WY_26(1)_Red Grade Road_Hydraulics Memo.pdf

Subject: WY FLAP SHE 26(1) Red Grade Road – Final Hydraulics Memorandum Date: October 2023

To: Julia Dietsch, PE, Project Manager, CFLHD

From: Aaron Estep, PE, Hydraulic Engineer, CFLHD Signature: ________________________

Through: Luis Calderón, PE, CFM, Hydraulics Team Lead, CFLHD Signature: ________________________

This memorandum presents a summary of the hydrologic and hydraulic analysis completed for Red Grade Road.

The project section of Red Grade Road (Forest Road 26) is located in Sheridan County, Wyoming approximately 7 miles southwest of Big Horn. The approximately 2.5 mile section depicted below is proposed for widening, resurfacing, and drainage improvements. Within the project section, 18 cross culverts (C01-C18), 5 parallel culverts (P01-P05), and one minor pedestrian bridge (B01) were identified. In addition to the existing structures, an irrigation ditch runs along the western side of the road beginning downstream of the C03 crossing, draining under Red Grade Road at C02, and continuing towards the parking lot at the start of the project section. A crossing location map is included in Appendix A. The pedestrian bridge was assumed to be left as is while the remaining culverted crossings were evaluated using the Rational Method and an inlet control analysis.

HYDRAULIC DESIGN CRITERIA

The design and analysis of the existing culverted crossings evaluated for this project were developed in accordance with the design criteria outlined in the Federal Lands Highway Project Development and Design Manual (Federal Lands Highway 2012). Per the PDDM, the road is assumed to be a low standard road and thus cross culverts are designed to the 25-year event while parallel (approach) culverts are designed to the 10-year event. The target HW/D ratio will be 1.5 or less in accordance with the PPDM. Finally, the PDDM recommends a minimum 24-in diameter pipe for all cross culverts and 18-in diameter pipes for parallel culverts.

HYDROLOGIC ANALYSIS

As stated previously, the Rational Method was used to determine flow rates at the existing culverted crossings.

For these calculations, basins were delineated using a 3m DEM obtained from the National Map. A runoff coefficient of 0.2 was assumed for all basins corresponding to "Unimproved Areas" in HDS-2, Table 5.7 (Federal Highway Administration 2002). Time of concentration were computed using basin data and the Kirpich Method for overland flow on grassy earth with a minimum of 5-min used. Rainfall intensities were developed based on the computed time of concentration and site-specific NOAA Atlas 2 precipitation data. Intensity-Duration- Frequency (IDF) curves were develop using the Hydraulic Toolbox, Version 5.0 (Federal Highway Administration 2020) and assumed Wyoming Region 1 (east of the Continental Divide) and a mean basin elevation of 6500-ft.

The resulting 25-year peak flow rates for all cross culverts and 10-year peak flows for all parallel culverts were computed and can be found in Appendix B along with the delineated basin maps.

HYDRAULIC ANALYSIS

To determine replacement pipe size recommendations, an inlet control analysis was performed for all culverts using HY-8 (Federal Highway Administration 2021). The assumption of inlet control conditions is based on the steep slopes observed on site. All culvert proposed for replacement except two exceeded 5% in slope and acted as ditch relief culvert with no downstream tailwater conditions. The analysis assumes inlet control conditions with a mitered inlet configuration (Ke = 0.7) which is conservative for a headwall inlet condition. The proposed pipes will all be installed with a minimum 1 ft of cover. For all 24” pipes, 1 ft of cover meets the 1.5 HW/D ratio targeted for minor culverts. For the two 36” pipes, HW/D will be checked in future plan sets confirm these conditions are met.

RECOMMENDATIONS

Based on the analysis described above, recommendations for each structure are provided in the table below.

Generally, ditch relief culverts are recommended to be installed with L-shaped headwalls to reduce bypass flows and be more resilient to maintenance operations. The existing inlets on many pipes have been damaged from road blading. Installation of new pipe culverts may also require rock removal as a bed rock was observed in the road surface throughout the project section. Discussion with the CFT indicated that this should not be an issue as rock removal will already be required on this project. Several additional location specific comments/recommendations are provided below.

