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October 10,2005 NOA Project Number: E05066A Page,3 /C"/Residential: 280 gallons per day at a concentration of 45 mg/L-N total nitrogen. ommercial: 137 gallons per day at a concentration of 85 mg/L-N total nitrogen. k1 280 gals * 3.785 L/gal = 1,059.8 L, 1,059.8 L* 45 mg/L-N = 47,691 mg-N 137 gals * 3.785 L/gal = 518.5 L 518.5 L* 85 mg/L-N = 44,076.3 mg-N (1) 1,059.8 L 4,7691 mg-N + 518.5 + 4,4076.3 mg-N ,578.3 L 91,767.3 mg-N (2) 91,767.3 mg-N/1,578.3 L /8.1 mg/L-N (co bined wastewater concentration) The quality and quantity of waste water from th has been determined to be 417 gallons (280 + 137 gals) per day and the average concentration of total nitrogen is 58.1 mg/L. These new variables were plugged into the Hantzsche and Fennemore equation used previously in the report. The results are as follows in Table 3. Table 3. Summary of New Nitrate Mass Balance Sccnario. Result Average Daily Effluent Leachfield Deep Percolation of Plate * Acres Flow(Q) Concen- Denitrifi- Rainfall(R) mg/L- (A) (Table 3) tration(Nw)(gpd) (mg/L-N) cation(d) (Plate 9) (in.) 1 8.8 5.07 1 417 1 58.1 1 15% 1 5.-6 Maximum ntamin evel(MCL) for nitrate in drinking water is 10 mg/L-N. The actual calculation is shown on Plate 1 attached to this letter. The result of this scenario indicates that a potential buildup of nitrates in ground water was found to be less than 10 mg/L-N at 8.8 mg/L-N total nitrogen. Generally for planning purposes,it is desirable to have an Nc value below 10 mg/L-N, especially where sandy soils occur and ground water depth is not deep. This scenario assumes the site was using standard septic system technology and no second dwelling residential unit. Our office believes the Nw value of 85 mg/L-N requested by EHD is a conservative (and probably worst case) especially given this method looks a long term impacts. ._Given the information presented,along with the soil conditions and the depth to water,it is our opinion that the site will not cause a buildup of nitrogen in the ground water above 10 m L-N.