Difference between revisions of "Summary of permit requirements for bioretention"
Summary of permit requirements for bioretention

Revision as of 16:55, 19 August 2018

The following are requirements of the Construction Stormwater General Permit.

Permittees must design infiltration systems such that pre-existing hydrologic conditions of wetlands in the vicinity are not impacted (e.g., inundation or breaching a perched water table supporting a wetland).
Permittees must not excavate infiltration systems to final grade, or within three (3) feet of final grade, until the contributing drainage area has been constructed and fully stabilized unless they provide rigorous erosion prevention and sediment controls (e.g., diversion berms) to keep sediment and runoff completely away from the infiltration area.
When excavating an infiltration system to within three (3) feet of final grade, permittees must stake off and mark the area so heavy construction vehicles or equipment do not compact the soil in the infiltration area.
Permittees must use a pretreatment device such as a vegetated filter strip, forebay, or water quality inlet (e.g., grit chamber) to remove solids, floating materials, and oil and grease from the runoff, to the maximum extent practicable, before the system routes stormwater to the infiltration system.
Permittees must design infiltration systems to provide a water quality volume (calculated as an instantaneous volume) of one (1) inch of runoff, or one (1) inch minus the volume of stormwater treated by another system on the site, from the net increase of impervious surfaces created by the project.
Permittees must design the infiltration system to discharge all stormwater (including stormwater in excess of the water quality volume) routed to the system through the uppermost soil surface or engineered media surface within 48 hours. Permittees must route additional flows that cannot infiltrate within 48 hours to bypass the system through a stabilized discharge point.
Permittees must provide a means to visually verify the infiltration system is discharging through the soil surface or filter media surface within 48 hours or less.
Permittees must provide at least one soil boring, test pit or infiltrometer test in the location of the infiltration practice for determining infiltration rates.
For design purposes, permittees must divide field measured infiltration rates by 2 as a safety factor or permittees can use soil-boring results with the infiltration rate chart in the Minnesota Stormwater Manual to determine design infiltration rates. When soil borings indicate type A soils, permittees should perform field measurements to verify the rate is not above 8.3 inches per hour. This permit prohibits infiltration if the field measured infiltration rate is above 8.3 inches per hour.
Permittees must employ appropriate on-site testing ensure a minimum of three (3) feet of separation from the seasonally saturated soils (or from bedrock) and the bottom of the proposed infiltration system.
Permittees must design a maintenance access, typically eight (8) feet wide, for the infiltration system.
This permit prohibits permittees from constructing infiltration systems that receive runoff from vehicle fueling and maintenance areas including construction of infiltration systems not required by this permit.
This permit prohibits permittees from constructing infiltration systems where infiltrating stormwater may mobilize high levels of contaminants in soil or groundwater. Permittees must either complete the MPCA's contamination screening checklist or conduct their own assessment to determine the suitability for infiltration. Permittees must retain the checklist or assessment with the SWPPP.

For more information and to access the MPCA's "contamination screening checklist" see the Minnesota Stormwater Manual.

This permit prohibits permittees from constructing infiltration systems in areas where soil infiltration rates (including amended soils) are field measured at more than 8.3 inches per hour unless they amend soils to slow the infiltration rate below 8.3 inches per hour.
This permit prohibits permittees from constructing infiltration systems in areas with less than three (3) feet of separation distance from the bottom of the infiltration system to the elevation of the seasonally saturated soils or the top of bedrock.
This permit prohibits permittees from constructing infiltration systems in areas of predominately Hydrologic Soil Group type D soils (clay).
This permit prohibits permittees from constructing infiltration systems within a Drinking Water Supply Management Area (DWSMA) as defined in Minn. R. 4720.5100, subp. 13, if the system will be located:

a. in an Emergency Response Area (ERA) within a DWSMA classified as having high or very high vulnerability as defined by the Minnesota Department of Health; or

b. in an ERA within a DWSMA classified as moderate vulnerability unless a regulated MS4 Permittee performed or approved a higher level of engineering review sufficient to provide a functioning treatment system and to prevent adverse impacts to groundwater; or

c. outside of an ERA within a DWSMA classified as having high or very high vulnerability, unless a regulated MS4 Permittee performed or approved a higher level of engineering review sufficient to provide a functioning treatment system and to prevent adverse impacts to groundwater.

