OK_ERFO_500(1)_Horton_Slough_Final_Hydraulics_Report.pdf

Horton Slough Trail U.S. Fish and Wildlife Service

Sequoyah County, OK

OK ERFO T500(1)

Final Hydraulic Report

Federal Highway Administration Central Federal Lands Highway Division

February 2021

Executive Summary

Hydrologic and hydraulic analyses were conducted for the OK ERFO T500(1) Horton Slough Trail Project.

The project proposes to replace the failed pedestrian crossing over Horton Slough with a pre-fabricated structure. For the pedestrian bridge the 10-year flood and 25-year flood were selected as the hydraulic design and check floods, respectively. The peak flow values were estimated using USGS regression equations for Oklahoma. Existing and proposed conditions two-dimensional hydraulic modeling using SRH-2D was conducted to estimate water surface elevations and flow velocities at the project site. Bridge scour will be evaluated in subsequent design phases when geotechnical information is available. Based on the results of the hydraulic analysis the following proposed bridge geometry was selected:

Proposed Bridge Recommendations

Parameter Recommended Value Design Frequency 10-year

Design Flow 1,570 cfs Bridge Low Chord Elevation 467.6 ft. NAVD88

Bridge Waterway Opening Width 150 ft.

Scour depth estimates were conducted in accordance with HEC-18 using a 25-year scour design flood and 50-year scour check flood, and the 100-year flood for reference. Scour elevation results are summarized in the following table:

Summary of Bridge Scour Results

Parameter 25-Year 50-Year 100-Year

Total Scour Depth (ft) 1.0 1.2 1.6 Abutment Elevation (ft) 460.0 460.0 460.0

Potential Scour Elevation (ft) 459.0 458.8 458.4 i OK ERFO T500(1) Horton Slough Trail - Hydraulic Report

Table of Contents

1 Project Background Information

2 Hydraulic Design Criteria

3 Hydrology

3.1 Hydrologic Setting

3.2 FEMA Flood Insurance Study

3.3 Available Hydrologic Data

3.4 Regression Equation Estimates

3.5 Rainfall-Runoff Model Estimates

3.5.1 Precipitation

3.5.2 Basin Parameters

3.6 Recommended Design Discharges

4 Hydraulic Analysis

4.1 Topographic Information

4.2 Hydraulic Model Development

4.3 Hydraulic Model Results

4.3.1 Existing Conditions

4.3.2 Proposed Conditions

4.4 Scour Assessment

4.4.1 Long Term Stability Assessment

4.4.2 Geotechnical Investigation

4.4.3 Scour Estimates

5 Recommendations

6 References ii OK ERFO T500(1) Horton Slough Trail - Hydraulic Report

Tables Table 1: PDDM Hydraulic Design Criteria Table 2: Horton Slough Project Hydraulic Design Criteria Table 3: Horton Slough Bridge Basin Properties Table 4: Available Peak Streamflow Information Table 5: StreamStats Peak Discharge Estimates at Project Location Table 6: NOAA Atlas 14 24-Hour Point Precipitation – Horton Slough Table 7: Basin Parameters (NRCS Method) Table 8: HEC-HMS Peak Discharge Estimates at Project Site Table 9: Recommended Design Flows Table 10: Project Land Cover Types and Manning’s Roughness Table 11: Existing Conditions Hydraulic Results Table 12: Proposed Conditions Hydraulic Results Table 13: Proposed Conditions Freeboard Table 14: Proposed vs Existing 100-Year Water Surface Elevations Table 15: Contraction Scour Estimates Table 15: Proposed Bridge Recommendations

Figures

Figure 1: Project location map Figure 2: Horton Slough Drainage Basin Figure 3: FEMA National Flood Hazard Layer – FIRM Excerpt Figure 4: Project Topographic Surface, Elevations in feet referenced to NAVD88 Figure 5: Flow vs. Depth Rating Curve Boundary Condition Figure 6: Project Land Cover Types and Manning’s Roughness Figure 7: Proposed WSEL Results at Bridge Location Figure 8: Boring Sample BH20-02 Particle Size Distribution

Appendices

Appendix A: Hydrologic Analyses Appendix B: Hydraulic Analyses

Page 1 OK ERFO T500(1) Horton Slough Trail - Hydraulic Report

1 PROJECT BACKGROUND INFORMATION

The Horton Slough Trail project is located in Sequoyah County, OK within the U.S. Fish and Wildlife Service (FWS) Sequoyah National Wildlife Refuge, see Figure 1. As a result of the May 2019 flood event the site experienced flood damage at various locations including the failure of the existing pedestrian suspension bridge over Horton Slough. The proposed project will replace the bridge crossing with a pre-fabricated structure and improved foundations.

Figure 1: Project location map.

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2 HYDRAULIC DESIGN CRITERIA

The Federal Lands Highway Project Development and Design Manual (PDDM) (Federal Lands Highway 2012) establishes the hydraulic design criteria for highway bridges but it does not provide specific requirement for pedestrian bridges. The PDDM standard design criteria are listed in Table 1.

Table 1: PDDM Hydraulic Design Criteria

Bridges:

Design Frequency Check Frequency Freeboard

50-year flood Greater of 100-year or overtopping flood

• Minimum of 2 feet

• 3.5 feet to 5 feet when woody debris potential is significant

• 5 feet to 10 feet when ice flow potential is significant

Scour:

Scour Design

Frequency Scour Check Frequency Scour Countermeasure Design Frequency

100-year flood 200-year flood 200-year flood Floodplain Encroachment

FEMA SFHA Involvement Allowable Rise Project within FEMA regulated special flood hazard area (SFHA) – Zone A Maximum 1-foot rise in water surface profile over existing conditions

Since the proposed bridge will be only used for pedestrian travel on the Horton Slough trail the hydraulic criteria shown in Table 2 was applied to the project.

Table 2: Horton Slough Project Hydraulic Design Criteria

Bridges:

Design Frequency Check Frequency Freeboard

10-year flood Greater of 25-year or overtopping flood • Minimum of 2 feet

Scour:

Scour Design

Frequency Scour Check Frequency Scour Countermeasure Design Frequency

25-year flood 50-year flood 50-year flood Floodplain Encroachment

FEMA SFHA Involvement Allowable Rise Project within FEMA regulated special flood hazard area (SFHA) – Zone A Maximum 1-foot rise in base flood over existing conditions

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3 HYDROLOGY

3.1 HYDROLOGIC SETTING

The project is located within the Pheasant Creek-Arkansas River Sub-watershed (HUC12:) on Horton Slough. Horton Slough provides a hydraulic connection between Sally Jones Lake and the Robert S. Kerr Reservoir, all of which are man-made features. The Robert S. Kerr reservoir impounds the Arkansas River at Robert S. Kerr Lock and Dam. The total drainage area to the dam is approximately 148,800 square miles.

