KS FTFW MACY 10(2) FINAL Hydrology and Hydraulics Recommendations Report.pdf

KS FTFW MACY 10(2)

Entrance Road and Trails

Marais de Cygnes National Wildlife Refuge

Hydrology and Hydraulics

Recommendations Report

Federal Highway Administration

Central Federal Lands Highway Division

Prepared by

HDR Engineering, Inc.

May 8, 2020

Central Federal Lands | Hydrology and Hydraulics Recommendations Report hdrinc.com 1670 Broadway, Suite 3400, Denver, CO 80202-4824

(303) 764-1520

Table of Contents

1. Introduction

1.1 Project Description

1.2 Project Location

1.3 FEMA Compliance

1.4 Design Criteria

2. Hydrology

2.1 StreamStats Hydrology

2.2 Three-Variable Regression Equation Hydrology

3. Hydraulics

3.1 Model Approach

3.2 Key Assumptions

3.3 Computational Mesh

3.4 Elevation Data

3.5 Manning’s Roughness

3.6 Hydraulic Structures

3.7 Boundary Conditions

3.8 Model Results

3.9 Floodplain Impacts

4. Scour

4.1 Scour Analysis……………………………………………………………………………………………….… 22

4.2 Scour Countermeasure

5. Conclusion

6. References

7. Appendices……………………………………………………………………………………………32

Table of Figures

Figure 1. Project Location

Figure 2. Main Channel Drainage Basin Map

Figure 3. SRH-2D Computational Mesh and External Boundary Conditions

Figure 4. Topographic Data Extents

Figure 5. SRH-2D Materials Coverage

Figure 6. Existing Water Surface Elevations for 5-Year Design Event

Figure 7. Proposed Water Surface Elevations for 5-Year Design Event

Figure 8. Existing Water Surface Elevations for 100-Year Base Flood Event

Figure 9. Proposed Water Surface Elevations for 100-Year Base Flood Event

Figure 10. Water Surface Elevation Comparison for 100-Year Base Flood

Figure 11. Geotechnical Boring Locations

Figure 12. NCHRP Proposed Critical Velocities based on Erosion Potential

Figure 13. FHA Proposed Critical Shear Stresses based on Erosion Potential

Figure 14. 2D Model Results Profile

Figure 15. 25-Year Depth Profile along Proposed Structure

Figure 16. 25-Year Velocity Profile along Proposed Structure

Figure 17. Shear Stress Profile along Proposed Structure

Table of Tables

Table 1. StreamStats Peak Discharges Summary

Table 2. Regression Equation Parameters

Table 3. Main Channel Peak Flow Value Comparison

Table 4. Manning’s Roughness Coefficients

Table 5. Inflow and Outflow Boundary Condition Values

Table 6. Existing and Proposed Condition Model Results at Proposed Bridge Crossing

1. Introduction

1.1 Project Description

HDR is preparing a Project Delivery Plan for the Federal Highway Administration, Central Federal

Lands Highway Division (CFLHD) for proposed improvements to the Marias de Cygnes National

Wildlife Refuge (NWR) Entrance Road, Parking Area, and Refuge Orientation Trail located in Linn

County, Kansas. Construction improvements include clearing and grubbing, minor drainage structures, a pedestrian bridge, aggregate base, asphalt paving, and other minor safety improvements.

As part of the new “Refuge Orientation Trail” east of the US Fish & Wildlife Service (USFWS)

Headquarters, a 6-foot wide pedestrian bridge over an unnamed channel has been designed to allow visitors to cross the channel on site and better access the eastern portion of the refuge. This report serves as the basis for hydrologic and hydraulic analysis for the proposed pedestrian bridge and provides abutment scour countermeasure design recommendations.

1.2 Project Location

The proposed pedestrian bridge will cross the unnamed channel approximately 620 feet south of

Kansas State Highway 52 and approximately 585 feet southeast of the USFWS Visitor Center located at the end of Access Road. The project location is shown in Figure 1.

1.3 FEMA Compliance

Federal Emergency Management Agency (FEMA) has designated the special flood hazard area within the project site as a FEMA Zone A, as determined by the Flood Insurance Rate Map (FIRM)

#20107C0225C, effective date November 2, 2007, included in Appendix A. Floodplains designated as Zone A are areas subject to inundation by the 1-percent-annual-chance flood event generally determined using approximate methodologies and do not include Base Flood Elevations

(BFE) or flood depths. Linn County, in which the project site is located, participates in the National

Flood Insurance Program under the community identity 200194#.

FEMA regulations state that for Zone A floodplains, all cumulative impacts to the system from the time of the original study cannot result in a water surface elevation increase of more than one foot

(ft). These regulations are based on 44 Code of Federal Regulations (CFR) 60.3 (b). If exceeded, a Conditional Letter of Map Revision (CLOMR) is required. This analysis aims to address FEMA requirements under CFR 60.3 (b) by comparing existing and proposed water surface elevations over the floodplain for the 100-year flood discharge. A floodplain permit must also be obtained from the Kansas Department of Agriculture’s Division of Water Resources prior to any land disturbing activities.

Figure 1. Project Location

1.4 Design Criteria

The Kansas Department of Transportation (KDOT) Design Manual (KDOT, 2016) supplemented with Chapter 7 of the FLH "Project Development and Design Manual" (PDDM) are used as the basis to evaluate the proposed pedestrian bridge. Neither reference specifies design standards for a pedestrian bridge so the design team have met with the project constituents to agree upon standards applicable for this condition.

According to the criteria manuals, typical vehicular bridged waterways should be designed to the

50-year recurrence interval (2% annual exceedance probability [AEP]) for capacity with 2 feet of freeboard and the 100-year recurrence interval (1% AEP) for stability design. As agreed upon by the project constituents, since the proposed bridge will only be used for pedestrian traffic and not vehicular traffic, it will be designed to the 5-year recurrence interval (20% AEP) for capacity and the 10-year recurrence interval (10% AEP) for stability design. A scour check was also utilized with the 25-year recurrence interval (4% AEP).

