AK UnnamedTrib AOP Report Final.pdf

Memorandum Western Federal Lands Highway Division

610 E. Fifth Street Vancouver, WA 98661-3801

SWAN LAKE / SWANSON RIVER ROAD

UNNAMED TRIBUTARY AOP HYDRAULICS REPORT

To: Stacy Bluhm, WFLHD Project Manager

From: James Neighorn, P.E. and Vernon Bevan, WFLHD Hydraulics Engineer

Date: June 20, 2023

Project: Swan Lake / Swanson River Road – AK FWS Kenai 74525(1)

Background

The Kenai National Wildlife Refuge (NWR) is rehabilitating Swan Lake Road and Swanson River Road to improve access to public recreation along the corridors, increase transportation safety, and to mitigate damage to wildlife and aquatic organism passage. As part of the project the NWR is replacing a culvert located on Swan Lake Road where it crosses an unnamed tributary downstream of Cashka Lake, Kenai

National Wildlife Refuge, Kenai Peninsula Borough, Alaska. Western Federal Lands Highway Division

(WFLHD) is designing the replacement structure. The Kenai NWR will maintain the new structure.

Recommendations for the proposed aquatic organism passage (AOP) structure design are presented.

AOP Design Criteria

The proposed AOP structure has been designed following the requirements Culvert Design Guidelines for

Ecological Function (U.S. Fish and Wildlife 2021) and per Stream Simulation: An Ecological Approach to

Providing Passage for Aquatic Organisms at Road-Stream Crossings (USDA-Forest Service 2008). These documents provide simplified design methodologies intended to mimic natural stream processes within the culvert. Sediment transport, debris conveyance and streambed morphology within the culvert should replicate these processes as they occur in the natural channel upstream and downstream of the culvert.

Determination of the high and low fish passage design flows, water velocity, and water depth is not required for this method since the stream hydraulic characteristics within the culvert are intended to replicate the stream conditions upstream and downstream of the crossing. AOP culvert design utilizes streambed materials and sizes which occur in the natural channel, providing similar channel complexity, flow depth, flow velocities, and resting areas.

USFW Alaska Fish Passage Program (USFW/AFPP) Guidelines

The AOP design for the unnamed tributary outfall crossing is consistent with the 2021 U.S. Fish and

Wildlife (USFW) Service design guidelines. The 2021 document generally follows the U.S. Forest Service stream simulation approach with certain modifications. The basis for AOP design is the geomorphic analog method. The underlying philosophy of the geomorphic analog method is similar to the stream simulation approach. However, many of the design criteria are based on the 100-year flood event as opposed to a specifically selected design flood. The following USFW/AFPP requirements have been incorporated into the AOP design:

Flood and Debris Conveyance: Culvert capacity is designed to accommodate the 100-year recurrence flood without interfering with the functioning of the floodplain while providing adequate clearance above the flood stage for expected debris. The headwater depth to opening depth ratio should be less than 0.8.

Crossing Location: Crossing structure is placed within the pre-development natural channel alignment

Memo to: Stacy Bluhm, WFLHD Project Manager

June 2023 wherever possible.

Culvert Width: Must accommodate the design channel bankfull width plus additional width for construction of stable bank rocks along both sides of the channel inside the culvert. All culverts will meet design requirements for a 6-foot minimum diameter.

Channel Vertical Clearance: Clearance from bed to ceiling must be at least 4-feet to allow for ease of construction, maintenance, and debris removal. Where possible, clearance will be 5-feet or greater.

Channel Slope: Reconstructed streambed within the culvert approximates the average slope of the stream reference reach. The slope should not deviate by more than 25% from the natural stream slope of the reference reach.

Embedment: Bottoms of round culverts should be buried below the streambed thalweg a minimum of

40% of the pipe diameter. Box or pipe arch culverts should be buried a minimum of 20% of the culvert’s rise.

Maximum Length of Road Crossing: Length should be less than 150-feet.

Fill Materials: Fill materials are generally comprised of sediment similar in size composition to natural bed materials that form the natural stream channel above and below the road crossing. Larger material is added to assist grade retention and provide resting areas for migrating fish. A dense, well-graded mixture is specified, with washing in of fines between constructed lifts, to encourage the stream to flow on the surface.

Fill/substrate material for culverts without an adequate sediment supply, such as those situated below a lake or wetland, should be designed to resist the predicted critical shear forces of the 100-year flood.

Water Depth and Velocity: Bankfull water depths and velocities in the culvert must closely resemble those existing reference reach as specified in the 2021 USFW Service guidance document.

Unnamed Tributary AOP Culvert

United States Fish and Wildlife Service (USFWS) has determined that an unnamed tributary crossing Swan

Lake Road downstream of Cashka Lake requires an AOP structure (60°44'12.77"N, 150°47'36.35"W

NAD1983). Federal Lands Highway Division conducted field reconnaissance of the crossing in 2019 and

2021.

The crossing is located on an unnamed tributary, approximately 0.4-miles upstream of its confluence with the Swanson River and roughly 0.6 miles downstream of Cashka Lake (Figure 1). The unnamed tributary crosses Swan Lake Road through a primary 36-inch diameter CMP set in the channel and a secondary 36-inch diameter CMP flood relief pipe set at the floodplain elevation (Photos 1 and 4). The upstream reach is a highly sinuous, single thread channel meandering through a wide, low gradient valley with a slope of roughly 1.5% (Photo 5). The upstream reach appears to be very stable, with well vegetated banks and coarse bed material. Riffle-pool is the dominant bedform and the channel gradient is controlled by the riffle crests.

The bankfull channel was observed to be roughly 2.5 to 3-feet wide and 1.5 to 2.5-feet deep (Photo 6).

Immediately downstream of the culvert outfall, the stream lacked the well-defined features of a mature channel (Photo 7) with a slope approaching 2%. Approximately 100 feet downstream, there is a small vertical headcut indicating that the channel is in a dynamic state (Photo 8). Further downstream the stream evolves into a more defined and stable channel cross-section and the streambed material becomes courser

(Photo 9) with a slope of approximately 2.4%. At this point the channel assumes a riffle-pool form with well vegetated banks. Channel bankfull widths measured between 3 and 4 feet and bankfull depth ranged from 2 to 2.5 feet. Due to the small size of the channel, the stream has little capacity to transport woody debris.

Pebble counts were performed upstream and downstream and downstream of the cross. The FHWA

Hydraulic Toolbox, version 4.2, was used to compute the gradation of the individual and combined pebble count data. The combined gradation was: D100 10-inches, D85 2.1-inches, D50 0.8-inches, and D15 0.14-inches (Figure 3).

