ID_PFH21(7)_HydraulicsReport_all_FINAL.pdf

Memorandum

Western Federal Lands Highway Division 610 E. Fifth Street

Vancouver, WA 98661-3801

HYDRAULICS REPORT

FINAL

To: Dan Slanina, WFLHD Project Manager From: Carolyn Sourek, WFLHD Hydraulics Engineer Date: January 22, 2018 Project: Warren Wagon Road – ID PFH 21(7)

Project Description

Valley County is constructing improvements to 5.5 miles of the Warren Wagon Road, an important recreation route into the Payette National Forest near McCall, Idaho. A project map is provided as Figure 1 in the attachments. The County will maintain the road and drainage structures. Western Federal Lands Highway Division (WFLHD) is designing the road improvements per Federal Highways Administration (FHWA) guidance. The road improvements include approximately 5.5 miles of 11 foot wide lanes with three foot shoulders and some four foot shoulders, roadway reconstruction, minor surface water drainage corrections, East Side Drive intersection reconfiguration, and two aquatic organism passage (AOP) culverts.

Rock scaling is also proposed on the project.

This report provides recommendations based on the Final Design for drainage structures, both minor and major. Design recommendations are based upon guidance from the Federal Lands Highway (FLH) Project Development and Design Manual (PDDM), visual analysis of the site, and constructability.

Recommendations

Clean and reestablish ditch grade upstream and downstream of existing and proposed culverts.

For culverts subjected to rockfall, provide inlet protection.

Realign where established trees are obstructing inlet or outlet.

Comply with Chapter 7 of the Project Design and Development Manual (PDDM) and the WFLHD Chapter 7 Supplemental for designing the drainage structures.

Clean debris from culvert inlets and interiors.

Replace undersized, damaged, or clogged culverts that cannot be cleaned.

Verify that drainage culverts have minimum pipe cover.

Use aluminum or aluminized-steel pipe where rusting has been a problem. Minimum wall thickness

To: Dan Slanina, Project Manager WFLHD 2 January 22, 2018 for galvanized-steel or aluminum pipe should be 0.0625 inches. Thicker pipe may be needed to meet structural criteria.

Minimum size of ditch-relief culverts should be 24 inches or replaced in kind with adequate capacity checked.

Install ditch-relief culverts at 0.5 percent for promoting cleaning flow velocities.

Reduce potential for sediment clogging cross-drain culverts by installing them on the average channel gradient. Follow the PDDM, Chapter 7.3.6.3 Design Guidance, for assessing and mitigating culvert abrasion.

Control erosion at the outlets by installing riprap splash pads, riprap-lined chutes, or down drain pipes. Chutes should have a well-defined flow line and channel shape at least 12- inches deep.

Culvert spacing should not exceed 500 feet. Smaller culvert spacing may be needed for erosion control and to increase capacity of ditches.

Evaluate existing ditch slopes for erosion potential. Line existing and proposed ditches at slopes with observed erosion potential with riprap for controlling erosion.

Re-stabilize embankments by lengthening culvert and/or making a larger headwall to support embankment.

Culvert Inventory

A culvert assessment was conducted by members of Design and Hydraulics in July 2015. The FLH Culvert Assessment and Decision-Making Procedures Manual was consulted and assessment tools within utilized.

Culverts were evaluated visually for invert deterioration, joint and seam stability, corrosion or chemical deterioration, cross-sectional deformation, cracking, liner or wall deterioration, mortar and masonry integrity, rot and marine borers, headwall and wingwall stability, apron integrity, flared end section soundness, pipe end capacity, and any scour protection integrity. Only applicable elements were evaluated.

Specific performance related issues were noted, which include debris, vegetation, or sediment blockages at inlet, outlet, or throughout the culvert length, poor channel alignment, buoyancy or crushing-related inlet failures, overtopping issues, local outlet scour, channel degradation or headcutting, embankment slope instability, or embankment piping.

A total of 46 culverts were evaluated as part of the assessment. Photos of each culvert were taken and culvert assessment form completed. These are not included in this report, but are available on request.

