Laserfiche WebLink
LOGE 1714: Delicato SS/NLS Addendum Page 2 <br /> July 18, 2017 <br /> The Hantzsche and Finnemore equation is a conservative approximation of ground-water <br /> nitrate-nitrogen concentration resulting from the combined effect of on-site sewage disposal <br /> systems and precipitation of rain. The equation and method is for estimation of long-term <br /> effect ground-water quality, and is not intended for prediction of seasonal changes (Hantzsche <br /> and Finnemore, 1992). <br /> The method takes into account the development area, soil denitrification factor, rainfall, rainfall <br /> nitrate concentration, waste effluent quantity, and waste effluent nitrate concentration from on- <br /> site septic systems. No contribution from crop irrigation or any soil amendments is considered <br /> for the Hantzsche/Finnemore method. It is reasonably assumed that the irrigation and soil <br /> amendments would be applied at close to agronomic rates for a net balance of plant irrigation <br /> and nutrients. <br /> Mass Transport Soil Properties <br /> The percolation tests have revealed that the surface soils are permeable. The soil will allow <br /> infiltration of water through the surface soils. The longer the effluent remains near the surface, <br /> the more biologic treatment may occur. If permeable soils exist to the depth of the ground <br /> water aquifer, it is possible that any remaining surface contaminants may be transported to the <br /> first saturated zone of the aquifer. <br /> Sources of Nitrate <br /> Septic systems and dairies have been found to be the most significant sources of nitrate in <br /> ground water. Orchards that require fertilization in sandy soils are also a significant source of <br /> nitrate contamination in shallow or sandy aquifers in San Joaquin County. <br /> Contribution of Rainfall <br /> An estimate of the quantity and quality of rainfall was required for the nitrate loading analysis. <br /> The Hantzsche and Finnemore method utilizes the "average recharge rate of rainfall' in <br /> calculating potential nitrate impacts to the aquifer. Not all rainfall will percolate into the aquifer; <br /> evapotranspiration, the sum of evaporation and plant transpiration, will significantly reduce <br /> percolating effluent, especially in summer months. <br /> Rainfall recharge (deep percolation of rain) is a significant factor in the nitrate loading estimate; <br /> however, data on rainfall recharge rates are not widely available. Hantzsche and Finnemore <br /> present average rainfall versus estimated rainfall recharge data for three locations in California: <br />