Main Street Dam Feasibility Study
description
Transcript of Main Street Dam Feasibility Study
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MAIN STREET DAM REMOVAL
FEASIBILITY STUDY20
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ACKNOWLEDGEMENTS
COLUMBUS DOWNTOWN DEVELOPMENT CORPORATION
Guy Worley, CEO
Amy Taylor, COO
Milt Lewis, Director of Construction Services
CITY OF COLUMBUS
Dax Blake, PE, Administrator, Division of Sewerage and Drainage
Mike Griffi th, PE, Division of Sewerage and Drainage
Erin Miller, Environmental Steward
STANTEC
Bryon Ringley, PE, Principal
Scott Peyton, PE, Senior Associate
Travis White, PE, SI, Senior Project Engineer
Brad Rodgers, PE, CHMM, Senior Associate
Cody Fleece, Senior Ecologist
Rich Williams, PhD, PE, Senior Geotechnical Engineer
Jenny Rytel, PG, Geologist
Mary Murphy, Administrative Assistant
MSI DESIGN
Keith Myers, FASLA, Principal
Darren Meyer, RLA, Associate Principal
Andrew Overbeck, AICP, Urban and Regional Planner
Aron Fraizer, ASLA, Associate
Charles Benick, Project Designer
RESOURCE INTERNATIONAL
Michelle Eckels, CPG, Director of Environmental Services
Mark Ward, PS, Survey Manager
ASC GROUP
Shaune Skinner, President
Al Tonetti, Cultural Resource Specialist
COLDWATER CONSULTING
Kristen Risch, Senior Restoration Specialist
SHELLEY, METZ, BAUMANN, HAWK
Jon Beier, PE, LEED AP BD+C
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02 acknowledgements and table of contents
04 executive summary
06 planning context
08 recent investment
10 river evolution
12 feasibility study
14 natural channel design
16 concept plan
26 implementation
TABLE OF CONTENTS
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RIVERFRONT RENAISSANCE
Columbus is in the midst of a riverfront renaissance. Beginning
with North Bank Park in 2004, and continuing with the opening of
the Scioto Mile and the Scioto Audubon Metro Park, Downtown’s
riverfront has been transformed. The 2010 Downtown Columbus
Strategic Plan built on this momentum by proposing the removal
of the Main Street Dam and the creation of a greenway along the
Scioto River as the beginning of a new green corridor through the
heart of the city. The Scioto Greenways Feasibility Study , funded
by the Columbus Downtown Development Corporation and the
City of Columbus, explores the environmental, engineering, and
land planning challenges associated with removal of the dam. The
study provides a technical solution that meets these challenges
and shows how a naturalized river corridor and parkland will enable
Downtown to truly embrace the Scioto River.
A NEW URBAN RIVERFRONT
The downtown portion of the Scioto River is currently an overly-
wide, slow-moving pool of sediment-laden water, due to the Main
Street Dam. Removing the dam would allow the water course to be
narrowed and green space to be added along its edges. Building
on the public and private investment in The Scioto Mile, the urban
riverfront would be expanded with 33 acres of new green space
that connects Downtown to the river and the Scioto Peninsula. The
Master Plan Concept includes plaza and event spaces that enhance
the Scioto Mile. Phase one improvements focus on new greenways
on both sides of the Scioto River that would tie into the existing
Downtown and regional bikeway system and allow for new access
at the river level. The greenway transitions to a naturalized river edge
condition designed to restore river habitat and withstand fl ood events.
A RESTORED RIVER
In addition to enhancing the public realm, removing the Main Street
Dam allows for the implementation of a natural channel design that
restores river habitat. Today, the downtown portion of the Scioto
River is designated as a Modifi ed Warm Water Habitat by the Ohio
EPA due to the lower expectations for aquatic habitat and biological
success in this area. The Scioto River can attain a higher aquatic
habitat use if the physical impairments are removed and the natural
form and function of the river is restored. A healthier river, along
with new pathways and recreational access, will bring people to the
EXECUTIVE SUMMARY
riverfront and connect the neighborhoods and districts along the
river corridor.
