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[[file:Construction 1.jpg|300px|thumb|alt=construction stormwater image</alt>]]
  
This document provides guidance on how to comply with the site plan review process in the Minnesota Pollution Control Agency’s (MPCA) Authorization to Discharge Stormwater Associated with Small Municipal Separate Storm Sewer Systems (MS4) under the National Pollutant Discharge Elimination System/State Disposal System (NPDES/SDS) Permit Program ([https://stormwater.pca.state.mn.us/index.php?title=MS4_General_Permit| MS4 Permit]). The MS4 Permit requires you, the permittee, to perform and document site plan reviews for construction projects that disturb one acre or more of land to ensure active and post-construction requirements of your regulatory mechanism (e.g. code, ordinance, law) are met. The MS4 Permit requires your regulatory mechanism to be as stringent as the Authorization to Discharge Stormwater Associated with Construction Activity under the NPDES/SDS Program general permit ([https://stormwater.pca.state.mn.us/index.php/Construction_stormwater_permit| MNR100001/Construction Stormwater Permit]).  
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The [[Glossary#M|Municipal Separate Storm Sewer System]] (MS4) [MS4 Staff Site Plan Review Guidance permit requires the permittee to conduct site plan reviews]. Permittees must perform and document site plan reviews for construction projects that disturb one acre or more of land. The site plan review ensures active and post-construction requirements of a permittee's regulatory mechanism (e.g. code, ordinance, law) are met. The MS4 Permit requires the regulatory mechanism to be as stringent as the [https://stormwater.pca.state.mn.us/index.php/Construction_stormwater_permit MNR100001/Construction Stormwater Permit].
  
The items identified below are the minimum that must be evaluated during your stormwater site plan review under the MS4 and Construction Stormwater Permits. For each site plan review performed, you must document the project name, location, total acreage to be disturbed, owner and operator of the proposed construction activity, and any stormwater related comments used to approve or deny the project. If you’d like to conduct a more comprehensive review, please see the MPCA’s SWPPP Checklist. During the site plan review, you must verify that site plans include (an) acceptable:
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This permit requirement is somewhat vague and has led to people not realizing that they need to review plans for specific items. The items identified below are the minimum that must be evaluated during a stormwater site plan review under the MS4 and Construction Stormwater Permits. For each site plan review performed, permittees must document the project name, location, total acreage to be disturbed, owner and operator of the proposed construction activity, and any stormwater related comments used to approve or deny the project. If you’d like to conduct a more comprehensive review, please see the MPCA’s [https://www.pca.state.mn.us/sites/default/files/wq-strm2-47.pdf Stormwater Pollution Protection Plan (SWPPP) Checklist]. During the site plan review, you must verify that site plans include the information listed on this page.
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[[media:SitePlanReviewGuidance.pdf| Here's a PDF version of this page]]
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{{alert|The permittee’s Regulatory Mechanism(s) shall require that owners and operators of construction activity develop site plans that must be submitted to the permittee for review and approval, prior to the start of construction activity. Site plans must be kept up-to-date by the owners and operators of construction activity with regard to stormwater runoff controls. The Regulatory Mechanism(s) must require that site plans incorporate the following erosion and sediment controls and waste controls as described in the above referenced permit:
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(1) BMPs to minimize erosion<br>
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(2) BMPs to minimize the discharge of sediment and other pollutants<br>
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(3) BMPs for dewatering activities<br>
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(4) Site inspections and records of rainfall events<br>
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(5) BMP maintenance<br>
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(6) Management of solid and hazardous wastes on each project site<br>
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(7) Final stabilization upon the completion of construction activity, including the use of perennial vegetative cover on all exposed soils or other equivalent means<br>
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(8) Criteria for the use of temporary sediment basins<br>
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 +
The program shall include written procedures for site plan reviews conducted by the permittee prior to the start of construction activity, to ensure compliance with requirements of the Regulatory Mechanism(s). The site plan review procedure shall include notification to owners and operators proposing construction activity of the need to apply for and obtain coverage under the Agency’s general permit to Discharge Stormwater Associated with Construction Activity No.MN R100001.|alert-danger}}
  
 
==Best Management Practices (BMPs) to minimize erosion==  
 
==Best Management Practices (BMPs) to minimize erosion==  
{| class="wikitable" style="float:right; margin-left: 10px; width:500px"
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{| class="wikitable" style="float:right; margin-left: 10px; width:500px; border: 2px solid white"
|-  
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|- style="border: 2px solid white"
 
! style="background: #d0e5f5" | Stabilization schedule must be no less than:
 
