(e.g., clays). Filter fabric can be added to inlet protection devices using coarse stone or aggregate to enhance sediment removal. However, the possibility of increased ponding should be considered. The following table summarizes expected performance for an array of typical water quantity and quality target constituents for storm drain inlet protection BMPs that are properly designed, installed, and maintained. Table 21. Expected performance for storm drain inlet protection Water Quantity Flow attenuation Runoff volume reduction Water Quality Pollution prevention Soil erosion Sediment control Nutrient loading Pollutant removal suspended solids Total phosphorus Heavy metals Floatables Oil and grease Primary design benefit Secondary design benefit Little or no design benefit Planning Considerations Install inlet protection devices before upslope soil disturbance occurs. In newly developed areas, inlet protection should be placed immediately after the storm sewer inlets are installed. It is critical that the storm sewer inlet not be completely blocked by inlet protection when public safety is a concern. Inlet protection should only be used in locations where sediment can be removed and temporary ponding will not create a public safety hazard or cause property damage. Blocking an inlet can cause streets to flood and sediment to build up. Select inlet protection devices that do not pond water where adjacent areas are open to traffic. Examples of these include low-profile filter berms and filters suspended in the inlet structure. Because inlet protection devices are high-maintenance BMPs, ensure that up-gradient soil stabilization, perimeter protection, and other erosion control practices are in place to minimize the amount of sediment in stormwater flowing to inlets. Note that straw bales are not approved as inlet BMPs. Design Performance of all of inlet protection depends on proper installation and use of materials. Materials should be checked for conformance with applicable MnDOT specifications. Inlet protection devices can be fabricated from clean aggregate, filter fabric, or other materials, or an appropriate device can be selected from the many commercial products available for construction site stormwater management. As noted above, devices that are bulky (e.g., concrete block) or that result in deeply ponded water and
(e.g., clays). Filter fabric can be added to inlet protection devices using coarse stone or aggregate to enhance sediment removal. However, the possibility of increased ponding should be considered. The following table summarizes expected performance for an array of typical water quantity and quality target constituents for storm drain inlet protection BMPs that are properly designed, installed, and maintained. Table 21. Expected performance for storm drain inlet protection Water Quantity Flow attenuation Runoff volume reduction Water Quality Pollution prevention Soil erosion Sediment control Nutrient loading Pollutant removal suspended solids Total phosphorus Heavy metals Floatables Oil and grease Primary design benefit Secondary design benefit Little or no design benefit Planning Considerations Install inlet protection devices before upslope soil disturbance occurs. In newly developed areas, inlet protection should be placed immediately after the storm sewer inlets are installed. It is critical that the storm sewer inlet not be completely blocked by inlet protection when public safety is a concern. Inlet protection should only be used in locations where sediment can be removed and temporary ponding will not create a public safety hazard or cause property damage. Blocking an inlet can cause streets to flood and sediment to build up. Select inlet protection devices that do not pond water where adjacent areas are open to traffic. Examples of these include low-profile filter berms and filters suspended in the inlet structure. Because inlet protection devices are high-maintenance BMPs, ensure that up-gradient soil stabilization, perimeter protection, and other erosion control practices are in place to minimize the amount of sediment in stormwater flowing to inlets. Note that straw bales are not approved as inlet BMPs. Design Performance of all of inlet protection depends on proper installation and use of materials. Materials should be checked for conformance with applicable MnDOT specifications. Inlet protection devices can be fabricated from clean aggregate, filter fabric, or other materials, or an appropriate device can be selected from the many commercial products available for construction site stormwater management. As noted above, devices that are bulky (e.g., concrete block) or that result in deeply ponded water and
Barrier-controls_Inlet-protection_Outlet-energy.docx