River Nason Confluence Project - Yakama Nation Fisheriesyakamafish-nsn.gov/sites/default/files/projects... · Nason Confluence Project – Concept Design Report June 2015 3 a major

Wenatchee River –Nason Confluence Project Concept Design Report SUBMITTED TO

Yakama Nation Fisheries

Wenatchee River –Nason Confluence Project Concept Design Report

SUBMITTED TO

Yakama Nation Fisheries PO Box 151 Toppenish, WA 98948 PREPARED BY

Inter‐Fluve, Inc. 501 Portway Ave., Suite 101 Hood River, OR 97031

June 30, 2015

Nason Confluence Project – Concept Design Report

i

Table of Contents

INTRODUCTION ................................................................................................................................... 1

Overview .......................................................................................................................................... 1

Project Area Description ................................................................................................................... 1

Goals and objectives ........................................................................................................................ 2 Regional Habitat Objectives and Priorities ........................................................................................... 2 Upper Wenatchee River Reach Assessment and Habitat Restoration Strategy ................................... 3

SITE CONDITIONS AND ANALYSIS ......................................................................................................... 4

Fish Use and Habitat Conditions ....................................................................................................... 4

Geomorphology ............................................................................................................................... 5

Hydrology ........................................................................................................................................ 6 Seasonal Hydrology ............................................................................................................................... 6 Peak Flow Hydrology............................................................................................................................. 7

Site Survey and Data Collection ........................................................................................................ 8

Hydraulic Modeling .......................................................................................................................... 8

PRELIMINARY DESIGN CRITERIA ........................................................................................................... 9 Habitat .................................................................................................................................................. 9 Geomorphology/Hydrology .................................................................................................................. 9 Engineering and Risk ............................................................................................................................. 9 River Safety ........................................................................................................................................... 9 Construction Impacts .......................................................................................................................... 10

DESCRIPTION OF PROJECT COMPONENTS .......................................................................................... 10

Component 1: Wenatchee Mainstem Large Wood and Off‐Channel Enhancement .......................... 10

Component 2: Nason Left Bank Large Wood and Off‐Channel Enhancement Site A ......................... 11

Component 3: Nason Left Bank Off‐Channel Enhancement Site B ................................................... 12

Component 4: Nason Right Bank Large Wood and Side‐Channel Enhancement ............................... 13

REFERENCES ....................................................................................................................................... 14

Appendix A – Hydraulic Modeling Output


June 2015 1

Introduction OVERVIEW

This report presents concept designs for aquatic habitat restoration at the Nason Confluence project area

in Chelan County, WA. This project area contains approximately 900 feet of Nason Creek upstream from

the confluence with the Wenatchee River, and 700 feet of the Wenatchee River. The purpose of this

project is to enhance habitat for Endangered Species Act (ESA) listed Chinook, steelhead, and bull trout.

Lower Nason Creek and the mainstem Upper Wenatchee River were identified in the 2014 Upper

Columbia Salmon Recovery Board (UCSRB) Regional Technical Team (RTT) Biological Strategy (UCRTT

2014) as Tier 1 watersheds of highest protection priority. Nason Creek was listed as the highest priority

watershed for restoration in the entire basin, with the mainstem Upper Wenatchee River ranked as

second highest out of eleven assessment units evaluated. Restoration in the Nason Confluence project

area is important because it contains major spawning areas for spring Chinook and steelhead, while also

supporting coho and bull trout for a portion of their life cycle. Stream functioning in the project area is

currently impaired due to reduced large wood recruitment, channel complexity, and gravel recruitment.

PROJECT AREA DESCRIPTION

The project area includes the lower 900 feet of Nason Creek and 1,200 feet of streambank along the right

bank of the mainstem Wenatchee River. The area is approximately 13 acres in size (Figure 1). The

confluence occurs at river mile 53.7 along the Wenatchee River, only 0.5 miles downstream from the

outlet of Lake Wenatchee. Except for portions of the active point and mid‐channel bars, the project area,

including the islands in the mainstem Wenatchee, are vegetated with a mix of trees and shrubs. A large

island near the confluence in the Wenatchee River has a large log jam at its apex that creates pool habitat

off its south and west ends. An alcove 600 feet upstream from the confluence on the Wenatchee River

offers backwater habitat. All property within the project area is United States Forest Service.


June 2015 2

Figure 1. Overview of project area and landownership. The project is located within US Forest Service land.

GOALS AND OBJECTIVES

Regional Habitat Objectives and Priorities

Regional objectives for salmonid habitat protection and restoration in the Upper Columbia Region have

been evaluated and summarized in the document A Biological Strategy to Protect and Restore Salmonid

Habitat in the Upper Columbia Region (2014) by the Upper Columbia Salmon Recovery Board (UCSRB)

Regional Technical Team (RTT). This Biological Strategy is part of the Upper Columbia Spring Chinook

Salmon and Steelhead Recovery Plan (UCSRB 2007) and recommends region‐wide biological

considerations and approaches for salmonid habitat restoration and protection actions. The RTT guides

the development and evaluation of salmonid recovery projects within the Upper Columbia Region.

The Biological Strategy has identified several assessment units within the major watersheds of the Upper

Wenatchee River. The Nason Confluence project area falls within the Upper Wenatchee Assessment Unit.

Both the Upper Wenatchee mainstem and Nason Creek are Tier 1 watersheds of highest protection

priority. Nason Creek is the highest priority watershed for restoration in the entire Wenatchee River

Basin, while the Upper Wenatchee River is the second highest. The Upper Wenatchee River is considered


June 2015 3

a major spawning area for spring Chinook and steelhead, a stronghold for summer Chinook, and a bull

trout overwintering area. Nason Creek is a major spawning area for spring Chinook and steelhead, a

stronghold for coho, and a bull trout overwintering area (UCRTT 2014).

All Chinook spawning that occurs in Nason Creek occurs in the lower 15 miles of the mainstem, which

also contains the poorest quality habitat (UCRTT 2014). The 2014 Biological Strategy identified the

following factors impairing habitat conditions in the Upper Wenatchee River and Nason Creek:

Reduced large wood recruitment, channel migration, and gravel recruitment due to the state

highway, railroad, and private land development.

State highway cut off a large oxbow near the Nason Creek confluence.

Reduced large wood recruitment and channel complexity due to historic logging.

The RTT has prioritized a list of restoration actions to address these factors impeding salmon recovery

goals for the Upper Wenatchee Assessment Unit. Actions that are relevant to the Nason Confluence

project area are listed below (UCRTT 2014):

1. Channel structure and form: Restore habitat diversity by enhancing large woody material

recruitment, retention, and complexity.