The existing crossing is currently served by a primary 36-inch CMP and a flood relief 36-inch CMP (Photo

2 and 3). The roadway elevation provides adequate cover over the existing culvert. Evidence of extensive scour at the culvert outfall was not observed and both culverts were free of woody debris. Existing culverts are situated perpendicular to the roadway and well aligned with the stream thalweg.

Recommendations:

A larger pipe will be necessary to replace the two existing 36-inch culverts as well as provide space for bankfull width, a natural channel bottom, and stable banks.

• Install an 84-foot long, corrugated metal round culvert with a 9-foot diameter.

• Skew the new culvert to better align with the existing stream channel on the upstream side of the road.

• Place the culvert at a 1.96% slope to match the average channel slopes at the crossing by setting the inverts at elevation 186.18-feet upstream and at elevation 184.54-feet downstream (project datum).

• Embed the culvert a minimum of 3.8 feet and backfill the culvert interior with streambed material conserved during excavation of the culvert. If the conserved streambed material quantity is insufficient for backfilling the culvert, use material similar to the natural streambed material.

Streambed material will be augmented with Class C gradation cobbles specified in the attached

Special Contract Requirements (SCR) and Gradation Stability Calculations to provide a dynamically stable substrate.

• Allow clearance for debris passage and maintenance access by providing 5.2 feet of clearance from the crown of the culvert and the installed bed material. The headwater to depth of opening ratio

(HW/D) provided is 0.82 which outside the targeted 0.80 for debris clearance by 2%. Since the channel width is 3 feet with little ability to transport significant sized debris, the clearance provided is not expected to result in plugging issues.

• Construct a channel with a bankfull width of 3 feet and a bankfull depth of 1.5 feet including a low flow channel and streambanks inside the culvert to provide resting opportunities for fish.

• Install 7 rock weirs spaced at 12-foot intervals to help maintain banks and channel shape.

• Install 7 round boulders, approximately 24-inches in diameter for inducing channel migration and providing low velocity fish resting areas.

• Install concrete collars to mitigate the influence of frost heaving at pipe ends.

• Install Class 3 riprap (FHWA FP-14), minimum 3 feet thick, at the inlet and outlet for controlling erosion near the culvert.

• Install a 36-inch diameter flood relief culvert to reduce flow velocities and increase debris clearance during larger flows.

Construction

The Alaska Department of Fish and Wildlife instream work period is May 15 to July 15. Temporary flow deflectors placed for isolating the work area and diverting the stream flow must have a minimum height of

3-feet above the stream bottom and be stable assuming 6-feet per second parallel flow. Use plastic-lined channels or pipes for temporally conveying stream flow through the construction area. Protect the outfalls from erosion. Ensure fish can pass smoothly through the diversion. Temporary stream diversions in place must provide an equivalent capacity to a 2.5-foot diameter pipe or demonstrate a minimum flow capacity equal to the 2-year discharge (46-cfs). Before installing the flow deflectors, remove fish from the work area to the level and methods meeting the 2009 ADF&G and FHWA Fish Habitat MOU requirements.

Full construction area dewatering is expected up to the groundwater level for excavation and installing the culvert, streambed material, backfill, and riprap. Water pumped from work area must be discharged at an upland treatment area near the site.

Temporary access route adjacent to the road embankment is needed for installing flow barriers, removing the channel debris, and completing culvert inlet, interior, and outlet work.

Stream Impacts

The proposed fish passage culvert is expected to dramatically improve stream flow conveyance, sediment transport, and woody debris transport to a level comparable to reaches upstream and downstream of the culvert. A moderate amount of turbidity and sediment is expected to be released when the flow barriers are removed, and stream flow is introduced into the newly constructed culvert. The amount of turbidity and sediment will be reduced by removing the flow barriers gradually introducing the stream flow over an extended two to three-hour time.

Operation and Maintenance

Scour or aggradation of the streambed is also expected to occur to some extent, as would be expected for the natural stream. Monitoring at regular intervals, and ideally during flood events, will be especially important during the first few years to ensure that excessive debris accumulation, scour, or aggradation does not impair passage through the culvert. Increase the frequency of culvert inspections and debris removal for the first three years. Fish boulders placed within the culvert and stream channel should be inspected annually and after each extreme flood event to ensure effective backwater and bed retention.

Replace or reposition dislodged rock or boulders. Additional rock may need to be installed to correct erosion or channel degradation. Riprap placed at the culvert inlet and outlet should be inspected annually and after each extreme flood event. Replace or reposition dislodged stone.

Floodplain and Flood-rise Impacts

Flood limits and elevations have not been mapped by the National Flood Insurance Program for the site.

The proposed culverts will improve hydraulic conveyance and is not expected to negatively impact flooding at the site.

Hydrology

The USGS StreamStats (version 4) web-based application was used for delineating the watershed and calculating drainage area (3.2 sq. miles) and mean annual precipitation (17-inches). Since delineations made by StreamStats can include inaccuracies for smaller watersheds and flat areas, the delineated watershed was verified by comparing it to both USGS TOPO maps and Digital Terrain Maps produced by the Alaska

Division of Geological and Geophysical Surveys. No significant deviations that would impact flow estimates were found.

Peak discharges were estimated with StreamStats using USGS regression equations from Magnitude and

Frequency at Gaged and Ungaged Sites on Streams in Alaska and Conterminous Basins in Canada (USGS

WRIR 2016-5024). The watershed is mostly comprised of forested land and surface water (Figure 2).

Dozens of lakes are located within the basin and their presence can influence the amount of runoff generated by the basin. Lakes can increase runoff by increasing the amount of impervious surface area, or conversely, lakes can act to attenuate flows. Hydraulic modeling of the channel and the existing culverts indicate that the flows derived from the USGS regression equations are likely reasonable estimates of the basin’s hydrology. A summary of peak discharges and their corresponding water depths at the culvert inlet are presented in Table 1.

Dominant flooding is from snow melt. Larger floods typically occur in April and May. Rain-on-snow flood events can occur in October through December. Lower flows typically occur from January to February and

July through September.

Culvert Hydraulics

Water surface profiles and culvert capacities were estimated using the FHWA Culvert Hydraulics Analysis

Program, HY-8, version 7.7 (results attached). Floods larger than the 2-year were analyzed assuming culvert slope of 1.95 percent and Manning’s Roughness coefficient of 0.035 for the channel bottom and 0.024 for the culvert sides and top.

The computed outlet tailwater depth of 1.7 feet for the 2-year discharge was compared with the bankfull channel design depth of 1.5 and found to be within the measured range of the 1.5 to 2.5 feet in the natural channel.

Hydraulic results are included in the attachments with headwater depths and ratios shown in Table 2.

