Links to Embankment Dam Reference Material > Links to Embankment Dam Reference Material

Thatching! It's over 5000 years old!


Michael Caswell:
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!

Doug K:

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'

Here's what the Brockport East Dam looks like after this step of the EERP Process

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.

Michael Caswell:
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.

Doug K:
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.

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.

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:


[0] Message Index


Go to full version