Physical_Data_-_Final_Hydraulic_Report.pdf

AZ 7A-1(1)

Vista Overlook to Flagstaff

Final Hydraulic Report

Prepared by

Veronica Ghelardi

Technical Services Hydraulic Engineer

Central Federal Lands Highway Division

December 2014 ii

Contents

I. Introduction

A. Project Background and Objectives

II. Hydrologic Analysis and Results of Cross Culverts

III. Cross Culvert Hydraulic Analysis and Results

A. Fry Canyon Arch Culvert

B. Woody Wash Box Culverts

C. 8’ x 6’ Box Culvert

D. Double 6 x 6 Concrete Box Culvert

V. Summary of Recommendations

References:

APPENDIX A

Hydrology

APPENDIX B

Hydraulic Analysis

Table of Figures

Figure 1 Fry Canyon Arch, Looking at Downstream Face of Apron Cut-off Wall

Figure 2 Fry Canyon Arch, Looking Downstream from Apron at Natural Stilling Basin

Figure 3 Woody Wash Box Culverts Upstream Face

Figure 4 8’ x 6’ Box Culvert-Upstream Face

Figure 5 Triple 10’ x 10’ Box Culverts, Landon Springs – Scour at downstream apron

Table of Tables

Table 1. Computed Rational Method peak discharges for DA < =160 acres Table 2: Computed HEC-HMS peak discharges for DA > 160 acres Table 3: Hydraulic Analysis Results

I. Introduction

This hydraulic recommendations report provides a brief overview of the key project elements and summary of the hydrologic and hydraulic analyses that resulted in the selected proposed culverts.

A. Project Background and Objectives

This project is located in the Coconino National Forest, Coconino County, Arizona on SR 89A starting at the Vista Overlook and ending at Old Jackson’s Restaurant near the J.W. Powell interchange. The project is a 4R project that will tie into Arizona Department of

Transportation’s (ADOT) interchange project (slated for construction in 2014) at the north end and tie into ADOT canyon pavement preservation project (which will occur in 2014) at the south end.

There are 5 major culverts and numerous cross culverts (approx. 45) along the route. SR 89A is a high-standard road with an Average Daily Traffic (ADT) of more than 1500 vehicles.

However, at the specific request of ADOT’s George Wallace, the design standard will be the 25-year flood to conform to other ADOT roadways.

Project Design Standards for Culverts, based on ADOT criteria

Capacity and Stability Design: 25-year flood

Design Criteria for Culverts

Headwater o New: Water Surface Elevation (WSEL) ≤ bottom of aggregate base layer o Existing: WSEL ≤ shoulder hinge point

Headwater/Diameter (HW/D) ratio for culverts 48” or smaller: HW/D ≤ 1.5

Headwater/Diameter (HW/D) ratio for culverts larger than 48”: HW/D ≤ 1.2

WSEL limited by unacceptable hazards to property

Minimum Size: 24” for cross-road culverts

Stream Crossings: Match streambed

Cover: Refer to FLH Standard Drawing 602-1 for the minimum and maximum cover on pipes

II. Hydrologic Analysis and Results of Cross Culverts

The Watershed Modeling System (WMS), version 9.0 was used to delineate the drainage basin for each culvert crossing. The peak discharge estimates were computed using NOAA Atlas 14 for the Arizona region and the ADOT Rational Method for the basins up to 160 acres. The

USACE Hydrologic Engineering Center Hydrologic Modeling System (HEC-HMS) was used to determine the discharge for the basins with areas greater than 160 acres.