See "higher level of engineering review" in the Minnesota Stormwater Manual for more information.

This permit prohibits permittees from constructing infiltration systems in areas within 1,000 feet upgradient or 100 feet downgradient of active karst features.
This permit prohibits permittees from constructing infiltration systems in areas that receive runoff from the following industrial facilities not authorized to infiltrate stormwater under the NPDES stormwater permit for industrial activities: automobile salvage yards; scrap recycling and waste recycling facilities; hazardous waste treatment, storage, or disposal facilities; or air transportation facilities that conduct deicing activities.

Filtration systems (biofiltration)

Permittees must not install filter media until they construct and fully stabilize the contributing drainage area unless they provide rigorous erosion prevention and sediment controls (e.g., diversion berms) to keep sediment and runoff completely away from the filtration area.
Permittees must design filtration systems to remove at least 80 percent of TSS.
Permittees must use a pretreatment device such as a vegetated filter strip, small sedimentation basin, water quality inlet, forebay or hydrodynamic separator to remove settleable solids, floating materials, and oils and grease from the runoff, to the maximum extent practicable, before runoff enters the filtration system.
Permittees must design filtration systems to treat a water quality volume (calculated as an instantaneous volume) of one (1) inch of runoff, or one (1) inch minus the volume of stormwater treated by another system on the site, from the net increase of impervious surfaces created by the project.
Permittees must design the filtration system to discharge all stormwater (including stormwater in excess of the water quality volume) routed to the system through the uppermost soil surface or engineered media surface within 48 hours. Additional flows that the system cannot filter within 48 hours must bypass the system or discharge through an emergency overflow.
Permittees must design the filtration system to provide a means to visually verify the system is discharging through the soil surface or filter media within 48 hours.
Permittees must employ appropriate on-site testing to ensure a minimum of three (3) feet of separation between the seasonally saturated soils (or from bedrock) and the bottom of the proposed filtration system.
Permittees must ensure that filtration systems with less than three (3) feet of separation between seasonally saturated soils or from bedrock are constructed with an impermeable liner.
The permittees must design a maintenance access, typically eight (8) feet wide, for the filtration system.

