Hydraulic Report - 10.1 WV ERFO FS MNGAH921 2018-1(1) Appendix A.pdf

APPENDIX A

Minor Culverts Analysis

FSR 102 – MP 4.026

DSR 2018-1.1

STA 10+29.14

Hydraulics Report FSR 102 – MP 4.026

WV ERFO FS MNGAH921 2018-1(1) DSR 2018-1.1 – STA 10+29

1. Purpose The purpose of this report is to confirm the proposed pipe size at FSR 102 - MP 4.026 (DSR 2018-1.1 – STA 10+29.14) will meet capacity requirements.

2. Background / Assessment The 2018-1.1 culvert site is located on Public Road 102, about 0.25 miles south of the intersection with Forks of Cranberry Tri (at project STA 10+29). A visual assessment was performed at Site FSR 102 DSR 2018-1.1 in December 2021 by the U.S. Forest Service personnel (Forest Service). The existing culvert that crosses Public Road 102 is an 18” CMP that is buried beneath the gravel roadway. Water flows down a roadside swale toward the pipe which outlets directly into Cranberry River, a stream that runs parallel to the road. Figure 1 shows the conditions of the road and embankment near the location of the culvert and the Cranberry River, at the downstream end of the culvert. The repairs for this site include roadway reconditioning, remove and replace the existing cross pipe and ditch reconditioning. To support the proposed design, a hydraulic HY-8 model was run to confirm the proposed size of the replacement culvert.

Figure 1: Site Pictures. Photos taken December 8, 2021.

3. Hydrology The FSR 102 DSR 2018-1.1 is located within Pocahontas County and has a drainage area of 15.3 acres.

Peak discharges at the project location were calculated using the Rational method. The Rational method is the selected method for estimating peak discharges of drainage areas less than 200 acres. Calculation is based on a simple formula: = , where Q (cfs) is the peak discharges, C is the runoff coefficient, i (in/hr) is the design rainfall intensity, and A (acres) is the drainage area.

Runoff coefficients for various types of land use, hydrologic soil groups and land slopes are provided by West Virginia DOT Drainage Manual. Time of concentration and the drainage area were manually delineated in ESRI GIS using County LIDAR contours and Survey data.

Table 1: Summary of Hydrologic Analysis

Drainage Area (Ac) Runoff Coefficient (C) Tc (min)

15.3 0.25 25.96

Rainfall intensity was read from the NOAA Atlas 14 point precipitation frequency estimates data center with an intensity duration determined based upon the time of concentration.

Peak discharges results are shown in Table 2.

Table 2: Peak Discharge Results

Return Period (year) 25 Peak Discharges (cfs) 13.6

According to Chapter 7 of the PDDM, the design flood standards for culverts are based on roadway classification. This roadway is considered a Low-Standard Road. Cross culverts for this classification are required to convey runoff from the 25-year flood.

4. Hydraulic Modeling The Federal Highway Administrations (FHWA) HY-8 program was used for hydraulic modeling and analysis of the culvert replacement.

4.1. Proposed Conditions

As the length and inverts of the replacement culvert will be adjusted based on field conditions, the purpose of this hydraulic analysis is to confirm the slope and pipe size that will convey the 25-year discharge while meeting PDDM standards.

Tailwater conditions were input based on proposed downstream conditions. Riprap will be placed with a slope of 0.50%. A trapezoidal channel was input with bottom width of 10-feet and side slopes of 5:1 to approximate the conditions of discharge to an open slope. A manning’s n value of 0.055 was assigned to this downstream area.

The culvert data was assigned as a 30” x 19” Elliptical Reinforced Concrete Pipe with manning’ n of 0.012.

The culvert type was set to “Straight”, inlet configuration was set to “Grooved Edge Projecting” and no inlet depression was assigned. Pipe length was input as 20 feet with upstream invert 3190.85, downstream invert 3190.45 with a pipe slope of 2.00%.

The analysis of the 30” x 19” pipe showed that the culvert would backwater under the 25-YR design flow, with a headwater elevation of 3192.50, or a depth of 1.66 feet. Applying a rise of 19-inches (1.58-feet) this results in a headwater to depth ratio of 1.66’/1.58’ = 1.0, satisfying PDDM criteria for a HW/D value less than 1.5 for pipes 48” or less.

The proposed roadway crest elevation is 3194.49 feet, and bottom of aggregate base layer is proposed as

3193.99. The headwater WSEL is less than the bottom of the aggregate base layer, meeting PDDM requirements.

Figure 4: HY-8 Analysis – 42 x 27 RCP at 1% Slope

5. Outlet Protection Riprap should be placed at the culvert outlet in accordance with EFLHD detail E251-01 with slope set to match the existing grade.

6. Design Recommendations At MP 4.026, a 30” x 19” Elliptical Reinforced Concrete Pipe is recommended with a minimum slope of 2.0%. It is recommended that riprap be placed at the culvert outlet in accordance with EFLHD detail E251- 01.

ATTACHMENT

Hydrologic Analysis

13+82

16+89.52

20+28.55

10+29.14

Source: Esri, Maxar, Earthstar Geographics, and the GIS User Community 0 450 900 1,350 1,800225

Feet μ

Legend Drainage Area

SHEET FLOW

SHALLOW CONC. FLOW

CHANNEL FLOW

5-Foot Contours

Project: Designer:

Location: Company:

Date:

Sheet Flow:

Reference Units

Surface Description Woods: Light underbrush Total

Manning's 'n' n HEC-22 Table 4.2 0.400 Flow Length ( 100 ft) L (ft) 100.00

2-Yr, 24-Hr Rainfall

P2

NOAA Atlas 14 Locally determined depth

(in) 2.76

Upstream elevation E1 (ft) 4052.00 Downstream elevation E2 (ft) 4050.00 Land slope S (E1-E2)/L (ft/ft) 0.020 Travel time - Sheetflow TSH HEC-22 Eqn 4.3 (min) 23.12 23.12

Reference Units

Surface Description

Unpaved (shallow concentrate d flow)

Intercept Coefficient, k HEC-22 Table 4.3 0.49 Flow Length L (ft) 3613.12 Upstream elevation E1 (ft) 4050.00 Downstream elevation E2 (ft) 3187.47 Watercourse Slope (0.005 ft/ft min.) S (E1-E2)/L % 24%

Average Velocity V HEC-22 Eqn 4.4 (ft/s) 7.869

Travel Time TSC HEC-22 Eqn 4.6 (min) 7.65 7.65

Channel Flow:

Reference Units

Channel Shape Triangular Flow Depth or Pipe Diameter D (ft) Channel Top Width WT (ft) 3.0

Average Channel Side Slope Z:1 Trapezoidal Channel only

Approximate Channel Bottom WB

Trapezoidal Channel only (ft) 0.0

Cross Sectional Flow Area A (ft) Wetted Perimeter Pw (ft) Hydraulic Radius R A/PW (ft) Upstream elevation E1 (ft) Downstream elevation E2 (ft) Channel Slope, s S (E1-E2)/L (ft/ft)

Channel Material

Ditch - Brush/Unmai ntained Manning's 'n' n 0.080 Velocity V HEC-22 Eqn 4.5 (ft/s) Flow Length L (ft) Travel time TCH HEC-22 Eqn 4.6 (min) 0.0

Watershed Time of Concentration or Travel Time (min) = 30.78

Compute Time of Concentration (Tc) or Travel Time (Tt)

Shallow Concentrated Flow:

Time of Concentration Worksheet

MNGHA MTC

2018-1.1 STA 13+82 WSP

7/15/2025

Point precipitation frequency estimates (inches/hour) NOAA Atlas 14 Volume 2 Version 3 Data type: Precipitation intensity Time series type: Partial duration Project area: Ohio River Basin Location na West Virgi USA Station Name: - Latitude: 38.2520 Degree Longitude: -80.3201 Degree Elevation (USGS): 3194 ft

