Category Archives: Environment

Collaboration with Minnesota Zoo aims to conserve wildlife

Turtles and other wildlife are at risk along Minnesota roadways.

MnDOT is collaborating with the Minnesota Zoo on a new research project installing small animal exclusion fencing. The fencing is intended to redirect turtles (and other small animals) to culverts and bridges where they can cross the road safely.

Blanding’s and wood turtles are listed as threatened species by the Minnesota Department of Natural Resources.

A proactive approach to wildlife conservation will hopefully reduce small animal-vehicle collisions and prevent these species from becoming listed under the federal Endangered Species Act.

Reducing small animal collisions also improves driver safety. Hitting (or trying to avoid) a turtle on the road can cause significant damage and injuries to motorcyclists and bicyclists. It can also be unsafe for drivers to attempt to pull over and assist small animals across the road—especially in high-traffic areas.

Exclusion fences were installed along four Minnesota roadways this past year (Waconia, Highway 5, Scandia, Highways 97 and 7, Eagan, Highway 2) and will be evaluated over the next year.

The research project started in Sept. 2017 and is estimated to be completed in June 2021. The end goal is to develop a standard set of designs and recommendations for future installation along other Minnesota highways. Christopher Smith, MnDOT’s wildlife ecologist is the technical liaison leading this project.

Visit the MnDOT Office of Research & Innovation for project updates.

Investigating Wastewater Reuse at Rest Areas and Truck Stations

Researchers have provided MnDOT with a comprehensive and practical evaluation of what the agency would need to do to develop wastewater reuse systems for its truck stations and rest areas. Two sites will install the research project’s recommended systems soon. 

Background

Despite Minnesota’s abundance of water resources, 75 percent of the state’s water comes from aquifers at increasingly unsustainable rates. The recycling of wastewater for other uses would allow potable groundwater aquifers to be used more conservatively. Gov. Tim Walz and former Gov. Mark Dayton issued executive orders directing state agencies to make efforts to save energy and water. Since every MnDOT building uses water, the potential for substantial water reuse exists.

MnDOT sought to learn the potential for on-site wastewater reuse as well as the barriers to implementing, operating and maintaining water reuse systems. Developing a system of water recycling at MnDOT facilities could create sustainable water resources for toilet flushing and vehicle washing.

“The great success of this project arises from its close examination and evaluation of all aspects of industrial wastewater reuse in Minnesota, from regulation to the practical choice of technology MnDOT will be able to sustain into the future,” said Sara Heger, research engineer, Water Resources Center, University of Minnesota.

To that end, MnDOT initiated this research project to evaluate when reuse would make sense from a regulatory, environmental, economic and management perspective at more than 50 rest areas and 137 truck-washing stations and storage facilities.  

What Was Our Goal?

The objective of this project was to investigate and evaluate the potential for wastewater reuse within MnDOT. As part of the project, researchers would identify regulatory challenges, properties of wastewater streams, contaminants that would be difficult to remove or manage, potential treatment technologies and the MnDOT processes that would be suitable candidates for wastewater reuse. In addition, researchers intended to examine the possibility of recapturing salt-laden wastewater for further use in winter road maintenance.

What Did We Do?

The project’s work progressed in three phases:

  • Review of current wastewater reuse policies and regulations in Minnesota, wastewater reuse programs in other states, as well as international guidelines for water reuse. Researchers reviewed case studies about successful wastewater reuse systems implemented in Minnesota and examined potential regulatory barriers to wastewater reuse implementation.
  • Sampling and data collection from 11 MnDOT truck-washing facilities to determine common contaminants. Samples were taken year-round from an equal number of facilities with holding tanks and from those served by city sewer systems. Researcher collected 37 winter samples. In addition, a nonwinter sample was collected from each site to compare the characteristics of winter versus nonwinter samples.
A MnDOT maintenance worker and a University of Minnesota employee take wastewater samples from a waste trap at a MnDOT truck-washing facility.
At truck facilities connected to city sewers, researchers took wastewater samples from flammable waste traps while trucks were washed.
  • Evaluation of existing wastewater treatment technologies to identify those meeting MnDOT’s needs. Researchers investigated methods that could most effectively remove the identified contaminants from the wastewater while allowing chlorides to remain for brine production. Researchers also determined cost estimates over an assumed 25-year life span.

What Did We Learn?

Policies and regulation. Minnesota’s current state and federal regulatory framework addressing wastewater reuse is dispersed over multiple agencies, and rules can be contradictory. Currently at least four agencies are involved in wastewater regulation. Wastewater reuse systems require a variance and in some cases additional permits from local agencies. Researchers reported that the regulatory framework for water reuse in Minnesota needs to be simplified and streamlined to create a more effective permitting process.

