SR0032706_SSNL - Laserfiche WebLink

Home Browse Search

P Pastor Matt Linden May 5,2003, Page.5 Table 2., Summary of Nitrate Mass Balance Analysis. Scenario Result Acres Average - ' Effluent Leachfield Deep Percolation (Nc)* (A) Daily Concen- Denitrifi- of Rainfall(R) .Flow(Q) tration cation(d) `(Plate 1) (Table 1) (Nw) Standard Septic 5.4 mg/L-N 16.7 436 gpd ' 75 mg/L=N 10% 5.01 in System(Plate 2) OSI Treatment System 3.3 mg/L-N 16.7 436 gpd 38 mg/L-N S% 5.01 in (50%removal of Total Nitrogen)(Plate 3)** OSI Treatment System 2.1 mg/L-N 16.7 436 gpd 19 mg/L-N 5% 5.01 in (75%removal of Total Nitrogen)(Plate 4)** * Maximum contaminate level(MCL)for Nitrate in drinking water is 10 mg/L.-N. ** Please note that 50%removal of nitrogen(75 mgIL-N x 50%)is conservative,nitrogen removal maybe up to 75%+if conditions are optimal according to OSI. Discussion and`Recommendations Because of the sandy conditions,the rapid percolation rate measured, the shallow depth to ground water, and the pre-existing nitrate condition of the ground water, our previous report had recommended the use of an engineered septic system to reduce the nitrate concentration of the effluent in order to minimize the impact to the existing aquifer. Our office has evaluated several treatment•systems and believes the Orenco Advantex system is well suited for the proposed facility. It has a relatively low capital cost, low maintenance cost,reliable, and obtains performance consistency. Considering.that Ireatment goals below'10 mg/L for nitrate are very difficult to achieve and a r greatly dependent on influent concentrations of waste water,we believe that it is much more realistic to . set treatment goals of 50%to 75% total nitrogen reduction-of(Nw)over the long terra. This is what Orenco Systems Inc. AdvanTex system has achieved. Based on the assumptions of the Hantzshe &Finnemore equation, we believe the proposed project will not cause a long term buildup of nitrates above 10 mgIL N in the ground water regardless of the type of septic system. However, a short term build up is possible due to the rapid percolation rate measured,the shallow depth to ground water. 'A water quality test of the aquifer indicates it has been impacted by nitrates_-The use of an OSI AdvanTex treatment-system will greatly reduce these short term: impacts and improve the long term water quality level(Nc)estimated.bythe Hantzshe&Finnemore equation. Our office believes the site is suitable for developmentunitizing.an OSI Advantex wastewater treatment system or.an equivalently performing system. Please refer to the soil suitability/nitrate loading ?�E Rap - r s S w r