PRECIPITATION FREQUENCY ESTIMATES

by duration 1 2 5 10 25 50 100 200 500 1000 5-min: 3.64 4.36 5.2 5.8 6.54 7.07 7.57 8.04 8.6 9.04 5 10-min: 2.9 3.47 4.15 4.63 5.2 5.61 5.99 6.35 6.79 7.09 10 15-min: 2.41 2.91 3.5 3.9 4.39 4.73 5.04 5.34 5.7 5.94 15 30-min: 1.65 2 2.48 2.82 3.24 3.55 3.85 4.14 4.51 4.78 30 60-min: 1.03 1.26 1.59 1.83 2.16 2.4 2.65 2.9 3.23 3.49 60 2-hr: 0.627 0.768 0.966 1.12 1.31 1.47 1.63 1.8 2.02 2.2 120 3-hr: 0.454 0.554 0.692 0.799 0.944 1.06 1.18 1.31 1.48 1.62 180 6-hr: 0.278 0.336 0.416 0.48 0.57 0.643 0.72 0.803 0.92 1.02 12-hr: 0.168 0.202 0.248 0.287 0.343 0.39 0.441 0.496 0.577 0.646 24-hr: 0.097 0.115 0.139 0.158 0.185 0.206 0.228 0.251 0.292 0.328 2-day: 0.058 0.069 0.082 0.093 0.108 0.119 0.131 0.143 0.159 0.172 3-day: 0.043 0.051 0.06 0.068 0.078 0.086 0.093 0.102 0.113 0.121 4-day: 0.035 0.042 0.049 0.055 0.063 0.069 0.075 0.081 0.089 0.096 7-day: 0.025 0.03 0.035 0.039 0.044 0.048 0.051 0.055 0.06 0.064 10-day: 0.02 0.024 0.028 0.031 0.035 0.038 0.041 0.044 0.047 0.05 20-day: 0.015 0.017 0.02 0.022 0.024 0.026 0.028 0.03 0.032 0.034 30-day: 0.013 0.015 0.017 0.018 0.02 0.022 0.023 0.024 0.026 0.027 45-day: 0.011 0.013 0.014 0.016 0.017 0.018 0.019 0.02 0.021 0.022 60-day: 0.01 0.012 0.013 0.014 0.015 0.016 0.017 0.018 0.018 0.019

Date/time (GMT): Tue Jul 15 20:32:16 2025 pyRunTime: 0.007939577102661133

Date:

46.3 0.25

30.78

2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 200-yr 500-yr

1.98 2.46 2.79 3.21 3.52 3.82 4.11 4.48

2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 200-yr 500-yr

22.9 28.4 32.3 37.2 40.7 44.2 47.5 51.8

Interpolated Rainfall Intensity, I (in/hr)

Peak Flow, Q (cfs)

Forested C/D Soils

Notes

Computed Tc (min) See Tc Worksheet

Compute Peak Flow Rates

Rational Method Worksheet

Area (ac) Runoff Coefficient

MNGHA

2018-1.1 STA 13+82

MTC

WSP

HEC-22 Eqn 4.1

HY-8 Report

HY-8 Culvert Analysis Report

Table 1 - Project Headwater Table Crossing Name

Culvert Name

Total Discharge (cfs)

Culvert Discharge (cfs)

Headwater Elevation (ft)

Inlet Control Depth (ft)

Outlet Control Depth (ft)

HW / D

(ft)

Normal Depth (ft)

Critical Depth (ft)

Outlet Depth (ft)

Outlet Velocity (ft/s)

2018-1.1 10+29.14 100%

Culvert

13.60 13.60 3192.50 1.65 1.105 1.04 0.69 1.11 0.82 8.14

Crossing Input: 2018-1.1 10+29.14 100% Parameter Value Units

DISCHARGE DATA

Discharge Method Minimum, Design, and

Maximum Minimum Flow 1.000 cfs Design Flow 13.600 cfs Maximum Flow 16.000 cfs

TAILWATER DATA

Channel Type Trapezoidal Channel Bottom Width 10.000 ft Side Slope (H:V) 5.000 _:1 Channel Slope 0.0050 ft/ft Manning's n (channel) 0.055 Channel Invert Elevation 3190.450 ft Rating Curve View...

ROADWAY DATA

Roadway Profile Shape Constant Roadway

Elevation First Roadway Station 0.000 ft Crest Length 100.000 ft Crest Elevation 3194.490 ft Roadway Surface Gravel Top Width 12.000 ft

Culvert Input: 2018-1.1 10+29.14 100% Parameter Value Units

CULVERT DATA

Name Culvert 1 Shape Elliptical Material Concrete Size Define...

Span 30.000 in Rise 19.000 in Embedment Depth 0.000 in Manning's n 0.012 Culvert Type Straight Inlet Configuration Grooved Edge Projecting

(Ke=0.2) Inlet Depression? No

SITE DATA

Site Data Input Option Culvert Invert Data Inlet Station 0.000 ft Inlet Elevation 3190.850 ft Outlet Station 20.000 ft Outlet Elevation 3190.450 ft Number of Barrels 1 Computed Culvert Slope 0.020000 ft/ft

Table 2 - Culvert Summary Table: Culvert 1 Total Discharge (cfs)

Culvert Discharge (cfs)

Headwater Elevation (ft)

Inlet Control Depth (ft)

Outlet Control Depth (ft)

HW

/ D (ft)

Flow Type

Normal Depth (ft)

Critical Depth (ft)

Outlet Depth (ft)

Tailwater Depth (ft)

Outlet Velocity (ft/s)

Tailwater Velocity (ft/s)

1.00 1.00 3191.21 0.36 0.0* 0.23 1-S2n 0.19 0.28 0.19 0.17 4.27 0.55

2.50 2.50 3191.43 0.58 0.060 0.37 1-S2n 0.29 0.45 0.31 0.29 5.47 0.76

4.00 4.00 3191.60 0.75 0.206 0.47 1-S2n 0.37 0.57 0.40 0.38 6.13 0.90

5.50 5.50 3191.78 0.93 0.343 0.59 1-S2n 0.43 0.68 0.48 0.45 6.59 1.00

7.00 7.00 3191.94 1.09 0.478 0.69 1-S2n 0.48 0.77 0.55 0.52 6.97 1.08

8.50 8.50 3192.08 1.23 0.614 0.78 1-S2n 0.53 0.86 0.61 0.57 7.29 1.15

10.00 10.00 3192.21 1.36 0.753 0.86 1-S2n 0.58 0.94 0.68 0.63 7.57 1.21

11.50 11.50 3192.33 1.48 0.896 0.93 1-S2n 0.63 1.01 0.74 0.68 7.82 1.26

13.60 13.60 3192.50 1.65 1.105 1.04 5-S2n 0.69 1.11 0.82 0.74 8.14 1.33

14.50 14.50 3192.57 1.72 1.197 1.09 5-S2n 0.71 1.15 0.85 0.77 8.27 1.36

16.00 16.00 3192.71 1.86 1.544 1.17 5-S2n 0.75 1.21 0.91 0.81 8.48 1.40

30.55 29.01 3194.52 3.67 2.947 2.32 5-S2n 1.09 1.50 1.29 1.15 10.44 1.69

* Full Flow Headwater elevation is below inlet invert.

Water Surface Profile Plot for Culvert: Culvert 1

FSR 102 – MP 4.026

DSR 2018-1.1

STA 13+82.08

WV ERFO FS MNGAH921 2018-1(1) DSR 2018-1.1 – STA 13+82

1. Purpose The purpose of this report is to confirm the proposed pipe size at FSR 102 - MP 4.026 (DSR 2018-1.1 – STA 13+82) will meet capacity requirements.

2. Background / Assessment The 2018-1.1 culvert site is located on Public Road 102, about 0.25 miles south of the intersection with Forks of Cranberry Tri (at project STA 13+82). A visual assessment was performed at Site FSR 102 DSR 2018-1.1 in December 2021 by the U.S. Forest Service personnel (Forest Service). The existing culvert that crosses Public Road 102 is an 18” CMP that is buried beneath the gravel roadway. Water flows down a roadside swale toward the pipe which outlets directly into Cranberry River, a stream that runs parallel to the road. Figure 1 shows the conditions of the road and embankment near the location of the culvert and the Cranberry River, at the downstream end of the culvert. The repairs for this site include roadway reconditioning, remove and replace the existing cross pipe and ditch reconditioning. To support the proposed design, a hydraulic HY-8 model was run to confirm the proposed size of the replacement culvert.