STRONGER CONNECTIONS
In addition to strengthening the connection between Downtown
and the Scioto Peninsula, the removal of the Main Street
Dam will better link The Ohio State University to Downtown
Columbus. With the removal of the 5th Avenue Dam at OSU on
the Olentangy River well underway, there will be a free-fl owing,
navigable river from the campus area through Downtown
Columbus. These two projects set the stage for the exploration
of removing or modifying other dams upstream on the Olentangy
River, with the complete realization creating a naturalized river
corridor from Highbanks Metro Park to the Scioto Audubon
Metro Park through OSU and Downtown. This 16.5-mile green
link would be unmatched in any major U.S. city today.
UNLIMITED TRANSFORMATIVE POTENTIAL
Improving the health of the river increases its value to the
community, contributing to a more prosperous, competitive
metropolis for the 21st century. The removal of the Main Street
Dam is an important fi rst step in carrying out the vision of
a restored river corridor through Downtown Columbus and
beyond.
• Build on recent park investments
• Reduce river width
• Clean and restore river habitat
• Enhance greenway connections
• Improve access to river
• Create economic value and spur redevelopment
• Improve linkages between downtown and Scioto
Peninsula
• Work within existing 100 year fl oodplain
PROJECT GOALS
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“Building on the Scioto Mile, this new urban riverfront downtown could be expanded with 33 acres of new green space.”
BEFORE
AFTER - MASTER PLAN CONCEPT
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EARLY HISTORY
Throughout Columbus’ history, the Scioto River has been
evolving. In place by the mid-1800s, the original timber dam
was built to provide water for the feeder canal that connected
the Scioto River to the Ohio and Erie Canal. Over this period,
the river channel has been constantly changing, along with
the city. Smaller river channels were fi lled in, islands were
removed and the river course was altered to accommodate
bridges, railroads, industry and other development.
RESHAPING THE RIVER
The most signifi cant changes to the river corridor occurred
after the fl ood of 1913. The fl ood destroyed the original
timber dam and the river width narrowed closer to its natural
watercourse. The resulting mud-fl ats that were exposed
created an unsightly appearance in Downtown. The Main
Street Dam was built in 1921 in order to create a more
aesthetically pleasing riverfront, and resulted in a wider river.
This river pool was built in concert with other Civic Center
riverfront improvements, including City Hall. The Main Street
Dam was altered in 1929 to add another foot and half in height
to the dam that created the river width of the Scioto River
today.
THE RIVER TODAY
Over time, the Main Street Dam has prevented the passage
of sediment and limited the navigability of the Scioto River.
In the late 1980s, efforts were made to dredge the river to
deepen the channel and allow for water craft use, but the
river soon deposited more sediment and further efforts were
not undertaken. Additionally, by this time the original 1920s
improvements had begun to age with the concrete revetments
and balustrade along the river edge crumbling into the river.
As part of the improvements to North Bank Park and the
Scioto Mile, this revetment condition has been removed and
the river edge has been naturalized. The balustrade along
Civic Center Drive has also been restored and renovated.
RIVER EVOLUTION
REMAINS OF THE FEEDER CANAL
INDUSTRY ALONG THE SCIOTO RIVER
DAMAGE FROM THE 1913 FLOOD
THE MAIN STREET DAM TODAY
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• Feeder Canal and Sluice
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• Timber Dam
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• Scioto Peninsula Filled In Remaining Islands
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• Post - 1913 Flood Condition
• Timber Dam Destroyed
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• Wider Main Street Dam built to replace
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• Taller Main Street Dam
• Current River Width 07
“Since the founding of Columbus the Scioto River has been evolving and changing.”
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LINKING DOWNTOWN AND NEIGHBORHOODS
From Worthington to Downtown Columbus, seven low head dams
interrupt the natural fl ow of the Olentangy River. These dams
impair aquatic habitat, degrade water quality, limit recreational
opportunities, and create a safety hazard. The 2010 Downtown
Columbus Strategic Plan advanced a strategic vision for removing
these dams to create a 16.5 mile greenway corridor that connects
Scioto Audubon Metro Park and Downtown to numerous
neighborhoods and High Banks Metro Park to the north. Cleaning
the rivers and removing low head dams would restore the natural
river course, reintroduce river habitat as a tranquil amenity, and
create more green space and recreational opportunities. This
catalytic idea builds on the recent investment and current plans to
restore river health. With North Bank Park, the Scioto Mile, and the
Scioto Audubon Metro Park, nearly all of the downtown riverfront
park system has been remade into a world-class park destination.
