July 2017

• MS4 program highlight: Cottage Grove
• Pond, wetland, and lake inventory now available
• New! Stormwater sediment removal guidance
• New MIDS calculator training coming
• Construction stormwater: Common violations
• Stormwater research updates
• Industrial stormwater training
• New in the Minnesota Stormwater Manual
• Has your MPCA MS4 contact person changed?

MS4 program highlight: Cottage Grove

The City of Cottage Grove’s innovative stormwater pollution prevention program (SWPPP) is effectively reducing the impacts of stormwater on the community and city's surface waters. City staff answered our questions about how their program successfully manages stormwater. Q: What makes your SWPPP implementation unique? A: The Cottage Grove MS4 program is overseen by the city engineering division, which is part of the Community Development Department. Being part of Community Development, engineering is able to work closely with the planning division early on during the planning process of new development and re-development projects. Engineering is also able to work closely with the building division during the construction process. Having the support of the various divisions is key to implementing construction and post-construction stormwater requirements. Q: How do these connections play out in the program? A: During the planning process, specific construction and post-construction stormwater management requirements for each project can be identified early on, and included in the conditions of approval. Plan review is then completed in conjunction with the building division, with permits not being issued until all stormwater management requirements are met. Finally, the building division provides support during the construction process regarding construction stormwater requirements. The building official is copied on all erosion control inspection reports, and if controls are non-compliant, building inspections can be halted to ensure compliance is met. Q: Tell us about your partnerships with external parties and how they help you meet permit requirements. A: The City of Cottage Grove partners with the South Washington Watershed District to complete erosion and sediment control inspections on all private construction projects in the city. Utilizing this process helps to ensure specific city and watershed requirements are being met, along with the construction stormwater permit requirements. The watershed district also provides grant funding for post-construction stormwater BMPs that go above and beyond the minimum requirements. By providing this funding, projects in the city are able to install enhanced post-construction stormwater BMPs that provide a greater level of treatment than what would typically be achieved.  Q: What's your biggest obstacle to complying with MS4 requirements, and how did you overcome it? A: One of the biggest challenges the city has seen is working with private entities on maintenance of post-construction stormwater BMPs. To help manage this issue, a stormwater management agreement was drafted that is executed between the city and owner of all private BMPs. This agreement requires specific inspection and maintenance criteria be met, and gives the city the right to perform this work if necessary and assess the owner. These agreements are also recorded and [transferred] to the new owner in the event of a sale. Q: How can other MS4s apply your ideas to their communities to further stormwater protection across the state? A: One of the most important aspects of having an effective MS4 program is ensuring that other departments in the organization have an understanding of what the program is and why it is important. By having this support, each department is able to better do their part in achieving various requirements throughout the planning, construction, and operation process. Whether it is the planning division engaging engineering early on to determine a development’s stormwater management requirements, a public works employee identifying a private BMP maintenance issue, a building inspector addressing a silt fence issue, or code enforcement finding an illicit discharge, this is a key factor in managing an effective MS4 program.

Pond, wetland, and lake inventory now available

All 232 regulated MS4s were required to submit an inventory of all ponds, wetlands, and lakes (public and private) that collect stormwater within their jurisdiction. Permittees identified the type of waterbody, its unique ID number (assigned by the permittee), and its geographic coordinates in decimal degrees. The inventories have been combined into one spreadsheet in the Minnesota Stormwater Manual. The Minnesota Session Laws of 2009 require the MPCA to incorporate requirements for inventorying ponds, wetlands, and lakes into the MS4 general permit reissued in 2013. The law's intent was to quantify the bodies of water in each regulated MS4 with the potential for contamination by polycyclic aromatic hydrocarbons (PAHs) from the use of coal tar sealants.

New! Stormwater sediment removal guidance

The MPCA recently published updated guidance on managing sediment removal from stormwater collection and conveyance systems. Changes since June 2015 include:

• Revision of land use category definitions
  
• In the stormwater sediment spreadsheet, it's easier to calculate benzo[a]pyrene (B[a]P) equivalents and compare contaminant concentrations in stormwater sediment to soil reference values
  
• Sediment sampling is now required regardless of the volume of sediment to be excavated
• Minor changes to the section called “Determination of excavated soil as regulated solid waste”
• General information about hydraulic dredging added

This new publication is available on the MPCA web site. Additional information on coal tar sealants and managing stormwater sediment can be found in the Minnesota Stormwater Manual.

