Hydraulics Tech Memo.pdf

Hydraulics Technical Memorandum Federal Lands Access Program

AZ FLAP 24(1)

King Canyon Trailhead

Federal Lands Access Program (FLAP)

Hydraulics Technical Memorandum with

Off-Site Hydrology

Pima County, Arizona

Prepared for:

U.S. Department of Transportation Federal Highway Administration

Central Federal Lands Highway Division IDIQ Contract No. DTFH68-14-D-00010

July 2020

Prepared by:

JACOBS ENGINEERING GROUP, INC.

707 17th Street, Suite 2300 Denver, Colorado 80202

Project No. WVXY4082

TABLE OF CONTENTS

Page No.

I. Project Description and Location A. Description B. Location

II. Drainage Basins A. Major Basins B. Minor Basins

III. Drainage Design Criteria A. General Criteria B. Hydrologic Criteria C. Hydraulic Criteria

IV. Hydrology A. Major Basins B. Minor Basins. ....................................................................................... …….. 7

V. Hydraulics A. Open Channel Design B. Pipe Culvert Design C. Outlet Protection Design

VI. Conclusion

VII. References

Figures

1 - Location Map 2 – Vicinity Map 3 – Minor Basins Off-Site 4 – Minor Basins On-Site 5 – Project Layout

Appendices

Appendix A Rainfall and Site Data Appendix B Rational Method Hydrology Appendix C Pipe Culvert Computations Appendix D Open Channel Computations i

I. PROJECT DESCRIPTION AND LOCATION

A. DESCRIPTION

The King Canyon Trailhead is located in Pima County, Arizona on Kinney Road North. The existing facility consists of an unpaved parking lot on the north side of the roadway adjacent to an unnamed wash.

The intent of this project is to provide a paved entrance and parking lot. The northern end of the lot will be adjacent to the existing trailhead. The entrance will match the existing Kinney Road pavement and conform with the roadway drainage features. Off-site runoff will be collected and conveyed to a discharge point without altering the natural drainage patterns.

B. LOCATION

The project is located on Kinney Road North in Pima County. It lies south of Saguaro National Park and west of Old Tucson theme park.

The project coordinates are 32° 14' 51" N, 111° 10' 01" W, see Figure

1. The project area is approximately

0.9 acres with a hilly topography and desert vegetation, see Figure 2.

Project Location

Figure 1 – Location Map

Project Site

Figure 2 – Vicinity Map

NORTH

N.T.S.

II. DRAINAGE BASINS

A. MAJOR BASINS

NO MAJOR BASINS WERE IDENTIFIED IN THE PROJECT

B. MINOR BASINS

Two minor basins, designated Off-Site Basin 1 and Off-Site Basin 2, drain to the project site.

These basins are located on the northeast side of the proposed parking lot. It has been delineated using aerial mapping and USGS topographical mapping (7.5 minute quadrant maps), Brown Mountain Quadrangle 2018. The points of concentration are located at the proposed open channels on the north and east sides of the site. These minor basins have an area of 1.25 acres and 1.54 acres. See Figure 3 – Minor Basins Off-Site.

Figure 3 – Minor Basins Off-Site

Off‐Site Basin 1

Trailhead

NORTH

N.T.S.

Off‐Site Basin 2

Four minor basins, designated On-Site Basin 1, On-Site Basin 2, On-Site Basin 3, and On-Ste Basin 4 drain from the project site to the existing drainageways. On-Site Basin 1 drains towards the ravine and concrete box culvert under Kinney Road. Basin 2 drains into Culvert 2. Basin 3 drains into Culvert 3, and Basin 4 discharges to the east as overland flows.

See Figure 4 – Minor Basins On-Site.

Figure 4 – Minor Basins On-Site

III. DRAINAGE DESIGN CRITERIA

A. GENERAL CRITERIA

Drainage criteria for the King Canyon Trailhead project was generally based on the guidelines outlined in FHWA Hydraulic Design Series No. 2 Second Edition, No. 4 Fourth Edition and No.

5 Third Edition. Site specific criteria were based on guidelines of Pima County and the Arizona Department of Transportation.

B. HYDROLOGIC CRITERIA

MAJOR BASINS

NO MAJOR BASINS WERE IDENTIFIED IN THE PROJECT

MINOR BASINS

Minor basins are those with drainage areas less than 100 acres. Runoff computations were based on the Hydraulic Design Series No. 2, Highway Hydrology, Rational Method. This method relies on basin parameters such as soil cover, hydrologic soils group, vegetation, area, length, slope, rainfall and time of concentration. In accordance with project criteria, the design storm is the 50-year event.