The Sally Jones Lake-Horton Slough drainage basin was delineated using available 10-meter digital elevation model (DEM) information obtained from the USGS National Map as shown in Figure 2. Surface waters are delivered to the lake by various intermittent streams. Reverse flow from the reservoir depending to the lake has been noted in the past depending on reservoir water levels. For the purposes of the bridge replacement project and in order to be conservative it was assumed that Horton Slough is the only outflow from Sally Jones Lake and that flow direction takes place from Sally Jones Lake eastward to the Robert S. Kerr Reservoir. It is outside of the scope of the project to simulate Arkansas River hydraulics, reservoir operations and flow reversals in the slough. A summary of general basin properties is shown in Table 3.

Figure 2: Horton Slough Drainage Basin

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Table 3: Horton Slough Bridge Basin Properties

Stream Crossing Description

Drainage Area (mi2)

Mean Basin Elevation (ft)

Mean Basin

Slope (%)

Mean Annual Precipitation

(in)

Stream Slope 10 and 85 Method

(ft/mi) Horton Slough

Pedestrian Bridge 5.25 511 5.4 46.6 3.4

3.2 FEMA FLOOD INSURANCE STUDY

According to FEMA Flood Insurance Rate Map (FIRM) panel 40135C0380F the project is located within the FEMA Zone A special flood hazard area (SFHA). The SFHA comprises the land area that is shown in the FIRM as being inundated by the 1% chance (100-year) base flood and where the National Flood Insurance Program's (NFIP) floodplain management regulations apply. The boundaries of FEMA Zone A are determined using approximate methods therefore no base flood elevations (BFEs) are shown in the FIRM.

An excerpt of the applicable FIRM is shown in Figure 3. In this case the Zone A boundaries appear to be the Arkansas River floodplain. The bridge trail project will not cause adverse impacts to base flood elevations in the river. As shown in Table 2 the PDDM criteria for Zone A allows a maximum of 1-foot rise in proposed conditions base flood elevations when compared to the existing condition.

Figure 3: FEMA National Flood Hazard Layer – FIRM Excerpt

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3.3 AVAILABLE HYDROLOGIC DATA

There are no active USGS peak streamflow stations within the project limits. The closest USGS active station is located in the Arkansas River approximately 10 miles downstream of the project site. Although listed as an active station the period of record for peak streamflow data is limited. Due to the size of the project drainage basin compared to the Arkansas River basin the streamflow information was not used in the hydrology analysis for the project. Table 4 summarizes the station location and period of record.

Table 4: Available Peak Streamflow Information

USGS

Station Location Latitude Longitude Drainage

Area Period of Record

Total Years Status

07246500 Arkansas

River near Sallisaw, OK

35°20'59" 94°46'16" 143,729 mi2 1927 - 1970 32 Inactive

3.4 REGRESSION EQUATION ESTIMATES

The StreamStats web application (U.S. Geological Survey 2016) was used to estimate peak flows for the Horton Slough Bridge. The Oklahoma StreamStats application uses the regression equations presented in USGS Report 2010-5137 (Lewis 2010). The statewide equations developed for Oklahoma relate peak discharge to drainage area, mean annual precipitation, and stream slope. According to the study the average standard errors of prediction for the equations vary from 32 to 47 percent. The results for the Horton Slough Bridge basin are shown in Table 5.

Table 5: StreamStats Peak Discharge Estimates at Project Location

Percent Chance Exceedance (%)

Return Period (year)

Horton Slough Bridge Peak Flow (cfs)

20 5 1,130 10 10 1,570 4 25 2,260 2 50 2,870 1 100 3,490

3.5 RAINFALL-RUNOFF MODEL ESTIMATES

3.5.1 Precipitation

The point precipitation values for the project were obtained from NOAA Atlas 14 Volume 8 (Perica, et al.

2013) using the Precipitation Frequency Data Server (National Oceanic and Atmospheric Administration 2011). The project is located in climate region 4 according to Figure 4.1.2 in Atlas 14 which encompasses the Mississippi Valley from eastern Oklahoma to the Gulf of Mexico.

The values of point precipitation are assumed to represent precipitation over the entire project area.

NOAA Atlas 14 states that point precipitation values within the project area are equal to point rainfall values. The point precipitation/rainfall values for a duration of 24 hours and various return periods are shown in Table 6.

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Table 6: NOAA Atlas 14 24-Hour Point Precipitation – Horton Slough

Percent Chance Exceedance (%)

Return Period (year)

Point Precipitation (inches)

20 5 4.83 10 10 5.55 4 25 6.63 2 50 7.52 1 100 8.48

3.5.2 Basin Parameters

The NRCS curve number (CN) method (Natural Resources Conservation Service 1997) was used to estimate runoff. A composite CN for the basin was estimated using SSURGO soil information (Natural Resources Conservation Service 2015) and the 2011 national land cover dataset (Multi-Resolution Land Characteristics Consortium 2018). Soils within the project basin are classified predominately as hydrologic soil groups (HSG) B and D. Land cover for the project basins consists primarily of deciduous forest, pasture, cultivated crops, and woody wetlands. The NRCS lag time equation and unit hydrograph were used to estimate peak flows from the basins. An SCS (now NRCS) Type 2 rainfall distribution was selected based on the project location. A summary of basin parameters is shown in Table 7.

Table 7: Basin Parameters (NRCS Method)

Basin Parameter Value Drainage Area (sq. mi.) 5.55

Composite Curve Number (CN) 70 Watershed Slope (%) 5.4

Watershed Length (ft) 27,300 NRCS Lag Time (min) 154

The hydrologic computations were carried out using HEC-HMS (U.S. Army Corps of Engineers 2017). The results for various return periods are shown in Table 8.

Table 8: HEC-HMS Peak Discharge Estimates at Project Site

Percent Chance Exceedance (%)

Return Period (year)

Cushing Creek Peak Flow (cfs)

20 5 1,141 10 10 1,491 4 25 2,048 2 50 2,527 1 100 3,058

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3.6 RECOMMENDED DESIGN DISCHARGES

The recommended design flows for the Horton Slough Bridge are shown in Table 9. The regression equation results were selected since they are more conservative than the rainfall-runoff model results for the less frequent events. Additional details of the hydrologic analysis are provided in Appendix A.

Table 9: Recommended Design Flows

Percent Chance Exceedance (%)

Return Period (year)

Horton Slough Bridge Peak Flow (cfs)

20 5 1,130 10 10 1,570 4 25 2,260 2 50 2,870 1 100 3,490

4 HYDRAULIC ANALYSIS

4.1 TOPOGRAPHIC INFORMATION

Two sources of topographic information were used to develop the hydraulic model: 2010 LiDAR-derived 1-meter bare earth digital elevation model (DEM) obtained from the USGS National Map (U.S. Geological Survey 2018) and field survey information collected by Central Federal Lands in the vicinity of the existing bridge and in selected cross section locations. The field survey was limited to overbank areas except at a location approximately 1,300 feet downstream of the proposed bridge where channel thalweg information was collected at the existing fisherman’s crossing. Since LiDAR information does not capture the bathymetry of the main channel, a channel cross section was estimated using information obtained from the field survey. The cross section shape, width, and depth were approximated using the field survey information. The estimated bathymetry of the main channel was incorporated into the project LiDAR topographic data by using the channel stamping methodology in SMS 13.0.11 (Aquaveo 2019). A main channel slope of 0.03% was assumed based on the valley slope.

