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Johnstown Redevelopment Authority (JRA) is responsible
for daily maintenance activities and, most importantly,
for maintaining the long-term integrity of five Flood
Protection Projects. In general terms, these projects
were constructed to reduce flooding hazards by increasing
the flood conveyance capacity or flood management behavior
of the existing stream. These projects consist of several
component features such as concrete channelization, debris
basins and concrete weirs and debris racks. The JRA is
responsible for all maintenance activities associated
with the individual features for each Flood Protection
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CONCRETE
CHANNEL - CHANNELIZATION
In general terms, channelization refers to the straightening
and/or widening of the existing stream channels in an
attempt to reduce flooding hazards to the communities
in proximity to the stream. It is recognized that a certain
amount of loss of habitat goes along with channelization,
however death and destruction resulting from flooding
has created a higher priority in these already urbanized
areas. The use of channelization to control flooding has
been historically referred to as "stream improvement."
All the streams entering the City have been channelized.
This was done in an attempt to improve the hydraulic capacity
(ability to move a volume of water) of the streams to
move floodwaters through an area. For the five Flood Protection
Projects this was done using a number of different approaches,
including: widening the stream channel so it would hold
more water, building flood walls along the edges of the
stream to hold the flood flow in the channel and thus
protect the surrounding communities from death and destruction
and/or reducing the roughness of the stream channel by
constructing a smooth channel out of concrete.
Across the five Flood Protection
Projects several different types of Concrete Channelization
are in place:
1. Grouted Rip Rap Channel
2. Trapezoidal Concrete Channel
3. Rectangular Concrete Channel
All of these channel sections
serve the same general purpose, to protect the surrounding
community from the hazards of flooding.
This Feature Is Located
On All Projects
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(Photos of Solomon
Run FCP)
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DEBRIS
RACK
A Debris Rack is a structure that is placed across the
concrete channel to allow water to flow through while
trapping debris (tree limbs, leaf accumulations, miscellaneous
trash and rubbish, etc) carried by the channel. A Debris
Rack is intended to keep the channel free of any objects
that may decrease its ability to function properly.
This Feature Is Located On The Sams Run &
Elk Run Projects
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(Photo of Sams Run FCP) |
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DEBRIS
BASIN
Debris Basins are constructed at the beginning of a Flood
Protection Project to establish an initial buffer area
that reduces the impact of debris collected upstream by
high flows. These basins are formed by earthen or concrete
dams constructed across the entrance of the channel to
create an area of ‘calmer’ flow. This stilling
area allows sediment, rocks, boulders and other debris
to settle out of the flow so that they will not damage
or obstruct the downstream facilitates.
This Feature Is Located On The Solomon Run, Sams
Run & Elk Run Projects
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(Photo of Solomon Run FCP –
Falls Run)
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CONCRETE
WEIR
The Concrete Weirs are a component of the Debris Basins.
The Concrete Weir is what creates the Debris Basin. They
are designed to sufficiently constrict the flow to create
a deeper pool behind itself to allow debris to settle
out. The Concrete Weirs on the Solomon Run Flood Protection
Project are made out of concrete. For the Elk Run Flood
Protection Project, the weir is an earthen dam (See Outlet
Structure below). A combination concrete and earthen weir
is located on the Sams Run Flood Protection Project.
This Feature Is Located On The Solomon Run, Elk
Run & Sams Run Projects
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(Photos of Solomon Run FCP )
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OUTLET
STRUCTURE AND CHANNEL
The Outlet Structure feature located on the Elk Run Flood
Protection Project serves the same function as the Weirs
located on the Solomon Run and Sams Run Flood Control
Projects. The Outlet Structure on the Elk Run Project
was constructed to create the Elk Run Debris Basin. The
Outlet Channel feature located on Elk Run serves to carry
flows from the Outlet Structure to the concrete channelized
sections of the Project.
This Feature Is Located On The Elk Run Project
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(Photos of Elk Run FCP) |
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