Hydrology

High standard roadways are classified as such if design speed is greater than 45 mph, average daily traffic (ADT) is greater than 1500, or is designated as a critical access road. Design ADT is 1900 for year 2030, so this roadway is classified as high standard. High standard roadway culverts have a design flood equivalent to the 50 year recurrence interval. Peak streamflow estimates were generated using the United States Geological Service (USGS) Report WRIR 02-4170 (2002).

To: Dan Slanina, Project Manager WFLHD 3

Actual contributing drainage area was compared to allowable contributing drainage area given an existing culvert set of characteristics. Actual contributing drainage area was generated using the USGS StreamStats

4.0 online tool. Drainage areas which were too small to trigger a drainage area for StreamStats were estimate using contour topography from survey and terrain modelling in Google Earth Pro. Allowable drainage area was back calculated for existing culverts using equation A.2 from Hydraulic Design Series 5 (HDS 5) and assuming headwater to diameter ratio of 1.2 per PDDM requirements for culverts under 48 inches diameter. If the allowable drainage area was greater than actual drainage area the culvert was deemed adequately sized for the existing condition. StreamStats output reports are not included in this report but area available upon request. The regression calculation spreadsheet is provided as an attachment.

Hydraulics

Further visual and design assessment was completed by members of Design in 2016 and 2017. The original recommendations based on the 2015 assessment have been modified to incorporate addition design efforts and observations. Updated recommendations retain adequate hydraulic performance and capacity.

Existing culverts have been evaluated for performance and condition as well as capacity. Those that exhibited significant performance issues or were of deteriorating condition are recommended to be replaced. Those that have insufficient capacity are also recommended to be replaced. Culverts were also identified that required cleaning. Table 1 provides a summary of culverts requiring cleaning, replacement, or miscellaneous repairs.

cc: Sven Leon, WFLHD Senior Hydraulics Engineer Clinton Choy, WFLHD Design Erin Chipps, WFLHD Environment Jim Rathke, WFLHD Construction attachments: Table 1 – Culvert Recommendations Summary Table

Figure 1 – Project Map Regression Analysis Calculation Spreadsheet

Table 1.

Culvert Recommendations

Existing Recommended Condition and Performance Comments/Observations

Station Action Size (in)

Material Size (in)

Material

312+54 C 18 CMP ‐ ‐

Clean, Grade ditch to drain, no apparent outfall, poor outfall grade, sediment blockage 1/3 to 3/4 at outlet

312+77 C 18 CMP ‐ ‐ Clean sidewalk cross culvert

314+04 C 18 CMP ‐ ‐

Clean approach culvert for Green Gate Snow Park

322+00 C 18 CMP ‐ ‐

Clean, debris/vegetation blockage >1/3 at outlet

331+34 N 18 CMP

Road cross culvert to drain left ditch between road and sidewalk, capacity adequate

332+18 C 18 CMP ‐ ‐ Clean sidewalk cross culvert

332+25 R 18 CMP 18 CMP Replace in kind, capacity adequate

340+84 R 18 CMP 24 CMP

Replace with 24 in, Grade ditch to drain, clean culvert, sediment blockage 1/3 to 3/4 at inlet, sediment blockage > 1/3 throughout barrel

342+25 R 24 CMP 24 CMP

Replace, Grade to drain, under path and roadway, minor bank erosion, corrosion at outfall, possible piping, inlet end section disconnected from culvert, poor channel alignment, 352+53 C 18 CMP ‐ ‐ Clean

357+97 R 15 CMP 15 CMP Replace in kind, reset inlet

358+53 C 18 CMP Clean culvert, remove inlet

359+52 C 18 CMP 24 CMP

Clean, embankment stable at outlet, field sediment blockage 1/3 to 3/4 at inlet

360+86 R 52 CMP 144 CMP

Replace as AOP, 1 ft drop at outlet, water main/water pump throughout stream, AOP, local outlet scour, To: Dan Slanina, Project Manager WFLHD 5

Comments/Observations

Station Action Size (in)

Material Size (in)

Material

363+55 X 18 CMP ‐ ‐

Remove per public request and project management directive

369+27 C 18 CMP ‐ ‐

Clean, Grade ditch to drain, Stabilize embankment or extend pipe, embankment stability issues at outlet, sediment blockage 1/3 to 3/4 at inlet