2. Peripheral and transitional habitat: Improve fish access to oxbows and historical side channels

that have been cut off from main channel.

3. Riparian condition: Improve riparian conditions to improve long term LWD recruitment.

Wenatchee River Subbasin Plan Key Management Strategies

The Northwest Power and Conservation Council (NWPCC) completed the Wenatchee Subbasin Plan in

2004 to identify and prioritize actions needed to recover listed salmonids in tributary habitats within the

Columbia River Basin (NWPCC 2004). This document identified the following limiting factors for

salmonids in Nason Creek: key habitat, floodplain connectivity, habitat diversity, channel stability,

sediment, flow, temperature, obstructions, and competition.

Key management strategies for Nason Creek that are relevant to the Nason Confluence project area

include (NWPCC 2004):

Improve elevated stream temperatures in the lower mainstem (below Mill Creek) by improving

low flow conditions, channel confinement, and degraded riparian conditions

Reduce fine sediment level in the lower mainstem

Improve riparian and floodplain characteristics in the lower mainstem (below Mill Creek) where

feasible

Improve in‐channel attributes in the lower mainstem.

Upper Wenatchee River Reach Assessment and Habitat Restoration Strategy

The Upper Wenatchee River stream corridor assessment, which covered the mainstem of the Wenatchee

River from RM 35.5 at the upstream end of Tumwater Canyon to RM 54.5 at Lake Wenatchee, was


June 2015 4

completed in 2012 by the Yakama Nation (Inter‐Fluve 2012). The goal of the assessment was to evaluate

aquatic habitat and watershed processes in the Upper Wenatchee River and to identify specific habitat

restoration strategies. This effort included assessments and development of restoration strategies within

the Nason Confluence project area.

Restoration strategies were developed by comparing existing aquatic habitat conditions to target

conditions obtained from reference areas and regional habitat thresholds. Reasons for impairment in the

Nason Confluence project area included impaired off‐channel habitat, lack of cover in existing backwater

areas, and impaired channel migration associated with the state highway bridge over the Wenatchee

River. The following restoration actions were recommended:

Enhance connectivity to off channel habitat

Address artificial confinement within the Nason Creek fan area

Incorporate bar apex jams to control grade and raise the channel bed over time

Place large wood along the channel to increase pool habitat and channel complexity

Site Conditions and Analysis FISH USE AND HABITAT CONDITIONS

Current fish use in the project area includes ESA‐listed spring Chinook (endangered), steelhead

(threatened), bull trout (threatened), and non‐listed summer Chinook, coho, and westslope cutthroat

trout. Spring and summer Chinook, coho, steelhead, and bull trout all utilize the Wenatchee River and/or

Nason Creek in the project area for migrating, spawning, and rearing. Past redd counts show the

presence of Chinook and steelhead spawning in the confluence area, as well as near the riffle in Nason

Creek at the upstream end of the project area (Figure 2) (UCSRB 2004). Adult migration through the

project area has been impaired by lack of large wood and low number of pools, which provide velocity

refuge for migrating adults. The project area also contains poor rearing habitat due to lack of large wood,

low habitat diversity, and lack of off‐channel habitat. According to the Subbasin Plan (NWPCC 2004),

lower Nason Creek has the poorest quality fish habitat of any tributary in the upper Wenatchee Subbasin.

Restoring habitat in lower Nason Creek could increase populations of Chinook, coho, steelhead, and bull

trout.


June 2015 5

Figure 2. Steelhead redds were observed within the project area at the mouth of Nason Creek, while Chinook redds were observed both at the mouth and in the channel of Nason Creek.

GEOMORPHOLOGY

The project area includes approximately 900 feet of lower Nason Creek and its floodplain as well as

approximately 1,200 feet of streambank along river‐right of the mainstem Wenatchee River. Within the

project area, the average gradient of Nason Creek is 0.38% and the average gradient of the Wenatchee

River is 0.33%. Immediately upstream from the confluence the channel of Nason Creek has been

characterized as a glide. The glide has low habitat complexity (no log jams and only a few pieces of large

wood). Upstream from this glide, at the upper‐most portion of the project area, is a riffle. At the

downstream end of the riffle on river‐left is a large gravel bar. A large active point bar is located on river‐

right at the confluence itself. The substrate is composed of gravels and small cobbles. The substrate on the

bed of the channel is loose and unarmored, suggesting regular active sediment mobilization and

deposition.

Within the project area, Nason Creek and its active floodplain surfaces are partially confined.

Confinement on the western border (river‐left side) is by a steep hillslope composed of glacial till deposits

and on the eastern border (river‐right side) by a low alluvial terrace composed of Nason Creek fan

deposits and the armored road embankment of Highway 207 (at the upstream end of the project area).


June 2015 6

Vegetation on the active low floodplain surfaces are dominated by thick stands of alder and vine maple.

Large conifers, with less‐dense undergrowth, cover the higher active floodplain surfaces. The floodplain

along river‐left of Nason Creek has a well‐vegetated riparian zone with two backwater features that are

partially connected to Nason Creek and the Wenatchee River. The largest backwater feature runs along

the toe of the glacial till deposits that constrain the western border of the project area. The downstream

end of this backwater is wetted during low flow. The floodplain along river‐right of lower Nason Creek

contains a high‐flow channel that runs along the toe of the alluvial terrace behind the point bar feature at

the confluence. This feature is activated during high‐flow events from Nason Creek and then empties into

the Wenatchee River.

Channel migration in Nason Creek is limited within the project area, as well as up and downstream.

Upstream from the project area, riprap and other bank armoring confine natural migration along river‐

right at privately owned properties. The armored road embankment of State Highway 207 that runs

along the eastern border (river‐right side), and upstream of the project area, disconnects Nason Creek

from a large oxbow complex as well as Nason Creek’s historical alluvial fan. The Highway 207 bridge

abutments and related riprap also constrain the location of the Wenatchee River and thus the dynamic

processes that historically occurred at the confluence between the two rivers.

HYDROLOGY

Seasonal Hydrology

The Upper Wenatchee River is a snowmelt‐dominated system (Figure 3). The snowmelt runoff typically

occurs during spring and early summer, and is driven by changes in ambient air temperature, snowpack

mass, and the elevation distribution of the season’s snowpack. Peak runoff usually occurs from April

through July, with the highest rates occurring in late June. The Wenatchee returns to baseflow in

September.


