SR0080748 SSNL - Laserfiche WebLink

Home Browse Search

TABLE 3 WATER TABLE (WT) UNDERLYING EFFLUENT DISPOSAL AREA: ANALYTICAL RESULTS OF TESTED CONSTITUENTS SAMPLE 11) NITRATE TOTAL TOTAL TOTAL Ec pH KJELDAHL NITROGEN ALKALINITY NITROGEN (TKN) BDG J WT 85.1 mg/L 28 mg/L 113 mg/L 400 mg/L 41.1 mmhos/cm 6.9 NLS§ 2.3, SSS§ 4.3, 4.4, 4.5, 4.6. There are no on-site domestic or irrigation wells on the subject Parcel to be sampled to quantify nitrate concentrations from the lower aquifers. Domestic water from the City of Tracy will be supplied for this project. Calculation of Alkalinity Requirement for Nitrification The nitrate -nitrogen loading from the wastewater effluent and the indigenous soil nitrogen is 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 City of Tracy well water, 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 Total Kjeldahl Nitrogen (TKN) concentration of 146 mg/L, from a septic tank sample that serves the existing Holly Commerce Center as discussed below, would require: 146 mg/L NH4-N x 7.1 mg CaCO3 =1,037 mg/L alkalinity. The alkalinity concentration in the City water is unknown, but certainly lower than 400 mg/L found in the groundwater. Therefore, there is an insufficient alkalinity for complete nitrification to readily proceed without the introduction of wastes and the alkalinity within the soil environment. E. SURFACE WATER INFORMATION Storm water drainage management will be by on-site retention as engineered by Siegfried. Rainwater storage will theoretically provide a water table dilution effect to percolating wastewater effluent although this effect is indeterminable since the water table elevation and directional flow is variable throughout the entire project site. As referenced in the next Section, rainfall in comparison to evapotranspiration is minimal. 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 Tracy area. Precipitation data was obtained from the Soil Survey of San Joaquin Countv. The conservative "2 years in 10" data was used and not the "average rainfall" data. -5- Chesney Consulting