BOARDMAN RIVER WALL STABILIZATION

PROJECT

DOWNTOWN DEVELOPMENT AUTHORITY MEETING

APRIL 16, 2021

PROJECT CONTEXT

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Study Area-100 and 200 blocks of East Front Street

Front Street

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WALL CONDITIONS

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Existing Wall

River Scouring Under Wall

Existing Surface

Soil Subsidence

Timber Piles Supporting Wall

Existing 24”Sanitary Sewer

Wall Cross Section Looking West

WALL CONDITIONS

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Wall Elevation View From River

Summary of Issues• Continued soil subsidence = pavement failure and disappearing parking

signs.• Issues with multiple sanitary sewer service line failures and river pollution.• Ground water infiltration into sanitary sewer increases treatment plant costs

and potential for sewage releases into river.• Long term destabilization of wall and sewer main.

WALL ASSESSMENT PROCESS

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Elements of the Study• Topographic Survey

• Geotechnical Soil Borings

• Inspection of wall and review of existing documents

• Engineering Alternatives

• Hydraulic Modeling

• Evaluation and Recommendations

ALTERNATIVES CONSIDERED

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Alternatives Considered Include-

• Sheet Pile on Land Side of the Wall

• Concrete Filled Geotextile Tube

• Cores in the Footer • Wall Removal and

Sewer Relocation• Sheet Pile Wall

Protection

Criteria for Evaluation of Alternatives1. Provide long term protection for

adjacent properties and sanitary sewer.

2. Maintain the alley and service access on the north side of the commercial buildings.

3. Limit impact on the flooding elevation of the river; especially upstream of the project area.

4. Preserve opportunities in the future to achieve the developing goals of the UNIFIED PLAN

5. Be cost effective.

1. Protect from scouring and soil loss

2. Backfill voids in soil

ALTERNATIVES EVALUATION

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Alternatives

Long Term Protection –

Adjacent Properties and Sanitary Sewer

Maintain Alley and Service

Functions

Limit Flood Impacts to

Project Area

Achieves goals of the Unified Plan

Cost Effective*

Overall Rating

Sheet Pile –Land Side

2 3 3 1 2 2

Concrete Filled

Geotextile1 3 1 1 1 1

Cores in Footer

1 3 3 1 1 2

Wall Removal &

Sewer Relocation

3 2 3 3 3 3

Sheet Pile –River Side

3 3 2 1 3 2.5

RECOMMENDATION – 100 BLOCK

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Plan of 100 Block

Section of 100 Block

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RECOMMENDATION – 100 BLOCK

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100 Block of Front St, looking east

RECOMMENDATION – 200 BLOCK

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Plan of 200 Block

Section of 200 Block

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HYDRAULIC MODELLING RESULTS

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River Bottom

River SurfaceP

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Profile of River Looking South

The recommended approach will lead to a rise in flood elevation within the project area of approximately 0.10 feet but does not result in a change upstream or downstream from the project area.

UNIFIED PLAN

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DISCUSSIONS TO DATE

Key priorities from the Community Engagement Process

• Providing public access

• Soften shore treatment/restore natural edge

• Remove/Limit parking from riverbanks

• Utilize best practices to manage stormwater and other means of improving water quality.

• Shift the balance towards habitat and nature over human recreation and economic development

• Keep river corridor natural and passive

SHORT-TERM MEASURES

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1. Coordinate potential FEMA permitting with the Fish Pass project

2. Enact a monitoring program to track potential infrastructure failures between now and construction, including-

Survey of the existing wall and monitoring the wall’s cant biannually

Place benchmark nails in the pavement to the south of the wall and track their elevation fluctuations monthly

Measure the width of pavement cracks monthly

Measure point locations of scour depth monthly

Conduct annual underwater scour inspections

Monitor flows in the wastewater line to identify new infiltration resulting from a break in the sewer line

Televise the existing 24” sanitary sewer main and sewer service connections in both the 100 and 200 blocks

STEPS FORWARD

Seek support for project by elected and appointed officials.

Find source(s) of funding to limit financial impact to residents

Submit for Permits

Prepare Final Engineering Plans and Specifications

Bidding and Construction

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