Attachments: Table 1 - Peak Discharge Estimates

Table 2 – Headwater Depths and Ratios

Figures 1, 2, and 3

Photographs

HY-8 Calculations

USGS StreamStats Report

Drawings

Special Contract Requirements and Gradation Stability Calculations

Tables

Table 1. Peak Discharges Estimates Peak Annual Floods Discharge (ft3/2)

2-Year 46 5-Year 84

10-Year 115 25-Year 159 50-Year 194

100-Year 233 200-Year 273 500-Year 330

Table 2. Peak Discharges and Water Depths Peak Annual

Floods Discharge (ft3/2) Headwater Depth (HW)

(ft)

HW/D

(D= 5.2 ft) 2-Year 46 1.60 0.31

50-Year 194 3.79 0.73 100-Year 233 4.28 0.82

D = Distance between culvert crown and streambed

Image date: 4/17/2011

Project AOP Culvert Site Location

Project Area Location

USGS Topographic Maps on Google Earth

N

FIGURE 1

UNNAMED TRIBUTARY

AOP CULVERT

SITE LOCATION

AOP

1000 feet0

Map printed from Google Earth, Image date 4/17/2011.

N

DA = 3.2 sq. mi.

FIGURE 2

UNNAMED TRIBUTARY

AOP CULVERT

DRAINAGE AREA

0 5000 feet

Photos

PHOTO 1

6/5/2019

PHOTO 2

7/27/2021

PHOTO 3

7/27/2021

Swan Lake Road - Unnamed Tributary

Culvert appears to be in good condition.

Culvert was dry duing the site visit and is likely only activated during large events.

Culvert is in fair condition. No warping/sagging observed. Some streambed material within culvert.

Looking through culvert located on adjacent floodplain bench.

Looking downstream at culvert inlets.

Crossing is served by two 36-inch CMPs. The right culvert is set at adjacent floodplain elevation. The left culvert is set within the main channel thalweg.

Looking through culvert located within the main channel.

PHOTO 4

7/27/2021

PHOTO 5

7/27/2021

PHOTO 6

6/5/2019

Swan Lake Road - Unnamed Tributary

Relatively coarse bed material. Bankfull width between 2.5-feet to 3-feet wide.

Bankfull depth between 1.5 to 2.5-feet deep.

Looking upstream at culvert outfalls.

Crossing is served by two 36-inch CMPs. The left culvert is set at adjacent floodplain elevation. The right culvert is set within the main channel thalweg.

Channel upstream of culvert crossing.

Upstream channel meanders through a wide low gradient valley. The upstream channel appeared stable with cobble bottom and thickly vegetated floodplain.

Channel upstream of culvert crossing.

PHOTO 7

7/27/2021

PHOTO 8

7/27/2021

PHOTO 9

6/5/2019

Swan Lake Road - Unnamed Tributary

Channel a few hundred feet downstream of the culvert outfall.

Channel immediately downstream of the culvert outfall lacked defined features of a mature channel.

Further downstream the channel evolves into a more defined, stable channel cross-section. Additionally the channel streambed material becomes more coarse.

Channel downstream of Photo 7 location.

Small vertical headcuts further downstream also indicate that the channel is in a dynamic state.

Channel just downstream of culvert outfall.

HY-8 Culvert Analysis Report - Proposed AOP Crossing Discharge Data Discharge Selection Method: Specify Minimum, Design, and Maximum Flow

Minimum Flow: 46.00 cfs

Design Flow: 194.00 cfs

Maximum Flow: 233.00 cfs

Table 1 - Summary of Culvert Flows at Crossing: Unnamed Tributary Headwater Elevation (ft)

Total Discharge (cfs)

Unnamed Tributary Discharge (cfs)

Flood Relief Discharge (cfs)

Roadway Discharge (cfs)

Iterations

191.58 46.00 45.82 0.17 0.00 4

191.91 64.70 63.36 1.33 0.00 4

192.24 83.40 79.90 3.48 0.00 4

192.54 102.10 96.05 6.21 0.00 6

192.81 120.80 111.46 9.28 0.00 3

193.07 139.50 126.85 12.59 0.00 3

193.32 158.20 142.21 15.97 0.00 3

193.56 176.90 157.49 19.40 0.00 3

193.77 194.00 171.49 22.51 0.00 3

194.02 214.30 188.13 26.17 0.00 3

194.26 233.00 203.50 29.54 0.00 3

200.32 588.48 508.04 80.45 0.00 Overtopping

Rating Curve Plot for Crossing: Unnamed Tributary

Culvert Data: Unnamed Tributary

Table 1 - Culvert Summary Table: Unnamed Tributary 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)

46.00 cfs 45.82 cfs 191.58 1.60 1.554 3- M1t

0.98 0.93 1.75 1.75 2.94 4.06

64.70 cfs 63.36 cfs 191.91 1.92 1.931 3- M1t

1.20 1.16 1.91 1.91 3.73 4.00

83.40 cfs 79.90 cfs 192.24 2.22 2.258 3- M1t

1.39 1.35 2.01 2.01 4.47 4.12

102.10 cfs 96.05 cfs 192.54 2.50 2.556 3- M1t

1.57 1.53 2.09 2.09 5.18 4.25

120.80 cfs 111.46 cfs 192.81 2.76 2.827 3- M1t

1.73 1.68 2.16 2.16 5.82 4.37

139.50 cfs 126.85 cfs 193.07 3.02 3.087 3- M1t

1.88 1.83 2.22 2.22 6.46 4.50

158.20 cfs 142.21 cfs 193.32 3.28 3.337 3- M1t

2.03 1.98 2.28 2.28 7.07 4.61

176.90 cfs 157.49 cfs 193.56 3.53 3.578 3- M1t

2.18 2.11 2.33 2.33 7.67 4.71

194.00 cfs 171.49 cfs 193.77 3.76 3.793 3- M1t

2.31 2.24 2.37 2.37 8.22 4.81

214.30 cfs 188.13 cfs 194.02 4.03 4.044 3- M2t

2.47 2.37 2.41 2.41 8.85 4.91

233.00 cfs 203.50 cfs 194.26 4.28 4.271 2- M2c

2.61 2.50 2.50 2.45 9.27 5.00

Culvert Barrel Data Culvert Barrel Type Straight Culvert

Inlet Elevation (invert): 189.98 ft, Outlet Elevation (invert): 188.34 ft

Culvert Length: 84.02 ft, Culvert Slope: 0.0195

Culvert Performance Curve Plot: Unnamed Tributary

Site Data - Unnamed Tributary Site Data Option: Culvert Invert Data

Inlet Station: 0.00 ft

Inlet Elevation: 186.18 ft

Outlet Station: 84.00 ft

Outlet Elevation: 184.54 ft

Number of Barrels: 1

Culvert Data Summary - Unnamed Tributary Barrel Shape: Circular

Barrel Diameter: 9.00 ft

Barrel Material: Corrugated Steel

Embedment: 45.60 in

Barrel Manning's n: 0.0240 (top and sides)

