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Culvert Design Transportation & the Environment Conference December 3, 2014 Chris Freiburger – Fisheries Division - DNR Perched Piping

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Culvert Design Transportation & the Environment Conference December 3, 2014 Chris Freiburger – Fisheries Division - DNR Perched Piping Culvert Design Transportation & the Environment Conference December 3, 2014 Chris Freiburger – Fisheries Division - DNR Perched Piping Blockage Sediment What are we after? •Natural and dynamic stream channel •Passage of all aquatic organisms •Low maintenance, flood-resilient road Sizing & Placement of Stream Culverts The Stream Will Tell You! •Match Culvert Width to Bankfull Stream Width •Extend Culvert Length through side slope toe •Set Culvert Slope same as Stream Slope •Bury Culvert 1/6th Bankfull Stream Width •Offset Multiple Culverts (floodplain ~ splits lower buried one) (higher one ~ 1 ft. higher) •Align Culvert with Stream (or dig with stream sinuosity) •Consider Headcuts and Cut-Offs Dr. Sandy Verry Chief Research Hydrologist Forest Service Mesboac Culvert Design – 0’ • Match 3’ Bankfull width 6’ • Extend Culvert to side slope toe • Set on Channel Slope Set Slope Failure to set culverts on the same slope th as the stream (and bury them 1/6 widthBKF) is the single reason that many culverts do not allow for fish passage! Slope can be measured as: Slope along the bank (wider variation, than thalweg) Slope of the water surface (big errors at low flow or in flooded channels, good at moderate to bankfull flows) Slope of the thalweg (this, by far, is the best one) Measure a longitudinal profile to allow the precise placement of culverts. Precision Setting is the key to a fully functional riffle culvert installation At each point riffle 1. Bankfull riffle 2. Water surface Setting the elevation 3. Thalweg of the culvert invert True North Backsight upstream & riffle Benchmark downstream assures success! riffle riffle Measure Bankfull elevation, water surface elevation, and major thalweg topographic breaks (riffle top, riffle bottom, pool bottom), at each station, on the longitudinal profile 1997 LITTLE POKEGAMA CREEK PLOT 7 LONGITUDINAL 1003 1002 1001 1000 FT - 999 998 Bankfull elevation 997 ELEVATION 996 Slope = 0.0191 Water Surface elevation 995 Thalweg elevation 994 993 0 50 100 150 200 250 300 350 400 THALWEG DISTANCE-FT 1. A line connecting the thalweg riffle points from above and below the crossing site is the most accurate estimate of stream bottom 1997 LITTLE POKEGAMA CREEK PLOT 7 LONGITUDINAL 1003 2. Subtract burying depth from 1002 these elevations to find the 1001 elevation of the inverts 1000 FT - 999 998 Bankfull elevation 997 ELEVATION 996 Slope = 0.0191 Water Surface elevation 995 Thalweg elevation 994 993 0 50 100 150 200 250 300 350 400 THALWEG DISTANCE-FT 1. A line connecting the thalweg riffle points from above and below the crossing site is the most accurate estimate of stream bottom Measuring points needed to define the longitudinal profile for a (A) pool-riffle channel (B) step-pool channel (C) and cascade channel Mesboac Culvert Design – 0’ 1’ 2’ 3’ • Consider headcut Qualitatively evaluate bank stability by observing: • Bank materials and their layering • Rooting depth, density and root sizes • Large, stable woody structure on banks • Live trees and shrubs that may overhang banks • Evidence of active bank erosion No culvert Improperly set culvert Aggradation Scour pool Culvert replaced properly Note gradient increase Stream Thalweg Stream Slope Culvert If you don’t address grade! Deciding how to handle any expected headcutting requires answers to questions such as the following: • How much headcutting is likely if no controls are implemented? How far upstream might it go? • What effects will the expected headcut have on streambed and banks? How long will they last? • Should headcutting be prevented? • Should headcutting be allowed to occur at an uncontrolled rate? • Should the rate of headcutting be slowed by temporary grade controls? Stream: Location: Station: Observers: Date: Stream Type: Valley Type: BEHI Score Study Bank Height / Bankfull Height ( C ) (Fig. 5-19) Study