370+64 N ‐ ‐ 12 CMP

New approach culvert, sized to maximum capacity and fit field conditions

375+58 R 18 CMP 132 CMP

Replace as AOP inlet very vegetated, 6" drop at outlet, AOP local outlet scour

377+92 O 54 CMP ‐ ‐

Flowing adequately, avoid impacting, driveway impacts and bank instability

381+40 C 18 CMP ‐ ‐ Clean

385+41 C 18 CMP ‐ ‐

Clean; Grade ditch to drain; Extend outlet or stabilize embankment no apparent outfall, poor outfall grade, embankment sloughing into outlet sediment blockage 1/3 to 3/4 at outlet

393+01 R 18 CMP 18 CMP

Replace in kind, verify/avoid utilities and property impacts, adequate capacity

393+58 N ‐ ‐ 12 CMP

New approach culvert, sized to maximum capacity and fit field conditions

399+47 R 18 CMP 18 CMP

Replace in kind, grade ditch to drain, poor outfall grade, sediment blockage at outlet, rockfall area, protect inlet ‐ concrete headwall, sediment at inlet, capacity adequate

401+95 R 18 CMP 18 CMP

Replace in kind, grade ditch to drain, inlet rockfall damage ‐ concrete headwall, capacity adequate

To: Dan Slanina, Project Manager WFLHD 6

Comments/Observations

Station Action Size (in)

Material Size (in)

Material

407+89 R 18 CMP 18 CMP

Replace in kind, grade ditch to drain, poor outfall grade, sediment blockage at outlet, rockfall area, protect inlet ‐ conc headwall, sediment at inlet, capacity adequate

413+47 R 18 CMP 18 CMP

Replace in kind, inlet damage and liner degradation, lengthen culvert, rockfall area, concrete headwall, capacity adequate

418+45 R 18 CMP 24 CMP

Replace, rockfall damage, remove tree, extend at inlet, sediment blockage 1/3 to 3/ at inlet

428+14 C 18 CMP ‐ ‐ Clean

438+12 C 18 CMP ‐ ‐

Clean, grade ditch to drain, rockfall area, concrete headwall

446+59 C 18 CMP ‐ ‐

Clean, grade ditch to drain, rockfall area, concrete headwall

450+50 C Unk Unknown Clean

463+50 C Unk Unknown Clean

468+92 N ‐ ‐ 6 CMP

New approach culvert, sized to maximum capacity and fit field conditions

470+44 N ‐ ‐ 6 CMP

New approach culvert, sized to maximum capacity and fit field conditions

474+33 C 18 CMP ‐ ‐

Clean, grade ditch to drain, rockfall area, concrete headwall

476+46 C Unk Unknown ‐ ‐ Clean

480+96 C 18 CMP ‐ ‐ Clean approach culvert

482+10 C 18 CMP ‐ ‐ Clean approach culvert

482+41 R 18 CMP 18 CMP Replace in kind, capacity adequate

486+96 O 18 CMP ‐ ‐

Flowing adequately, avoid impacting

494+59 R 18 CMP 24 CMP Replace, grade ditch to drain, To: Dan Slanina, Project Manager WFLHD 7

Comments/Observations

Station Action Size (in)

Material Size (in)

Material rockfall damage ‐ concrete headwall, lengthen

501+59 R 18 CMP 18 CMP

Replace in kind, grade ditch to drain, rockfall damage ‐ concrete headwall, lengthen, capacity adequate

506+79 R 18 CMP 18 CMP

Replace in kind, rockfall damage at inlet and outlet, riprap headwall, grade ditch to drain, buoyancy or crushing inlet failure, capcity adequate

511+48 R 18 CMP 18 CMP

Replace in kind, grade ditch to drain, rockfall damage ‐ concrete headwall, lengthen, capacity adequate

515+50 N ‐ ‐ 18 CMP

New road cross culvert to drain left ditch

518+19 X 18 CMP ‐ ‐

Remove, existing culvert does not drain with proposed ditch profile

523+74 R 24 CMP 24 CMP

Replace, existing culvert does not drain with proposed ditch profile

533+72 R 18 CMP 18 CMP

Replace in kind, grade ditch to drain, major sediment blockage at inlet, pavement failure above, need to extend inlet sediment blockage 1/3 to 3/4 at inlet sediment blockage >3/4 at inlet, capacity adequate