The Rational Method equation of Q = CiA was used for drainage areas less than or equal to 160 acres, where:

Q = discharge (cfs)

C = runoff coefficient i = average rainfall intensity (in/hr)

A = drainage area (acres)

The time of concentration (Tc) is used to find the rainfall intensity values for the Rational

Method calculation. ADOT’s equation for finding the Tc is:

Tc = 11.4 L 0.5

Kb 0.52

S -0.31 i -0.38

Where: L = length of longest flow path, (mi)

Kb = watershed resistance coefficient

S = slope of longest flow path (ft/mi) i = average rainfall intensity (in/hr) for duration equal to Tc (If Tc < 10 mins, use duration of 10 mins)

For most culverts less than or equal to 48-inches, Central Federal Lands (CFL) hydraulics lead provided the discharge for each basin to the highway design team who then analyzed the culvert capacity using HY-8 v. 7.3. An earlier consultant report identified the need for upsizing a culvert or increasing the number of culverts at a location. These locations were analyzed by the Central

Federal Lands (CFL) hydraulics engineer in addition to the five major culvert structures on the project.

The ADOT drainage manual recommends using US Army Corps of Engineers Hydrologic

Engineering Center’s HEC-1, a flood hydrograph package to estimate the discharge for drainage areas larger than 160 acres. This DOS program is not compatible with current Windows 7 software and the USACE no longer supports the program. Consequently the recommended

USACE HEC-1 successor software program, the Hydrologic Modeling System (HEC-HMS) software, was used.

For drainage areas larger than 160 acres, ADOT recommends using the Clark synthetic hydrograph which requires the use of the Tc, a storage coefficient R, and a time-area relationship.

The project’s location determines which Tc equation to use; in this case the desert/mountain equation:

Tc = 2.4 A -1

LCA

.25

S -.2

Where:

Tc = time of concentration, (hrs)

A = area (sq. mi.)

S = slope (ft/mi)

LCA = length from concentration point on L to point on L perpendicular to the watershed centroid, (mi)

L = length of most hydraulically distant point, (mi)

The results from the preliminary WMS and ADOT Rational Method analysis for the 25-year peak flows for drainage areas less than 160 acres are summarized below in Table 1. Table 2 shows the results of discharges using HEC-HMS model for culvert drainage areas that were larger than 160 acres.

Table 1. Computed Rational Method peak discharges for DA < =160 acres

Culvert

Number Culvert

Station

Drainage

Basin Area

(acres)

25-yr Peak

Discharge

(cfs)

1 15+72 13 12

2 25+62 9 9

3 31+33 0.3 0.34

4 44+24 114 57

5 50+78 13 7

6 55+29 23 15

7 60+57 15 11

8 72+58 19 13

9 77+80 94 63

10 89+76 6 3

11 93+34 70 17

12 96+26 20 13

13 104+76 41 29

14 117+12 8 7

15 122+69 13 9

17 142+73 43 16

18 148+73 8 6

19 154+90 91 53

20 161+72 5 3

22 175+60 11 10

23 183+24 15 11

24 187+48 151 67

25 208+11 3 3

26 218+96 7 6

27 224+32 8 7

28 226+73 4 4

29 230+82 128 23

30 235+32 66 28

31 238+43 18 16

33 255+18 8 8

34 263+10 12 11

35 267+12 4 3

36 285+08 20 14

37 293+07 5 4

38 308+69 82 60

36 323+55 2 2

41 329+24 106 63

42 346+11 2 2

43 352+51 7 6

44 357+31 7 6

45 361+54 1 1

46 365+56 129 81

48 378+15 1 1

49 390+59 1 1

50 399+52 152 88

51 406+55 6 4

52 414+87 23 10

Table 2. Computed HEC-HMS peak discharges for DA > 160 acres

Number Culvert

Station

Drainage

Basin Area

(acres)

25-yr Peak

Discharge

(cfs) 16 132+71 16414 3120

21 166+32 162 180

32 248+38 1965 705

40 326+13 527 110

47 369+30 2590 840

53 431+69 451 190

54 444+10 175 50

III. Cross Culvert Hydraulic Analysis and Results

11 culverts were identified as needing more analysis. Either the earlier consultant report identified a culvert as needing to be upsized, the WMS analysis showed a culvert had a drainage area larger than 160 acres or a culvert was identified as a major hydraulic structure along the route. The locations and descriptions of these culverts are summarized in Table 3.

