Umpqu615-2022-2(1) Hydraulics Report.pdf

Memorandum

Western Federal Lands Highway Division 610 E. Fifth Street

Vancouver, WA 98661-3801

HYDRAULIC ANALYSIS AND RECOMMEDATIONS FOR CULVERTS

REPLACEMNT

Date: April 8, 2024

Revised May 7, 2024

To: Carrie Warren, WFLHD Project Manager

From: Degefu Sebro, WFLHD Hydraulics Engineer

Project: OR ERFO FS Umpqu615-2022-2(1) - 4711-1.70

Background

A high flow event occurred due to a rain on snow and damaged sections of FS-4711 Road in the

Umpqua National Forest, in Douglas County, Oregon. Approximately 120’ of the road was partially washed out by reducing its width by 4.5' at the narrowest. There are two 18" diameter Corrugated

Metal Pipes (CMPs) at the southern and northern edges of the failure site. According to DDIR, piping appears to have been occurring under the southern edge pipe. Western Federal Lands

Highway Division (WFLHD) is completing the designs for the proposed improvements. The purpose of this report is twofold: (1) to propose replacements for one of the 18” CMP at south by assessing the hydraulic capacity of the existing pipe and the installation of a new pipe that considers factors such as debris flow and resilience, and (2) to recommend the riprap size for the in-kind replacement of the outlet protection of the northern edge 18” CMP. See Vicinity and Location Maps in Figure 1 and 2.

Existing Site Condition

Heavy storm induced failures of USFS forest roads occurred in the Umpqua National Forest in 2022.

Debris flows have been observed at two closely situated locations, both originating from the slope of the road fill. The roadway damage at FS4711-1.70 occurred due to a rain on snow weather event that caused debris flow. At the project location, a stream crossing is situated at the southern boundary, facilitated by 18-inch CMP. There is a ditch culvert of 18” at the northern edge. See Figure

3. Per the finding outlined in the DDIR, indications of piping activity underneath the southern edge

Memo to: Carrie Warren, WFLHD Project Manager

May 7, 2024 culvert have been observed. Considering this assessment, the road repairs include the replacement of the existing 18-inch CMP pipes.

Hydraulic Analysis and Methodology

Peak Discharges

Flood frequency discharges at this location were estimated using the rational equation as the size of the watershed of the stream crossings was below the threshold for the regression equations used by

USGS StreamStats to estimate peak annual discharge (see Figure 4 for rational equation calculations and peak flow estimation). The drainage area was delineated manually using ArcGIS Pro and USGS

National base maps as a reference (Figure 3). The southern edge pipe has a drainage area of 35 acre and the northern edge location has 20 acres. The rainfall intensity data was retrieved from NOAA-

Atlas2 Volume 9 for the specific project location (Reference 3). Due to the limitation of rainfall intensity data at the project site, peak discharges were calculated for the 2- and 100-year storm events only. But various probability distribution fitting methods could be used to estimate discharges for the corresponding intermediate return periods. However, with only two discharge data points (2-yr and 100-yr discharges), fitting a distribution accurately may not be feasible. More data points would be needed for more reliable estimation. The estimated peak flows were multiplied by a bulking factor to accommodate potential debris and sediment load. The estimated peak flows at this location are 2 and 7 cfs, for 2- and 100-yr events, respectively. See Figure 4.

The northern edge 18” CMP location is approximately 264 ft away from the southern edge CMP and will be replaced in-kind. The peak flows calculated at this location were used for riprap sizing.

The estimated discharges at this location are 2 and 4 cfs, for 2- and 100-yr discharges, respectively

See Figure 5.

Hydraulics Modeling

Hydraulic analysis of the southern edge culvert indicates that the 100-yr water surface elevation is above the crown of the 18” CMP at the existing condition. Upgrading to a 36-inch culvert considering the existing site conditions and available roadway cover will have an additional 1.76 feet of freeboard. Climate change predictions combined with the reduction of forest cover in the watershed suggest that larger stream flows and increased debris will become more common. The larger culvert will provide resilience to climate change and expected sediment transport by providing an additional 1.76 feet of freeboard compared to the exiting 18-inch culvert. Based on HY-8 and field survey data, it should be possible to install the larger culvert without raising the current road elevation. See Appendix A- HY-Report for Existing Southern Edge CMP and Appendix B- HY-

Report for Proposed Southern Edge CMP.