Project Location

2. Hydrology

2.1 StreamStats Hydrology

Peak discharge rates for the 50-, 20-, 10-, 4- and 1-percent annual exceedance probabilities

(AEP) were determined using the USGS StreamStats web application. The calculations specific to Kansas are based on a study conducted by the USGS in cooperation with KDOT and the

Federal Emergency Management Agency (FEMA) to develop regression equations for peak streamflow of the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent AEP at ungaged locations in

Kansas (USGS, 2017). To develop a conservative hydrologic analysis, peak discharge rates were determined using the total area of Muddy Creek and the smaller tributary combining just upstream of proposed bridge location. According to the StreamStats reports, drainage areas for the Muddy

Creek and tributary are 2.09 mi2 and 0.06 mi2, respectively, for a combined area of 2.15 mi2.

StreamStats uses the following regression equations to calculate streamflows in this region of

Kansas as a function of contributing drainage area (CONTDA) and average 1981-2010 precipitation (PRECIPRIS10):

𝑄50% = 0.0018(𝐶𝑂𝑁𝑇𝐷𝐴)0.514(𝑃𝑅𝐸𝐶𝐼𝑃𝑅𝐼𝑆10)3.37

𝑄20% = 0.0269(𝐶𝑂𝑁𝑇𝐷𝐴)0.500(𝑃𝑅𝐸𝐶𝐼𝑃𝑅𝐼𝑆10)2.83

𝑄10% = 0.0955(𝐶𝑂𝑁𝑇𝐷𝐴)0.497(𝑃𝑅𝐸𝐶𝐼𝑃𝑅𝐼𝑆10)2.58

𝑄4% = 0.3311(𝐶𝑂𝑁𝑇𝐷𝐴)0.494(𝑃𝑅𝐸𝐶𝐼𝑃𝑅𝐼𝑆10)2.34

𝑄1% = 1.41(𝐶𝑂𝑁𝑇𝐷𝐴)0.490(𝑃𝑅𝐸𝐶𝐼𝑃𝑅𝐼𝑆10)2.06

A PRECIPRIS10 value of 42.5 inches was used based on the value outputted by StreamStats, as well as a contributing drainage area of 2.15 mi2.

Table 1 presents a summary of the StreamStats peak discharge values.

Table 1. StreamStats Peak Discharges Summary

AEP Flow Rate (cfs)

50% (2-yr) 820 20% (5-yr) 1600

10% (10-yr) 2220 4% (25-yr) 3120

1% (100-yr) 4640

2.2 Three-Variable Regression Equation Hydrology

In order to validate the peak discharges obtained from StreamStats, flows were also calculated using the three-variable regression equations presented in the KDOT Design Manual. According to the Design Manual, the regression equations “may be used as a check or comparison of the

USGS regression equations” and “should be used to compute design flows for drainage structures on unregulated rural streams with contributing drainage areas greater than 640 ac but less than

30 mi2” (KDOT, 2016). Due to the tributary drainage area being less than the range suggested, the equations were only applied to the main channel drainage basin.

The contributing area to the main channel just upstream of Highway 52 was delineated using the

ArcHydro toolset available within ArcGIS and a 1/9 arc-second 15 x 15 minute Digital Elevation

Model (DEM) published by the USGS in 2014. The delineated drainage basin is shown in Figure

2.

The parameters used by the three-variable regression equations include mean annual precipitation (P), drainage area (A), and a basin-average rainfall intensity (Ia) specific to each recurrence interval. The mean annual precipitation was obtained from Figure 11.3.1-1 in the

Design Manual, and drainage area was calculated based on the ArcHydro delineation. Basin-average rainfall intensities were calculated using equation 11-10 in the Design Manual which is a function of point rainfall intensity (obtained from KDOT’s Rainfall Intensity Tables for Counties in Kansas [KDOT, 2014]), drainage area, and a point rainfall reduction factor calculated based on time of concentration. Time of concentration for the watershed was calculated using equation 11-

2 for drainage areas with an impervious area ratio less than 0.03:

𝑇𝑐 = 0.0368 [ 𝐿

√𝑆𝐼

0.66 where: L = length of the longest flow path (ft/ft)

SI = average slope of the longest flow path (ft/ft), defined as the elevation difference between two points on the drainage path, located at 10% and

85% of the path length (measured from the design point), divided by the path length between the points (0.75L).

The longest flow path (with 10% and 85% of the path length indicated) is shown in Figure 2. An overview of the regression equation parameter values is presented in Table 2.

Table 2. Regression Equation Parameters

AEP P (in) A (mi2) Ia (in/hr)

50% (2-yr) 43 2.07 0.81 20% (5-yr) 43 2.07 1.04

10% (10-yr) 43 2.07 1.20 4% (25-yr) 43 2.07 1.42

1% (100-yr) 43 2.07 1.77

Table 3 provides a comparison of peak flow values calculated using each method. Note, the

StreamStats values shown in Table 3 are quantified upstream at Highway 52 at which is used as a discharge point for the culvert analysis.

Table 3. Main Channel Peak Flow Value Comparison

AEP StreamStats KDOT Regression

50% (2-yr) 808 cfs 491 cfs 20% (5-yr) 1,580 cfs 953 cfs

10% (10-yr) 2,190 cfs 1,314 cfs 4% (25-yr) 3,080 cfs 1,820 cfs

1% (100-yr) 4,580 cfs 2,592 cfs

As can be seen, the StreamStats values are consistently higher than the KDOT regression equation results. As such, the KDOT analysis was not performed for the larger basin area.

Therefore, the Stream Stats approach was applied and the results shown in Table 1 were applided to the proposed bridge hydraulic analysis in order to provide a conservative estimate of hydrologic conditions at the project site.

