeveloped, assume a 2 bedroom primary residence and a 1 bedroom secondary residence, the combined waste on parcel 4 would be 250 gal/day. The total waste generation across the site is 1200 gal/day of waste. This project site can sustain that load as shown on the included calculations. The average total nitrogen concentration of domestic wastewater 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 45 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(N2) into the atmosphere. Denitrification can be variable to the type of soils, chemical properties,moisture content and other variables. Based on the Redding Gravelly and San Joaquin Sandy Loams on site and moderate percolation rates, this site's soil has moderate levels of denitrification. It is expected that a site with soil of these characteristics shall have approximately about 10-20%of denitrification. The value used for this site was 15%. 3 I'