Winter 2022

• Construction stormwater inspectors identify top 5 violations in 2021
• Remember to do winter inspections!
• City of Apple Valley MS4 training videos
• MN Stormwater Manual updates
• Apply to be a Minnesota GreenCorps host site
• Events

Construction stormwater inspectors identify top 5 violations in 2021

Construction stormwater inspectors tallied what violations of the NPDES/SDS General Construction Stormwater permit were most prevalent over the past year based on their inspections. Inspectors hope to use this information to determine where efforts should be focused in the education of permittees.

Inspections: The most common violation was failure to have a trained person conduct and record weekly and 1/2 inch rainfall inspections. Permittees must ensure a trained person will inspect the entire construction site at least once every 7 days during active construction and within 24 hours after a rainfall event greater than 1/2 inch in 24 hours. Failure to conduct the inspections means that sediment discharging off site would not be reported and corrected. The inspection records are important for communicating what items need to be addressed so can be corrected in a timely manner.

Downgradient Sediment Control BMPs: Permittees must install sediment control BMPs on all downgradient perimeters of the site and downgradient areas of the site that drain to any surface water, including curb and gutter systems. Sediment control BMPs (silt fences, biologs, etc.) must be installed prior to any land-disturbance and must not be removed until permanent cover is reached on site. These BMPs, if installed correctly, help stop mobile sediment from leaving the site.

Stabilization: The next two most common violations concern soil stabilization. For sites within one aerial mile and drain to a special or impaired water, soil stabilization must be initiated immediately and completed within 7 days when construction activity has permanently or temporarily ceased on any portion of the site. Item 8.4 applies to construction sites that are not within one mile of special or impaired waters. For these sites, stabilization must be initiated immediately when construction activity has permanently or temporarily ceased on any portion of the site and must be completed within 14 days. Inactively worked soil stockpiles must be stabilized within the same timelines.  

Redundant Sediment Controls: The last of the most common violations was the failure to provide redundant (double) perimeter sediment control BMPs for soil disturbances near surface waters. Permittees are required to provide redundant rows of down gradient sediment BMPs when:

• preservation of 50 feet of an existing buffer to a surface water is infeasible, 
• earth disturbance occurs within 50 feet of the surface water, and
• stormwater flows to the surface water (excluding road ditches, judicial ditches, county ditches, stormwater conveyance channels, storm drain inlets, and sediment basins).

Permittees must install the redundant sediment controls at least 5 feet apart unless limited by lack of available space. The CSW unit hopes that by understanding the top violations, and how to correct them, we can achieve greater compliance going forward into the 2022 construction season. If you have specific questions related to these violations, or questions about any part of the permit please reach out to the inspector assigned to the county your project is in.

Remember to do winter inspections!

Despite the extreme cold we've had this winter, Minnesota is experiencing intermittent thawing and even rain that can cause potential runoff events at construction sites. These events are increasing as winters in Minnesota continue to warm due to climate change. Runoff in winter months is exacerbated by to the inability of frozen ground to absorb any of the runoff. As long as construction activity is inactive during frozen conditions, inspections can  be suspended. However, inspections must be conducted within 24 hours of runoff occurring, including during inactivity. If construction activity resumes at the site during winter months or at any time, weekly inspections must also resume. Failure to have the BMPs installed, including stabilizing soils prior to leaving the site idle during winter months, is a violation of the permit. When conducting winter inspections, ensure there is adequate temporary cover on exposed soils to prevent erosion during runoff events and that downgradient sediment controls and inlet protection BMPs are installed and functioning properly. If not, repair or supplement the BMPs using methods appropriate for frozen conditions. For ideas, check out the Minnesota Stormwater Manual for recommended BMP practices in winter.

City of Apple Valley MS4 training videos

The City of Apple Valley created training videos for their Public Works staff on MS4 requirements and best practices since they were unable to meet in-person due to COVID-19. The training includes topics on illicit discharges, pollutant load reduction, vegetation management, construction site BMP management, chloride reduction and more. The City hopes to make it more public facing in the future.

MN Stormwater Manual updates

The MPCA is currently working on updates to the Minnesota Stormwater Manual. The updates include the following: 

• phosphorus and TSS credits for manufactured treatment devices,
• case studies for street sweeping,
• work on iron enhanced sand filters,
• planning guidance for incorporating green infrastructure into new development and redevelopment,
• site considerations for vegetation,
• guidance on snow storage,
• more outreach for the street sweeping phosphorus credit, and
• an article on managing runoff having elevated chloride concentrations.

Apply to be a Minnesota GreenCorps host site

The Minnesota Pollution Control Agency (MPCA) is accepting applications from organizations interested in hosting a Minnesota GreenCorps member for the 2022-2023 program year. Members serve at organizations throughout the state, completing community-focused environmental projects while gaining experience and learning valuable job skillsThe Minnesota Pollution Control Agency (MPCA) is accepting applications from organizations interested in hosting a Minnesota GreenCorps member for the 2022-2023 program year. Members serve at organizations throughout the state, completing community-focused environmental projects while gaining experience and learning valuable job skills.

The MPCA plans to place up to 46 full-time members with host site organizations. Organizations eligible to host include public entities (local, regional, state, and tribal), school districts, public education institutions, and nonprofits. Host sites provide day-to-day supervision and support Minnesota GreenCorps members on community-focused projects in one of four focus areas, including green infrastructure improvements and community forestry.

Projects may focus on green stormwater infrastructure activities such as:

• Inventorying and assessing existing stormwater best management practices.
• Identifying opportunities and implementing green infrastructure practices, such as rain gardens, permeable pavement, bioswales, green roofs, etc.
• Mobilizing volunteers to improve public lands.
• Quantifying the benefits of green infrastructure practices.
• Identifying chloride management strategies and providing guidance on proper salt application.
• Providing education about the benefits of stormwater practices and pollution prevention.
• Conducting surveys to measure participant knowledge gains and behavior change.

Applications are due by 5:00 pm on Tuesday, March 22, 2022. For more information and to apply to be a host site, visit https://www.pca.state.mn.us/waste/mn-greencorps-host-sites. Please direct questions to mngreencorps.pca@state.mn.us.

Build organizational capacity, advance environmental projects in your community, and help train the next generation of environmental professionals by hosting a Minnesota GreenCorps member!

Events

The University of Minnesota is offering a workshop on use of P8 Urban Catchment Model via Zoom on March 2^nd and 3^rd, with a short session on February 23 to confirm software installation and access. P8 is a water quality model for simulating pollutant generation and treatment in urban areas. This course will include presentations and hands-on exercises that will introduce you to the Windows version of the P8 model. The course will cover model assumptions, limitations, and application. You will also learn how to review the results of water quality models such as P8. 

Newsletter contact

If you have questions about or suggestions for this newsletter, contact Roberta Getman, MPCA-Rochester, 507-206-2629.