The FSR 102 DSR 2018-1.1 is located within Pocahontas County and has a drainage area of 46.3 acres.

Peak discharges at the project location were calculated using the Rational method. The Rational method is the selected method for estimating peak discharges of drainage areas less than 200 acres. Calculation is based on a simple formula: = , where Q (cfs) is the peak discharges, C is the runoff coefficient, i (in/hr) is the design rainfall intensity, and A (acres) is the drainage area.

Runoff coefficients for various types of land use, hydrologic soil groups and land slopes are provided by West Virginia DOT Drainage Manual. Time of concentration and the drainage area were manually delineated in ESRI GIS using County LIDAR contours and Survey data.

Table 1: Summary of Hydrologic Analysis

Drainage Area (Ac) Runoff Coefficient (C) Tc (min)

46.3 0.25 30.8

Rainfall intensity was read from the NOAA Atlas 14 point precipitation frequency estimates data center

Peak discharges results are shown in Table 2.

Table 2: Peak Discharge Results

Return Period (year) 25 Peak Discharges (cfs) 37.2

According to Chapter 7 of the PDDM, the design flood standards for culverts are based on roadway classification. This roadway is considered a Low-Standard Road. Cross culverts for this classification are required to convey runoff from the 25-year flood.

4. Hydraulic Modeling The Federal Highway Administrations (FHWA) HY-8 program was used for hydraulic modeling and analysis of the culvert replacement.

4.1. Proposed Conditions

As the length and inverts of the replacement culvert will be adjusted based on field conditions, the purpose of this hydraulic analysis is to confirm the slope and pipe size that will convey the 25-year discharge while meeting PDDM standards.

Tailwater conditions were input based on proposed downstream conditions. Riprap will be placed with a slope of 7H:1V. A trapezoidal channel was input with bottom width of 10-feet and side slopes of 5:1 to approximate the conditions of discharge to an open slope. A manning’s n value of 0.055 was assigned to this downstream area.

The culvert data was assigned as a 42” x 27” Elliptical Reinforced Concrete Pipe with manning’ n of 0.012.

The culvert type was set to “Straight”, inlet configuration was set to “Grooved Edge Projecting” and no inlet depression was assigned. Pipe length was input as 22 feet with upstream invert 3187.47, downstream invert 3187.03 with a pipe slope of 2.00%.

The analysis of the 42” x 27” pipe showed that the culvert would backwater under the 25-YR design flow, with a headwater elevation of 3190.08, or a depth of 2.61 feet. Applying a rise of 27-inches (2.25-feet) this results in a headwater to depth ratio of 2.61’/2.25’ = 1.0, satisfying PDDM criteria for a HW/D value less than 1.5 for pipes 48” or less.

The proposed roadway crest elevation is 3191.38 feet, and bottom of aggregate base layer is proposed as

3190.88. The headwater WSEL is less than the bottom of the aggregate base layer, meeting PDDM

Figure 4: HY-8 Analysis – 30 x 19 RCP at 2.0% Slope

5. Outlet Protection Riprap should be placed at the culvert outlet in accordance with EFLHD detail E251-01 with slope set to match the existing grade.

6. Design Recommendations At MP 4.026, a 42” x 27” Elliptical Reinforced Concrete Pipe is recommended with a minimum slope of 2.0%. It is recommended that riprap be placed at the culvert outlet in accordance with EFLHD detail E251-

20+28.55

10+29.14

Source: Esri, Maxar, Earthstar Geographics, and the GIS User Community 0 450 900 1,350 1,800225

Feet μ

Legend Drainage Area

SHEET FLOW

SHALLOW CONC. FLOW

Date:

Sheet Flow:

Reference Units

Surface Description Woods: Light underbrush Total

Manning's 'n' n HEC-22 Table 4.2 0.400 Flow Length ( 100 ft) L (ft) 100.00

2-Yr, 24-Hr Rainfall

P2

NOAA Atlas 14 Locally determined depth

(in) 2.76

Upstream elevation E1 (ft) 4052.00 Downstream elevation E2 (ft) 4050.00 Land slope S (E1-E2)/L (ft/ft) 0.020 Travel time - Sheetflow TSH HEC-22 Eqn 4.3 (min) 23.12 23.12

Reference Units

Surface Description

Unpaved (shallow concentrate d flow)

Intercept Coefficient, k HEC-22 Table 4.3 0.49 Flow Length L (ft) 3613.12 Upstream elevation E1 (ft) 4050.00 Downstream elevation E2 (ft) 3187.47 Watercourse Slope (0.005 ft/ft min.) S (E1-E2)/L % 24%

Average Velocity V HEC-22 Eqn 4.4 (ft/s) 7.869

Travel Time TSC HEC-22 Eqn 4.6 (min) 7.65 7.65

Channel Flow:

Reference Units

Channel Shape Triangular Flow Depth or Pipe Diameter D (ft) Channel Top Width WT (ft) 3.0

Average Channel Side Slope Z:1 Trapezoidal Channel only

Approximate Channel Bottom WB

Trapezoidal Channel only (ft) 0.0

Cross Sectional Flow Area A (ft) Wetted Perimeter Pw (ft) Hydraulic Radius R A/PW (ft) Upstream elevation E1 (ft) Downstream elevation E2 (ft) Channel Slope, s S (E1-E2)/L (ft/ft)

Channel Material

Ditch - Brush/Unmai ntained Manning's 'n' n 0.080 Velocity V HEC-22 Eqn 4.5 (ft/s) Flow Length L (ft) Travel time TCH HEC-22 Eqn 4.6 (min) 0.0

Watershed Time of Concentration or Travel Time (min) = 30.78

Compute Time of Concentration (Tc) or Travel Time (Tt)

Shallow Concentrated Flow:

Time of Concentration Worksheet

MNGHA MTC

2018-1.1 STA 13+82 WSP

Data type: Precipitation intensity Time series type: Partial duration Project area: Ohio River Basin Location na West Virgi USA Station Name: - Latitude: 38.2520 Degree Longitude: -80.3201 Degree Elevation (USGS): 3194 ft

PRECIPITATION FREQUENCY ESTIMATES

by duration 1 2 5 10 25 50 100 200 500 1000 5-min: 3.64 4.36 5.2 5.8 6.54 7.07 7.57 8.04 8.6 9.04 5 10-min: 2.9 3.47 4.15 4.63 5.2 5.61 5.99 6.35 6.79 7.09 10 15-min: 2.41 2.91 3.5 3.9 4.39 4.73 5.04 5.34 5.7 5.94 15 30-min: 1.65 2 2.48 2.82 3.24 3.55 3.85 4.14 4.51 4.78 30 60-min: 1.03 1.26 1.59 1.83 2.16 2.4 2.65 2.9 3.23 3.49 60 2-hr: 0.627 0.768 0.966 1.12 1.31 1.47 1.63 1.8 2.02 2.2 120 3-hr: 0.454 0.554 0.692 0.799 0.944 1.06 1.18 1.31 1.48 1.62 180 6-hr: 0.278 0.336 0.416 0.48 0.57 0.643 0.72 0.803 0.92 1.02 12-hr: 0.168 0.202 0.248 0.287 0.343 0.39 0.441 0.496 0.577 0.646 24-hr: 0.097 0.115 0.139 0.158 0.185 0.206 0.228 0.251 0.292 0.328 2-day: 0.058 0.069 0.082 0.093 0.108 0.119 0.131 0.143 0.159 0.172 3-day: 0.043 0.051 0.06 0.068 0.078 0.086 0.093 0.102 0.113 0.121 4-day: 0.035 0.042 0.049 0.055 0.063 0.069 0.075 0.081 0.089 0.096 7-day: 0.025 0.03 0.035 0.039 0.044 0.048 0.051 0.055 0.06 0.064 10-day: 0.02 0.024 0.028 0.031 0.035 0.038 0.041 0.044 0.047 0.05 20-day: 0.015 0.017 0.02 0.022 0.024 0.026 0.028 0.03 0.032 0.034 30-day: 0.013 0.015 0.017 0.018 0.02 0.022 0.023 0.024 0.026 0.027 45-day: 0.011 0.013 0.014 0.016 0.017 0.018 0.019 0.02 0.021 0.022 60-day: 0.01 0.012 0.013 0.014 0.015 0.016 0.017 0.018 0.018 0.019