! style="background: #d0e5f5" | Stabilization schedule must be no less than:
|-  
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|- style="border: 2px solid white"
 
| style="background: #f1f5fc" |14 days for all exposed soils
 
| style="background: #f1f5fc" |14 days for all exposed soils
|-  
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|- style="border: 2px solid white"
 
| style="background: #E6F2FF" | 7 days if a discharge point is within one mile of a special  or impaired water
 
| style="background: #E6F2FF" | 7 days if a discharge point is within one mile of a special  or impaired water
|-  
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|- style="border: 2px solid white"
 
| style="background: #f1f5fc" | 24 hours for areas within 200 ft of a public water during fish spawning times
 
| style="background: #f1f5fc" | 24 hours for areas within 200 ft of a public water during fish spawning times
|-  
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|- style="border: 2px solid white"
 
| style="background: #E6F2FF" | 24 hours for areas of ditches and swales within 200 ft of the property edge or surface water discharge point and 14 days for remainder
 
| style="background: #E6F2FF" | 24 hours for areas of ditches and swales within 200 ft of the property edge or surface water discharge point and 14 days for remainder
 
|}  
 
|}  
*[https://stormwater.pca.state.mn.us/index.php?title=Erosion_prevention_practices| Erosion control BMPs]
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*[https://stormwater.pca.state.mn.us/index.php?title=Construction_stormwater_best_management_practice_%E2%80%93_Site_stabilization| Schedule & effective methods to immediately stabilize soil]  
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[[File:Mulch stabilized slope 1.jpg|300px|thumb|alt=mulch stabilized slope|<font size=3>Example of properly stabilized site.</font size>]]
*[https://stormwater.pca.state.mn.us/index.php?title=Sediment_control_practices_-_Outlet_energy_dissipation| Energy dissipation at pipe outlets]<br>
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*100 foot or more buffer from a [https://stormwater.pca.state.mn.us/index.php?title=Special_Waters_and_Impaired_Waters| special or impaired water] <br>
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[https://stormwater.pca.state.mn.us/index.php?title=General_principles_for_erosion_prevention_and_sediment_control_at_construction_sites_in_Minnesota BMPs to minimize erosion] are the first line of defense for protecting stormwater from sediment running off your site. Soil without proper erosion control, such as blanket, mulch, or vegetation is prone to erosion. When reviewing site plans, ensure effective erosion control methods are described and located in the appropriate areas.
*Schedule to stabilize drainage ditches or swales<br>
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*[https://stormwater.pca.state.mn.us/index.php?title=Erosion_prevention_practices Erosion control BMPs]
*Plan to route water around unstabilized areas<br>
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**[[Erosion prevention practices - temporary seeding and stabilization|Temporary seeding and stabilization]]
*Plan to discharge water from BMPs to vegetated areas<br>
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**[[Erosion prevention practices - natural and synthetic mulches|Erosion prevention practices - natural and synthetic mulches]]
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**[[Erosion prevention practices - tackifiers and soil stabilizers|Tackifiers and soil stabilizers]]
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**[[Erosion prevention practices - erosion control blankets and anchoring devices|Erosion control blankets and anchoring devices]]
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**[[Erosion prevention practices - turf reinforcement mats|Turf reinforcement mats]]
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*[https://stormwater.pca.state.mn.us/index.php?title=Construction_stormwater_best_management_practice_%E2%80%93_Site_stabilization Schedule and effective methods to immediately stabilize soil]  
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*[https://stormwater.pca.state.mn.us/index.php?title=Sediment_control_practices_-_Outlet_energy_dissipation Energy dissipation at pipe outlets]
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*100 foot or more buffer from a [https://stormwater.pca.state.mn.us/index.php?title=Special_Waters_and_Impaired_Waters special or impaired water]
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*Schedule to stabilize drainage ditches or swales
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*Plan to route water around unstabilized areas
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*Plan to discharge water from BMPs to vegetated areas
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 +
 
 +
For more information on site stabilization see [https://stormwater.pca.state.mn.us/index.php?title=Construction_stormwater_best_management_practice_%E2%80%93_Site_stabilization this page].
  