Most culverts in Table 3 collect flow from drainages west of the roadway except for drainages in the northern part of the project. As noted earlier, the road segment is classified as a high standard road based on criteria in the CFL Project Development Design Manual

(PDDM), however at the request of ADOT, the design standard for culvert discharge is a 25-year flow event. The maximum headwater to depth ratio (HW/D) for culverts 48 inches or smaller is 1.5 and for culverts greater than 48 inches the ratio is 1.2. A summary of the HY-8 culvert hydraulic analysis for the existing major culverts is presented below in Table 3.

Table 3. Hydraulic Analysis Results

Location Culvert Description

Proposed

Upstream

Invert

Elevation

(ft)

Computed

Headwater

Elevation

(ft)

HW

(ft)

HW/

D

Computed

Discharge

(cfs)

132+71 24 x15 Arch Culvert* 6486.24 6501.81 15.57 1.04 3120

166+32 3-42 inch CMP 6583.6 6588.20 4.29 1.23 180

183+24 1-24 inch CMP 6559.8 6653.04 2.34

0.67

187+48 2-42 inch CMP 6670.0 6672.81 2.81 0.80 67

230+82 1-30 inch CMP 6769.8 6773.15 2.73 0.91 23

248+38 2-12 x12 Boxes* 6798.96 6803.81 4.85 0.40 710

326+12 8x6 Box* 6911 6914.78 3.78 0.63 177

365+56 2-36 inch CMP 6862 6865.53 3.53 1.18 81

369+30 3- 10 x10 Boxes* 6850.58 6855.21 4.63 0.46 840

431+69 6x6 Box* 6872.37 6875.98 3.18 0.53 190

444+10 2-30 inch CMP 6901.59 6904.17 2.58 1.03 43

* Major culvert structure.

All dimensions are in feet unless otherwise noted.

A. Fry Canyon Arch Culvert

The concrete arch culvert at Fry Canyon (station 132+71) is a 25’x15’ broken back culvert with wingwalls and concrete aprons at both the inlet and outlet. The concrete arch appears to be in fairly good condition but the downstream wingwalls are cracked and might need to be replaced.

The downstream concrete apron has a 1’x1.5’ hole exposing the rebar, which will need to be repaired. Downstream of the concrete apron is a 4’ drop to the channel bed (see Figure 1) and a naturally formed stilling basin that dissipates energy approximately 5 feet below the initial 4 foot drop (see Figure 2). The stilling basin is surrounded by large boulders, some as large as 3feet in diameter. The Forest Service stated that Fry Canyon arch culvert currently acts as an animal crossing and they would like that to continue. To further protect the cut-off wall, it is proposed that riprap be placed along the face of the cut-off wall and on the slope leading to the stilling basin to fill in any voids. Because the channel flows have made the stilling basin and it appears to be dissipating the flow energy very well, it was decided that it should be left alone. The only modifications will be as noted above to protect the cut-off wall.

Figure 1 Fry Canyon Arch, Looking at Downstream Face of Apron Cut-off Wall

Figure 2 Fry Canyon Arch, Looking Downstream from Apron at Natural Stilling Basin

An unpaved road is located on the west side of the roadway at 127+29 and provides easy access to the upstream end of the concrete arch culvert at Fry Canyon. Because of the easy access to the upstream end of the concrete arch culvert and the natural stilling basin and broken back culvert at the downstream end, there was general consensus by ADOT and CFL to extend the upstream end of the concrete arch culvert and not to disturb the downstream end.

There was also consensus that the concrete arch culvert extension at Fry Canyon should be extended to match the size and shape of the existing structure, rather than a box culvert extension. A box culvert extension is not preferred because it would require forming a transition between the arch and the box to mitigate the turbulence that would be caused by water entering the box and hitting the arch face where the box does not match the arch face.

