Non-modeling Worksheets: Bridge Replacement in Kind

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1 Non-modeling Worksheets: Bridge Replacement in Kind April 12, 2016 Darrin Miller PE Hydraulic Engineer Section Manager (North)

2 Overview Intent - When to use the Worksheet Theory behind the Worksheet Bridges and Culverts Examples

3 Non-Modeling Worksheet When to Use the Worksheet Bridge to Bridge replacement Culvert to Bridge replacement Culvert to Culvert replacement If the length of the culvert is essentially the same And if the proposed culvert is of essentially the same material (roughness coefficient) RAS_4.0_Reference_Manual.pdf (page 6-24) Concrete is typically smoother than corrugated metal, smaller n, less loss, lower surcharge Note: If multiple designs, the applicant should only submit the one with the smallest waterway opening for use in the worksheets April 12, 2016

4 Non-Modeling Worksheet When to Not Use the Worksheet The waterway opening decreases The existing structure remains in place Bridge to Culvert replacement If the New bridge is more than 500 ft from the existing bridge

5 Non-Modeling Worksheet How to Use the Worksheet The worksheet was intended to streamline the majority of replacement in kind projects BUT, it does not capture every possibility Single page Excel with if then statements

6 Non-Modeling Worksheet How to Use the Worksheet The worksheet was intended to streamline the majority of replacement in kind projects BUT, it does not capture every possibility 1) It works for my bridge: submit worksheet 2) It does not work for my bridge: modeling 3) It does not work for my bridge, BUT it should include documentation for DNR review to fill in the missing info not captured by the Excel worksheet

7 Two Part Application Non-Modeling Worksheet Directions for use Minimum Requirements Check Sheets Plan Details Companion Worksheet B Excel Spreadsheet with embedded logic to evaluate entries Yes/No questions with dropdown choices Tables for recording relevant data

8 Minimum Requirements Plan view of construction components Aerial of disturbed area Delineated Floodway through the project Plan views with calculations of waterway opening, top of road profile, and low structure Cross section location map Project location map Site photos

9 Companion Worksheet B Questions are asked in an order so that the applicant will move through the worksheet as quickly as possible while providing as little information as is needed to determine the ability to issue a permit for the project Logic is coded into the spreadsheet so the applicant is only asked for applicable data

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12 Culverts & Bridges Why is it important to consider if it s a bridge or culvert? When modeling in HEC-RAS, bridges and culverts are modeled differently which can give drastically different results Bridges are modeled using the methods selected in the bridge modeling approach editor (Energy, Momentum, Pressure and/or Weir, )

13 Culverts & Bridges Why is it important to consider if it s a bridge or culvert? Culverts also come in many different shapes (box, arch, circular, ellipse, ) Culverts can be made of different materials which have different roughness coefficient Culverts are modeled using inlet or outlet control culvert equations and when applicable weir equations

14 Culverts & Bridges When is it a bridge and not a culvert? Consider bridge methods when the structure has a very large opening relative to the deck thickness Consider culvert methods when the structure has a very deep deck and small relative opening FHWA defines a culvert as a structure with a total span of 20 ft or less (measured along centerline of roadway)

15 Culverts & Bridges FHWA defines a culvert as a structure with a span of 20 ft or less (measured along centerline)

16 Non-Modeling Worksheet So when can I use the worksheet? Theory behind logic is to approve in-kind Would the same equations be used to model both structures?

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21 Companion Worksheet B Regulatory Flood Elevation (RFE) is needed to evaluate the area available below the RFE At toe of road fill Acceptable sources: a published Flood Study a Letter of Map Revision (LOMR) an approved model(s) from a DNR permit a DNR Floodplain Analysis and Regulatory Assessment (FARA) a new model submitted with the permit application for DNR review

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23 Supporting Documents Minimum submittal requirements listed on the evaluation worksheet Submit all that is needed to support the calculations and values in the RIK assessment worksheet. If your project is unique, submit the nonmodeling assessment with the supporting documentation and DNR can review.

24 Examples Bridge deck improvements result in thicker deck. The low chord of the proposed bridge (red line) has a lower elevation than existing. Does it qualify? Existing Proposed 1% BFE

25 Examples Yes. The area of the waterway opening beneath the structure is decreasing. But since the BFE is known, it can be shown that the area below the BFE is NOT changed. Existing Proposed 1% BFE

26 Examples The proposed road profile is raised and minimum top of road remains unchanged. Does it qualify? Proposed road profile 1% BFE Minimum top of road

27 Examples No, the worksheet captures the high structure elevation, and the minimum top of road. But additional road fill may block road overflow. Proposed road profile 1% BFE Minimum top of road

28 Examples The proposed road profile will be raised above the existing minimum top of road. Does it qualify? Proposed road profile 1% BFE Minimum top of road

29 Examples Yes, the worksheet captures the high structure elevation, and the minimum top of road. Both are above the BFE. Proposed road profile 1% BFE Minimum top of road