Date:

46.3 0.25

30.78

2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 200-yr 500-yr

1.98 2.46 2.79 3.21 3.52 3.82 4.11 4.48

2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 200-yr 500-yr

22.9 28.4 32.3 37.2 40.7 44.2 47.5 51.8

Interpolated Rainfall Intensity, I (in/hr)

Peak Flow, Q (cfs)

Forested C/D Soils

Notes

Computed Tc (min) See Tc Worksheet

Compute Peak Flow Rates

Rational Method Worksheet

Area (ac) Runoff Coefficient

MNGHA

2018-1.1 STA 13+82

MTC

WSP

Crossing Name

Culvert Name

Total Discharge (cfs)

Culvert Discharge (cfs)

Headwater Elevation (ft)

Inlet Control Depth (ft)

Outlet Control Depth (ft)

HW / D

(ft)

Normal Depth (ft)

Critical Depth (ft)

Outlet Depth (ft)

Outlet Velocity (ft/s)

2018-1.1 10+29.14 100%

Culvert

13.60 13.60 3192.50 1.65 1.105 1.04 0.69 1.11 0.82 8.14

Crossing Input: 2018-1.1 10+29.14 100%

DISCHARGE DATA

Discharge Method Minimum, Design, and

Maximum Minimum Flow 1.000 cfs Design Flow 13.600 cfs Maximum Flow 16.000 cfs

TAILWATER DATA

Channel Type Trapezoidal Channel Bottom Width 10.000 ft Side Slope (H:V) 5.000 _:1 Channel Slope 0.0050 ft/ft Manning's n (channel) 0.055 Channel Invert Elevation 3190.450 ft Rating Curve View...

ROADWAY DATA

Roadway Profile Shape Constant Roadway

Elevation First Roadway Station 0.000 ft Crest Length 100.000 ft Crest Elevation 3194.490 ft Roadway Surface Gravel Top Width 12.000 ft

Culvert Input: 2018-1.1 10+29.14 100% Parameter Value Units

CULVERT DATA

Name Culvert 1 Shape Elliptical Material Concrete Size Define...

Span 30.000 in Rise 19.000 in Embedment Depth 0.000 in Manning's n 0.012 Culvert Type Straight Inlet Configuration Grooved Edge Projecting

(Ke=0.2) Inlet Depression? No

SITE DATA

Site Data Input Option Culvert Invert Data Inlet Station 0.000 ft Inlet Elevation 3190.850 ft Outlet Station 20.000 ft Outlet Elevation 3190.450 ft

Discharge (cfs)

Culvert Discharge (cfs)

Headwater Elevation (ft)

Inlet Control Depth (ft)

Outlet Control Depth (ft)

HW

/ D (ft)

Flow Type

Normal Depth (ft)

Critical Depth (ft)

Outlet Depth (ft)

Tailwater Depth (ft)

Outlet Velocity (ft/s)

Tailwater Velocity (ft/s)

1.00 1.00 3191.21 0.36 0.0* 0.23 1-S2n 0.19 0.28 0.19 0.17 4.27 0.55

2.50 2.50 3191.43 0.58 0.060 0.37 1-S2n 0.29 0.45 0.31 0.29 5.47 0.76

4.00 4.00 3191.60 0.75 0.206 0.47 1-S2n 0.37 0.57 0.40 0.38 6.13 0.90

5.50 5.50 3191.78 0.93 0.343 0.59 1-S2n 0.43 0.68 0.48 0.45 6.59 1.00

7.00 7.00 3191.94 1.09 0.478 0.69 1-S2n 0.48 0.77 0.55 0.52 6.97 1.08

8.50 8.50 3192.08 1.23 0.614 0.78 1-S2n 0.53 0.86 0.61 0.57 7.29 1.15

10.00 10.00 3192.21 1.36 0.753 0.86 1-S2n 0.58 0.94 0.68 0.63 7.57 1.21

11.50 11.50 3192.33 1.48 0.896 0.93 1-S2n 0.63 1.01 0.74 0.68 7.82 1.26

13.60 13.60 3192.50 1.65 1.105 1.04 5-S2n 0.69 1.11 0.82 0.74 8.14 1.33

14.50 14.50 3192.57 1.72 1.197 1.09 5-S2n 0.71 1.15 0.85 0.77 8.27 1.36

16.00 16.00 3192.71 1.86 1.544 1.17 5-S2n 0.75 1.21 0.91 0.81 8.48 1.40

30.55 29.01 3194.52 3.67 2.947 2.32 5-S2n 1.09 1.50 1.29 1.15 10.44 1.69

FSR 102 – MP 2.618

DSR 2018-1.2

STA 20+11.41

Hydraulics Report FSR 102 – MP 2.618

WV ERFO FS MNGAH921 2018-1(1) DSR 2018-1.2 – STA 20+11.41

1. Purpose The purpose of this report is to confirm the proposed pipe size at FSR 102 - MP 2.618 (DSR 2018-1.2 – STA 20+11.41) will meet capacity requirements.

2. Background / Assessment The 2018_1.02 culvert site is located on Public Road 102, about 0.44 miles south of the intersection with Lost Run. A visual assessment was performed at Site FSR 102 DSR 2018-1.02 in December 2021 by performed by the U.S. Forest Service personnel (Forest Service). The existing culvert that crosses Public Road 102 is an 18” CMP that is buried beneath the gravel roadway. Water flows down a roadside swale toward the pipe which outlets directly into Cranberry River, a stream that runs parallel to the road. Figure 1 shows the conditions of the road and embankment near the location of the culvert and the Cranberry River, at the downstream end of the culvert. The scopes for this site are: embankment repairs with special rock embankment (riprap) and geotextile lining, roadway reconditioning, aggregate surface, remove and replace existing cross pipe, ditch reconditioning, shoulder reconstruction.

The FSR 102 DSR 2018-1.2 is located within Pocahontas County and has a drainage area of 4.26 acres.

Peak discharges at the project location were calculated using the Rational method. The Rational method is the selected method for estimating peak discharges of drainage areas less than 200 acres. Calculation is based on a simple formula: = , where Q (cfs) is the peak discharges, C is the runoff coefficient, i (in/hr) is the design rainfall intensity, and A (acres) is the drainage area.

Runoff coefficients for various types of land use, hydrologic soil groups and land slopes are provided by West Virginia DOT Drainage Manual. Time of concentration and the drainage area were manually delineated in ESRI GIS using County LIDAR contours and Survey data.

Table 1: Summary of Hydrologic Analysis

4.26 0.35 23.54

Rainfall intensity was read from the NOAA Atlas 14 point precipitation frequency estimates data center

Hydraulics Report FSR 102 – MP 2.654

Peak discharges results are shown in Table 2.

Table 2: Peak Discharge Results Return Period (year) 25

Peak Discharges (cfs) 5.6

According to Chapter 7 of the PDDM, the design flood standards for culverts are based on roadway classification. This roadway is considered a Low-Standard Road. Cross culverts for this classification are required to convey runoff from the 25-year flood.

4. Hydraulic Modeling The Federal Highway Administrations (FHWA) HY-8 program was used for hydraulic modeling and analysis of the culvert replacement.

4.1. Proposed Conditions

As the length and inverts of the replacement culvert will be adjusted based on field conditions, the purpose of this hydraulic analysis is to confirm the slope and pipe size that will convey the 25-year discharge while meeting PDDM standards.

Tailwater conditions were input based on proposed downstream conditions. The riprap will be placed with a slope of approximately 0.05%. A trapezoidal channel was input with bottom width of 10-feet and side slopes of 5:1 to approximate the conditions of discharge to an open slope. A manning’s n value of 0.055 was assigned to this downstream area.

