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Alternatives for Willow Creek Flood Mitigation StudyPresented by:
Anil Tangirala, PE, CFM, ENV SP | ms consultants, inc.
June 22, 2016
Presentation Overview
• Introduction
• Project Background
• Willow Creek Existing Flooding
• Project Goals
• Hydrologic and Hydraulic Analysis
• Alternatives for Flood Mitigation
• Modeling LID tools in HEC-RAS
• Summary and Conclusions
Flood Mitigation
• What is Flood Mitigation? Sustained action to
reduce or eliminate long term risk to people and property from flood hazards
• Structural Flood Mitigation Alternatives include: Upsizing culverts
Acquisition/demolition of repetitively flooded structures
Flood storage detention
Structural elevation
Where is the project?
What are the goals of this project?
• Reduce Congestions/Improve Safety
• Roadway Widening and Intersection Improvements
• Mitigate Flooding
What are the goals of this project?
• Reduce Congestions/Improve Safety
• Roadway Widening and Intersection Improvements
• Mitigate Flooding
What is the scope of the project?
• Phase I – Alternatives Evaluation Conduct existing System Hydrologic and Hydraulic Analysis
Identify Hydraulic Bottlenecks/Pinch Points in the Existing System
Develop Flood Mitigation Alternatives
Develop Planning level Cost Estimates
• Phase II – Detailed Design
• Project funded through federal earmark for transportation and flooding.
Project Background
Project Background
Willow Creek – Just DS of Sheetz Gas Station
Willow Creek –At Shepherd of the Valley Assisted Living Entrance Drive
Willow Creek at Sharrott Road
Willow Creek at Western Reserve Road
Willow Creek at Private Drive of Apartment Complex
Willow Creek at Private Drive for Daycare Center
Willow Creek at Hitchcock Road
Existing Flooding
Western Reserve Road near Sharrott Road
June 26, 2015
Flooding
Flooding on Western Reserve Road
June 23rd, 2015
Flooding
Flooding Near Metro Park
June 23rd, 2015
Flooding
June 2015 Rainfall in Youngstown, Ohio
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
1-Jun 4-Jun 7-Jun 10-Jun 13-Jun 16-Jun 19-Jun 22-Jun 25-Jun 28-Jun
PR
EC
IPIT
AT
ION
(IN
CH
ES
)
June 2015 Rainfall Data For Youngstown, Ohio
Historical Average Rainfall (inches) Total Recorded Rainfall (inches)
5yr - 10yr Storm
Event
1yr - 5yr Storm
Event
Flooding near Market Street
ODOT SR-7 Hydraulic Study
• Flooding also occurs north of CR 32 along the west side of the SR-7 roadway and within the Antone’s Banquet Centre parking area during moderate to heavy storms.
• Several culvert improvements proposed as part of this study conducted by ODOT.
ODOT SR-7 Hydraulic Study
ODOT SR-7 Hydraulic Study
Existing Conditions Hydrologic Analysis
• Hydrologic Analysis using USACE HEC-HMS
• Sub-basins delineations
• Time of concentrations and curve numbers
• Reach Routing – Muskingum Cunge
• Boundary Conditions – ODOT SR-7 Study
Drainage Basins
Existing Hydrologic Analysis Results
Flow Change Location
Peak Discharge (cfs)R
EC
UR
RE
NC
E
Sheetz CMP Shepherd of the
Valley Assisted
Living Entrance
Sharrott
Road
Western
Reserve Road
Private
Drive
(Apartment
Complex)
Private Drive
(Daycare
Center)
Hitchcock
Road
2-YEAR 188.5 191.7 198.5 198.5 208.6 227.3 229.6
5-YEAR 275.4 280.1 289.9 289.9 204.6 334.5 339.1
10-YEAR 342.0 348.0 360.6 360.6 379.5 419.2 426.2
25-YEAR 428.7 436.7 453.3 453.3 487.1 532.3 543.2
50-YEAR 496.8 506.7 526.6 526.6 556.5 622.7 637.0
100-YEAR 564.2 575.9 599.0 599.0 634.3 713.3 731.6
Existing Conditions Hydraulic Analysis
• Hydraulic Analysis using USACE HEC-RAS
• Cross-section and Channel Geometry
• Roughness- Channel and Overbank Manning’s
• Peak Discharges
• Boundary Conditions- Downstream
Willow Creek Hydraulics
Existing Conditions Flood Profiles
Existing Conditions Level of ServiceCulvert Location Culvert Size and Type Approx. Culvert Opening
Area (Sq. Ft.)
Existing Level of Service
Shepherd of the
Valley Driveway
3 x 6’x4.5’ Elliptical
CMP Culverts
63.63 sq. ft. 2-year Storm Event
Sharrott Road 2 x 48” Circular CMP
Culverts
25.14 sq. ft. <2-year Storm Event
Western Reserve
Road/CR-32
1 x 12’ x 5’ Stone
Abutment Structure
60.00 sq. ft. 2-year storm event
Private Drive Bridge Wooden planks on
Steel I-beam Bridge
40.43 sq. ft. <5-year Storm Event
Private Daycare
Bridge
2 x 5.5’x4’ Elliptical
CMP Culverts
34.56 sq. ft. 2-year Storm Event
Hitchcock Road 14’ Span Slab Bridge 84.06 sq. ft. 100-Year Storm
Event
Proposed Condition Level of Service Goals
• All water crossings to be mitigated to atleast meet LOS requirements based on Mahoning County Regulation.
