Author Topic: How to recognize an Embankment Dam  (Read 24 times)

Doug K

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How to recognize an Embankment Dam
« on: June 17, 2018, 11:29:12 am »
It's become difficult for many to wrap their head around the idea a Dam is in their backyard. For those living along the Erie Canal Trailway, mostly along the North side of the Canal where it travels East to West, those "hills" covered with trees and other large vegetation are hiding what is really there.. an Earthen Embankment Dam. Looking from the bottom upward or the ECT down the bank it's rather hard to see UNTIL you remove that large vegetation that's slowly weakening these structures.

This is a time when a picture says it all...
« Last Edit: June 26, 2018, 02:20:09 pm by Doug K »

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Michael Caswell

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Re: How to recognize an Embankment Dam
« Reply #1 on: June 17, 2018, 07:14:58 pm »
Here are some other things to consider.

1. A dam has a spillway, to allow flood water to escape, preventing over-topping which could cause a dam failure.
2. A dam has rip-rap, those rocks on the upstream side to reduce erosion from wave action.
3. A dam is placed across a stream, or river, or source of water, which coupled with the spillway, keeps the water at a fairly constant level.
4. Earthen embankment dams are constructed in similar fashion to the canal embankments. However, NYCC dams were constructed over 100 years ago, without the experience  of modern engineering practices.

Doug K

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Re: How to recognize an Embankment Dam
« Reply #2 on: June 19, 2018, 12:27:43 pm »
Great Points shared on how to recognize an Embankment Dam, Mike, seems many sometimes try to define these Embankment Dams as Levees which is incorrect...here's the 4 main points on how to recognize a Levee. These descriptions are from authorities on Levees, FEMA, USACE & Dr Donald Gray.

1) Earthen Levees are normally constructed parallel to an existing, natural waterway, stream or river. They are placed in a location WIDER than normal confining banks of the waterway and built HIGHER than those banks to protect against overflow. An earthen levee is constructed to prevent flooding of adjacent low-lying areas during periods of high water.

2) Earthen Levee walls are normally dry most of their life, used only as secondary protection from flooding during seasonal related high water events like Spring thaw or when extreme weather events occur with torrential rain that causes those natural waterways to rise.

3) An Earthen levee is subjected mainly to tangential-hydraulic forces (lateral scour) whereas an Embankment Dam is subjected to dynamic hydraulic forces (wave action).

4) Earthen levees have been built mainly to withstand breaching that can occur during over-topping conditions in extreme flooding, through-flow and lateral scour.  The presence of vegetation on a levee helps prevent erosion that can occur during over-topping and lateral scour. By Comparison an Earthen Embankment Dam is designed and built to prevent over-topping and minimize through-flow (seepage).

In summary Mr Donald Gray also has made the following comment regarding Embankment Dams & Earthen Levees: "I donít know of any earth dams where woody vegetation was purposely planted or allowed to grow on a face of the dam.  Such is not the case with earthen levees where vegetation can often be found growing on both the landward and water sides."

Mr. Gray obviously has not been to Upstate NY and visited the Erie Canal in quite awhile

Here's what Wikipedia says about Earthen Levees & Embankment Dams:

https://en.wikipedia.org/wiki/Embankment_dam
https://en.wikipedia.org/wiki/Levee

Don't be misled here folks.. These are Embankment Dams that lead upwards to the Erie Canal & it's Trailway. They are FULL dams from May - November and PARTIALLY Full Dams from November to May... still a threat to those living below them.
« Last Edit: June 19, 2018, 01:21:07 pm by Doug K »