 
==BMPs to minimize the discharge of sediment and other pollutants==
 
==BMPs to minimize the discharge of sediment and other pollutants==
* [https://stormwater.pca.state.mn.us/index.php?title=Sediment_control_practices_-_Perimeter_controls_for_disturbed_areas| Downgradient perimeter control]<br>
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[[File:DSC00240.JPG|300 px|thumb|alt=photo silt fence|<font size=3>Photo of a well-constructed silt fence, which is a perimeter control practice.</font size>]]
* [https://stormwater.pca.state.mn.us/index.php?title=Sediment_control_practices_-_Storm_drain_inlet_protection| Storm drain inlet protection]<br>
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* Sediment control for temporary soil stockpiles<br>
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Properly installed and maintained sediment control BMPs, such as silt fence or bioroll, prevent sediment from discharging from your site. They allow stormwater to pass through, but filter out sediment. When reviewing site plans, ensure that sediment controls to be used will be effective for the scale of the site.
* [https://stormwater.pca.state.mn.us/index.php?title=Sediment_control_practices_-_Vehicle_tracking_BMPs| Vehicle tracking BMPs]<br>
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*[https://stormwater.pca.state.mn.us/index.php?title=Sediment_control_practices Sediment control practices]
* Temporary sedimentation basins, if applicable<br>
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**[[Sediment control practices - Vehicle tracking BMPs|Vehicle tracking BMPs]]
* 50 foot buffer maintained adjacent to surface waters or redundant sediment controls otherwise<br>
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**[[Sediment control practices - Perimeter controls for disturbed areas|Perimeter controls for disturbed areas]]
* [https://stormwater.pca.state.mn.us/index.php?title=Chemical_treatment| Plan for using polymers or flocculants] if conventional erosion and sediment controls cannot be used:<br>
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**[[Sediment control practices - Check dams (ditch checks, ditch dikes)|Check dams (ditch checks, ditch dikes)]]
** Chemicals must be appropriate for the soil type<br>
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**[[Sediment control practices - Diversion barrier controls (cofferdams/temporary dikes)|Diversion barrier controls (cofferdams/temporary dikes)]]
** Chemicals must be used and dosed correctly<br>
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**[[Sediment control practices - Storm drain inlet protection|Storm drain inlet protection]]
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**[[Sediment control practices - Outlet energy dissipation|Outlet energy dissipation]]
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*Sediment control for temporary soil stockpiles
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*Temporary sedimentation basins, if applicable
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*50 foot [https://stormwater.pca.state.mn.us/index.php?title=Glossary#B buffer] maintained adjacent to surface waters or redundant sediment controls otherwise
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*[https://stormwater.pca.state.mn.us/index.php?title=Chemical_treatment Plan for using polymers or flocculants] if conventional erosion and sediment controls cannot be used:
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**Chemicals must be appropriate for the soil type
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**Chemicals must be used and dosed correctly
  
 
==Site inspections and rainfall records==
 
==Site inspections and rainfall records==
 
{| class="wikitable" style="float:right; margin-left: 10px; width:500px;"  
 
{| class="wikitable" style="float:right; margin-left: 10px; width:500px;"  
|-
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|-style="border: 2px solid white"
 
! style="background: #d0e5f5" | Insepction schedule must be no less than:
 
! style="background: #d0e5f5" | Insepction schedule must be no less than:
|-
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|-style="border: 2px solid white"
 
| style="background: #f1f5fc" | Every 7 days during active construction
 
| style="background: #f1f5fc" | Every 7 days during active construction
|-
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|-style="border: 2px solid white"
 
| style="background: #E6F2FF" | Within 24 hours after a 0.5 inch rain event
 
| style="background: #E6F2FF" | Within 24 hours after a 0.5 inch rain event
|-
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|-style="border: 2px solid white"
 
| style="background: #f1f5fc" | If work is suspended due to frozen ground, inspections must begin within 24 hours after runoff occurs or construction starts
 
| style="background: #f1f5fc" | If work is suspended due to frozen ground, inspections must begin within 24 hours after runoff occurs or construction starts
|-
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|-style="border: 2px solid white"
 
| style="background: #E6F2FF" | For parts of the site with permanent cover but work is ongoing elsewhere, inspections can be once per month  
 
| style="background: #E6F2FF" | For parts of the site with permanent cover but work is ongoing elsewhere, inspections can be once per month  
|-
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|-style="border: 2px solid white"
 
| style="background: #f1f5fc" | If the entire site has permanaent cover and there is no active construction, inspections can be once per month for twelve months
 
| style="background: #f1f5fc" | If the entire site has permanaent cover and there is no active construction, inspections can be once per month for twelve months
 
|}
 
|}
* Schedule for inspecting & recording inspections<br>
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* Documentation of inspections, including:<br>
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Site inspections must be conducted by a trained person every seven days and within 24 hours of a rainfall event equal to or greater than 1/2 inch. The Construction Stormwater stormwater pollution prevention plan (SWPPP) should document the person responsible for site inspections and any modified inspection frequency.
** date and time of inspection<br>
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*Schedule for inspecting and recording inspections
** inspector name<br>
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*Documentation of inspections, including:
** inspection findings and corrective actions<br>
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**date and time of inspection
** recent rainfall events of 0.5 inches in 24 hours<br>
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**inspector name
** observed discharge and discharge points<br>
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**inspection findings and corrective actions
** proposed amendments to the site plan<br>
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**recent rainfall events of 0.5 inches in 24 hours
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**observed discharge and discharge points
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**proposed amendments to the site plan
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 +
See here for MPCA's [https://www.pca.state.mn.us/sites/default/files/wq-strm2-36.doc construction stormwater inspection checklist]
  