June 2015 7

Figure 3. Mean monthly flows for the Wenatchee River below the Nason Creek confluence. Monthly average flows were calculated using data from the USGS gage ‘Wenatchee River at Plain, WA’ and correcting for the project site using a basin‐area correction.

The hydrology of the study area is significantly affected by Lake Wenatchee. Temporary storage in the

lake buffers the snowmelt runoff signal from the Little Wenatchee and White River, which contribute 40%

of the total annual runoff to the Wenatchee. Thus, runoff from some of the highest elevation, and highest

precipitation, regions of the basin are moderated by temporary storage in Lake Wenatchee.

Peak Flow Hydrology

Flood frequency data for the project area were obtained from the basin hydrology work performed by the

US Bureau of Reclamation as part of the Nason Creek Tributary Assessment (USBR 2008). As part of the

USBR analysis, peak flow estimates were generated using the USGS regional regression equations and a

regional gage analysis. The results for three locations within the confluence area are provided in Table 1.

Table 1. Peak flow estimates for three locations within the confluence area at a range of flood recurrence intervals. Data obtained from US Bureau of Reclamation hydrologic analysis (2008).

Recurrence Interval (years)

Discharge (cfs)

Wenatchee above Nason Confluence

Nason at mouth Wenatchee Below Nason Confluence

2 6,817 908 7,725 5 9,082 1,391 10,473 10 10,784 1,775 12,559 25 13,180 2,340 15,520 50 15,156 2,822 17,978 100 17,304 3,361 20,665

0

500

1000

1500

2000

2500

3000

3500

4000

4500

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Discharge

(cfs)

Month

Mean Monthly Flow at Nason Confluence Project Area(Wenatchee River below Nason Confluence)


June 2015 8

SITE SURVEY AND DATA COLLECTION

Topographic and bathymetric data were collected April 6‐10 and May 27‐29 of 2015 using rtkGPS and

total station survey equipment. The bathymetric data were collected using a single beam echosounder

mounted to a inflatable cataraft and tied into survey control on site. The data collection focused on

capturing channel cross sections for hydraulic modeling, as well as topographic points in floodplain areas

to inform design. We relied on existing LiDAR data for other floodplain areas where restoration actions

are unlikely to occur. Control points were placed on the state highway bridge as well as the gravel bar

located at the confluence.

To locate the survey data in space, we collected static data at the rtkGPS base station, and the data were

adjusted using the National Geodetic Survey’s (NGS) Online Positioning User Service (OPUS). The

surveyed data were based on the Washington State Plane North coordinate system with the North

American Datum of 1983. Metadata from the NGS solution indicated a root mean squared error within

0.007 meters for the horizontal coordinates and 0.004 meters for the elevation.

HYDRAULIC MODELING

Existing channel and floodplain hydraulics were simulated using the U.S. Army Corps of Engineers

Hydraulic Engineering Center River Analysis System (HEC‐RAS 4.1.0; USACE 2010). HEC‐RAS is a

computer program that models the hydraulics of water flow through natural rivers and other channels.

The program is one‐dimensional, meaning that there is no direct modeling of the hydraulic effect of

lateral cross section shape changes, bends, and other two‐ and three‐dimensional aspects of flow. The

hydraulic model calculates channel and floodplain water surface elevations, velocities, depths, and shear

stresses (among other metrics) for various input flows.

The model geometry was developed using topographic and bathymetry data obtained through surveys

completed in April and May 2015 by Inter‐Fluve. Survey data were supplemented with LiDAR

(Watershed Sciences 2007) data in select locations. Model geometry for existing conditions were sampled

from the combined Inter‐Fluve ground base survey and LiDAR. Cross sections extended through the

floodplains to the valley walls. The 2‐, 5‐, 10‐, 25‐, 50‐, and 100‐year recurrence interval floods were

modeled as well as a number of low flows. The lowest flow included in the model of 468 cfs was the

lowest average daily discharge recorded on a calendar day at the Wenatchee River USGS gage at Plain,

with the same calendar flow from the USGS Chiwawa gage subtracted. Values for Manning’s n

coefficient of hydraulic roughness were estimated from professional judgment to be 0.038 along the

cobble‐bedded channel and 0.060 along the moderately vegetated floodplains. The models were run in

subcritical mode with a downstream normal depth boundary condition based on an energy slope slightly

higher than the model reach results to avoid an artificial backwater condition.

Proposed conditions were not modeled at this conceptual level and will be included as part of later

phases of design. Many of the project elements include backwater and side channel enhancements or

creations along the floodplain and would not impact the mainstem hydraulics. Large wood along the

mainstem banks would increase Manning’s n values slightly but are not anticipated to have a significant

impact on channel hydraulics. The results of the modeling are presented in Appendix A.


June 2015 9

Preliminary Design Criteria A suite of preliminary design criteria have been developed that incorporate stakeholder objectives, the

RTT Biological Strategy, the Yakama Nation Reach Assessment, physical river constraints, construction

impacts, aesthetics, and recreational user risk. Design criteria serve three primary purposes: 1) to clearly

document and communicate specific project objectives and constraints, 2) to help inform and guide the

design process so that objectives are met, and 3) provide a basis for future performance monitoring. The

design criteria include preliminary performance criteria as well as prescriptive criteria. The design criteria

will be refined as the design process moves forward and as more information becomes available to make

criteria more specific and quantitative. The design criteria are divided into 6 categories: Habitat,

Geomorphology/Hydrology, Engineering and Risk, River Safety, and Construction Impacts.

Habitat

Improve habitat conditions for ESA‐listed salmon and steelhead, using the RTT prioritized

actions for the Upper Wenatchee Assessment Unit (UCRTT 2014), including the following:

o Channel structure and form: Restore habitat diversity by enhancing large woody

material recruitment, retention, and complexity.

o Peripheral and transitional habitat: Improve fish access to oxbows and historical side

channels that have been cut off from main channel.

o Riparian condition: Improve riparian conditions to improve long term LWD

recruitment.

