Minnesota Department of Transportation

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Project development

Environmental process | Environmental review

Erosion and Construction Stormwater Management

Purpose

The purpose of this erosion control information is to help design projects that will minimize erosion, effectively manage stormwater, and establish functional roadside vegetation during construction. The Erosion and Stormwater Management Unit provides consultation on Stormwater Pollution Prevention Plans (SWPPP), erosion control plans, vegetation plans, stormwater treatment plans, compliance with construction stormwater regulations, construction stormwater permitting, and overall environmental constructability. 

When to use this subject

Coordinate with the Erosion and Stormwater Management Unit for projects that will contain any of the following conditions or work types:

  • Work near, over, or in surface waters such as rivers, streams, lakes or wetlands
  • Steep slopes or highly erosive soils
  • Urban reconstruction
  • Full depth reclamation
  • Overlapping environmental concerns, especially when there is limited space for construction
  • Construction of one acre or more of new impervious area
  • Ten or more acres of soil disturbance

All projects that disturb at least one acre of soil are required to apply for a Construction Stormwater (CSW) Permit from the Minnesota Pollution Control Agency (MPCA). Smaller projects also require a permit if they are part of a larger project, such as one of multiple work packages. The Erosion and Stormwater Management Unit website includes a CSW Permit Application Worksheet.

Projects located on tribal lands that disturb at least one acre of land are required to apply for a CSW permit from the United States Environmental Protection Agency (EPA). MnDOT maintains a map showing Indian Country in Minnesota.

Projects that disturb at least 50 acres of soil and are within a mile of a special or impaired water are required to have MPCA review their SWPPP. The MPCA requires 30 days for this review period, but MnDOT projects are usually sent at approximately the 30-percent plan stage, depending on complexity. Review at this early stage is focused on the capacity for permanent stormwater treatment of runoff from new impervious surfaces. Contact Linnea Savereide or Todd Smith to coordinate SWPPP review.

Projects that disturb less than one acre of soil may be required to apply for a CSW permit if they are associated with another project and the two projects cumulatively disturb at least one acre of soil. More information about this can be found in the MPCA’s common plan of development fact sheet.

How this subject fits into the overall project development process

For projects in Greater Minnesota Districts:

Begin coordination with the Erosion and Stormwater Management Unit during the P6 Baseline Scheduling with the Office of Environmental Stewardship and continue through the Early Notification Memo. Depending on the characteristics of each project, the ESM Unit will participate in plan review during the 30-percent, 60-percent, and 90-percent plan review stages. Of particular concern are the projects that contain the conditions or work types described in the previous section, titled When to Use This Subject.

For projects in the Metro District:

Metro District’s Water Resources Engineering and Final Design staff each design different aspects of the SWPPP, erosion control, and vegetation plans. Water Resources design squads conduct final review of these elements. A key contact for these issues is the MS4 Engineer Jason Swenson, shown in the Contacts section.

For all projects:

District hydraulics, design, and/or environmental coordinator staff prepare and review the SWPPP and coordinate CSW Permit application. CSW permit application begins at 90-percent plan for most projects, and at 30-percent plan when MPCA is required to review the SWPPP (projects that disturb at least 50 acres of soil and are within one mile of a special or impaired water). Information on the CSW Permit application process is available on the Erosion and Stormwater Management web page.

Permanent stormwater requirements

There is significant overlap between permanent stormwater treatment and the stormwater management required on construction projects. The EPA. MPCA, and local watershed districts dictate permanent stormwater requirements. Technical support for permanent stormwater compliance and design is provided by the OES Environmental Assessment Unit and the Bridge Office Hydraulics Unit. Design is done by District hydraulics engineers. The CSW Permit and Municipal Separate Storm Sewer System (MS4) Permit dictate stormwater management during construction. The OES Erosion and Stormwater Management Unit provides technical support for design and implementation of these temporary measures as well as the process of building the green infrastructure components of permanent stormwater treatment facilities.

Other environmental impacts and regulations

The methods and practices that prevent erosion and control sediment are also involved in the avoidance and mitigation of many other environmental impacts. Coordinate with the ESM Unit (in addition to the subject matter expert for the other environmental issues) on projects that have multiple or overlapping environmental concerns, especially if there is limited space for construction activity.

Right of Way

Having adequate working space is critical to any construction project and affects a project’s environmental impacts. Planning for adequate right of way is needed to avoid erosion and stormwater management problems such as highly erosive slopes, encroachment into areas of environmental sensitivity, and lack of space for stormwater treatment, staging, and stockpile storage.

Organizations involved

  • MnDOT:
  • MPCA: Issues Construction Stormwater Permit to regulate construction activity and protect surface waters from sedimentation and other forms of pollution generated by construction activity
  • United States EPA: Issues Construction Stormwater Permit for work taking place on tribal land
  • Minnesota Department of Natural Resources (MnDNR): Issues work permit for any work in public waters
    • Requirements and best management practices of this permit include interactions and overlap with some CSW permit requirements
  • Local Watershed Districts:
    • Issue permits for work in a watershed district boundary
    • Aimed at protecting water quality, may differ from CSW Permit requirements