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F NDWATER INFORMATION § 4.1. Groundwater depths and elevations throughout San Joaquin County are aps published by the County Flood Control and Water Conservation District. The es of Equal Depth map (2016) indicates the groundwater depth to be 15 feet, but a recent geotechnical investigation conducted for this project on August 31 of this year determined the water table depth to be 11.5 bgs due to last winter's significant rainfall. A well log for a domestic well on the property south of the subject property illustrates varied geological strata of clay and sand down to a depth of 145 feet, with a clay layer from 17 to 30 feet. A well log for the on-site Monitoring Well also illustrates a clay layer existing from 19 to 25 feet. Groundwater research in the scientific literature references that there may be significant denitrification potential within aquifers or saturated zones composed of a fine-grained soil fraction. SSS§2.1, 4.2. Since the property was part of the former Hayres Chicken Ranch, and since surrounding properties have been intensely farmed for several decades, the probability for nitrate contamination in the underlying soil and groundwater is significant. However, soil and well water analyses indicate very low nitrate concentrations. Calculation of Alkalinity Requirement for Nitrification The nitrate-nitrogen loading calculations on Page 7 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 well 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 82 mg/L, as determined on Page 6 would require: 82 mg/L NHa N x 7.1 mg CaCO3= 582 mg/L alkalinity. The alkalinity in the domestic well water supply was tested to be an extremely low 10 mg/L. Consequently,nitrification may be inhibited to an indeterminable degree. E. SURFACE WATER INFORMATION Storm water management consists of existing on-site retention basins. Percolating stormwater may produce dilution effects to constituents of concern within the underlying water table Climatic Data: Rainfall versus Evapotranspiration NLS§3.2. It is generally and scientifically accepted that when precipitation exceeds evapotranspiration(Eto), deep percolation of surface rainwater may occur. Evapotranspiration refers to water evaporation that takes place both at the soil surface and transpiration by plants. The following Table illustrates rainfall and evapotranspiration for the Stockton area, which is the closest data available. Precipitation data was obtained from the Soil Survey of San Joaquin County. The conservative "2 years in 10" data was used and not the "average rainfall"data. Evapotranspiration data was obtained from the California Irrigation Management Information System (CIMIS): 4 Chesney Consulting