Tell the politicians and the NYPA that you support the work being planned to remove invasive vegetation from the Erie Canal Embankments. These dams have been designated Class C High Hazard, likely to cause loss or life an property if they were to breach, and the only solution is to remove the invasive vegetation and replace it with grass, as per FEMA, NYDEC, ARMY CORPS OF ENGINEERS, & ASSOCIATION OF STATE DAM SAFETY ENGINEERS policy of ‘No Trees On A Dam’
Author: Mike Caswell
Phreatic Line and Horizontal Drain In Earth fill Dams
Earth dams are generally built of locally available materials in their natural state with a minimum of processing. Homogeneous earth dams are built whenever only one type of material is economically available.
The material must be sufficiently impervious to provide an adequate water barrier and slopes must be relatively flat to make it safe against piping and sloughing.
The general design procedure is to make a first estimate on the basis of experience with similar dams and then to modify the estimate as required after conducting a stability analysis except where there is a surplus of material.
The United States Department of the Interior Bureau of Reclamation (USBR) and other agencies suggested limits for the upstream and the downstream slopes for different types of materials and dams.
The upstream slopes of most of the earth dams in actual practice usually vary from 2.0 (horizontal):1 (vertical) to 4:1 and the downstream slopes are generally between 2:1 and 3:1(USBR 2003). Free board depends on the height and action of waves. USBR (2003) recommends normal free-board about 1.5 to 3 m depending on the fetch. The width of the dam crest is determined by considering the nature of embankment materials, height and importance of structure, possible roadways requirements, and practicability of construction. A majority of dams have the crest widths varying between 5 and 12 m.
About 30% of dams had failed due to the seepage failure, viz piping and sloughing. Recent comprehensive reviews by Foster et al. (2000a,b) and Fell et al. (2003) show that internal erosion and piping are the main causes of failure and accidents affecting embankment dams; and the proportion of their failures by piping increased from 43% before 1950 to 54% after 1950. The sloughing of the
downstream face of a homogeneous earth dam occurs under the steady-state seepage condition due to the softening and weakening of the soil mass when the top flow line or phreatic line intersects it. Regardless of flatness of the downstream slope and impermeability of soil, the phreatic line intersects the downstream face to a height of roughly one-third the depth of water . It is usual practice to use a modified homogeneous section in which an internal drainage system in the form of a horizontal blanket drain or a rock toe or a combination of the two is provided. The drainage system keeps the phreatic line well within the body of the dam. Horizontal filtered drainage blankets are widely used for dams of moderate height.USBR constructed the 50 m high Vega dam, which is one of the highest with a homogenous section and a horizontal downstream drain.
The minimum length of the horizontal blanket drain required to keep the phreatic line within the body of the dam by a specified depth and also equations for maximum downstream slope cover and minimum and maximum effective lengths of the downstream filtered drainage system.
The position of the phreatic line influences the stability of the earth dam because of potential piping due to excessive exit gradient and sloughing due to the softening and weakening of the soil mass as if it touches the downstream slope or intersects it. When the dam embankment is homogeneous or when the downstream zone is of questionable permeability, a horizontal drainage blanket is provided to keep the phreatic line well within the dam body, to allow adequate embankment and foundation drainage, and to eliminate piping from the foundation and the embankment.
As the dams are made of fine-grained soil, saturation may occur due to the capillary rise above the phreatic surface so it is necessary to account for capillary rise while calculating the minimum length of the downstream filtered drainage. Though the suction head in the soil matrix above the phreatic surface within the dam body due to capillary rise generally improves the stability of the downstream slope, once the capillary fringe intersects the downstream slope the pressure changes from negative (suction) to atmospheric and the downstream face may become a seepage face leading to its failure. Hence the phreatic line should not intersect the downstream slope and it should be a distance greater than capillary rise below the sloping face so that the chances of the sloughing or piping may be nullified.
Great Movies from the NYPA and ASDSO
Here’s the latest on the safety measures for Perinton
With Mike Caswell! Erie Canal Neighbors Association
This second video will give you a good idea of what is coming to the Perinton dams later this year.
Stage one will be the removal of all vegetation from the outboard slopes of the dams.
Stage two will be to restore privacy and other issues to residents living adjacent to these dams.
With Doug Kucmerowski Erie Canal Neighbors Association
This movie demonstrates why it so important to do this work. All folks living adjacent to these dams are in a Flood Hazard Zone.