Geomorphology/Hydrology

Design projects that are consistent with current and projected hydrologic and geomorphic

patterns and processes

Allow for naturally dynamic and deformable processes to operate, within the constraints

imposed by existing landownership, infrastructure, and safety considerations

To the extent possible, design side‐channels to maintain sediment transport continuity in order to

maximize design life and reduce in‐filling

Engineering and Risk

Do not increase flooding or erosion risk of public or private infrastructure

Provide adequate ballasting of placed logs to withstand high flows that overtop the structures

(i.e. compensate for buoyancy)

Specific stability and other design criteria of placed structures to be determined in subsequent

design phases

River Safety

Take into account visibility of structures from upstream

Take into account structure form to minimize entrapment potential

Minimize channel encroachment to the extent possible to allow for avoidance by river users


June 2015 10

Construction Impacts

Minimize impacts to intact wetland habitat

Minimize impacts to fish during the construction process by reducing the need for dewatering

and worksite isolation during construction

Locate and configure construction access routes to utilize existing access where possible and to

minimize impacts to existing mature riparian vegetation

Utilize onsite resources or plan channel alignments to take advantage of existing natural features

where feasible (e.g. trees, beaver dam locations)

Description of Project Components COMPONENT 1: WENATCHEE MAINSTEM LARGE WOOD AND OFF‐CHANNEL ENHANCEMENT

Description and Potential Benefits

This component includes two primary elements: 1) large wood habitat cover along the banks of the

mainstem Wenatchee and within an existing small alcove, and 2) the creation of a new backwater alcove

channel with large wood placements that would connect into the mainstem Wenatchee at the existing

smaller alcove.

The mainstem large wood would include small jams to enhance channel margin complexity and cover.

Some local pool scour and sediment sorting would also likely occur at the structures, but they would not

be large or stable enough to have a significant long‐term effect on geomorphic processes such as channel

migration. The primary purpose would be to address the RTT’s “channel structure and form” priority.

The primary fish benefit would be for rearing cover for juvenile salmonids and holding cover for adults.

The off‐channel alcove would increase juvenile off‐channel rearing habitat using excavation of a new

alcove area connected at a wide range of flow conditions. This component would help to increase the

availability of “peripheral and transitional habitat”. The primary fish benefit would be for overwintering

habitat for juvenile salmonids, but year‐round use would also be possible. The specific level of targeted

seasonal inundation will be further evaluated in later design stages. Large wood would be placed

throughout the backwater area to increase habitat complexity and cover.

Floodplain roughness wood would be placed along the disturbed temporary access corridor in the low

area between the created alcove and the existing high flow alcove to the south (Component 2 area). The

purpose of this roughness would be to add hydraulic roughness to the area of vegetation disturbance

from construction. Riparian enhancement using planting of native woody species would occur

throughout areas disturbed as part of construction activities.

Design Considerations

The potential for filling in of this backwater by sediments is believed to be relatively low due to the

upstream influence of Lake Wenatchee.

There is the potential for future beaver activity in the constructed off‐channel area. Based on the current

understanding of beaver activity and fish habitat, beaver use of the area is believed to be compatible with,

and will potentially enhance, fish use and habitat quality.


June 2015 11

The preferred route for access is being evaluated by the Yakama Nation. Pending landowner discussions,

access could occur via Highway 207 and using a temporary bridge to cross Nason Creek at the riffle at the

upstream end of the project area. There may be an alternate access route via the southwest side through

US Forest Service and/or State Park land. These potential access routes will be evaluated further in later

design stages.

The location and extent of excavation work will depend on the results of future wetlands assessment in

the area and consultation with permitting agencies.

COMPONENT 2: NASON LEFT BANK LARGE WOOD AND OFF‐CHANNEL ENHANCEMENT SITE A


This component includes two primary elements: 1) large wood habitat cover along the river‐left bank of

lower Nason Creek, and 2) the expansion of an existing backwater alcove channel with large wood

placements that would connect into Nason Creek just upstream of the confluence.

The mainstem large wood would include small jams to enhance channel margin complexity and cover.

Some local pool scour and sediment sorting would also likely occur at the structures, but they would not

be large or stable enough to have a significant long‐term effect on geomorphic processes such as channel

migration. The primary purpose would be to address the RTT’s “channel structure and form” priority.

The primary fish benefit would be for rearing cover for juvenile salmonids and holding cover for adults.

The existing backwater alcove (see cover photo) would be expanded by greater than 600 feet and would

be enhanced using large wood placements. Expanding and enhancing the existing off‐channel alcove

would increase juvenile off‐channel rearing habitat by creating much greater off‐channel rearing capacity

and habitat quality at a wider range of flow conditions. This component would help to increase the

availability of “peripheral and transitional habitat”. The primary fish benefit would be for overwintering

habitat for juvenile salmonids, but year‐round use would also be possible. The specific level of targeted

seasonal inundation will be further evaluated in later design stages. Large wood would be placed

throughout the backwater area to increase habitat complexity and cover.

Floodplain roughness wood would be placed along the disturbed temporary access corridor at the

upstream end of the alcove. The purpose of this roughness would be to add hydraulic roughness to the

area of vegetation disturbance from construction. Riparian enhancement using planting of native woody

species would occur throughout areas disturbed as part of construction activities.


There is potential for filling in of this backwater by Nason Creek sediments. The outlet, however, is

located at a lateral scour pool, which reduces the potential for bedload deposition (fines will still deposit).

The existing lower end of the alcove is connected at low flows, which suggests that periodic high flows

may scour this channel.





June 2015 12





design stages.

The specific location and extent of excavation work will depend on the results of future wetlands

assessment in the area and consultation with permitting agencies.

COMPONENT 3: NASON LEFT BANK OFF‐CHANNEL ENHANCEMENT SITE B


This component includes the expansion and enhancement of an existing high flow backwater alcove that

would connect into Nason Creek approximately 300 feet upstream of the confluence. The existing channel

scar would be expanded using excavation to deepen the alcove by approximately 150‐200 feet along its

length. Large wood would be added for habitat complexity and cover.

Expanding and enhancing the existing high flow alcove would increase juvenile off‐channel rearing

habitat by creating greater off‐channel rearing capacity and habitat quality at a wider range of flow

conditions. This component would help to increase the availability of “peripheral and transitional

habitat”. The primary fish benefit would be for overwintering habitat for juvenile salmonids, but year‐

round use would also be possible. The specific level of targeted seasonal inundation will be further

evaluated in later design stages.

Floodplain roughness wood could potentially be placed along the disturbed temporary access corridor at

the upstream end of the alcove. The purpose of this roughness would be to add hydraulic roughness to

the area of vegetation disturbance from construction. Riparian enhancement using planting of native

woody species would occur throughout areas disturbed as part of construction activities.


There is potential for filling in of this backwater by Nason Creek sediments. The outlet is located at the

downstream end of an existing gravel point bar. This area will need to be further evaluated for the

potential for filling with bedload.








design stages.

The specific location and extent of excavation work will depend on the results of future wetlands

assessment in the area and consultation with permitting agencies.