The field survey information was merged with the LiDAR data to obtain a seamless topographic surface for the project as shown in Figure 4. All elevations for the study are in units of feet and are referenced to the North American Vertical Datum of 1988 (NAVD 88).

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Figure 4: Project Topographic Surface, Elevations in feet referenced to NAVD88

4.2 HYDRAULIC MODEL DEVELOPMENT

Two-dimensional hydraulic modeling using SRH-2D (U.S. Bureau of Reclamation 2017) was conducted to estimate water surface elevations, water depth and flow velocities in the project reach. The model pre-and post-processing was performed using the SMS 13.0.11 interface (Aquaveo 2019). The model domain extends approximately 700 feet upstream (west) of the proposed bridge crossing, or approximately 400 feet east of Sally Jones Lake. The model extends approximately 2,700 feet downstream of the proposed bridge to avoid influencing waters surface elevations at the project site. Due to the topography at the model domain boundary it was not possible to capture the entirety of the flow for the less frequent events. A wall boundary condition is assumed at the southern boundary where flow appears to continue south outside of the model domain boundary toward the Arkansas River. It is outside of the scope of the project to model the entire lake and Arkansas River watershed.

The upstream boundary conditions in the model were specified as a steady inflow discharge using the peak flows in Table 9. As mentioned previously it was assumed for the study that the entire contributing

Horton Slough Bridge

Page 9 OK ERFO T500(1) Horton Slough Trail - Hydraulic Report basin outlets via Horton Slough. The downstream boundary condition was specified as a stage-discharge rating curve obtained using Manning’s equation and a energy grade line slope of 0.1% as shown in Figure 5.

Figure 5: Flow vs. Depth Rating Curve Boundary Condition

SRH-2D uses Manning’s “n” values to calculate bed friction. The land use types were delineated from aerial imagery as shown in Figure 6 and assigned typical roughness values. The roughness values used in the model are shown in Table 10.

Table 10: Project Land Cover Types and Manning’s Roughness

Land Use Manning's "n" Main Channel 0.035

Floodplain Pasture 0.030 Floodplain Trees 0.100

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Figure 6: Project Land Cover Types and Manning’s Roughness

4.3 HYDRAULIC MODEL RESULTS

4.3.1 Existing Conditions

Existing conditions hydraulic simulations using the parameters described in Section 4.2 were conducted for the 5-, 10-, 25-, 50-, and 100-year return periods. The failed existing bridge was excluded from the analysis since there were no bridge geometry details available. The existing conditions results are summarized in Table 11. Velocity values were extracted inside the bridge opening. Water surface elevation and depth values were extracted at a point approximately 160 feet upstream from the bridge site. The N4520 Road bridge was modeled as a blocked obstruction to simulate backwater effects.

Additional details of the hydraulic analyses are provided in Appendix B.

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Table 11: Existing Conditions Hydraulic Results

Return Period (year) Velocity (ft/s) Depth (ft) WSEL (ft)

Average Maximum Average Maximum Average Maximum 5 1.7 2.8 4.4 6.4 462.79 462.81

10 1.9 3.1 4.7 7.4 463.84 463.85 25 2.1 3.5 5.3 8.8 465.22 465.23 50 2.1 3.7 6.0 9.9 466.28 466.29

100 2.1 4.0 6.7 10.8 467.19 467.21

4.3.2 Proposed Conditions

Proposed conditions hydraulic simulations using the parameters described in Section 4.2 were conducted for the 5-, 10-, 25-, 50-, and 100-year return periods. For the proposed conditions model the proposed bridge was assumed to have a low chord elevation of 467.6 feet and a bridge opening of approximately 150 feet. The proposed bridge was modeled in SRH-2D as a pressure flow boundary conditions for the 50- , and 100-year simulations. The proposed conditions results are summarized in Table 12. Velocity values were extracted inside the bridge opening. Water surface elevation and depth values were extracted at a point approximately 160 feet upstream from the bridge site. The results show that the proposed bridge has capacity to pass a 10-year peak flow while meeting the minimum of 2 feet of freeboard. The proposed bridge has capacity to pass a 25-year peak flow with less than 1 foot of freeboard. Bridge pressure flow, where the flow impinges on the low chord, occurs at a 50-year peak flow and above. The proposed bridge does not experience overtopping for the events simulated. The proposed bridge results are shown graphically in Figure 7. Additional details of the hydraulic analyses are provided in Appendix B.

Table 12: Proposed Conditions Hydraulic Results

Return Period (year) Velocity (ft/s) Depth (ft) WSEL (ft)

Average Maximum Average Maximum Average Maximum 5 1.7 2.8 3.5 6.3 462.73 462.74

10 1.9 3.1 4.7 7.4 463.84 463.85 25 2.2 3.5 5.3 8.8 465.22 465.23 50 2.5 3.8 6.0 9.9 466.28 466.34

100 2.6 4.2 6.7 10.8 467.20 467.26

Freeboard was evaluated for the maximum water surface elevation at a point approximately 160 feet upstream of the bridge face. The results are summarized in Table 13. The results show the proposed bridge can pass the 10-year design frequency with 3.78 feet of freeboard and a 100-year design frequency with

0.37 feet of freeboard.

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Table 13: Proposed Conditions Freeboard

Return Period (year) Proposed

Bridge Low Chord (ft)

Maximum WSEL (ft)

Freeboard (ft)

5 467.63 462.74 4.89 10 467.63 463.85 3.78 25 467.63 465.23 2.40 50 467.63 466.34 1.29

100 467.63 467.26 0.37

Figure 7: Proposed WSEL Results at Bridge Location

A comparison of the average and maximum 100-year water surface elevations upstream of the bridge is shown in Table 14. The results show that the increase in 100-year water surface elevation is caused by the proposed bridge is not significant. Since the bridge causes a rise in base flood elevations of less than 1-foot the floodplain encroachment criteria for FEMA Zone A is satisfied.

