DEWA_10(6)218(2) Dingman Bridge H and H Report_Final.pdf

1 H-H Report NP DEWA 10(6)218(2)

Hydrologic & Hydraulic Analysis and Report

FHWA/NPS Project No: DEWA 10(6) 218 (2)

Structure Number, 4320-019P Dingmans Falls Access Bridge #1 over Dingmans Creek

HYDROLOGIC AND HYDRAULIC REPORT

Delaware Township Pike County, Pennsylvania

Owner: Delaware Water Gap National

Recreational Area, National Park Service

Applicant: Federal Highway Administration Eastern Federal Lands Highway Division 22001 Loudon County Parkway, Bldg. E2--3-529 Ashburn, VA 20147

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ENGINEER’S CERTIFICATION

The Federal Government is exempt of providing professional seals. An engineer employed by the Unites States is exempt from license requirements of Title 63, Chapter 5, Pennsylvania Statutes, which include signing and sealing the documents.

“FHWA/EFL hereby certify to the best of our knowledge, information and belief, that the information contained in the accompanying plans, specifications and reports has been prepared in accordance with accepted engineering practice, is true and correct, and is into the fullest extent possible, except where it conflicts with Chapter 7 of the FHWA/EFL Project Development and Design Manual (PDDM)

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Table of Contents

Introduction and project description

Site Data

Existing Structure

Proposed Structure

Flooding

Environmental Considerations

Fish Passage

Stream Characteristics

Hydrologic Analysis

ACT 167

Design Events

Hydraulic Analysis

FEMA Considerations

Topographic Data

SMS Model

Existing Bridge Data

Proposed Bridge Data

SMS Model Results

Validation

Temporary Conditions

Scour Analysis

Risk Assessment

Conclusion

Summary Data

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List of Figures

Figure 1 – Project Location Figure 2 – Angle Representation Region (ARR) Plot Figure 3A – Q2 Temporary WSELs and depth for the construction of Abutment#1 Figure 3B – Q2 Temporary Stream Profile in front of stream diversion for Abutment#1 Figure 3C – Q2 Temporary XS at the upstream end of stream diversion for Abutment#1 Figure 4A – Q2 Temporary WSELs and depth for the construction of Abutment#2 Figure 4B – Q2 Temporary Stream Profile in front of stream diversion for Abutment#2 Figure 4C – Q2 Temporary XS at the upstream end of stream diversion for Abutment#2 Figure 5 – Bridge Scour Summary Table for Q100, Q200 & Q500 Figure 6 – Q500 Scour Plot Figure 7 –Velocities at the Proposed Bridge Centerline

List of Tables

Table 1 – Estimated Peak Flows and WSELs Table 2 – Existing vs. Proposed WSELs and Velocities Table 3 – Temporary WSELs Summary Table 4 – Average Velocities at Bridge Centerline

List of Appendices

Appendix A – USGS Topo Map Appendix B – Bridge Inspection Report (BIP) Appendix C – Pre-Development Photos (Existing structure, upstream and downstream channel) Appendix D - Drawings of the proposed structure and roadway approaches (R Sheets) Appendix E – Trout Map Print Screen Appendix F – USGS Web Soil Map Appendix G – USGS StreamStats Report Appendix H – SHR-2D Cross Sections for WSELs at the entrance of the proposed bridge Appendix I – SHR-2D Stream Profile WSELs Appendix J – SHR-2D Floodplain delineation comparison FEMA vs existing vs proposed.

Appendix K – SHR-2D Upstream and Downstream Cross Section Plots Appendix L – Detailed construction sequence information is available in the E&S plans (M Sheets) Appendix M – Riprap Analysis Report

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INTRODUCTION AND PROJECT DESCRIPTION

This report describes the analysis and results of a hydrologic and hydraulic study that was performed on the Dingmans Falls Access Bridge #1 (Structural Number 4320-019P) over Dingmans Creek. The bridge is within Delaware Water Gap National Recreation Area which is managed by the National Park Service. The proposed project involves replacing a prestressed concrete box beam (CIP Deck) that carries the Dingmans Fall Access Road (NPS Route 218) over Dingmans Creek. The site is located in Delaware Township, Pike County, Pennsylvania. Its location on the USGS quadrangle map entitled Lake Maskenozha, PA is approximately 41° 13' 29.20" N latitude and 74° 52' 48.10" W longitude. The project location is shown in Figure 1 and USGS Topo Map in Appendix A.

FIGURE 1: PROJECT LOCATION

The project is necessary because the existing bridge is in fair to poor condition overall. The proposed project involves replacing the existing structure with the same horizontal alignment and slightly vertical raise, requiring minimal approach roadway work. There will be no reduction in the existing waterway opening.

SITE DATA

A topographic survey was conducted by the FHWA/EFL Survey team. All elevations in this report are referenced to the NAVD 1988 datum unless otherwise noted. FHWA/EFL conducted a scoping field review on November 15, 2016, and a plan-in-hand field review on October 8, 2020, to collect

6 H-H Report NP DEWA 10(6)218(2) information for the H&H study. Normal flow estimates were based on observed water depths during the site visit and the surveyed edge-of-stream elevations.

EXISTING STRUCTURE

The existing structure is a single-span prestressed concrete box beam bridge with a cast-in-place (CIP) deck. The bridge is 59 feet long with a clear span width of 46 feet, an out-to-out length of 23.1 feet, and a 26-degree skew relative to the flow direction. The abutments are aligned with the stream flow and have no piers.

The bridge as-built drawings show the low chord at 464.45 feet, but field mapping indicates this is incorrect. Using a combination of field mapping and the Bridge Inspection (BIP) Report, the low chord of the existing bridge was estimated. The BIP Report suggests the low steel elevation (LSEL) is 3 feet below the top of the bridge, and based on the field mapping, the top of the deck is at approximately 448.72 feet. This places the minimum low chord elevation at approximately 445.92 feet.

The bridge has timber rails on both sides measuring about 2.5 feet above the deck. The bridge deck and both approach roadways are superelevated. The minimum hydraulic opening is approximately

525.08 square feet. Based on field observations and mapping data, the water level in the stream averaged 1 foot and varied up to 2 feet. Therefore, with the estimated low chord elevation at 445.92 feet, a thalweg elevation of 435.75 feet, and a maximum observed depth of 2 feet, the minimum underclearance is approximately 8.17 feet (from the low chord elevation and water surface).