June 2015 13

COMPONENT 4: NASON RIGHT BANK LARGE WOOD AND SIDE‐CHANNEL ENHANCEMENT


This component includes two primary elements: 1) large wood habitat cover along the river‐right bank of

lower Nason Creek, and 2) the creation of flow‐through side‐channel habitat.

The large wood component would include small jams along approximately 400 feet of bank to enhance

channel margin complexity and cover. Some local pool scour and sediment sorting would also likely

occur at the structures, but they would not be large or stable enough to have a significant long‐term effect

on geomorphic processes such as channel migration. The primary purpose would be to address the RTT’s

“channel structure and form” priority. The primary fish benefit would be for rearing cover for juvenile

salmonids and holding cover for adults.

Side‐channel enhancement would occur using excavation in an existing high flow channel scar that is

approximately 550 feet long. The channel would originate on Nason Creek approximately 250 feet

upstream of the confluence and would flow into the mainstem Wenatchee approximately 200 feet

upstream of the Hwy 207 Bridge. The side‐channel would increase juvenile off‐channel rearing habitat

and would also be capable of supporting steelhead spawning. This component would help to increase the

availability of “peripheral and transitional habitat”. The specific level of targeted seasonal

inundation/flow will be further evaluated in later design stages. Large wood would be placed throughout

the side‐channel to increase habitat complexity, cover, sediment sorting, and pool scour. A bar apex jam

could potentially be constructed at the inlet to help divert and maintain the flow‐split. This will be

evaluated further in later stages of design.

Floodplain roughness wood would be placed along the bar in several locations adjacent to the side‐

channel to encourage flow within the side‐channel and to restore roughness that would historically have

been present along the gravel bars. Riparian enhancement using planting of native woody species would

occur throughout areas disturbed as part of construction activities.


In general, there would be risk of filling or other channel adjustment to this side‐channel. This is due to

the inherent risks of working within a depositional fan environment. The risks are greater with a flow‐

through side‐channel since bedload could be entrained into the channel entrance. Measures would be

taken to limit the filling risk to the extent possible (i.e. by adjusting the angle, invert elevation, and size of

the inlet), but there would still remain some risk nonetheless. The greatest risk of filling would occur as a

result of alluvial deposits following a large flood event on Nason Creek. Excavating this side channel at

the downstream end may allow it to function as a backwater even if the upstream end is cut off by

transported bed material.

The preferred route for access is being evaluated by the Yakama Nation. Access is likely to occur off of

Hwy 207 just south of the bridge across the Wenatchee.

The location and extent of excavation work will depend on the results of future wetlands assessment in

the area and consultation with permitting agencies.


June 2015 14

References Inter‐Fluve Inc. 2012. Upper Wenatchee River Stream Corridor Assessment and Habitat Restoration

Strategy. Prepared for Yakama Nation Fisheries, Upper Columbia Habitat Restoration Project,

Toppenish, WA.

Northwest Power and Conservation Council (NWPCC). 2004. Wenatchee Subbasin Plan.

U.S. Bureau of Reclamation (USBR). 2008. Nason Creek Tributary Assessment, Chelan County, WA. USDI

USBR Technical Service Center, Denver, CO and Pacific Northwest Regional Office, Boise, Idaho.

Upper Columbia Regional Technical Team (UCRTT). 2014. A Biological strategy to protect and restore

salmonid habitat in Upper Columbia Region (revised). A Report to the Upper Columbia Salmon

Recovery Board from the Upper Columbia Regional Technical Team.

Upper Columbia Salmon Recovery Board (UCSRB). 2007. Upper Columbia salmon and Steelhead

recovery plan: Upper Columbia Salmon Recovery Board, Wenatchee, Washington, 300 pp. Web site:

http://www.ucsrb.com/plan.asp.

Watershed Sciences, Inc. 2007. LiDAR remote sensing data collection: upper & lower Okanogan River,

Methow River, Lake Roosevelt, Wenatchee River and John Day River Study Areas. Prepared for:

Puget Sound LiDAR Consortium, Seattle, WA.

Appendix A

HEC-‐RAS Results Wenatchee River - Nason Confluence Project

Nason

1400.13947.63

754.01666.2

530.56

340.89

Na

son_

a

t_confl

Wenatchee_us

1535.45

1382.961112.13

Wena t chee

Wenatchee_ds

833.48

653.13508.7

392.97

259.66

42.38

Wena t chee

Nason_Confl

0 200 400 600 800 1000 1200 1400 16001860

1865

1870

1875

1880

1885

Nason-Confl Plan: NasonCnfl_Ex 6/27/2015

Main Channel Distance (ft)

Ele

vatio

n (f

t)

Legend

WS 100yr

WS 50yr

WS 25yr

WS 10yr

WS 5yr

WS 2yr

WS 5000cfs

WS 2000cfs

WS 1000cfs

WS 468cfs

Ground

LOB

ROB

259.

66

392.

97

508.

7

653.

13

833.

48

1112

.13

1272

.04

1382

.96

1535

.45

Wenatchee Wenatchee_ds Wenatchee Wenatchee_us

0 500 1000 1500 2000 25001860

1865

1870

1875

1880

1885

1890

Nason-Confl Plan: NasonCnfl_Ex 6/27/2015

Main Channel Distance (ft)

Ele

vatio

n (f

t)

Legend

WS 100yr

WS 50yr

WS 25yr

WS 10yr

WS 5yr

WS 2yr

WS 5000cfs

WS 2000cfs

WS 1000cfs

WS 468cfs

Ground

LOB

ROB

259.

66

392.

97

508.

7

653.

13

833.

48

340.

89

530.

56

666.

2

754.

01

833.

23

947.