B01, P01-P05:

The existing pedestrian bridge (B01) is adjacent to Red Grade Road and is assumed to be left in place. No hydrologic or hydraulic analyses were performed for this structure. Also, located within the two lower parking lots are culverts P01-P05. While evaluated, work within the parking lots is outside of the scope of work and the existing culverts will be left as is.

C02:

The existing culvert at C02 conveys the irrigation ditch flow below Red Grade Road. Field observations indicate that flow splits immediately upstream of the C02 culvert with excess flows continuing down the natural channel.

It is assumed that only base flow/irrigation flow from the Red Grade Spring is conveyed by this culvert. Hydraulics has coordinated with Sheridan County on this structure and confirmed replacement. No mitigation is required for temporary disruption of service during replacement. For this reason, it is recommended that this structure be replaced in kind to maintain existing irrigation flow conditions. Flared end sections are recommended at both ends of the structure, but riprap is not required at the outlet.

C04:

Hydrologic and hydraulic analyses indicated that the culvert crossing C04 should be upsized from a 36” to a 48” pipe. Cover over this pipe was limited and discussions with the project partners at the 30% field review indicated that the 36” was sufficient in this location. Therefore, it is recommended that C04 be replaced in kind and not upsized to a 48” pipe.

C08:

Hydrologic analysis and field observations indicated that the culvert C08 would be more effective shifted up Red Grade Road to split the area with C07 and intercept flows before the turn. Therefore, it is recommended that C08 be shifted approximately 80-ft up Red Grade Road as depicted below.

Ditch Between C15/C16:

Survey information indicates that storm flows at the hairpin turn between C15 and C16 both drain southeast down the hillslope and at least partially continues down the road to the culvert at C15. In this location, it is recommended that the left ditch be graded as depicted in blue below such that storm flow is directed to the left ditch and discharged prior to reaching C15.

C16:

The C16 culvert receives ditch flow from both directions and is located within a road sag. For this reason, its is recommended that the culvert be installed with a standard headwall as compared to an L-shaped headwall recommended in other locations.

C19 – C22:

During the 30% field review, additional ditch relief culvert needs were identified. The stretch of Red Grade Road between the existing C06 and C07 culverts had multiple areas of rills develop across the road surface as ditch capacity was exceeded. This stretch was approximately 700-ft between culverts while spacing between culverts on similar sections was around 100-200 feet. This section also includes an active slide so conveying flows across the road more often will help to reduce saturation within this area. For these reasons, four additional ditch culverts are recommended to provide additional ditch relief.

C23:

Recently constructed is a new parking lot just north of the proposed C23 crossing. The parking lot is located within a small bowl in the hillside and ditch flows are draining into the bowl resulting in ponding and with little to no outflow due to the topography. To reduce flows conveyed into the existing parking area, an additional ditch culvert (C23) is proposed immediately above the parking lot entrance to direct flows away from the parking area.

Crossing Recommendations:

Outlet Protection:

All culverts that are being replaced are recommended to include riprap aprons at the outlets. Several culvert slopes exceed the maximum 10% recommended by C251-50 detail. Of these culverts, all but one requires smaller than 24-inch pipes based on the hydraulic analysis and thus are not flowing at full design capacity. The one crossing in which a 24-inch pipe is required, was observed to be stable at the outlet during the 30% field review and thus a standard apron is recommended. Therefore, all crossings proposed for replacement in the table above are recommended to include a standard riprap apron (C251-50) at the outlet to reduce scour below the pipe.

Ditch Recommendations:

As part of this project, ditches were evaluated for capacity and stability requirements. Due to the steep slopes along nearly the entire length of the project section, riprap lining is recommended. Using a Manning’s roughness of 0.07 to represent riprap (HEC-15, Table 2.2), a typical triangular ditch was evaluated and assumed a foreslope and backslope of 1V:2H. Using these dimensions, the 10-yr ditch design storm, and the maximum slope of each ditch segment, a normal depth flow calculation was computed. This resulted in ditch flow depths of between 0.3 and 1.0 feet (3.6 and 12 inches). Due to the steep slopes along nearly the entire length of the project section, shear calculations resulted in large riprap sizes to remain stable under these conditions. Existing site conditions during the 30% field review indicated that rock sizes in the range of Class 1 riprap is remaining in place while gravel and smaller sediment are washing out. For this reason, Class 1 riprap appears sufficient to remain stable despite the higher shears computed. Additionally, Class 1 riprap will result in a significant improvement in ditch lining materials and ditch stability overall. Therefore, ditches throughout the project area should be designed with a depth of 1 ft, maximum foreslopes and backslopes of 1V:2H, and all ditches should be lined with Class 1 riprap.