However, this investment is incomplete until the river health is
restored. The City of Columbus has taken the fi rst step toward a
healthy river with its efforts to implement a $2.5 billion wet weather
management program to reduce the occurrence of combined sewer
overfl ows. The 5th Avenue Dam removal represents the fi rst step in
restoring the natural river course and enhancing habitat along this
corridor. With the removal of the Main Street Dam, the initial link in
this river greenway system will be created between The Ohio State
University and Downtown Columbus. In time, this model can extend
north along the river corridor, connecting neighborhoods to the river
and to Downtown Columbus.
COMMUNITY CONNECTIONS
HIGHBANKS METRO PARK
THE OHIO STATE UNIVERSITY
DOWNTOWN COLUMBUS
SCIOTO AUDUBON METRO PARK
• Connected – links neighborhoods, communities, and
recreational opportunities
• Healthy – promotes physical activity and bike
commuting in a beautiful and engaging environment
• Smart – provides educational opportunities for the
entire community to learn about the importance of
protecting our river systems
• Sustainable – restores the river habitat and increases
biodiversity
• Prosperous – raises property values adjacent to the
greenway corridor and encourages reinvestment
COMMUNITY BENEFITS
Sc
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Ohio State University
5th Avenue Dam
Worthington
Highbanks Metro Park
Scioto Audubon Metro Park
Clintonville
Downtown Columbus
Main Street Dam
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“The Scioto-Olentangy Greenway Corridor would create a 16.5 mile green link through the heart of the city.”
STUDY AREA
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RECENT IMPROVEMENTS
The RiverSouth area and Downtown Columbus riverfront have
seen hundreds of millions of dollars of public and private
investment over the past decade. In addition to North Bank Park
and the Scioto Mile, surrounding street infrastructure has been
improved to allow for two-way traffi c, and there are two new
bridges across the Scioto River. New residential development at
the Annex at River South has also come online to complement
the existing residential properties Downtown by providing
affordable rental options. The renovated Lazarus Building offers
700,000 square feet of offi ce space and prime street-level retail
in a LEED Gold certifi ed building.
DEVELOPMENT OPPORTUNITIES
The Main Street Dam removal project will capitalize on these
investments and be the catalyst for further redevelopment.
Across the country, dam removal and river restoration projects
have been shown to enhance the economic value of property,
businesses and communities. This new 33-acre greenway in
the heart of Downtown will draw people to the waterfront and
encourage interaction at the river level. Building on the recent
completion of two new bridges across the Scioto River that
provide better access to COSI and other attractions, this new
riverfront greenway will further help the west bank of the river
to embrace the riverfront and Downtown, acting as a catalyst
for redevelopment of vacant and underutilized property on the
Scioto Peninsula and East Franklinton.
RECENT AND FUTURE INVESTMENT
• The 33 acre greenway will increase private
development and attract hundreds of thousands of
visitors annually
• Surrounding this revitalized river and greenway is
nearly 100 acres of vacant and underutilized land
that is primed for redevelopment, especially on the
Scioto Peninsula and East Franklinton.
• The Main Street Dam removal project will support
as many as 350 new jobs in the region
NORTH BANK PARK
THE SCIOTO MILE
MAIN STREET BRIDGE
SCIOTO AUDUBON METRO PARK
ECONOMIC IMPACT
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MAIN STREET
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“The Main Street Dam Removal project seeks to build on the
investment and momentum along the Downtown Columbus riverfront”
RECENT INVESTMENT
POTENTIAL FUTURE REDEVELOPEMNT
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OBJECTIVES
The Main Street Dam Removal Feasibility Study had four
primary objectives:
• Develop a thorough understanding of the river and the
land and structures within and around it.
• Determine the potential environmental and engineering
issues involved in removing the dam, particularly the
impact on the 100 year fl oodplain
• Develop a concept plan for the river channel that restores
the natural river course and improves water quality
• Expand the concept plan to show how the reclaimed
public land on either side of the river could be reused as
urban park space
ADDRESSING THE CHALLENGES
Throughout this project numerous issues were addressed:
• Historic Preservation: Study outlined changes made to
the Scioto River over time and determined that the Main
Street Dam is not in the Civic Center Historic District,
although the project is subject to Section 106 of the
National Historic Preservation Act of 1966.