Table 14: Proposed vs Existing 100-Year Water Surface Elevations

Return Period (year) WSEL (ft)

Average Maximum Existing 100-year 467.19 467.21

Proposed 100-year 467.20 467.26 Difference (Proposed – Existing) 0.01 0.05

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4.4 SCOUR ASSESSMENT

4.4.1 Long Term Stability Assessment

As described in previous sections, Horton Slough provides a hydraulic connection between Sally Jones Lake and the Robert S. Kerr Reservoir, all of which are man-made features. Flow and flow direction in Horton Slough vary with water levels in the connecting lakes. For this evaluation flow was assumed to primarily take place from Sally Jones Lake to the reservoir, or west to east. As shown in Table 12, stream velocities for the design events are extremely low, varying from approximately 2 to 4 feet per second. For mean annual conditions stream velocity and sediment transport capacity are expected to be low. There is no evidence of lateral migration or vertical degradation at the site, the slough is a straight channel within the vicinity of the project, only showing sinuosity downstream of the county road bridge. To account for uncertainty in the evaluation, 1-foot of long term degradation is assumed in the following scour assessment.

4.4.2 Geotechnical Investigation

A gradation analysis of streambed material was conducted as part of the geotechnical investigation documented in the project Geotechnical Report. Based on the laboratory results the sample is classified as SP-SM or a poorly graded sand with silt. The median particle size (D50) is 0.2 mm (0.0006 ft). The particle size distribution is shown in Figure 8.

Figure 8: Boring Sample BH20-02 Particle Size Distribution

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4.4.3 Scour Estimates

Scour depth estimates were conducted in accordance with HEC-18 (Federal Highway Administration 2012). Total scour is the combination of long term degradation, contraction scour and local scour. For this study local scour was estimated using the NCHRP 24-20 method. As discussed previously, the site investigation did not observe potential for long term degradation. For this analysis, 1-foot of long term degradation was assumed to account for potential bed elevation changes.

Based on the hydraulic design criteria established for the project, scour depths were estimated using the a 25-year scour design flood and 50-year scour check flood. In addition, 100-year scour depths were estimated. Based on the critical velocity of the streambed materials a live bed scour condition can be expected. In this condition sediment is being transported into the bridge opening from upstream flow.

Abutment scour was estimated using the NCHRP 24-20 method which applies an amplification factor to the contraction scour at the abutments, i.e. it includes contraction scour at each abutment as part of the estimate. For this estimate, scour elevations are referenced to the bottom of the abutment pile cap. A summary of potential contraction and abutment scour estimates are shown in Table 15. A minimum median size of 0.0007 feet was used in the abutment scour analysis per HEC-18. This provides a conservative estimate as smaller particle sizes tend to limit ultimate scour depths due to cohesion. Note that these results are maximum potential depths and assume that the entire depth is allowed to scour.

The ultimate scour depth could be limited by soil layers not represented by the geotechnical boring sample. Additional details of the scour assessment are included in Appendix B.

Table 15: Contraction Scour Estimates

Parameter 25-Year 50-Year 100-Year

D50 (ft) 0.0007 Average Flow Depth Upstream of

Contraction(ft) 7.6 4.0 4.0

Critical Velocity (ft/s) 1.4 5.3 5.3 Average Velocity Upstream (ft/s) 3.3 7.5 7.5

Scour Condition Live Bed Live Bed Live Bed Main Channel Contraction Scour Depth (ft) 0.0 0.0 0.1

Abutment Scour Depth (ft) 0.0 0.2 0.6 Long Term Degradation (ft) 1.0 1.0 1.0

Total Scour Depth (ft) 1.0 1.2 1.6 Abutment Elevation (ft) 460.0 460.0 460.0

Potential Scour Elevation (ft) 459.0 458.8 458.4

Class 1 riprap is recommended for abutment slope protection based on HEC-23 Design Guideline 14 (Federal Highway Administration 2009).

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5 RECOMMENDATIONS

Hydrology and hydraulics analyses were conducted for the Horton Slough bridge location. Based on the hydraulic results minimum values shown in Table 16 are recommended.

Table 16: Proposed Bridge Recommendations

Parameter Recommended Value Design Frequency 10-year

Design Flow 1,570 cfs Bridge Low Chord Elevation 467.6 ft NAVD88

Bridge Waterway Opening Width 150 ft

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6 REFERENCES

Aquaveo. 2019. Surface-water Modeling System (SMS), version 13.0.5. Provo, UT.

Federal Highway Administration . 2009. "Bridge Scour and Stream Instability Countermeasures - Experience, Selection, and Design Guidelines, Hydraulic Engineering Circular No. 23, Third Edition, FHWA-NHI 09-111 (Vol. 1), FHWA-NHI-09-112 (Vol. 2)." Federal Highway Administration, Washington, DC.

Federal Highway Administration. 2012. "Evaluating Scour at Bridges, Hydraulic Engineering Circular No.

18, Fifth Edition, FHWA-HIF-12-003." Washington D.C.

Federal Lands Highway. 2012. "Project Development and Design Manual, Chapter 7 Hydrology and Hydraulics." https://flh.fhwa.dot.gov/resources/design/pddm/.

Lewis, Jason M. 2010. "Methods for Estimating the Magnitude and Frequency of Peak Streamflows for Unregulated Streams in Oklahoma." U.S. Geological Survey Scientific Investigations Report 2010- 5137. https://pubs.usgs.gov/sir/2010/5137/.

Multi-Resolution Land Characteristics Consortium . 2018. National Land Cover Database 2011 (NLCD 2011). Multi-Resolution Land Characteristics Consortium (MRLC).

https://data.nal.usda.gov/dataset/national-land-cover-database-2011-nlcd-2011.

National Oceanic and Atmospheric Administration. 2011. Precipitation Frequency Data Server (PFDS).

Silver Springs, MD. Accessed April 2019. https://hdsc.nws.noaa.gov/hdsc/pfds/index.html.

Natural Resources Conservation Service. 1997. "National Engineering Handbook, Part 630 Hydrology."

Washington, DC. https://directives.sc.egov.usda.gov/viewerFS.aspx?hid=21422.

Natural Resources Conservation Service. 2015. Soil Survey Geographic (SSURGO) database. Fort Worth, TX. Accessed April 2019. http://websoilsurvey.nrcs.usda.gov.

Perica, Sanja, Deborah Martin, Sandra Pavlovic, Ishani Roy, Michael St. Laurent, Carl Trypaluk, Dale Unruh, Michael Yekta, and Geoffrey Bonnin. 2013. "Precipitation Frequency Atlas of the United States Volume 8 Version 2.0: Midwestern States (Colorado, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Oklahoma, South Dakota, Wisconsin)." NOAA Atlas 14, Silver Spring, MD.

U.S. Army Corps of Engineers. 2017. HEC-HMS, Hydrologic Engineering Center Hydrologic Modeling System. Version 4.2.1. Davis, CA.

U.S. Bureau of Reclamation. 2017. SRH-2D, Sedimentation and River Hydraulics – Two-Dimensional model.

Version 3.2.

U.S. Geological Survey. 2016. StreamStats Program. http://streamstats.usgs.gov.

U.S. Geological Survey. 2018. The National Map. Accessed March 2019.

https://viewer.nationalmap.gov/advanced-viewer/.