B. Woody Wash Box Culverts

The double 12’x12’ skewed concrete box culvert at Woody Wash (Station 248+38) appears to be in good condition (Figure 3). Large cobbles and boulders have been deposited in the upstream channel forcing flood waters along the left wingwall. This has caused some scour along the wingwall that needs to be mitigated by placing riprap and geotextile along the wall and re-aligning the flow in the channel by moving the larger rocks.

Figure 3 Woody Wash Box Culverts Upstream Face

C. 8’ x 6’ Box Culvert

The 8’x6’ concrete box culvert at station 326+13 appears to be in good condition (see Figure 4).

If left in place, riprap and geotextile will need to be placed at the downstream end of the apron.

Figure 4 8’ x 6’ Box Culvert-Upstream Face

The triple 10’x10’concrete box culverts at Landon Spring (station 369+30)appear to be in good condition. Riprap and geotextile, extending 4’ from the outlet apron, is recommended to protect against erosion. (see Figure 5). Update: due to environmental concerns regarding the wetland immediately downstream of the culvert apron, no riprap will be placed at this culvert. This decision should not adversely affect the apron or cutoff wall in the future as the area appears to be stable.

Figure 5 Triple 10’ x 10’ Box Culverts, Landon Springs – Scour at downstream apron

D. Double 6 x 6 Concrete Box Culvert

The double 6’x6’ concrete box culvert at station 431+78 appears to be in good condition. Any extension of this culvert to accommodate the new road width will need to be made on the upstream end due to a concrete block wall located approximately 20’ from the downstream end that is protecting a backyard of a nearby house.

IV. Summary of Recommendations

Culverts needing further review were complete. Tables 1, 2, and 3 show the final results of all culvert analysis.

All major culverts will be kept and repaired or extended as needed

All 18 inch cross-culverts should be replaced with 24 inch culverts. According to the design criteria in the PDDM, the minimum recommended cross-culvert size is 24 inch

End sections will be included on all replacements without headwalls

Riprap aprons with geotextile filter will be placed at all culverts

References:

Aquaveo (2010) Watershed Modeling System Version 9.0 (www.aquaveo.com)

Arizona DOT Drainage Design Manual Hydrology, March 1993.

Federal Highway Administration HY-8, version 8.7.2 (January2012) & version 8.7.3 (July 2012)

Federal Highway Administration (2008) “Project Development and Design Manual” Federal

Lands Highway Division. US Department of Transportation. Chapter 7.

Kimley Horn and Associates, Inc., (April 2007) Drainage Concept Report, ST 89A, Vista

Overlook JW Powell Blvd, Prescott-Flagstaff Highway”, prepared for the Arizona Department of

Transportation, Phoenix, AZ.

National Weather Service NOAA Atlas 14 Precipitation Frequency Data Server.

Trip Report, April 15–18, 2013, Michael Smith, Central Federal Lands Highway Design http://www.aquaveo.com/

APPENDIX A

Hydrology

Culvert Spreadsheet – ADOT Time of Concentration for Drainage Areas < 160 acres

Project: Vista Overlook Date: 5/23/2013

User Input Data

By: V.Ghelardi

Orange Rows- Do not Use Rational Method

Checked:

Design

(yr): 25

(1) Maximum length = 300 ft

(2) Rational method applicable up to 160 acres for Arizona

(3) Source: HDS-2 Table 2.1

(4) HDS-2 equation 2.6

(5) Source: HDS-2 Table 2.2

(6) HDS-2 equation 2.7

(7) HDS-2 equation 2.8

CFL Culvert #

Design

Point

CFL

Station

Pipe

Length (ft) Area (2)

Rational

C

Max

Stream

Slope

Manning's n (3) Slope Kb tt (4) Tc (8) Tc I Q

(ac) (ft/ft) (ft) (mi) (ft/mi) (min) (min) (h) (in/h) (ft3/s)