 
==BMPs for dewatering activities==
 
==BMPs for dewatering activities==
* Plan to discharge sediment-laden water to a sedimentation basin<br>
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When done correctly, dewatering activities will only discharge clear water. Therefore, when applicable, Construction Stormwater stormwater pollution prevention plans (SWPPPs) should include the following.
* Plan for dewatering to prevent:<br>
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*A plan to discharge sediment-laden water to a sedimentation basin
** discharge of sediment laden water, <br>
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*A plan for dewatering to prevent discharge of sediment laden water, erosion, and downstream impacts
** erosion and downstream impacts<br>
 
  
 
==BMP maintenance==
 
==BMP maintenance==
 
{| class="wikitable" style="float:right; margin-left: 10px; width:500px;"
 
{| class="wikitable" style="float:right; margin-left: 10px; width:500px;"
|-
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|-style="border: 2px solid white"
 
! style="background: #d0e5f5" | BMP maintenance schedule must be no less than:
 
! style="background: #d0e5f5" | BMP maintenance schedule must be no less than:
|-
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|-style="border: 2px solid white"
 
| style="background: #f1f5fc" | End of next business day for nonfunctioning BMPs
 
| style="background: #f1f5fc" | End of next business day for nonfunctioning BMPs
|-
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|-style="border: 2px solid white"
 
| style="background: #E6F2FF" | End of next business day or as soon as conditions allow for nonfunctioning perimeter control
 
| style="background: #E6F2FF" | End of next business day or as soon as conditions allow for nonfunctioning perimeter control
|-
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|-style="border: 2px solid white"
 
| style="background: #f1f5fc" | 72 hours or as soon as conditions allow for draining sedimentation basins
 
| style="background: #f1f5fc" | 72 hours or as soon as conditions allow for draining sedimentation basins
|-
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|-style="border: 2px solid white"
 
| style="background: #E6F2FF" | 24 hours for tracked sediment
 
| style="background: #E6F2FF" | 24 hours for tracked sediment
|-
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|-style="border: 2px solid white"
 
| style="background: #f1f5fc" | 7 days for removing deltas and sediment from surface water and restabiliztion
 
| style="background: #f1f5fc" | 7 days for removing deltas and sediment from surface water and restabiliztion
 
|}
 
|}
* Schedule and procedure to repair and replace adjusted and non-functioning BMPs or perimeter control devices when sediment reaches ½ the device height<br>
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Sediment control devices are only effective if properly maintained. Ensure Construction Stormwater stormwater pollution prevention plans (SWPPPs) note the following schedules and procedures.
* Schedule to inspect surface waters and streets<br>
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*Schedule and procedure to repair and replace adjusted and non-functioning BMPs or perimeter control devices when sediment reaches ½ the device height
* Schedule and procedure to maintain sediment basins <br>
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*Schedule to inspect surface waters and streets
* Procedure to remove tracked sediment <br>
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*Schedule and procedure to maintain sediment basins
* Schedule to inspect infiltration areas <br>
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*Procedure to remove tracked sediment
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*Schedule to inspect infiltration areas
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For information on specific construction BMPs go to the ''Inspection and maintenance'' section for individual [[Erosion prevention practices]] or [[Sediment control practices]].
  
 
==Management of solid and hazardous waste==
 
==Management of solid and hazardous waste==
*Cover on building products, pesticides, herbicides, insecticides, fertilizers, chemicals, and landscape materials<br>
 
*Plan for properly storing and disposing of waste<br>
 
 
{| class="wikitable" style="float:right; margin-left: 10px; width:500px;"
 
{| class="wikitable" style="float:right; margin-left: 10px; width:500px;"
|-
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|-style="border: 2px solid white"
 
! style="background: #d0e5f5" | Washout operations specifications:
 
