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III. NITRATE LOADING-STUDY FINDINGS A." 'GROUNDWATER INFORMATION (SSS§ 4.1,NLS§2.0, §2.1, §2.2,and §2.3:) NLS 21 The_1999 Lines of Equal Depth Map published by-the San Joaquin County Flood Control Distridicates the static groundwater depth to be approximately 65 feet. Lines of Equal Elevation Map from 2003, found in Appendix 6,illustrates the groundwater flow to be in a northwest direction. SSS§ 4.3,4.4;4.5;4.6, NLS 2.3. There is an agricultu ell d near the extreme southwest corner of the property. As noted in the THD Condit' s AP oval, this well.is.non-operational since there is no electricity to it; therefore, it Co d not be to fulfill this portion of the Nitrate Loading/Soil Suitability=Out_of_-1.1The S is will eithe stro this well under EHD permit, or place the well under an EHD ervice pni . _ kali equirement for Nitrification The nitrate-nitrogen loading calculations below are contingent upon the environmental factors required for nitrification to occur. These conditions include soil pore-space-oxygen content, soil _ temperature, pH, electrical conductivity, organic matter, cation-exchange capacity, and alkalinity. Alkalinity in wastewater effluent is derived from the domestic water supply in addition to the introduction of wastes.. Nitrification consumes approximately 7.1 mg of alkalinity for every mg of ammonia-nitrogen (NH4-N) oxidized. Nitrification of the average Total Nitrogen (TN) concentration of 66 inas determined below would require: 66 mg/L NH x 7.1 mg CaCO3 =469 mg/L alkalinity. Therefore, nitrification may be inhibited if the alkalinity in the future domestic water supplies are approximately-196 mg/L and the TN is approximately 66 ppm. B. SURFACE WATER-INFORMATION .Surface water consists of all other water sources originating on the surface of the project, other than septic system effluent. These sources include rainfall, surface runoff, domestic irrigation and E stormwater retention. The San Joaquin-County of Public Works - Isohyetal Map shows 13.5 inches of rainfall to be the Mean Annual Precipitation over the project locale. SSS 2.1 4. ,NLS§ 2.2',!3.1 As the project is built-out, a very small percentage of-the land surface _- - will bei die eably covered with structures, concrete, asphalt, etc. This will have an attenuating effect om surface water (rainfall.and domestic irrigation) on the downward migration of nitrate molecules currently"in-transit' and on nitrate yet to be formed. However, the vast majority of the acreage t will remain open or farmed,thus leaving the nitrate loading potential to probably remain equal to the _ existing potential.- Page -5- Chesney Consulting