The hydraulics analysis results for the northern edge 18” CMP pipe are summarized in Appendix C and used for riprap sizing. The riprap size calculations are presented in Figure 6.

Memo to: Carrie Warren, WFLHD Project Manager

May 7, 2024

Recommendations:

Southern Edge 18” CMP

• Remove existing 18-inch culvert.

• Install a 36-inch round CMP to pass the 100-year peak flow and expected debris o Set culvert to match upstream and downstream slopes o Set length according to roadway width and embankment slope requirements.

Northern Edge 18” CMP

• Remove existing 18-inch culvert.

• Install new 18”-inch round CMP.

o Set culvert to match upstream and downstream slopes.

o Set length according to roadway width and embankment slope requirements.

• Install class 3 riprap, method B, minimum 3’ thickness.

• Use geotextile, class 2, type A.

Attachments: Figure 1. Location Map

Figure 2. Vicinity Map

Figure 3. Drainage Area Map

Figure 4. Hydrology-Summary of Peak Flows for Southern Edge CMP.

Figure 5. Hydrology-Summary of Peak Flows for Northern Edge CMP.

Figure 6. Riprap Size calculations

Appendix A- HY-8 Report for Existing Southern Edge CMP

Appendix B- HY-8 Report for Proposed Southern Edge CMP

Appendix C- HY-8 Report for Northern Edge CMP

References

Project Location

USGS The National Map: National Boundaries Dataset, 3DEP Elevation Program, Geographic Names Information System, National Hydrography Dataset, National Land Cover Database, National Structures Dataset, and National Transportation Dataset; USGS Global Ecosystems; U.S. Census Bureau TIGER/Line data; USFS Road Data; Natural Earth Data; U.S.

Department of State Humanitarian Information Unit; and NOAA National Centers for Environmental Information, U.S. Coastal Relief Model. Data refreshed April, 2023.

¹

Figure 1 OR_ERFO_FS_Umpqu615-2022-2(1) Location Map

Umpqua NF D Road 4711 Crossing

0 25 5012.5 Miles

Project Location

USGS The National Map: National Boundaries Dataset, 3DEP Elevation Program, Geographic Names Information System, National Hydrography Dataset, National Land Cover Database, National Structures Dataset, and National Transportation Dataset; USGS Global Ecosystems; U.S. Census Bureau TIGER/Line data; USFS Road Data; Natural Earth Data; U.S.

Department of State Humanitarian Information Unit; and NOAA National Centers for Environmental Information, U.S. Coastal Relief Model. Data refreshed April, 2023.

¹

Figure 2 Vicinity Map OR_ERFO_FS_Umpqu615-2022-2(1)

Umpqua NF D Road 4711 Crossing

0 0.5 10.25 Miles

DA= 20 acre

DA= 35 acre

USGS The National Map: National Boundaries Dataset, 3DEP Elevation Program, Geographic Names Information System, National Hydrography Dataset, National Land Cover Database, National Structures Dataset, and

National Transportation Dataset; USGS Global Ecosystems; U.S. Census Bureau TIGER/Line data; USFS Road data; Natural Earth Data; U.S. Department of State

HIU; NOAA National Centers for Environmental Information

Figure 3

OR_ERFO_FS_Umpqu615-2022-2(1)

36" CMP _Southern Edge

18" CMP_Northern Edge

Drainage Area of 18"

CMP

Drainage Area of 36"

CMP

0 1,000 2,000500

Feet

Southern Edge CMP

Northern Edge CMP

Peak Discharge Calculations Southern Edge CMP

The Rational Method (or Rational Formula) is:

Q = C i A

Where:

Q = Peak flow in cubic feet per second (cfs)

C = Runoff coefficient to reflect the ratio of rainfall to surface runoff i = Rainfall intensity in inches per hour (in/hr)

A = Drainage area in acres (acre)

• The NF47-4711-1.7 site Drainage area was manually delineated using ArcGIS and USGS topographic maps. The Total Drainage area is approximately 49 acres.