Service Layer Credits: Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community

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Proposed Bridge Location

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MAIN CHANNEL DRAINAGE BASIN MAP

FIGURE 2

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LEGEND

85% of Longest Flow Path 10% of Longest Flow Path Longest Flow Path Drainage Basin

3. Hydraulics

3.1 Model Approach

Sedimentation and River Hydraulics 2D model (SRH-2D), a two-dimensional depth-averaged numerical solver developed by the U.S. Bureau of Reclamation (USBR) (2008), was used to conduct the bridge waterway analysis for both the existing condition and proposed bridge configurations. Model inputs include a computational mesh to represent the topography, land cover characteristics of the project, discharge data, and boundary conditions.

A computational mesh was generated using aerial photography, land cover/land use data, topographic data, and project design files. The computational mesh includes more detail in areas of interest of hydraulic importance, such as in the vicinity of the bridge.

The best available elevation data was assigned to the mesh.

Spatial varying surface roughness information was incorporated into the model using aerial photographs.

The SRH-2D model was also used to compare 100-year (base flood) elevations for pre- and post-project conditions.

3.2 Key Assumptions

Every numeric model has limitations. The standard assumptions made in the formulation of a 2D, depth-averaged hydraulic model are appropriate to model the flow for this analysis. The assumptions include the following:

The vertical velocity component of the velocity field is small.

There is no hydrostatic pressure distribution.

The width of the flow field is large compared with the depth.

Velocity is not dependent on depth.

3.3 Computational Mesh

The computational mesh used is shown in Figure 3. The computational mesh is an unstructured mesh, which allows for the use of triangles and quadrilaterals, with variable element sizes.

Quadrilaterals were generally used for the channel areas and roadway. A combination of triangles and quadrilaterals were used in the floodplain. The proposed conditions mesh is equivalent to the existing conditions mesh except for slight changes at the bridge location to accommodate the addition of the bridge. Both meshes extend from approximately 720-ft upstream and 550-ft downstream of the proposed bridge location (measured along the main channel centerline). The

Highway 52 embankment and associated box culverts were not included in the final model mesh.

A discussion on this decision is included in the following sections.

3.4 Elevation Data

All elevation data is referenced to North American Vertical Datum of 1988 (NAVD88). The primary source of elevation data used for the hydraulic model is based on survey conducted by Woolpert, Inc. between 7/10/2019 – 7/13/2019. The extent of the surface generated from this survey data is shown in Figure 4. As the 2019 surface did not extend fully to the chosen upstream and downstream model limits, this surface was extended using the 2014 USGS 1/9 arc-second 15 x

15 minute DEM. For proposed model runs, the resulting terrain surface was manually adjusted to represent proposed grading in the vicinity of the bridge.

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SRH-2D COMPUTATIONAL MESH

FIGURE 3

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Computational Mesh Inflow BC 100-YR Inflow BC Downstream BC

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TOPOGRAPHIC DATA EXTENTS

FIGURE 4

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Legend Model Domain

2019 Survey DEM High : 811

Low : 781

2014 USGS DEM

High : 817

Low : 781

3.5 Manning’s Roughness

Surface roughness in the model, represented as Manning’s “n” values, was assigned spatially based on aerial imagery and confirmed during the site visit. The n values assigned are presented in Table 4, and shown spatially in Figure 5. Photos 1-4 were taken of the channel and floodplain conditions during the site visit.

Table 4. Manning’s Roughness Coefficients

Land Use Manning’s n

Main Channel 0.025 Open Water 0.06

Roadway 0.015 Developed Land/Gravel 0.035

High Grass 0.04 Floodplain – Timber/Brush 0.06

Photo 1. Proposed Bridge Location

Photo 2. Main Channel

Photo 3. Floodplain brush

Photo 4. High Grass

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SRH-2D MATERIALS COVERAGE

FIGURE 5

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Legend Land Cover

Developed Land/Gravel Floodplain - Timber/Brush High Grass Main Channel Open Water Roadway

3.6 Hydraulic Structures

An approximately 12’ x 8’ triple-box concrete culvert with flared wingwalls, shown in Photo 5, conveys flow from upstream of Kansas State Highway 52 to the main channel. Based on the results of a HY-8 culvert analysis (presented in Appendix C), it was determined that the culvert has sufficient capacity to convey flow for the 50, 20, 10, and 4 percent AEPs without overtopping.

Approximately 436 cfs overtops the highway during the 1 percent AEP. As a conservative analysis, the flood flows through the culverts and over the roadway were considered to rejoin immediately downstream of Highway 52.

Photo 5. Existing Culvert Structure Outlet

3.7 Boundary Conditions

For each model simulation, a single inflow boundary condition was defined based on the total inflow to the project site (refer back to Figure 3 for boundary condition locations). For the 50, 20, 10, and 4 percent AEPs, the main channel inflow (upstream) boundary condition arc was drawn based on the span of the existing culvert. For the 1 percent AEP, a longer main channel inflow boundary condition arc was drawn to correspond with the length of Highway 52 that would convey flow during overtopping (based on the overtopping water surface elevation outputted by HY-8).

Having the upstream boundary condition placed near the downstream face of the Highway 52 culverts provided consistent flow as utilizing the culverts and embankment upstream would likely show attenuation which would affect the hydrologic peak discharge assumptions. Values for the inflow and outflow (downstream) boundary conditions are summarized in Table 5.

Table 5. Inflow and Outflow Boundary Condition Values

AEP Inflow (cfs) Outflow WSEL (ft)

50% (2-yr) 820 792.0 20% (5-yr) 1,600 792.5

10% (10-yr) 2,220 793.0 4% (25-yr) 3,120 793.5

1% (100-yr) 4,640 794.5

For the proposed simulations, the pedestrian bridge was modeled as a single-span 60-ft long pressure flow bridge, with a 15.6–in superstructure and overtopping elevation of 795.1-ft.

3.8 Model Results

Results for the existing and proposed hydraulic model simulations are summarized in Table 6.

Figures 6 and 7 present water surface elevations for existing and proposed simulations, respectively, of the 5-year design storm. In Figure 7, the bridge location is seen where the dry land indicates the proposed pedestrian bridge abutments. Note that SRH-2D applies the 1-D weir equation to calculate an overtopping discharge, which is calculated separately from pressure flow and added into the solution at the downstream boundary condition arc. However, overtopping between the arcs is not shown in the 2-D results.