! style="background: #d0e5f5" | Washout operations specifications:
|-
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|-style="border: 2px solid white"
 
| style="background: #f1f5fc" | Washout wastes must not contact the ground
 
| style="background: #f1f5fc" | Washout wastes must not contact the ground
|-
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|-style="border: 2px solid white"
 
| style="background: #E6F2FF" | Washout operations must not result in runoff
 
| style="background: #E6F2FF" | Washout operations must not result in runoff
 
|}
 
|}
*Securing portable toilets<br>
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*Process for containing washout wastes<br>
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Properly storing, handling, and disposing of chemicals and building materials protects stormwater. Construction Stormwater stormwater pollution prevention plans (SWPPPs) must include methods to prevent chemicals from coming in contact with stormwater.
*Defined limited area for [https://stormwater.pca.state.mn.us/index.php?title=MS4_fact_sheet_-_Vehicle_Washing| vehicle washing], fueling, and maintenance and a plan to contain washing runoff <br>
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*Cover on building products, pesticides, herbicides, insecticides, fertilizers, chemicals, and landscape materials
*Prohibition of engine degreasing onsite<br>
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*Plan for properly storing and disposing of waste
 +
*Securing portable toilets
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*Process for containing washout wastes
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*Defined limited area for [https://stormwater.pca.state.mn.us/index.php?title=MS4_fact_sheet_-_Vehicle_Washing vehicle washing], fueling, and maintenance and a plan to contain washing runoff  
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*Prohibition of engine degreasing onsite
 +
For more information [https://stormwater.pca.state.mn.us/index.php?title=MS4_fact_sheet_-_Hazardous_Material_Storage_%26_Handling link here].
  
 
==Final stabilization when construction is complete==
 
==Final stabilization when construction is complete==
* Process for stabilizing soils with 70% perennial cover and ditches with permanent cover<br>
+
[[File:Dry swale with check dams complete with trees.png|thumb|250 px|alt=Infiltration practice complete with trees|<font size=3>Infiltration practice following site closure, complete with trees.</font size>]]
* Process for cleaning sediment basins and conveyance systems of accumulated sediment<br>
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* Removal of temporary erosion & sediment control BMPs <br>
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Final stabilization will provide long-term protection from sediment loss. Construction Stormwater stormwater pollution prevention plan (SWPPPs) must provide a final stabilzation plan.
* For residential construction: plan to complete temporary erosion protection and downgradient perimeter control before the property is sold<br>
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*Process for stabilizing soils with 70 percent perennial cover and ditches with permanent cover
* [https://www.pca.state.mn.us/water/crop-production-npdessds-permitted-sites| For construction on agricultural land: the land must be returned to its preconstruction use]<br>
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*Process for cleaning sediment basins and conveyance systems of accumulated sediment
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*Removal of temporary erosion and sediment control BMPs
 +
*[https://www.pca.state.mn.us/sites/default/files/wq-strm2-07.pdf For residential construction]: plan to complete temporary erosion protection and downgradient perimeter control before the property is sold
 +
*[https://www.pca.state.mn.us/water/crop-production-npdessds-permitted-sites For construction on agricultural land: the land must be returned to its preconstruction use]
  
 
==Use of temporary sediment basins, if applicable==
 
==Use of temporary sediment basins, if applicable==
 
{| class="wikitable" style="float:right; margin-left: 10px; width:500px;"
 
{| class="wikitable" style="float:right; margin-left: 10px; width:500px;"
|-
+
|-style="border: 2px solid white"
 
! style="background: #d0e5f5" | Temporary sediment basin live storage:
 
! style="background: #d0e5f5" | Temporary sediment basin live storage:
|-
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|-style="border: 2px solid white"
 
| style="background: #f1f5fc" | If the live storage volume is calculated, it must accommodate a 2-year, 24 hour flood event, but cannot be less than 1,800 cubic ft
 
| style="background: #f1f5fc" | If the live storage volume is calculated, it must accommodate a 2-year, 24 hour flood event, but cannot be less than 1,800 cubic ft
|-
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|-style="border: 2px solid white"
 
| style="background: #E6F2FF" | If live storage is not calculated, then the basin must accommodate 3,600 cubic ft of live storage
 
| style="background: #E6F2FF" | If live storage is not calculated, then the basin must accommodate 3,600 cubic ft of live storage
 
|}
 
|}
*Use of temporary sediment basin if 10 or more acres of disturbed soil drain to one place, or 5 acres if the discharge point is within one mile of a special or impaired water<br>
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*Documented live storage volume from each acre drained<br>
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Sediment basins are used for to capture stormwater runoff from the site and allow sediment to settle prior to discharge. If the site is using a temporary sediment basin, the Construction Stormwater stormwater pollution prevention plan (SWPPP) must describe the following.
 +
*Use of temporary sediment basin if 10 or more acres of disturbed soil drain to one place, or 5 acres if the discharge point is within one mile of a special or impaired water
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*Documented [https://stormwater.pca.state.mn.us/index.php?title=Glossary#L live storage volume] from each acre drained
 
