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DIR Return to: Just the Dam Facts! - Embankment Reference Material
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#Post#: 222--------------------------------------------------
Thatching! It's over 5000 years old!
DIR By: Michael Caswell
Date: December 23, 2018, 4:08 am
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Man has used thatching to protect him from the elements for a
very long time. It's a well proven method of shedding water from
a structure, so when you apply that thinking to The Great
Embankment, it makes sense.
Looking at the problems with embankments, it's easy to realise
that too much moisture can be devastating for these slopes if
they become too saturated.
A Phreatic Line where moisture from the canal itself soaks
through the fill of the embankment wall is quite acceptable as
long as the liquid can escape below the toe of the slope.
However, if the drier material above the Phreatic line becomes
saturated too, then there is an increased risk of a slide.
Grass growing on an embankment is like a thatch, it sheds the
rainwater down the slope, keeping the bank dry. It's the obvious
choice for a low maintenance protective covering. A grass
covering also makes it easy to spot nefarious woodchucks at
work!
HTML https://upload.wikimedia.org/wikipedia/commons/8/81/Pub.williams.arp.750pix.jpg
#Post#: 248--------------------------------------------------
Re: Thatching! It's over 5000 years old! Still being used on
the Erie Canal
DIR By: Doug K
Date: January 3, 2019, 7:05 pm
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Mike,
I waited to post this reply...knew the real "thatching" was
coming along soon. Those straw thatch mats being placed atop the
repaired root pulls are now all neatly joined together with
still another Process Step in the Earthen Embankment Remediation
Project. Today a straw "cannon" was slowly pulled along the Erie
Canal Trail with 3 operators aboard and one driver maintaining a
constant slow speed.
One person pulled straw bales and fed the loading chute to the
Thatch Cannon. Another person cut & removed the bales cords and
pushed the bale into the chamber where it was shredded and
blasted out. The person manning the cannon itself had to "play
the wind" as each gust did play a role in where the straw thatch
landed.
I'm sure someone in the STCC will post about how it was messy
and loud... but from my vantage point, ringside, it was fast and
efficient. They have about a 2 mile long by 22' average height
section of Earthen Dam in Zone 37 and this looks like the last
step before more topsoil, grading and grass planting come next
Spring.
Here's some pictures... and a nice Before & After at the end.
Thatch Cannon - Shooting Straw Thatch about 30-40'
[attachimg=1]
Here's what the Brockport East Dam looks like after this step of
the EERP Process
[attachimg=2]
And voila.. the Embankment is now ready for the final steps of
add topsoil & contouring then the hydroseed..and most likely we
will see the Straw-Thatch Cannon again.
[attachimg=3]
#Post#: 251--------------------------------------------------
Re: Thatching! It's over 5000 years old!
DIR By: Michael Caswell
Date: January 3, 2019, 8:50 pm
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A great operation. Not exactly what I was portraying in my
thatch theory, because I think this operation is more of a
mulch. It's temporary, but never the less, it's function is
similar. It sheds the rainwater, stopping the soil from being
eroded and washed away.
In the Spring, grass seeds will be spread on this mulch and
grass will grow. When this happens, the grass will provide a
permanent thatch.
#Post#: 252--------------------------------------------------
Re: Thatching! It's over 5000 years old!
DIR By: Doug K
Date: January 4, 2019, 9:34 am
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Actually this layer of straw mat & blown thatch combination is
the middle of the Embankment repair sandwich. From what we've
heard there is more topsoil to come that will cover & recontour
the outboard slopes, of many dam sections, to have the final
outboard dam slope something less steep and easier to maintain.
In the end the Embankment will look like this if you did a
Before & After cross-section.
[attachimg=1]
I've heard that some embankment sections will get as much as 24"
more of topsoil, which made me think about how much dirt might
be needed... big numbers usually turn more heads.
For a typical property width of 100' and the EERP Phase 2
western zone embankment sizes... seems 30' width outboard slope
seems close to average. That would mean about 222 yards of
topsoil to go 24" deep. What get's amazing is when you take that
out to the EERP Phase 2 current work, about 32 miles of
Embankment Dams between Lockport & Spencerport. Here's a look at
the Topsoil Calculator for that equation.
Wow, over 10 million cubic feet of topsoil will be needed,
that's about 375,000 cubic yards. Typically, dump trucks haul
10-14 yards per load, so this is about 31,250 dump truck loads
for the 32 miles of EERP Phase 2 work underway. And there is
still another 10 or so miles to do in Brighton, Pittsford, and
Fairport.. so another 10-12 thousand loads there. That may be
light as the Embankment Dams east of Rochester are much taller
and have longer Outboard Slopes to reshape.
[attachimg=2]
Can't help but notice that these EERP Constructions Companies
are also trying to source materials locally when possible &
practical. Hopefully this means our local topsoil providers will
all be bust come Springtime.
We are not quite mid-point of EERP Phase 2 in Brockport, the
safer Embankments are taking shape, and hopefully we start
discussions soon with the Arborist who will be working with
homeowners who need evergreen barriers constructed. Many
homeowners are still hoping to reduce the Erie Canal Trail
visibility into our personal lives, for some of us there is zero
separation now between Erie Canal National Heritage Corridor
patrons and our dinner tables.
Quite a Transformation so far:
[attachimg=3]
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