mt-d201901_DAR2019(1)_HydraulicsMemo_Final.pdf

Prepared for:

WESTERN FEDERAL LANDS HIGHWAY DIVISION

610 East Fifth Street, Vancouver, WA 98661

ADOBE CREEK HYDRAULICS

DESIGN MEMORANDUM

Defense Access Roads FY 2019, MT DAR 2019(1) IDIQ Contract No. DTFH7015D00007

Task Order No. 69056718F000042

March 2019

Prepared by:

ROBERT PECCIA &

ASSOCIATES

Helena, Montana

Robert Peccia and Associates Adobe Creek Hydraulics Design Memorandum March 2019 i

TABLE OF CONTENTS

1.0 Introduction

2.0 This Memorandum

3.0 Drainage Characteristics

4.0 Existing Hydraulic Structures

5.0 Hydrology

5.1 Drainage Basin Delineation

5.2 Design Flood Frequency

5.3 Drainage Culvert Hydrologic Estimates

6.0 Hydraulics

6.1 H-06 Road, M.P. 1.05

7.0 Conclusion

Appendices

Appendix A: Project Map Appendix B: Adobe Creek StreamStats Reports Appendix C: H-06 Road M.P. 1.05 – Adobe Creek Crossing Hydraulic Analyses

March 2019 ii

ABBREVIATIONS/ACRONYMS

ADT average daily traffic

CMP corrugated metal pipe

CMPA corrugated metal pipe arch

DAR Defense Access Roads

FEMA Federal Emergency Management Agency

FHWA Federal Highway Administration

M.P. mile post

PDDM Project Development and Design Manual

Q10 10-year design flow

Q25 25-year design flow

Q50 50-year design flow

RCB Reinforced Concrete Box

RPA Robert Peccia and Associates

SIR Scientific Investigations Report

T-E Transporter – Erector (vehicles)

USAF United States Air Force

USGS United States Geological Survey

WFLHD Western Federal Lands Highway Division

March 2019 1

1.0 INTRODUCTION

The Western Federal Lands Highway Division (WFLHD) of the Federal Highway Administration (FHWA), in cooperation with the US Air Force (USAF) Base at Malmstrom, Montana of the Department of Defense, Cascade County, Chouteau County, and Teton County, is proposing to complete the design documentation for this Defense Access Roads FY 2019 project (MT DAR 2019(1)). The proposed project consists of drainage improvements and re-graveling of the existing Defense Access Roads (DAR) consistent with Transporter-Erector (T-E) Route Standards as agreed upon by the USAF, Counties, and FHWA. Robert Peccia and Associates (RPA) was selected by FHWA to assist in the development of the project.

2.0 THIS MEMORANDUM

The purpose of this memorandum is to investigate possible hydraulic improvement options at the Adobe Creek crossing on H-06 Road (Birdtail Creek Road) at mile post (M.P.) 1.05. The memorandum intends to describe and document the hydraulic analysis and potential drainage improvements options.

3.0 DRAINAGE CHARACTERISTICS

Adobe Creek lies in the northwestern portion of Cascade County near Fort Shaw, Montana and is within the Missouri River watershed. Birdtail Creek Road crosses Adobe Creek twice. Adobe Creek flows into the Sun River just north of Fort Shaw, Montana and the Sun River empties into the Missouri River at the city of Great Falls, Montana. The DAR route within the Adobe Creek drainage is as follows and a general vicinity of the project is depicted in Appendix A:

H-06 Road (Birdtail Creek Road)

The drainage characteristics for the project corridor generally contain more wetlands than typical area elsewhere in central Montana due to the flat topography of the project corridor. The area falls within the Northwest Foothills Region as described in the United States Geologic Survey (USGS) Scientific Investigation Report (SIR) 2015-5019-F. Un-forested buttes, open ridges, and rangeland dominate the area, with both gently-graded and relatively steep drainage basins contributing flow to Adobe Creek.

Adobe Creek is crossed by 5 county roads and US Highway 200 before entering the Sun River. The proposed culvert replacement is in the lower third of the Adobe Creek drainage at M.P. 1.05 on H-06 Road.

Crossings upstream of the replacement include H-06 Road at M.P. 1.80, Dr. Russell Road, Knapstad Road, and South Birdtail Road. Adobe Creek is crossed downstream of the culvert replacement by Clark Street and US Highway 200. About two thirds of the Adobe Creek drainage basin lies upstream of a large irrigation canal which runs along the base of the Shaw and Square Buttes. No significant structures conveying flow across/under the irrigation ditch could be ascertained and it appears that the irrigation ditch intercepts upstream flows diverting them from the project corridor. The entire project corridor is located within Federal Emergency Management Agency (FEMA) floodplain “Zone D” for unmapped areas.

