Browsing by Subject "Aquatic life"

Now showing 1 - 3 of 3
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    Minnesota Guide for Stream Connectivity and Aquatic Organism Passage through Culverts
    (Minnesota Department of Transportation, 2019-01) Hernick, Matthew; Lenhart, Christian; Kozarek, Jessica; Nieber, John
    This guide assists Minnesota culvert designers in identifying, selecting, and implementing appropriate designs for maintaining aquatic organism passage (AOP) and stream connectivity at road-stream intersections. It was synthesized from existing literature and culvert design documents, a survey of Minnesota practitioners, research, and input from local, regional, and national experts. Culvert designs that create excessive velocity, physical barriers, or shallow depth can disrupt AOP and may be detrimental to the continuity of water flow, sediment, and debris transport vital to stream health. Conversely, the recommended culvert designs in this guide account for stream parameters such as slope and substrate that vary across Minnesota landscapes. A set of best practices captures critical design elements based on stream characteristics, which can be summarized as follows: 1.) Design the culvert to be similar to the stream channel (reference reach) by matching its slope, alignment, bankfull width, and flow depth to maximize AOP; 2.) Provide a continuous sediment bed with roughness similar to the channel, while maintaining continuity of sediment transport and debris passage, and; 3.) Design for public safety, longevity, and resilience. Culvert design that improves AOP and accounts for sediment transport is expected to reduce long-term maintenance costs and increase culvert life span.
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    Sediment Transport through Recessed Culverts: Laboratory Experiments
    (Minnesota Department of Transportation, 2015-03) Kozarek, Jessica; Mielke, Sara
    Recessed culverts are often installed in Minnesota to facilitate aquatic organism passage (AOP) by providing a natural streambed through the culvert. The least expensive option when installing a recessed culvert is to allow the culvert to fill in with sediment naturally over time; however, previous field studies suggest that in many cases, sediment fails to deposit within the culvert. The objective of this research was to understand the function of a culvert set below the streambed elevation under various sediment transport conditions. Laboratory experiments were designed to assess the performance of recessed culverts across a range of geomorphic characteristics representative of Minnesota streams. These experiments explored the functionality of a culvert that is prefilled with sediment representative of the stream as a part of the installation process against one that is empty after installation and assessed the potential for headcutting and downstream degradation. The experiments evaluated the need for artificial roughness installations within recessed culverts in high gradient streams. Three sets of experiments were conducted examining: 1) the effect of sediment grain size, slope, and flow hydrograph on sediment transport through a single recessed box culvert, 2) the effect of bed roughness structures on sediment stability in a single recessed box culvert in high-gradient streams, and 3) the effect of culvert offset and skew on sedimentation in multi-barrel culverts.
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    Validation of Wetland Mitigation in Abandoned Borrow Areas – Phase II
    (Minnesota Department of Transportation, 2016-03) Johnson, Kurt W.
    Road construction in northeast Minnesota often causes wetland impacts that require compensatory mitigation. Borrow areas excavated for road construction material can be developed into wetland mitigation sites if hydric vegetation, hydric soils and adequate hydrology are provided. Fourteen wetland mitigation sites were constructed north of Virginia, Minnesota along the U.S. Trunk Highway 53 reconstruction project corridor. The sites were established with the goal of mitigating for project impacts to seasonally flooded basin, fresh meadow, shallow marsh, shrub swamp, wooded swamp, and bog wetlands. Monitoring results indicate that the 14 mitigation sites range in their potential to receive wetland mitigation credit. All but one of the sites consistently meet wetland hydrology criteria. The sites contain a variety of plant communities dominated by wet meadow, sedge meadow, and shallow marsh. Floristic Quality Assessment (FQA) condition categories for the sites range from "Poor" to "Exceptional." Invasive plant species, particularly reed canary grass and narrow leaf cattail, are present on a number of sites and should be controlled. Tamarack and black spruce plantings have been successful on some of the drier areas and should be expanded to increase the quality and potential mitigation credit for other sites. These sites have shown the potential for creating mitigation wetlands in abandoned borrow pits in conjunction with highway construction. Adaptive management, particularly water level regulation, early invasive species control, tree planting, and continued long-term annual monitoring can make mitigation sites like these successful options for wetland mitigation credit. Continued site monitoring to determine potential for mitigation credit is recommended.