Manning's n: 0.0350 (bottom)

Culvert Type: Straight

Inlet Configuration: Beveled Edge (Ke=0.2)

Inlet Depression: None

Culvert Data: Flood Relief

Table 2 - Culvert Summary Table: Flood Relief 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)

46.00 cfs 0.17 cfs 191.58 0.18 0.0* 1- S2n

0.12 0.13 0.12 1.75 1.75 4.06

64.70 cfs 1.33 cfs 191.91 0.51 0.0* 1- S2n

0.33 0.36 0.33 1.91 3.12 4.00

83.40 cfs 3.48 cfs 192.24 0.84 0.0* 1- S2n

0.53 0.58 0.53 2.01 4.14 4.12

102.10 cfs 6.21 cfs 192.54 1.14 0.0* 1- S2n

0.70 0.78 0.70 2.09 4.90 4.25

120.80 cfs 9.28 cfs 192.81 1.41 0.0* 1- S2n

0.86 0.96 0.86 2.16 5.50 4.37

139.50 cfs 12.59 cfs 193.07 1.67 0.0* 1- S2n

1.01 1.13 1.01 2.22 5.99 4.50

158.20 cfs 15.97 cfs 193.32 1.92 0.162 1- S2n

1.15 1.28 1.15 2.28 6.40 4.61

176.90 cfs 19.40 cfs 193.56 2.16 0.435 1- S2n

1.28 1.41 1.28 2.33 6.74 4.71

194.00 cfs 22.51 cfs 193.77 2.37 0.696 1- S2n

1.39 1.53 1.39 2.37 7.01 4.81

214.30 cfs 26.17 cfs 194.02 2.62 1.021 1- S2n

1.52 1.65 1.52 2.41 7.28 4.91

233.00 cfs 29.54 cfs 194.26 2.86 1.340 1- S2n

1.63 1.76 1.63 2.45 7.50 5.00

* Full Flow Headwater elevation is below inlet invert.

Inlet Elevation (invert): 191.40 ft, Outlet Elevation (invert): 190.00 ft

Culvert Length: 70.01 ft, Culvert Slope: 0.0200

Culvert Performance Curve Plot: Flood Relief

Site Data - Flood Relief

Inlet Station: 0.00 ft

Inlet Elevation: 191.40 ft

Outlet Station: 70.00 ft

Outlet Elevation: 190.00 ft

Number of Barrels: 1

Culvert Data Summary - Flood Relief Barrel Shape: Circular

Barrel Diameter: 3.00 ft

Barrel Material: Corrugated Steel

Embedment: 0.00 in

Barrel Manning's n: 0.0240

Culvert Type: Straight

Inlet Configuration: Thin Edge Projecting (Ke=0.9)

Tailwater Data for Crossing: Unnamed Tributary

Table 2 - Downstream Channel Rating Curve (Crossing: Unnamed Tributary) Flow (cfs) Water

Surface Elev (ft)

Velocity (ft/s)

Depth (ft) Shear (psf) Froude Number

46.00 190.09 1.75 4.06 2.95 1.05

64.70 190.25 1.91 4.00 3.22 1.06

83.40 190.35 2.01 4.12 3.39 1.07

102.10 190.43 2.09 4.25 3.53 1.07

120.80 190.50 2.16 4.37 3.64 1.08

139.50 190.56 2.22 4.50 3.74 1.09

158.20 190.62 2.28 4.61 3.83 1.10

176.90 190.67 2.33 4.71 3.92 1.11

194.00 190.71 2.37 4.81 3.99 1.11

214.30 190.75 2.41 4.91 4.07 1.12

233.00 190.79 2.45 5.00 4.13 1.12

Tailwater Channel Data - Unnamed Tributary Tailwater Channel Option: Irregular Channel

Channel Slope: Irregular Channel

User Defined Channel Cross-Section Coord No. Station (ft) Elevation (ft) Manning's n 1 0.00 196.00 0.0550 2 10.00 190.85 0.0350 3 46.50 189.85 0.0350 4 48.50 188.34 0.0350 5 51.50 188.34 0.0350 6 53.50 189.85 0.0350 7 90.00 190.85 0.0550 8 100.00 196.00 0.0000

Roadway Data for Crossing: Unnamed Tributary Roadway Profile Shape: Constant Roadway Elevation

Crest Length: 100.00 ft

Crest Elevation: 200.32 ft

Roadway Surface: Gravel

Roadway Top Width: 28.00 ft

HY-8 Culvert Analysis Report - Existing Conditions

Crossing Discharge Data

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

Minimum Flow: 46.00 cfs

Design Flow: 194.00 cfs

Maximum Flow: 233.00 cfs

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

Headwater Elevation (ft)

Total Discharge (cfs)

Unnamed Tributary Discharge (cfs)

Floodplain Overflow Discharge (cfs)

Roadway Discharge (cfs)

Iterations

193.09 46.00 32.02 13.98 0.00 5

193.80 64.70 40.99 23.71 0.00 3

194.53 83.40 48.88 34.53 0.00 3

195.08 102.10 54.05 42.01 5.83 12

195.19 120.80 55.03 43.33 22.17 6

195.28 139.50 55.79 44.28 39.21 5

195.36 158.20 56.43 44.88 56.53 4

195.42 176.90 57.00 45.73 73.98 4

195.48 194.00 57.48 46.31 90.11 4

195.55 214.30 58.01 46.74 109.49 4

195.60 233.00 58.45 47.42 126.90 3

195.00 94.32 53.33 40.99 0.00 Overtopping

Rating Curve Plot for Crossing: Unnamed Tributary Existing Conditions

Culvert Data: Unnamed Tributary

Table 1 - Culvert Summary Table: Unnamed Tributary

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)