Based on the results shown, the proposed structure will be capable of passing the 20% AEP (5-year) design storm without overtopping.

Table 6. Existing and Proposed Condition Model Results at Proposed Bridge Crossing

AEP

Existing Water

Surface Elevation (ft) Proposed Water

Surface Elevation (ft) Bridge Low

Cord (ft) Proposed

Freeboard (ft)

50% 792.1 792.1 793.8 1.7

20% 793.4 793.3 793.8 0.5

10% 794.0 793.9 793.8 0

4% 794.6 794.6 793.8 0

1% 795.3 795.4 793.8 0

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5-YEAR EXISTING WATER SURFACE ELEVATION

FIGURE 6

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5-Year WSEL (ft) 790 - 791 791 - 792 792 - 793 793 - 794 794 - 795 795 - 796 796 - 797

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5-YEAR PROPOSED WATER SURFACE ELEVATION

FIGURE 7

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5-Year WSEL (ft) 790 - 791 791 - 792 792 - 793 793 - 794 794 - 795 795 - 796 796 - 797

3.9 Floodplain Impacts

Figures 8 and 9 present existing and proposed water surface elevations, respectively, for the 100-year base flood event. Figure 10 provides a comparison between the two (i.e. proposed minus existing). These results indicate that the proposed replacement would not result in a 1-ft increase in flood levels during the occurrence of the base flood discharge, and that a CLOMR will likely not be needed. A slight rise in water surface is observed to the east and west of the bridge, since the proposed embankment redirects more flow to these areas. Overall the average depth increase in the floodplain in the vicinity of the proposed pedestrian bridge is less than 1-ft which is allowable in the Zone A floodplain. Results of this analysis will be shared with the Linn County floodplain administrator in order to obtain the floodplain development permit.

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100-YEAR EXISTING WATER SURFACE ELEVATION

FIGURE 8

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100-Year WSEL (ft) 792 - 793 793 - 794 794 - 795 795 - 796 796 - 797 797 - 798 798 - 799 799 - 800 800 - 801 801 - 802 802 - 803

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100-YEAR PROPOSED WATER SURFACE ELEVATION

FIGURE 9

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100-Year WSEL (ft) 792 - 793 793 - 794 794 - 795 795 - 796 796 - 797 797 - 798 798 - 799 799 - 800 800 - 801 801 - 802 802 - 803

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100-YEAR WATER SURFACE ELEVATION COMPARISON

FIGURE 10

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Proposed - Existing WSEL (ft) < -1 -1 - -0.5 -0.5 - -0.25 -0.25 - -0.1 -0.1 - 0.1

0.1 - 0.25

0.25 - 0.5

0.5 - 1 > 1

4. Scour

4.1 Scour Analysis

Scour analyses are typically used to inform the structural design of a bridge and provide depths for countermeasure protection. However, based on the relatively shallow depth to bedrock at this location the cast-in-place concrete abutments will be supported on micropiles founded 10-feet into bedrock. Thus, the scour analysis simply provides estimates of scour parameters for the 10-year design and 25-year scour check flood frequencies.

The project geotechnical report was prepared by Shannon and Wilson, Inc. in November 2019.

Borings were taken at the three locations shown in Figure 11. SW-01 and SW-02 were taken outside of the stream channel but have been utilized to estimate subsurface conditions at the bridge opening. The depth to bedrock ranges between 9.4-12.5 feet for these two borings.

Figure 11. Geotechnical Boring Locations

The soil characteristics from bore SW-01, sample S-3 were assumed to be the most representative of native channel conditions since this was the deepest sample analyzed (9-feet).

The other two samples were taken at a depth of 1-foot and are more characteristic of surface conditions within the floodplain. The boring log results can be found in Appendix D. Overall the site mostly consists of lean clay which is considered a cohesive soil. The analysis techniques for scour in cohesive soil was followed.

At the project site, the following two scour mechanisms were evaluated:

Abutment Scour

Contraction Scour

Note that long-term scour was assumed to be negligible at this site since there is little evidence of any long term changes in sediment loading above, below, or in the vicinity of the bridge crossing. Steep cut banks exist along the channel but appear to be relatively stable. No evidence of signification aggradation or degradation was found in the project vicinity.

The first step of the cohesive soil scour analysis consists of estimating a critical velocity (VC), or a velocity at which soil erosion is initiated. Critical velocity was determined based on Figure 12 taken from the National Cooperative Highway Research Program (NCHRP) Report 24-15, titled

Abutment Scour in Cohesive Materials (NCHRP, 2009). SW-01, sample S-3 exhibited the properties of a high plasticity clay (Class IV). Thus, the minimum critical velocity shown for a high plasticity clay (and an erosion rate of 0.1 mm/hr, which is the recommended threshold for erosion) is approximately 1.5 m/s or 4.9 ft/s. Note that critical velocity also depends on flow depth, and so this value was compared to the equation for critical velocity provided in the FHA’s Scour in

Cohesive Soils publication (FHA, 2015) which computes VC as a function of flow depth.

Figure 12. NCHRP Proposed Critical Velocities based on Erosion Potential

Figure 6 of the FHA guidance provides an equation for a soil’s critical velocity based on a

Manning’s roughness coefficient, critical shear stress, and depth of flow. A Manning’s n value of

0.025 was assumed for the channel based on site visit photographs, and a critical shear stress of

10 Pa assumed based on Figure 13 taken from the FHA reference manual. A maximum flow depth of 10.5’ was used for the main channel based on the results of the 25-year model results, and a value of 2.0’ used for the toe of the abutment. This resulted in a critical velocity of 5.1 ft/s within the channel and 3.9 ft/s at the abutment.