63

1078

.7

1273

.76

1400

.13

Wenatchee Wenatchee_ds Nason_at_confl Nason

0 100 200 300 400 5001872

1874

1876

1878

1880

1882

1884

1886

Nason-Confl Plan: NasonCnfl_Ex 6/27/2015 River = Nason_at_confl Reach = Nason RS = 1400.13

Station (ft)

Ele

vatio

n (f

t)

Legend

WS 100yr

WS 50yr

WS 25yr

WS 10yr

WS 5yr

WS 2yr

WS 5000cfs

WS 2000cfs

WS 1000cfs

WS 468cfs

Ground

Bank Sta

.06 .038 .06

0 100 200 300 400 5001872

1874

1876

1878

1880

1882

1884

1886


Station (ft)

Ele

vatio

n (f

t)

Legend

WS 100yr

WS 50yr

WS 25yr

WS 10yr

WS 5yr

WS 2yr

WS 5000cfs

WS 2000cfs

WS 1000cfs

WS 468cfs

Ground

Bank Sta

.06 .038 .06

0 100 200 300 400 500 6001872

1874

1876

1878

1880

1882

1884


Station (ft)

Ele

vatio

n (f

t)

Legend

WS 100yr

WS 50yr

WS 25yr

WS 10yr

WS 5yr

WS 2yr

WS 5000cfs

WS 2000cfs

WS 1000cfs

WS 468cfs

Ground

Bank Sta

.06 .038 .06

0 100 200 300 400 500 600 7001872

1874

1876

1878

1880

1882

1884


Station (ft)

Ele

vatio

n (f

t)

Legend

WS 100yr

WS 50yr

WS 25yr

WS 10yr

WS 5yr

WS 2yr

WS 5000cfs

WS 2000cfs

WS 1000cfs

WS 468cfs

Ground

Bank Sta

.06 .038 .06

0 200 400 600 8001870

1872

1874

1876

1878

1880

1882


Station (ft)

Ele

vatio

n (f

t)

Legend

WS 100yr

WS 50yr

WS 25yr

WS 10yr

WS 5yr

WS 2yr

WS 5000cfs

WS 2000cfs

WS 1000cfs

WS 468cfs

Ground

Bank Sta

.06 .038 .06

0 200 400 600 800 10001870

1872

1874

1876

1878

1880

1882

1884

1886


Station (ft)

Ele

vatio

n (f

t)

Legend

WS 100yr

WS 50yr

WS 25yr

WS 10yr

WS 5yr

WS 2yr

WS 5000cfs

WS 2000cfs

WS 1000cfs

WS 468cfs

Ground

Bank Sta

.06 .038 .06

0 200 400 600 800 10001870

1872

1874

1876

1878

1880

1882

1884

1886


Station (ft)

Ele

vatio

n (f

t)

Legend

WS 100yr

WS 50yr

WS 25yr

WS 10yr

WS 5yr

WS 2yr

WS 5000cfs

WS 2000cfs

WS 1000cfs

WS 468cfs

Ground

Bank Sta

.06 .038 .06

0 200 400 600 800 1000 12001870

1880

1890

1900

1910

1920

1930


Station (ft)

Ele

vatio

n (f

t)

Legend

WS 100yr

WS 50yr

WS 25yr

WS 10yr

WS 5yr

WS 2yr

WS 5000cfs

WS 2000cfs

WS 1000cfs

WS 468cfs

Ground

Bank Sta

.06 .038 .06

0 200 400 600 800 1000 12001868

1870

1872

1874

1876

1878

1880

1882

1884

1886


Station (ft)

Ele

vatio

n (f

t)

Legend

WS 100yr

WS 50yr

WS 25yr

WS 10yr

WS 5yr

WS 2yr

WS 5000cfs

WS 2000cfs

WS 1000cfs

WS 468cfs

Ground

Bank Sta

.06 .038 .06

0 100 200 300 400 500 600 7001860

1870

1880

1890

1900

1910

1920

1930

1940

Nason-Confl Plan: NasonCnfl_Ex 6/27/2015 River = Wenatchee Reach = Wenatchee_us RS = 1535.45

Station (ft)

Ele

vatio

n (f

t)

Legend

WS 100yr

WS 50yr

WS 25yr

WS 10yr

WS 5yr

WS 2yr

WS 5000cfs

WS 2000cfs

WS 1000cfs

WS 468cfs

Ground

Bank Sta

.06 .038 .06

0 100 200 300 400 500 600 700 8001870

1875

1880

1885

1890

1895

1900

1905

1910


Station (ft)

Ele

vatio

n (f

t)

Legend

WS 100yr

WS 50yr

WS 25yr

WS 10yr

WS 5yr

WS 2yr

WS 5000cfs

WS 2000cfs

WS 1000cfs

WS 468cfs

Ground

Bank Sta

.06 .038 .06

0 100 200 300 400 500 600 7001865

1870

1875

1880

1885

1890

1895


Station (ft)

Ele

vatio

n (f

t)

Legend

WS 100yr

WS 50yr

WS 25yr

WS 10yr

WS 5yr

WS 2yr

WS 5000cfs

WS 2000cfs

WS 1000cfs

WS 468cfs

Ground

Bank Sta

.06 .038 .06

0 100 200 300 400 500 600 7001865

1870

1875

1880

1885

1890

1895


Station (ft)

Ele

vatio

n (f

t)

Legend

WS 100yr

WS 50yr

WS 25yr

WS 10yr

WS 5yr

WS 2yr

WS 5000cfs

WS 2000cfs

WS 1000cfs

WS 468cfs

Ground

Bank Sta

.06 .038

0 100 200 300 400 500 6001865

1870

1875

1880

1885

1890

1895

Nason-Confl Plan: NasonCnfl_Ex 6/27/2015 River = Wenatchee Reach = Wenatchee_ds RS = 833.48

Station (ft)

Ele

vatio

n (f

t)

Legend

WS 100yr

WS 50yr

WS 25yr

WS 10yr

WS 5yr

WS 2yr

WS 5000cfs

WS 2000cfs

WS 1000cfs

WS 468cfs

Ground

Bank Sta

.06 .038 .06

0 100 200 300 400 5001865

1870

1875

1880

1885

1890

1895


Station (ft)

Ele

vatio

n (f

t)

Legend

WS 100yr

WS 50yr

WS 25yr

WS 10yr

WS 5yr

WS 2yr

WS 5000cfs

WS 2000cfs

WS 1000cfs

WS 468cfs

Ground

Bank Sta

.06 .038 .06

0 100 200 300 400 5001865

1870

1875

1880

1885

1890

1895


Station (ft)

Ele

vatio

n (f

t)

Legend

WS 100yr

WS 50yr

WS 25yr

WS 10yr

WS 5yr

WS 2yr

WS 5000cfs

WS 2000cfs

WS 1000cfs

WS 468cfs

Ground

Bank Sta

.06 .038 .06

0 100 200 300 400 500 6001860

1865

1870

1875

1880

1885

1890

1895


Station (ft)

Ele

vatio

n (f

t)

Legend

WS 100yr

WS 50yr

WS 25yr

WS 10yr

WS 5yr

WS 2yr

WS 5000cfs

WS 2000cfs

WS 1000cfs

WS 468cfs

Ground

Bank Sta

.06 .038 .06

0 100 200 300 400 5001865

1870

1875

1880

1885

1890

1895


Station (ft)