Rainfall intensities were obtained from NOAA Atlas 14. Soil characteristics were derived from the Natural Resources Conservation Service. Topography was obtained from aerial mapping and from USGS topographic map Brown Mountain Quadrangle 2018. A review of FEMA flood insurance maps indicated no regulated floodway lies in the project area. The FEMA firmette for the area has been provided. See Appendix A for these site conditions.

C. HYDRAULIC CRITERIA

Culvert design was based on current CFL criteria. Therefore, all drainage structures were designed to meet the following criteria.

Agency Criteria Storm Event CFL Flow Passes under Paved Areas 25-year

IV. HYDROLOGY

A. MAJOR BASINS

NO MAJOR BASINS WERE IDENTIFIED IN THIS PROJECT.

B. MINOR BASINS

For the Rational Method computations, the time of concentration was computed for each basin.

In accordance with design criteria, the minimum value was set at 10 minutes. Peak discharge rates were calculated using the following equation:

Q = C I A where

C = runoff coefficient based on soil type, one hour rainfall, vegetation cover

I = rainfall intensity (inches per hour)

A = basin area (acres)

RESULTS

The Rational Method computations are included in the Appendix B. The results are summarized in the following table.

RATIONAL METHOD BASIN RESULTS

Basin Area (acres) Q25 (cfs) Off-Site 1 1.25 3.4 Off-Site 2 1.54 4.2 On-Site 1 0.20 1.05 On-Site 2 0.15 0.79 On-Site 3 0.09 0.47 On-Site 4 0.14 0.73

V. HYDRAULICS

The proposed drainage improvements for the King Canyon Trailhead project are shown in Figure

5. Off-site runoff flowing from north to south will be intercepted by open channels. This runoff will then be conveyed westerly to a proposed pipe culvert lying under the parking lot and southerly to an existing wash. On-site runoff will be collected by a catch basin or sheet flow off to an open channel. The outlets of the culverts will be protected with riprap aprons. The proposed drainage design will accomplish the following objectives:

• Provide improved collection of off-site runoff flowing to the project area.

• Intercept flows with unlined open channels.

• Design channel to convey flows at a low velocity to avoid lining requirements.

• Provide a corrugated metal pipes to drain runoff under the parking lot.

• Include riprap aprons at the culvert outlet to mitigate erosion.

Figure 5 – Project Layout

A. OPEN CHANNEL DESIGN

The off-site runoff collector channel will be constructed as unlined ditches with side slopes and bottom widths as shown below. Riprap protection was required where the design velocity exceeds 4 feet per second. The computations were based on Manning’s Equation using a n value of 0.035 per ADOT standards. See Appendix C for detailed calculations.

Location Sideslopes Bottom Width (ft) Slope (ft/ft) Q25 (cfs) Depth (ft) Velocity (fps)

Channel 1 2:1 2:1 2.0 0.0800 3.4 0.30 4.55 Channel 2 2:1 2:1 2.0 0.0092 4.3 0.33 5.14 Channel 3 2:1 2:1 0.0 0.0050 5.4 1.18 1.96 Channel 4 4:1 2:1 0.0 0.0050 1.2 1.18 1.76

B. PIPE CULVERT DESIGN

The collector channel runoff will be drained by a corrugated metal pipe culverts (CMP) of the size indicated. A minimum of 12” of cover will be provided at the culvert. In addition end sections will be provided at the pipe inlet and outlet. The pipe was designed using HY8. Tailwater depths were set at 0.6 pipe diameter. The results including computed HW/D are summarized in the following table. Headwater depth will be at least 12” below pavement elevation at the entrance.

PIPE CULVERT RESULTS

Location Q25 (cfs) Diameter Length (ft) Slope (ft/ft) HW/D Culvert 1 3.4 1@18” 68 0.0294 0.65 Culvert 2 1.0 1@18” 128 0.0551 0.36 Culvert 3 0.5 1@18” 46 0.0250 0.36

C. OUTLET PROTECTION DESIGN

To protect against erosion and scour, it is proposed to construct a riprap apron at the outlet of pipe culverts. The aprons have been designed in accordance with HEC-14, Hydraulic Design of Energy Dissipators for Culverts and Channels and standard CFLHD plans. The 25-year peak discharges were considered the design flow. Following is a summary of the proposed riprap apron design. It is recommended the sizes and depths in the table below to be minimums. See Appendix D for detailed computations.