The BIP Report indicates the structure is exhibiting advanced deterioration of the transverse tensioning system, rotation of the southernmost beam, significant gaps between box beams, widespread cracking on the undersides of the box beams with exposed and rusted rebar and prestressing strands. The report also notes minor to moderate deterioration of the concrete abutments and wingwalls, including cracking with efflorescence and staining, and several areas of delamination. The BIP report is in Appendix B, and pre-development photos are in Appendix C.

Approximately 5800 feet downstream of the bridge is the confluence with the Delaware River.

About 1000 feet upstream is the Dingmans Falls Access Bridge #2 (SN 4320-005P), a single-span bridge carrying Dingmans Falls Access Road (NPS Route 218) over Dingmans Creek. Both Hydraulic Controls are outside of the limits of the hydraulic model and does not affect the hydraulics at the site according to FHWA Publication No. FHWA-HIF-19-061, 2D Hydraulic Modeling for Highways in the River Environment. The confluence with the Delaware River and upstream bridge are far enough from the area of interest to allow for natural flow distribution.

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PROPOSED STRUCTURE

The proposed structure is a single-span prestressed concrete adjacent box beam bridge (AASHTO BI-48) with a LSEL of 446.37 feet on the same horizontal roadway alignment. The bridge will be 65 feet long with a clear span width of 59 feet, an out-to-out length of 28.13 feet, and a 39-degree skew relative to the flow direction. The proposed structure will include a slight realignment of Abutment #1 to better fit the channel, a 6-foot setback for Abutment #2 to move it away from the creek, and a slightly raised roadway profile with minimal approach work.

The project limits extend approximately 89 feet on the west approach and 46 feet on the east approach for tie-ins and construction activities. The proposed bridge will have rails on both sides measuring about 2.16 feet above the deck. The bridge deck and both approach roadways will be superelevated. The minimum underclearance, from the low chord elevation to the normal water surface elevation, is approximately 8.62 feet. The minimum hydraulic opening, the lesser of the upstream and downstream openings, is approximately 552.83 square feet. Grading will extend from the existing edge of water to the proposed abutments. Drawings of the proposed structure and roadway approaches (R Sheets) are in Appendix D.

FLOODING

High water marks from historical flood events were not observed on or around the existing bridge during site visit. The project is located in a National Park, due to the remote location of the project site, local testimony was not obtained during the site investigation.

ENVIRONMENTAL CONSIDERATIONS

Dingmans Creek is a perennial stream and upstream tributary of the Delaware River Basin. The Pennsylvania Water Quality Standards, Drainage list C, classify Dingmans Creek as a High-Quality, Cold-Water Fishery (HQ-CWF, MF). Dingmans Creek is an upstream tributary of the Middle Delaware River, which is classified as WWF, MF under Chapter 93.

25 Pa. Code Chapter 93. Water Quality Standards (pacodeandbulletin.gov)

The Pennsylvania Fish and Boat Commission (PFBC) lists Dingmans Creek as natural reproduction trout waters but does not list it as a Class A or stocked trout stream. Therefore, in-stream restrictions such as time restrictions for construction activities for a stocked trout stream are not applicable. Trout Map print screen is in Appendix E.

Trout Water Classifications (fishandboat.com) trout_repro.pdf (fishandboat.com) https://www.pacodeandbulletin.gov/Display/pacode?file=/secure/pacode/data/025/Chapter93/chap93toc.html https://www.fishandboat.com/Fishing/All-About-Fish/Catch-PA-Fish/Trout/Pages/TroutWaterClassifications.aspx https://www.fishandboat.com/Fishing/All-About-Fish/Catch-PA-Fish/Trout/Documents/trout_repro.pdf

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FISH PASSAGE

The local fish habitat will be temporarily affected by construction of the proposed bridge. The proposed bridge is longer than the existing bridge resulting is less constriction of the channel;

therefore, the fish habitat will function as normal when the proposed bridge is in place.

STREAM CHARACTERISTICS

The site is within a forested landscape. The past and present uses of the area are for conservation and recreation. The upstream and downstream overbanks are steep sloped with vegetation, shrubs, and trees along the channel banks.

USGS Web Soil Survey indicates the type of soil is in Hydrologic group A which are soils with high infiltration rates and a soil classification of very stony soils with a combination of very gravelly loam (CL-ML) and very cobbly sandy loam (GC). The USGS Web Soil Map is in Appendix F.

The natural channel has a profile gradient of 0.005, manning n of 0.04, and flows in an easterly direction. The stream has a well-defined channel upstream and downstream of the bridge. The bottom and top channel widths vary through the study area but varies from 33 and 50 feet. The channel has a depth of approximately 40 feet from bed to top of bank and side slopes that vary from 1V:0.5H to 1V:2H in the vicinity of the bridge. During the field mapping, our survey team observed that the water level in the stream averaged one foot and varied up to maximum depth of 2 feet.

Due to the location of the low chord relative to flood elevations, no potential for ice jams at the bridge exists. Water stages at the project site are not affected by reservoirs or flood control projects.

HYDROLOGIC ANALYSIS

The Dingmans Falls Creek is within the FEMA mapped floodplains Zone A, which indicates that there are no base flood elevations determined by a detailed study at this location.

We considered using two USGS stream gages (01438500 and 0144000) located several miles from our structure to develop a flood-frequency curve. However, the drainage area of these gages differs by more than 25% from our structure’s drainage area, making them unsuitable according to the HDS2, Highway Hydrology Third Edition, Chapter 5.4 area-ratio method.

Instead, hydrology analysis was performed using the USGS StreamStats® online tool for hydrologic analysis. This tool automatically delineates drainage areas and computes peak flow discharges using regional regression equations. Since USGS StreamStats is approved by the FHWA/EFL, no

9 H-H Report NP DEWA 10(6)218(2) further hydrology adjustments are needed for this project. The analysis showed that the drainage area is 15.89 square miles, with 81% forest, 16.7% urban, and 10% ponds and lakes. The watershed does not contain any carbonate rock. The USGS StreamStats data is in Appendix G and FEMA Firmette in Appendix J.