• Ecology: Determined that the dam is inhibiting the river
from reaching its potential use attainment designation
of Warm Water Habitat, and that dam removal and river
restoration will improve habitat for native fi sh and mussel
species that should reside in the Scioto River.
• Hydrogeology: Found that there is a relationship between
FEASIBILITY STUDY
a permeable gravel aquifer and the Scioto River that
both discharges and receives water from the river.
• Sediments: Sediment samples contained some con-
taminants above residential levels. Ohio EPA indicates
preliminarily that these contaminants may not need to
be removed but could be reused under certain condi-
tions.
DEVELOPING THE CONCEPT PLAN
With this baseline information determined, a Concept Plan
for the dam removal and addition of parkland was created
to demonstrate what could be done with the narrowed river
channel in terms of new open space and restored river habitat
in Downtown. This plan adds 33 acres of additional green
space to Downtown and offers a new pedestrian linkage be-
tween Downtown and COSI in addition to enhanced river rec-
reation opportunities and extensive new pathways and river
viewpoints. The proposed dam removal, restoration design,
and park improvements were then modeled and compared to
existing conditions along the river. No rises in one-percent an-
nual chance fl ood elevations will occur. The Standard Project
Flood will remain contained within the fl oodwall. Average an-
nual river elevations will decrease by approximately seven feet
immediately upstream of the former dam location. Likewise,
the structures and bridges within the river corridor were also
assessed and changes recommended in order to mitigate
impacts of the river lowering.
CONCERNS RESPONSES
1. Utility Crossings will be exposed by lower water
levels and impacted by increased scour.
2. Combined Sewer Overfl ow odor will increase due
to lower water levels.
3. Piers of existing bridges will be exposed by drop-
ping the water level.
4. Foundations near river for OSIS, fl oodwall, and
adjacent buildings could be damaged by the
lowering of the river.
5. Flood levels could be adversely impacted by
removing the dam.
1. Proposed river bed will maintain cover above
existing utility crossings.
2. Existing lines will be extended to ensure that the
submerged condition remains, containing odor.
3. Bridge piers will either be on the banks of the new
river, or will have extended caps on piers to ad-
dress concerns.
4. Groundwater in the area feeds the river and is
currently cut-off by the fl oodwall. The groundwater
conditions today will not be altered.
5. The 100 year fl oodplain extents are not altered
as part of this project, allowing the river and park
system to handle fl ood events.
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“With the removal of the Main Street Dam the Scioto River will be narrowed by
nearly half and Downtown Columbus will gain 33 acres of new riverfront park land.”
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RIVER NARROWINGNATURAL CHANNEL DESIGN
MODELING OF THE CONCEPT
As part of the Feasibility Study, the impact of the dam removal
and the implementation of a natural channel design for the Scioto
River were assessed. Modeling of the proposed conditions
resulted in no rises in the 1% annual chance of fl ood elevations
and found that the Standard Project Flood will remain contained
within the fl oodwall. In general, the 100 year fl oodplain extents are
not altered as part of this project. In certain areas, especially in
front of COSI, it actually improves slightly (see diagram at right).
IMPACT ON THE RIVER LEVEL
While the impact of the dam removal is greatest immediately
upstream of the former dam location, resulting in a seven foot
decrease in the water surface elevation based on average annual
fl ow conditions, the entire river corridor will see a decrease
in channel width. The sections at right illustrate this change
in channel width and the added greenway (based on average
annual fl ow conditions).
HABITAT RESTORATION
Removing the dam and implementing a natural channel design
will result in an increase in ambient dissolved oxygen, a reduction
in low fl ow water temperatures, and an improvement of habitat
diversity and aquatic habitat. The natural channel design will also
provide the necessary substrates and fl ow regimes needed for the
recolonization of fi sh and mussel species that were once found
in this segment of the Scioto River. The dam removal will also
allow these species to migrate upstream, increasing the diversity
of those aquatic communities. Due to these improvements, an
increase in the Qualitative Habitat Evaluation Index from the Ohio
EPA is expected for this segment of the Scioto River.