Researchers noted that California has been a pioneer in water reuse since 1929. Florida is a national leader, recycling more than 727 million gallons per day, while Arizona developed effective water reuse regulations in 1972 and has been a regulatory model for Texas, New Mexico and Montana. Investigators suggested that Minnesota could adopt water use standards modeled on Arizona’s as the state clarifies its regulatory framework.

In addition, researchers reviewed four case studies in which wastewater reuse systems were successfully implemented.

Wastewater sample data. Researchers tested samples for volatile organic compounds, metals, fecal coliform, mercury, suspended solids, biochemical oxygen demand (BOD) and chlorides. They found excessive levels of only one chemical, ethylene dichloride, which is commonly used as a solvent; MnDOT could reduce its use of it. Across all samples, the critical contaminants to be removed for water reuse were organics (BODs) and suspended solids. Excessive chlorides were not considered a contaminant since chloride-rich water could be reused as brine in winter road maintenance operations.

“This innovative study’s findings will result in the implementation of wastewater reuse technology at two MnDOT sites. The project promises to be a continuing success,” said Neile Reider, administrative engineer, MnDOT Office of Maintenance.

Recommended technology. Researchers recommended that MnDOT use either a recirculating sand filter or a membrane bioreactor to treat wastewater. An economic evaluation comparing long-term costs of the two technologies indicated that the membrane bioreactor is the most economical system for MnDOT.

What’s Next?

A pilot implementation is planned for the Granite Falls, Minnesota truck station, a facility that is already plumbed to separate and collect washdown water. Evaluation of the system’s treatment effectiveness and maintenance requirements will inform the broader scale implementation of wastewater reuse systems for MnDOT.

This post pertains to Report 2019-22, “Investigating Wastewater Reuse at MnDOT Truck Stations,” published May 2019. Visit the MnDOT project page for more information.

Using Regional Materials to Manage Stormwater Runoff

Researchers determined that natural soil amended with locally sourced materials performed well in bioslopes and bioswales. This practice will allow MnDOT to avoid hauling in costly commercial materials for stormwater management installations.

What Was the Need?

Following the requirements of the Minnesota Pollution Control Agency, MnDOT designs and constructs roadways with means to contain and manage the first inch of stormwater runoff—the “first flush”—flowing from impervious pavements. The agency often accomplishes this with low-impact development (LID) practices such as bioslopes and bioswales (shallow ditches) along roadways that mimic the original landscape. Constructed of tested soil mixtures and vegetation, bioslopes and bioswales effectively absorb runoff and filter sediment, heavy metals, chemicals and other pollutants that wash from the roads, preventing entry into the watershed.

In previous MnDOT highway construction projects, soils that are unsuitable for supporting pavements, such as peat and muck from wetlands, are dug out and hauled away as waste. Commercial compost mixtures are transported to the site for bioslope and bioswale construction. These hauling operations are expensive. To reduce costs, MnDOT has been investigating the use of natural materials close to construction sites and previously discarded as waste as possible filtration media in LID stormwater management.

A cross section drawing of an engineered bioslope design shows the edge of the pavement, a filter strip of grass at the top of the slope and the section of filter material with an underdrain surrounded by small rock buried beneath it. Blue arrows show the flow of water.
This cross section of a common engineered bioslope shows the position of a vegetation filter strip, a section of biofiltration material and an underdrain pipe beneath it. The blue arrows indicate the flow of water.

Phase I of this project examined the infiltration capabilities of compost mixtures and naturally abundant peat and muck in northeastern Minnesota as alternatives to commercial soil and sand in bioslopes and bioswales. Researchers conducted laboratory tests and constructed pilot plots, monitoring their performance. The current project continued the lab and field investigations, and developed a new peat-based biofilter based on research findings.

What Was Our Goal?

The primary objective of this project was to apply the results of the first phase of study to the design and construction of bioswales and bioslopes using local alternative media. An essential corollary objective was to determine whether lab tests and procedures could accurately predict and monitor the performance of these media in the field. Further, researchers sought to determine the effects of aging on alternative media performance.

What Did We Do?

The multidisciplinary research team addressed all aspects of alternative filter media suitability, from water retention and infiltration capacity, to contaminant-filtering effectiveness, to the ability to grow and support vegetation. First, researchers conducted a comprehensive literature review of bioslope and bioswale designs and methods of monitoring filtration media properties on-site. They examined best management practices, including state and federal regulations. Next, they collected treatment media from across Minnesota, including salvaged peat and muck, and commercial peat from an approved source. Researchers evaluated the media and determined potential filtration mixtures based on the results of the previous project and MnDOT standards.