ACT 167

The Proposed Project occurs entirely on federal-owned property and is funded through federal transportation funding sources. In addition, Pike County does not have an approved Act 167 Plan for Dingmans Creek watershed.

https://files.dep.state.pa.us/Water/BPNPSM/StormwaterManagement/Act%20167/Act167List_2.15.2024.xlsx https://www.dep.pa.gov/Business/Water/CleanWater/StormwaterMgmt/Pages/Act-167.aspx

DESIGN EVENTS

The design standard is to provide 2 feet of freeboard for the 50-year return period per the PDDM, Section 7.4.3.4. Please refer to Table 1 for a summary of the flow rates along with their corresponding WSEL, and freeboards. Based on our analysis, the proposed structure meets the design standards per the PDDM. SRH-2D Cross Sections with WSELs are the entrance of the proposed bridge are in Appendix H.

Table 1: Estimated Peak Flows and WSELs

Existing Proposed

(LSEL = 445.92’) (LSEL = 446.37’)

Event Flow WSEL Freeboard WSEL Freeboard (cfs) (feet) (feet) (feet) (feet)

2-year 540 439.09 6.83 438.94 7.43 25-year 1898 441.89 4.03 441.43 4.94 50-year 2150 442.32 3.60 441.86 4.51

100-year 2610 443.11 2.81 442.65 3.72 200-year 3150 443.98 1.94 443.45 2.92 500-year 3910 445.17 0.75 444.24 2.13

Note: WSELs were taken at the entrance of the proposed bridge

HYDRAULIC ANALYSIS

The hydraulic analysis was performed using the Sedimentation and River Hydraulics model (SRH- 2D) within the Surface-water Modeling System (SMS Version 13.02.14). SRH-2D is the preferred river modeling approach by FHWA/EFL for river crossing structures.

https://files.dep.state.pa.us/Water/BPNPSM/StormwaterManagement/Act%20167/Act167List_2.15.2024.xlsx https://www.dep.pa.gov/Business/Water/CleanWater/StormwaterMgmt/Pages/Act-167.aspx

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The design objective of the 2-D hydraulic modeling for this project was to obtain the water surface elevations (WSELs), flow depth and velocities for analysis of scour potential at the proposed bridge crossing. Existing, proposed, and temporary conditions were modeled based on field survey data, proposed site modifications, and peak discharge calculations. As requested by DEP, the SRH-2D model and HYD toolbox files will also be provided with this memo.

FEMA CONSIDERATIONS

The Dingmans Falls Creek is within the FEMA mapped floodplains Zone A, which indicates that there are no base flood elevations determined by a detailed study at this location. Based on our analysis, the proposed structure will not increase the 100-year water surface elevations, it will reduce it by 0.46 feet, as shown in Table 1. SRH-2D Stream Profile Plot is in Appendix I. Floodplain delineation comparison is in Appendix J.

TOPOGRAPHIC DATA

Field topographic was collected by FHWA/EFL survey team. This survey data extended approximately 575 feet upstream and 800 feet downstream of the bridge, and 175 feet beyond the channel top of slope. The vertical datum for all sources is NAVD 88, the horizontal datum for all sources is NAD 83. Projection was set to State Plane Coordinate System, Zone: Pennsylvania North (FIPS 3701).

SMS MODEL

The modeling mesh is a collection of vertices, edges, and faces defining the three-dimensional spatial information of the ground surface. SRH-2D uses a finite element mesh to define the geometric surface and set the modeling limits. The SRH-2D modeling site extends from approximately 575 feet upstream of the crossing to approximately 800 feet downstream. The model domain width was sized to extend a conservative distance to capture the anticipated flood boundaries.

Both the patch and paving mesh type were utilized to create the model mesh. Triangular paving was primarily used in the overbank regions while rectangular patching was used throughout the channel and the crossing. The mesh contains roughly 8,000 elements.

The mesh extents and total number of elements was developed to best capture geometric features impacting conveyance while also minimizing model inefficiencies and increased computational time. Upstream and downstream model extents were set to be far enough upstream and downstream to fully depict any impacts caused by the project based on our FHWA Publication Number: HIF-19-061.

Roughness coefficients, or Manning’s ‘n’ values, for the stream channel and overbank areas were determined based on field observation, aerial photographs, and Manning's n Values presented by Chow (1959). Generally, a value of 0.040 was used for the channel, and 0.08 for the vegetated overbank areas.

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All simulations were run in a steady state. Peak discharges, determined using StreamStats, were used as Inlet Q boundary conditions. And the SMS “Channel Calculator” tool was used to compute and assign a normal depth for the outflow boundary condition using a rating curve.

All project SRH-2D model controls were set to a 1-second timestep. All simulations were set to a dry initial condition, and the total period of time that the simulation run analyzed was set to 3-hours.

This was a long enough period of time to allow the model to reach a steady state solution for all simulation runs. Output frequency was set to 15-minute intervals. The default parabolic turbulence parameter option was selected and set to the default value of 0.7.

EXISTING BRIDGE DATA

Existing bridge geometry, abutment and wingwall locations and their respective elevations were obtained directly from the field survey map.

PROPOSED BRIDGE DATA

Proposed bridge geometry, abutment and wingwall locations and their respective elevations are based on the proposed EFL Bridge team TS&L and in accordance with the Site Data section of this memo. The terrain file used in the proposed conditions SMS simulations was modified to incorporate proposed grading and riprap layout through the bridge crossing. Drawings of the proposed structure (R Sheets) is in Appendix D. Proposed Contours (M Sheets) are in Appendix L.

SMS MODEL RESULTS

Since there are no FEMA Cross Sections or BFEs available for FEMA Zone A, we created two observation cross sections within our model to evaluate changes in existing and proposed conditions along our channel for several design events. One cross section is upstream of the structure, and one is downstream. Refer to Table 2 for details. SHR-2D Upstream and Downstream Cross Section plots are in the Appendix K. As requested by PA DEP, the SRH-2D model will also be provided with this memo.

Table 2: Existing vs. Proposed WSELs and Velocities Flood Event Location

Water Surface Elevation (ft) Diff.

Velocity (fps) Diff.

