MI_NP_PIRO_11(2)_HYD_Memo.pdf

FHWA:W. Hiciano:6218:SE: M:\PROJECTS\piro\11(2)\Techserv\Hydra\Reports.docx CC: Hydraulics, Geotech, Env, HD Engineer, TS Engineer, Bridge

Form FHWA-201 U.S. DEPARTMENT OF TRANSPORTATION (Rev. 11-87) FEDERAL HIGHWAY ADMINISTRATION

MINUTE - MEMO

Use this form in lieu of transmittal slips within Dept. of Trans. when message comment is to be retained as file material. Do not prepare carbons. Not to be used in lieu of Form FHWA-121 for informal correspondence.

SUBJECT: MI NP PIRO 11(2) Hydraulic Analysis Memo

TO MESSAGE/COMMENT FROM/DATE

Jatinder Bains Project Manager

Shoukat Nawaz Highway Design Manager

We have completed the hydrologic and hydraulic analysis for the Miners River Bridge located at Pictured Rocks National Lakeshore in Alger County, Michigan. The purpose of this project is to provide recommendations for the Water Surface Elevations (WSEL) at the structure. This project consists of repairs or replacement to the existing steel bridge and the integrated Lamprey barrier.

Miners River Bridge is a single span structure, with a steel beam and concrete deck superstructure. The substructure consists of concrete footings, abutments and wingwalls, in addition there is a Lamprey structure upstream of the bridge opening, that is part of the substructure of the bridge.

Hydrology and Hydraulic Analysis A USGS stream gage is on site. The USGS stream gage: Miners River NR Munising, MI with the station number 04044755.

The design peak flows were obtained from the USGS stream gage station.

For the design peak flows for various return events refer to Table 1. The site has a contributing drainage area of 26.10 square.

Table 1: Flow Rates

Structure No. ID

5 yr (cfs)

10 yr (cfs)

25 yr (cfs)

50 yr (cfs)

100 yr (cfs)

04044755 408 487 586 654 725

The Federal Highway Administration software: Sedimentation and River Hydraulics – Two-Dimensional (SRH-2D) version 13.1.22 was used to simulate the existing hydraulic conditions for the structure, water surface elevations, and average velocities. The hydraulic model was developed using survey mapping, and FEMA floodplain delineations.

Summary of Findings and Recommendations

We performed multiple stream simulations with different stream flows, with the intent to determine the stream behavior at different flow stages. For this project, we are providing the water surface elevations for the following flood events; 5- year, 10-year, 25-year, 50-year and the 100-year storm event to determine the water surface elevations at the structure for repairs/design purposes.

Wendy Hiciano Hydraulics Engineer

Abhishek Kapoor Hydraulics Team Leader

7/27/2022 file://fhfl15fileserve.flhd.fhwa.dot.gov/data/PROJECTS/piro/11(2)/Techserv/Hydra/Reports/MI%20NP%20PIRO%2011(2)_Preliminary%20Hydraulic%20Memo.docx

Please refer to Table 2 for the water depth at the structure for the different storm event.

Table 2: Water Surface Elevations Flood Event (yr) Water Surface Elevations (ft)

5 619.05 10 619.47 25 619.97 50 620.29 100 620.64

Please contact us if you should have any questions or concerns.

file://fhfl15fileserve.flhd.fhwa.dot.gov/data/PROJECTS/piro/11(2)/Techserv/Hydra/Reports/MI%20NP%20PIRO%2011(2)_Preliminary%20Hydraulic%20Memo.docx

Attachments

1. NSS Report

2. Water Surface Elevations Profiles

3. Water Surface Elevations Cross Sections at the Bridge

4. Water Surface Elevations Upstream Cross Sections

5. Water Surface Elevations Downstream Cross Sections file://fhfl15fileserve.flhd.fhwa.dot.gov/data/PROJECTS/piro/11(2)/Techserv/Hydra/Reports/MI%20NP%20PIRO%2011(2)_Preliminary%20Hydraulic%20Memo.docx