“Lab and field investigations showed the salvage and reuse benefits of muck and other organic materials for slope and ditch topdressing to retain the first flush of rain from roadways,” said Dwayne Stenlund, erosion control specialist, MnDOT Office of Erosion Control and Stormwater Management.

In situ and lab materials from nine established and newly constructed biofilter sites were tested. These sites were constructed between 1990 and 2014, and the main soil filtration medium was amended with compost, peat or muck. On-site materials were evaluated for compaction, conductivity and absorption while lab samples were analyzed for metal and other contaminant retention.

Researchers also monitored six pilot test sites from Phase I. Three plots were prepared with native soil mixed 50/50 with compost and three plots with native soil mixed 50/50 with peat. Plots were examined and data were retrieved from instruments previously installed to measure rainfall, soil absorption and ambient temperature.

The team also established and monitored a new peat-based biofilter stormwater system using selected filter materials and designs. The new biofilter was installed throughout 5.7 miles of new road construction at Eagles Nest, which included extensive bioslopes and a bioswale enhanced with an underdrain system to resist silt clogging.

What Did We Learn?

Most sites showed deficiencies in nutrient and organic matter to support plant growth, and were dominated by weedy plants. Additional fertilizer and organic matter along with appropriate seeding could assure a good cover crop of grasses.

“This project’s results allow MnDOT to use in situ soil to build bioslopes and bioswales to retain the first inch of roadway runoff and associated pollutants. Using in situ materials rather than transporting new materials to the site will save taxpayer dollars, said” David Saftner, department head, University of Minnesota Duluth Department of Civil Engineering.

Compost and peat showed comparable effective water absorption and infiltration performance in amended biofilters. Lab tests can conservatively predict field performance. Researchers noted that early trends should be reinforced by further monitoring.

Peat’s performance shows it is a good alternative to compost for removing metals and phosphates in biofilters. It removes metals as well as compost and leaches less phosphate. Capacities to retain pollutants diminish with age for both media.

What’s Next?

Alternative local filtration media show great promise in stormwater management bio-installations. The next phase of this project will gather additional data from all plots to more fully assess the alternative media’s capabilities over time.

This post pertains to Report 2019-31, “Development and Regionalization of In Situ Bioslopes and Bioswales,” published July 2019. Visit the MnDOT project page for more information.

Evaluating Iron-Enhanced Swale Ditch Checks for Phosphorus Removal

Researchers documented performance of an iron-enhanced ditch check filter to remove phosphorus from stormwater over three years. The filter was effective, but its performance decreased over time, and it will require relatively frequent maintenance. Several design changes may be considered.

What Was the Need?

The Minnesota Pollution Control Agency (MPCA) requires that developments adding more than an acre of impervious land must try to include methods to infiltrate the first inch of stormwater runoff. This “first flush” of stormwater from impervious road pavement contains pollutants that could contaminate watersheds.

To meet its MPCA permit requirements, MnDOT might consider constructing strategically designed ditch blocks and swales: wide, shallow ditches with mounds of engineered soil and sand mixtures and vegetation along roadways that manage stormwater flow.

“Our success in removing phosphorus from stormwater runoff using iron particles in filtering ditch checks showed strong proof of concept. Modification of the filters’ orientation in the ditches could result in a device that is both more effective and low maintenance for MnDOT,” said John Gulliver, department head, University of Minnesota Department of Civil, Environmental and Geo-Engineering.

Previous research has shown that MnDOT’s linear swales are effective filters of contaminated highway runoff. That study also conducted laboratory investigations into enhanced ditch checks—low permeable mounds placed in a swale to reduce water velocity. Researchers tested the ability of various media in an experimental ditch check filter to remove more pollutants. A subsequent MPCA study examined the capability of an iron-enhanced sand trench to remove phosphorus.

In September 2014, MnDOT constructed two iron-enhanced ditch checks in a swale along CR15 (TH5) in Washington County to test two design versions. One failed to function effectively; the other was monitored for four months in 2015, showing effective phosphorus and metals retention.

What Was Our Goal?

The goals of this project were to investigate the long-term effectiveness of iron-enhanced ditch checks in retaining pollutants and to develop recommendations for maintenance actions needed to support effective filter performance.

What Did We Do?

Researchers monitored the performance of the CR15 (TH5) iron-enhanced ditch check from 2016 through 2018 while temperatures were above freezing. A tipping-bucket rain gauge was connected to a data logger to record rainfall at the site. Water samples were collected automatically through tubing at four points: the inflow and outflow of the check dam and filter insert. (Two monitoring wells had been built into the filter.) An automated sampling instrument was triggered by flow through the filter insert. The data logger recorded water levels, flow rate, cumulative flow volume and rainfall depth information continuously at five-minute intervals.