Existing Proposed Existing Proposed

Q2 Upstream (+/- 400ft) 451.07 450.97 -0.10 4.84 4.78 -0.06

Downstream (+/-400ft) 437.16 437.02 -0.15 5.21 5.44 -0.02

Q25 Upstream (+/- 400ft) 454.43 454.41 -0.02 7.30 7.14 -0.16

Downstream (+/-400ft) 439.58 439.47 -0.11 8.41 8.01 -0.40

Q50 Upstream (+/- 400ft) 454.91 454.41 -0.50 7.62 7.44 -0.18

Downstream (+/-400ft) 439.96 439.79 -0.17 8.63 8.40 -0.23

Q100 Upstream (+/- 400ft) 455.73 455.71 -0.01 8.07 7.88 -0.19

Downstream (+/-400ft) 440.52 440.32 -0.20 9.17 9.07 -0.09

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Q200 Upstream (+/- 400ft) 456.30 456.30 0.00 8.62 8.08 -0.54

Downstream (+/-400ft) 441.08 440.86 -0.22 9.86 9.80 -0.06

Q500 Upstream (+/- 400ft) 457.60 457.60 0.00 9.20 9.02 -0.18

Downstream (+/-400ft) 441.72 441.51 -0.21 10.79 10.61 -0.18

25-year storm

Water surface elevations are reduced by an average of 0.16 feet upstream and 0.40 feet downstream of the structure with no backwater increases. Stream velocities are also reduced in the reach upstream and downstream of the proposed bridge. The proposed low chord does not contact the 25-year water surface, and neither roadway approach is overtopped.

50-year storm

Water surface elevations are reduced by an average of 0.50 feet upstream and 0.17 feet downstream, with no backwater increases. Stream velocities are also reduced in the reach upstream and downstream of the proposed bridge. The proposed structure will meet the FHWA/EFL PDDM design standard of 2 feet of freeboard over the 50-year return period, and no roadway overtopping occurs.

100-year storm

Water surface elevations are reduced by an average of 0.01 feet upstream and 0.20 feet downstream, with no backwater increases. Stream velocities are also reduced in the reach upstream and downstream of the proposed bridge. The existing bridge has 2.81 feet of freeboard, while the proposed structure will provide 3.72 feet of freeboard over the 100-year return period.

The proposed low chord will not be impacted by the 100-year water surface, and neither roadway approach will be overtopped.

VALIDATION

Our SRH-2D models simulations ran successfully, and no errors were reported.

Typically, an SRH-2D model calibration and validation process starts with the collection of observed data from a historical event near the project area. Then, upon completion of the model simulation, we compare the computed WSEs and observed values. If the computed WSE results match the observed data, then the model is considered to be calibrated and validated.

However, high water marks from historical flood events were not observed on or around the existing bridge during site visit and given the remote location of the project site. For projects without historical flood data, we typically perform a sensitivity testing on the SRH-2D models to determine confidence in the results. Various model parameters were adjusted to understand the model's sensitivity, and the results were found adequate.

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Additionally, we evaluated the overall SRH-2D model mesh quality using an Angle Representation Region (ARR) plot. This ensures a balance between detailed ground representation, appropriate hydraulic resolution, and model run times. The mesh elements for this project fall within the good quality threshold according to the ARR plot.

FIGURE 2: ANGLE REPRESENTATION REGION (ARR) PLOT

TEMPORARY CONDITIONS

An erosion and sedimentation control (E&S) plan has been developed to limit impacts on the perennial stream during the construction of the new bridge. The construction will be done in several phases/stages. This memo focuses on the two temporary stream diversions needed for the abutment construction and their effects on water surface elevations. Detailed construction sequence information is available in the E&S plans (M Sheets) in Appendix L.

The first temporary stream diversion will be along the north side of the channel for Abutment #1, and the second will be along the south side for the construction of Abutment #2. These diversions will not be installed simultaneously; only one diversion will be in place at a time during different construction phases/stages.

We ran an SRH-2D model simulation for the two phases/stages to calculate the increase in water surface elevation caused by each temporary stream diversion. The mesh elements created for these models matches the width and location of the proposed diversion width. These elements were assigned a "none" mesh element type. This setting creates a vertical wall along those elements and assume them as dry. This method helps us estimate the resulting water surface elevation increase.

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FIGURE 3A: Q2 TEMPORARY WSELS AND DEPTHS FOR THE CONSTRUCTION OF ABUTMENT #1

FIGURE 3B: Q2 STREAM PROFILE IN FRONT OF THE STREAM DIVERSION FOR ABUTMENT #1

FIGURE 3C: Q2 TEMPORARY XS AT UPSTREAM END FOR THE CONSTRUCTION OF ABUTMENT #1

See Figure 3B for WSELs along this blue line See Figure 3C for WSELs along this green line

Potential Bypass

Flow

Potential Bypass

Flow

Increase in WSELS due potential bypass flow.

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FIGURE 4A: Q2 TEMPORARY WSELS AND DEPTH FOR THE CONSTRUCTION OF ABUTMENT #2

FIGURE 4B: Q2 STREAM PROFILE IN FRONT OF THE STREAM DIVERSION FOR ABUTMENT #2

FIGURE 4C: Q2 TEMPORARY XS AT UPSTREAM END FOR THE CONSTRUCTION OF ABUTMENT #2

See Figure 4B for WSELs along this blue line

See Figure 4C for WSELs along this green line

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Table 3: Temporary WSELs Summary

Event Flow Existing

WSEL

Highest Temporary

WSEL for the construction of

Abutment 1

Highest Temporary

WSEL for the construction of

Abutment 2

Proposed WSELs

(cfs) (feet) (feet) (feet) (feet)

2-year 540 439.09 440* 439.55 438.94 Increase in WSELs 0.91 0.46

Min Freeboard by

0.50 0.50 EFL Detail E158-07

Min elevation for top of temporary stream diversion

440.50 440.05

*Figure 3C shows the water surface elevation at the upstream end for abutment 1 is 439.77 feet.

However, the SMS model indicates that some flow will bypass and slightly raise the water surface elevation where the stream diversion meets the banks. To ensure a dry working zone, we will use 440 feet as the water surface elevation to determine the minimum elevation for the top of the temporary diversion for abutment 1.

The 2-year flood event (540 cfs) was used to evaluate potential flood impacts during construction.

Our results show the maximum backwater increase of 0.91 feet from the existing conditions for a 2-year event. As a result, and to provide the 6-inch freeboard required by the EFL Detail E158-07, the temporary diversion for Abutment 1 should be placed at a minimum elevation of 440.50 feet, and the diversion for Abutment 2 at a minimum elevation of 400.05 feet.