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SECTION 1
SECTION 2
SECTION 3
Existing Channel
Proposed Channel
CHANNEL WIDTH
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Existing 100 year fl oodplain
Proposed 100 year fl oodplain reduction
FLOODPLAIN WIDTH
• Recreates and restores a more natural channel for the
Scioto River
• Has a positive impact on water quality, river health and
aquatic habitat
• Provides for the recolonization of native fi sh and
mussel species
• Allows for upstream migration, increasing the diversity
of these aquatic communities.
ENVIRONMENTAL BENEFITS
• Existing crossing = 495 feet
• Proposed crossing = 250 feet
• Width reduction = 245 feet
• Existing crossing = 495 feet
• Proposed crossing = 245 feet
• Width reduction = 250 feet
• Existing crossing = 570 feet
• Proposed crossing = 270 feet
• Width reduction = 300 feet
SECTION 1
SECTION 2
SECTION 3m
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570’ Existing Crossing
270’ Proposed Crossing
570’ Existing Crossing
495’ Existing Crossing
245’ Proposed Crossing
495’ Existing Crossing
250’ Proposed Crossing495’ Existing Crossing
FEDERAL
COURTHOUSE
BICENTENNIAL
PARK
VETERANS
MEMORIAL
COSI
SCIOTO MILE
PROMENADE
HEALTH
DEPARTMENT
SITE
SCIOTO
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SCIOTO
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SCIOTO
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SCIOTO
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SCIOTO
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SCIOTO
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495’ Existing Crossing
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EXISTING
PROPOSED
EXISTING
PROPOSED
EXISTING
PROPOSED
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INTRODUCTION
With the engineering parameters of the Main Street Dam Remov-
al defi ned, the project team created a Master Plan Concept for
the narrowed river, restored river edge and adjacent greenway.
The implementation of a natural channel design allows for the
creation of approximately 33 acres of ground that can be used
to meet fl oodplain requirements, restore river habitat and create
greenway connections.
New pathways on both sides of the Scioto River tie into the
existing downtown and regional bikeway system and allow for
interaction and access at the river level. The park pathway and
plaza areas transition to naturalized river edge condition that is
designed to withstand fl ood events. The greenway will link into
the existing bikeway system with bike paths and landscaped
park areas. This greenway corridor will connect The Ohio State
University to Downtown Columbus and provide recreational
opportunities such as cycling, canoeing and kayaking. Taken
together, these improvements will create an opportunity for the
public to experience and interact with the river in a more natural
state.
The Master Plan Concept seeks to build on recent park invest-
ment along the downtown riverfront from North Bank Park to
the Scioto Audubon Metro Park. Elements of the Scioto Mile
will be enhanced with new plaza and event spaces, especially
at the Town Street Prow that will have a two-level overlook. On
the west side of the river, an extension of the plaza and lawn in
front of COSI will create an expanded event space. Building on
the theme of connections, a proposed pedestrian bridge will
directly connect COSI and the Scioto Peninsula to the Scioto
Mile Promenade and Downtown Columbus helping to visually
and physically link these two nodes of activity.
With these improvements, Downtown will no longer turn its back
on the Scioto River. Instead, it will be able to use the river for
recreation, admire it for its natural beauty and celebrate it as the
“central park” of Downtown Columbus.
MASTER PLAN CONCEPT
PROJECT PHASING
To enable the effi cient implementation of this project, the pro-
posed Master Plan Concept improvements have been divided
into two phases. The Master Plan diagram at right highlights
major plan components under each phase.
Phase One components focus on dam removal, river channel
formation, river restoration and associated greenway and bike
path components. Phase Two components include event and
plaza spaces, additional hardscape and landscape features and
fountains, and a pedestrian bridge across the Scioto River con-
necting the Scioto Peninsula to the Scioto Mile Promenade. Ren-
derings of all Phase One components are shown on subsequent
pages of this report. An Implementation section follows that
outlines the preliminary estimate of probable cost for Phase One.
• Removal of concrete low head dam south of the Main
Street Bridge
• Removal of accumulated sediment behind dam
• Restoration of a more naturalized and narrower river
course and channel topography with the creation of
pools, riffl es, and glides that improve river fl ow and
habitat.