Near the end of the study, workers used a boring machine to take core samples of the ditch check and the filter insert.

Three workers in safety vests and hard hats stand near a tall boring machine taking a core sample of the ditch check filter.
Near the end of the study, workers used a boring machine to take core samples of the ditch check and the filter insert.

Pressure transducers installed inside the monitor wells measured upstream and downstream water levels at the filter insert section. Flow rate through the filter was calculated. Researchers retrieved inflow and outflow samples within 24 hours of the end of a rain event. The University of Minnesota St. Anthony Falls Laboratory tested these samples for phosphorus and metals.

In July 2018 researchers collected three core samples from the ditch check sides and the filter to test for retained phosphorus and signs of diminished performance. 

What Did We Learn?

The iron-enhanced ditch check filter successfully removed phosphorus during the majority of the 40 rain events, reducing the phosphate mass loads between 22 percent and 54 percent. However, the cumulative phosphorus retention in the filter decreased from 42 percent in 2015 to 30 percent in 2016, 25 percent in 2017 and 23 percent in 2018. The core tests confirmed that the bottom 3.9 inches of the filter media filtered most of the inflow volumes of the runoff. This heavy runoff load reduced its sorption capacity over three years while the upper part of the filter was active only infrequently.  

“Enhancing ditch checks with iron filings will aid in the removal of phosphorus in stormwater. However, since the bottom of the filter receives the most flow, more frequent mixing of the iron filings is required than originally anticipated,” said Beth Neuendorf, water resources engineer, MnDOT Metro District.

The ditch check itself showed a somewhat lower phosphorus retention performance than the filter insert, though performance varied some years. Researchers considered that the soil and sod covering may have leached phosphates into the ditch check and filter insert, affecting its overall performance.

Neither the ditch check nor the filter insert were very effective in copper and zinc retention, although the metal concentrations in the inflow and treated runoff were generally lower than in typical highway runoff.

Regarding maintenance, researchers recommended the filter insert medium be mixed up every other year to redistribute the filter media at the bottom. They also recommended that the entire filter insert be replaced after six years.

What’s Next?

Researchers presented possible design changes that could improve performance, such as using peat instead of soil and sod to cover the ditch check. They also suggested installing ditch checks in series and re-engineering the filter to address the findings revealing the heavy runoff load taken by the filter’s bottom 3.9 inches. Reducing the depth of the filter berm could avoid the excessive inundation of the bottom media while the upper portion remains unused. Maintenance frequency could then be reduced.

This post pertains to Report 2019-27, “Iron-Enhanced Swale Ditch Checks for Phosphorus Retention,” published July 2019. For more information, visit the MnDOT project page.

New Project: Use of Innovative Technology to temporarily Deter Bat-Bridge Use Prior to and During Construction

MnDOT has funded a study to evaluate the use of non-lethal ultrasonic acoustic devices to temporarily deter bats from bridges before and during construction projects.

Background

Brown bat on bridge

When protected bats roost or form colonies on bridges, bridge repair and replacement projects have to follow regulatory requirements to minimize impacts on species protected by state and federally regulations – including the Endangered Species Act. These regulations protect bat populations that have already declined due to white-nose syndrome, which is estimated to have killed more the 5.7 million bats in eastern North America since 2006. The northern long-eared bat (Myotis septentrionalis) is listed as a threatened species as it is one of the species most impacted by white-nose syndrome. Other species are anticipated to be protected as the disease spreads.

To minimize disturbance to protected bats, which may use bridges both for day roosting habitat and sites for maternity colonies where bats give birth and raise their young, MnDOT is evaluating the feasibility and efficacy of ultrasonic acoustic devices to temporarily deter bats from work areas on bridges. These devices emit a sound, inaudible to humans, that disrupts the bat’s ability to echolocate and therefore discourages bats from approaching. This new technology has been utilized for wind turbines with positive results.

Ultrasonic device to deter bats

Temporarily deterring bats from a work site saves taxpayers money and increases bat safety. Regulations for protected species can limit activity that is potentially harmful, including bridge work during times when bats may use bridges for roosts or maternal colonies. Without the use of deterrents, work may be delayed until bats vacate the bridge, which may not occur until bats retreat to hibernacula (such as caves and mines) for the winter. Having control over when bats are present will provide more predictable timelines to projects and reduce engineering and administrative costs associated with delays and changes to work plans. Without a control measure, projects must adhere to timing restrictions that increase construction costs and may even reduce bridge life expectancy. And if bats are kept away from construction sites, they will not be directly harmed or disturbed by the activity.