46.00 cfs 32.02 cfs 193.09 3.03 1.780 5-S2n 1.64 1.84 1.64 0.36 8.11 1.86

64.70 cfs 40.99 cfs 193.80 3.74 2.628 5-S2n 1.92 2.08 1.92 0.43 8.57 2.12

83.40 cfs 48.88 cfs 194.53 4.47 3.831 5-S2n 2.19 2.28 2.19 0.49 8.83 2.34

102.10 cfs 54.05 cfs 195.08 5.02 4.747 7-M2c 2.40 2.39 2.39 0.54 8.96 2.52

120.80 cfs 55.03 cfs 195.19 5.13 4.794 7-M2c 2.45 2.41 2.41 0.60 9.05 2.69

139.50 cfs 55.79 cfs 195.28 5.22 4.830 7-M2c 2.48 2.42 2.42 0.64 9.12 2.84

158.20 cfs 56.43 cfs 195.36 5.30 4.861 7-M2c 2.52 2.43 2.43 0.69 9.18 2.98

176.90 cfs 57.00 cfs 195.42 5.37 4.889 7-M2c 2.55 2.45 2.45 0.74 9.24 3.10

194.00 cfs 57.48 cfs 195.48 5.42 4.911 7-M2c 2.58 2.45 2.45 0.77 9.28 3.21

214.30 cfs 58.01 cfs 195.55 5.49 4.938 7-M2c 2.62 2.46 2.46 0.82 9.33 3.33

233.00 cfs 58.45 cfs 195.60 5.54 4.963 7-M2c 2.66 2.47 2.47 0.86 9.38 3.44

Inlet Elevation (invert): 190.06 ft, Outlet Elevation (invert): 189.06 ft

Culvert Length: 42.59 ft, Culvert Slope: 0.0233

Culvert Performance Curve Plot: Unnamed Tributary

Water Surface Profile Plot for Culvert: Unnamed Tributary

Site Data - Unnamed Tributary

Inlet Station: 0.00 ft

Inlet Elevation: 190.06 ft

Outlet Station: 42.58 ft

Outlet Elevation: 189.06 ft

Number of Barrels: 1

Culvert Data Summary - Unnamed Tributary

Barrel Shape: Circular

Barrel Diameter: 3.00 ft

Barrel Material: Corrugated Steel

Embedment: 0.00 in

Barrel Manning's n: 0.0240

Culvert Type: Straight

Culvert Data: Floodplain Overflow

Table 2 - Culvert Summary Table: Floodplain Overflow

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)

46.00 cfs 13.98 cfs 193.09 1.80 1.981 2-M2c 1.87 1.19 1.19 0.36 5.35 1.86

64.70 cfs 23.71 cfs 193.80 2.48 2.686 2-M2c 3.00 1.57 1.57 0.43 6.34 2.12

83.40 cfs 34.53 cfs 194.53 3.25 3.419 7-M2c 3.00 1.91 1.91 0.49 7.28 2.34

102.10 cfs 42.01 cfs 195.08 3.86 3.971 7-M2c 3.00 2.11 2.11 0.54 7.90 2.52

120.80 cfs 43.33 cfs 195.19 3.97 4.082 7-M2c 3.00 2.14 2.14 0.60 8.02 2.69

139.50 cfs 44.28 cfs 195.28 4.06 4.170 7-M2c 3.00 2.17 2.17 0.64 8.10 2.84

158.20 cfs 44.88 cfs 195.36 4.11 4.247 7-M2c 3.00 2.18 2.18 0.69 8.15 2.98

176.90 cfs 45.73 cfs 195.42 4.19 4.314 7-M2c 3.00 2.20 2.20 0.74 8.22 3.10

194.00 cfs 46.31 cfs 195.48 4.25 4.371 7-M2c 3.00 2.22 2.22 0.77 8.27 3.21

214.30 cfs 46.74 cfs 195.55 4.29 4.436 7-M2c 3.00 2.23 2.23 0.82 8.31 3.33

233.00 cfs 47.42 cfs 195.60 4.35 4.490 7-M2c 3.00 2.24 2.24 0.86 8.37 3.44

Inlet Elevation (invert): 191.11 ft, Outlet Elevation (invert): 191.00 ft

Culvert Length: 39.72 ft, Culvert Slope: 0.0029

Culvert Performance Curve Plot: Floodplain Overflow

Water Surface Profile Plot for Culvert: Floodplain Overflow

Site Data - Floodplain Overflow

Inlet Station: 0.00 ft

Inlet Elevation: 191.11 ft

Outlet Station: 39.72 ft

Outlet Elevation: 191.00 ft

Number of Barrels: 1

Culvert Data Summary - Floodplain Overflow

Barrel Shape: Circular

Barrel Diameter: 3.00 ft

Barrel Material: Corrugated Steel

Embedment: 0.00 in

Barrel Manning's n: 0.0240

Culvert Type: Straight

Tailwater Data for Crossing: Unnamed Tributary Existing Conditions

Table 2 - Downstream Channel Rating Curve (Crossing: Unnamed Tributary Existing Conditions)

Flow (cfs) Water Surface Elev (ft)

Velocity (ft/s) Depth (ft) Shear (psf) Froude Number

46.00 189.42 0.36 1.86 0.43 0.60

64.70 189.49 0.43 2.12 0.52 0.62

83.40 189.55 0.49 2.34 0.60 0.63

102.10 189.61 0.54 2.52 0.66 0.64

120.80 189.66 0.60 2.69 0.73 0.65

139.50 189.71 0.64 2.84 0.79 0.66

158.20 189.76 0.69 2.98 0.85 0.67

176.90 189.80 0.74 3.10 0.90 0.68

194.00 189.84 0.77 3.21 0.95 0.68

214.30 189.88 0.82 3.33 1.00 0.69

233.00 189.92 0.86 3.44 1.05 0.69

Tailwater Channel Data - Unnamed Tributary Existing Conditions

Tailwater Channel Option: Irregular Channel

Channel Slope: Irregular Channel

User Defined Channel Cross-Section

Coord No. Station (ft) Elevation (ft) Manning's n

1 0.00 191.00 0.0550

2 10.00 189.15 0.0550

3 44.00 189.10 0.0550

4 45.00 189.06 0.0350

5 55.00 189.06 0.0350

6 56.00 189.10 0.0550

7 90.00 189.15 0.0550

8 100.00 191.00 0.0000

Roadway Data for Crossing: Unnamed Tributary Existing Conditions

Roadway Profile Shape: Constant Roadway Elevation

Crest Length: 100.00 ft

Crest Elevation: 195.00 ft

Roadway Surface: Gravel

Roadway Top Width: 28.00 ft

Unnamed Tributary

Basin Characteristics

Parameter Code Parameter Description Value Unit

DRNAREA Area that drains to a point on a stream 3.2 square miles

PRECPRIS00 Basin average mean annual precipitation for 1971 to 2000 from PRISM

17 inches

Region ID: AK Workspace ID: AK20191001192210099000 Clicked Point (Latitude, Longitude): 60.73688, -150.79343 Time: 2019-10-01 12:22:31 -0700