Although some site disturbance will occur, the effects on the existing environment will not be significant. Due to the nature of bridge projects, construction activities close to the stream are unavoidable. However, proper implementation of soil erosion control measures, as detailed in the E&S plan (Appendix L) will minimize the impact on the stream.

SCOUR ANALYSIS

The scour design for Dingmans Falls Access Bridge #1 was performed for a 100-year storm event.

Since the bridge does not overtop, we evaluated scour for the worst-case scenario between a 200-year and 500-year storm event, as per Chapter 7 of the PDDM and the TechBrief: Hydraulic Considerations for Shallow Abutment Foundations (dated 12/21/18).

Scour analysis was performed using the Hydraulic toolbox software and SRH-2d models. The Hydraulic Toolbox imports geometry from the SRH-2D hydraulic model and uses the Bridge Scour Calculator to predict scour. The Bridge Scour Calculator is based on the latest FHWA HEC-18 and

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HEC-20 guidelines. Riprap design was performed using the Hydraulic Toolbox Riprap Calculator tool which is based on the latest FHWA HEC-23, V2 guideline.

The D50 of 0.0164 feet. (5 mm) was obtained from boring logs samples at the structure, and subsequent particle size analysis performed for this location. Since there is no additional information available for long term degradation, 1 foot of channel degradation was assumed. The boring logs samples also indicated that in the north abutment will be bearing on rock, and the south abutment will be bearing on competent native soil. Based on the TechBrief, Subsection 2.3(F), if the new shallow foundation cannot be keyed into competent rock, the top of the spread footing should be set below the worst-case total scour depth to avoid the need for scour countermeasures. Please refer to Figure 5 for the summary of scour depths and elevations to be used in the design of the foundations of the structure.

FIGURE 5: BRIDGE SCOUR SUMMARY FOR Q100, Q200 & Q500

FIGURE 6: Q500 SCOUR PLOT

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Table 4: Avg Velocities at Bridge CL

Event Avg Vel (fps)

100-year 8.95

200-year 9.44

500-year 10.05

FIGURE 7: VELOCITIES AT THE PRO BRIDGE CL

The analysis results indicated that the worst-case total scour elevation of 433.66 feet occurs during a 500-year storm. The channel thalweg at the bridge outlet is 435.75 feet. Bridge drawings show that the top of the spread footing for both abutments will be set at an elevation of 433 feet, which is below the maximum anticipated scour depth. Therefore, scour is not a concern, and no scour countermeasures are required. However, future erosion is a potential concern at Abutment #2. To mitigate this, we recommend placing Class 3 riprap with a depth of 24 inches at a minimum slope of 1.5H:1V. Riprap layout and plan view(R-Sheets) are in Appendix D. Riprap Analysis Report is in Appendix M.

RISK ASSESSMENT

Based on our analysis results, the proposed project will not increase the risk of flooding upstream or downstream of the proposed bridge. The project results in no increases to the water surface elevation for 25-, 50-, 100-, 200- and 500-year flood events. The overtopping event for the existing and proposed bridge is larger than the 500-year flood; therefore, the upper limit of serviceability at the project site will remain the same from the existing condition.

Temporary conditions will result in a maximum backwater increase of 0.91 feet for the 2-year event. The temporary 2-year flood boundary will be confined to the main channel in existing and temporary conditions and will not affect any structures in the floodplain. The temporary 2-year water surface elevation increases will not increase risk to adjacent properties; therefore, flowage easements will not be obtained.

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CONCLUSION

A hydrologic and hydraulic study was performed on the Dingmans Falls Access Bridge #1 (SN 4320- 019P) over Dingmans Creek. The proposed project will replace the existing single-span Prestressed Concrete Box Beam (CIP Deck structure) with a single-span P/S Adjacent Box Beam (AASHTO BI-

48) structure following the same horizontal alignment and a slightly vertical raise, requiring minimal approach roadway work.

The proposed structure will meet the FHWA/EFL PDDM design standard of 2 feet of freeboard over the 50-year return period. The existing and proposed bridges will not overtop for the 500-year event and will have significant freeboard. The proposed project will not increase water surface elevations upstream or downstream of the bridge for the 25-, 50-, 100-, 200- and 500-year flood events. The structure has been designed to provide a stream crossing that safely conveys flood flows without increasing the risk of flooding to surrounding areas. Scour is not a concern because the top of the spread footing is set below the worst-case total scour depth. However, riprap is recommended at Abutment #2 to mitigate potential future erosion.

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SUMMARY DATA

Location Data

MPSMS# - Municipality Delaware Township

County Pike State Route- Section

Dingmans Fall Access Road (NPS Route 218)

Location - USGS Quadrangle Lake Maskenozha Station -

Latitude 41° 13' 29.20" N Segment/Offset -

Longitude 74° 52' 48.10" W Functional Classification

NPS Class 3 - Special Purpose Public Park Road (Recreational). Roads serves low speed traffic areas.

Channel Data Stream Name Dingmans Creek Normal Stream Flow depth 1' to 2' Drainage Area 15.89 square miles Temp Wetland Impacts 0 ac Hydrology Method Used StreamStats Permanent Wetland Impacts 0 ac FEMA Flood Zone A Temporary fill below OHW 220 cy River Basin (USACE) Delaware River Permanent fill below OHW 0 cy

Bridge Characteristics

Existing Structure Proposed Structure

Bridge Type Prestressed Concrete Box Beam; CIP Deck

P/S Adjacent Box Beam;

AASHTO BI-48

Number of Spans 1 1 Skew (relative to flow direction) 26° 39°

Normal Clear Span (Width) 46.06' 59'

Out-to-out Length (Dir of Flow) 23.1' 28.13'

Total Length of Channel Impacted North Side- 33' South Side - 62'

North Side - 40' South Side - 62.5'

Low Chord Elevation 464.45' * 446.37' Minimum Underclearance 11.4' 9.37' Open Area (sqft) 525.084 552.83 Note: There is a potential discrepancy with the low cord elevation. Asbuilt shows 464.45', but bridge is not lowered 20ft. The estimated LSEL is 445.92'.