Project Scope

This one-year study will investigate the efficiency and feasibility of ultrasonic bat deterrent technology for temporary exclusion of bat species on bridges by monitoring bat presence before the ultrasonic devices are installed, during a trial period, and after devices are removed. This technology will be tested on two bridges in Minnesota. Findings (expected in May 2020) will determine if ultrasonic bat deterrent technology can be utilized to exclude bats from construction and maintenance work zones, thereby reducing costs and ensuring the safety of protected species.

Watch for new developments on this project.  Other Minnesota research can be found at MnDOT.gov/research.

Roadside Turf That Tolerates Salt, Heat and Ice

A recently completed research study has identified turfgrass species and cultivars that perform best under the heat and salt on Minnesota roadsides.

Varieties from fifteen turfgrass species were tested in salt, heat and ice stress protocols. Analysis of color and cell membrane stability yielded recommendations for salt- and heat-resistant turfgrasses, but was inconclusive for ice-resistant cultivars. A mixture of cultivars was recommended for field study.

What Was the Need?

Minnesota’s roadside vegetation prevents erosion and keeps contaminants from reaching ground- and surface water. Turfgrass offers aesthetic value and unobstructed sightlines for drivers, but it must withstand harsh conditions.

Yellowing turfgrass in winter alongside Interstate 94.

In addition to year-round contaminants generated from highway traffic, Minnesota roadside grasses face snow, ice and salt from deicing operations in winter, and heat in summer that is even hotter alongside roadways and in urban environments.

Various turfgrass species may offer better resistance to specific stressors. Several current and recent MnDOT studies have evaluated salt tolerance and watering needs for select species of turfgrass. It was unclear, however, which species performed best under the multiple, combined stressors of Minnesota roadway environments, and would suit a mixture tailored to one of three Minnesota climate regions that could optimize turfgrass performance throughout the year.

What Was Our Goal?

This project sought to identify turfgrass species and cultivars that perform well under the range of stressors common to Minnesota roadsides. Successful cultivars may be candidates for turfgrass mixtures of multiple species that would optimize performance under all conditions in the field.

What Did We Do?

Researchers conducted a literature search to identify promising turfgrass species for harsh environments. Then they contacted seed companies for further recommendations before requesting seeds for multiple cultivars from 15 species. Next, researchers tested cultivars in salt, heat and ice stress protocols. Results from this testing are summarized below.

Salt Stress. The research team grew 38 individual cultivars hydroponically in 4-inch pots for 12 weeks. Then they suspended the pots in a salt solution for three weeks. Salt was added at the end of three weeks and again at three-week intervals at four salt concentration levels. Investigators compared digital images of green cover with in-pot color index meter results and tested cell membrane stability by measuring electrolyte leakage.

Heat Stress. Investigators grew eight samples each of 34 cultivars in 4-inch pots in a greenhouse for 12 weeks. Plants were trimmed manually to 2 inches. Half the plants were put through three heat stress cycles of 49 days of 95 degrees Fahrenheit and 70 percent humidity, followed by 28 days of normal conditions. Researchers then conducted digital imaging, in-pot color indexing and electrolyte leakage testing.

Ice Stress. After 10 weeks in a greenhouse, four samples each of 35 cultivars were placed in cold acclimation for 14 days at 35.6 degrees Fahrenheit. Investigators then moved pots to a chamber held at 28.4 degrees for 24 hours to freeze the soil, and then applied 2-inch layers of ice to each pot. A sample of each cultivar was removed at four, eight, 12 and 16 weeks, thawed for 48 hours in a 35.6 degree chamber and then moved to a greenhouse. Digital images were taken at 31 days in a greenhouse. A second batch was run as a control through the same trial up to the point of ice cover to identify if cold temperature was fatal to any samples.

A grid of 16 photographs shows green cover for four turfgrass cultivars: tall fescue, perennial ryegrass, Kentucky bluegrass and hard fescue. Increasing damage from salt exposure is shown for each cultivar after one, six, nine and 12 weeks.
A grid of 16 photographs shows green cover for four turfgrass cultivars: tall fescue, perennial ryegrass, Kentucky bluegrass and hard fescue. Increasing damage from salt exposure is shown for each cultivar after one, six, nine and 12 weeks.

What Did We Learn?

A mixture of turfgrass varieties and species will likely be the best solution for year-round use in Minnesota, as no one cultivar performed well in every trial.

Salt Stress. Tall fescue and perennial ryegrass sustained the highest percent green cover and lowest electrolyte leakage throughout the salt stress trials. Alkaligrass, considered salt tolerant, did not perform significantly better than other grasses. Only tall fescue emerged as a salt-resistant turfgrass option, though this cultivar is vulnerable to ice cover.