4.0 EXISTING HYDRAULIC STRUCTURES

Existing culvert locations and characteristics were collected for this project in May of 2018 and are presented within the project Culvert Deficiency Report. Additionally, a topographic survey was completed at the Adobe Creek crossing on H-06 Road at M.P. 1.05 in September 2018. All hydraulic analyses are based off this project data.

March 2019 2

The existing crossing at M.P. 1.05 consists of one 60-inch diameter corrugated metal pipe (CMP) and one 78-inch equivalent diameter corrugated metal pipe arch (CMPA). The inlet of the 60-inch CMP shows evidence of uplift and needs to be replaced. Fencing around the inlets of these two pipes is strung with debris indicating water levels at or near road overtop during the spring of 2018. Inquiries with county personnel indicated that the crossing did not overtop in the most recent large event years of 2011 and 2018.

An upstream crossing of Adobe Creek by H-06 road occurs at M.P. 1.80. This crossing consists of one 60-inch diameter CMP and one 84-inch diameter CMP. Both these pipes appear to be in fair condition. The installation of riprap headwall has been recommended for both pipes at this location due to observed fill slope erosion.

5.0 HYDROLOGY

5.1 DRAINAGE BASIN DELINEATION

USGS StreamStats v4 was used to identify and delineate drainage areas contributing flow to the crossing location on H-06 Road at M.P. 1.05. The initial basin delineation resulted in flows that would overtop the crossing at M.P. 1.05 during the 10-year event. Given the input by county personnel, these flows were deemed unrealistically high. It was decided to truncate the delineated basin by the irrigation ditch running along the base of Shaw Butte and Square Butte which intercepts any upstream surface waters. Design flows developed using the truncated delineated basin were used in all hydraulic calculations. Both pre and post truncation drainage basin delineation maps for M.P. 1.05 are included in Appendix B.

5.2 DESIGN FLOOD FREQUENCY

The project roadway has a design speed lower than 45 miles per hour and an Average Daily Traffic (ADT) lower than 1,500 vehicles per day. From this data, the corridor would generally be classified as a low standard road. However, this section of road is classified as a critical access for the missile launch facilities located along the missile base routes. Therefore, per chapter 7.1.6.1 of the FHWA Project Development and Design Manual (PDDM), the roadway can be classified as a High-Standard Road, and the resulting design flood frequency is the 50-year event.

5.3 DRAINAGE CULVERT HYDROLOGIC ESTIMATES

Peak discharges for the drainage basins associated with M.P. 1.05 were determined by using the USGS Rural Regression Equations (Basin and Climatic Characteristics) as described in the USGS SIR 2015- 5019-F. These equations are the most commonly accepted method for estimating peak flows for large watersheds without gages. The project area is in the Northwest Foothills Region of Montana and the variables used in the USGS equations include the drainage basin area and the mean annual precipitation.

Results of the USGS Rural Regression Equations are summarized in Appendix B.

6.0 HYDRAULICS

6.1 H-06 ROAD, M.P. 1.05

The existing structures at the Adobe Creek crossing at M.P. 1.05 include one 60-inch diameter CMP and one 78-inch equivalent diameter CMPA. The low spot of the existing roadway is located roughly 100 ft prior to the 60-inch diameter CMP. At an inlet headwater depth of 2.8 feet, water begins to spread out from the

March 2019 3 main channel to the north along the route. At an inlet headwater depth of 6.3 feet, corresponding to about a 20-year flood event, H-06 Road is overtopped at the low spot.

Hydraulic design calculations for proposed drainage were completed using the HY-8 Culvert Analysis Program and all proposed culverts are designed in accordance with Chapter 7 of the PDDM. Due to the corrosion and alkali soils noted during the initial field inventory work in May 2018, galvanized steel culverts are not recommended.

During the Preliminary Field Review in June of 2018, it was proposed to replace the uplifting 60-inch diameter CMP with another 78-inch equivalent diameter CMPA. The design philosophy used at this crossing was to ensure that the option proposed during the field review would convey the Q10, Q25 and Q50 design flows and if it didn’t, develop a feasible alternative. Hydraulic analysis indicated that the double 78-inch equivalent diameter CMPAs would not pass the Q50 design flow. Larger or more pipes would be required to meet design standards. Installing larger pipes at this location is difficult given the existing embankment heights and cover requirements. Increasing embankment heights would result in significant wetland impacts. Multiple options were analyzed resulting in the smallest structure passing the Q50 design flow while meeting cover requirements with existing embankment heights being a double 9-foot span by 5-foot rise reinforced concrete box (RCB) culvert. Hydraulic analyses are summarized in Appendix C.

