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L September 21, 2005 <br /> NOA Project Number: E05104A <br /> L3.6 Impact of Nitrate Loading to Nearby Water Sources <br /> The result of the nitrate loading balance indicates that the proposed development could potentially <br /> cause a buildup of nitrate in the ground water above 10 mg/L-N over the long term. The nitrate <br /> loading addresses domestic septic usage from each parcel only. According to the Hantzsche and L) <br /> Fennemore equation and approach there is a potential for a buildup of nitrates in the ground water <br /> to 13.9 mg/L-N. <br /> r <br /> 4.0 DISCUSSION OF NITRATE LOADING RESULTS <br /> 4.1 Total Nitrate Impact <br /> LAccording to the Hantzsche and Fennemore equation and approach there is a potential for a <br /> buildup of nitrates in the ground water to 13.9 mg/L-N. The actual impact to ground water may <br /> actually be less than estimated. The equation assumes full build out (two residences) and full <br /> occupation of the property over the life of the property which is a conservative estimate. <br /> In addition, Mr. Mike Huggins has indicated to our office in the past that the Morada area, even <br /> with fairly dense development utilizing on-site septic systems,has not shown a rise of nitrates in <br /> ground water as would be expected. He indicated to our office this may be due to the presence of <br /> Lclay layers preventing the migration of effluent down to the aquifer. The adjacent well did indicate <br /> elevated nitrates however. In general,we agree with this opinion, however, the shallow aquifer may <br /> now be experiencing some impact,potentially from septic system usage in the area. <br /> L4.2 Methods of Mitigation <br /> LWe would propose that the development of the property could take some steps to minimize nitrate <br /> impacts to the ground water. The following steps are proposed to reduce the concentrations nitrates <br /> in percolating septic system effluent: <br /> LUtilize standard septic system design with the following exceptions. <br /> LMinimum Septic Tank Sizes <br /> 2 bedroom— 1200 <br /> 3 bedroom— 1600 <br /> L 4 bedroom—2000 <br /> 5 bedroom—2400 <br /> 6 bedroom—3200 <br /> 7 bedrooms and above will require consultation. <br /> • Apply 4 inches of compost of peat in the bottom of the leach trenches. Utilize <br /> gravel drain systems to improve denitrification. <br /> 6 <br />