21 H-H Report NP DEWA 10(6)218(2)

Hydraulic Data Existing Structure Proposed Structure

Hydraulic Method Used SRH-2D (SMS) SRH-2D (SMS)

Return Period Designation Q (cfs)

WSE

(feet)

Velocity (fps)

Q (cfs)

WSE

(feet)

Velocity (fps)

2-year FHWA/PDDM 540 439.09 4.66 540 438.94 3.77 25-year FHWA/PDDM 1898 441.89 8.53 1898 441.43 6.93 50-year FHWA/PDDM 2150 442.32 9.10 2150 441.86 7.34

100-year FHWA/PDDM 2610 443.11 10.01 2610 442.65 8.06 200-year FHWA/PDDM 3150 443.98 10.92 3150 443.45 8.78 500-year FHWA/PDDM 3910 445.17 12.01 3910 444.24 9.70

Overtopping Event > 500-year > 500-year

Note: WSELs were taken at the entrance of the proposed bridge

22 H-H Report NP DEWA 10(6)218(2)

APPENDICES

isis.rosado-vazquez Typewritten Text

APPENDIX A

USGS Map and Photographs

Callout Project Location

-74.880028, 41.224778 isis.rosado-vazquez Text Box Appendix A- USGS Map isis.rosado-vazquez Text Box Lake Maskenozha, PA

Appendix B

Bridge Inspection Report

APPENDIX C

Photographs

Appendix A – PHOTOGRAPHS

Figure 1: Dingmans Road looking south

Figure 2: Dingmans Road looking north

Figure 3: Bridge over Dingmans Falls Creek looking Downstream.

Figure 4: Dingmans Falls Creek looking Upstream.

Figure 5: Downstream view of Dingmans Falls Creek

Figure 6: Dingmans SW corner looking Upstream

APPENDIX D

Drawings of the proposed structure and roadway approaches (R Sheets)

APPENDIX E

Trout Map Print Screen

APPENDIX F

USGS Websoil Map

Soil Map—Pike County, Pennsylvania (DEWA 10(6)218(2) Dingman Bridge)

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

6/7/2024

508900 509000 509100 509200 509300 509400 509500 509600 509700 509800 509900 510000 510100 510200 510300 510400 510500

508900 509000 509100 509200 509300 509400 509500 509600 509700 509800 509900 510000 510100 510200 510300 510400 510500

41° 13' 50'' N

3'

9' ' W

41° 13' 50'' N

2'

8' ' W

41° 13' 16'' N

3'

9' ' W

41° 13' 16'' N

2'

8' ' W

N

Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 18N WGS84 0 350 700 1400 2100

Feet 0 100 200 400 600

Meters Map Scale: 1:7,490 if printed on A landscape (11" x 8.5") sheet.

Soil Map may not be valid at this scale.

MAP LEGEND MAP INFORMATION

Area of Interest (AOI) Area of Interest (AOI)

Soils Soil Map Unit Polygons

Soil Map Unit Lines

Soil Map Unit Points

Special Point Features Blowout

Borrow Pit

Clay Spot

Closed Depression

Gravel Pit

Gravelly Spot

Landfill

Lava Flow

Marsh or swamp

Mine or Quarry

Miscellaneous Water

Perennial Water

Rock Outcrop

Saline Spot

Sandy Spot

Severely Eroded Spot

Sinkhole

Slide or Slip

Sodic Spot

Spoil Area

Stony Spot

Very Stony Spot

Wet Spot

Other

Special Line Features

Water Features Streams and Canals

Transportation Rails

Interstate Highways

US Routes

Major Roads

Local Roads

Background Aerial Photography

The soil surveys that comprise your AOI were mapped at 1:24,000.

Warning: Soil Map may not be valid at this scale.

Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale.

Please rely on the bar scale on each map sheet for map measurements.

Source of Map: Natural Resources Conservation Service Web Soil Survey URL:

Coordinate System: Web Mercator (EPSG:3857)

Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required.

This product is generated from the USDA-NRCS certified data as of the version date(s) listed below.

Soil Survey Area: Pike County, Pennsylvania Survey Area Data: Version 16, Sep 7, 2023

Soil map units are labeled (as space allows) for map scales 1:50,000 or larger.

Date(s) aerial images were photographed: May 31, 2022—Oct 27, 2022

The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident.

Soil Map—Pike County, Pennsylvania (DEWA 10(6)218(2) Dingman Bridge)

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

6/7/2024

Map Unit Legend

Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI

7C Shohola-Edgemere complex, 8 to 15 percent slopes, very rubbly

2.7 1.5%

9B Craigsville-Wyoming complex, 0 to 8 percent slopes, extremely stony

19.3 10.5%

21C Manlius very channery silt loam, 8 to 15 percent slopes, very bouldery

8.7 4.8%

60B Mardin channery silt loam, 0 to 8 percent slopes, stony

1.5 0.8%

61C Mardin stony loam, 8 to 15 percent slopes, extremely stony

8.2 4.5%

89B Chenango gravelly fine sandy loam, 0 to 8 percent slopes

1.3 0.7%

89C Chenango gravelly fine sandy loam, 8 to 15 percent slopes

5.8 3.2%

111B Edgemere-Shohola complex, 3 to 15 percent slopes, very rubbly

0.2 0.1%

121D Manlius-Arnot-Rock outcrop complex, 15 to 30 percent slopes

23.5 12.8%

121F Manlius-Arnot-Rock outcrop complex, 30 to 80 percent slopes

81.9 44.6%

442C Wyoming very cobbly sandy loam, 8 to 15 percent slopes

30.4 16.6%

Totals for Area of Interest 183.4 100.0%

Soil Map—Pike County, Pennsylvania DEWA 10(6)218(2) Dingman Bridge

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

Engineering Properties–Pike County, Pennsylvania

Map unit symbol and soil name

Pct. of map unit

Hydrolo gic group

Depth USDA texture Classification Pct Fragments Percentage passing sieve number— Liquid limit

Plasticit y index

Unified AASHTO >10 inches

3-10 inches

4 10 40 200

In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H

9B—Craigsville- Wyoming complex, 0 to 8 percent slopes, extremely stony

Craigsville 50 A 0-5 Very gravelly loam CL-ML, ML, SC, SM, SC-SM

A-2, A-4 2-15- 15 0-13- 25 65-78-

60-73-

40-58-

25-43-

20-25 -35

NP-5

-10

5-27 Gravelly sandy loam, cobbly loam, very gravelly sandy loam

GC, GM,

SC,

SM,

SC-SM

A-1, A-2, A-4

0- 0- 0 25-43-

50-65-

30-48-

25-43-

15-28-

15-22 -27

NP-5

-10

27-77 Very gravelly loamy sand, very gravelly sandy loam, extremely cobbly loamy sand