RIPRAP APRON RESULTS

Location D 50 (in) L A (ft) Apron Depth Width (3D) W A (ft) Vol (cu yd) Culvert 1 6 6 1.65 5 9 2.2

Culverts 2&3 6 6 1.65 10 9 4.4

VI. CONCLUSION

The proposed improvements to the King Canyon Trailhead require installation of a drainage system. The existing roadside ditches and wash crossings within the project limits will not be affected. The drainage recommendations detailed in this report will greatly improve drainage conditions at the trailhead. An all-weather parking facility will be provided and greatly improve the transportation considerations of the project. These proposed improvements are based on using current hydrologic and hydraulic methodologies.

VII. REFERENCES

1. Federal Lands Highway, Project Development and Design Manual (PDDM), Federal Highway Administration, January 2014

2. Scoping Summary, AZ FLAP 24 (1), King Canyon Trailhead Jacobs Engineering, July

3. Highway Drainage Design Manual, Arizona Department of Transportation, January 2007

4. NOAA Atlas 14, Volume 1, Version 5, National Oceanic and Atmospheric Administration

5. 7.5 min. series, Topographic Maps, US Geological Survey, Brown Mountain Quadrangle

6. Federal Highway Administration Hydraulic Design Series No. 2, Highway Hydrology, latest revision

7. Federal Highway Administration HY-8 ver 7.2, August 23, 2011

8. Drainage Design Manual for Maricopa County, Volume 2, January 28, 1996

9. Erosion and Sediment Control, Surface Mining in the Eastern US, US Environmental

Protection Agency, 1976

APPENDIX A

RAINFALL AND SITE DATA

APPENDIX B

RATIONAL METHOD HYDROLOGY

0.49

2.16

APPENDIX C

PIPE CULVERT COMPUTATIONS

HY-8 Culvert Analysis Report

Crossing Discharge Data

Discharge Selection Method: Specify Minimum, Design, and Maximum Flow

Minimum Flow: 3.4 cfs

Design Flow: 3.4 cfs

Maximum Flow: 3.4 cfs

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

Headwater Elevation

(ft) Total Discharge (cfs)

Culvert 1 Discharge (cfs)

Roadway Discharge (cfs) Iterations

2700.98 3.40 3.40 0.00 1

2700.98 3.40 3.40 0.00 1

2700.98 3.40 3.40 0.00 1

2700.98 3.40 3.40 0.00 1

2700.98 3.40 3.40 0.00 1

2700.98 3.40 3.40 0.00 1

2700.98 3.40 3.40 0.00 1

2700.98 3.40 3.40 0.00 1

2700.98 3.40 3.40 0.00 1

2702.40 10.67 10.67 0.00 Overtopping

Table 2 - Culvert Summary Table: Culvert 1

* Full Flow Headwater elevation is below inlet invert.

Straight Culvert

Inlet Elevation (invert): 2700.00 ft, Outlet Elevation (invert): 2698.00 ft

Culvert Length: 68.03 ft, Culvert Slope: 0.0294

Site Data - Culvert 1

Site Data Option: Culvert Invert Data

Inlet Station: 0.00 ft

Inlet Elevation: 2700.00 ft

Outlet Station: 68.00 ft

Outlet Elevation: 2698.00 ft

Number of Barrels: 1

Culvert Data Summary - Culvert 1

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: Square Edge with Headwall

Inlet Depression: None

Total Discharge

(cfs) Culvert

Discharge (cfs)

Headwater Elevation

(ft) Inlet

Control Depth (ft)

Outlet Control

Depth (ft)

Flow Type

Normal Depth (ft)

Critical Depth (ft)

Outlet Depth (ft)

Tailwater Depth (ft)

Outlet Velocity

(ft/s) Tailwater Velocity

(ft/s)

3.40 3.40 2700.98 0.984 0.0* 1-S2n 0.610 0.703 0.610 0.900 5.035 0.000

3.40 3.40 2700.98 0.984 0.0* 1-S2n 0.610 0.703 0.610 0.900 5.035 0.000

3.40 3.40 2700.98 0.984 0.0* 1-S2n 0.610 0.703 0.610 0.900 5.035 0.000

3.40 3.40 2700.98 0.984 0.0* 1-S2n 0.610 0.703 0.610 0.900 5.035 0.000

3.40 3.40 2700.98 0.984 0.0* 1-S2n 0.610 0.703 0.610 0.900 5.035 0.000

3.40 3.40 2700.98 0.984 0.0* 1-S2n 0.610 0.703 0.610 0.900 5.035 0.000

3.40 3.40 2700.98 0.984 0.0* 1-S2n 0.610 0.703 0.610 0.900 5.035 0.000

3.40 3.40 2700.98 0.984 0.0* 1-S2n 0.610 0.703 0.610 0.900 5.035 0.000

Table 3 - Downstream Channel Rating Curve (Crossing: Culvert 1)