During the Plan-in -Hand field review conducted on October 17-18 of 2018, installation of a double 9-foot span by 5-foot rise RCB culvert was discussed. Given the Cascade County input that overtopping has not occurred in the most recent large event years of 2011 and 2018, the USAF decided that replacing the existing 60” CMP with a 87” x 63” CMPA would accomplish their mission of passing the T-E.

7.0 CONCLUSION

Hydrologic analysis was performed for the culvert replacement at M.P. 1.05 on H-06 Road. USGS StreamStats v4 was used to identify and delineate drainage areas contributing flow to the crossing. The delineated drainage basin was truncated given an irrigation channel that appears to intercept upstream flows. The truncated drainage basin area was used to develop design flows.

Hydraulic analysis preformed with the HY-8 Culvert Analysis Program indicate that the existing structures are unable to pass the developed Q50 design flow. Analyses also indicated that the double 87” x 63” CMPA option proposed during the field review was unable to pass the Q50 design flow. It was determined that a double 9-foot span by 5-foot rise RCB culvert would pass the Q50 design flow without alteration of the existing route profile and fit the existing stream channel.

Upon further field review, the USAF decided that replacing the existing 60” CMP with a 87” x 63” CMPA would accomplish their mission of passing the T-E. The double 9-foot span by 5-foot rise RCB culvert will not be used per USAF direction.

APPENDIX A: PROJECT MAP

APPENDIX B: ADOBE CREEK STREAMSTATS REPORTS

StreamStats https://streamstats.usgs.gov/ss/

1 of 3 9/4/2018, 9:07 AM

- Full Basin Delineation

2 of 3 9/4/2018, 9:07 AM

3 of 3 9/4/2018, 9:07 AM

1 of 3 9/4/2018, 10:02 AM

- Truncated Basin Delineation

2 of 3 9/4/2018, 10:02 AM

3 of 3 9/4/2018, 10:02 AM

APPENDIX C: H-06 ROAD M.P. 1.05 - ADOBE CREEK

CROSSING HYDRAULIC ANALYSES

Project:

Project Number:

By:

Date:

Defense Access Roads FY 2019

DAR 2019(1)

S. Markwardt March, 2019

PROPOSED CULVERT HYDRAULIC ANALYSIS

DESIGN FLOWS

Q25 421.0 cfs Q50 629.0 cfs Q100 882.0 cfs

PROPOSED CONDITIONS

Sta. H-06 Road: M.P. 1.05 Area Name Adobe Creek Existing Pipe Rise (in.) 60 (60" dia. CMP)

63 (87" x 63" CMPA)

PIPE DATA

Inv. In (ft) 3502.87 Inv. Out (ft) 3502.71 Length (ft) 48.00 Slope % 0.33 Skew (deg) 10

ROADWAY DATA / SITE DATA

Overtopping Sta. H-06 Road: M.P. 1.05 Overtop elevation (ft) 3509.21 Crest Width (ft) 202 Crest Length (ft) 100 Type Roadway at Sag

OUTLET CHANNEL GEOMETRY

Bottom Width (ft) Channel Slope % 0.0016 Lt. Side Slope (_:1) irregular Rt. Side Slope (_:1) irregular Manning's (n) 0.030

Proposed Culvert Capacity per Hy8 Run 338.81 cfs Ex. CMP & CMPA

Q25 HW Elev. = Q50 HW Elev. = Q25 HW Depth = Q50 HW Depth = D D 1.2D 1.2D Meets Requirements Meets Requirements Notes:

No No

6.69 7.21 5.0' 5.3' 6.0' 6.3'

Q25 HW Check Q50 HW Check Ex. CMP & CMPA Ex. CMP & CMPA

3509.56 3510.08

Table 1 - Summary of Culvert Flows at Crossing: Existing Conditions

Site Data – Existing 60-inch CMP

Site Data Option: Culvert Invert Data

Inlet Station: 0.00 ft

Inlet Elevation: 3503.65 ft

Outlet Station: 48.00 ft

Outlet Elevation: 3503.57 ft

Number of Barrels: 1

Culvert Data Summary – Existing 60-inch CMP

Barrel Shape: Circular

Barrel Diameter: 5.00 ft

Barrel Material: Corrugated Steel

Embedment: 0.00 in

Barrel Manning's n: 0.0240

Culvert Type: Straight

Inlet Configuration: Thin Edge Projecting

Inlet Depression: None

Site Data - Existing 87"x63" CMPA

Site Data Option: Culvert Invert Data

Inlet Station: 0.00 ft

Inlet Elevation: 3502.86 ft

Outlet Station: 48.00 ft

Outlet Elevation: 3502.71 ft

Number of Barrels: 1

Headwater Elevation (ft)

