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Description: In general terms, infiltration systems can be described as natural or constructed depressions located in permeable soils that capture, store and infiltrate stormwater runoff within 48 hours. These depressions can be located at the surface of the ground (e.g. infiltration basin) or they can be designed as underground facilities (e.g. structural chamber or excavated pit filled with aggregate such as an infiltration trench). Typically, infiltration systems are designed with one or more pre- treatment facilities or they are designed as off-line facilities. Infiltration systems should be located in permeable soils and a minimum 3 -foot distance is REQUIRED from the bottom of the practice to the seasonally high water table, bedrock or other impeding layer per the Minnesota Pollution Control Agency Construction General Permit (CGP). Dry wells and Trenches should be designed to handle the smaller, more frequent rainfall events. Stormwater associated with the larger rainfall events should bypass these practices by a separate pipe or an overflow device. Infiltration basins and underground infiltration systems should be designed to handle both the water quality volume and as the water quantity volume. Infiltration systems can be designed to address a number of stormwater management issues including: water quality, stormwater runoff reduction, flow attenuation, thermal impacts to cold water fisheries, and ground water recharge. Duration of Storm Event- Storage & filtration/infiltration Following{ Storm Event- Remaining storage draw -down Courtesy of Rice Creek Watershed District SITE FACTORS •SEQUENCE Drainagr; Areas. Start of Storm Event - Initial runoff & storage 155 50 Ar t,1ax Dry Well/ -french/ Ba:, n Max. Site Slope 3' Min. Depth to Bedrock Min. Depth to Seasonally 3.. High Water Table MRCS Soil Type c, use loll lv l -d I4.t3,G'.$ D' I nlillrll un ab lily but t, n hr usc•J lu 1111101 1'-,3 �� r; ' � I`V fel) 11 L'I ll CUI1cIll 711 �' poor - roes) Freeze/ Thaw Suitability Description: In general terms, infiltration systems can be described as natural or constructed depressions located in permeable soils that capture, store and infiltrate stormwater runoff within 48 hours. These depressions can be located at the surface of the ground (e.g. infiltration basin) or they can be designed as underground facilities (e.g. structural chamber or excavated pit filled with aggregate such as an infiltration trench). Typically, infiltration systems are designed with one or more pre- treatment facilities or they are designed as off-line facilities. Infiltration systems should be located in permeable soils and a minimum 3 -foot distance is REQUIRED from the bottom of the practice to the seasonally high water table, bedrock or other impeding layer per the Minnesota Pollution Control Agency Construction General Permit (CGP). Dry wells and Trenches should be designed to handle the smaller, more frequent rainfall events. Stormwater associated with the larger rainfall events should bypass these practices by a separate pipe or an overflow device. Infiltration basins and underground infiltration systems should be designed to handle both the water quality volume and as the water quantity volume. Infiltration systems can be designed to address a number of stormwater management issues including: water quality, stormwater runoff reduction, flow attenuation, thermal impacts to cold water fisheries, and ground water recharge. Duration of Storm Event- Storage & filtration/infiltration Following{ Storm Event- Remaining storage draw -down Courtesy of Rice Creek Watershed District