• Creation of a stabilized riveredge and naturalized
river bank using bioengineering methods – no riprap
or concrete walls with the exception of limited, target
areas for public access to the river edge.
• Construction of a greenway system with bike paths,
park space, and connections to existing public parks
and amenities.
PHASE ONE IMPROVEMENTS
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“Downtown Columbus will no longer turn its back on the Scioto River. Instead, people will be able to use it for recreation, admire it for its natural beauty and celebrate it as
the ‘central park’ of Downtown Columbus.”
PHASE ONE COMPONENTS
1. Restored River Channel: Reconfi gured river channel
sculpted with pools, riffl es and glides to create a more
natural and healthy river environment, supporting a diverse
aquatic habitat.
2. Restored River Edge: Bio-engineered, stabilized and
vegetated river edge with native plant material and riparian
habitat. The river edge transitions from native plantings to
manicured parkland upslope of the leisure trail.
3. Leisure Trail: Continuous 12-foot-wide leisure trail on both
the east and west banks that is integrated with the Scioto-
Olentangy Bikeway and larger regional bike trail system.
4. Scioto Quay: Lower level walkway along river’s edge. The
quay brings people to the river and provides a link in the
trail system.
PHASE TWO COMPONENTS
5. Town Street Prow: Two-level plaza space that preserves
the existing Town Street Prow and creates a lower-level
overlook to the river and West Bank. The two levels are
connected by a grand stair along the south edge of the
existing Prow.
6. East Landing: Urban plaza and event space that provides a
connection between Downtown Columbus, the Scioto Mile
Promenade and the pedestrian bridge.
7. Event Plaza and Lawn: Extension of the plaza and lawn
space in front of COSI to create a venue for expanded
festivals, events and exhibits.
8. Pedestrian Bridge: Signature bridge for pedestrians con-
necting COSI and the Scioto Peninsula to the Scioto Mile
Promenade and Downtown Columbus.
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“This project has such tremendous potential to transform the image of our city.”
- public comment
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“Removing the dams will help clean up the river and improve the experiences throughout the neighborhoods along the river corridor into Downtown Columbus and
the Scioto Audubon Metro Park.”- public comment
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“This idea is groundbreaking. It returns the river to its natural fl ow and uses a sustainable
model for fl ood management.”- public comment
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“Ohio means ‘beautiful river.’ As the state capital, Columbus could be the showcase of what a natural, beautiful river looks like.
I would dedicate my life to making this idea a reality.”- public comment
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WHAT WILL IT COST
Based on the concept developed as part of the Feasibility Study,
a preliminary estimate of probable cost was prepared. Below is
the estimate for Phase One improvements, which is divided into
several project categories:
• Existing Conditions / Site Preparation and Dam Removal:
Involves project mobilization and the demolition of the Main
Street Dam.
• River Restoration: includes all necessary earthwork as part
of removing sediment and adding necessary fi ll to create
the adjacent parkland, the creation of the new river channel,
and the restoration of the naturalized river edge itself.
• Utility Work: includes required extensions and protection of
existing utilities that are exposed as part of the lowering of
the river level.
IMPLEMENTATION
• Greenways (Transportation): includes all pathways and bike-
paths and associated hardcape improvements.
• Greenways (Park Space): includes all park space improve-
ments adjacent to pathways and bikeways.
•
MOVING FORWARD
The Main Street Dam Removal will require a coordinated effort
among multiple regulatory agencies and the private and public
sectors to achieve implementation. This new 33-acre green
space will improve the health of the river and increase its value
to the community. Building on recent park investment and
planned improvements, this new “central park” will be a green
link that both creates a more cohesive Downtown and connects
it to the wider city. Taken together, these improvements to the
river corridor will help the city become a more prosperous and
competitive metropolis for the 21st century.
Existing Conditions / Site Preparation
Dam Removal
River Restoration
Utility Work
Greenways (Transportation)
Greenways (Park Space)
River Restoration
$20,194,304
57%
Utility Work
$3,995,493
11%
Greenways (Transportation)
$3,878,757
11%
Greenways (Park Space)
$4,109,125
12%
Existing Conditions / Site Preparation
$3,003,212
8%
Dam Removal
$325,415
1%
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