Total Discharge (cfs)

Ex. 60 Discharge (cfs)

Ex 87"x63" CMPA Discharge (cfs)

Roadway Discharge (cfs)

Iterations

3509.56 421.00 132.96 233.19 54.71 8

3509.70 467.10 137.25 239.17 90.48 5

3509.82 513.20 141.04 244.41 127.62 5

3509.92 559.30 144.45 249.10 165.36 4

3510.03 605.40 147.65 252.80 204.65 4

3510.08 629.00 149.18 254.88 224.80 4

3510.22 697.60 153.35 260.61 283.38 4

3510.30 743.70 155.96 264.20 323.37 4

3510.39 789.80 158.04 267.60 364.01 4

3510.47 835.90 159.98 270.82 405.00 4

3510.55 882.00 161.81 273.84 445.79 3

3509.21 338.81 121.60 217.21 0.00 Overtopping

Culvert Data Summary - Existing 87"x63" CMPA

Barrel Shape: Pipe Arch

Barrel Span: 87.00 in

Barrel Rise: 63.00 in

Barrel Material: Steel or Aluminum

Embedment: 0.00 in

Barrel Manning's n: 0.0280

Culvert Type: Straight

Inlet Configuration: Projecting

Inlet Depression: None

Roadway Data for Crossing – Existing Conditions

Roadway Profile Shape: Constant Roadway Elevation

Crest Length: 100.00 ft

Crest Elevation: 3509.21 ft

Roadway Surface: Gravel

Roadway Top Width: 20.00 ft

By:

Date:

Defense Access Roads FY 2019

DAR 2019(1)

S. Markwardt March, 2019

PROPOSED CULVERT HYDRAULIC ANALYSIS

DESIGN FLOWS

Q25 421.0 cfs Q50 629.0 cfs Q100 882.0 cfs

PROPOSED CONDITIONS

Sta. H-06 Road: M.P. 1.05 Area Name Adobe Creek Proposed Pipe Rise (in) 63 Double 87" x 63" CMPA

PIPE DATA

Inv. In (ft) 3502.86 Inv. Out (ft) 3502.71 Length (ft) 50.00 Slope % 0.30 Skew (deg) 7

ROADWAY DATA / SITE DATA

Overtopping Sta. H-06 Road: M.P. 1.05 Overtop elevation (ft) 3509.21 Crest Width (ft) 20 Crest Length (ft) 100 Type Roadway at Sag

OUTLET CHANNEL GEOMETRY

Bottom Width (ft) Channel Slope % 0.0016 Lt. Side Slope (_:1) irregular Rt. Side Slope (_:1) irregular Manning's (n) 0.030

Proposed Culvert Capacity per Hy8 Run 433.90 cfs

CMPA

Q25 HW Elev. = Q50 HW Elev. = Q25 HW Depth = Q50 HW Depth = D D 1.2D 1.2D Meets Requirements Meets Requirements Notes:

Yes No

6.21 6.99 5.3' 5.3' 6.3' 6.3'

Q25 HW Check Q50 HW Check

CMPA CMPA

3509.07 3509.85

Table 1 - Summary of Culvert Flows at Crossing: Double 87"x63" CMPA

Site Data - Existing 87"x63" CMPA

Site Data Option: Culvert Invert Data

Inlet Station: 0.00 ft

Inlet Elevation: 3502.86 ft

Outlet Station: 48.00 ft

Outlet Elevation: 3502.71 ft

Number of Barrels: 1

Culvert Data Summary - Existing 87"x63" CMPA

Barrel Shape: Pipe Arch

Barrel Span: 87.00 in

Barrel Rise: 63.00 in

Barrel Material: Steel or Aluminum

Embedment: 0.00 in

Barrel Manning's n: 0.0280

Culvert Type: Straight

Inlet Configuration: Projecting

Inlet Depression: None

Site Data - New 87"x63" CMPA

Site Data Option: Culvert Invert Data

Inlet Station: 0.00 ft

Inlet Elevation: 3502.86 ft

Outlet Station: 50.00 ft

Outlet Elevation: 3502.71 ft

Number of Barrels: 1

Headwater Elevation (ft)

Total Discharge (cfs)

Ex 87"x63" CMPA Discharge (cfs)

New 87"x63" CMPA Discharge

(cfs)