Figure 13. FHA Proposed Critical Shear Stresses based on Erosion Potential

2D model results were taken along the bridge profile section shown in Figure 14. A maximum velocity of 4.3 ft/s is experienced within the main channel with a maximum velocity of 3.0 ft/s at the toe of the abutment for the 25-year event. This indicates that scour conditions are likely not present at the bridge crossing for recurrence intervals up to, and including, the 25-year event.

Figures 15 and 16 present flow depths and velocity profiles along the proposed structure for the

25-year scour check flood event, respectively.

Figure 14. 2D Model Results Profile (Contours Approximate)

Figure 15. 25-Year Depth Profile along Proposed Structure

Figure 16. 25-Year Velocity Profile along Proposed Structure

4.2 Scour Countermeasure

Based on the SRH-2D model results shown in Figure 17, a maximum shear stress of 0.21 psf is experienced during the 25-year event at the proposed structure. A Type 5.A permanent turf reinforcement mat (TRM) is recommended to protect against scour up to the 25-year scour check flood event. FHWA FP-03, Section 713 states that a Type 5.A specification is suitable for design shear stresses up to 6.0 psf (FHWA, 2003). The TRM is provided to stabilize all proposed grading associated with the bridge abutments as a measure of stability during and after construction while vegetation grows to suitable density.

Figure 17. Shear Stress Profile along Proposed Structure

5. Conclusion The purpose of this report is to provide a hydrologic and hydraulic analysis of the proposed pedestrian bridge to be located along the Marias de Cygnes NWR orientation trail, which includes:

selection of hydrologic peak discharges, proposed design hydraulic modeling, flood profile and floodplain analysis, and scour analysis.

Based on the hydraulic analysis, the proposed pedestrian bridge will be capable of passing the

5-year design event without overtopping. Additionally, the proposed encroachment by the bridge structure is unlikely to cause a rise in the base flood elevation greater than 1-ft due to the wide floodplain in this area, which allows the majority of flow to bypass the main channel for larger storm events. Since the modeled velocities within the channel and at the toe of the abutment have been shown to not exceed the critical velocities at these locations, there is limited potential for scour.

The conclusions and recommendations in this report are based on the conditions of the project site and the associated watershed at the time of this study. Any modifications to the site, man-made or natural, could alter the analysis, findings, and recommendations contained herein and could invalidate the analysis, findings, and recommendations. Site conditions, completion of upstream or downstream projects, upstream or downstream land use changes, climate changes, vegetation changes, maintenance practice changes, or other factors may change over time.

Additional analysis or updates may be required in the future as a result of these changes.

6. References Federal Highway Administration, 2009. “Bridge Scour and Stream Instability Countermeasures:

Experience, Selection, and Design Guidance (Volume 2)”. Third Edition. Publication No.

FHWA-NHI-09-112. Hydraulic Engineering Circular No. 23.

Federal Highway Administration, 2003. “Standard Specifications for Construction of Roads and

Bridges on Federal Highway Projects”. FP-03 U.S. Customary Units.

Federal Highway Administration, 2015. “Scour in Cohesive Soils”. Publication No. FHWA-HRT-

15-033.

Federal Lands Highway Division, 2012. "Project Development and Design Manual". Chapter 7

Hydrology and Hydraulics.

Kansas Department of Transportation Bureau of Road Design, 2016. “Design Manual”. Volume I

(Part C), Elements of Drainage & Culvert Design.

National Cooperative Highway Research Program (NCHRP), 2009. “Abutment Scour in Cohesive

Materials”. Report 24-15(2).

7. Appendices

Appendix A – FEMA FIRM

Appendix B – StreamStats Reports

Appendix C – HY-8 Analysis

Appendix D – Boring Logs

Appendix A

FEMA Firm

Appendix B

StreamStats Reports

9/10/2019 StreamStats https://streamstats.usgs.gov/ss/ 1/3

StreamStats Report

Basin Characteristics

Parameter Code Parameter Description Value Unit

CONTDA Area that contributes flow to a point on a stream 2.09 square miles

PRECPRIS10 Basin average mean annual precipitation for 1981 to 2010 from PRISM

42.5 inches

Peak-Flow Statistics Parameters[Peak Flow Region 1 2017 5063]

Region ID: KS Workspace ID: KS20190910142854695000 Clicked Point (Latitude, Longitude): 38.25814, -94.65426 Time: 2019-09-10 08:29:11 -0600 https://streamstats.usgs.gov/ss/ 2/3

Parameter Code Parameter Name Value Units

Min Limit

Max Limit

Parameter Code Parameter Name Value Units

Min Limit

Max Limit

CONTDA Contributing Drainage Area 2.09 square miles

0.17 15000

PRECPRIS10 Mean Annual Precip PRISM 1981

42.5 inches 15.3 47

Peak-Flow Statistics Flow Report[Peak Flow Region 1 2017 5063]

PIl: Prediction Interval-Lower, PIu: Prediction Interval-Upper, SEp: Standard Error of Prediction, SE:

Standard Error (other -- see report)

Statistic Value Unit SEp

2 Year Peak Flood 808 ft^3/s 49.9

5 Year Peak Flood 1580 ft^3/s 43.3

10 Year Peak Flood 2190 ft^3/s 43.6

25 Year Peak Flood 3080 ft^3/s 45.5

50 Year Peak Flood 3830 ft^3/s 48.4

100 Year Peak Flood 4580 ft^3/s 51.9

200 Year Peak Flood 5520 ft^3/s 55

500 Year Peak Flood 6760 ft^3/s 59.9

Peak-Flow Statistics Citations

Painter, C.C., Heimann, D.C., and Lanning-Rush, J.L.,2017, Methods for estimating annual exceedance-probability streamflows for streams in Kansas based on data through water year 2015: U.S. Geological Survey Scientific Investigations Report 2017–5063, 20 p.

(https://doi.org/10.3133/sir20175063)

USGS Data Disclaimer: Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty.