Related pages

@@ Line 1: / Line 1: @@
-The following are requirements of the [http://www.pca.state.mn.us/index.php/water/water-types-and-programs/stormwater/construction-stormwater/index.html Construction Stormwater General Permit].
+The following are requirements of the [https://stormwater.pca.state.mn.us/index.php?title=2018_Minnesota_Construction_Stormwater_Permit Construction Stormwater General Permit].
-*A separation distance of 3 feet is required between the bottom of the bioretention practice and the elevation of the seasonally high water table ([[Glossary#S|saturated soil]]) or top of bedrock (i.e. there must be a minimum of 3 feet of undisturbed soil beneath the infiltration practice and the seasonally high water table or top of bedrock).
+[https://stormwater.pca.state.mn.us/index.php?title=MN_CSW_Permit_Section_16_Infiltration_Systems '''Infiltration systems''']
-*To prevent clogging of the infiltration or filtration system with trash, gross solids, and particulate matter, use of a [[Pre-treatment|pretreatment]] device such as a [[Vegetated filter strips|vegetated filter strip]], [[Filtration|vegetated swale]], small sedimentation basin (forebay), or water quality inlet (e.g., grit chamber) to settle particulates before the stormwater discharges into the infiltration or filtration system is required.
+*Permittees must design infiltration systems such that pre-existing hydrologic conditions of wetlands in the vicinity are not impacted (e.g., inundation or breaching a perched water table supporting a wetland).
-*Bioretention practices shall discharge through the soil or filter media in 48 hours or less. Additional flows that cannot be infiltrated or filtered in 48 hours should be routed to bypass the system through a stabilized discharge point. The period of inundation is defined as the time from the high water level in the practice to 1 to 2 inches above the bottom of the facility. This criterion was established to provide the following: wet-dry cycling between rainfall events; unsuitable mosquito breeding habitat; suitable habitat for vegetation; aerobic conditions; and storage for back-to-back precipitation events.
+*Permittees must not excavate infiltration systems to final grade, or within three (3) feet of final grade, until the contributing drainage area has been constructed and fully stabilized unless they provide rigorous erosion prevention and sediment controls (e.g., diversion berms) to keep sediment and runoff completely away from the infiltration area.
-*It is required that impervious area construction is completed and pervious areas established with dense and healthy vegetation prior to introduction of stormwater into a bioretention practice.
+*When excavating an infiltration system to within three (3) feet of final grade, permittees must stake off and mark the area so heavy construction vehicles or equipment do not compact the soil in the infiltration area.
-*If the bioretention practice must comply with the CSW permit, the following prohibitions apply:
+*Permittees must use a [https://stormwater.pca.state.mn.us/index.php?title=Pretreatment pretreatment device] such as a vegetated filter strip, forebay, or water quality inlet (e.g., grit chamber) to remove solids, floating materials, and oil and grease from the runoff, to the maximum extent practicable, before the system routes stormwater to the infiltration system.
-**areas that receive discharges from vehicle fueling and maintenance;
+*Permittees must design infiltration systems to provide a [https://stormwater.pca.state.mn.us/index.php?title=Water_quality_criteria water quality volume] (calculated as an instantaneous volume) of one (1) inch of runoff, or one (1) inch minus the volume of stormwater treated by another system on the site, from the net increase of impervious surfaces created by the project.
-**areas with less than three (3) feet of separation distance from the bottom of the infiltration system to the elevation of the seasonally saturated soils or the top of bedrock;
+*Permittees must design the infiltration system to discharge all stormwater (including stormwater in excess of the water quality volume) routed to the system through the uppermost soil surface or engineered media surface within 48 hours. Permittees must route additional flows that cannot infiltrate within 48 hours to bypass the system through a stabilized discharge point.
-**areas that receive discharges from industrial facilities which are not authorized to infiltrate industrial stormwater under an NPDES/SDS [http://www.pca.state.mn.us/index.php/water/water-types-and-programs/stormwater/industrial-stormwater/index.html Industrial Stormwater Permit] issued by the MPCA;
+*Permittees must provide a means to visually verify the infiltration system is discharging through the soil surface or filter media surface within 48 hours or less.
-**areas where high levels of contaminants in soil or groundwater will be mobilized by the infiltrating stormwater;
+*Permittees must provide at least one [https://stormwater.pca.state.mn.us/index.php?title=Understanding_and_interpreting_soils_and_soil_boring_reports_for_infiltration_BMPs soil boring], test pit or [https://stormwater.pca.state.mn.us/index.php?title=Determining_soil_infiltration_rates infiltrometer test] in the location of the infiltration practice for determining infiltration rates.
-**areas of predominately [[Glossary#H|Hydrologic Soil Group]] D (clay) soils;