Tailwater Channel Data - Culvert 1

Tailwater Channel Option: Enter Constant Tailwater Elevation

Constant Tailwater Elevation: 2698.90 ft

Roadway Data for Crossing: Culvert 1

Roadway Profile Shape: Constant Roadway Elevation

Crest Length: 20.00 ft

Crest Elevation: 2702.40 ft

Roadway Surface: Paved

Roadway Top Width: 24.00 ft

Flow (cfs) Water Surface Elev (ft) Depth (ft)

3.40 2698.90 0.90

3.40 2698.90 0.90

3.40 2698.90 0.90

3.40 2698.90 0.90

3.40 2698.90 0.90

3.40 2698.90 0.90

3.40 2698.90 0.90

3.40 2698.90 0.90

Crossing Discharge Data

Discharge Selection Method: Specify Minimum, Design, and Maximum Flow

Minimum Flow: 1 cfs

Design Flow: 1 cfs

Maximum Flow: 1 cfs

Table 4 - Summary of Culvert Flows at Crossing: Culvert 2

Headwater Elevation

(ft) Total Discharge (cfs) Culvert 2 Discharge

(cfs) Roadway Discharge

(cfs) Iterations

2691.84 1.00 1.00 0.00 1

2691.84 1.00 1.00 0.00 1

2691.84 1.00 1.00 0.00 1

2691.84 1.00 1.00 0.00 1

2691.84 1.00 1.00 0.00 1

2691.84 1.00 1.00 0.00 1

2691.84 1.00 1.00 0.00 1

2691.84 1.00 1.00 0.00 1

2691.84 1.00 1.00 0.00 1

2695.32 12.77 12.77 0.00 Overtopping

Table 5 - Culvert Summary Table: Culvert 2

* Full Flow Headwater elevation is below inlet invert.

Straight Culvert

Inlet Elevation (invert): 2691.30 ft, Outlet Elevation (invert): 2689.50 ft

Culvert Length: 57.03 ft, Culvert Slope: 0.0316

Site Data - Culvert 2

Site Data Option: Culvert Invert Data

Inlet Station: 0.00 ft

Inlet Elevation: 2691.30 ft

Outlet Station: 57.00 ft

Outlet Elevation: 2689.50 ft

Number of Barrels: 1

Total Discharge

(cfs) Culvert

Discharge (cfs)

Headwater Elevation

(ft) Inlet

Control Depth (ft)

Outlet Control

Depth (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 2691.84 0.536 0.0* 1-S2n 0.318 0.373 0.318 0.900 3.656 0.000

1.00 1.00 2691.84 0.536 0.0* 1-S2n 0.318 0.373 0.318 0.900 3.656 0.000

1.00 1.00 2691.84 0.536 0.0* 1-S2n 0.318 0.373 0.318 0.900 3.656 0.000

1.00 1.00 2691.84 0.536 0.0* 1-S2n 0.318 0.373 0.318 0.900 3.656 0.000

1.00 1.00 2691.84 0.536 0.0* 1-S2n 0.318 0.373 0.318 0.900 3.656 0.000

1.00 1.00 2691.84 0.536 0.0* 1-S2n 0.318 0.373 0.318 0.900 3.656 0.000

1.00 1.00 2691.84 0.536 0.0* 1-S2n 0.318 0.373 0.318 0.900 3.656 0.000

1.00 1.00 2691.84 0.536 0.0* 1-S2n 0.318 0.373 0.318 0.900 3.656 0.000

Culvert Data Summary - Culvert 2

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

Inlet Depression: None

Table 6 - Downstream Channel Rating Curve (Crossing: Culvert 2)

Tailwater Channel Data - Culvert 2

Tailwater Channel Option: Enter Constant Tailwater Elevation

Constant Tailwater Elevation: 2690.40 ft

Roadway Data for Crossing: Culvert 2

Roadway Profile Shape: Constant Roadway Elevation

Crest Length: 20.00 ft

Crest Elevation: 2695.32 ft

Roadway Surface: Paved

Roadway Top Width: 33.00 ft

Flow (cfs) Water Surface Elev (ft) Depth (ft)

1.00 2690.40 0.90

1.00 2690.40 0.90

1.00 2690.40 0.90

1.00 2690.40 0.90

1.00 2690.40 0.90

1.00 2690.40 0.90

1.00 2690.40 0.90

1.00 2690.40 0.90

APPENDIX D

OPEN CHANNEL COMPUTATIONS