GC, GC-

GM,

GM

A-1, A-2 0- 0- 0 35-65-

35-45-

30-40-

20-33-

10-18-

15-20 -25

NP-4 -8

Wyoming 40 A 0-3 Very cobbly sandy loam

GM, GP-

GM,

SM,

SW-SM

A-1, A-2, A-3

0- 0- 0 10-35-

40-65-

30-55-

10-35-

8-22- 35 20-30 -35

NP-3 -5

3-33 Gravelly sandy loam, very gravelly sandy loam, very cobbly fine sandy loam

GM, GP-

GM,

SM,

SP-SM

A-1, A-2, A-3

0- 0- 0 0-13- 25 40-58-

35-53-

5-30- 55 5-20- 35 15-22 -27

NP-3 -5

33-72 Extremely cobbly loamy coarse sand, very gravelly sand, gravelly sandy loam

SM, SW,

GP-GM,

GW

A-1 0- 3- 5 5-18- 30 30-48-

20-38-

5-28- 50 1- 7- 13 10-18 -25

NP-3 -5

Engineering Properties---Pike County, Pennsylvania DEWA 10(6)218(2) Dingman Bridge Soil REport

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

APPENDIX G

USGS StreamStats Report

DEWA 10(6) 218(2) DINGMANS FALLS ACCESS BRIDGE #1 StreamStats Report

DINGMANS FALLS ACCESS BRIDGE #1 4320-019P 41.22478889, -74.880033 Rte 218, Dingmans Falls Access

Road

Basin Characteristics

Parameter Code Parameter Description Value Unit

DRNAREA Area that drains to a point on a stream 15.9 square miles

STORAGE Percentage of area of storage (lakes ponds reservoirs wetlands) 10 percent

BSLOPD Mean basin slope measured in degrees 4.7 degrees

BSLOPDRAW Unadjusted basin slope, in degrees 4.87 degrees

CARBON Percentage of area of carbonate rock 0 percent

CENTROXA83 X coordinate of the centroid, in NAD_1983_Albers, meters 256451.8 meters

CENTROYA83 Basin centroid horizontal (y) location in NAD 1983 Albers 254089.5 meters

DRN Drainage quality index from STATSGO 3.9 dimensionless

ELEV Mean Basin Elevation 1174.5 feet

FOREST Percentage of area covered by forest 81 percent

GLACIATED Percentage of basin area that was historically covered by glaciers 100 percent

IMPNLCD01 Percentage of impervious area determined from NLCD 2001 impervious dataset 2 percent

LC01DEV Percentage of land-use from NLCD 2001 classes 21-24 17 percent

LC11DEV Percentage of developed (urban) land from NLCD 2011 classes 21-24 16.9 percent

LC11IMP Average percentage of impervious area determined from NLCD 2011 impervious dataset

1.59 percent

LONG_OUT Longitude of Basin Outlet -74.88022 degrees

MAXTEMP Mean annual maximum air temperature over basin area from PRISM 1971-2000 800-m grid

56 degrees F

OUTLETXA83 X coordinate of the outlet, in NAD_1983_Albers,meters 261495 meters

Region ID: PA Workspace ID: PA20190201201411076000 Clicked Point (Latitude, Longitude): 41.22501, -74.88024 Time: 2019-02-01 15:14:26 -0500

Page 2 of 3StreamStats

2/1/2019https://streamstats.usgs.gov/ss/

Parameter Code Parameter Description Value Unit

OUTLETYA83 Y coordinate of the outlet, in NAD_1983_Albers, meters 251715 meters

PRECIP Mean Annual Precipitation 43 inches

ROCKDEP Depth to rock 5.2 feet

STRDEN Stream Density -- total length of streams divided by drainage area 1.59 miles per square mile

STRMTOT total length of all mapped streams (1:24,000-scale) in the basin 25.31 miles

URBAN Percentage of basin with urban development 7 percent

Peak-Flow Statistics Parameters [Peak Flow Region 1]

Parameter Code Parameter Name Value Units Min Limit Max Limit

DRNAREA Drainage Area 15.9 square miles 1.72 1280

STORAGE Percent Storage 10 percent 0 21.2

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

PIl: Predict ion Interval-Lower, PIu: Prediction Interval-Upper, SEp: Standard Error of Predict ion, SE: Standard Error (other -- see report)

Statistic Value Unit SE SEp Equiv. Yrs.

2 Year Peak Flood 540 ft^3/s 33 33 3

5 Year Peak Flood 932 ft^3/s 31 31 6

10 Year Peak Flood 1260 ft^3/s 31 31 9

50 Year Peak Flood 2150 ft^3/s 36 36 13

100 Year Peak Flood 2610 ft^3/s 38 38 13

500 Year Peak Flood 3910 ft^3/s 46 46 14

Peak-Flow Statistics Citations

Roland, M.A., and Stuckey, M.H.,2008, Regression equations for estimating flood flows at selected recurrence intervals for ungaged streams in Pennsylvania: U.S. Geological Survey Scientific Investigations Report 2008-5102, 57p.

(http://pubs.usgs.gov/sir/2008/5102/)

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.

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: 4.3.0

Page 3 of 3StreamStats

2/1/2019https://streamstats.usgs.gov/ss/

APPENDIX H

SHR-2D Cross Section for WSELs at the entrance of the proposed bridge

APPENDIX I

100-year SRH-2D Stream Profile Plot

APPENDIX J

SHR-2D Floodplain delineation comparison FEMA vs existing vs proposed

National Flood Hazard Layer FIRMette

0 500 1,000 1,500 2,000250 Feet

Ü

SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT

SPECIAL FLOOD

HAZARD AREAS

Without Base Flood Elevation (BFE) Zone A, V, A99

With BFE or DepthZone AE, AO, AH, VE, AR

Regulatory Floodway

0.2% Annual Chance Flood Hazard, Areas of 1% annual chance flood with average depth less than one foot or with drainage areas of less than one square mileZone X

Future Conditions 1% Annual Chance Flood HazardZone X

Area with Reduced Flood Risk due to Levee. See Notes.Zone X

Area with Flood Risk due to LeveeZone D

NO SCREENArea of Minimal Flood HazardZone X

Area of Undetermined Flood HazardZone D

Channel, Culvert, or Storm Sewer

Levee, Dike, or Floodwall

Cross Sections with 1% Annual Chance

17.5 Water Surface Elevation

Coastal Transect

Coastal Transect Baseline Profile Baseline Hydrographic Feature

Base Flood Elevation Line (BFE)

Effective LOMRs

Limit of Study Jurisdiction Boundary

Digital Data Available

No Digital Data Available

Unmapped

This map complies with FEMA's standards for the use of digital flood maps if it is not void as described below.