• The Rainfall intensity was obtained from NOAA-Atlas (Refence 3).

• Runoff coefficient was used from ODOT-Hydraulics Manual (0.2) (Reference 4) i2 0.23 6-hr Duration(in/hr) i100 0.47 6-hr Duration (in/hr)

A 35 Acre

C 0.2

Recurrence Interval (Years)

2-Yr 100-Yr

Peak Discharge

(cfs)

1.6 3.3

*Peak Discharge

(cfs)

3 7

FIGURE 4

Hydrology for Southern Edge CMP

OR_ERFO_FS_Umpqu615-2022-2(1)

Peak Discharge Calculations for Northern Edge CMP

The Rational Method (or Rational Formula) is:

Q = C* i *A

Where:

Q = Peak flow in cubic feet per second (cfs)

C = Runoff coefficient to reflect the ratio of rainfall to surface runoff i = Rainfall intensity in inches per hour (in/hr)

A = Drainage area in acres (acre)

• The NF47-4711-1.7 site Drainage area was manually delineated using ArcGIS and USGS topographic maps. The Total Drainage area is approximately 20 acres.

• The Rainfall intensity was obtained from NOAA-Atlas (Refence 3).

• Runoff coefficient was used from ODOT-Hydraulics Manual (0.2) (Reference 4)

* Bulking Factor of 2 applied i2 0.23 6-hr Duration(in/hr) i100 0.47 6-hr Duration (in/hr)

A 20 Acre

C 0.2

Recurrence Interval (Years)

2-Yr 100-Yr

Peak Discharge

(cfs)

1 1.9

*Peak Discharge

(cfs)

2 4

FIGURE 5

Hydrology for Northern Edge CMP

Riprap Size and Apron Design for Northern Edge CMP

The riprap size was calculated using the HEC-14 Manual guideline for the Circular culverts:

D50= 0.2 D ( 𝑄

√𝑔 𝐷2.5

) (4/3) ( 𝐷

𝑇𝑊

), Equation (10.4), HEC-14, pp.10-17

Based on the Hydraulic analysis result from HY-8 model, The CMP#2 culvert flows under a supercritical condition (Yc= 0.77 ft and Yn= 0.3).

For this condition, an adjusted Culvert rise can be calculated using D’ = ( 𝐷+𝑌𝑛

); Equation (10.5), HEC-14, pp.10-17.

Using the CMP diameter of D= 1.5 ft and Yn= 0.3 ft, the value of D’= 0.9 ft

Therefore D50= 0.606 ft = 7.27 inches.

Based on the HEC-14 manual recommendation, D50= 7.71 inches represent a Riprap class 3.

Use riprap class 3, method B end treatment.

The Apron Length of 5D and Apron depth of 2.4 D50 is recommended. The Apron dimensions should conform to the dimensions of the outlet channel.

FIGURE 6

Riprap Size Design

Appendix A- HY-Report for Existing Southern Edge CMP

HY-8 Culvert Analysis Summary Report for Existing

Crossing Discharge Data

Discharge Selection Method: User Defined

Table 1 - Summary of Culvert Flows at Crossing: Existing (18 " CMP)

Headwater Elevation (ft)

Total Discharge (cfs)

18" CMP

Discharge (cfs)

Roadway Discharge (cfs)

Iterations

1571.66 2.00 2.00 0.00 1

1572.67 7.00 7.00 0.00 1

1574.00 11.33 11.33 0.00 Overtopping

Rating Curve Plot for Crossing: Existing (18 " CMP)

Culvert Data: 18" CMP

Table 1 - Culvert Summary Table: 18" CMP

Total Disch

Culve rt

Head water

Inle t

Outl et

Fl ow

Nor mal

Criti cal

Out let

Tailw ater

Outl et

Tailw ater arge (cfs)

Disch arge (cfs)

Elevat ion (ft)

Cont rol Dep th (ft)

Cont rol Dep th (ft)

Ty pe

Dep th (ft)

Dep th (ft)

De pth (ft)

Dept h (ft)

Velo city (ft/s

Veloc ity (ft/s)

2.00 cfs

2.00 cfs

1571.6

0.69 0.0* 1- S2 n

0.29 0.53 0.2

0.27 8.15 2.75

7.00 cfs

7.00 cfs

1572.6

1.70 0.0* 5- S2 n

0.56 1.02 0.5

0.44 11.6

3.72

* Full Flow Headwater elevation is below inlet invert.

