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July 21,2003 <br /> Job Number:LG03-120 <br /> Page 11 <br /> Table 2. <br /> _ Summary of Nitrate Mass Balance Analysis. <br /> Scenario Result Acres Average Effluent Leachfield Deep Percolation <br /> (Ne)* (A) Daily Concen- Denitrifi- of Rainfall(R) <br /> Flow(Q) tration cation(d) (Plate 1) <br /> (Table 1) (Nw) <br /> Standard Septic 16.7 mg/L-N 2.0 490 gpd 45 mg/L-N 10% 5.01 in <br /> System(Plate 9) <br /> _ Standard Septic 1.7 mg/L-N 69.8 490 gpd 45 mg/L-N 10% 5.01 in <br /> System Plate 10) <br /> * Maximum contaminate level(MCL)for Nitrate in drinking water is 10 mg/L-N.Estimate does not include the <br /> contribution from agriculture. <br /> As a result of the nitrate loading balance, a 2-acre site which contains a primary residence and <br /> second dwelling unit could potentially cause a build up on nitrate above 10 mg/L-N over the long <br /> term. <br /> 8.0 DISCUSSION AND RECOMMENDATIONS <br /> The site achieved a rapid but satisfactory percolation rate due to the sandy conditions of the site. <br /> _ A water well sample collected from the on site domestic well indicated that the well water has <br /> been negatively impacted from nitrates. The nitrate test indicated a level of 94 mg/L as nitrate <br /> which is well above the Environmental Protection Agency's maximum contaminate level of 45 <br /> mg/L as nitrate. <br /> As a result of the nitrate loading balance, the proposed 2-acre site which may someday contain a <br /> primary residence and second dwelling unit could potentially cause a build up of nitrateaboveID <br /> mg/L-N over the long term in ground water. The soils were found to be quite permeable and <br /> would not provide any significant"blanket"of protection between the septic system disposal � m <br /> field and ground water. Partially treated waste water exiting a conventional septic system will <br /> most likely mix and degrade the quality of ground water. In addition to the septic system,the <br /> application of agricultural fertilizers may degrade the shallow ground water quality to some <br /> -� degree. <br /> It is our experience working with EHD, they view this area as being sensitive to ground water <br /> impacts from septic systems and agriculture and would view the use of a conventional septic <br /> system on the site as unsatisfactory. The nitrate loading calculation would support this view. <br /> N <br /> > n <br /> O � <br /> SSS O G♦ <br />