USGS Software Disclaimer: This software has been approved for release by the U.S. Geological Survey (USGS). Although the software has been subjected to rigorous review, the USGS reserves the right to update the software as needed pursuant to further analysis and review. No warranty, expressed or implied, is made by the USGS or the U.S. Government as to the functionality of the software and related material nor shall the fact of release constitute any such warranty. Furthermore, the software is released on condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from its authorized or unauthorized use.

https://doi.org/10.3133/sir20175063 https://streamstats.usgs.gov/ss/ 3/3

USGS Product Names Disclaimer: Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Application Version: 4.3.8 https://streamstats.usgs.gov/ss/ 1/3

StreamStats Report

Basin Characteristics

Parameter Code Parameter Description Value Unit

CONTDA Area that contributes flow to a point on a stream 0.06 square miles

PRECPRIS10 Basin average mean annual precipitation for 1981 to 2010 from PRISM

42.5 inches

Peak-Flow Statistics Parameters[Peak Flow Region 1 2017 5063]

Region ID: KS Workspace ID: KS20190910174721543000 Clicked Point (Latitude, Longitude): 38.25658, -94.65368 Time: 2019-09-10 11:47:36 -0600 https://streamstats.usgs.gov/ss/ 2/3

Parameter Code Parameter Name Value Units

Min Limit

Max Limit

Parameter Code Parameter Name Value Units

Min Limit

Max Limit

CONTDA Contributing Drainage Area 0.06 square miles

0.17 15000

PRECPRIS10 Mean Annual Precip PRISM 1981

42.5 inches 15.3 47

Peak-Flow Statistics Disclaimers[Peak Flow Region 1 2017 5063]

One or more of the parameters is outside the suggested range. Estimates were extrapolated with unknown errors

Peak-Flow Statistics Flow Report[Peak Flow Region 1 2017 5063]

Statistic Value Unit

2 Year Peak Flood 130 ft^3/s

5 Year Peak Flood 267 ft^3/s

10 Year Peak Flood 375 ft^3/s

25 Year Peak Flood 533 ft^3/s

50 Year Peak Flood 668 ft^3/s

100 Year Peak Flood 804 ft^3/s

200 Year Peak Flood 972 ft^3/s

500 Year Peak Flood 1200 ft^3/s

Peak-Flow Statistics Citations

Painter, C.C., Heimann, D.C., and Lanning-Rush, J.L.,2017, Methods for estimating annual exceedance-probability streamflows for streams in Kansas based on data through water year 2015: U.S. Geological Survey Scientific Investigations Report 2017–5063, 20 p.

(https://doi.org/10.3133/sir20175063)

USGS Data Disclaimer: Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty.

USGS Software Disclaimer: This software has been approved for release by the U.S. Geological Survey (USGS). Although the software has been subjected to rigorous review, the USGS reserves the right to update the software as needed pursuant to further analysis and review. No warranty, expressed or implied, is made by the USGS or the U.S. Government as to the https://doi.org/10.3133/sir20175063 https://streamstats.usgs.gov/ss/ 3/3 functionality of the software and related material nor shall the fact of release constitute any such warranty. Furthermore, the software is released on condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from its authorized or unauthorized use.

USGS Product Names Disclaimer: Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Application Version: 4.3.8

Appendix C

HY-8 Analysis

Table 1 - Summary of Culvert Flows at Crossing: KS-52

Headwater Elevation (ft) Discharge Names Total Discharge

(cfs) Existing Triple Box

Discharge (cfs) Roadway

Discharge (cfs) Iterations

789.21 2-Year 820.00 820.00 0.00 1

791.48 5-Year 1600.00 1600.00 0.00 1

793.11 10-Year 2220.00 2220.00 0.00 1

795.48 25-Year 3120.00 3120.00 0.00 1

798.75 100-Year 4640.00 4203.79 436.11 6

796.40 Overtopping 3444.18 3444.18 0.00 Overtopping

Rating Curve Plot for Crossing: KS-52

Table 2 - Culvert Summary Table: Existing Triple Box

Straight Culvert

Inlet Elevation (invert): 785.40 ft, Outlet Elevation (invert): 784.80 ft

Culvert Length: 60.00 ft, Culvert Slope: 0.0100

Discharge Names

Total Discharge

(cfs)

Culvert Discharge

(cfs) Headwater

Elevation (ft) Inlet Control

Depth (ft) Outlet Control

Depth (ft) Flow Type

Normal Depth

(ft) Critical

Depth (ft) Outlet

Depth (ft) Tailwater Depth (ft)

Outlet Velocity

(ft/s)

Tailwater Velocity

(ft/s) 2-Year 820.00 820.00 789.21 3.812 2.092 1-S2n 1.783 2.526 2.010 0.000 11.330 0.000 5-Year 1600.00 1600.00 791.48 6.081 3.977 1-S2n 2.801 3.944 3.253 0.000 13.663 0.000 10-Year 2220.00 2220.00 793.11 7.707 5.526 1-S2n 3.520 4.906 4.125 0.000 14.950 0.000 25-Year 3120.00 3120.00 795.48 10.085 8.887 5-S2n 4.491 6.156 5.281 0.000 16.412 0.000 100-Year 4640.00 4203.79 798.75 13.345 11.528 5-S2n 5.593 7.509 6.557 0.000 17.809 0.000

Water Surface Profile Plot for Culvert: Existing Triple Box

Site Data - Existing Triple Box

Site Data Option: Culvert Invert Data

Inlet Station: 0.00 ft

Inlet Elevation: 785.40 ft

Outlet Station: 60.00 ft

Outlet Elevation: 784.80 ft

Number of Barrels: 3

Culvert Data Summary - Existing Triple Box

Barrel Shape: Concrete Box

Barrel Span: 12.00 ft

Barrel Rise: 8.00 ft

Barrel Material: Concrete

Embedment: 0.00 in

Barrel Manning's n: 0.0150

Culvert Type: Straight

Inlet Configuration: 1:1 Bevel (45º flare) Wingwall

Inlet Depression: None

Tailwater Channel Data - KS-52

Tailwater Channel Option: Enter Constant Tailwater Elevation

Constant Tailwater Elevation: 784.80 ft

Roadway Data for Crossing: KS-52

Roadway Profile Shape: Constant Roadway Elevation

Crest Length: 40.00 ft

Crest Elevation: 796.40 ft

Roadway Surface: Paved

Roadway Top Width: 50.00 ft

Appendix D

Boring Logs

R -1

R -2

S -1

S -2

S -3

D ur in g

D ril lin g

Medium stiff to stiff, gray-brown to brown, Lean Clay (CL); moist; trace to few sand, iron oxide staining, carbonaceous fragments. [A-7-6]

Medium stiff, gray-brown to brown, Fat Clay (CH); moist; few sand, trace gravel. [A-7-6]

LIMESTONE: medium strong, light gray, laminated, massive (Tacket Formation).