Culvert Barrel Data

Culvert Barrel Type Straight Culvert

Inlet Elevation (invert): 1570.97 ft, Outlet Elevation (invert): 1564.80 ft

Culvert Length: 36.52 ft, Culvert Slope: 0.1714

Culvert Performance Curve Plot: 18" CMP

Water Surface Profile Plot for Culvert: 18" CMP

Site Data - 18" CMP

Site Data Option: Culvert Invert Data

Inlet Station: 0.00 ft

Inlet Elevation: 1570.97 ft

Outlet Station: 36.00 ft

Outlet Elevation: 1564.80 ft

Number of Barrels: 1

Culvert Data Summary - 18" CMP

Barrel Shape: Circular

Barrel Diameter: 1.50 ft

Barrel Material: Corrugated Steel

Embedment: 0.00 in

Barrel Manning's n: 0.0240

Culvert Type: Straight

Inlet Configuration: Thin Edge Projecting (Ke=0.9)

Inlet Depression: None

Tailwater Data for Crossing: Existing (18 " CMP)

Table 2 - Downstream Channel Rating Curve (Crossing: Existing (18 " CMP))

Flow (cfs) Water Surface Elev (ft)

Velocity (ft/s)

Depth (ft) Shear (psf) Froude Number

2.00 1551.76 0.27 2.75 2.90 1.32

7.00 1551.93 0.44 3.72 4.64 1.41

Tailwater Channel Data - Existing (18 " CMP)

Tailwater Channel Option: Irregular Channel

Channel Slope: Irregular Channel

User Defined Channel Cross-Section

Coord No. Station (ft) Elevation (ft) Manning's n

1 0.00 1581.99 0.1000 2 0.14 1581.98 0.1000 3 3.55 1581.49 0.1000 4 5.53 1581.00 0.1000 5 6.86 1580.68 0.1000 6 8.42 1580.00 0.1000 7 8.86 1579.82 0.1000 8 11.99 1579.00 0.1000 9 14.78 1578.32 0.1000 10 15.96 1578.00 0.1000 11 17.55 1577.58 0.1000 12 19.03 1577.00 0.1000 13 20.63 1576.38 0.1000 14 22.98 1576.01 0.1000 15 23.05 1575.98 0.1000 16 25.82 1575.00 0.1000 17 27.40 1574.42 0.1000 18 28.45 1574.00 0.1000 19 30.91 1573.00 0.1000 20 31.50 1572.76 0.1000 21 34.53 1572.00 0.1000 22 35.81 1571.62 0.1000 23 37.67 1571.00 0.1000 24 40.61 1570.00 0.1000 25 40.67 1569.98 0.0500 26 41.97 1569.63 0.0500 27 44.72 1569.06 0.0500

28 45.02 1569.00 0.0500 29 49.06 1568.15 0.0500 30 50.66 1568.09 0.0500 31 56.48 1568.00 0.0500 32 56.76 1567.96 0.0500 33 58.36 1567.53 0.0500 34 63.15 1567.80 0.0350 35 65.36 1567.00 0.0350 36 67.81 1566.00 0.0350 37 68.07 1565.88 0.0350 38 68.82 1565.62 0.0350 39 73.38 1565.00 0.0350 40 76.52 1564.52 0.0350 41 76.75 1564.48 0.0350 42 76.92 1564.43 0.0350 43 77.58 1564.03 0.0350 44 77.62 1564.00 0.0350 45 79.02 1563.00 0.0350 46 80.42 1562.00 0.0350 47 81.82 1561.00 0.0350 48 83.22 1560.00 0.0350 49 84.50 1559.00 0.0350 50 84.93 1558.63 0.0350 51 85.77 1558.00 0.0350 52 87.10 1557.00 0.0350 53 88.43 1556.00 0.0500 54 89.64 1555.06 0.0500 55 89.71 1555.00 0.0500 56 90.79 1554.00 0.0500 57 91.86 1553.00 0.0500 58 92.10 1552.78 0.0500 59 93.42 1552.25 0.0500 60 94.82 1552.00 0.0500 61 99.18 1551.55 0.0500 62 99.70 1551.49 0.0500 63 99.89 1551.51 0.0750 64 104.92 1552.00 0.0750 65 105.89 1552.10 0.0750 66 111.19 1552.43 0.0750 67 113.29 1552.65 0.0750 68 115.47 1552.82 0.0750 69 116.61 1553.00 0.0750 70 120.75 1553.64 0.0750 71 121.75 1554.00 0.0750 72 124.04 1554.82 0.0750 73 124.53 1555.00 0.0750 74 127.20 1556.00 0.0750 75 127.82 1556.23 0.1000 76 130.08 1557.00 0.1000 77 130.13 1557.02 0.1000