The culvert data was assigned as a 30” x 19” Elliptical Reinforced Concrete Pipe with manning’ n of 0.012.

The culvert type was set to “Straight”, inlet configuration was set to “Grooved Edge Projecting” and no inlet depression was assigned. Pipe length was input as 23 feet with upstream invert 3284.37, downstream invert 3283.91 with a pipe slope of 2.0%.

The analysis of the 30” x 19” pipe showed that the culvert can convey the 25-YR design flow, with a headwater elevation of 3285.31, or a depth of 0.94 feet, this results in a headwater to depth ratio of 0.94’/1.58’ = 0.6, satisfying PDDM criteria for a HW/D value less than 1.5 for pipes 48” or less.

The proposed roadway crest elevation is 3287.87 feet, and the bottom of aggregate base layer is proposed as 3287.37. The headwater WSEL is less than the bottom of the aggregate base layer, meeting PDDM

Hydraulics Report FSR 102 – MP 2.654

Figure 4: HY-8 Analysis – 30 x 19 RCP at 2.0% Slope

5. Outlet Protection Riprap should be placed at the culvert outlet in accordance with EFLHD detail E251-01 with slope set to match the existing grade.

6. Design Recommendations At MP 2.654, a 30” x 19” Elliptical Reinforced Concrete Pipe is recommended with a minimum slope of 2.0%. It is recommended that riprap be placed at the culvert outlet in accordance with EFLHD detail E251-

23+15.25 20+11.41

Source: Esri, Maxar, Earthstar 0 180 360 540 72090

Feet μ

Legend Drainage Area

SHEET FLOW

SHALLOW CONC. FLOW

2-Foot Contours

Date:

Sheet Flow:

Reference Units

Surface Description Woods: Light underbrush Total

Manning's 'n' n HEC-22 Table 4.2 0.400 Flow Length ( 100 ft) L (ft) 100.00

2-Yr, 24-Hr Rainfall

P2

NOAA Atlas 14 Locally determined depth

(in) 2.76

Upstream elevation E1 (ft) 3830.00 Downstream elevation E2 (ft) 3827.30 Land slope S (E1-E2)/L (ft/ft) 0.027 Travel time - Sheetflow TSH HEC-22 Eqn 4.3 (min) 20.51 20.51

Reference Units

Surface Description

Unpaved (shallow concentrate d flow)

Intercept Coefficient, k HEC-22 Table 4.3 0.49 Flow Length L (ft) 1292.00 Upstream elevation E1 (ft) 3827.30 Downstream elevation E2 (ft) 3377.70 Watercourse Slope (0.005 ft/ft min.) S (E1-E2)/L % 35%

Average Velocity V HEC-22 Eqn 4.4 (ft/s) 9.500

Travel Time TSC HEC-22 Eqn 4.6 (min) 2.27 2.27

Channel Flow:

Reference Units

Channel Shape Triangular Flow Depth or Pipe Diameter D (ft) 1.0 Channel Top Width WT (ft) 3.0

Average Channel Side Slope Z:1 Trapezoidal Channel only

Approximate Channel Bottom WB

Trapezoidal Channel only (ft) 0.0

Cross Sectional Flow Area A (ft) 1.5

Wetted Perimeter Pw (ft) 3.6 Hydraulic Radius R A/PW (ft) 0.4 Upstream elevation E1 (ft) 3377.70 Downstream elevation E2 (ft) 3284.15 Channel Slope, s S (E1-E2)/L (ft/ft) 0.337

Channel Material

Ditch - Brush/Unmai ntained Manning's 'n' n 0.080 Velocity V HEC-22 Eqn 4.5 (ft/s) 6.021 Flow Length L (ft) 278.00 Travel time TCH HEC-22 Eqn 4.6 (min) 0.77 0.8

Watershed Time of Concentration or Travel Time (min) = 23.54

Compute Time of Concentration (Tc) or Travel Time (Tt)

Shallow Concentrated Flow:

Time of Concentration Worksheet

MNGHA LL

2018-1.2 STA 20+11.41 WSP

Data type: Precipitation intensity Time series type: Partial duration Project area: Ohio River Basin Location na West Virgi USA Station Name: - Latitude: 38.2379 Degree Longitude: -80.3069 Degree Elevation (USGS): 3281 ft

PRECIPITATION FREQUENCY ESTIMATES

by duration 1 2 5 10 25 50 100 200 500 1000 5-min: 3.61 4.33 5.16 5.77 6.53 7.04 7.55 8.02 8.58 9 5 10-min: 2.89 3.46 4.14 4.61 5.18 5.59 5.98 6.34 6.76 7.06 10 15-min: 2.4 2.9 3.48 3.88 4.38 4.72 5.03 5.32 5.67 5.9 15 30-min: 1.65 2 2.47 2.81 3.23 3.54 3.84 4.13 4.5 4.76 30 60-min: 1.02 1.25 1.58 1.83 2.15 2.4 2.64 2.89 3.22 3.47 60 2-hr: 0.631 0.774 0.972 1.12 1.32 1.48 1.64 1.81 2.03 2.22 120 3-hr: 0.456 0.557 0.697 0.803 0.949 1.06 1.19 1.31 1.48 1.63 180 6-hr: 0.279 0.337 0.418 0.481 0.571 0.644 0.722 0.804 0.921 1.02 12-hr: 0.168 0.201 0.248 0.287 0.343 0.39 0.441 0.496 0.576 0.645 24-hr: 0.097 0.116 0.139 0.159 0.186 0.207 0.23 0.253 0.292 0.327 2-day: 0.059 0.069 0.083 0.094 0.108 0.12 0.132 0.144 0.161 0.174 3-day: 0.043 0.051 0.06 0.068 0.078 0.086 0.094 0.102 0.113 0.122 4-day: 0.035 0.042 0.049 0.055 0.063 0.069 0.075 0.081 0.09 0.096 7-day: 0.025 0.03 0.035 0.039 0.044 0.048 0.052 0.055 0.061 0.065 10-day: 0.021 0.024 0.028 0.031 0.035 0.038 0.041 0.044 0.048 0.051 20-day: 0.015 0.017 0.02 0.022 0.024 0.026 0.028 0.03 0.032 0.034 30-day: 0.013 0.015 0.017 0.018 0.02 0.022 0.023 0.024 0.026 0.027 45-day: 0.011 0.013 0.014 0.016 0.017 0.018 0.019 0.02 0.022 0.023 60-day: 0.01 0.012 0.013 0.014 0.015 0.016 0.017 0.018 0.019 0.019

Date/time (GMT): Thu Jul 17 15:22:16 2025 pyRunTime: 0.0076296329498291016

Date:

4.26 0.35

23.54

2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 200-yr 500-yr

2.39 2.90 3.27 3.73 4.05 4.35 4.64 5.00

2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 200-yr 500-yr

3.6 4.3 4.9 5.6 6.0 6.5 6.9 7.5

Compute Peak Flow Rates

Rational Method Worksheet

Area (ac) Runoff Coefficient

MNGHA

2018-1.2 STA 20+11.41

LL

WSP

7/15/2025

Interpolated Rainfall Intensity, I (in/hr)

Peak Flow, Q (cfs)

Forested C/D Soils

Notes

Computed Tc (min) See Tc Worksheet

Crossing Name

Culvert Name

Total Discharge (cfs)

Culvert Discharge (cfs)

Headwater Elevation (ft)

Inlet Control Depth (ft)

Outlet Control Depth (ft)

HW / D

(ft)

Normal Depth (ft)

Critical Depth (ft)

Outlet Depth (ft)

Outlet Velocity (ft/s)

2018-1.2 20+11.41 100%

Culvert

5.60 5.60 3285.31 0.94 0.468 0.59 0.43 0.68 0.47 6.75

Crossing Input: 2018-1.2 20+11.41 100%

DISCHARGE DATA

Discharge Method Minimum, Design, and

Maximum Minimum Flow 1.000 cfs Design Flow 5.600 cfs Maximum Flow 6.500 cfs

TAILWATER DATA

Channel Type Trapezoidal Channel Bottom Width 10.000 ft Side Slope (H:V) 5.000 _:1 Channel Slope 0.0005 ft/ft Manning's n (channel) 0.055 Channel Invert Elevation 3283.910 ft Rating Curve View...