Diameter (in)

Number of Barrels

Structure Type

B01 ---- Not Evaluated No Work Proposed ---- ---- ---- ---- ---- C01 12 Adequate Replace with Recommended Structure 24 1 CMP L-Shaped HW FES C02 12 Not Evaluated Replace in Kind 12 1 CMP FES C03 12 Adequate Replace with Recommended Structure 24 1 CMP L-Shaped HW FES C04 36 Upsize Needed Replace in Kind 36 1 CMP FES FES C05 18 Adequate Replace with Recommended Structure 24 1 CMP L-Shaped HW FES C06 16 Upsize Needed Replace with Recommended Structure 24 1 CMP L-Shaped HW FES C07 12 Adequate Replace with Recommended Structure 24 1 CMP L-Shaped HW FES C08 Unk Unknown Replace with Recommended Structure 24 1 CMP L-Shaped HW FES C09 18 Adequate Replace with Recommended Structure 24 1 CMP L-Shaped HW FES C10 12 Adequate Replace with Recommended Structure 24 1 CMP L-Shaped HW FES C11 8 Upsize Needed Replace with Recommended Structure 24 1 CMP L-Shaped HW FES C12 12 Adequate Replace with Recommended Structure 24 1 CMP L-Shaped HW FES C13 18 Adequate Replace with Recommended Structure 24 1 CMP L-Shaped HW FES C14 18 Adequate Replace with Recommended Structure 24 1 CMP L-Shaped HW FES C15 18 Adequate Replace with Recommended Structure 24 1 CMP L-Shaped HW FES C16 15 Upsize Needed Replace with Recommended Structure 24 1 CMP HW Only FES C17 18 Upsize Needed Replace with Recommended Structure 36 1 CMP FES FES C18 18 Upsize Needed No Work Proposed ---- ---- ---- ---- ---- P01 24 Adequate No Work Proposed ---- ---- ---- ---- ---- P02 12 Adequate No Work Proposed ---- ---- ---- ---- ---- P03 12 Adequate No Work Proposed ---- ---- ---- ---- ---- P04 18 Upsize Needed No Work Proposed ---- ---- ---- ---- ---- P05 18 Adequate No Work Proposed ---- ---- ---- ---- ---- P06 18 Adequate Replace with Recommended Structure 18 1 CMP FES FES C19 ---- New Pipe Install New Pipe 24 1 CMP L-Shaped HW FES C20 ---- New Pipe Install New Pipe 24 1 CMP L-Shaped HW FES C21 ---- New Pipe Install New Pipe 24 1 CMP L-Shaped HW FES C22 ---- New Pipe Install New Pipe 24 1 CMP L-Shaped HW FES C23 ---- New Pipe Install New Pipe 24 1 CMP L-Shaped HW FES

1 - FES: Flared End Section. HW/WW: Headwall and Wingwalls.

Outlet1

Configuration

Proposed Replacement Structure Inlet1

Configuration Crossing

Identifier Hydraulic Adequacy of Existing Structure

Recommended Action Existing

Diameter (in)

REFERENCES

Federal Highway Administration. 2021. HY-8 Culvert Analysis Program, 7.70.1.0. Version 7.60.

Federal Highway Administration. 2002. "Hydraulic Design Series No. 2, Second Edition, Highway Hydrology."

Federal Highway Administration. 2020. "Hydraulic Toolbox 5.0."

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

https://flh.fhwa.dot.gov/resources/design/pddm/.

FHWA. 2005. "Hydraulic Engineering Circular No. 15, Third Edition, Design of Roadside Channels with Flexible Linings."

Appendix A Existing & Proposed Crossing Information

Existing Crossing Inventory:

Overall Site Map:

White crossing labels represent existing crossings; red labels represent proposed (new or shifted) crossings.

Diameter (in)

Number of Barrels

B01 ---- ---- Bridge Parallel Pedestrian bridge. Assume leaving as is.

C01 12 1 CPP Cross 5726.4 5723.3 40.7 0.076 C02 12 1 CMP Cross 5897.5 5891.6 60.8 0.098 Irrigation culvert. Assuming storm flow bypasses culvert.