78 134.16 1558.00 0.1000 79 135.39 1558.30 0.1000 80 137.28 1558.34 0.1000 81 141.45 1558.10 0.1000 82 143.01 1558.31 0.1000 83 145.29 1558.32 0.1000 84 147.32 1559.00 0.1000 85 150.31 1560.00 0.1000 86 152.82 1560.84 0.1000 87 153.29 1561.05 0.1000 88 153.84 1561.29 0.1000 89 154.31 1561.51 0.1000 90 154.92 1562.00 0.0000

Roadway Data for Crossing: Existing (18 " CMP)

Roadway Profile Shape: Constant Roadway Elevation

Crest Length: 200.00 ft

Crest Elevation: 1574.00 ft

Roadway Surface: Paved

Roadway Top Width: 19.00 ft

Appendix B- HY-Report for Proposed Southern Edge CMP

HY-8 Culvert Analysis Summary Report for Proposed

Crossing Discharge Data

Discharge Selection Method: User Defined

Table 1 - Summary of Culvert Flows at Crossing: Proposed (36" CMP)

Headwater Elevation (ft)

Discharge Names

Total Discharge (cfs)

36" CMP

Discharge (cfs)

Roadway Discharge (cfs)

Iterations

1571.58 2-yr 2.00 2.00 0.00 1

1572.21 25-yr 7.00 7.00 0.00 1

1574.00 Overtopping 19.00 19.00 0.00 Overtopping

Rating Curve Plot for Crossing: Proposed (36" CMP)

Culvert Data: 36" CMP

Table 1 - Culvert Summary Table: 36" CMP

Disc harg

Total Disc

Culv ert

Head water

Inle t

Out let

Fl o

Nor mal

Crit ical

Ou tle

Tail wate

Outl et

Tail wate e Nam es harg e (cfs)

Disc harg e (cfs)

Eleva tion (ft)

Con trol Dep th (ft)

Con trol Dep th (ft) w Ty pe

Dep th (ft)

De pth (ft) t De pth (ft) r Dept h (ft)

Vel ocit y (ft/ s) r Velo city (ft/s

2-yr 2.00 cfs

2.00 cfs

1571.

0.61 0.0* 1- S2 n

0.26 0.4

0.2

0.27 8.50 2.75

25-yr

7.00 cfs

7.00 cfs

1572.

1.24 0.0* 1- S2 n

0.47 0.9

0.4

0.44 12.3

3.72

* Full Flow Headwater elevation is below inlet invert.

Culvert Barrel Data

Culvert Barrel Type Straight Culvert

Inlet Elevation (invert): 1570.97 ft, Outlet Elevation (invert): 1561.50 ft

Culvert Length: 45.01 ft, Culvert Slope: 0.2152

Culvert Performance Curve Plot: 36" CMP

Water Surface Profile Plot for Culvert: 36" CMP

Site Data - 36" CMP

Inlet Station: 0.00 ft

Inlet Elevation: 1570.97 ft

Outlet Station: 44.00 ft

Outlet Elevation: 1561.50 ft

Number of Barrels: 1

Culvert Data Summary - 36" CMP

Barrel Shape: Circular

Barrel Diameter: 2.00 ft

Barrel Material: Corrugated Steel

Inlet Configuration: Thin Edge Projecting (Ke=0.9)

Inlet Depression: None

Tailwater Data for Crossing: Proposed (36" CMP)