ROADWAY DATA

Roadway Profile Shape Constant Roadway

Elevation First Roadway Station 0.000 ft Crest Length 100.000 ft Crest Elevation 3287.870 ft Roadway Surface Gravel Top Width 12.000 ft

Culvert Input: 2018-1.2 20+11.41 100% Parameter Value Units

CULVERT DATA

Name Culvert 1 Shape Elliptical Material Concrete Size Define...

Span 30.000 in Rise 19.000 in Embedment Depth 0.000 in Manning's n 0.012 Culvert Type Straight Inlet Configuration Grooved Edge Projecting

(Ke=0.2) Inlet Depression? No

SITE DATA

Site Data Input Option Culvert Invert Data Inlet Station 0.000 ft Inlet Elevation 3284.370 ft Outlet Station 23.000 ft Outlet Elevation 3283.910 ft

Discharge (cfs)

Culvert Discharge (cfs)

Headwater Elevation (ft)

Inlet Control Depth (ft)

Outlet Control Depth (ft)

HW

/ D (ft)

Flow Type

Normal Depth (ft)

Critical Depth (ft)

Outlet Depth (ft)

Tailwater Depth (ft)

Outlet Velocity (ft/s)

Tailwater Velocity (ft/s)

1.00 1.00 3284.73 0.36 0.0* 0.23 1-S2n 0.19 0.28 0.19 0.33 4.28 0.26

1.55 1.55 3284.82 0.45 0.0* 0.28 1-S2n 0.23 0.35 0.24 0.42 4.86 0.30

2.10 2.10 3284.90 0.53 0.050 0.33 1-S2n 0.27 0.41 0.28 0.50 5.30 0.34

2.65 2.65 3284.97 0.60 0.125 0.38 1-S2n 0.30 0.46 0.31 0.57 5.63 0.36

3.20 3.20 3285.03 0.66 0.196 0.42 1-S2n 0.33 0.51 0.35 0.63 5.90 0.38

3.75 3.75 3285.09 0.72 0.262 0.46 1-S2n 0.35 0.55 0.38 0.69 6.14 0.40

4.30 4.30 3285.15 0.78 0.325 0.49 1-S2n 0.38 0.59 0.41 0.74 6.34 0.42

4.85 4.85 3285.22 0.85 0.387 0.54 1-S2n 0.40 0.63 0.44 0.80 6.52 0.44

5.60 5.60 3285.31 0.94 0.468 0.59 1-S2n 0.43 0.68 0.47 0.86 6.75 0.46

5.95 5.95 3285.35 0.98 0.506 0.62 1-S2n 0.45 0.71 0.49 0.89 6.84 0.46

6.50 6.50 3285.41 1.04 0.564 0.66 1-S2n 0.47 0.74 0.52 0.93 6.98 0.48

28.95 28.18 3287.89 3.52 3.279 2.22 5-

JS1f

1.07 1.49 1.58 2.00 8.79 0.73

FSR 102 – MP 2.645

DSR 2018-1.3

STA 23+15.25

Hydraulics Report FSR 102 – MP 2.645

WV ERFO FS MNGAH921 2018-1(1) DSR 2018-1.3 – STA 23+15.25

1. Purpose The purpose of this report is to confirm the proposed pipe size at FSR 102 - MP 2.645 (DSR 2018-1.3 – STA 23+15.25) will meet capacity requirements.

2. Background / Assessment The 2018-1.3 culvert site is located on Public Road 102, about 0.40 miles south of the intersection with Lost Run. A visual assessment was performed at Site FSR 102 DSR 2018-1.3 in December 2021 by performed by the U.S. Forest Service personnel (Forest Service). The existing culvert that crosses Public Road 102 is an 18” CMP that crosses beneath the gravel roadway. Water flows down a roadside swale toward the pipe which outlets directly into Cranberry River, a stream that runs parallel to the road. Figure 1 shows the conditions of the road and embankment near the location of the culvert and the Cranberry River, at the downstream end of the culvert. The repairs for this site include embankment repairs with riprap and geotextile lining, roadway reconditioning, aggregate surface, remove and replace existing cross pipe, ditch reconditioning and shoulder reconstruction. To support the proposed design, a hydraulic HY-8 model was run to confirm the proposed size of the replacement culvert, and a Hydraulic Toolbox model was run to confirm any outfall protection needed on the downstream end of the culvert which discharges to the Cranberry River.

The FSR 102 DSR 2018-1.3 is located within Pocahontas County and has a drainage area of 4.55 acres.

Peak discharges at the project location were calculated using the Rational method. The Rational method is the selected method for estimating peak discharges of drainage areas less than 200 acres. Calculation is based on a simple formula: = , where Q (cfs) is the peak discharges, C is the runoff coefficient, i (in/hr) is the design rainfall intensity, and A (acres) is the drainage area.

Runoff coefficients for various types of land use, hydrologic soil groups and land slopes are provided by West Virginia DOT Drainage Manual. Time of concentration and the drainage area were manually delineated in ESRI GIS using County LIDAR contours and Survey data.

Table 1: Summary of Hydrologic Analysis

4.55 0.35 23.37

Rainfall intensity was read from the NOAA Atlas 14 point precipitation frequency estimates data center with an intensity duration determined based upon the time of concentration.

Peak discharges results are shown in Table 2.

Table 2: Peak Discharge Results Return Period (year) 25

Peak Discharges (cfs) 6.0

According to Chapter 7 of the PDDM, the design flood standards for culverts are based on roadway classification. This roadway is considered a Low-Standard Road. Cross culverts for this classification are required to convey runoff from the 25-year flood.

4. Hydraulic Modeling The Federal Highway Administrations (FHWA) HY-8 program was used for hydraulic modeling and analysis of the culvert replacement.

4.1. Proposed Conditions

As the length and inverts of the replacement culvert will be adjusted based on field conditions, the purpose of this hydraulic analysis is to confirm the slope and pipe size that will convey the 25-year discharge while meeting PDDM standards.

Tailwater conditions were input based on proposed downstream conditions. The riprap will be placed with a slope of 2H:1V. A trapezoidal channel was input with bottom width of 10-feet and side slopes of 5:1 to approximate the conditions of discharge to an open slope. A manning’s n value of 0.055 was assigned to this downstream area.

The culvert data was assigned as a 30” x 19” Elliptical Reinforced Concrete Pipe with manning’ n of 0.012.

The culvert type was set to “Straight”, inlet configuration was set to “Grooved Edge Projecting” and no inlet depression was assigned. Pipe length was input as 22 feet with upstream invert 3282.36, downstream invert 3281.91 with a pipe slope of 2.0%.

The analysis of the 30” x 19” pipe showed that the culvert can convey the 25-YR design flow, with a headwater elevation of 3283.35, or a depth of 0.99 feet, this results in a headwater to depth ratio of 0.99’/1.58’ = 0.63, satisfying PDDM criteria for a HW/D value less than 1.5 for pipes 48” or less.

The proposed roadway crest elevation is 3286.41 feet, and the bottom of aggregate base layer is proposed as 3285.91. The headwater WSEL is less than the bottom of the aggregate base layer, meeting PDDM

Figure 4: HY-8 Analysis – 30 x 19 RCP at 2.0% Slope

5. Outlet Protection Riprap should be placed at the culvert outlet in accordance with EFLHD detail E251-01 with slope set to match the existing grade.

