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BUILDING STRONG®and Taking Care of People!
“The views, opinions and findings contained in this report are those of the authors(s) and should not be construed as an official Department of the Army position, policy or decision, unless so designated by other official documentation.”
Flood Risk ManagementFeasibility Study
Public Meeting
16 August 2018
DUPAGE RIVER, ILLINOIS
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Opening Remarks
Colonel Aaron ReisingerU.S. Army Corps of EngineersCommander, Chicago District
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Welcome
Scott Killinger, P.E.Will County Chief Subdivision Engineer
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Presenter
Erin Maloney, P.E.US Army Corps of Engineers
Chicago District
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AGENDA
How the U.S. Army Corps got involved
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How flood problem areas were identified and evaluated
What solutions were considered
What is being proposedWhat was studied
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Public comments
Questions (after presentation)
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Study LocationWatershed Area: 378 mi2
West Branch DuPage River 128 mi2
East Branch DuPage River 81 mi2
Mainstem DuPage River 169 mi2
Main Waterways:West Branch DuPage River 32 miEast Branch DuPage River 24 miMainstem DuPage River 27 miLily Cache Creek 14 mi(tributary to mainstem)
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Historic Flooding
West Branch at Winfield CreekApril 2013
DuPage Mainstem at I-55 and Black RdJuly 1996
DuPage Mainstem at River RoadSeptember 2008
1996 – Up to 17 inches of rainfall over 24 hrs. Extensive structure damages, flooding at major roadways including Interstate 55.
2008 – Up to 10 inches of rainfall over 51 hrs. FEMA Individual Assistance (IA) totals: $2,300,000 (DuPage), $1,100,000 (Will).
2010 – Up to 7 inches of rainfall over 24 hrs. Impacts primarily on East and West Branches. FEMA IA total: $5,100,000 (DuPage).
2013 – Up to 7 inches of rainfall in 24 hrs. Record stages at several watershed gages. FEMA IA totals: $14,800,000 (DuPage), $4,300,000 (Will).
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Study Scope
Overbank Elevated Groundwater
Local Sewer Backup
Evaluate Major Sources of Flooding
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Why is the U.S. Army Corps of Engineers, Chicago District
involved?
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Authorized by Congress(Section 206, Flood Control Act of 1958)
“…surveys for flood control and allied purposes…Watersheds of the Illinois River, at and in the vicinity of Chicago, Illinois”
New Start funding received in 2015
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DuPage County Stormwater Management Committee
Will County Executive Office
Chicago District
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Non-Federal Sponsor
US Army Corps of Engineers
Project Partners
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How flood problem areas were identified and evaluated
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Public & Agency ParticipationJuly 2015Feasibility study start
July 2018Public review and comment period starts
November 2015NEPA scoping meeting with public
September 2015Site visit with sponsors and municipalities
March 2017Analysis validation with sponsors and municipalities
November 2015Coordination meeting with Federal agencies
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Identifying Problem Areas
34 Damage Areas identified
Grouped into 31 Damage Reaches based on proximity for plan formulation and economic evaluation
Site Visits Public InputReview
FEMA Flood Maps
Confirm with
Hydraulic Models
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What was considered
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Structural• Levees / Floodwalls – protect overbank flood prone areas• Reservoirs – store floodwater• Diversions – route flows away from damage prone areas• Channel Modifications – alter bridges or widen channels• Groundwater Control Structures
Non-Structural• Raise/floodproof structures• Buyouts• Flood warning and preparedness
Measures Considered
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Screening Steps – Storage Example
1. Review open spaces along waterways2. Check for site conflicts (environmental, infrastructure, planned land use)3. Perform hydraulic modeling to determine potential flood reduction by storage areas4. Estimate benefit of storage using economic models5. Estimate cost to construct storage area based on general site conditions and
required features6. Compare project benefits to project costs7. Retain storage areas which indicate a possibility of positive net benefits for further
evaluation
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Identified Measures
FirstScreening
SecondScreening
Levees/ Floodwalls 40 31 4
New Storage or Modifications to Existing
Storage94 94 5
Bridge Modifications 51 33 1
Channel Improvements 1 1 0
Diversions 3 4 1
Dam Modifications 4 3 1
Below Grade Cut-Off Walls 2 2 1
Non-Structural Physical Measures
10 non-structural alternatives developed
Nature Based Features Consider for all recommended projects
Evaluation of Measures – Site Screening
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Measures were evaluated and screened based on:• Technical Feasibility• Cost Effectiveness• Environmental Acceptability
Remaining measures were grouped into alternative plans
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Measures to Alternatives
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Selecting Alternatives
Identify Problem
AreasEvaluate Solutions
Economically Justified
Tentatively Selected Plan
Maximize net benefits when selecting alternatives:• Improve life safety• Reduce economic damages
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What is the tentatively selected plan?
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Tentatively Selected Plan1 Structural Alternative:
• Lisle Levee ElevationNon-Structural Alternatives:
Branch Structure Count
West Branch 12East Branch 16Mainstem 14
Total 42
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Overview of Lisle Levee System
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East Branch DuPage River
Homes & Businesses
Anatomy of a Levee
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Background: How Levees Fail
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Existing Conditions: Lisle Levee
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• Remove vegetation and encroachments on and within 15 feet of the levee
• Increase height of levee to provide additional protection
• Flatten side slopes
• Install erosion control features
Lisle Levee Plan Components
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Nonstructural Recommendation
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Nonstructural Measures
Elevation Buyout or Relocation
(mandatory)
Dry FloodProofing
Wet FloodProofing
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Selection Criteria
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Example of Elevating a Home
Before
After
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Nonstructural Alternative
Branch Structure Count
West Branch 12East Branch 16
Mainstem 14Total 42
Additional structures may be added on the tributaries upon final economic analysis
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What to Expect as a Property Owner
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Input from notified individuals regarding measure selection incorporated
Late 2018 - Notice provided to eligible property owners
Final economic cost benefit analysis complete to confirm final recommended plan
From now through completion of this study (July 2019):
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What to Expect as a Property Owner
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Initial meeting to discuss next steps and benefits
Notice given to affected property owners (and any tenants)
Process implemented with input from owners
If the project is authorized and funded by Congress:
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Presenter
Imad SamaraUS Army Corps of Engineers
Chicago District
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Public Review Period Now – August 30, 2018
Feasibility Report Approval July 2019
Congressional Authorization *TBD
Congressional Appropriation *TBD
Design/Construction *TBD
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Next Steps
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We want your feedback
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How to Find the Report
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https://www.lrc.usace.army.mil/Missions/Civil-Works-Projects/DuPage-River/
Or internet search for: “Army Corps DuPage River Watershed”
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In-Person
E-mail: dupageriver@usace.army.mil
Mail: USACE, Chicago District231 S. LaSalle St, Ste. 1500Chicago, IL 60604ATTN: Planning Branch (DuPage River)
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or
Must be sent or postmarked by:September 22, 2018
How to Comment
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Questions
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https://www.lrc.usace.army.mil/Missions/Civil-Works-Projects/DuPage-River/