The basemap shown complies with FEMA's basemap accuracy standards

The flood hazard information is derived directly from the authoritative NFHL web services provided by FEMA. This map was exported on 6/9/2024 at 12:56 PM and does not reflect changes or amendments subsequent to this date and time. The NFHL and effective information may change or become superseded by new data over time.

This map image is void if the one or more of the following map elements do not appear: basemap imagery, flood zone labels, legend, scale bar, map creation date, community identifiers, FIRM panel number, and FIRM effective date. Map images for unmapped and unmodernized areas cannot be used for regulatory purposes.

Legend

OTHER AREAS OF

FLOOD HAZARD

OTHER AREAS

GENERAL

STRUCTURES

OTHER

FEATURES

MAP PANELS

B 20.2

The pin displayed on the map is an approximate point selected by the user and does not represent an authoritative property location.

1:6,000

74°53'7"W 41°13'43"N

74°52'29"W 41°13'16"N

Basemap Imagery Source: USGS National Map 2023

FEMA Floodplain delineation (100‐year) vs SMS Floodplain delineation for existing and proposed conditions

Existing

Floodplain delineated by

SMS

(shaded area)

FEMA Floodplain delineation –

Zone A, No BFE

FEMA Floodplain delineation – Zone A, No BFE (black line)

Proposed

Floodplain delineated by

SMS

(shaded area) isis.rosado-vazquez Line isis.rosado-vazquez Line isis.rosado-vazquez Line isis.rosado-vazquez Line isis.rosado-vazquez Callout SMS Inflow Boundary Condition Q (cfs) (Red line) isis.rosado-vazquez Callout SMS Exit Boundary Condition Rating Curve (Red line) isis.rosado-vazquez Callout SMS Exit Boundary Condition Rating Curve (Red line) isis.rosado-vazquez Callout SMS Inflow Boundary Condition Q (cfs) (Red line) isis.rosado-vazquez Callout Existing Bridge isis.rosado-vazquez Callout Proposed Bridge

APPENDIX K

SHR-2D Upstream and Downstream Cross Section Plots

APPENDIX L

Detailed construction sequence information is available in the E&S plans (M Sheets)

APPENDIX M

Riprap Analysis Report

Riprap Hydraulic Analysis Report

Project Data Project Title: DEWA 10(6) 218 (2) Designer: FHWA/EFL- HYD team Project Date: Saturday, June 8, 2024 Project Units: U.S. Customary Units Notes: Dingman Fall Access Bridge #1, 500-year design storm

Channel Analysis: Channel Analysis Notes:

Input Parameters Channel Type: Custom Cross Section

Cross Section Data Station (ft Elevation (ft) Manning's n

0.00 450.78 0.0400

12.18 450.12 0.0400

15.67 449.91 0.0400

17.52 449.84 0.0400

18.96 449.87 0.0400

24.13 449.70 0.0400

35.85 449.13 0.0400

39.56 449.00 0.0400

43.61 448.52 0.0400

45.15 448.06 0.0400

45.28 448.02 0.0400

45.34 448.00 0.0400

45.60 438.93 0.0400

45.64 437.00 0.0400

45.81 436.91 0.0400

48.80 435.86 0.0400

66.25 435.77 0.0400

69.02 436.04 0.0400

72.91 435.92 0.0400

77.20 435.74 0.0400

80.81 435.77 0.0400

102.02 436.87 0.0400

102.58 436.90 0.0400

103.41 436.95 0.0400

104.25 437.00 0.0400

104.33 442.75 0.0400

104.41 448.28 0.0400

105.65 448.32 0.0400

109.48 448.67 0.0400

111.74 448.70 0.0400

113.88 448.71 0.0400

113.89 448.71 0.0400

115.22 448.71 0.0400

119.40 448.71 0.0400

120.58 448.73 0.0400

121.96 448.78 0.0400

127.10 448.79 0.0400

133.32 448.74 0.0400

138.25 448.81 0.0400

140.99 448.85 0.0400

147.10 448.85 0.0400

148.37 448.87 0.0400

153.98 448.89 0.0400

156.58 448.92 0.0400

156.93 448.92 ----- Longitudinal Slope: 0.0050 ft/ft Flow 3910.0000 cfs

Result Parameters Depth 7.8993 ft Area of Flow 443.5389 ft^2 Wetted Perimeter 72.1489 ft Hydraulic Radius 6.1475 ft Average Velocity 8.8155 ft/s Top Width 58.8779 ft Froude Number: 0.5660 Critical Depth 5.5155 ft Critical Velocity 12.8909 ft/s Critical Slope: 0.0162 ft/ft Critical Top Width 58.77 ft Calculated Max Shear Stress 2.4646 lb/ft^2 Calculated Avg Shear Stress 1.9180 lb/ft^2 Composite Manning's n Equation: Lotter method Manning's n: 0.0400

Riprap Analysis: Riprap Analysis Notes:

Input Parameters Riprap Type: Revetment The channel is a natural channel Local Depth of Flow: 7.89926 ft

Riprap Shape is Angular Stability Coefficient: 0.3 This value is updated by the selected Riprap Shape Blanket Thickness Coefficient: 1 Channel Cross-sectional Average Velocity: 10.05 ft/s Which is the Average Velocity with Spurs Centerline Radius of Curvature of Channel Bend: 1e+09 ft Width of Water Surface at Upstream End of Channel Bend: 58.8779 ft Bank Angle: 1.5 :1 H:V .966 < Bank Angle < 4.011 The location of the revetment protection is on a straight channel Specific Gravity of Riprap: 2.65 Safety Factor: 1.1

Result Parameters Side slope Correction Factor: 0.717953 Velocity Distribution Coefficient: 1 Design Velocity: 10.05 ft/s…