Heat Stress. Performance varied significantly within species, suggesting a potential for breeding improvements. Some species performed poorly under heat but recovered well when returned to normal conditions. Researchers recommended Canada and Kentucky bluegrasses, tall fescue, strong creeping red fescue and slender creeping red fescue as heat-resistant turfgrass cultivars.

Ice Stress. Tall fescue performed best in image and color analysis. Field observations and previous study, however, suggest that tall fescue performs poorly under ice cover. Warm season grasses died during the control cold storage. Researchers concluded that the ice trial did not properly simulate field ice cover conditions.

What’s Next?

The second phase of this study began in 2018 and employs a mixture of six species selected from this study: Kentucky bluegrass, slender creeping red fescue, hard fescue, buffalograss, alkaligrass and tall fescue. Mixtures will be planted in different combinations on roadsides for evaluation. MnDOT will also adjust its seed mixture recommendations for use in the meantime based on the results of this and other studies. Ultimately, MnDOT intends to develop recommendations tailored to three climate regions in Minnesota.

This post pertains to the LRRB-produced Report 2019-01, “Regional Optimization of Roadside Turfgrass Seed Mixtures,” published December 2018. For more information, visit MnDOT’s Office of Research & Innovation project page.

Study Underway to Harness Renewable Energy from Minnesota’s Highways

Sound barriers and snow fences along highways have the potential to provide clean energy in Minnesota.

A newly funded MnDOT study, Harnessing Solar Energy through Noise Barriers and Structural Snow Fencing, is investigating how to utilize existing noise barriers and snow fences on Minnesota highways to harvest clean, cost-effective energy.

“Snow fences and noise walls are structural barriers with a singular purpose. Snow fences are intended to limit snow from drifting onto our highways and noise walls are intended to reduce noise to a comfortable level for communities living near our highways. Finding a way to integrate solar that maintains their structural integrity could transform the use of these barriers from single purpose to multi-purpose,” says Dan Gullickson, MnDOT’s Blowing Snow Control Shared Services Program Supervisor, who is overseeing the research project.

Solar energy is energy captured from the sun and converted into thermal or electrical energy. It is a clean and abundant renewable energy source and generally requires very little maintenance after installation. Solar energy has a variety of uses, including providing electricity to power street lamps and homes, heating and cooling spaces, and heating water.

“We’ve seen some applications of solar panels on noise walls—primarily in European countries—but the addition of solar panels to snow fences is an entirely new concept,” says Gullickson.

The innovative nature of this project brings many unknowns that MnDOT hopes to answer, such as: Is it possible to engineer these structures without disrupting their functionality? What safety measures need to be taken to ensure the public and MnDOT workers stay safe if they come into contact with the panels? What are the lifecycle costs of installing and maintaining solar? How much energy could they generate and how does that connect with existing power grids?

One estimate shows that a thousand miles of solar panels could power all the street lights along Minnesota highways or 43,333 residential homes. (Assuming each solar panel is 330W and 1,000 panels could generate up to 330kW per mile.)

Harnessing solar energy on Minnesota highways: Solar energy can be used for heating, cooling, lighting, and warming water. 1,000 miles of solar panels on Minnesota highways could power: All of minnesota highway lights o 43,333 residential homes.

“We know Minnesota and North Dakota winters bring a lot of snow—which is disruptive to our travelers and farmers. We hope to create a sustainable solution that aids drivers and farmers, but also harnessing energy which would be able to offset the cost of construction and installation,” says Mijia Yang from North Dakota State University, the lead researcher.

Gullickson and a diverse team of MnDOT experts – from the field of environmental stewardship to traffic engineering – will guide the research and review findings.

The study will include surveys, lab testing or modeling of possible design options and a cost-benefit analysis—planned to be completed by of June 2021.

Currently, the research team is developing surveys to better understand public opinion on solar energy (including energy prices and solar panel infrastructure), power companies’ interest in purchasing solar energy generated through the right-of-way and legal considerations for harvesting solar energy through the rights-of-way.

 “Surveying the public and utility providers may uncover questions that we hadn’t previously anticipated. We hope to address those hurdles throughout the study,” says Gullickson. Follow along for project updates on MnDOT’s Office of Research & Innovation website.

Culvert Design Manual Provides Guidance for Accommodating Fish Passage

Several years of research have culminated in the publication of a culvert design manual that promotes the safe passage of fish and other aquatic organisms, as well as stream connectivity, throughout the state.

“Engineers designing culverts for Minnesota’s diverse ecological regions will benefit from this document, which offers sound guidance from many practicing experts about how to design culverts that allow aquatic organism passage and preserve stream integrity,” said Petra DeWall, former Bridge Waterway Engineer, Minnesota Department of Transportation (MnDOT).