• One driveway is a an entrance to a Old Age Home and classifies as a “Critical Facility”
• Higher level of protection planned for the Critical Facility
• Under Executive Order 11988, Floodplain Management, Federal agencies funding and/or permitting critical facilities are required to avoid the 0.2% (500-year) floodplain or protect the facilities to the 0.2% chance flood level.
Flood Mitigation Alternatives
• Several Alternatives developed and evaluated
• Alternative 1a – Culvert Upgrades
• Alternative 1b – Culvert Upgrades and new Driveway
• Alternative 2 – Diversion
• Alternative 3 - Detention
Alternative 1a Culvert Upgrades
Alternative 1a Culvert Upgrades
Culvert Location Existing Culvert Size
and Type
Proposed Culvert Size
and Type
Shepherd of the Valley
Driveway
3 x 6’x4.5’ Elliptical CMP
Culverts
22’x4’ Box Culvert
Sharrott Road 2 x 48” Circular CMP
Culverts
13’x4’ Box Culvert
Western Reserve
Road/CR-32
1 x 12’ x 5’ Stone
Abutment Structure
13’x4’ Box Culvert
Private Drive Bridge Wooden planks on Steel
I-beam Bridge
Remove Bridge and
Extend 13’x4’ Box
Culvert from Western
Reserve Road/CR-32
Private Daycare Bridge 2 x 5.5’x4’ Elliptical CMP
Culverts
12’x5’ Box Culvert
Alternative 1b Culvert Upgrades & New Driveway
Alternative 1b Culvert Upgrades
Culvert Location Existing Culvert Size
and Type
Proposed Culvert Size
and Type
Shepherd of the Valley
Driveway
3 x 6’x4.5’ Elliptical
CMP Culverts
22’x4’ Box Culvert
Sharrott Road 2 x 48” Circular CMP
Culverts
13’x4’ Box Culvert
Western Reserve
Road/CR-32
1 x 12’ x 5’ Stone
Abutment Structure
13’x4’ Box Culvert
Private Drive Bridge Wooden planks on Steel
I-beam Bridge
Remove Bridge
Private Daycare Bridge 2 x 5.5’x4’ Elliptical
CMP Culverts
12’x5’ Box Culvert
Alternative 2 – Diversion
Modeling LIDs in HEC-RAS
• Pressurized Pipe Flow can be modeled in HEC-RAS
• Steady and Un-Steady Flow
• Diversion pipe can be modeled by using cross-sections to model the bottom and LID to model top of the pipe
• Steady Flow uses standard energy equation and Un-Steady uses Priessman Slot Theory and Water Hammer Equations.
Modeling LID in HEC-RAS
Calculation of Transition Losses
Applications for modeling LIDs in HEC-RAS
• Long Culverts
• Tunnels
• Diversion Pipes/Conduits
• Culverts with bends-Ability to include minor losses.
Alternative 2 - Diversion
Culvert Location Existing Culvert Size
and Type
Proposed Culvert
Size and Type
Shepherd of the Valley
Driveway
3 x 6’x4.5’ Elliptical
CMP Culverts
22’x4’ Box Culvert
Sharrott Road 2 x 48” Circular CMP
Culverts
11’x4’ Box Culvert
Western Reserve
Road/CR-32
1 x 12’ x 5’ Stone
Abutment Structure
11’x4’ Box Culvert
Alternative 3 – Detention
Alternatives Pros & Cons
Alternative Description Advantages Disadvantages
Hydraulic Alternative 1A Replacement of undersized
culverts and extension of
Western Reserve Road
Culvert
• Mitigates Flooding
• No major diversion or
detention
• Will require the
extension of the
Western Reserve
Culvert and
earthwork to cover
the new structure
Hydraulic Alternative 1B Replacement of undersized
culverts and removal of the
Private Drive downstream of
Western Reserve Road
• Mitigates Flooding
• Provides property owner
access from Western
Reserve Road
• Prevents frequent
overtopping of private
bridge
• Restricts access
between property
owners.
Alternatives Pros & Cons
Alternative Description Advantages Disadvantages
Hydraulic Alternative 2B Replacement of undersized
culverts and diversion from
Sharott Road to the east side
of Hitchcock Road
• Only requires upsizing of
two culverts
• Does not solve the flooding
at the Private Drive
culvert
• Will require the
installation of the new 48”
diversion storm sewer
Hydraulic Alternative 3 Replacement of undersized
culverts and construction of a
detention basin upstream of
the Shepherd of the Valley
culvert
• Reduces peak discharges
downstream of the basin
• Not enough detention, still
requires upgrades
• Significant Environmental
Permitting
Floodplain Permitting
Alternatives Opinion of Probable Costs
Alternative Preliminary Costs
Alternative 1A $1,242,600
Alternative 1B $1,118,800
Alternative 2A $1,657,800
Alternative 2B $1,771,500
Alternative 3 $1,526,300
Conclusions
• Existing System evaluation helps us understand pinch points in the system
• H&H useful in analyzing alternatives. Useful tools available within HEC-RAS to model alternatives
• Coordination with other projects essential
• Environmental Permitting Requirements