OK ERFO 500(1) Horton Slough Bridge - Hydraulic Report

Appendix A – Hydrologic Analyses

5/15/2020 StreamStats https://streamstats.usgs.gov/ss/ 1/4

Horton Slough - StreamStats Report

Basin Characteristics

Parameter Code Parameter Description Value Unit

APRAVPRE Mean April Precipitation 4.25 inches

BSLDEM10M Mean basin slope computed from 10 m DEM 5.4 percent

CANOPY_PCT Percentage of drainage area covered by canopy as described in OK SIR 2009_5267

26.31 percent

CONTDA Area that contributes flow to a point on a stream 5.25 square miles

CSL10_85fm Change in elevation between points 10 and 85 percent of length along main channel to basin divide divided by length between points ft per mi

3.36 feet per mi

Region ID: OK Workspace ID: OK20200515205347019000 Clicked Point (Latitude, Longitude): 35.45121, -94.98005 Time: 2020-05-15 14:54:01 -0600 https://streamstats.usgs.gov/ss/ 2/4

Parameter Code Parameter Description Value Unit

DAUNREG Unregulated drainage area used in OK regulated equations 5.25 square miles

DECAVPRE Mean December Precipitation 3.15 inches

ELEV Mean Basin Elevation 511 feet

FEBAVPRE Mean February Precipitation 2.64 inches

IMPNLCD01 Percentage of impervious area determined from NLCD 2001 impervious dataset

0.14 percent

JUNAVPRE Mean June Precipitation 4.79 inches

LC01DEV Percentage of land-use from NLCD 2001 classes 21-24 2.4 percent

MARAVPRE Mean March Precipitation 4.29 inches

MAYAVPRE Mean May Precipitation 5.65 inches

NRCSPCT Percent of contributing drainage area regulated by NRCS floodwater-retarding structures

0 percent

OUTLETELEV Elevation of the stream outlet in thousands of feet above

NAVD88.

466 feet

PRECIP Mean Annual Precipitation 46.56 inches

PRECIPOUT Mean annual precip at the stream outlet (based on annual PRISM precip data in inches from 1971-2000)

46.59 inches

PREG_06_10 Mean precipitation at gaging station location for June to October summer period

19.9 inches

PREG_11_05 Mean monthly precipitation for November through May at the stream outlet

26.7 inches

SOILPERM Average Soil Permeability 2.56 inches per hour

Peak-Flow Statistics Parameters[Peak Statewide Unregulated 2010 5137]

Parameter Code Parameter Name Value Units

Min Limit

Max Limit

CONTDA Contributing Drainage Area 5.25 square miles

0.1 2510 https://streamstats.usgs.gov/ss/ 3/4

Parameter Code Parameter Name Value Units

Min Limit

Max Limit

CSL10_85fm Stream Slope 10 and 85 Method ft per mi

3.36 feet per mi 1.98 342

PRECIP Mean Annual Precipitation 46.56 inches 16.6 62.1

Peak-Flow Statistics Parameters[Peak Statewide NRCS Regulated 2010 5137]

Parameter Code Parameter Name Value Units

Min Limit

Max Limit

DAUNREG Unregulated Drainage Area 5.25 square miles

0.1 2510

CSL10_85fm Stream Slope 10 and 85 Method ft per mi

3.36 feet per mi 1.98 342

PRECIP Mean Annual Precipitation 46.56 inches 16.6 62.1

Peak-Flow Statistics Flow Report[Peak Statewide Unregulated 2010 5137]

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

Standard Error (other -- see report)

Statistic Value Unit SEp Equiv. Yrs.

2 Year Peak Flood 634 ft^3/s 46.7 2

5 Year Peak Flood 1130 ft^3/s 35.1 5

10 Year Peak Flood 1570 ft^3/s 31.8 8

25 Year Peak Flood 2260 ft^3/s 34.7 9

50 Year Peak Flood 2870 ft^3/s 34 11

100 Year Peak Flood 3490 ft^3/s 35.7 12

500 Year Peak Flood 5360 ft^3/s 43.3 12

Peak-Flow Statistics Flow Report[Peak Statewide NRCS Regulated 2010 5137]

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

Standard Error (other -- see report)

Statistic Value Unit SEp Equiv. Yrs.

Controlled 2 Year Peak Flood 634 ft^3/s 46.7 2

Controlled 5 Year Peak Flood 1130 ft^3/s 35.1 5

Controlled 10 Year Peak Flood 1570 ft^3/s 31.8 8

Controlled 25 Year Peak Flood 2260 ft^3/s 34.7 9 https://streamstats.usgs.gov/ss/ 4/4

Statistic Value Unit SEp Equiv. Yrs.

Controlled 50 Year Peak Flood 2870 ft^3/s 34 11

Controlled 100 Year Peak Flood 3490 ft^3/s 35.7 12

Controlled 500 Year Peak Flood 5360 ft^3/s 43.3 12

Peak-Flow Statistics Citations

Lewis, J.M.,2010, Methods for estimating the magnitude and frequency of peak streamflows for unregulated streams in Oklahoma: U.S. Geological Survey Scientific Investigations Report SIR 2010-5137, 41 p. (http://pubs.usgs.gov/sir/2010/5137/)

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Application Version: 4.3.11 http://pubs.usgs.gov/sir/2010/5137/

5/4/2020 Precipitation Frequency Data Server https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=35.5015&lon=-94.9346&data=depth&units=english&series=pds 1/4

NOAA Atlas 14, Volume 8, Version 2 Location name: Vian, Oklahoma, USA*

Latitude: 35.5015°, Longitude: -94.9346° Elevation: 564.23 ft**

* source: ESRI Maps ** source: USGS

POINT PRECIPITATION FREQUENCY ESTIMATES

Sanja Perica, Deborah Martin, Sandra Pavlovic, Ishani Roy, Michael St. Laurent, Carl Trypaluk, Dale Unruh, Michael Yekta, Geoffery Bonnin

NOAA, National Weather Service, Silver Spring, Maryland

PF_tabular | PF_graphical | Maps_&_aerials

PF tabular PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)1

Duration Average recurrence interval (years)

1 2 5 10 25 50 100 200 500 1000

5-min 0.435 (0.355‑0.532)

0.496 (0.404‑0.607)

0.594 (0.483‑0.728)

0.674 (0.546‑0.828)

0.783 (0.620‑0.978)

0.867 (0.676‑1.09)

0.949 (0.724‑1.21)

1.03 (0.765‑1.34)

1.14 (0.823‑1.51)

1.22 (0.867‑1.63)

10-min 0.637 (0.520‑0.779)

0.726 (0.592‑0.888)

0.869 (0.707‑1.07)

0.987 (0.800‑1.21)

1.15 (0.908‑1.43)

1.27 (0.989‑1.60)

1.39 (1.06‑1.78)

1.51 (1.12‑1.97)

1.67 (1.21‑2.21)

1.79 (1.27‑2.39)

15-min 0.777 (0.634‑0.950)

0.885 (0.722‑1.08)