Ele

vatio

n (f

t)

Legend

WS 100yr

WS 50yr

WS 25yr

WS 10yr

WS 5yr

WS 2yr

WS 5000cfs

WS 2000cfs

WS 1000cfs

WS 468cfs

Ground

Bank Sta

.06 .038 .06

0 100 200 300 400 5001865

1870

1875

1880

1885

1890

1895

1900


Station (ft)

Ele

vatio

n (f

t)

Legend

WS 100yr

WS 50yr

WS 25yr

WS 10yr

WS 5yr

WS 2yr

WS 5000cfs

WS 2000cfs

WS 1000cfs

WS 468cfs

Ground

Bank Sta

.06 .038 .06

HEC-RAS Plan: Existing

River Reach River Sta Profile Q Total Min Ch El W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl Shear Chan

(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft) (lb/sq ft)

Wenatchee Wenatchee_us 1535.45 468cfs 47.00 1867.07 1871.58 1871.58 0.000006 0.13 373.54 243.92 0.02 0.00




Wenatchee Wenatchee_us 1535.45 2yr 908.00 1867.07 1876.17 1876.18 0.000019 0.53 1715.64 305.71 0.04 0.01




































Wenatchee Wenatchee_ds 833.48 468cfs 468.00 1868.94 1871.28 1871.34 0.002932 1.94 241.79 274.35 0.36 0.16




Wenatchee Wenatchee_ds 833.48 2yr 7725.00 1868.94 1875.76 1876.06 0.001604 4.41 1761.41 379.80 0.36 0.47






Wenatchee Wenatchee_ds 653.13 468cfs 468.00 1868.28 1870.69 1870.16 1870.77 0.003398 2.21 211.84 219.10 0.40 0.20




































Wenatchee Wenatchee_ds 259.66 10yr 12559.00 1865.34 1874.94 1873.91 1876.87 0.007031 11.17 1139.86 223.38 0.78 2.76




HEC-RAS Plan: Existing (Continued)













Nason_at_confl Nason 1400.13 468cfs 421.00 1873.86 1876.17 1876.30 0.002529 2.92 155.31 95.56 0.38 0.29




Nason_at_confl Nason 1400.13 2yr 6817.00 1873.86 1881.67 1882.54 0.003707 8.26 1226.82 377.95 0.57 1.50










Nason_at_confl Nason 1273.76 2yr 6817.00 1873.00 1880.79 1879.51 1881.98 0.004966 9.51 943.33 292.93 0.66 1.99


































































HEC-RAS Plan: Existing (Continued)



Nason_at_confl Nason 340.89 468cfs 421.00 1869.58 1872.44 1872.06 1872.80 0.009436 4.79 87.82 61.57 0.71 0.84










LOCATION MAPSTATE OF WASHINGTON

VICINITY MAP SITE MAP

501 Porway Avenue, Suite 101Hood River, OR 97031

541.386.9003www.interfluve.com

COVER SHEET, DRAWING LIST,AND LOCATION MAPS

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PreliminaryNot for Construction

IDAHO

BELLINGHAM

SEATTLE SPOKANE

PORTLAND

OREGON

ELLENSBURG

WENATCHEE

YAKIMA

LEAVENWORTH

EVERETT

Leavenworth

Coles CornerHwy 2

Skykomish

Lake Wenachee

Plain

Nason Creek

Wenatchee River

Wenatchee River

207

Happy ClownRestaurant

Lake WenatcheeVillage

HeadwatersSpirits andBrewing

Brae Burn Rd

State Park Rd

NF-660

5

4.0 mi. to

Cole's Corner

COORDINATES:LATITUDE 47° 48' 28" NLONGITUDE 120° 43' 01" W

SECTION 28, TOWNSHIP 27N, RANGE 17E

WATERBODY: NASON CREEK

TRIBUTARY OF: WENATCHEE RIVER

DRAWING LIST1 Cover Sheet, Drawing List, and Location Maps

2 Existing Conditions, Ownership, and Access

3 Proposed Conditions and Sheet Index

4 Wenatchee Mainstem Large Wood and Off-Channel Enhancement

5 Nason Left Bank Large Wood and Off-Channel Enhancement Site A

6 Nason Left Bank Off-Channel Enhancement Site B

7 Nason Right Bank Large Wood and Side-Channel Enhancement

8 LWM Typical Details

9 LWM Typical Details

NTS

Hwy

207

Unn

amed

Cam

pgro

und

Rd

PROJECT AREA

WENATCHEE RIVER - NASON CONFLUENCE PROJECTCONCEPTUAL DESIGN

PLAN



EXISTING CONDITIONS,OWNERSHIP, AND ACCESS

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SCALE IN FEET

0 400200

Wenatchee River

Wenatchee River

Brae Burn Rd

Unnamed Campground Rd

Highway 207

LEGEND

Nason Creek

NOTE:POTENTIAL TEMPORARY ACCESSROUTES ARE PENDING FURTHEREVALUATION.

TEMPORARY CROSSING,LOCATION TO BE DETERMINED

PROPERTY LINES

LIMITS OF DISTURBANCE

EXISTING CHANNEL

EXISTING UNIMPROVED ROAD

TEMPORARY ACCESS ROAD

PLAN



PROPOSED CONDITIONSAND SHEET INDEX

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SCALE IN FEET

0 400200

MARGIN WOOD ANDBACKWATER 1, SEE SHEET 4

BACKWATER 2, SEE SHEET 5

BACKWATER 3,SEE SHEET 6

SIDE CHANN

EL,SEE SHEET 7

Nason Creek

Wenatchee River

Wenatchee River

LEGENDPROPERTY LINES




EXISTING CHANNEL

PROPOSED CHANNEL

PROPOSED LWM PLACEMENT

Brae Burn Rd

Unnamed Campground Rd

Highway 207

LONGITUDINAL PROFILE THROUGH BACKWATER CHANNEL 1

1870

1880

1870

1880

0+00 1+00 2+00 3+00 4+00 5+00 5+84

TIE IN TO EXISTING GRADETIE IN TO EXISTING GRADE

EXISTING GRADE

PROPOSED GRADE

PLAN VIEW OF BACKWATER CHANNEL 1



WENATCHEE MAINSTEM LARGE WOODAND OFF-CHANNEL ENHANCEMENT

4 OF 9

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SCALE IN FEET

0 12060

HABITAT COVER WOOD,TYP, SEE SHEET 9

BACKWATER HABITATWOOD, TYP, SEE SHEET 8

BACKWATERCHANNEL 1CENTERLINE

SCALE: 1" = 60'