C03 12 1 CMP Cross 5967.6 5964.5 27.2 0.116 Irrigation culvert. Assuming storm flow bypasses culvert.

C04 36 1 CMP Cross 5970.7 5967.7 42.8 0.068 C05 18 1 CMP Cross 6053.1 6049.8 33.8 0.097 C06 16 1 CMP Cross 6087.9 6082.3 38.9 0.145 C07 12 1 CPP Cross 6273.8 6271.2 26.9 0.095 C08 Unk 1 Unk Cross Unk 6287.6 Unk Unk Approximate culvert location noted in survey data.

C09 18 1 CMP Cross 6408.2 6403.5 50.5 0.093 C10 12 1 CMP Cross 6506.7 6504.4 30.6 0.078 C11 8 1 DIP Cross 6576.6 6572.0 34.2 0.135 C12 12 1 CMP Cross 6630.9 6626.8 41.5 0.100 C13 18 1 CMP Cross 6693.4 6689.6 40.0 0.094 C14 18 1 CMP Cross 6715.8 6692.7 68.5 0.337 Inlet noted as crushed. Approx outlet (buried) location C15 18 1 CMP Cross 6836.5 6833.9 40.7 0.063 Inlet noted as crushed.

C16 15 1 CPP Cross 6986.4 6984.2 30.2 0.073 C17 18 1 DIP Cross 7010.3 7010.1 39.4 0.007 C18 18 1 CMP Cross 7056.0 7055.1 35.4 0.026 Outside of survey topo limits (l ikely outside of project P01 24 1 CMP Parallel 5704.7 5692.7 70.1 0.171 Culvert within parking lot.

P02 12 1 HDPE Parallel 5718.5 5718.4 9.2 0.010 Culvert within parking lot.

P03 12 1 DIP Parallel 5720.6 5720.2 20.3 0.018 Culvert within parking lot.

P04 18 1 CMP Parallel 5723.4 5720.3 50.0 0.061 Culvert within parking lot.

P05 18 1 CMP Parallel 5968.9 5964.4 40.6 0.110 Culvert within parking lot.

P06 18 1 CMP Parallel 7010.9 7011.2 18.7 -0.016 C19 ---- ---- ---- Cross ---- Proposed new pipe culvert.

C20 ---- ---- ---- Cross ---- Proposed new pipe culvert.

C21 ---- ---- ---- Cross ---- Proposed new pipe culvert.

C22 ---- ---- ---- Cross ---- Proposed new pipe culvert.

C23 ---- ---- ---- Cross ---- Proposed new pipe culvert.

Comments/Notes Existing

Structure Type

Inlet Invert Elevation

(ft)

Outlet Invert Elevation

(ft)

Length (ft)

Slope (ft/ft)

Existing Structure

Orientation

Ex. Structure Size Crossing

Identifier

Site Map (C01-C05, P01-P05, B01):

White crossing labels represent existing crossings; red labels represent proposed (new or shifted) crossings.

Site Map (C06-C23, P06):

White crossing labels represent existing crossings; red labels represent proposed (new or shifted) crossings.

Approx Irrigation Ditch

Appendix B Hydrologic Analysis

Culvert Rational Method Calculations:

Basin Delineation Map (C01, C03, P01-P04):

Drainage Area (ac)

Runoff Coefficient

Tc (min)

Design Intensity

(in/hr)

Design Flow (cfs)