Table 2 - Downstream Channel Rating Curve (Crossing: Proposed (36" CMP))

Flow (cfs) Water Surface Elev (ft)

Velocity (ft/s)

Depth (ft) Shear (psf) Froude Number

2.00 1551.76 0.27 2.75 2.90 1.32

7.00 1551.93 0.44 3.72 4.64 1.41

Tailwater Channel Data - Proposed (36" CMP)

Tailwater Channel Option: Irregular Channel

Channel Slope: Irregular Channel

User Defined Channel Cross-Section

Coord No. Station (ft) Elevation (ft) Manning's n

1 0.00 1581.99 0.1000 2 0.14 1581.98 0.1000 3 3.55 1581.49 0.1000 4 5.53 1581.00 0.1000 5 6.86 1580.68 0.1000 6 8.42 1580.00 0.1000 7 8.86 1579.82 0.1000 8 11.99 1579.00 0.1000 9 14.78 1578.32 0.1000 10 15.96 1578.00 0.1000 11 17.55 1577.58 0.1000 12 19.03 1577.00 0.1000 13 20.63 1576.38 0.1000 14 22.98 1576.01 0.1000 15 23.05 1575.98 0.1000 16 25.82 1575.00 0.1000 17 27.40 1574.42 0.1000 18 28.45 1574.00 0.1000 19 30.91 1573.00 0.1000 20 31.50 1572.76 0.1000 21 34.53 1572.00 0.1000 22 35.81 1571.62 0.1000 23 37.67 1571.00 0.1000 24 40.61 1570.00 0.1000 25 40.67 1569.98 0.0500 26 41.97 1569.63 0.0500 27 44.72 1569.06 0.0500

28 45.02 1569.00 0.0500 29 49.06 1568.15 0.0500 30 50.66 1568.09 0.0500 31 56.48 1568.00 0.0500 32 56.76 1567.96 0.0500 33 58.36 1567.53 0.0500 34 63.15 1567.80 0.0350 35 65.36 1567.00 0.0350 36 67.81 1566.00 0.0350 37 68.07 1565.88 0.0350 38 68.82 1565.62 0.0350 39 73.38 1565.00 0.0350 40 76.52 1564.52 0.0350 41 76.75 1564.48 0.0350 42 76.92 1564.43 0.0350 43 77.58 1564.03 0.0350 44 77.62 1564.00 0.0350 45 79.02 1563.00 0.0350 46 80.42 1562.00 0.0350 47 81.82 1561.00 0.0350 48 83.22 1560.00 0.0350 49 84.50 1559.00 0.0350 50 84.93 1558.63 0.0350 51 85.77 1558.00 0.0350 52 87.10 1557.00 0.0350 53 88.43 1556.00 0.0500 54 89.64 1555.06 0.0500 55 89.71 1555.00 0.0500 56 90.79 1554.00 0.0500 57 91.86 1553.00 0.0500 58 92.10 1552.78 0.0500 59 93.42 1552.25 0.0500 60 94.82 1552.00 0.0500 61 99.18 1551.55 0.0500 62 99.70 1551.49 0.0500 63 99.89 1551.51 0.0750 64 104.92 1552.00 0.0750 65 105.89 1552.10 0.0750 66 111.19 1552.43 0.0750 67 113.29 1552.65 0.0750 68 115.47 1552.82 0.0750 69 116.61 1553.00 0.0750 70 120.75 1553.64 0.0750 71 121.75 1554.00 0.0750 72 124.04 1554.82 0.0750 73 124.53 1555.00 0.0750 74 127.20 1556.00 0.0750 75 127.82 1556.23 0.1000 76 130.08 1557.00 0.1000 77 130.13 1557.02 0.1000

78 134.16 1558.00 0.1000 79 135.39 1558.30 0.1000 80 137.28 1558.34 0.1000 81 141.45 1558.10 0.1000 82 143.01 1558.31 0.1000 83 145.29 1558.32 0.1000 84 147.32 1559.00 0.1000 85 150.31 1560.00 0.1000 86 152.82 1560.84 0.1000 87 153.29 1561.05 0.1000 88 153.84 1561.29 0.1000 89 154.31 1561.51 0.1000 90 154.92 1562.00 0.0000

