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#Post#: 2496--------------------------------------------------
Latest update from NYPA on Dam repairs
DIR By: Michael Caswell
Date: November 9, 2023, 11:08 am
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HTML https://www.nyscanalintegrity.org/royalton
#Post#: 2530--------------------------------------------------
Re: Latest update from NYPA on Dam repairs
DIR By: Doug K
Date: February 5, 2024, 7:46 am
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And the local Lockport Press has the better explanation...
Shane Mahar explained that over decades of “deferred
maintenance” by the state, roots from trees and other vegetation
growing along the embankments have played a significant part in
causing seeps in the ground along that stretch of the canal.
“Embankments along the canal were never intended to have trees
and vegetation growing on them,” Mahar said. “That’s not how
they were designed and that doesn’t follow dam safety practices
set by the Army Corps of Engineers and others.”
The seeds of the program were planted around 2017 when New York
Power Authority assumed responsibility for the Canal
Corporation.
And this statement that still supports this NEW Public Safety
effort by NYPA and the New York State Canal Corporation
“As stewards of the historic Erie Canal, it is incumbent upon us
to ensure that the waterway’s infrastructure continues to
operate safely for generations to come,” Canal Corporation
Director Brian Stratton said. “This project in Royalton and
future investments in the earthen embankments that carry the
canal high above surrounding communities are integral components
of maintaining the longevity of the canal system.”
HTML https://www.lockportjournal.com/news/state-undertaking-erie-canal-patchwork-in-royalton/article_33e67160-8599-11ee-82e3-bf5a461d8941.html
#Post#: 2531--------------------------------------------------
Re: Latest update from NYPA on Dam repairs
DIR By: Michael Caswell
Date: February 5, 2024, 9:10 am
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Is the NYPA suggesting that this is an alternative to lopping
all the vegetation off the slopes? I'm sure a few will be
getting their hopes up. You know, those 'shade' fiends!
#Post#: 2532--------------------------------------------------
Re: Latest update from NYPA on Dam repairs
DIR By: Doug K
Date: February 5, 2024, 9:49 am
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No, this "cut-off wall" solution WAS already investigated as a
possible path to take, but has far more cost, and potential
issues, than the EEIP plan on record of VEGETATION REMOVAL which
solves the safety issue, with the lowest cost, and elimination
of the public safety issues. We covered this solution before;
HTML https://ecna.createaforum.com/the-stop-the-clearcut-argument/all's-quite-at-the-stcc-forum/msg2482/#msg2482
And the cut-off wall idea was all covered in the extensive SEQR
Investigation and reported already. It was mentioned that this
"Slurry Wall" approach may be useful for locations just like
this one in the Town of Royalton.
HTML https://www.canals.ny.gov/Earthen_Embankment/FGEIS/NYSCC_EEIP_Final_GEIS_BlackText.pdf
NEW YORK STATE CANAL CORPORATION
Earthen Embankment Integrity Program - SEQR Final Generic
Environmental Impact Statement
2.3.3 Install Continuous Cutoff Walls Along Embankment Crests
A continuous seepage barrier could be provided by installing a
continuous cutoff wall along the crest of the embankments to
lower the phreatic surface within the embankment and reduce or
eliminate concerns with seepage and piping failures. Lowering
the phreatic surface also improves the stability of the outboard
slope of the embankments, thereby reducing the risks of
embankment failure.
There are several available cutoff wall options including steel
sheet piling, cement bentonite slurry, and deep soil mixing.
This alternative would require no substrate preparation in the
bed of the canal or feeder and would yield no reduction in the
cross-sectional area of the canal or feeder. The addition of a
continuous seepage barrier would have the benefit of eliminating
the need for some of the vegetation removal, animal burrow
filling, and seepage type repairs that would be required under
the proposed action. The installation of cutoff walls would
result in some temporary impacts to vegetation due to the need
to provide sufficient space/room for the equipment and lay down
areas.
The removal of dead, diseased, or imminently dangerous trees
would still be required to ensure safety of persons and
property.
This alternative would require extensive geotechnical
investigations and analyses to determine the required depth of
cutoff walls, to detail how the cutoff walls would abut existing
structures, and to determine solutions for utilities that cross
under the canal or feeder or that are contained within the
embankment. In some instances, the installation of a cutoff wall
could sever tree roots and adversely affect tree health. The
construction-related temporary impacts of this alternative would
include ground disturbance, construction noise, and off-site
detours of the recreation trail.
Since this alternative would not totally eliminate seepage
through the embankment, it is likely to have minimal adverse
long term environment effects from changing the phreatic surface
outside the cutoff walls. Except for the construction-related
temporary impacts of this alternative, including construction
noise, trimming of overhanging canopy vegetation, and temporary
off-site detours of the recreation trail, there would be
negligible long term adverse environmental impacts.
Based on supplier/installer costs, the approximate total
installed price for a cement-bentonite cutoff wall is between
$2.5M and $6M per mile. The lower end of this range is based on
a 25-foot-deep wall. The upper end of this range is based on a
50-foot-deep wall. The system-wide cost to install continuous
cement-bentonite cutoff wall on the 130 miles of canal and
feeder embankments that have already been identified to date
would range between $325M and $780M.
The estimated cost for implementing the initial embankment
repair/restoration for the EEIP is $2M to $4M per mile of
embankment based on 2019 estimates. Due to the previous long
period of deferred maintenance, many embankments will require
tree clearing on the crest and land side, stump removal,
regrading, surface repairs, filling of animal burrows, repair of
drainage facilities, revegetation and other necessary
mitigations, and repair of erosion protection on the inboard
side of canals and feeders consistent with Chapter 3 of the
DGEIS and the Guidebook. Total EEIP project cost for all
embankments needing repair is between $200-$400M.
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