B01 ---- ---- ---- ---- ---- Not Evaluated ---- C01 0.8 0.20 8.4 3.74 0.6 Rational Method 0.6 C02 ---- ---- ---- ---- ---- Not Evaluated ---- C03 0.5 0.20 5.0 4.43 0.5 Rational Method 0.5 C04 146.1 0.20 13.8 3.04 88.8 Rational Method 88.8 C05 2.5 0.20 5.2 4.38 2.2 Rational Method 2.2 C06 10.7 0.20 5.5 4.31 9.2 Rational Method 9.2 C07 1.9 0.20 7.5 3.90 1.5 Rational Method 1.5 C08 1.2 0.20 5.0 4.43 1.1 Rational Method 1.1 C09 2.1 0.20 6.7 4.06 1.7 Rational Method 1.7 C10 2.6 0.20 5.0 4.43 2.3 Rational Method 2.3 C11 1.7 0.20 5.0 4.43 1.5 Rational Method 1.5 C12 3.1 0.20 5.1 4.41 2.7 Rational Method 2.7 C13 0.9 0.20 5.0 4.43 0.8 Rational Method 0.8 C14 1.6 0.20 5.7 4.28 1.3 Rational Method 1.3 C15 2.4 0.20 5.5 4.30 2.0 Rational Method 2.0 C16 10.5 0.20 9.8 3.52 7.4 Rational Method 7.4 C17 110.0 0.20 28.4 2.07 45.6 Rational Method 45.6 C18 14.8 0.20 12.0 3.23 9.6 Rational Method 9.6 P01 21.9 0.20 16.0 2.38 10.5 Rational Method 10.5 P02 1.2 0.20 5.0 3.74 0.9 Rational Method 0.9 P03 1.2 0.20 5.0 3.74 0.9 Rational Method 0.9 P04 21.8 0.20 13.8 2.56 11.2 Rational Method 11.2 P05 0.5 0.20 5.0 3.74 0.4 Rational Method 0.4 P06 11.3 0.20 11.9 2.74 6.2 Rational Method 6.2 C19 6.1 0.20 5.8 4.25 5.2 Rational Method 5.2 C20 1.0 0.20 5.0 4.43 0.9 Rational Method 0.9 C21 14.1 0.20 6.1 4.18 11.8 Rational Method 11.8 C22 7.1 0.20 6.5 4.10 5.8 Rational Method 5.8 C23 4.0 0.20 5.2 4.38 3.5 Rational Method 3.5

1 - Design flow is the 25-year storm for all cross culverts (B01, C01-C23) and the 10-year storm for parallel culverts (P01-P06).

2 - Pedestrian bridge (B01) will not be impacted and thus was not evaluated.

3 - Flows into C02 are controlled by a diversion structure immediately upstream and was not evaluated hydrologically.

Crossing Data Rational Method Selected

Design Flow1

(cfs)

Selected Hydrologic

Method

Basin Delineation Map (C04-C16, C19-C23):

Basin Delineation Map (C17, C18, P01):

Ditch Rational Method Calculations:

NOAA Atlas 2 & Rational Method Rainfall Intensity Computations:

10-YR Intensity-Duration-Frequency Equation: 25-YR Intensity-Duration-Frequency Equation:

Segment

Segment Station (Start)

Segment Station (End)

Road Side1

Flow Direction

Drainage Area (ac)

Runoff Coefficient

Tc (min)

Design Intensity

(in/hr)

Design Flow (cfs)

D-C01 151+70 161+60 Right Downstation 0.8 0.20 8.4 3.16 0.5 Rational Method 0.5 D-OUT1 162+00 166+40 Right Downstation 12.8 0.20 8.6 3.13 8.0 Rational Method 8.0 D-C04 167+20 177+40 Right Downstation 13.2 0.20 9.6 2.99 7.9 Rational Method 7.9 D-C05 177+50 181+00 Right Downstation 2.5 0.20 5.2 3.70 1.9 Rational Method 1.9 D-C06 181+40 185+00 Right Downstation 10.6 0.20 5.0 3.74 7.9 Rational Method 7.9 D-C20 185+00 189+00 Right Downstation 1.0 0.20 5.0 3.74 0.7 Rational Method 0.7 D-C21 189+00 193+00 Right Downstation 14.1 0.20 6.1 3.52 9.9 Rational Method 9.9 D-C19 193+00 199+00 Right Downstation 6.1 0.20 5.8 3.58 4.4 Rational Method 4.4 D-C22 199+00 205+00 Right Downstation 7.1 0.20 7.1 3.35 4.8 Rational Method 4.8 D-C07 205+00 209+00 Right Downstation 1.9 0.20 7.5 3.29 1.3 Rational Method 1.3 D-C08 209+00 213+40 Right Downstation 1.2 0.20 5.0 3.74 0.9 Rational Method 0.9 D-C09 213+60 220+00 Right Downstation 2.1 0.20 6.7 3.42 1.4 Rational Method 1.4 D-C10 220+40 224+60 Right Downstation 2.6 0.20 5.0 3.74 1.9 Rational Method 1.9 D-C11 225+00 228+00 Right Downstation 1.7 0.20 5.0 3.74 1.3 Rational Method 1.3 D-C12 228+20 232+20 Right Downstation 3.1 0.20 5.1 3.72 2.3 Rational Method 2.3 D-C13 232+40 233+60 Right Downstation 0.9 0.20 5.0 3.74 0.7 Rational Method 0.7 D-C14 234+00 240+00 Right Downstation 1.6 0.20 5.7 3.61 1.1 Rational Method 1.1 D-C23 242+00 245+60 Right Downstation 4.0 0.20 5.4 3.66 2.9 Rational Method 2.9 D-C15 246+00 251+00 Right Downstation 2.4 0.20 5.5 3.63 1.7 Rational Method 1.7