6. Design Recommendations At MP 2.645, a 30” x 19” Elliptical Reinforced Concrete Pipe is recommended with a minimum slope of 2.0%. It is recommended that riprap be placed at the culvert outlet in accordance with EFLHD detail E251-

23+15.25 20+11.41

Source: Esri, Maxar, Earthstar 0 180 360 540 72090

Feet μ

Legend Drainage Area

SHEET FLOW

SHALLOW CONC. FLOW

Date:

Sheet Flow:

Reference Units

Surface Description Woods: Light underbrush Total

Manning's 'n' n HEC-22 Table 4.2 0.400 Flow Length ( 100 ft) L (ft) 100.00

2-Yr, 24-Hr Rainfall

P2

NOAA Atlas 14 Locally determined depth

(in) 2.76

Upstream elevation E1 (ft) 3840.50 Downstream elevation E2 (ft) 3836.80 Land slope S (E1-E2)/L (ft/ft) 0.037 Travel time - Sheetflow TSH HEC-22 Eqn 4.3 (min) 18.08 18.08

Reference Units

Surface Description

Unpaved (shallow concentrate d flow)

Intercept Coefficient, k HEC-22 Table 4.3 0.49 Flow Length L (ft) 1774.00 Upstream elevation E1 (ft) 3836.80 Downstream elevation E2 (ft) 3287.00 Watercourse Slope (0.005 ft/ft min.) S (E1-E2)/L % 31%

Average Velocity V HEC-22 Eqn 4.4 (ft/s) 8.966

Travel Time TSC HEC-22 Eqn 4.6 (min) 3.30 3.30

Channel Flow:

Reference Units

Channel Shape Triangular Flow Depth or Pipe Diameter D (ft) 1.0 Channel Top Width WT (ft) 3.0

Average Channel Side Slope Z:1 Trapezoidal Channel only

Approximate Channel Bottom WB

Trapezoidal Channel only (ft) 0.0

Cross Sectional Flow Area A (ft) 1.5

Wetted Perimeter Pw (ft) 3.6 Hydraulic Radius R A/PW (ft) 0.4 Upstream elevation E1 (ft) 3287.00 Downstream elevation E2 (ft) 3282.14 Channel Slope, s S (E1-E2)/L (ft/ft) 0.025

Channel Material

Ditch - Brush/Unmai ntained Manning's 'n' n 0.080 Velocity V HEC-22 Eqn 4.5 (ft/s) 1.634 Flow Length L (ft) 196.00 Travel time TCH HEC-22 Eqn 4.6 (min) 2.00 2.0

Watershed Time of Concentration or Travel Time (min) = 23.37

Compute Time of Concentration (Tc) or Travel Time (Tt)

Shallow Concentrated Flow:

Time of Concentration Worksheet

MNGHA LL

2018-1.3 STA 23+15.25 WSP

Data type: Precipitation intensity Time series type: Partial duration Project area: Ohio River Basin Location na West Virgi USA Station Name: - Latitude: 38.2381 Degree Longitude: -80.3072 Degree Elevation (USGS): 3281 ft

PRECIPITATION FREQUENCY ESTIMATES

by duration 1 2 5 10 25 50 100 200 500 1000 5-min: 3.61 4.33 5.16 5.77 6.53 7.04 7.55 8.02 8.58 9 5 10-min: 2.89 3.46 4.14 4.61 5.18 5.59 5.98 6.34 6.76 7.06 10 15-min: 2.4 2.9 3.48 3.88 4.38 4.72 5.03 5.32 5.67 5.9 15 30-min: 1.65 2 2.47 2.81 3.23 3.54 3.84 4.13 4.5 4.76 30 60-min: 1.02 1.25 1.58 1.83 2.15 2.4 2.64 2.89 3.22 3.47 60 2-hr: 0.631 0.774 0.972 1.12 1.32 1.48 1.64 1.81 2.03 2.22 120 3-hr: 0.456 0.557 0.697 0.803 0.949 1.06 1.19 1.31 1.48 1.63 180 6-hr: 0.279 0.337 0.418 0.481 0.571 0.644 0.722 0.804 0.921 1.02 12-hr: 0.168 0.201 0.248 0.287 0.343 0.39 0.441 0.496 0.576 0.645 24-hr: 0.097 0.116 0.139 0.159 0.186 0.207 0.23 0.253 0.292 0.327 2-day: 0.059 0.069 0.083 0.094 0.108 0.12 0.132 0.144 0.161 0.174 3-day: 0.043 0.051 0.06 0.068 0.078 0.086 0.094 0.102 0.113 0.122 4-day: 0.035 0.042 0.049 0.055 0.063 0.069 0.075 0.081 0.09 0.096 7-day: 0.025 0.03 0.035 0.039 0.044 0.048 0.052 0.055 0.061 0.065 10-day: 0.021 0.024 0.028 0.031 0.035 0.038 0.041 0.044 0.048 0.051 20-day: 0.015 0.017 0.02 0.022 0.024 0.026 0.028 0.03 0.032 0.034 30-day: 0.013 0.015 0.017 0.018 0.02 0.022 0.023 0.024 0.026 0.027 45-day: 0.011 0.013 0.014 0.016 0.017 0.018 0.019 0.02 0.022 0.023 60-day: 0.01 0.012 0.013 0.014 0.015 0.016 0.017 0.018 0.019 0.019

Date/time (GMT): Thu Jul 17 19:55:05 2025 pyRunTime: 0.0077021121978759766

Date:

4.55 0.35

23.37

2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 200-yr 500-yr

2.40 2.92 3.28 3.74 4.06 4.37 4.66 5.02

2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 200-yr 500-yr

3.8 4.6 5.2 6.0 6.5 7.0 7.4 8.0

Interpolated Rainfall Intensity, I (in/hr)

Peak Flow, Q (cfs)

Forested C/D Soils

Notes

Computed Tc (min) See Tc Worksheet

Compute Peak Flow Rates

Rational Method Worksheet

Area (ac) Runoff Coefficient

MNGHA

2018-1.3 STA 23+15.25

LL

WSP

Crossing Name

Culvert Name

Total Discharge (cfs)

Culvert Discharge (cfs)

Headwater Elevation (ft)

Inlet Control Depth (ft)

Outlet Control Depth (ft)

HW / D

(ft)

Normal Depth (ft)

Critical Depth (ft)

Outlet Depth (ft)

Outlet Velocity (ft/s)

2018-1.3 23+15.25 100%

Culvert

6.00 6.00 3283.35 0.99 0.349 0.62 0.45 0.71 0.49 6.81

Crossing Input: 2018-1.3 23+15.25 100%

DISCHARGE DATA

Discharge Method Minimum, Design, and

Maximum Minimum Flow 1.000 cfs Design Flow 6.000 cfs Maximum Flow 7.000 cfs

TAILWATER DATA

Channel Type Trapezoidal Channel Bottom Width 10.000 ft Side Slope (H:V) 5.000 _:1 Channel Slope 0.5000 ft/ft Manning's n (channel) 0.055 Channel Invert Elevation 3281.920 ft Rating Curve View...

ROADWAY DATA

Roadway Profile Shape Constant Roadway

Elevation First Roadway Station 0.000 ft Crest Length 100.000 ft Crest Elevation 3286.410 ft Roadway Surface Gravel Top Width 12.000 ft

Culvert Input: 2018-1.3 23+15.25 100% Parameter Value Units

CULVERT DATA

Name Culvert 1 Shape Elliptical Material Concrete Size Define...