1.06 (0.863‑1.30)

1.20 (0.976‑1.48)

1.40 (1.11‑1.75)

1.55 (1.21‑1.95)

1.70 (1.29‑2.17)

1.84 (1.37‑2.40)

2.04 (1.47‑2.69)

2.18 (1.55‑2.92)

30-min 1.13 (0.923‑1.38)

1.29 (1.05‑1.58)

1.55 (1.26‑1.90)

1.77 (1.43‑2.17)

2.05 (1.62‑2.56)

2.27 (1.77‑2.86)

2.48 (1.89‑3.18)

2.70 (2.00‑3.50)

2.97 (2.15‑3.93)

3.18 (2.26‑4.25)

60-min 1.49 (1.22‑1.83)

1.72 (1.41‑2.11)

2.09 (1.70‑2.56)

2.38 (1.93‑2.93)

2.78 (2.19‑3.46)

3.07 (2.39‑3.86)

3.36 (2.56‑4.29)

3.64 (2.70‑4.72)

4.00 (2.89‑5.29)

4.26 (3.03‑5.71)

2-hr 1.86 (1.53‑2.25)

2.15 (1.77‑2.61)

2.62 (2.15‑3.18)

3.00 (2.45‑3.65)

3.50 (2.79‑4.32)

3.87 (3.04‑4.82)

4.23 (3.25‑5.35)

4.58 (3.42‑5.90)

5.03 (3.65‑6.59)

5.35 (3.83‑7.11)

3-hr 2.10 (1.74‑2.52)

2.43 (2.01‑2.93)

2.96 (2.45‑3.58)

3.39 (2.79‑4.11)

3.97 (3.18‑4.88)

4.40 (3.47‑5.46)

4.82 (3.72‑6.07)

5.23 (3.92‑6.71)

5.76 (4.20‑7.52)

6.14 (4.41‑8.13)

6-hr 2.56 (2.14‑3.05)

2.92 (2.44‑3.49)

3.53 (2.95‑4.22)

4.04 (3.35‑4.84)

4.74 (3.85‑5.80)

5.29 (4.22‑6.52)

5.84 (4.55‑7.32)

6.40 (4.85‑8.17)

7.15 (5.27‑9.29)

7.72 (5.59‑10.1)

12-hr 3.09 (2.61‑3.65)

3.45 (2.91‑4.08)

4.09 (3.44‑4.84)

4.66 (3.91‑5.53)

5.50 (4.54‑6.72)

6.19 (5.01‑7.62)

6.92 (5.47‑8.66)

7.70 (5.91‑9.81)

8.80 (6.56‑11.4)

9.67 (7.06‑12.6)

24-hr 3.58 (3.06‑4.19)

4.03 (3.44‑4.72)

4.83 (4.11‑5.66)

5.55 (4.70‑6.53)

6.63 (5.53‑8.05)

7.52 (6.16‑9.20)

8.48 (6.77‑10.5)

9.52 (7.37‑12.0)

11.0 (8.26‑14.1)

12.2 (8.94‑15.7)

2-day 4.04 (3.48‑4.68)

4.69 (4.04‑5.44)

5.82 (5.00‑6.76)

6.81 (5.83‑7.93)

8.23 (6.91‑9.88)

9.39 (7.74‑11.3)

10.6 (8.52‑13.0)

11.9 (9.25‑14.9)

13.6 (10.3‑17.4)

15.0 (11.1‑19.3)

3-day 4.41 (3.83‑5.08)

5.12 (4.44‑5.90)

6.34 (5.48‑7.32)

7.41 (6.38‑8.57)

8.96 (7.57‑10.7)

10.2 (8.47‑12.3)

11.5 (9.32‑14.1)

12.9 (10.1‑16.1)

14.9 (11.3‑18.9)

16.4 (12.2‑21.0)

4-day 4.75 (4.14‑5.45)

5.46 (4.75‑6.27)

6.69 (5.81‑7.69)

7.77 (6.72‑8.96)

9.36 (7.95‑11.1)

10.7 (8.87‑12.8)

12.0 (9.76‑14.7)

13.5 (10.6‑16.7)

15.5 (11.8‑19.6)

17.1 (12.8‑21.8)

7-day 5.63 (4.95‑6.41)

6.31 (5.54‑7.18)

7.49 (6.56‑8.54)

8.55 (7.46‑9.78)

10.1 (8.68‑12.0)

11.4 (9.60‑13.6)

12.8 (10.5‑15.5)

14.3 (11.3‑17.7)

16.4 (12.6‑20.6)

18.1 (13.6‑22.9)

10-day 6.38 (5.63‑7.21)

7.05 (6.22‑7.98)

8.24 (7.25‑9.34)

9.29 (8.15‑10.6)

10.9 (9.34‑12.7)

12.1 (10.2‑14.4)

13.5 (11.1‑16.3)

15.0 (11.9‑18.4)

17.0 (13.1‑21.3)

18.6 (14.1‑23.5)

20-day 8.38 (7.48‑9.38)

9.23 (8.23‑10.3)

10.6 (9.46‑11.9)

11.8 (10.5‑13.3)

13.5 (11.7‑15.6)

14.8 (12.6‑17.2)

16.1 (13.3‑19.1)

17.5 (14.0‑21.2)

19.3 (15.0‑23.9)

20.8 (15.8‑26.0)

30-day 10.0 (9.01‑11.2)

11.1 (9.96‑12.4)

12.8 (11.5‑14.3)

14.2 (12.7‑15.9)

16.1 (13.9‑18.3)

17.5 (14.9‑20.2)

18.9 (15.6‑22.2)

20.2 (16.2‑24.3)

22.0 (17.1‑27.0)

23.3 (17.8‑29.1)

45-day 12.2 (11.0‑13.4)

13.5 (12.2‑15.0)

15.7 (14.1‑17.4)

17.4 (15.6‑19.4)

19.6 (17.1‑22.2)

21.3 (18.2‑24.3)

22.8 (19.0‑26.6)

24.3 (19.5‑28.9)

26.1 (20.3‑31.8)

27.4 (21.0‑33.9)

60-day 14.0 (12.7‑15.4)

15.7 (14.2‑17.2)

18.2 (16.5‑20.1)

20.3 (18.2‑22.4)

22.8 (19.9‑25.7)

24.7 (21.2‑28.1)

26.4 (22.1‑30.7)

28.1 (22.7‑33.3)

30.1 (23.5‑36.4)

31.4 (24.1‑38.8)

1 Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS).

Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values.

Please refer to NOAA Atlas 14 document for more information.