BOTTOM OF BORING

COMPLETED ON 8/7/19

7.0

12.5

22.5

FIG. A-3

S am pl es

4 in.

AWJ

Automatic

0 60

Total Depth:

Top Elevation:

Vert. Datum:

Horiz. Datum:

Ground Water Level ATD

Geotechnical and Environmental Consultants

SHANNON & WILSON, INC.

103390-001

22.5 ft.

20 40

SSA & Rock Core IPES, Inc.

CME 45C Track Rig

LEGEND

Drilling Method:

Drilling Company:

Drill Rig Equipment:

Other Comments:

LOG OF BORING SW-01

20 40 60 80

Sample Not Recovered

Hole Diam.:

Rod Type.:

Hammer Type:

G ro un d

W at er

D ep th , f t.

Standard Penetration Test

Rock Core

S ym bo l

Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between material types, and the transition may be gradual.

SOIL DESCRIPTION

Northing:

Easting:

Station:

Offset:

NOTES

1. Refer to Figures A-1 and A-2 for explanation of symbols, codes, abbreviations and definitions.

2. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.

3. Groundwater level, if indicated above, is for the date specified and may vary.

4. USCS designation is based on visual-manual classification and selected lab testing.

KS FTFW MACY 10(2)

Marais de Cygnes NWR

Linn County, Kansas

D ep th , f t.

November 2019

QCL 3

M A

S T

E R

_L O

G _E

_P O

C K

E T

P E

N

-0

M A

R A

IS

D

E C

Y G

N E

S .G

P J

1/

/1

Recovery (%)

Plastic Limit

% Fines (<0.075mm)

Liquid Limit

(use scale at top) % Water Content

RQD (%)

PENETRATION RESISTANCE

Hammer Wt. & Drop: 140 lbs / 30 inches

(blows/foot)

DRAFT

S

S -2

S -3

D ur in g

D ril lin g

Soft to medium stiff, gray-brown to brown, Lean Clay (CL); moist; trace sand, iron oxide staining, carbonaceous fragments. [A-6]

- Auger refusal on bedrock encountered at 9.4 feet

BOTTOM OF BORING

COMPLETED ON 8/7/19

9.4

FIG. A-4

S am pl es

4 in.

AWJ

Automatic

20 40 60

0 60

Total Depth:

Top Elevation:

Vert. Datum:

Horiz. Datum:

Ground Water Level ATD

Geotechnical and Environmental Consultants

SHANNON & WILSON, INC.

103390-001

9.4 ft.

20 40

Solid-Stem Auger IPES, Inc.

CME 45C Track Rig

LEGEND

Drilling Method:

Drilling Company:

Drill Rig Equipment:

Other Comments:

LOG OF BORING SW-02

Sample Not Recovered

Hole Diam.:

Rod Type.:

Hammer Type:

G ro un d

W at er

D ep th , f t.

Standard Penetration Test

S ym bo l

Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between material types, and the transition may be gradual.

SOIL DESCRIPTION

Northing:

Easting:

Station:

Offset:

NOTES

1. Refer to Figures A-1 and A-2 for explanation of symbols, codes, abbreviations and definitions.

2. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.

3. Groundwater level, if indicated above, is for the date specified and may vary.

4. USCS designation is based on visual-manual classification and selected lab testing.

KS FTFW MACY 10(2)

Marais de Cygnes NWR

Linn County, Kansas

D ep th , f t.

November 2019

QCL 3

M A

S T

E R

_L O

G _E

_P O

C K

E T

P E

N

-0

M A

R A

IS

D

E C

Y G

N E

S .G

P J

1/

/1

PENETRATION RESISTANCE

Hammer Wt. & Drop: 140 lbs / 30 inches

(blows/foot)

(<0.075mm)

Liquid Limit Natural Water Content

% Fines % Water Content

Plastic Limit

50/4"

S

B -1

S -2

G ro un dw at er

N ot

E nc ou nt er ed

D ur in g

D ril lin g.6.0 inches of crushed limestone aggregate

Medium stiff to stiff, gray-brown to brown to dark brown, Fat Clay (CH); moist; few sand, trace gravel. [A-7-6]

BOTTOM OF BORING

COMPLETED ON 8/7/19

0.5

5.5

FIG. A-5

S am pl es

4 in.

AWJ

Automatic

20 40 60

0 60

Total Depth:

Top Elevation:

Vert. Datum:

Horiz. Datum:

Geotechnical and Environmental Consultants

SHANNON & WILSON, INC.

103390-001

5.5 ft.

20 40

Solid-Stem Auger IPES, Inc.

CME 45C Track Rig

LEGEND

Drilling Method:

Drilling Company:

Drill Rig Equipment:

Other Comments:

LOG OF BORING SW-03

Sample Not Recovered

Hole Diam.:

Rod Type.:

Hammer Type:

G ro un d

W at er

D ep th , f t.

Standard Penetration Test

Grab Sample

S ym bo l

Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between material types, and the transition may be gradual.

SOIL DESCRIPTION

Northing:

Easting:

Station:

Offset:

NOTES

1. Refer to Figures A-1 and A-2 for explanation of symbols, codes, abbreviations and definitions.

2. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.

3. Groundwater level, if indicated above, is for the date specified and may vary.

4. USCS designation is based on visual-manual classification and selected lab testing.

KS FTFW MACY 10(2)

Marais de Cygnes NWR

Linn County, Kansas

D ep th , f t.

