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D. GROUNDWATER INFORMATION NLS§ 2.1, SSS§ 4.1. Groundwater depths and elevations throughout San Joaquin Count' are illustrated on maps published by the County Flood Control and Water Conservation District. The 1993 Lines of Equal Depth Map indicate the depth to the water table was approximately 35 ft. The 1999 Lines of Equal Depth Map illustrates the water table to be approximately 40 ft. These two years are regarded as the highest (shallowest) depths to groundwater on record. The Spring 2018 Lines of Equal Depth Map illustrate an approximate 53 ft depth to the water table revealing a significant drop in elevation due to excessive pumping and limited recharge during serious drought periods. Consequently, sufficient distance exists between the anticipated soil -effluent interface and the highest anticipated depth to groundwater. From the Spring 2018 Lines of Equal Elevation Maps, groundwater directional flow is in a north -northwesterly direction. NLS§ 2.2, 3.1, SSS§ 2.1, 4.2. Properties to the north, south, east and west are currently in agricultural production, commercial/industrial and rural residential. Considering this area was farmed for decades, there is a significant potential for nitrate contamination of the underlying groundwater from nitrogen fertilizer applications and residual organic matter decomposition. However, nitrate testing conducted on the onsite well water indicates the nitrate -nitrogen concentration at low concentrations. It is assumed the depths of the onsite wells are comparatively deep and pumping water from deep aquifers that have not been impacted with nitrate. NLS§ 2.3, SSS§ 4.3, 4.4, 4.5, 4.6. Since the winery is classified as a Small Public Water System, a water sample was not obtained from one of the onsite active domestic wells pursuant to EHD requirements. The EHD does require however, a California Drinking Water Watch document, found in the original SSNL Studies. Calculation on the Alkalinity Requirement for Nitrification The nitrate -nitrogen loading calculations 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 water source, in addition to the introduction of wastes. Nitrification consumes approximately 7.1 mg of alkalinity for every mg of arrmonia- nitrogen (NH4 N) oxidized. From the original testing protocol, an approximate deficient value of 251 mg/L of additional alkalinity must come from the soil, or other sources, to provide a sufficient concentration for nitrification of the effluent. Of significant importance is the lack of alkalinity in the effluent receiving soils, which are highly acidic. This low pH will unquestionably irr_pede nitrification. However, nitrification may occur at the deeper depths where alkalinity is present. E. SURFACE WATER INFORMATION NLS§ 3.2. To simplify Net Rainfall Recharge (NRR), a water balance document from Norman Hantzsche (one of the authors of the nitrate loading equation) is found in Appendix D. The data illustrates a water balance NRR of 8.82" for the Stockton area, and is therefore applicable for this project. Page -4- Chesney Consulting