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PF graphical https://www.commerce.gov/ http://www.noaa.gov/ https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=35.5015&lon=-94.9346&data=depth&units=english&series=pds 2/4

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Maps & aerials

Small scale terrain https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=35.5015&lon=-94.9346&data=depth&units=english&series=pds 3/4

Large scale terrain

Large scale map

Large scale aerial

3km

2mi

100km

60mi

100km

60mi https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=35.5015&lon=-94.9346&data=depth&units=english&series=pds 4/4

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US Department of Commerce National Oceanic and Atmospheric Administration

National Weather Service National Water Center

1325 East West Highway Silver Spring, MD 20910

Questions?: HDSC.Questions@noaa.gov

Disclaimer

100km

60mi https://www.commerce.gov/ http://www.noaa.gov/ http://www.nws.noaa.gov/ http://www.nws.noaa.gov/oh/ mailto:HDSC.Questions@noaa.gov http://www.nws.noaa.gov/disclaimer.html

National Land Cover Dataset - USGS National Map (U.S. Geological Survey 2018)

Horton Slough HEC-HMS Information

Model Input:

Model Results:

Horton Slough HEC-HMS Information (cont.)

Horton Slough HEC-HMS Information (cont.)

OK ERFO 500(1) Horton Slough Bridge - Hydraulic Report

Appendix B - Hydraulic Analyses

B.1 Existing Conditions SRH-2D Results

Model domain and computational mesh

5-Year Existing Conditions Water Surface Elevation

10-Year Existing Conditions Water Surface Elevation

25-Year Existing Conditions Water Surface Elevation

50-Year Existing Conditions Water Surface Elevation

100-Year Existing Conditions Water Surface Elevation

B.2 Proposed Conditions SRH-2D Results

5-Year Proposed Conditions Water Surface Elevation

10-Year Proposed Conditions Water Surface Elevation

25-Year Proposed Conditions Water Surface Elevation

50-Year Proposed Conditions Water Surface Elevation

100-Year Proposed Conditions Water Surface Elevation

Bridge Scour Analysis: 25-Year Bridge Scour Analysis Notes

Main Channel Contraction Scour Contraction & Long Term Scour is applied method due to greater scour.

Local Scour at Abutments Left Abutment Abutment Scour Method: NCHRP Method Abutment Scour Depth -0.07 ft Total Scour at Abutment 0.00 ft Total Scour Elevation at Abutment Right Abutment Abutment Scour Method: NCHRP Method Abutment Scour Depth -0.07 ft Total Scour at Abutment 0.00 ft Total Scour Elevation at Abutment

Main Channel Contraction Scour

Contraction Scour

Computation Type: Clear-Water or Live-Bed Scour Input Parameters Average Depth Upstream of Contraction: 7.57 ft D50: 0.000700 ft Average Velocity Upstream: 3.33 ft/s Results of Scour Condition Critical velocity above which bed material of size D and smaller will be transported: 1.39 ft/s Contraction Scour Condition: Live-Bed Live Bed and/or Clear Water Input Parameters Temperature of Water: 60.00 ºF Slope of Energy Grade Line at Approach Section: 0.0004 ft/ft Flow in Contracted Section: 2003.48 cfs Flow Upstream that is Transporting Sediment: 2077.33 cfs Width in Contracted Section: 83.15 ft Width Upstream that is Transporting Sediment: 82.45 ft Depth Prior to Scour in Contracted Section: 7.53 ft Unit Weight of Water: 62.40 lb/ft^3 Unit Weight of Sediment: 165.00 lb/ft^3 Results of Live Bed Method Shear Velocity: 0.32 ft/s Fall Velocity: 0.09 ft/s Average Depth in Contracted Section after Scour: 7.29 ft Scour Depth for Live Bed: -0.24 ft Scour may be limited by armoring. Compute all methods to check.

Left Bank Contraction Scour

Input Parameters Average Depth Upstream of Contraction: 2.55 ft D50: 0.000000 ft Average Velocity Upstream: 1.54 ft/s Results of Scour Condition Critical velocity above which bed material of size D and smaller will be transported: 0.00 ft/s Contraction Scour Condition: Live-Bed Live Bed and/or Clear Water Input Parameters Temperature of Water: 60.00 ºF Slope of Energy Grade Line at Approach Section: 0.0004 ft/ft Flow in Contracted Section: 163.58 cfs Flow Upstream that is Transporting Sediment: 100.55 cfs Width in Contracted Section: 21.63 ft Width Upstream that is Transporting Sediment: 25.66 ft Depth Prior to Scour in Contracted Section: 3.60 ft Unit Weight of Water: 62.40 lb/ft^3 Unit Weight of Sediment: 165.00 lb/ft^3

Right Bank Contraction Scour

Input Parameters Average Depth Upstream of Contraction: 3.99 ft D50: 0.000000 ft Average Velocity Upstream: 1.24 ft/s Results of Scour Condition Critical velocity above which bed material of size D and smaller will be transported: 0.00 ft/s Contraction Scour Condition: Live-Bed Live Bed and/or Clear Water Input Parameters Temperature of Water: 60.00 ºF Slope of Energy Grade Line at Approach Section: 0.0004 ft/ft Flow in Contracted Section: 96.68 cfs Flow Upstream that is Transporting Sediment: 126.51 cfs Width in Contracted Section: 37.35 ft Width Upstream that is Transporting Sediment: 25.60 ft Depth Prior to Scour in Contracted Section: 3.64 ft

Left Abutment Details

Abutment Scour

Computation Type: NCHRP Input Parameters

NCHRP Method Abutment Type: Vertical-wall abutment Angle of Embankment to Flow: 92.32 Degrees Centerline Length of Embankment: 0.00 ft Projected Length of Embankment: 0.00 ft Width of Flood Plain: 0.00 ft Unit Discharge, Upstream in Main Channel (q1): 25.20 cfs/ft Unit Discharge in the Constricted Area (q2): 24.07 cfs/ft D50: 0.000700 ft Upstream Flow Depth: 7.57 ft Flow Depth Prior to Scour: 8.80 ft Result Parameters q2/q1: 0.96 Average Velocity Upstream: 3.33 ft/s Critical Velocity above which Bed Material of Size D and Smaller will be Transported: 1.39 ft/s Scour Condition: Live Bed Embankment Length/Floodplain Width Ratio: 0.00 Scour Condition: a (Main Channel) Amplification Factor: 1.20 Flow Depth including Contraction Scour: 7.28 ft Maximum Flow Depth including Abutment Scour: 8.73 ft Scour Hole Depth from NCHRP Method: -0.07 ft

Right Abutment Details

Angle of Embankment to Flow: 87.68 Degrees Centerline Length of Embankment: 0.00 ft Projected Length of Embankment: 0.00 ft Width of Flood Plain: 0.00 ft Unit Discharge, Upstream in Main Channel (q1): 25.20 cfs/ft Unit Discharge in the Constricted Area (q2): 24.07 cfs/ft D50: 0.000700 ft Upstream Flow Depth: 7.57 ft Flow Depth Prior to Scour: 8.80 ft Result Parameters q2/q1: 0.96 Average Velocity Upstream: 3.33 ft/s Critical Velocity above which Bed Material of Size D and Smaller will be Transported: 1.39 ft/s Scour Condition: Live Bed Embankment Length/Floodplain Width Ratio: 0.00 Scour Condition: a (Main Channel) Amplification Factor: 1.20 Flow Depth including Contraction Scour: 7.28 ft Maximum Flow Depth including Abutment Scour: 8.73 ft Scour Hole Depth from NCHRP Method: -0.07 ft

Bridge Scour Analysis: 50-Year Bridge Scour Analysis

Main Channel Contraction Scour Contraction & Long Term Scour is applied method due to greater scour.