1 culvert 15+68.81 82 13 0.23 0.0347 1589.0 0.301 183 0.2 19 19 0.317 4.02 12

2 culvert 25+34.95 64 9 0.23 0.0266 1235.0 0.234 140 0.2 18 18 0.3 4.11 9

3 culvert 31+31.46 59 0.34 0.23 0.0060 262.0 0.050 32 0.2 12 12 0.2 4.90 0.38

4 culvert 44+27 38 114 0.23 0.0215 5296.0 1.003 114 0.2 51 51 0.8 2.19 57

5 culvert 50+82.41 49 13 0.23 0.0174 4149.0 0.786 92 0.2 47 47 0.8 2.34 7

6 culvert 55+32.71 47 23 0.23 0.0227 3193.0 0.605 120 0.2 35 35 0.6 2.77 15

7 culvert 61+60.74 54 15 0.23 0.0427 3420.0 0.648 225 0.2 29 29 0.5 3.07 11

8 culvert 72+82.92 43 19 0.23 0.0387 3745.0 0.709 204 0.2 32 32 0.5 2.90 13

9 culvert 77+84.40 68 94 0.23 0.0455 4018.0 0.761 240 0.2 31 31 0.5 2.93 63

10 culvert 89+79.51 47 6 0.23 0.0061 2904.0 0.550 32 0.2 59 59 1.0 1.88 3

11 culvert 93+37.62 47 70 0.23 0.0030 4822.0 0.913 16 0.2 117 117 2.0 1.07 17

12 culvert 96+29.68 120 20 0.23 0.0512 4535.0 0.859 270 0.2 32 32 0.5 2.89 13

13 culvert 104+80.14 44 41 0.23 0.0464 3648.0 0.691 245 0.2 29 29 0.5 3.05 29

14 culvert 117+21.49 44 8 0.23 0.0701 2803.0 0.531 370 0.2 21 21 0.3 3.87 7

15 culvert 122+73.34 61 13 0.23 0.0279 2704.0 0.512 147 0.2 30 30 0.5 3.01 9

16 culvert 132+70.49 16414 0.23 0.2 10 0.2 5.34

17 culvert 142+69.04 42 43 0.23 0.0097 3998.0 0.757 51 0.2 76 76 1.3 1.62 16

18 culvert 148+73.92 65 8 0.23 0.0098 1782.0 0.338 52 0.2 27 27 0.4 3.28 6

19 culvert 154+93.12 63 91 0.23 0.0368 5569.0 1.055 194 0.2 42 42 0.7 2.54 53

20 culvert 161+67.96 64 5 0.23 0.0041 1747.0 0.331 22 0.2 48 48 0.8 2.30 3

21 culvert 166+28 60 162 0.23 0.0393 4986.0 0.944 208 0.2 38 38 0.6 2.68 100

22 culvert 175+68.39 55 11 0.23 0.0389 1783.0 0.338 205 0.2 20 20 0.3 3.97 10

23 culvert 183+20 36 5 0.23 0.0135 334.0 0.063 71 0.2 11 11 0.2 5.23 6

24 culvert 187+69 45 160 0.23 0.0500 2083.0 0.395 264 0.2 20 20 0.3 3.97 146

25 culvert 208+23.74 36 3 0.23 0.0255 457.0 0.087 135 0.2 10 10 0.2 5.32 4

26 culvert 218+91.54 42 7 0.23 0.0156 590.0 0.112 82 0.2 14 14 0.2 4.55 7

26.5 culvert 76 0.23 0.0006 4900.0 0.928 3 0.2 240 240 4.0 0.62 11

27 culvert 224+18.43 39 8 0.23 0.0036 376.0 0.071 19 0.2 19 19 0.3 4.06 7

28 culvert 226+73.46 37 4 0.23 0.0141 975.0 0.185 74 0.2 20 20 0.3 3.94 4

29 culvert 231+00.59 39 128 0.23 0.0017 5472.0 1.036 9 0.2 167 167 2.8 0.78 23

30 culvert 235+27.18 38 66 0.23 0.0184 5797.0 1.098 97 0.2 59 59 1.0 1.87 28

31 culvert 238+51 50 18 0.23 0.0375 2070.0 0.392 198 0.2 22 22 0.4 3.76 16

32 culvert 248+37.47 43 1965 0.23 0.2 10 0.2 5.34