Page 2 of 4StreamStats

10/1/2019https://streamstats.usgs.gov/ss/

Peak-Flow Statistics Parameters[Peak Areas less than 1000 sqmi SIR 2016 5024]

Parameter Code Parameter Name Value Units

Min Limit

Max Limit

DRNAREA Drainage Area 3.2 square miles

0.4 1000

PRECPRIS00 Mean Annual Precip PRISM 1971 2000

17 inches 8 280

Peak-Flow Statistics Flow Report[Peak Areas less than 1000 sqmi SIR 2016 5024]

PIl : Prediction Interval-Lower, PIu: Prediction Interval-Upper, SEp: Standard Error of Prediction, SE: Standard Error (other -- see report)

Statistic Value Unit PIl PIu SEp

2 Year Peak Flood 45.3 ft^3/s 15.8 130 70.8

5 Year Peak Flood 83.4 ft^3/s 29.6 235 69.1

10 Year Peak Flood 115 ft^3/s 40.6 323 69.2

25 Year Peak Flood 159 ft^3/s 55.1 457 71.2

50 Year Peak Flood 194 ft^3/s 65.9 570 72.8

100 Year Peak Flood 233 ft^3/s 77.5 699 74.6

200 Year Peak Flood 273 ft^3/s 87.9 847 77.4

500 Year Peak Flood 330 ft^3/s 101 1080 81.9

Peak-Flow Statistics Citations

Curran, J.H., Barth, N.A., Veilleux, A.G., and Ourso, R.T.,2016, Estimating Flood Magnitude and Frequency at Gaged and Ungaged Sites on Streams in Alaska and Conterminous Basins in Canada, Based on Data through Water Year 2012: U.S.

Geological Survey Scientific Investigations Report 2016-5024, 47 p.

(http://dx.doi.org/10.3133/sir20165024http://dx.doi.org/10.3133/sir20165024)

USGS Data Disclaimer: Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S.

Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty.

Page 3 of 4StreamStats

10/1/2019https://streamstats.usgs.gov/ss/

SCALE IN FEET

10 0 10 20 30 40

OUTLETINLETPIPEHYDRAULIC INFORMATION

0 20 40 60 8020406080

LENGTH: 84 ft

PIPE SLOPE: 0.0196 ft/ft

HEADWALL: Conc./Riprap

FLOWLINE SLOPE: 0.0196 ft/ft

100 120100120140

Q : 46 CFS

Q : 194 CFS

BANKFULL CHANNEL WIDTH: 3.0 ft

TYPE: Metal round culvert SPAN: 9.0 ft RISE: 9.0 ft

LOWER BEVEL HEIGHT: 2.25 ft LOWER BEVEL HEIGHT: 2.25 ft

BEVEL: 1.5h : 1v

HEADWALL: Conc./Riprap

BEVEL: 1.5h : 1v

Q : 233 CFS

INV N/E/EL: 2462070.14/1498348.10/186.18' /1498402.88/184.54'INV N/E/EL: 2462133.82

WALL THICKNESS: NA

:1

Existing ground

Flow

Flow

Remove two exisiting 36" CMP's

HW : 194.26 ft

Unnamed Tributary

N

LC

OHW : 191.58 ft

Slope 1.96%

Line to be constructed

BURIAL DEPTH: 3.8 ft BURIAL DEPTH: 3.8 ft

1:1

New culvert centerline metal round culvert.

9 foot diameter

131+54.58

131+71.75, 36.12 LT

131+35.68, 39.74' RT

PLAN AND PROFILE

CULVERT

UNNAMED TRIBUTARY

[1]method B, class 3

Placed riprap

[1]method B, class 3

Placed riprap

[1]method B, class 3

Placed riprap [1]method B, class 3

Placed riprap detail Sheet G.13

Backfill with streambed material per

FOOTNOTE:

See Sheet G.11 for riprap details.[1]

G.3

STATE PROJECT

NUMBER

SHEET

AK FWS KNA 74525(1)

J N e ig h o r n

/2

/2

C h e c k e d b y

D e s ig n e d b y

In t_ ft

D c p w w o r k \d

\a k r k e n a i1 h .d g n

Road centerline

Channel elev. 188.34

Channel elev. 189.98

Channel flowline

Road grade

:1

A

M

J u ly per detail sheet G.14

Install rock weirs at 12' spacing

End channel grading

Concrete collar

Begin channel grading

Concrete collar

Begin channel grading

See Sheet G.12 for details.

Concrete collar.

Cut and fill limits (typ.)

End channel grading

See Sheet G.12 for details.

Concrete collar.

1:1 1'

TYPICAL SECTION

CHANNEL GRADING

4" depth and seed

Place topsoil, round 36" diameter CMP

Install overflow culvert

.5

5°

.5

8'-0"

3' bankfull width

NOTE:

FOOTNOTE:

DETAILS

RIPRAP HEADWALL

Sl op e

PIPE BEVEL DETAIL

Sl op e

SKEW ANGLE DIAGRAM

c e n te r li n e

R o a d w a y

Cu lv er t ce nt er lin e

BOP

EOP

(DIAMETER OR SPAN GREATER OR EQUAL TO 48-INCHES)

(DIAMETER OR SPAN LESS THAN 48-INCHES)

.2

D o r R

.2

D o r R o r R is e

R

D ia m e te r

D o r R is e

R

D ia m e te r

D

W

Sl op e

FRONT VIEW SIDE VIEW

[2

24" shown in the plans

Streambed material where shown in the plans

Streambed material where

V a ri a b le R is e

W2

Variable W2

V a ri a b le R is e

Placed riprap, class 3

Placed riprap, class 3

[3

" m in geotextile, class 1, type C

Separation and stabilization

Manufacturer's standards

0.25 D or R or per the

Optional

Skew

N e ig h o r n

/2

/2

C h e c k e d b y

D e s ig n e d b y

G.11

STATE PROJECT

NUMBER

SHEET

In t_ ft m y f il e s \p w p r o d u c ti o n

\d

\m t-a e z .d g n

AK FWS KNA 74525(1)

:5

A u g u s t beneath and at all sides of placed riprap.

Place earthwork geotextile between riprap and existing ground, Earthwork geotextile, type II-C is subsidiary to 251.

Contractor to field verify all invert elevations, prior to installation.

3.

2.

1.

shown on site specific details, whichever is greater.