539+86 N ‐ ‐ 24 CMP New roadway cross culvert

556+44 R 18 CMP 18 CMP

Replace in kind, grade ditch to drain, capacity adequate

561+88 R 18 CMP 18 CMP

Replace in kind, outlet damaged, capacity adequate

565+17 R 48 CMP

equiv

CMP

Replace, clear vegetation at inlet and outlet, grade ditch to drain, fix outlet scour

566+75 R 18 CMP 18 CMP Replace in kind, capacity adequate

567+71 O 36 CMP ‐ ‐

Flowing adequately, avoid impacting

To: Dan Slanina, Project Manager WFLHD 8

Comments/Observations

Station Action Size (in)

Material Size (in)

Material

570+71 R 18 CMP 18 arch Replace in kind, grade ditch to drain, capacity adequate

573+47 C 18 CMP ‐ ‐ Clean ditch and culvert

580+65 C 18 CMP ‐ ‐

Clean, debris/vegetation blockage >1/3 at inlet

589+72 C 18 CMP ‐ ‐

Clean, grade ditch to drain, debris/vegetation blockage > 1/3 at outlet

Notes:

R = Replace

CMP = Corrugated Round Metal Pipe

C = Clean Arch = Corrugated Arch Metal Pipe N = New O = Other Repair

X = Remove

FIGURE 1

PROJECT MAP – ID PFH 21(7)

WARREN WAGON ROAD

Proposed Alignment

Project Site 0 1 mile

N

Start Project

MP 2.2

End Project

MP 9.6

Payette Lake

Valley County

Adams County McCall

End Pave Start Overlay

MP 7.6

Park Boundary

County Boundary

Payette National Forest

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FLOOD DISCHARGE ESTIMATES

UNGAGED IDAHO SITES

Project: File:

Desc: By:

Region: 5 Date:

Exceed Coefficients Equation:Q = a(A^b)*(P^c)*(NF30+1)^d

Prob. a b c d Error Source:

0.50 0.0297 0.995 2.200 -0.664 39.80%

0.10 0.1780 0.957 1.790 -0.571 38.50% USGS Report - WRIR 02-4170

0.04 0.3190 0.943 1.660 -0.538 39.20% Culvert Type HW/D K M a

0.02 0.4560 0.934 1.580 -0.517 40.00% Major CMP-EndTr 0.7 0.021 1.33 13.964

0.01 0.6200 0.926 1.520 -0.499 41.10% General CMP - Proj 0.7 0.034 1.5 7.512

Drain. Mean % North Estimated Discharge (Q) Min.

Area, Annual Face Slope Exceedance Probability 0.02 Culvert

Station A Precip, P > 30%, NF30 0.50 0.10 0.04 0.02 0.01 Design Dia

(sq mi) (in) (%) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) (ft)

Minimum 3.6 19.8 2.5

Maximum 12228 49.73 32.9

2.02 35.0 0 149 203 226 242 264 242 3.4

2.02 32.1 0 123 173 196 211 232 211 3.3

0.37 30.6 0 20 31 37 40 45 40 1.7

2.63 38.7 3 96 141 163 177 197 177 3.0

General 0.12 35 0 9 14 16 17 19 17 1.5

0.25 35 0 19 27 32 34 38 34 2.0

0.45 35 0 33 48 55 60 66 60 2.5

0.74 35 0 55 77 88 95 104 95 3.0

1.10 35 0 81 113 128 137 151 137 3.5

Notes:

a = ((HW/D)/K)^(1/M)

K = Constant from Table A.1, HDS‐5 (2012)

M = Constant from Table A.1, HDS‐5 (2012)

D = [Q/(0.7844x(1/K^1/M))]^.4 from HDS‐5, equation A.2. Assumes HW/D < 1.2 ,unsubmerged.

Sylvan Ck

Estimating the Magnitude of Peak Flows at Selected Recurrence Intervals for Streams in Idaho, 2002

Copet Creek

5/3/2016

Wagon Bay Ck

Sta 566+36

Warren Wagon Road - ID PFH 2(17) IDPFH217_Regression Analysis.xlsx

Major Drainage Peak Flow C. Sourek