SCAL

E: 1

" = 1

2'

5x VERTICAL EXAGGERATION

LEGENDEXISTING CONTOURS (1-FT INTERVAL)

PROPOSED CONTOURS (1-FT INTERVAL)


EXISTING CHANNEL

PROPOSED CHANNEL

PROPOSED CENTERLINE ALIGNMENT



4+00

FLOODPLAIN ROUGHNESSWOOD, TYP, SEE SHEET 9

NOT TO SCALE41 TYPICAL CROSS SECTION

PROPOSED CHANNEL

NASON CREEK

WENATCHEE RIVER


1860

1870

1880

1860

1870

1880

0+00 1+00 2+00 3+00 4+00 5+00 6+00 7+00 8+00 9+00 9+33

PROPOSED GRADE

EXISTING GRADE





NASON LEFT BANK LARGE WOOD ANDOFF-CHANNEL ENHANCEMENT SITE A

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SCALE IN FEET

0 16080

BACKWATER 2, SEEPROFILE BELOW

BACKWATER HABITATWOOD, TYP, SEE SHEET 8

SCALE: 1" = 80'

SCAL

E: 1

" = 1

6'


LEGEND


NASON CREEK

NASON CREEK


PROPOSED CHANNEL

WEN

ATCH

EE R

IVER

EXISTING CONTOURS (1-FT INTERVAL)



EXISTING CHANNEL

PROPOSED CHANNEL



4+00


1870

1880

1870

1880

0+00 1+00 2+00 2+95

EXISTING GRADE


PROPOSED GRADE




NASON LEFT BANK OFF-CHANNELENHANCEMENT SITE B

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SCALE IN FEET

0 6030

BACKWATER 3, SEE PROFILE BELOW

BACKWATER HABITATWOOD, SEE SHEET 8

SCALE: 1" = 30'

SCAL

E: 1

" = 6

'


LEGEND


PROPOSED CHANNEL

NASON CREEK




EXISTING CHANNEL

PROPOSED CHANNEL


4+00

LONGITUDINAL PROFILE THROUGH SIDE CHANNEL

1860

1870

1880

1860

1870

1880

0+00 1+00 2+00 3+00 4+00 5+00 6+00 6+41

TIE IN TO EXISTING GRADEPROPOSED GRADE

EXISTING GRADE

TIE IN TO EXISTING GRADE

PLAN VIEW OF SIDE CHANNEL



NASON RIGHT BANK LARGE WOODAND SIDE-CHANNEL ENHANCEMENT

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SCALE IN FEET

0 12060

SCALE: 1" = 60'

SCAL

E: 1

" = 1

2'


LEGEND


PROPOSED CHANNEL






EXISTING CHANNEL

PROPOSED CHANNEL



4+00


HABITAT COVERWOOD, SEE SHEET 9

HABITAT COVERWOOD, SEE SHEET 9

LOCK LOG INTO EXISTINGTREES AND/OR PILE

FASTEN LOGS TO PILE

PROPOSED GRADE

EXISTING GRADE

OHW

OLW

NOTES:

SPECIFIC ORIENTATION OF LOGS AND BALLAST MATERIALSMAY VARY FROM TYPICAL DRAWINGS DEPENDING ON SIZEAND SHAPE OF MATERIAL DELIVERED OR SALVAGED.

BRACING TO EXISTING TREES OR INSTALLED VERTICALLOGS WILL OCCUR AT LOCATIONS IDENTIFIED IN THE FIELDTO PROVIDE HORIZONTAL STABILITY. FILLER LOGS ANDTREE TOPS WILL BE INSTALLED AT "RACKING" LOCATIONSTO EMULATE NATURAL DEBRIS ACCUMULATIONS AND TOOPTIMIZE FISH HABITAT.

T

O

P

O

F

B

A

N

K

T

O

P

O

F

B

A

N

K

NOT TO SCALE81 SECTION - TYPICAL BACKWATER HABITAT WOOD

FLOW

COVER HABITAT LOGS

T

O

E

O

F

B

A

N

K

T

O

E

O

F

B

A

N

K

SLASH

PARTIALLY BURIED LOGS

VERTICALSNAG

NOT TO SCALE82 PLAN - TYPICAL BACKWATER HABITAT WOOD



LWM TYPICAL DETAILS

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EXISTING GRADE

FASTEN LOGS TO PILE

LOGFASTEN LOGS TO PILE

VERTICAL SNAG

PROPOSED GRADE

FASTEN LOGS TO PILE

LOGVERTICAL SNAG

POOL

FLOW

OHW

OLW

NOT TO SCALE94 PLAN - TYPICAL HABITAT COVER WOOD

NOT TO SCALE93 SECTION - TYPICAL HABITAT COVER WOOD

VIBRASONICALLYDRIVEN TIMBERPILE, TYP

NOTES

SPECIFIC ORIENTATION OF LOGS AND BALLAST MATERIALS MAY VARY FROM TYPICALDRAWINGS DEPENDING ON SIZE AND SHAPE OF MATERIAL DELIVERED OR SALVAGED.

BRACING TO EXISTING TREES OR INSTALLED VERTICAL LOGS WILL OCCUR ATLOCATIONS IDENTIFIED INTHE FIELD TO PROVIDE HORIZONTAL STABILITY.

ACCEPTABLE VIBRASONIC PILE DRIVING EQUIPMENT SHALL INCLUDE: HMC MOVAXSONIC SIDE GRIP VIBRATORY PILE DRIVER – MODEL SP80 OR EQUIVALENT.INSTALLATION BY EXCAVATION, HAMMERING OR VIBRATORY PLATE COMPACTORSHALL NOT BE ALLOWED.

15'

MIN

LOG WITHROOTWAD

SLASHLOG WITHOUTROOTWAD

VIBRASONICALLYDRIVEN TIMBERPILE, TYP

LOG WITH ROOTWAD

LOG WITHOUTROOTWAD

NOT TO SCALE91 PLAN - TYPICAL FLOODPLAIN ROUGHNESS WOOD

NOT TO SCALE92 SECTION - TYPICAL FLOODPLAIN ROUGHNESS WOOD

FLOW

FLOW



LWM TYPICAL DETAILS

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Documents

River Nason Confluence Project - Yakama Nation Fisheriesyakamafish-nsn.gov/sites/default/files/projects... · Nason Confluence Project – Concept Design Report June 2015 3 a major