What Was the Need?

Minnesota’s 140,000 miles of roads and approximately 92,000 miles of streams and rivers meet at tens of thousands of places. Culverts are a cost-effective solution to allow traffic to cross over smaller waterways. Historically, culverts have been designed with the safe passage of vehicles in mind. Recently, a state and national appeal for the safe passage of fish and other aquatic organisms, as well as for waterway integrity and connectivity, has influenced culvert design.

A pair of Topeka shiner fish
The Topeka shiner, once found throughout the state, is one species of federally endangered fish in Minnesota that must traverse culverts to survive.

MnDOT has supported many research projects examining fish and aquatic organism passage (AOP) through culverts, and nationally, a number of published resources exist on appropriate design. Because of the variety of ecological regions in the state, the range of culvert geometries and many other factors, no single solution can accommodate AOP through culverts statewide. A comprehensive culvert design guide was needed to inform designers about solutions that can effectively facilitate the movement of fish and other aquatic organisms in Minnesota while maintaining healthy streams.

What Was Our Goal?

The objective of this project was to produce a comprehensive and accessible culvert design guide that could be used by Minnesota practitioners to design culverts for AOP and stream connectivity. The guide would provide the following benefits:

• More efficient culvert design and permitting process for AOP.
• A central definition of typical designs, which would improve contractors’ familiarity with designs and lower construction costs.
• Avoidance of designs that could be detrimental to the natural environment.
• Avoidance of designs likely to lead to roadway damage and need for repairs.
• Fishery improvement through increased stream connectivity.

What Did We Do?

To determine the scope of the guide, researchers worked with experts from the Minnesota Department of Natural Resources (DNR), the U.S. Forest Service and others with knowledge of civil engineering, AOP and stream geomorphology.

They then sought information for the guide from a wide range of authoritative resources. A literature search examined current and past research by the research team and others; guidance documents from federal agencies; guidance from other states; permit requirements from the DNR and other agencies; and databases of fish populations, stream attributes and culvert data. The literature search also sought to reveal gaps in knowledge where further research specific to Minnesota was needed.

Additionally, researchers surveyed a cross section of highway design engineers and managers from MnDOT, county and city agencies, resource agencies and engineering consultants to identify current design practices for AOP and stream connectivity, and the degree of their effectiveness.

What Did We Learn?

The project resulted in the Minnesota Guide for Stream Connectivity and Aquatic Organism Passage Through Culverts, a thorough guide for culvert designers, hydraulic engineers and others involved in culvert design and construction in Minnesota. Topics addressed in the guide include:

• The need for culvert designs that include AOP and stream connectivity, as well as the current regulatory context.
• An overview of culvert design, categories of design methods that incorporate AOP and waterway connectivity, and a list of best practices.
• Site characteristics, analysis and tools related to energy dissipation, hydraulic analysis for AOP and sediment transport.
• A design method selection chart, information on certain designs and references for further information.
• Further guidance about design issues such as multiple barrel and floodplain culverts, grade control, retrofits and other cost considerations.

What’s Next?

The culvert design guide will be made available to users online. Future considerations for this project include an associated webinar and efforts to coordinate information presented in the guide with expectations and permitting requirements of MnDOT departments charged with culvert creation and implementation. Additional research is underway to assess culverts and fish passage with respect to storm vulnerability and future hydrologic scenarios.

This post pertains to the MnDOT and LRRB-produced Report 2019-02, “Minnesota Guide for Stream Connectivity and Aquatic Organism Passage Through Culverts,” published January 2019.

Pilot Program Promotes Benefits of Snow Fences

A new program piloted in western Minnesota to increase snow fence use among private landowners has been so successful that MnDOT is looking at rolling it out statewide.

The University of Minnesota’s Center for Integrated Natural Resource and Agricultural Management worked with MnDOT District 8 staff for more than a year to develop and test a snow fence outreach program that could be used by MnDOT district offices.

“After our training, we saw a 300 percent increase in the number of standing corn rows, and that was on the initiative of a few people in the maintenance group. We’d like to spread the training to other districts,” said Dean Current, Director, University of Minnesota Center for Integrated Natural Resource and Agricultural Management.

Background

Living snow fences are natural vegetative barriers that trap blowing snow, piling it up before it reaches a road, waterway, farmstead or community. It could include leaving a few rows of corn or hay bales along the road side, or even temporary fencing.