Bankfull Bank Height ( A ) / ( B ) = Height (ft) = (A) (ft) = (B) (C) Root Depth / Study Bank Height ( E ) Root Study Depth Bank ( D ) / ( A ) = (ft) = (D) Height (ft) = (A) (E) Weighted Root Density ( G ) Root Density ( F ) x ( E ) = as % = (F) (G) Bank Angle ( H ) Bank Angle as Degrees = (H) Surface Protection ( I ) Surface Protection as % = ( I ) Bank Material Adjustment: Bedrock (Overall Very Low BEHI) Bank Material Boulders (Overall Low BEHI) Adjustment Cobble (Subtract 10 points if uniform medium to large cobble) Gravel or Composite Matrix (Add 5–10 points depending on Stratification Adjustment percentage of bank material that is composed of sand) Add 5–10 points, depending on position of unstable layers in (Add 10 points) Sand relation to bankfull stage Silt/Clay (no adjustment) Very Low Low Moderate High Very High Extreme Adjective Rating and 5 – 9.5 10 – 19.5 20 – 29.5 30 – 39.5 40 – 45 46 – 50 Total Score Bank Sketch 1 Root Depth (D) Bank (A) Angle (H) Bankfull Height BANK STUDY Surface Height (B) Height Protection (I) BANKFULL Vertical distance (ft) Start of 0 Bank 0 1 Horizontal distance (ft) Use cross vanes as grade control to permanently set a channel invert Range of Crossing Ecological Objectives With fish passage as the overall goal, economics, site logistics, regulatory requirements and roadway characteristics may dictate a particular design procedure. • Geomorphic Simulation recreate or maintain natural stream reach geomorphic elements including slope, channel-bed width, bed materials and bedform by using the reference reach. • Hydraulic Simulation techniques utilize embedded culverts, natural or synthetic bed mixes and natural roughness elements such as oversized rock to provide hydraulic conditions conducive to fish passage. • Hydraulic Design techniques create water depths and velocities that meet the swimming abilities of target fish populations and life stages during specific periods of fish movement. Infrastructure Safety and Service Life Culverts “must” be built with consideration of safety and service life. Larger span culverts will have a greater cross-sectional area for passing flood events. Smaller culverts will have a smaller initial cost, but require additional maintenance and monitoring to avoid debris accumulation (Bates et al. 2003). Total roadway-stream crossing cost includes several other capital and recurring items such as installation and long-term maintenance. Perched Culvert Longitudinal Profile Culvert Outlet THE BAD…… Drop Structure Downstream Upstream THE BEST ….. Bridge Tributary to Kraft Creek Step Pool 8.5% slope Functioning culvert means transporting not only water but……..SEDIMENT! It may also be necessary to raise the tailwater elevation in order to backwater the culvert and provide minimum flow depths. Sometimes this is all that's required to retrofit. Many methods are available including: • Weirs • Baffles • Constructed tailwater pools • Full or partial channel restoration • Riffle grade control structure/Roughened Channel Flow over weirs can create velocity and depth barriers, and it may be necessary to design a series of weirs to provide fish passage and backwatering the culvert. Ole’ Bitty Creek, Berrien County Garfield Lake Drain Culvert Outlet boulder weirs Looking Downstream Looking Upstream Navarro River, California Concrete Weirs 2.4% slope Peacock Creek, California In Culvert and Downstream Grade Control 6.5% slope John Hatt Creek Photo Courtesy of Washington Dept of Fish and Wildlife Smith River, California In Culvert and Downstream Grade Control 4.3% slope Upper Pack River, Northern Idaho Stream Simulation Step-Pool System 3.5% slope Mynot Creek, California Stream Simulation 1% slope UnNamed Tributary to the Pacific Ocean In Culvert Grade Control Roughened Channel with Banks 1.2% slope Roughened Channel Roughened Channel Two possible project profiles www.mcgi.state.mi.us/miculverts/ Future Steps • Data Collection – Coarse Level – Road Soft – Tablet – Access • Sorting and Prioritizing • Modeling • Project Implementation Patrick Ertel Michigan Department of Natural Resources Fisheries Division – Habitat Management Unit 989.732.3541 x5047 [email protected].
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