+*For design purposes, permittees must divide field measured infiltration rates by 2 as a safety factor or permittees can use soil-boring results with the [https://stormwater.pca.state.mn.us/index.php?title=Design_infiltration_rates infiltration rate chart in the Minnesota Stormwater Manual] to determine design infiltration rates. When soil borings indicate type A soils, permittees should perform field measurements to verify the rate is not above 8.3 inches per hour.  This permit prohibits infiltration if the field measured infiltration rate is above 8.3 inches per hour.
-**areas within 1,000 feet up‐gradient, or 100 feet down‐gradient of active [[Karst|karst]] features;
+*Permittees must employ appropriate on-site testing ensure a [https://stormwater.pca.state.mn.us/index.php?title=Shallow_soils_and_shallow_depth_to_bedrock minimum of three (3) feet of separation] from the seasonally saturated soils (or from bedrock) and the bottom of the proposed infiltration system.
-**areas within a [https://stormwater.pca.state.mn.us/index.php?title=Guidance_for_using_the_Stormwater_Special_and_impaired_waters_search_tool Drinking Water Supply Management Area] (DWSMA) as defined in Minn. R. 4720.5100, subp. 13, if the system will be located:
+*Permittees must design a maintenance access, typically eight (8) feet wide, for the infiltration system.
-***in an [https://stormwater.pca.state.mn.us/index.php?title=Guidance_for_using_the_Stormwater_Special_and_impaired_waters_search_tool Emergency Response Area (ERA) within a DWSMA] classified as having high or very high vulnerability as defined by the Minnesota Department of Health; or
+*This permit prohibits permittees from constructing infiltration systems that receive runoff from vehicle fueling and maintenance areas including construction of infiltration systems not required by this permit.
-***in an ERA within a DWSMA classified as moderate vulnerability unless a regulated MS4 Permittee performed or approved a [https://stormwater.pca.state.mn.us/index.php?title=Guidance_and_recommendations_for_conducting_a_higher_level_of_engineering_review_for_stormwater_infiltration_in_DWSMAs_and_Wellhead_Protection_Areas higher level of engineering review] sufficient to provide a functioning treatment system and to prevent adverse impacts to groundwater; or
+*This permit prohibits permittees from constructing infiltration systems where infiltrating stormwater may mobilize high levels of contaminants in soil or groundwater. Permittees must either complete the [https://stormwater.pca.state.mn.us/index.php?title=File:Contamination_screening_checklist_for_stormwater_infiltration_July_2016.xlsx MPCA's contamination screening checklist] or conduct their own assessment to determine the suitability for infiltration. Permittees must retain the checklist or assessment with the SWPPP.
-***outside of an ERA within a DWSMA classified as having high or very high vulnerability, unless a regulated MS4 Permittee performed or approved a higher level of engineering review sufficient to provide a functioning treatment system and to prevent adverse impacts to groundwater.; and
-**areas where soil infiltration rates are more than 8.3 inches per hour unless soils are amended to slow the infiltration rate below 8.3 inches per hour.
+For more information and to access the MPCA's "contamination screening checklist" [https://stormwater.pca.state.mn.us/index.php?title=Stormwater_Infiltration_and_soil/groundwater_contamination:_A_guide_to_the_Construction_Stormwater_Permit_requirements see the Minnesota Stormwater Manual].
-*If the bioretention practice is being designed to meet the requirements of the MPCA Permit, the required treatment volume is the water quality volume V<sub>(wq)</sub> of 1 inch of runoff from the new impervious surfaces created from the project, calculated as an instantaneous volume. If part of the overall V<sub>wq</sub> is to be treated by other BMPs, subtract that portion from the V<sub>wq</sub> to determine the part of the V<sub>wq</sub> to be treated by the bioretention practice. Retrofit and supplemental systems do not need to meet this requirement, provided new impervious surfaces are not created.
+*This permit prohibits permittees from constructing infiltration systems in areas where [https://stormwater.pca.state.mn.us/index.php?title=Guidance_for_amending_soils_with_rapid_or_high_infiltration_rates soil infiltration rates] (including amended soils) are field measured at more than 8.3 inches per hour unless they amend soils to slow the infiltration rate below 8.3 inches per hour.
-*Select the design infiltration rate from [[Design infiltration rates|the table]] based on the least permeable soil horizon within the first 3 feet below the bottom elevation of the proposed infiltration practice.
+*This permit prohibits permittees from constructing infiltration systems in areas with less than [https://stormwater.pca.state.mn.us/index.php?title=Shallow_soils_and_shallow_depth_to_bedrock three (3) feet of separation distance] from the bottom of the infiltration system to the elevation of the seasonally saturated soils or the top of bedrock.
-*[[Design criteria for bioretention#Determine site infiltration rates (for facilities with infiltration and/or recharge)|Field-measured infiltration rates]] shall be divided by a safety factor of 2.
+*This permit prohibits permittees from constructing infiltration systems in areas of [https://stormwater.pca.state.mn.us/index.php?title=Soils_with_low_infiltration_capacity predominately Hydrologic Soil Group type D soils] (clay).
-*Some form of dry or wet pre-treatment is required prior to the discharge of stormwater into the bioretention practice, to remove any sediment and fines that may result in clogging of the soils in the sediment basin area.
