April 2019 Vol. 7, No. 3

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Plan for flood emergencies

emergency flood plan

A guidebook from the St. Paul District of the US Army Corps of Engineers provides step-by-step instructions to help communities develop a flood emergency action plan. The template in the guidebook can be customized to fit each community’s or tribe’s situation.

The guidebook identifies critical items that should be completed. Topics include mutual aid agreements, personnel (including public works), and communications. Case studies, fillable forms, and links to additional resources are also provided.

An evacuation chapter recommends verifying that evacuation routes will not interfere with construction traffic. The chapter also includes information about the National Weather Service (NWS) campaign called “Turn Around, Don’t Drown.” Materials for educating the public and recommended signage are available on the NWS website. According to the site, 6 inches of water can make a car unstable or stall, and 12 inches can make a car float.

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Minimize slope erosion from flooding

slope stabilization guide

Recent projects funded by the Minnesota Local Road Research Board have looked at ways to control erosion on roadway slopes. One project focused on damage from roadway overtopping—when floodwaters flow across roads. Another project developed a matrix of erosion-protection measures for common site types.

Researchers from the U of M’s St. Anthony Falls Laboratory investigated the effectiveness of slope protection techniques to shield overtopped roadways and their downstream embankments from scour and erosion. Their conclusions included:

  • Bare soil with no vegetative cover (the control) is highly susceptible to erosion and is the worst-case scenario. New installations should have established vegetation before the first overtopping event is expected.
  • The three erosion protection techniques investigated—armored sod hydraulic soil stabilization, turf reinforcement mat, and flexible concrete geogrid mat—all encourage vegetation to grow through a mat, helping to stabilize the soil and protect the embankment from scour and erosion. Flexible concrete geogrid mat provided the best protection.

The project developed a matrix of erosion-protection measures that are less elaborate and more cost-effective than hiring contractors.

In the other project, University of Minnesota Duluth researchers determined effective methods for stabilizing slopes along Minnesota’s locally maintained roads and created a guide recommending slope stabilization methods. The guide presents eight different slope failure scenarios and recommends solutions to repair the failure. The goal is to allow local agency engineers to repair slopes without the help of outside geotechnical engineers.

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Manage snowmelt and runoff

climate management

Springtime in Minnesota: from blizzards to snowmelt and runoff, all in a matter of weeks or days. Materials are available to help transportation agencies manage snow disposal, snowmelt, and stormwater runoff, aiming to keep contaminants out of our waters.

The Minnesota Stormwater Manual, a wiki developed by the Minnesota Pollution Control Agency, has information about meltwater management and snow management plan guidelines. One section—Cold Climate Impact on Runoff Management—presents principles for adapting best management practices (BMPs) to provide effective pollutant removal and runoff control during cold-weather months. The site notes that runoff from snowmelt has special characteristics, and BMP design criteria addressing only rainfall runoff might not work well during cold periods.

The Transportation Association of Canada has a synthesis about snow disposal: Syntheses of Best Practices - Road Salt Management (2013): 8.0 — Snow Storage and Disposal. This synthesis establishes guiding principles to aid in developing appropriate snow removal, storage, and disposal procedures. It also provides an approach to locating, designing, and managing snow disposal facilities in a way that minimizes the potential impacts of contaminated snow and salt-laden meltwater on the surrounding environment.

An article in Stormwater, the journal for surface water quality professionals, takes a look at “Where Old Snow Goes to Melt” (Jan./Feb. 2017). The article shares examples of snow disposal practices in South Dakota, Minnesota, Massachusetts, and New Jersey. For example, the Massachusetts Department of Environmental Protection introduced a tool in 2015 to help municipalities choose sites for disposal of large volumes of snow.

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Choose the best pothole patch

pothole graph

More water, more freeze-thaw cycles, more cracks and potholes. A guide and accompanying how-to cards from the Minnesota Department of Transportation help road crews choose patching methods that match specific repair conditions.

Researchers from the University of Minnesota Duluth identified four repair methods best suited to Minnesota: cold mix, hot recycled asphalt, mastic material, and mill-and-fill with hot-mix asphalt. They also compiled best practice guidelines for patching method selection, placement, compaction practices, and moisture control to provide further guidance. Decision trees help road crews choose the most suitable method for each repair.

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Use new hydraulic modeling tools

EDC logo

Next-generation hydraulic tools improve the understanding of complex interactions between river or coastal environments and transportation assets. Collaborative hydraulics is one of the innovation areas in Every Day Counts round five (EDC-5).

Two-dimensional (2D) hydraulic modeling software, graphical interfaces, and supporting resources are now available. Recent advances in computer hardware, modeling software, Geographic Information Systems, and survey practices have made 2D modeling efficient, intuitive, and accessible to engineers and designers.

Because 2D models avoid many of the limiting assumptions required by 1D models, the results can significantly improve the ability of highway agencies to design safer, more cost-effective, and resilient structures on waterways.

In addition, the 3D visualization capabilities of these modeling tools aid in communicating design results and implications to a variety of stakeholders through intuitive and visually rich graphical output.

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Plant the idea for living snow fences

snow fence website

Snow fences reduce spring flooding by keeping soil sediment out of ditches to maintain proper drainage. Now might be the time to plant the idea with your local landowners to consider living snow fences.

The Blowing Snow Control Tools website has as an online tool to estimate the return on investment of living snow fences or standing corn rows on private lands. Webinars introduce the snow control cost-benefit tool and interpret the results from the landowner and agency perspectives.

The website also includes a design module that allows agencies to examine solutions to site-specific problems and then design a snow fence or plan road design techniques. The website is developed and maintained by the Center for Transportation Studies with sponsorship from MnDOT.

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