SU0008143 SSNL - Laserfiche WebLink

Home Browse Search

Discussion of Nitrate Loading Results Total Nitrate Impact Based on the method and assumptions described, the result of the nitrate loading estimate indicates that the existing and proposed residences and proposed devel engin the Site have the tential to cause a buildup of nitrates in the aquifer above 10 mg/L-N up to 14.68 m6141- . The small property size and the over estimation of customer-and emplov� has caused the nitrate loading estimate to be above 10 mg/L-N. We believe that the aquifer below the site will not likely experience the estimated buildup of nitrate due to the conservative assumptions this model utilizes and for the �) following reasons: 1. The facility will likely not see up to 20 winery customers per day, 7 days per week, 12 months per year. It is our opinion that the level may actually be one or two customers per day average over the entire year. The owner indicated that most of the time, only one or two staff will be working; these are the same people living onsite already. Taking into consideration these factors, the resulting Nc value would be reduced from 14.68 to 10.6 m /g L,N. 2. Mixing_ of_the percolating effluent with ground water tends to dilute the concentration_an_d greatly reduces potential buildup of nitrogen. The percolation rate of 42 minutes per inch is a relatively slow rate and will tend to keep the moisture near the surface longer so evaporation and plant transpiration will uptake the nutrients and moisture, especially during the warm months. (IJP„ / ,(. , _ -/- -• e-! 1 ) 3. Ground water in the area is not known to have been impacted significantly by percolating septic system effluent. Nitrate was detected in the sample from the on-site well at a concentration of 16.9 mg/L-NO3 (equivalent to 3.6 mg/L- N). 4. If an oversized septic tank were utilized.for the new winery bathroom, the tank would allow greater waste-water retention that would promote the biologic treatment of waste water, improving effluent water quality. Studies by the industry and other informal studies within the county by EHD staff and consultants have shown this to be a very cost effective way to improve treatment. The oversized septic tank will improve overall water quality of the percolating effluent when compared to a tank that was sized using traditional methods. LOGE1013 Page 13