NSS Report May 17, 2022 07:29AM

Michigan

Peak-Flow Statistics

Region_1

Region_1 Region Contributing Drainage Area = 26.1022 (mi ) Stream Slope 10 and 85 Method = 0.256 (ft/mi) Percent Length of Main Channel Swamps = 0.173 (%) Slenderness Ratio = 0.149 (dim) 24 Hour 100 Year Precipitation = 4.56 (in) Percent Outwash = 0.157 (%) Percent Peat and Muck = 0.17 (%) End Moraines of Fine Textured Till = 0.131 (%) Percent Medium Till = 0.124 (%) Percent Lacustrine Clay and Silt = 0.118 (%) Percent Thin Till over Bedrock = 0.074 (%) Percent Coarse Till = 0.054 (%)

[SEe, Standard Error of Estimate; SEp, Standard Error of Prediction; SE, Standard Error (other -- see report)]

Region_1 Region Value

Description (ft /s)

Maximum instantaneous flow that occurs with a 20% annual exceedance probability

(PK20AEP)

Maximum instantaneous flow that occurs with a 10% annual exceedance probability

(PK10AEP)

Study Area:

Statistic Group(s):

Regression Region(s):

Peak-Flow Statistics

Region_1 Region Value

Description (ft /s)

Maximum instantaneous flow that occurs with a 4% annual exceedance probability

(PK4AEP)

Maximum instantaneous flow that occurs with a 2% annual exceedance probability

(PK2AEP)

Maximum instantaneous flow that occurs with a 1% annual exceedance probability

(PK1AEP)

Holtschlag, D.J. and Croskey, H.M., 1984, Statistical Methods for Estimating Flow Characteristics of Michigan Streams: U.S. Geological Survey Water-Resources Investigations Report 84-4207, 80 p.

Region_1

PK20AEP =

PK10AEP =

PK4AEP =

PK2AEP =

PK1AEP =

Name Abbrev Description

Contributing Drainage Area

CONTDA

Area that contributes flow to a point on a stream

Stream Slope 10 and 85 Method

CSL10_85

Change in elevation divided by length between points 10 and 85 percent of distance along main channel to basin divide - main channel method not known

Percent Length of Main Channel Swamps

PLCHSWAMP

Percentage of the main channel length that flows through swamps

Citations

Appendix Equations

4.809 ⋅ ⋅ ⋅ ⋅(CONTDA)0.8931 (CSL10 _ 85)0.2164 (PLCHSWAMP + 1)−0.1741 (SLENR

4.59 ⋅ ⋅ ⋅ ⋅(CONTDA)0.8902 (CSL10 _ 85)0.2256 (PLCHSWAMP + 1)−0.1749 (SLENRA

3.987 ⋅ ⋅ ⋅ ⋅(CONTDA)0.8878 (CSL10 _ 85)0.2372 (PLCHSWAMP + 1)−0.1744 (SLENR

3.519 ⋅ ⋅ ⋅ ⋅(CONTDA)0.886 (CSL10 _ 85)0.2464 (PLCHSWAMP + 1)−0.1738 (SLENRA

3.035 ⋅ ⋅ ⋅ ⋅(CONTDA)0.8853 (CSL10 _ 85)0.2558 (PLCHSWAMP + 1)−0.1727 (SLENR

Explanatory Variable Definitions https://pubs.er.usgs.gov/publication/wri844207

Name Abbrev Description

Slenderness Ratio

SLENRAT

Main channel length - squared - divided by the contributing drainage area

24 Hour 100 Year Precipitation

I24H100Y

Maximum 24-hour precipitation that occurs on average once in 100 years

Percent Outwash

OUTWASH

Percentage of area of outwash

Percent Peat and Muck

MUCK

Percentage of area of peat and muck

End Moraines of Fine Textured Till

MORTILL

Percentage of End Moraines of Fine-Textured Till

Percent Medium Till

MEDTILL

Percentage of area of medium-textured glacial till

Percent Lacustrine Clay and Silt

PCLAY

Percentage of lacustrine clay and silt

Percent Thin Till over Bedrock

TILROCK

Percentage of area of thin glacial till over bedrock

Percent Coarse Till

CRSTILL

Percentage of area of coarse till

Abbrev Unit

(mi ) square miles

(ft/mi) feet per mi percent

(dim) dimensionless

(in) inches

Unit Types