D-OUT3 252+20 263+00 Left Downstation 5.2 0.20 14.2 2.53 2.6 Rational Method 2.6 D-C16-U 263+00 268+30 Right Upstation 3.2 0.20 7.4 3.31 2.1 Rational Method 2.1 D-C16-D 263+30 277+00 Right Downstation 7.1 0.20 9.6 3.00 4.3 Rational Method 4.3 D-C17 278+00 281+00 Right Upstation 6.2 0.20 8.5 3.15 3.9 Rational Method 3.9

1 - Road side is determined by looking upstation.

2 - Design flow is the 10-year storm.

Ditch Information Rational Method Selected

Design Flow2

(cfs)

Selected Hydrologic

Method

Appendix C Hydraulic Analyses

Inlet Control Analysis Results:

Design Flow1

(cfs) Box Span

(ft) Box Rise

(ft) Diameter

(in) Number of

Barrels

WWA2

(sqft) Diameter

(in)

WWA2

(sqft)

B01 ---- ---- ---- ---- ---- ---- ---- ---- Not Evaluated C01 0.6 1.5 ---- ---- 12 1 0.8 8 0.3 Existing structure size is adequate.

C02 ---- ---- ---- 12 1 0.8 ---- ---- Not Evaluated C03 0.5 1.5 ---- ---- 12 1 0.8 8 0.3 Existing structure size is adequate.

C04 88.8 1.5 ---- ---- 36 1 7.1 48 12.6 Larger structure required.

C05 2.2 1.5 ---- ---- 18 1 1.8 12 0.8 Existing structure size is adequate.

C06 9.2 1.5 ---- ---- 16 1 1.4 24 3.1 Larger structure required.

C07 1.5 1.5 ---- ---- 12 1 0.8 12 0.8 Existing structure size is adequate.

C08 1.1 1.5 ---- ---- Unk 1 Unk 8 0.3 Existing structure size is unknown.

C09 1.7 1.5 ---- ---- 18 1 1.8 12 0.8 Existing structure size is adequate.

C10 2.3 1.5 ---- ---- 12 1 0.8 12 0.8 Existing structure size is adequate.

C11 1.5 1.5 ---- ---- 8 1 0.3 12 0.8 Larger structure required.

C12 2.7 1.5 ---- ---- 12 1 0.8 12 0.8 Existing structure size is adequate.

C13 0.8 1.5 ---- ---- 18 1 1.8 8 0.3 Existing structure size is adequate.

C14 1.3 1.5 ---- ---- 18 1 1.8 12 0.8 Existing structure size is adequate.

C15 2.0 1.5 ---- ---- 18 1 1.8 12 0.8 Existing structure size is adequate.

C16 7.4 1.5 ---- ---- 15 1 1.2 18 1.8 Larger structure required.

C17 45.6 1.5 ---- ---- 18 1 1.8 36 7.1 Larger structure required.

C18 9.6 1.5 ---- ---- 18 1 1.8 24 3.1 Larger structure required.

P01 10.5 1.5 ---- ---- 24 1 3.1 24 3.1 Existing structure size is adequate.

P02 0.9 1.5 ---- ---- 12 1 0.8 8 0.3 Existing structure size is adequate.

P03 0.9 1.5 ---- ---- 12 1 0.8 8 0.3 Existing structure size is adequate.

P04 11.2 1.5 ---- ---- 18 1 1.8 24 3.1 Larger structure required.

P05 0.4 1.5 ---- ---- 18 1 1.8 8 0.3 Existing structure size is adequate.

P06 6.2 1.5 ---- ---- 18 1 1.8 18 1.8 Existing structure size is adequate.