*Design that:
 
*Design that:
**prevents short-circuiting & floating debris discharge<br>
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**prevents short-circuiting and floating debris discharge
**allows for complete basin drawdown <br>
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**allows for complete basin [https://stormwater.pca.state.mn.us/index.php?title=Glossary#D drawdown]
**has a stabilized emergency overflow<br>
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**has a stabilized emergency overflow
**withdraws water from the surface<br>
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**withdraws water from the surface
**includes energy dissipation for the basin outlet<br>
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**includes [https://stormwater.pca.state.mn.us/index.php?title=Sediment_control_practices_-_Outlet_energy_dissipation energy dissipation for the basin outlet]
**is outside of surface waters <br>
+
**is outside of surface waters  
**avoids draining to wetlands<br>
+
**avoids draining to wetlands
**is operational before construction starts<br>
+
**is operational before construction starts
  
 
==Post-construction stormwater management==
 
==Post-construction stormwater management==
 
{| class="wikitable" style="float:right; margin-left: 10px; width:500px;"
 
{| class="wikitable" style="float:right; margin-left: 10px; width:500px;"
|-
+
|-style="border: 2px solid white"
 
! style="background: #d0e5f5" | Infiltration prohibitions and limitations:
 
! style="background: #d0e5f5" | Infiltration prohibitions and limitations:
|-
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|-style="border: 2px solid white"
| style="background: #f1f5fc" | Infiltration is prohibited where: industrial facilities cannot under an NPDES Industrial Stormwater permit, vehicle fueling/maintenance occurs, <br> there is less than 3 ft between the infiltration device and bedrock/seasonably saturated soils, and high levels of contaminants will be mobilized
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| style="background: #f1f5fc" | Infiltration is prohibited where: [https://stormwater.pca.state.mn.us/index.php?title=Stormwater_infiltration_at_permitted_industrial_stormwater_facilities industrial facilities cannot infiltrate under an NPDES Industrial Stormwater permit], vehicle fueling/maintenance occurs, there is [https://stormwater.pca.state.mn.us/index.php?title=Shallow_soils_and_shallow_depth_to_bedrock less than 3 ft between the infiltration device and bedrock]/[https://stormwater.pca.state.mn.us/index.php?title=Shallow_groundwater seasonably saturated soils], and [https://stormwater.pca.state.mn.us/index.php?title=Stormwater_infiltration_and_contaminated_soils_and_groundwater high levels of contaminants will be mobilized]
|-
+
|-style="border: 2px solid white"
| style="background: #E6F2FF" | Infiltration is limited within: clay soils, 1,000 ft upgradient or 100 ft downgradient of active karsts, a Drinking Water Supply Management Area, or <br> areas with infiltration rates of >8.3 inches/hour
+
| style="background: #E6F2FF" | Infiltration is limited within: clay soils, 1,000 ft upgradient or 100 ft downgradient of [[karst|active karst]], a [https://stormwater.pca.state.mn.us/index.php?title=Stormwater_and_wellhead_protection Drinking Water Supply Management Area], or areas with infiltration rates of >8.3 inches/hour
 
|}
 
|}
*Preference for [https://stormwater.pca.state.mn.us/index.php?title=Green_Infrastructure_for_stormwater_management| Green Infrastructure] techniques <br>
+
 
*No net increase (new development) or net decrease (redevelopment) in:<br>
+
Permanent stormwater management systems, like [https://stormwater.pca.state.mn.us/index.php?title=Stormwater_infiltration_Best_Management_Practices infiltration basins], vegetated filter strips, [https://stormwater.pca.state.mn.us/index.php?title=Stormwater_ponds stormwater ponds], must be designed, constructed, and maintained correctly in order to function properly. Construction Stormwater stormwater pollution prevention plans (SWPPPs) must describe these systems and design them to meet the following permit requirements.
**stormwater discharge volume, <br>
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*Preference for [https://stormwater.pca.state.mn.us/index.php?title=Green_Stormwater_Infrastructure_(GSI)_and_sustainable_stormwater_management Green Infrastructure] techniques
**[https://stormwater.pca.state.mn.us/index.php?title=Total_Suspended_Solids_(TSS)_in_stormwater| total suspended solids], and<br>
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*No net increase (new development) or net decrease (redevelopment) in
**[https://stormwater.pca.state.mn.us/index.php?title=Phosphorus_in_stormwater| total phosphorus] <br>
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**stormwater discharge volume,  
*Reason infiltration is not allowed, if applicable, and alternative treatment system<br>
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**[https://stormwater.pca.state.mn.us/index.php?title=Total_Suspended_Solids_(TSS)_in_stormwater total suspended solids], and
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**[https://stormwater.pca.state.mn.us/index.php?title=Phosphorus_in_stormwater total phosphorus].
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*Provide the reason infiltration is not allowed, if applicable, and describe the alternative treatment system. See the [https://stormwater.pca.state.mn.us/index.php?title=Stormwater_infiltration section on infiltration constraints here].
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[[Category:Level 3 - Regulatory/Municipal (MS4)/Guidance, outreach materials, miscellaneous information]]
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[[Category:Level 2 - Regulatory/Municipal (MS4)]]