Roadway Data for Crossing: Proposed (36" CMP)

Roadway Profile Shape: Constant Roadway Elevation

Crest Length: 200.00 ft

Crest Elevation: 1574.00 ft

Appendix C- HY-Report for Northern Edge CMP

HY-8 Culvert Analysis Summary Report for Northern Edge CMP

Crossing Discharge Data

Discharge Selection Method: User Defined

Table 1 - Summary of Culvert Flows at Crossing: 18" CMP

Headwater Elevation (ft)

Total Discharge (cfs)

18" CMP-#2

Discharge (cfs)

Roadway Discharge (cfs)

Iterations

1543.43 2.00 2.00 0.00 1

1543.65 4.00 4.00 0.00 1

1550.00 19.71 19.71 0.00 Overtopping

Rating Curve Plot for Crossing: 18" CMP

Culvert Data: 18" CMP-#2

Table 1 - Culvert Summary Table: 18" CMP-#2

Total Disch

Culve rt

Head water

Inle t

Outl et

Fl ow

Nor mal

Criti cal

Out let

Tailw ater

Outl et

Tailw ater arge (cfs)

Disch arge (cfs)

Elevat ion (ft)

Cont rol Dep th (ft)

Cont rol Dep th (ft)

Ty pe

Dep th (ft)

Dep th (ft)

De pth (ft)

Dept h (ft)

Velo city (ft/s

Veloc ity (ft/s)

2.00 cfs

2.00 cfs

1543.4

0.51 0.0* 1- S2 n

0.21 0.53 0.2

0.17 13.0

3.91

4.00 cfs

4.00 cfs

1543.6

0.73 0.0* 1- S2 n

0.30 0.77 0.3

0.20 15.9

5.05

* Full Flow Headwater elevation is below inlet invert.

Culvert Barrel Data

Culvert Barrel Type Straight Culvert

Inlet Elevation (invert): 1542.92 ft, Outlet Elevation (invert): 1533.17 ft

Culvert Length: 17.89 ft, Culvert Slope: 0.6501

Culvert Performance Curve Plot: 18" CMP-#2

Water Surface Profile Plot for Culvert: 18" CMP-#2

Site Data - 18" CMP-#2

Inlet Station: 0.00 ft

Inlet Elevation: 1542.92 ft

Outlet Station: 15.00 ft

Outlet Elevation: 1533.17 ft

Number of Barrels: 1

Culvert Data Summary - 18" CMP-#2

Barrel Shape: Circular

Barrel Diameter: 1.50 ft

Barrel Material: Corrugated Steel

Inlet Configuration: Thin Edge Projecting

Inlet Depression: None

Tailwater Data for Crossing: 18" CMP

Table 2 - Downstream Channel Rating Curve (Crossing: 18" CMP)

Flow (cfs) Water Surface Elev (ft)

Velocity (ft/s)

Depth (ft) Shear (psf) Froude Number

2.00 1520.02 0.17 3.91 6.85 2.68

4.00 1520.05 0.20 5.05 8.28 2.86

Tailwater Channel Data - 18" CMP

Tailwater Channel Option: Irregular Channel

Channel Slope: Irregular Channel

User Defined Channel Cross-Section

Coord No. Station (ft) Elevation (ft) Manning's n

1 0.00 1534.00 0.0750 2 4.73 1533.00 0.0750 3 6.00 1532.70 0.0750 4 6.58 1532.59 0.0750 5 9.88 1532.00 0.0750 6 11.63 1531.69 0.0750 7 13.26 1531.25 0.0750 8 14.54 1531.00 0.0750 9 18.51 1530.28 0.0750 10 21.54 1530.00 0.0750 11 22.86 1530.00 0.0750 12 25.78 1529.93 0.0750 13 28.40 1529.97 0.0750 14 32.43 1529.57 0.0750 15 35.14 1529.34 0.0750 16 37.25 1529.00 0.0750 17 40.50 1528.62 0.0750 18 41.83 1528.51 0.0750 19 42.90 1528.26 0.0750 20 44.20 1528.00 0.0750 21 48.25 1527.20 0.0750 22 48.78 1527.00 0.0750 23 51.07 1526.00 0.0750 24 53.24 1525.00 0.0750 25 54.20 1524.62 0.0750 26 54.38 1524.56 0.0500 27 55.72 1524.28 0.0500

