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bm V4PW im September 21, 2005 NOA Project Number. E05104A i 3.6 Impact of Nitrate Loading to Nearby Water Sources The result of the nitrate loading balance indicates that the proposed development could potentially cause a buildup of nitrate in the ground water above 10 mg/L-N over the long term. The nitrate loading addresses domestic septic usage from each parcel only. According to the Hantzsche and Fennemore equation and approach there is a potential for a buildup of nitrates in the ground water to 13.9 mg/L-N. 4.0 DISCUSSION OF'NITRATE LOADING RESULTS V 4.1 Total Nitrate Impact According to the Hantzsche and Fennemore equation and approach there is a potential for a buildup of nitrates in the ground water to 13.9 mg/L-N. The actual impact to ground water may actually be less than estimated. The equation assumes full build out (two residences) and full occupation of the property over the life of the property which is a conservative estimate. In addition, Mr. Mike Huggins has indicated to our office in the past that the Morada area, even i' with fairly dense development utilizing on-site septic systems, has not shown a rise of nitrates in ground water as would be expected. He indicated to our office this may be due to the presence of 1� clay layers preventing the migration of effluent down to the aquifer. The adjacent well did indicate ` elevated nitrates however. In general, we agree with this opinion, however, the shallow aquifer may now be experiencing some impact, potentially from septic system usage in the area. 4.2 Methods of Mitigation We would propose that the development of the property could take some steps to minimize nitrate impacts to the ground water. The following steps are proposed to reduce the concentrations nitrates in percolating septic system effluent: • Utilize standard septic system design with the following exceptions. • Minimum Septic Tank Sizes 2 bedroom —1200 3 bedroom —1600 4 bedroom — 2000 5 bedroom — 2400 6 bedroom — 3200'J 7 bedrooms and above will require consultation. WA • Apply 4 inches of compost of peat in the bottom of the leach trenches. Utilize gravel drain systems to improve denitrification. 6 W. '0004 V7