Latest revision as of 16:11, 31 January 2023

construction stormwater image</alt>

The Municipal Separate Storm Sewer System (MS4) [MS4 Staff Site Plan Review Guidance permit requires the permittee to conduct site plan reviews]. Permittees must perform and document site plan reviews for construction projects that disturb one acre or more of land. The site plan review ensures active and post-construction requirements of a permittee's regulatory mechanism (e.g. code, ordinance, law) are met. The MS4 Permit requires the regulatory mechanism to be as stringent as the MNR100001/Construction Stormwater Permit.

This permit requirement is somewhat vague and has led to people not realizing that they need to review plans for specific items. The items identified below are the minimum that must be evaluated during a stormwater site plan review under the MS4 and Construction Stormwater Permits. For each site plan review performed, permittees must document the project name, location, total acreage to be disturbed, owner and operator of the proposed construction activity, and any stormwater related comments used to approve or deny the project. If you’d like to conduct a more comprehensive review, please see the MPCA’s Stormwater Pollution Protection Plan (SWPPP) Checklist. During the site plan review, you must verify that site plans include the information listed on this page.

Here's a PDF version of this page

Warning: The permittee’s Regulatory Mechanism(s) shall require that owners and operators of construction activity develop site plans that must be submitted to the permittee for review and approval, prior to the start of construction activity. Site plans must be kept up-to-date by the owners and operators of construction activity with regard to stormwater runoff controls. The Regulatory Mechanism(s) must require that site plans incorporate the following erosion and sediment controls and waste controls as described in the above referenced permit:

(1) BMPs to minimize erosion
(2) BMPs to minimize the discharge of sediment and other pollutants
(3) BMPs for dewatering activities
(4) Site inspections and records of rainfall events
(5) BMP maintenance
(6) Management of solid and hazardous wastes on each project site
(7) Final stabilization upon the completion of construction activity, including the use of perennial vegetative cover on all exposed soils or other equivalent means
(8) Criteria for the use of temporary sediment basins

The program shall include written procedures for site plan reviews conducted by the permittee prior to the start of construction activity, to ensure compliance with requirements of the Regulatory Mechanism(s). The site plan review procedure shall include notification to owners and operators proposing construction activity of the need to apply for and obtain coverage under the Agency’s general permit to Discharge Stormwater Associated with Construction Activity No.MN R100001.

Best Management Practices (BMPs) to minimize erosion

Stabilization schedule must be no less than:
14 days for all exposed soils
7 days if a discharge point is within one mile of a special or impaired water
24 hours for areas within 200 ft of a public water during fish spawning times
24 hours for areas of ditches and swales within 200 ft of the property edge or surface water discharge point and 14 days for remainder
mulch stabilized slope
Example of properly stabilized site.

BMPs to minimize erosion are the first line of defense for protecting stormwater from sediment running off your site. Soil without proper erosion control, such as blanket, mulch, or vegetation is prone to erosion. When reviewing site plans, ensure effective erosion control methods are described and located in the appropriate areas.


For more information on site stabilization see this page.

BMPs to minimize the discharge of sediment and other pollutants

photo silt fence
Photo of a well-constructed silt fence, which is a perimeter control practice.

Properly installed and maintained sediment control BMPs, such as silt fence or bioroll, prevent sediment from discharging from your site. They allow stormwater to pass through, but filter out sediment. When reviewing site plans, ensure that sediment controls to be used will be effective for the scale of the site.

Site inspections and rainfall records

Insepction schedule must be no less than:
Every 7 days during active construction
Within 24 hours after a 0.5 inch rain event
If work is suspended due to frozen ground, inspections must begin within 24 hours after runoff occurs or construction starts
For parts of the site with permanent cover but work is ongoing elsewhere, inspections can be once per month
If the entire site has permanaent cover and there is no active construction, inspections can be once per month for twelve months

Site inspections must be conducted by a trained person every seven days and within 24 hours of a rainfall event equal to or greater than 1/2 inch. The Construction Stormwater stormwater pollution prevention plan (SWPPP) should document the person responsible for site inspections and any modified inspection frequency.