C19 5.2 1.5 ---- ---- ---- ---- ---- 18 1.8 No existing structure.

C20 0.9 1.5 ---- ---- ---- ---- ---- 8 0.3 No existing structure.

C21 11.8 1.5 ---- ---- ---- ---- ---- 24 3.1 No existing structure.

C22 5.8 1.5 ---- ---- ---- ---- ---- 18 1.8 No existing structure.

C23 3.5 1.5 ---- ---- ---- ---- ---- 18 1.8 No existing structure.

1 - Design flow is the 25-year storm for all cross culverts (B01, C01-C23) and the 10-year storm for parallel culverts (P01-P06).

2 - Waterway opening area in square feet.

Crossing Data Target

HW/D

Ratio

Existing Structure Opening Minimum Required Opening

Comments

Ditch Analysis:

Segment

Segment Station (Start)

Segment Station (End)

Road Side1

Flow Direction

Shape Foreslope (__H:1V)

Backslope (__H:1V)

Bottom Width

(ft)

Manning's Roughness

(n-value)

Flow Depth

(ft) Lining Requirement

D-C01 151+70 161+60 Right Downstation Triangular 2.0 2.0 ---- 0.070 0.3 Class 1 Riprap D-OUT1 162+00 166+40 Right Downstation Triangular 2.0 2.0 ---- 0.070 0.9 Class 1 Riprap D-C04 167+20 177+40 Right Downstation Triangular 2.0 2.0 ---- 0.070 1.0 Class 1 Riprap D-C05 177+50 181+00 Right Downstation Triangular 2.0 2.0 ---- 0.070 0.6 Class 1 Riprap D-C06 181+40 185+00 Right Downstation Triangular 2.0 2.0 ---- 0.070 1.0 Class 1 Riprap D-C20 185+00 189+00 Right Downstation Triangular 2.0 2.0 ---- 0.070 0.4 Class 1 Riprap D-C21 189+00 193+00 Right Downstation Triangular 2.0 2.0 ---- 0.070 1.0 Class 1 Riprap D-C19 193+00 199+00 Right Downstation Triangular 2.0 2.0 ---- 0.070 0.8 Class 1 Riprap D-C22 199+00 205+00 Right Downstation Triangular 2.0 2.0 ---- 0.070 0.9 Class 1 Riprap D-C07 205+00 209+00 Right Downstation Triangular 2.0 2.0 ---- 0.070 0.5 Class 1 Riprap D-C08 209+00 213+40 Right Downstation Triangular 2.0 2.0 ---- 0.070 0.4 Class 1 Riprap D-C09 213+60 220+00 Right Downstation Triangular 2.0 2.0 ---- 0.070 0.5 Class 1 Riprap D-C10 220+40 224+60 Right Downstation Triangular 2.0 2.0 ---- 0.070 0.5 Class 1 Riprap D-C11 225+00 228+00 Right Downstation Triangular 2.0 2.0 ---- 0.070 0.5 Class 1 Riprap D-C12 228+20 232+20 Right Downstation Triangular 2.0 2.0 ---- 0.070 0.6 Class 1 Riprap D-C13 232+40 233+60 Right Downstation Triangular 2.0 2.0 ---- 0.070 0.4 Class 1 Riprap D-C14 234+00 240+00 Right Downstation Triangular 2.0 2.0 ---- 0.070 0.5 Class 1 Riprap D-C23 242+00 245+60 Right Downstation Triangular 2.0 2.0 ---- 0.070 0.7 Class 1 Riprap D-C15 246+00 251+00 Right Downstation Triangular 2.0 2.0 ---- 0.070 0.5 Class 1 Riprap

D-OUT3 252+20 263+00 Left Downstation Triangular 2.0 2.0 ---- 0.070 0.7 Class 1 Riprap D-C16-U 263+00 268+30 Right Upstation Triangular 2.0 2.0 ---- 0.070 0.8 Class 1 Riprap D-C16-D 263+30 277+00 Right Downstation Triangular 2.0 2.0 ---- 0.070 0.9 Class 1 Riprap D-C17 278+00 281+00 Right Upstation Triangular 2.0 2.0 ---- 0.070 1.0 Class 1 Riprap

1 - Road side is determined by looking upstation.

Proposed Ditch ConfigurationDitch Information