SR0085029_SSNL - Laserfiche WebLink

Home Browse Search

5.4 Discussion of all proposed future on-site sources of nitrate to soil and groundwater and the contribution of nitrate load from these sources to the project site: The existing use for this site is residential. Given the three bedroom home, it is expected they generate 100 gals/day for the first room and 50 gals/day for every subsequent room. Assuming a new three bedroom home, that would generate a total of 400 gal/day. This project site can sustain that maximum as shown on the included calculations. The average total nitrogen concentration of domestic wastewater is about 20-85 mg/L-N, although 35-45 mg/L-N is a better approximation (Crites and Tchnobanglous). The value selected for this site was 35 mg/L-N. The site will experience a process of denitrification as the soil naturally treats surface material through natural forms. Denitrification is a process that occurs when bacteria uses oxygen in the nitrate (NO3) and release nitrogen (N2) into the atmosphere. Denitrification can be variable to the type of soils, chemical properties, moisture content and other variables. Based on the sandy loams on site and the high percolation rates, this site's soil has low levels of denitrification. It is expected that a site with soil of these characteristics shall have approximately about 10-15% of denitrification. The value used for this site was 15%. 5.5 Calculate mass balance of nitrogen loading considering all potential sources identified using Hanztch/Finnemore equation: Using the data mentioned within this report and the attached Soil Suitability Report the mass balance of nitrogen loading for this site was calculated, this was done using Hanztch/Finnemore formula. Based on the Hanztch/Finnemore equation this 3 acre site would contain a Nitrate Load (Nc) of 8.32 mg/L-N. The site can handle approximately 500 gal/day, a flow surpassing that amount could cause an impact to the site's nitrate load and surpass the maximum contaminant level (MCL) of 10.0 mg/L-N for Nitrate in drinking water. 6.0 Discussion of nitrate loadinr results relative to proposed method of wastewater disposal 6.1 Discussion of total nitrate impact from proposed project: There are possibilities that the percolating effluent could affect water conditions. The Hanztch/Finnemore equation has an added to the factor of safety which is not accounted for as it does not include lateral dispursment in its calculations diminishing those risks, but no major additions should be made beyond the proposed improvements mentioned previously without an update to this report. 6.2 Description of the methods proposed to mitigate any known or future impact to soil and groundwater from nitrate and/or other constituents of concern, at anti/or around the project site: The project, as described in this report is sustainable by the site in current conditions. Additions or modifications to the site may require the addition of a wastewater treatment system. At the time an addition is proposed, this report should be updated to ensure the adequate improvements are made.