  • Schedule for inspecting and recording inspections
  • Documentation of inspections, including:
    • date and time of inspection
    • inspector name
    • inspection findings and corrective actions
    • recent rainfall events of 0.5 inches in 24 hours
    • observed discharge and discharge points
    • proposed amendments to the site plan

See here for MPCA's construction stormwater inspection checklist

BMPs for dewatering activities

When done correctly, dewatering activities will only discharge clear water. Therefore, when applicable, Construction Stormwater stormwater pollution prevention plans (SWPPPs) should include the following.

  • A plan to discharge sediment-laden water to a sedimentation basin
  • A plan for dewatering to prevent discharge of sediment laden water, erosion, and downstream impacts

BMP maintenance

BMP maintenance schedule must be no less than:
End of next business day for nonfunctioning BMPs
End of next business day or as soon as conditions allow for nonfunctioning perimeter control
72 hours or as soon as conditions allow for draining sedimentation basins
24 hours for tracked sediment
7 days for removing deltas and sediment from surface water and restabiliztion

Sediment control devices are only effective if properly maintained. Ensure Construction Stormwater stormwater pollution prevention plans (SWPPPs) note the following schedules and procedures.

  • Schedule and procedure to repair and replace adjusted and non-functioning BMPs or perimeter control devices when sediment reaches ½ the device height
  • Schedule to inspect surface waters and streets
  • Schedule and procedure to maintain sediment basins
  • Procedure to remove tracked sediment
  • Schedule to inspect infiltration areas

For information on specific construction BMPs go to the Inspection and maintenance section for individual Erosion prevention practices or Sediment control practices.

Management of solid and hazardous waste

Washout operations specifications:
Washout wastes must not contact the ground
Washout operations must not result in runoff

Properly storing, handling, and disposing of chemicals and building materials protects stormwater. Construction Stormwater stormwater pollution prevention plans (SWPPPs) must include methods to prevent chemicals from coming in contact with stormwater.

  • Cover on building products, pesticides, herbicides, insecticides, fertilizers, chemicals, and landscape materials
  • Plan for properly storing and disposing of waste
  • Securing portable toilets
  • Process for containing washout wastes
  • Defined limited area for vehicle washing, fueling, and maintenance and a plan to contain washing runoff
  • Prohibition of engine degreasing onsite

For more information link here.

Final stabilization when construction is complete

Infiltration practice complete with trees
Infiltration practice following site closure, complete with trees.

Final stabilization will provide long-term protection from sediment loss. Construction Stormwater stormwater pollution prevention plan (SWPPPs) must provide a final stabilzation plan.

Use of temporary sediment basins, if applicable

Temporary sediment basin live storage:
If the live storage volume is calculated, it must accommodate a 2-year, 24 hour flood event, but cannot be less than 1,800 cubic ft
If live storage is not calculated, then the basin must accommodate 3,600 cubic ft of live storage

Sediment basins are used for to capture stormwater runoff from the site and allow sediment to settle prior to discharge. If the site is using a temporary sediment basin, the Construction Stormwater stormwater pollution prevention plan (SWPPP) must describe the following.

  • Use of temporary sediment basin if 10 or more acres of disturbed soil drain to one place, or 5 acres if the discharge point is within one mile of a special or impaired water
  • Documented live storage volume from each acre drained
  • Design that:
    • prevents short-circuiting and floating debris discharge
    • allows for complete basin drawdown
    • has a stabilized emergency overflow
    • withdraws water from the surface
    • includes energy dissipation for the basin outlet
    • is outside of surface waters
    • avoids draining to wetlands
    • is operational before construction starts

Post-construction stormwater management

Infiltration prohibitions and limitations:
Infiltration is prohibited where: industrial facilities cannot infiltrate under an NPDES Industrial Stormwater permit, vehicle fueling/maintenance occurs, there is less than 3 ft between the infiltration device and bedrock/seasonably saturated soils, and high levels of contaminants will be mobilized
Infiltration is limited within: clay soils, 1,000 ft upgradient or 100 ft downgradient of active karst, a Drinking Water Supply Management Area, or areas with infiltration rates of >8.3 inches/hour

Permanent stormwater management systems, like infiltration basins, vegetated filter strips, stormwater ponds, must be designed, constructed, and maintained correctly in order to function properly. Construction Stormwater stormwater pollution prevention plans (SWPPPs) must describe these systems and design them to meet the following permit requirements.

This page was last edited on 31 January 2023, at 16:11.