Local Scour at Abutments Left Abutment Abutment Scour Method: NCHRP Method Abutment Scour Depth 0.16 ft Total Scour at Abutment 0.16 ft Total Scour Elevation at Abutment Right Abutment Abutment Scour Method: NCHRP Method Abutment Scour Depth 0.16 ft Total Scour at Abutment 0.16 ft

Input Parameters Average Depth Upstream of Contraction: 8.62 ft D50: 0.000700 ft Average Velocity Upstream: 3.62 ft/s Results of Scour Condition Critical velocity above which bed material of size D and smaller will be transported: 1.42 ft/s Contraction Scour Condition: Live-Bed Live Bed and/or Clear Water Input Parameters Temperature of Water: 60.00 ºF Slope of Energy Grade Line at Approach Section: 0.0010 ft/ft Flow in Contracted Section: 2457.73 cfs Flow Upstream that is Transporting Sediment: 2576.40 cfs Width in Contracted Section: 83.15 ft Width Upstream that is Transporting Sediment: 82.45 ft Depth Prior to Scour in Contracted Section: 8.48 ft Unit Weight of Water: 62.40 lb/ft^3 Unit Weight of Sediment: 165.00 lb/ft^3 Results of Live Bed Method Shear Velocity: 0.52 ft/s Fall Velocity: 0.09 ft/s Average Depth in Contracted Section after Scour: 8.23 ft Scour Depth for Live Bed: -0.24 ft

Input Parameters Average Depth Upstream of Contraction: 2.98 ft D50: 0.000000 ft Average Velocity Upstream: 1.68 ft/s Results of Scour Condition Critical velocity above which bed material of size D and smaller will be transported: 0.00 ft/s Contraction Scour Condition: Live-Bed Live Bed and/or Clear Water Input Parameters Temperature of Water: 60.00 ºF Slope of Energy Grade Line at Approach Section: 0.0010 ft/ft Flow in Contracted Section: 240.74 cfs Flow Upstream that is Transporting Sediment: 164.89 cfs Width in Contracted Section: 21.63 ft Width Upstream that is Transporting Sediment: 32.91 ft Depth Prior to Scour in Contracted Section: 4.60 ft

Input Parameters Average Depth Upstream of Contraction: 5.50 ft D50: 0.000000 ft Average Velocity Upstream: 1.38 ft/s Results of Scour Condition Critical velocity above which bed material of size D and smaller will be transported: 0.00 ft/s Contraction Scour Condition: Live-Bed Live Bed and/or Clear Water Input Parameters Temperature of Water: 60.00 ºF Slope of Energy Grade Line at Approach Section: 0.0010 ft/ft Flow in Contracted Section: 163.48 cfs Flow Upstream that is Transporting Sediment: 194.16 cfs Width in Contracted Section: 39.44 ft Width Upstream that is Transporting Sediment: 25.60 ft Depth Prior to Scour in Contracted Section: 4.41 ft

Angle of Embankment to Flow: 92.29 Degrees Centerline Length of Embankment: 0.00 ft Projected Length of Embankment: 0.00 ft Width of Flood Plain: 0.00 ft Unit Discharge, Upstream in Main Channel (q1): 31.25 cfs/ft Unit Discharge in the Constricted Area (q2): 29.53 cfs/ft D50: 0.000700 ft Upstream Flow Depth: 8.62 ft Flow Depth Prior to Scour: 9.70 ft Result Parameters q2/q1: 0.95 Average Velocity Upstream: 3.62 ft/s Critical Velocity above which Bed Material of Size D and Smaller will be Transported: 1.42 ft/s Scour Condition: Live Bed Embankment Length/Floodplain Width Ratio: 0.00 Scour Condition: a (Main Channel) Amplification Factor: 1.20 Flow Depth including Contraction Scour: 8.22 ft Maximum Flow Depth including Abutment Scour: 9.86 ft Scour Hole Depth from NCHRP Method: 0.16 ft

Angle of Embankment to Flow: 87.71 Degrees Centerline Length of Embankment: 0.00 ft Projected Length of Embankment: 0.00 ft Width of Flood Plain: 0.00 ft Unit Discharge, Upstream in Main Channel (q1): 31.25 cfs/ft Unit Discharge in the Constricted Area (q2): 29.53 cfs/ft D50: 0.000700 ft Upstream Flow Depth: 8.62 ft Flow Depth Prior to Scour: 9.70 ft Result Parameters q2/q1: 0.95 Average Velocity Upstream: 3.62 ft/s Critical Velocity above which Bed Material of Size D and Smaller will be Transported: 1.42 ft/s Scour Condition: Live Bed Embankment Length/Floodplain Width Ratio: 0.00 Scour Condition: a (Main Channel) Amplification Factor: 1.20 Flow Depth including Contraction Scour: 8.22 ft Maximum Flow Depth including Abutment Scour: 9.86 ft Scour Hole Depth from NCHRP Method: 0.16 ft

Bridge Scour Analysis: 100-Year Bridge Scour Analysis

Main Channel Contraction Scour Contraction & Long Term Scour is applied method due to greater scour.

Contraction & Long Term Scour is applied method due to greater scour.

Applied Contraction Scour Depth 0.06 ft Pressure Scour does NOT apply Pressure Scour Depth 0.06 ft Live Bed Contraction Scour Depth 0.06 ft

Local Scour at Abutments Left Abutment Abutment Scour Method: NCHRP Method Abutment Scour Depth 0.57 ft Total Scour at Abutment 0.57 ft Total Scour Elevation at Abutment Right Abutment Abutment Scour Method: NCHRP Method Abutment Scour Depth 0.57 ft Total Scour at Abutment 0.57 ft

Input Parameters Average Depth Upstream of Contraction: 9.54 ft D50: 0.000700 ft Average Velocity Upstream: 3.90 ft/s Results of Scour Condition Critical velocity above which bed material of size D and smaller will be transported: 1.44 ft/s Contraction Scour Condition: Live-Bed Live Bed and/or Clear Water Input Parameters Temperature of Water: 60.00 ºF Slope of Energy Grade Line at Approach Section: 0.0032 ft/ft Flow in Contracted Section: 2886.59 cfs Flow Upstream that is Transporting Sediment: 3071.36 cfs Width in Contracted Section: 83.17 ft Width Upstream that is Transporting Sediment: 82.45 ft Depth Prior to Scour in Contracted Section: 8.94 ft…