Roadway Discharge (cfs)

Iterations

3509.07 421.00 210.79 210.28 0.00 3

3509.38 467.10 224.91 224.35 17.61 7

3509.54 513.20 232.13 231.53 49.13 5

3509.67 559.30 238.09 237.46 83.54 5

3509.79 605.40 243.30 242.63 119.34 5

3509.85 629.00 245.75 245.06 137.93 4

3510.00 697.60 251.96 251.59 193.90 5

3510.10 743.70 255.70 254.88 232.88 4

3510.19 789.80 259.49 258.65 271.46 4

3510.28 835.90 263.07 262.18 310.47 4

3510.36 882.00 266.44 265.52 349.89 4

3509.21 433.90 217.21 216.68 0.00 Overtopping

Culvert Data Summary - New 87"x63" CMPA

Barrel Shape: Pipe Arch

Barrel Span: 87.00 in

Barrel Rise: 63.00 in

Barrel Material: Steel or Aluminum

Embedment: 0.00 in

Barrel Manning's n: 0.0280

Culvert Type: Straight

Inlet Configuration: Projecting

Inlet Depression: None

Roadway Data for Crossing: Proposed

Roadway Profile Shape: Constant Roadway Elevation

Crest Length: 100.00 ft

Crest Elevation: 3509.21 ft

By:

Date:

Defense Access Roads FY 2019

DAR 2019(1)

S. Markwardt March, 2019

PROPOSED CULVERT HYDRAULIC ANALYSIS

DESIGN FLOWS

Q25 421.0 cfs Q50 629.0 cfs Q100 882.0 cfs

PROPOSED CONDITIONS

Sta. H-06 Road: M.P. 1.05 Area Name Adobe Creek Proposed Pipe Rise (in) 60 Double 9' x 5' Conc. Box

PIPE DATA

Inv. In (ft) 3502.64 Inv. Out (ft) 3502.46 Length (ft) 36.00 Slope % 0.50 Skew (deg) 4

ROADWAY DATA / SITE DATA

Overtopping Sta. H-06 Road: M.P. 1.05 Overtop elevation (ft) 3509.21 Crest Width (ft) 20 Crest Length (ft) 100 Type Roadway at Sag

OUTLET CHANNEL GEOMETRY

Bottom Width (ft) Channel Slope % 0.0016 Lt. Side Slope (_:1) irregular Rt. Side Slope (_:1) irregular Manning's (n) 0.030

Proposed Culvert Capacity per Hy8 Run 758.62 cfs Conc. Box

Q25 HW Elev. = Q50 HW Elev. = Q25 HW Depth = Q50 HW Depth = D D 1.2D 1.2D Meets Requirements Meets Requirements Notes:

Yes Yes

5.05 5.93 5.0' 5.0' 6.0' 6.0'

Q25 HW Check Q50 HW Check Conc. Box Conc. Box

3507.69 3508.57

Table 1 - Summary of Culvert Flows at Crossing: Double 9' x 5' RCB

Site Data - Double 9' x 5' RCB

Site Data Option: Culvert Invert Data

Inlet Station: 0.00 ft

Inlet Elevation: 3502.64 ft

Outlet Station: 36.00 ft

Outlet Elevation: 3502.46 ft

Number of Barrels: 2

Culvert Data Summary - Double 9' x 5' RCB

Barrel Shape: Concrete Box

Barrel Span: 9.00 ft

Barrel Rise: 5.00 ft

Barrel Material: Concrete

Embedment: 0.00 in

Barrel Manning's n: 0.0120

Culvert Type: Straight

Inlet Configuration: Square Edge (30-75º flare) Wingwall

Inlet Depression: None

Roadway Data for Crossing: Double 9' x 5' RCB

Roadway Profile Shape: Constant Roadway Elevation

Crest Length: 100.00 ft

Crest Elevation: 3509.21 ft

Headwater Elevation

(ft) Total Discharge (cfs) Double Box

Discharge (cfs) Roadway Discharge

(cfs) Iterations

3507.69 421.00 421.00 0.00 1

3507.88 467.10 467.10 0.00 1

3508.07 513.20 513.20 0.00 1

3508.26 559.30 559.30 0.00 1

3508.46 605.40 605.40 0.00 1

3508.57 629.00 629.00 0.00 1

3508.89 697.60 697.60 0.00 1

3509.13 743.70 743.70 0.00 1

3509.33 789.80 779.27 10.11 6

3509.46 835.90 802.90 32.56 6

3509.58 882.00 823.08 58.75 5

3509.21 758.62 758.62 0.00 Overtopping