Span 30.000 in Rise 19.000 in Embedment Depth 0.000 in Manning's n 0.012 Culvert Type Straight Inlet Configuration Grooved Edge Projecting

(Ke=0.2) Inlet Depression? No

SITE DATA

Site Data Input Option Culvert Invert Data Inlet Station 0.000 ft Inlet Elevation 3282.360 ft Outlet Station 22.000 ft Outlet Elevation 3281.920 ft

Discharge (cfs)

Culvert Discharge (cfs)

Headwater Elevation (ft)

Inlet Control Depth (ft)

Outlet Control Depth (ft)

HW

/ D (ft)

Flow Type

Normal Depth (ft)

Critical Depth (ft)

Outlet Depth (ft)

Tailwater Depth (ft)

Outlet Velocity (ft/s)

Tailwater Velocity (ft/s)

1.00 1.00 3282.72 0.36 0.0* 0.23 1-S2n 0.19 0.28 0.19 0.04 4.28 2.30

1.60 1.60 3282.82 0.46 0.0* 0.29 1-S2n 0.24 0.35 0.24 0.06 4.90 2.76

2.20 2.20 3282.90 0.54 0.0* 0.34 1-S2n 0.27 0.42 0.28 0.07 5.35 3.12

2.80 2.80 3282.98 0.62 0.051 0.39 1-S2n 0.31 0.47 0.32 0.08 5.68 3.42

3.40 3.40 3283.04 0.68 0.110 0.43 1-S2n 0.34 0.52 0.36 0.09 5.97 3.68

4.00 4.00 3283.11 0.75 0.167 0.47 1-S2n 0.37 0.57 0.39 0.10 6.20 3.92

4.60 4.60 3283.17 0.81 0.222 0.51 1-S2n 0.39 0.62 0.43 0.11 6.41 4.13

5.20 5.20 3283.25 0.89 0.277 0.56 1-S2n 0.42 0.66 0.46 0.11 6.59 4.33

6.00 6.00 3283.35 0.99 0.349 0.62 1-S2n 0.45 0.71 0.49 0.12 6.81 4.56

6.40 6.40 3283.39 1.03 0.385 0.65 1-S2n 0.46 0.74 0.51 0.13 6.92 4.67

7.00 7.00 3283.45 1.09 0.439 0.69 1-S2n 0.48 0.77 0.54 0.14 7.06 4.83

31.82 31.10 3286.43 4.07 3.179 2.57 5-S2n 1.15 1.45 1.32 0.33 10.95 8.31

FSR 102 – MP 4.144

DSR 2018-1.4

STA 16+89.52

Hydraulics Report FSR 102 – MP 4.144

WV ERFO FS MNGAH921 2018-1(1) DSR 2018-1.4 - STA 16+89.52

1. Purpose The purpose of this report is to confirm the proposed pipe size at FSR 102 - MP 4.144 (DSR 2018-1.4 – STA 16+89.52) will meet capacity requirements.

2. Background / Assessment The 2018-1.4 culvert site is located on Public Road 102, about 0.2 miles south of the intersection with Forks of Cranberry Trail (at project STA 16+89.5). This culvert was identified as 2018-1.1 in the 70% submittal.

A visual assessment was performed at Site FSR 102 DSR 2018-1.4 in December 2021 by the U.S. Forest Service personnel (Forest Service). The existing culvert that crosses Public Road 102 is an 18” CMP that crosses beneath the gravel roadway. Water flows down a roadside swale toward the pipe which outlets directly into Cranberry River, a stream that runs parallel to the road. Figure 1 shows the conditions of the road and embankment near the location of the culvert and the Cranberry River, at the downstream end of the culvert. The repairs for this site include roadway reconditioning, remove and replace the existing cross pipe and ditch reconditioning. To support the proposed design, a hydraulic HY-8 model was run to confirm the proposed size of the replacement culvert.

The FSR 102 DSR 2018-1.4 is located within Pocahontas County and has a drainage area of 39.7 acres.

Peak discharges at the project location were calculated using the Rational method. The Rational method is the selected method for estimating peak discharges of drainage areas less than 200 acres. Calculation is based on a simple formula: = , where Q (cfs) is the peak discharges, C is the runoff coefficient, i (in/hr) is the design rainfall intensity, and A (acres) is the drainage area.

Runoff coefficients for various types of land use, hydrologic soil groups and land slopes are provided by West Virginia DOT Drainage Manual. Time of concentration and the drainage area were manually delineated in ESRI GIS using County LIDAR contours and Survey data.

Table 1: Summary of Hydrologic Analysis

Drainage Area (Ac) Runoff Coefficient (C) Tc (min)

39.7 0.25 32.8

Rainfall intensity was read from the NOAA Atlas 14 point precipitation frequency estimates data center

Peak discharges results are shown in Table 2.

Table 2: Peak Discharge Results

Return Period (year) 25 Peak Discharges (cfs) 31.2

According to Chapter 7 of the PDDM, the design flood standards for culverts are based on roadway classification. This roadway is considered a Low-Standard Road. Cross culverts for this classification are required to convey runoff from the 25-year flood.

Hydraulic Modeling The Federal Highway Administrations (FHWA) HY-8 program was used for hydraulic modeling and analysis of the culvert replacement.

3.1. Proposed Conditions

As the length and inverts of the replacement culvert will be adjusted based on field conditions, the purpose of this hydraulic analysis is to confirm the slope and pipe size that will convey the 25-year discharge while meeting PDDM standards.

Tailwater conditions were input based on proposed downstream conditions. Riprap will be placed with a slope of approximately 0.5%. A trapezoidal channel was input with bottom width of 10-feet and side slopes of 5:1 to approximate the conditions of discharge to an open slope. A manning’s n value of 0.055 was assigned to this downstream area.

The culvert data was assigned as a 42” x 27” Elliptical Reinforced Concrete Pipe with manning’ n of 0.012.

The culvert type was set to “Straight”, inlet configuration was set to “Grooved Edge Projecting” and no inlet depression was assigned. Pipe length was input as 30 feet with upstream invert 3183.90, downstream invert 3182.96 with a pipe slope of 2.0%.

The analysis of the 42” x 27” pipe showed that the culvert would backwater under the 25-YR design flow, with a headwater elevation of 3186.20, or a depth of 2.3 feet. Applying a rise of 27-inches (2.24-feet) this results in a headwater to depth ratio of 2.3’/2.25’ = 1.02, satisfying PDDM criteria for a HW/D value less than 1.5 for pipes 48” or less.

The proposed roadway crest elevation is 3187.62 feet, and bottom of aggregate base layer is proposed as

3187.12. The headwater WSEL is less than the bottom of the aggregate base layer, meeting PDDM

Figure 4: HY-8 Analysis – 42 x 27 RCP at 2.0% Slope

Outlet Protection Riprap should be placed at the culvert outlet in accordance with EFLHD detail E251-01 with slope set to match the existing grade.

Design Recommendations At MP 4.144, a 42” x 27” Elliptical Reinforced Concrete Pipe is recommended with a minimum slope of 2.0%. It is recommended that riprap be placed at the culvert outlet in accordance with EFLHD detail E251-

20+28.55

10+29.14

Source: Esri, Maxar, Earthstar Geographics, and the GIS User Community 0 450 900 1,350 1,800225

Feet μ

Legend Drainage Area

SHEET FLOW

SHALLOW CONC. FLOW

Date:

Sheet Flow:

Reference Units

Surface Description Woods: Light underbrush Total

Manning's 'n' n HEC-22 Table 4.2 0.400 Flow Length ( 100 ft) L (ft) 100.00

2-Yr, 24-Hr Rainfall

P2

NOAA Atlas 14 Locally determined depth

(in) 2.76

Upstream elevation E1 (ft) 4068.00 Downstream elevation E2 (ft) 4066.00 Land slope S (E1-E2)/L (ft/ft) 0.020 Travel time - Sheetflow TSH HEC-22 Eqn 4.3 (min) 23.12 23.12

Reference Units

Surface Description

Unpaved (shallow concentrate d flow)

Intercept Coefficient, k HEC-22 Table 4.3 0.49 Flow Length L (ft) 4257.10 Upstream elevation E1 (ft) 4066.00 Downstream elevation E2 (ft) 3183.90 Watercourse Slope (0.005 ft/ft min.) S (E1-E2)/L % 21%

Average Velocity V HEC-22 Eqn 4.4 (ft/s) 7.331

Travel Time TSC HEC-22 Eqn 4.6 (min) 9.68 9.68

Channel Flow:

Reference Units

Channel Shape Triangular Flow Depth or Pipe Diameter D (ft) Channel Top Width WT (ft) 3.0

Average Channel Side Slope Z:1 Trapezoidal Channel only

Approximate Channel Bottom WB

Trapezoidal Channel only (ft) 0.0

Cross Sectional Flow Area A (ft) Wetted Perimeter Pw (ft) Hydraulic Radius R A/PW (ft) Upstream elevation E1 (ft) Downstream elevation E2 (ft) Channel Slope, s S (E1-E2)/L (ft/ft)

Channel Material

Ditch - Brush/Unmai ntained…