Construct riprap end treatment to a thickness of 36-inches or as[3]

Riprap end treatment slope to match roadway embankment slope.[2]

Bevel to match roadway embankment.[1]

RIPRAP END TREATMENT

[1]

[1]

V

B e v a

N e ig h o

/2

/2

C h e c k e d b y

D e s ig n e d b y

G.12

STATE PROJECT

NUMBER

SHEET

In t_ ft m y f il e s \p w p r o d u c ti o n

\d

\m t-a e z .d g n

AK FWS KNA 74525(1)

:5

A u g u s t

SECTION VIEW

ANCHOR BOLT DETAIL

1.5

3'-0"

TYPICAL SECTION

THRU COLLAR

CONCRETE COLLAR

ISOMETRIC VIEW

3'-0"

3'

Sp an

3'

LC

Culvert crown

2' min. lap splice

#4 Reinf (6 total)

Culvert invert galvanized " Dia.4 bolt design - 4" hook

Acceptable anchorStructural plate pipe

18" o.c. See detail " Anchor bolt @4

#4

#4 stirrups m in

2' min. lap splice

#4 Reinf (6 total)

6" min.

To bedrock or 3' max.

To bedrock or 3' max.

COLLAR DETAILS

REINFORCED CONCRETE

LARGE CULVERT

SECTION A-A

PLAN

NOTE:

FOOTNOTE:

3.

2.

1.

Pipe arch culvert

W

Streambed sediment

Streambed cobble

Pipe arch culvert wall

Box culvert wall

Stagger in-channel fish passage boulders within the culvert span.

streambed cobble, and bank stone gradations.

See special contract requirements for streambed sediment, Mix streambed cobbles evenly throughout streambed sediment.

Channel flowline

Streambed sedimentRound pipe culvert wall Streambed top

Round culvert

Culvert wall

LC

Flow

BB

A where specified on plan

Sediment retention sill on plan where specified

Rock weir culvert boulder within

Fish passage where specified on plan

Sediment retention sill culvert boulder within

Fish passage

NO SCALE

Streambed Material.

Infill informational quantities are incidental to ITEM 64704-1000 [4] dimension.

smallest 4 3 Embed fish passage boulders within active channel [3] sediment where listed in the infill quantities table.

Construct well defined banks with bank stone and streambed[2] parabolic shape.

Slope streambed aggregate towards flowline to ensure[1]

[1]Channel flowline

[2]Bank stone

[2]Bank stone

TREATMENT

STREAM CULVERT

SIMULATED

A Flow

SECTION B-B

36" min.

Streambed cobble

Culvert outlet where specified on plan

Sediment retention sill

[3]within culvert

Fish passage boulder

Streambed sediment plan sheet or Length on

LC

specified on plan

Rock weir where outlet

Culvert

LOCATION

(FT)

X

(CUYD)

COBBLE

STREAMBED

(CUYD)

SEDIMENT

STREAMBED

(CUYD)

STONE

BANK

GRADATION

COBBLE

STREAMBED

(FT)

W

MITIGATION

FISH PASSAGE BOULDER

(IN)

DIA. NO.

[4]STREAMBED MATERIAL

TOTAL

.B e v

N e ig h o

/2

/2

C h e c k e d b y

D e s ig n e d b y

G.13

STATE PROJECT

NUMBER

SHEET

In t_ ft m y f il e s \p w p r o d u c ti o n

\d

\m t-a e w

.d g n

AK FWS KNA 74525(1)

:4

A u g u s t

SUCKER CREEK NA 16 24 4

UNNAMED TRIBUTARY NA 3 24 7

RAINBOW LAKE NA 6 18 5

C

D

B

(FT)

BD

1.5

3% (typ.)

Slope

295 295 39

B D

W

X (typ.)

B u ri a l d e p thd e p th

B u ri a l

X (typ.)

match rock weir spacing

Stagger fish boulders each side and

B

/3

Flow

F lo wA

A

(in)

DIAMETER

FOOTER ROCK

TOP ROCK AND

(no.)

QUANTITY

ROCK WEIR

MITIGATION

ROCK WEIR

(ft)

B

(ft)

[5] Z

(ft)

W

LOCATION

ELEVATION

PLAN

SECTION A-A

DETAIL

ROCK WEIR

NO SCALE

FOOTNOTE:

[4] [3]Footer rock

Z

D o w n s tr e a m f r o m c o n tr o l)

Top rock

Bottom of channel

Bottom of channel

[4] [3]Footer rock high water level

Ordinary normal low flow

Edge of water

Control point

6[3] [2]Top rock streambed material elevation or top of

Original streambed

[4] [3]Footer rock

[3]Top rock water level

Ordinary high

BWB

B W3

W 3

W3

B

W3

B e v

N e ig h o

/2

/2

C h e c k e d b y

D e s ig n e d b y

G.14

STATE PROJECT

NUMBER

SHEET

In t_ ft m y f il e s \p w p r o d u c ti o n \d

\m t-a e y .d g n

AK FWS KNA 74525(1)

:5

A u g u s t

SUCKER CREEK 16 1.75 6 4

UNNAMED TRIBUTARY 3 3 1.5 7

RAINBOW LAKE 6 1.5 3 5

Align footer rocks flush against bed retention sills inside culvert. [5] and stable foundation for the top rocks.

Place footer rocks close together to create a tightly packed[4] streambed material.

Fill voids in top rock and footer rock with specified[3]

Space top rocks in center 1/3 only.[2]

Orient top rocks to deflect water towards center of stream.[1]

[2] [1] [2] [1]

[2]

[2]

[2] [2] [2]

[2]

VAP

Existing ground

Roadway centerline

2000 50 100 15050100150200250300

Unnamed Tributary

250 300 350

Section 703. — AGGREGATE

703.18 Furnished Streambed Material. (Added Subsection).

Streambed material consists of streambed sediment and streambed cobbles (class A, B, C, or D as specified on the plans) with volumes of each specified on the plans. Provide a uniform mixture.

Furnish material consisting of hard, durable, free from seams, cracks, and other defects conforming to the following:

(a) Durability index, AASHTO T 210

(1) Coarse aggregate 35 min.

(2) Fine aggregate 35 min.

(b) Apparent specific gravity, AASHTO T 85 2.55 min.

(c) Los Angles abrasion, AASHTO T 96 50% max.

(d) Gradation, Streambed Sediment. Furnish material meeting the gradation requirements of Table 703-13. Conserve round or sub-round material from the culvert and roadway excavation meeting the requirements of Table 703-13 to use as streambed sediment.

Table 703-13 Streambed Sediment Gradation

Sieve Size

Percent by Weight Passing Designated Sieve

(AASHTO T 27 and T 11)

6 inch 100

4 inch 75 – 85

3 inch 65 – 75

1 ½ inch 50 – 60

3/4 inch 35 – 45

No. 4(1) 15 – 25

No. 10 15 min.

(1) No more than 0.2 percent woody debris retained.