November 2019

QCL 3

M A

S T

E R

_L O

G _E

_P O

C K

E T

P E

N

-0

M A

R A

IS

D

E C

Y G

N E

S .G

P J

1/

/1

PENETRATION RESISTANCE

Hammer Wt. & Drop: 140 lbs / 30 inches

(blows/foot)

(<0.075mm)

Liquid Limit Natural Water Content

% Fines % Water Content

Plastic Limit

LL=68

KS FTFW MACY 10(2)

Marais de Cygnes NWR

DRAFT Geotechical Design ReportTable B-1 - Summary of Laboratory Test Results

STRENGTH

Gravel Sand Fines Liquid Limit

Plastic Limit

Plasticity Index pH Resistivity Sulfates Chlorides

Unconfined Compressive

Strength Top Bottom (%) (%) (%) (%) (ohm-cm) (%) (%) (psi)

S-1 1.0 2.5 16.5 6.2 2,121 0.001 0.0002

S-2 4.0 5.5 CL A-7-6 20.2 95 49 15 34

S-3 9.0 10.5 CH A-7-6 23.5 0 14 86 54 18 36

R-2 18.5 19.2 4,698

S-1 1.0 2.5 CL A-6 15.9 0 4 96 34 19 15

S-2 4.0 5.5 CL A-6 25.0 96 37 20 17

S-3 9.0 9.4 23.3 7.0 1,772 0.007 0.0004

B-1 1.0 4.0 CH A-7-6 23.6 3 7 90 68 17 51

S-1 1.0 2.5 21.1 S-2 4.0 5.5 23.1

NOTES:

Sample Depth (feet)

1 Refer to Appendix A, Figure A-1 for definitions.

2 Gravel defined as particles larger than the No. 10 sieve size, Sand as particles between the No. 10 and No. 200 sieve sizes, and Fines as particles passing the No. 200 sieve.

USCS

Symbol¹

AASHTO

Soil

Classification

CORROSIONGRAIN SIZE ANALYSIS²SAMPLE DATA ATTERBERG LIMITS

SW-01

SW-02

SW-03

Water ContentBoring

103390-001 Page 1 of 1 103390-001_T1 - 11/24/2019

6 4

P E

R C

E N

T F

IN

E

R B

Y W

E

IG

H T

PL

3/

CH

CL

CH

Fat Clay; few sand [A-7-6]

Lean Clay; trace sand [A-6]

Fat Clay; few sand, trace gravel [A-7-6]

23.5

15.9

23.6

COARSE MEDIUM

GRAVEL

.3

2 1

5/

HYDROMETER ANALYSIS

3/

U.S.C.S.

SYMBOL

.0

1/

.0

12 20

86.3

95.7

90.4

.0

NAT.

W.C. %

FINE

GRAIN SIZE IN MILLIMETERS

.0

1/

.0 6.8

.0

LL

.0

.0

.0

9.0

1.0

1.0

DEPTH

(feet) KS FTFW MACY 10(2)

Marais de Cygnes NWR Linn County, Kansas

.1

.0

November 2019

.0

COBBLES

.4

1/

GRAIN SIZE DISTRIBUTION

SW-01, S-3

SW-02, S-1

SW-03, B-1

SAMPLE ID

Geotechnical and Environmental Consultants

.6

SHANNON & WILSON, INC.

.0

PI

.0

P E

R C

E N

T C

O A

R S

E R

B Y

W E

IG

H

T

.0

.0

SAND

FINES

HDR Engineering, Inc.

SIZE OF MESH OPENING IN INCHES

.0

.0

.0

SIEVE ANALYSIS

.0

.2

.0

GRAIN SIZE IN MILLIMETERS

103390-001

G S

A _M

A

IN

103390 -00

1 M A

R A

IS

D

E C

Y G

N E

S .G

P J C

LO

N

E F

R O

M T

H

IS

P R

O

JE

C T

.G P

J 11/22/19

.0

.0

FINES: SILT OR CLAY

NO. OF MESH OPENINGS PER INCH, U.S. STANDARD

FIG. B-1

SAMPLE

DESCRIPTION

COARSE FINE

.0

FIG

. B

0 10 20 30 40 50 60 70 80 90 100 110

November 2019

CL:

CH:

ML or OL:

MH or OH:

CL-ML:

PASS.

#200, %

CHCL

ML or OL

P

LA

S T

IC

IT

Y I

N D

E X

P

I

CL

CH

CL

CL

CH

U.S.C.S.

SYMBOL

LEGEND

Low plasticity inorganic clays; sandy and silty clays

High plasticity inorganic clays

Inorganic and organic silts and clayey silts of low plasticity

Inorganic and organic silts and clayey silts of high plasticity

Silty clays and clayey silts

SAMPLE ID

4.0

9.0

1.0

4.0

1.0

DEPTH

(feet)

FIG

. B

-2 SHANNON & WILSON, INC.

Geotechnical and Environmental Consultants

20.2

23.5

15.9

25.0

23.6

MH or OH

NAT.

W.C. %

SOIL

CLASSIFICATION

SW-01, S-2

SW-01, S-3

SW-02, S-1

SW-02, S-2

SW-03, B-1

103390-001

94.9

86.3

95.7

96.4

90.4

KS FTFW MACY 10(2)

Marais de Cygnes NWR

Linn County, Kansas

PLASTICITY CHART

LIQUID LIMIT - LL (%)

PI

A T

T _M

A

IN

390-001 M

A R

A

IS

D E

C Y

G N

E S

.G P

J S H

A N

_W

IL.G

D T

1/22/19

PL

LL

HDR Engineering, Inc.

Lean Clay; few sand [A-7-6]

Fat Clay; few sand [A-7-6]

Lean Clay; trace sand [A-6]

Lean Clay; trace sand [A-6]

Fat Clay; few sand, trace gravel [A-7-6]

FIG. B-2

CL-ML DRAFT