+*This permit prohibits permittees from constructing infiltration systems within a [https://stormwater.pca.state.mn.us/index.php?title=Guidance_for_using_the_Stormwater_Special_and_impaired_waters_search_tool Drinking Water Supply Management Area] (DWSMA) as defined in Minn. R. 4720.5100, subp. 13, if the system will be located:
-*Since most bioretention systems are not designed for quantity control they generally do not have peak discharge limits. However outflow must be limited such that erosion does not occur down gradient.
+:a. in an [https://stormwater.pca.state.mn.us/index.php?title=Guidance_for_using_the_Stormwater_Special_and_impaired_waters_search_tool Emergency Response Area (ERA) within a DWSMA] classified as having high or very high vulnerability as defined by the Minnesota Department of Health; or
+:b. in an ERA within a DWSMA classified as moderate vulnerability unless a regulated MS4 Permittee performed or approved a higher level of engineering review sufficient to provide a functioning treatment system and to prevent adverse impacts to groundwater; or
+:c. outside of an ERA within a DWSMA classified as having high or very high vulnerability, unless a regulated MS4 Permittee performed or approved a higher level of engineering review sufficient to provide a functioning treatment system and to prevent adverse impacts to groundwater.
+See "[https://stormwater.pca.state.mn.us/index.php?title=Guidance_and_recommendations_for_conducting_a_higher_level_of_engineering_review_for_stormwater_infiltration_in_DWSMAs_and_Wellhead_Protection_Areas higher level of engineering review]" in the Minnesota Stormwater Manual for more information.
+*This permit prohibits permittees from constructing infiltration systems in areas within 1,000 feet upgradient or 100 feet downgradient of [[Karst|active karst features]].
+*This permit prohibits permittees from constructing infiltration systems in areas that receive runoff from the following [https://stormwater.pca.state.mn.us/index.php?title=Stormwater_infiltration_at_permitted_industrial_stormwater_facilities industrial facilities] not authorized to infiltrate stormwater under the NPDES stormwater permit for industrial activities: automobile salvage yards; scrap recycling and waste recycling facilities; hazardous waste treatment, storage, or disposal facilities; or air transportation facilities that conduct deicing activities.
+[https://stormwater.pca.state.mn.us/index.php?title=MN_CSW_Permit_Section_17_Filtration_Systems '''Filtration systems (biofiltration)''']
+*Permittees must not install filter media until they construct and fully [https://stormwater.pca.state.mn.us/index.php?title=MN_CSW_Permit_Section_25_Definitions#25.30 stabilize] the contributing drainage area unless they provide rigorous [https://stormwater.pca.state.mn.us/index.php?title=MN_CSW_Permit_Section_25_Definitions#25.9 erosion prevention] and [https://stormwater.pca.state.mn.us/index.php?title=MN_CSW_Permit_Section_25_Definitions#25.29 sediment controls] (e.g., diversion berms) to keep sediment and runoff completely away from the filtration area.
+*Permittees must design filtration systems to remove at least 80 percent of TSS.
+*Permittees must use a pretreatment device such as a vegetated filter strip, small sedimentation basin, water quality inlet, forebay or hydrodynamic separator to remove settleable solids, floating materials, and oils and grease from the runoff, to the maximum extent practicable, before runoff enters the filtration system.
+*Permittees must design filtration systems to treat a [https://stormwater.pca.state.mn.us/index.php?title=MN_CSW_Permit_Section_25_Definitions#25.36 water quality volume] (calculated as an instantaneous volume) of one (1) inch of runoff, or one (1) inch minus the volume of stormwater treated by another system on the site, from the net increase of [https://stormwater.pca.state.mn.us/index.php?title=MN_CSW_Permit_Section_25_Definitions#25.15 impervious surfaces] created by the [https://stormwater.pca.state.mn.us/index.php?title=MN_CSW_Permit_Section_25_Definitions#25.24 project].
+*Permittees must design the filtration system to discharge all stormwater (including stormwater in excess of the water quality volume) routed to the system through the uppermost soil surface or engineered media surface within 48 hours. Additional flows that the system cannot filter within 48 hours must bypass the system or discharge through an emergency overflow.
+*Permittees must design the filtration system to provide a means to visually verify the system is discharging through the soil surface or filter media within 48 hours.
+*Permittees must employ appropriate on-site testing to ensure a minimum of three (3) feet of separation between the seasonally saturated soils (or from bedrock) and the bottom of the proposed filtration system.
+*Permittees must ensure that filtration systems with less than three (3) feet of separation between seasonally saturated soils or from bedrock are constructed with an impermeable liner.
+*The permittees must design a maintenance access, typically eight (8) feet wide, for the filtration system.
 <noinclude>

Difference between revisions of "Summary of permit requirements for bioretention" Summary of permit requirements for bioretention

Revision as of 16:55, 19 August 2018

Related pages

Difference between revisions of "Summary of permit requirements for bioretention"
Summary of permit requirements for bioretention