(e) Gradation, Streambed Cobbles. Furnish material meeting the requirements of Table 703-14. Conserve round or sub-round material from the roadway excavation meeting the requirements of Table 703-14 to use as streambed cobbles.

Table 703-14 Streambed Cobbles Gradation(1)

Nominal Size

Percent less than the nominal size Class

A B C D 28" 100 20” 65-75 14" 100 35-45 12" 100 85-95 30-40 8" 65-75 45-55 10-20 6" 45-55 30-40 4" 100 35-45 20-30 0-10 3" 30-40 15-25 2"

1 ½" 35-45 0-10 0-10 ¾" 10-15

(1) Grading of the cobbles will be by visual inspection of material before it is placed, and if directed by the CO, by placing material on a flat surface and sorting and measuring a sampling of the cobbles.

Note: Approximate size can be determined by taking the average dimension of the three axes of the rock; length, width, and thickness by use of the following calculation:

𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿ℎ + 𝑊𝑊𝑊𝑊𝑊𝑊𝐿𝐿ℎ + 𝑇𝑇ℎ𝑊𝑊𝑖𝑖𝑖𝑖𝐿𝐿𝐿𝐿𝑖𝑖𝑖𝑖

= 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝑊𝑊𝐴𝐴𝐴𝐴𝐿𝐿𝐿𝐿 𝑆𝑆𝑊𝑊𝑆𝑆𝐿𝐿

Project:

Location/Stream:

New Stream Channel Design (Culvert, Rock Ramp)

FINE 50%

Using Corps of Engineers Equations - FHWA Circular on Development in the River System - Page 6.25. COARSE 50% FHWA NHI 01-004; River Engineering for Highway Encroachments, 2001 http://www.fhwa.dot.gov/engineering/hydraulics/library_arc.cfm?pub_number=8&id=20

YELLOW ARE INPUTS

Safety Factor 1.2 Stability Coefficient for Incipient Failure 0.36 (0.36 round rock, 0.3 angular rock) Vertical Velocity Distribution Coeff 1.00 (1.0 for straight channels) Blanket Thickness Coeff 1 (1xD100 or 1.5 or D50 max, whichever is greater) Local depth of flow 2.37 ft for 50 year event Unit Weight of water 62.4 lb/ft^3 assumed Unit weight of rock 165 lb/ft^3 assumed Local depth-average velocity 8.22 ft/s from 50-year event avg. velocity in pipe Side Slope correction factor 1 Gravitational Acceleration 32.2 ft/s^2 D85/D15 1.7 (1.7-5.2) D50/D30 1 Note: This method is based on the minimum D30 size Riprap Design Method - Selecting Proper Gradation, Page 131.

Design Hydrology and Sedimentology for Small Catchments, Haan, Barfield and Hayes, 1981.

D15 0.2 ft 3.0 inches D30 0.5 ft 6.0 inches D50 0.6 ft 7.0 inches D85 1.0 ft 12.0 inches

D100 1.1 ft 14.0 inches

Using D50 size, used FHWA circular for Rip Rap design to spec out D100, D85 and D15.

D100 = 2.0D50

Fuller-Thompson Estimating for Maximum Density: D100 (inches) 14.0 Method Adapted from US Forest Service Stream Simulation Guidelines D30 6.0 Stability (D30):

D30 Req'd 6.0

YELLOW ARE INPUTS COARSE FINES

Custom Fine Aggreg. Combined %F-T EQN Check Coarse Material Design -D30 Required p RELATIVE % = 0.50 0.50 1.0000 Riprap D30 Riprap Req 6.0

Size (inches) Sieve Size % Passing % Passing % Passing % Passing % Passing D30 Size = 6.0 48 48 in 1.00 1.00 100% 185% 100% No OK 44 44 in 1.00 1.00 100% 177% 100% No 42 42 in 1.00 1.00 100% 173% 100% No 36 36 in 1.00 1.00 100% 160% 100% No 30 30 in 1.00 1.00 100% 146% 100% No 20 20 in 1.00 1.00 100% 120% 100% No 14 14 in 1.00 1.00 100% 100% 100% No 12 12 in 0.90 1.00 95% 93% 90% No 8 8 in 0.50 1.00 75% 76% 50% No 6 6 in 0.30 1.00 65% 65% 30% 6.00 4 4 in 0.20 0.80 50% 53% 20% 4.00 3 3 in 0.15 0.70 43% 46% 15% 3.00

1.5 1.5 in 0.00 0.55 28% 33% 0% 1.50

0.75 0.75 in 0.00 0.40 20% 23% 0% 0.75

0.187 #4 0.00 0.20 10% 12% 0% 0.19

0.0787 #10 Sand 0.00 0.15 8% 7% 0% 0.08

Gradation values should be within +/-5% of this gradation (Rice) AND we need to have at least 5% sand size (#10) or smaller (Forest Service) in the combined gradation

DATA for Graph & Fuller-Thomson Eqn Size (in) Combined % pa F-T equation

48.000 100% 185%

44.000 100% 177%

42.000 100% 173%

36.000 100% 160%

30.000 100% 146%

20.000 100% 120%

14.000 100% 100%

12.000 95% 93%

8.000 75% 76%

6.000 65% 65%

4.000 50% 53%

3.000 43% 46%

1.500 28% 33%

0.750 20% 23%

0.187 10% 12%

0.079 8% 7%

OK

MATERIAL PROPORTIONS

AK FWS Kenai 74525(1) - Swan Lake / Swanson Rive

Unnamed Tributary Culvert

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0.010 0.100 1.000 10.000 100.000

P as si n g

Particle Size

Design

Fuller‐Thomson

YELLOW ARE INPUTS

Desired tolerance (+/-): 5%

SIEVE % PASSING

12 in 1.00 8 in 1.00 6 in 1.00 4 in 0.75 to 0.85 3 in 0.65 to 0.75

1.5 in 0.5 to 0.6

0.75 in 0.35 to 0.45

#4 0.15 to 0.25 #10 Sand 0.15 min

Desired tolerance (+/-): 5%

SIZE % PASSING

48 in 1.00 44 in 1.00 42 in 1.00 36 in 1.00 30 in 1.00 20 in 1.00 14 in 1.00 12 in 0.85 to 0.95 8 in 0.45 to 0.55 6 in 0.3 to 0.4 4 in 0.2 to 0.3

3 in 0.15 to 0.25

TABLE 1

FINE MATERIAL

TABLE 2

COARSE MATERIAL

Roadway Data for Crossing: Unnamed Tributary

Streambed Material Sizing Analyzer_Unnamed Trib

Roadway Data for Crossing: Unnamed Tributary

6-HY8Report_Unnamed Tributary

Streambed Material Sizing Analyzer_Unnamed Trib