New MIDS calculator training coming

The MPCA is developing several training videos on the use of the MIDS calculator, some of which should be available in August. See the list of proposed video topics in the Minnesota Stormwater Manual.

The MIDS calculator has been downloaded more than 1,600 times this year. We would like to know if and how you are using the calculator; please contact Anne Gelbmann or Mike Trojan to let us know.

Construction stormwater: Common violations

MPCA construction stormwater inspectors are busy at construction sites checking on compliance with the Construction Stormwater General Permit. The use of down gradient sediment controls, such as silt fence, is common at construction sites. But all too often, inspection staff find that sites are not using erosion prevention BMPs properly. In particular, they are not being installed when earth disturbance has temporarily stopped on portions of the site.

Permittees are required to install a temporary soil stabilization BMP (i.e. mulch, hydromulch, plastic sheeting, or other cover) on portions of the site not worked on for 14 days or more. This includes inactively worked soil piles or any unworked exposed soils surrounding the active work area. While silt fence is important for helping to capture sediment that has dislodged from the site, erosion prevention BMPs prevent soil from moving in the first place, so they more effectively prevent sediment from leaving the site. Both erosion prevention and sediment control BMPs must be used during construction.

If portions of the construction site discharge stormwater to a special or impaired water located within one mile of the site’s boundary, then the timeline for stabilizing these soils drops to seven days. Permittees are required to immediately stabilize soils once it's known these areas will remain unworked for 14 or 7 days, as applicable.

For more information on erosion prevention practices, visit the Minnesota Stormwater Manual.

Stormwater research updates

In 2017, two large research projects are in full swing:

Infiltration in roadside swales: Long-term field testing — The MPCA and MnDOT have identified four new sites for this project, which will bring the total linear length of field sites to approximately a mile. This full-scale infiltration performance assessment uses water budgets derived from natural runoff events over annual periods to follow up on recent swale research conducted by University of Minnesota. Equipment will be installed this summer, with monitoring likely through 2018.

Underground infiltration monitoring – The MPCA and Capitol Region Watershed District have partnered to monitor two underground practices: one near Upper Villa Park (Roseville), and one at the Midway Stadium Business Center (St. Paul). Influent and subsurface sampling points and equipment are installed at both sites. This will allow assessment of pollutant loading, transport, and removal in these infiltration BMPs and the unsaturated zones beneath them. The research is looking at conventional stormwater constituents as well as sVOCs, VOCs, and other chemicals. Sampling for this project will continue through 2018.

For more detailed information on these and other projects, visit the Minnesota Stormwater Manual. Please contact David Fairbairn with any questions or input.

Industrial stormwater training

Mark your calendars for the next industrial stormwater training session this fall. The next University of Minnesota permit-overview workshop will be on Wednesday, September 6, at the MNDOT Training Facility in Arden Hills. This day-long session will cover permit basics, SWPP development and implementation, and stormwater monitoring and reporting requirements. For additional information or to register, visit the U of M Erosion and Stormwater Management Certification Program's web site.

New in the Minnesota Stormwater Manual

New pages were recently added to the manual:

• Design, construction, operation and maintenance specifications for pretreatment vegetated filter strips
• Stormwater infiltration at permitted industrial stormwater facilities
• Using the Minnesota Stormwater Manual and MIDS Calculator to help meet industrial stormwater permit requirements
• When infiltration is not authorized under a stormwater permit
• Phosphorus in stormwater
• MS4 pollution prevention fact sheets

 What’s in the works?

Check out some of the updates planned for Stormwater Manual:

• Green Infrastructure for stormwater management – links to green infrastructure resources
• Stormwater Program for Municipal Separate Storm Sewer Systems (MS4) – links to municipal stormwater management resources
  
• New work orders planned for summer 2017
• Updates to the swales section
  
• Information on design, construction, and maintenance of pretreatment settling practices; addition of pretreatment case studies and information on level spreaders
• New information for several construction stormwater best management practices

Find more detailed information on the Future Updates page in the manual.

Has your MPCA MS4 contact person changed?

Changes at the MPCA have resulted in new staff assignments for regulated MS4s. Visit the Stormwater Manual's MS4 page to find your MPCA staff contact.

The MS4 page has also gotten a facelift. We are adding additional guidance documents and tools in the next few months to help build and manage an effective MS4 program.

Newsletter contact

If you have questions about or suggestions for this newsletter, contact Anne Gelbmann, MPCA-St. Paul, 651-757-2384