28 57.07 1524.00 0.0500 29 61.35 1523.00 0.0500 30 61.93 1522.85 0.0500 31 62.63 1522.69 0.0500 32 63.60 1522.40 0.0500 33 65.27 1522.00 0.0500 34 69.71 1521.00 0.0500 35 70.42 1520.80 0.0500 36 73.16 1520.00 0.0500 37 76.88 1519.85 0.0500 38 77.87 1520.00 0.0500 39 80.54 1519.99 0.0500 40 84.25 1520.42 0.0500 41 86.59 1521.00 0.0500 42 88.52 1521.63 0.0500 43 89.81 1522.00 0.0500 44 91.09 1522.31 0.0500 45 93.01 1523.00 0.0500 46 93.04 1523.01 0.0500 47 95.43 1524.00 0.0500 48 97.55 1525.00 0.0500 49 99.82 1526.00 0.0500 50 100.45 1526.28 0.0500 51 102.29 1527.00 0.0500 52 104.53 1528.00 0.0500 53 104.62 1528.03 0.0500 54 107.01 1529.00 0.0750 55 109.30 1530.00 0.0750 56 109.40 1530.04 0.0750 57 110.72 1530.70 0.0750 58 111.27 1531.00 0.0750 59 111.27 1531.00 0.0750 60 113.16 1532.00 0.0750 61 114.93 1533.00 0.0750 62 116.80 1534.00 0.0750 63 117.29 1534.23 0.0750 64 118.19 1534.75 0.0750 65 118.50 1535.00 0.0750 66 119.60 1536.00 0.0750 67 120.73 1537.00 0.0750 68 121.83 1538.00 0.0750 69 123.03 1539.00 0.0750 70 123.82 1539.70 0.0750 71 124.35 1540.00 0.0750 72 124.41 1540.03 0.0750 73 125.59 1541.00 0.0750 74 126.68 1542.00 0.0750 75 127.97 1543.00 0.0750 76 129.11 1544.00 0.0750 77 129.91 1544.60 0.0750

78 130.59 1544.86 0.0750 79 131.52 1545.00 0.0000

Roadway Data for Crossing: 18" CMP

Roadway Profile Shape: Constant Roadway Elevation

Crest Length: 200.00 ft

Crest Elevation: 1550.00 ft

References

1. Ariane Jong-Levinger, Tirtha Banerjee, Douglas Houston, and Brett F. Sanders 2022. Compound

Post-Fire Flood Hazards Considering Infrastructure Sedimentation. Compound Post‐Fire Flood

Hazards Considering Infrastructure Sedimentation - Jong‐Levinger - 2022 - Earth's Future - Wiley

Online Library

2. Hydraulic Design Series No. 2, Second Edition. Highway Hydrology. HDS-2 - Highway Hydrology -second edition (dot.gov)

3. Current Precipitation Frequency Information and Documents for Oregon State.

Atlas2_Volume9.pdf (noaa.gov)

4. ODOT, 2014. Oregon Department of Transportation, Hydraulics Design Manual. Oregon

Department of Transportation : Hydraulics Design Manual : Hydraulics : State of Oregon https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2022EF002670#:~:text=Roughly%20speaking%2C%20a%20bulking%20factor,flows%20(Gusman%2C%202011) https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2022EF002670#:~:text=Roughly%20speaking%2C%20a%20bulking%20factor,flows%20(Gusman%2C%202011) https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2022EF002670#:~:text=Roughly%20speaking%2C%20a%20bulking%20factor,flows%20(Gusman%2C%202011) https://www.fhwa.dot.gov/engineering/hydraulics/pubs/hif02001.pdf https://www.fhwa.dot.gov/engineering/hydraulics/pubs/hif02001.pdf https://hdsc.nws.noaa.gov/pub/hdsc/data/papers/Atlas2_Volume9.pdf https://www.oregon.gov/odot/hydraulics/Pages/Hydraulics-Manual.aspx https://www.oregon.gov/odot/hydraulics/Pages/Hydraulics-Manual.aspx