33 culvert 255+10.23 50 8 0.23 0.0533 1874.0 0.355 281 0.2 18 18 0.3 4.12 8

34 culvert 263+01.82 58 12 0.23 0.0448 1803.0 0.341 237 0.2 19 19 0.3 4.05 11

35 culvert 267+02.13 36 4 0.23 0.0186 1810.0 0.343 98 0.2 27 27 0.4 3.31 3

36 culvert 284+99.82 34 20 0.23 0.0303 2872.0 0.544 160 0.2 30 30 0.5 2.99 14

37 culvert 292+98.13 37 5 0.23 0.0251 2126.0 0.403 133 0.2 26 26 0.4 3.35 4

38 culvert 308+73.50 41 82 0.23 0.0360 2880.0 0.545 190 0.2 28 28 0.5 3.20 60

39 culvert 323+33.60 72 2 0.23 0.0454 527.0 0.100 240 0.2 9 10 0.2 5.34 2

40 culvert 326+12.49 527 0.23 0.2 10 0.2 5.34 110

41 culvert 329+25.55 37 106 0.23 0.0319 4866.0 0.922 168 0.2 40 40 0.7 2.58 63

42 culvert 346+13.46 84 2 0.23 0.0196 368.0 0.070 103 0.2 10 10 0.2 5.34 2

43 culvert 352+07.14 82 7 0.23 0.0209 1739.0 0.329 110 0.2 25 25 0.4 3.49 6

44 culvert 357+06.84 44 7 0.23 0.0526 2052.0 0.389 278 0.2 19 19 0.3 4.02 6

45 culvert 361+56 63 1 0.23 0.0807 599.0 0.113 426 0.2 8 10 0.2 5.34 1

46 culvert 365+59 82 40 0.23 0.0318 3424.0 0.648 168 0.2 33 33 0.5 2.88 27

47 culvert 369+51.43 105 2590 0.23 0.2 10 0.2 5.34 840

48 culvert 378+25.21 2 0.23 0.0280 464.0 0.088 148 0.2 10 10 0.2 5.34 2

49 culvert 390+68 74 20 0.23 0.0404 1963.0 0.372 213 0.2 20 20 0.3 3.88 18

50 culvert 399+62 43 132 0.23 0.0204 4718.0 0.894 108 0.2 48 48 0.8 2.30 70

51 culvert 406+65 35 6 0.23 0.0121 1537.0 0.291 64 0.2 29 29 0.5 3.11 4

52 culvert 414+97 32 23 0.23 0.0032 2056.0 0.389 17 0.2 61 61 1.0 1.82 10

53 culvert 431+78 59 325 0.23 0.2 10 0.2 5.34 190

54 culvert 444+46 76 175 0.23 0.2 10 0.2 5.34 50

Length (1)

(8) Minimum Tc is 10 minutes for AZ

44+27

166+28

Culvert 183+20

Culvert 187+69

238+51

Flow line arrows

361+56

Retention Pond

Culvert

444+46 Flow lines going east to west

APPENDIX B

Hydraulic Analysis

Station 15+72

Station 25+62

Station 44+24

Station 50+78

Station 55+29

Station 60+57

Station 72+58

Station 77+80

Station 89+76

Station 93+34

Station 96+26

Station 104+76

Station 117+12

Station 122+69

Station 132+72

Station 142+73

Station 148+73

Station 154+90

Station 161+72

Station 166+32

Station 175+60

Station 183+24

Station 187+48

Station 208+11

Station 218+96

Station 224+32

Station 226+73

Station 230+82

Station 235+32

Station 238+43

Station 248+38

Station 255+18

Station 263+10

Station 285+08

Station 293+07

Station 308+70

Station 326+12

Station 346+11

Station 352+51

Station 357+31

Station 365+56

Station 369+30

Station 399+52

Station 406+55

Station 414+87

Station 431+69

Station 444+10