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Recommendations of the On -Site Wastewater Treatment Systems Nitrogen Reduction Technology Expert Review Panel February 2014 ' TN reduction beyond STE baseline of 5 kg/person/year. Additional TN reductions will take place in the in situ (soil) treatment unit. BOD = biochemical oxygen demand; ES = effective size; HLR = hydraulic loading rate; IFAS = integrated fixed -film activated sludge; OLR = organic loading rate; UC = uniformity coefficient, HRT = hydraulic retention time; NSF = NSF International; SA = surface area; PE = population equivalent (typically 2 PE/bedroom); gpd = gallons per day; sf = square feet. Table ES -2. Summary of BMP Recommendations for In Situ Soil Treatment Unit Processes. Ex Situ Best Management Reduction Practice Qualifying Conditions Credit' Recirculating media • Timer -based flow equalization with 24-48 doses/day 50% filters • 2' depth media Shallow -placed, pressure -dosed • Sand media: ES = 1.0-5.0 mm; UC:5 2.5; < 0.5% passing 50% dispersal #200 sieve; HLR 5 5 gpd/sf; OLR <_ 5 Ib BOD/1,000 sf • Gravel media. ES = 5.0-20 mm; UC <_ 2.5; < 0.5% passing #200 sieve; HLR 5 15 gpd/sf; OLR 5 15 Ib BOD/1000 sf • Uniform, pressurized distribution 5 6 sf/orifice • Device capable of recirculating 3-5 times forward flow back to anoxic zone Anne Arundel County 2 -day HRT anoxic chamber 50% IFAS . 1 -day HRT aerobic chamber with >_ 600 sf surface area fixed -film media • Aeration device capable of maintaining 3.0 mg/L DO • Device capable of recirculating 3-5 times forward flow back Elevated sand mounds to anoxic zone 50% • Alarm for aeration device fault Proprietary treatment NSF 245 certification or similar > 50% systems . Technology -specific • Percent removal based on qualifying third -party field testing ' TN reduction beyond STE baseline of 5 kg/person/year. Additional TN reductions will take place in the in situ (soil) treatment unit. BOD = biochemical oxygen demand; ES = effective size; HLR = hydraulic loading rate; IFAS = integrated fixed -film activated sludge; OLR = organic loading rate; UC = uniformity coefficient, HRT = hydraulic retention time; NSF = NSF International; SA = surface area; PE = population equivalent (typically 2 PE/bedroom); gpd = gallons per day; sf = square feet. Table ES -2. Summary of BMP Recommendations for In Situ Soil Treatment Unit Processes. OTETRA TECN.INC. 12 In Situ Reduction Best Management Practice Qualifying Conditions Credit' Conventional system (baseline N/A 20% practice) Shallow -placed, pressure -dosed • Drip or LPD installed within 12" of grade in natural 50% dispersal surface horizon (e.g. A or A/B) • Credit not provided where sand or loamy sand soils predominate within 12" below effluent dispersal depth • Lines placed on contour • Drip requires prefiltration system, automatic flush cycle, flow equalization, air release valves • LPD requires: working pressure head of 2-6, dosing volume of 7-10 times distribution system piping, lateral flushing provisions, max flow variation of 10% for each lateral Elevated sand mounds . Installation on intact natural surface horizon (e.g. 50% OTETRA TECN.INC. 12