MnDOT has about 3,700 sites that are suitable for snow fences. It estimates that if 40 percent of problematic sites had snow fences, the state could save $1.3 million per year in snow management costs. Despite the cost, safety and environmental benefits, private landowners have shown limited interest in the program. An effective outreach program was needed along with strategies for identifying MnDOT personnel who could promote the practice and recruit landowners to the program.

“If we can implement our blowing snow control program more consistently, we can help reduce crash severities, improve operational efficiencies due to snow and ice control measures, and improve the mobility of the public,” said Dan Gullickson, Snow Control Program Administrative Coordinator, MnDOT Office of Environmental Stewardship.

How Did We Do It?

In January 2016, investigators surveyed MnDOT District 8 employees to gauge their understanding of snow fences as well as their approach to working with landowners to implement blowing snow control measures. The investigators studied survey responses to assess awareness of and interest in promoting the use of snow fences and grading to reshape road environments for snow and erosion control. They also examined snow fence programs from around the country, identifying types of snow fences used and characteristics of programs that successfully recruit landowner participation.

A permanent snow fence along a rural highway.
A permanent snow fence along a rural highway.

Results from these efforts were used to design an outreach program that was presented to District 8 staff. In January 2017, investigators surveyed the staff to evaluate the training and redesign the program accordingly. Finally, investigators evaluated market values of various snow fence designs.

What Was the Impact?

Initial survey results identified two relevant types of district personnel: maintenance and program delivery staff. Maintenance staff involved in plowing and road care interact more with landowners than do program delivery staff, who design or redesign roadways and may be involved in acquiring land for snow fences. Though tailored for each group, all training described the MnDOT blowing snow control program and its implementation, the role of snow fence coordinators, operational benefits and awareness of how promotion of the program fits within the scope of an employee’s duties.

Keys to the success of snow fence programs around the country include strong relationships and direct communication with local landowners, funding, landowner interest in conservation and public safety, and observable benefits.

A follow-up survey showed marked improvement in staff knowledge of the program and willingness to promote it. Landowner participation grew from four sites to 15 in the year after training, due mostly to maintenance staff participation. Survey respondents suggested potential program improvements such as more program champions; outreach in spring and summer at community and farmer gatherings as well as at local and state fairs; and a clearer understanding of how program promotion fits within job responsibilities.

The market study demonstrated that nonliving snow fences, though the most expensive option for MnDOT, offer the largest benefit per acre. Landowners seem to prefer living snow fences and standing corn rows. MnDOT may wish to raise the annual payment for all living snow fences.

What’s Next?

Considerations for MnDOT include implementing the training program in other districts, further defining central and district staff roles in snow fence promotion and implementation, incentivizing snow fence champions, developing more outreach material and maintaining relationships with landowners.

A new project currently under way aims to further expand these efforts.

This post pertains to Report 2017-42, “Expanding the Adoption on Private Lands: Blowing-and-Drifting Snow Control Treatments and the Cost Effectiveness of Permanent versus Non-Permanent Treatment Options.” Related research can be found by searching “snow fences” under “Projects” at MnDOT.gov/research.

 

New Project: Re-Using Water at Safety Rest Areas and Truck Stations

Water is being drawn out of the state’s aquifers faster than it is being replenished, so public agencies like MnDOT are increasingly interested in figuring out how to reduce water usage.

A two-year research project underway at MnDOT is investigating how the agency can re-use wastewater at its safety rest areas and truck-washing stations. In addition to preserving groundwater, MnDOT hopes to reduce utility and septic system costs.

MnDOT owns and operates over 1,000 buildings, including 68 safety rest areas, 137 truck stations, 18 regional/headquarters maintenance sites and 15 weigh stations and truck scales.

These facilities either discharge their wastewater to a subsurface sewage treatment system or a wastewater treatment plant.

Truck station with vehicles in parking lot
Maplewood Bridge Truck Station

Researchers from the University Of Minnesota’s Onsite Sewage Treatment Program have been hired to investigate the potential avenues for wastewater re-use at MnDOT. They will consider when re-use makes sense from a regulatory, environmental, economic and management perspective; recommend the most appropriate applications for reuse and identify any challenges with implementation.

Potential benefits include:

  • Preserve ground and drinking water for potable drinking.
  • Reduced life-cycle costs in areas where low-producing wells could meet drinking water needs while reused wastewater could be used for toilet flushing and equipment wash-down.
  • In areas with municipal water, lower water utility costs.
  • Increased longevity of septic systems due to decreased loads.

As the state, counties, or cities construct new facilities or upgrade existing ones, this research will provide insight into what options are readily available to reduce water consumption and improve water efficiency. If these types of reuse systems are demonstrated by MnDOT, then they could lead to usage by other properties across Minnesota.

Watch for new developments on this project.  Other Minnesota research can be found at MnDOT.gov/research.