Here’s what the Perinton Dam looks like at present. Mike Caswell’s amateur video showing his perspective of the dam from 31f to The Oxbow.
For more documentation please visit http://www.eriecanalfacts.wordpress.com
and the Erie Canal Neighbors Association forum
Get The Latest Information About The Erie Canal Embankment Integrity Program
See The Erie Canal Neighbors Association for discussion and up to the minute reports about the progression of this important safety program.
The Great Embankment
Here is a brief history of the construction of The Great Embankment.
A video on the construction of The Great Embankment
Erie Canal National Heritage Corridor
List of posts
- Erie Canalway Neighbors Association Adopts Historic Oxbow Trail
- Culvert Washed Out in Recent Storm
- What are you putting in the canal?
- Huge Tree Blowdown in Fairport
- CANAL CREWS SET TO BEGIN NEXT PHASE OF EMBANKMENT WORK IN WESTERN NY
- The NYPA and the Canal explained.
- Testimony in question – Vegetation on Dams.
- Rizzo Report on State of Canal Embankments
- A pending disaster
- Have You Heard the Hammering?
- At Last! We have 20 Years Worth of Inspection Reports!
- EMERGENCY EMBANKMENT DAM REPAIR!
- NYPA Save The Oxbow Embankment Dam From Slope Failure
- An Expert Opinion!
- Weeds – or shrubs and flowering bushes?
- Brockport Tree Cutting Machine
- Anatomy of an Erie Canal Embankment Leak.
- How and Where to Plant Cottonwood Trees
- Where is the Flood Zone?
- Environmental Review delays work!
- Clear Cut = Full Steam Ahead
- What are they hiding?
- It’s a Rotten Wood
- Marsh Road Bushnells Basin Bridge In Serious Condition.
- The Dispute about Vegetation Removal and SEQR
- FERC. Internal Erosion & Piping on Dams
- Rizzo Corp maps of Vegetation Removal Areas on The Canal
- It’s Official – Canal Embankment at Fairport classified VERY POOR – HIGH HAZARD!
- Minutes of Canal Corp Meeting Brockport
- More documents come to light
- Then – and now!
- A Brockport Afternoon
- Keeping The Canal Safe For Generations To Come
- Canal Embankment Cleanup
- Who else thinks trees should not be allowed on Earthen Embankment Dams?
- Lessons Learned from Katrina
- GUIDELINES FOR LANDSCAPE PLANTING AND VEGETATION MANAGEMENT AT LEVEES, FLOODWALLS, EMBANKMENT DAMS, AND APPURTENANT STRUCTURES
- Bushnells Basin & Fairport – High Potential Hazard Embankment Dams?
- Problems with Trees and Brush Near Dams (NY DEC)
- More about dams.
- Earthen Embankment Dam Inspection
- Piping -another problem with embankment dams.
- Hazard Creep Dams designed to lower risk criteria.
- A Comparison with The Netherlands
- Is it a dam, embankment, levee, ditch or dike?
- NYS Vegetation Management
- The Phreatic Line! Huh?
- Power from The Canal
- This is a MUST READ!!
- Dam Design
- The Erie Canal Vegetation & Remediation Project
Erie Canalway Neighbors Association Adopts Historic Oxbow Trail
Culvert Washed Out in Recent Storm
Last night, we had a strong thunderstorm, and the culvert flowing through the Oxbow feeding the canal was washed out.
The ‘bridge’ over the culvert is the old towpath for the original canal. The water flows from Minerva Deland school playing fields into The Oxbow Lake.
This structure been recently refurbished using plastic pipes, as the old ones were rusted out.
Seeing as how this is a new repair, how did this happen after only ONE heavy storm?
It’s the overall design that is at fault. These small pipes simply dam up the exit with debris that naturally falls into flooding streams.
The water can’t escape, and so it flows over the top of the trail.
The next problem is that no rip-rap or concrete barrier was placed on the upstream side of the trail, so scouring of the gravel took place.
Small particle size gravel was used as fill over the pipes. This tactic was used before and rocks about 6″ – 8″ were used, and these washed out.
After every rain storm, The Town of Perinton staff visit and remove the debris. Unfortunately, they don’t take it away, and leave on the side of the culvert, where it washes back and clogs the pipes again.
Perhaps the answer is to remove these pipes and simply replace them with a wooden footbridge? There would be much less maintenance and it would prevent motorized vehicles from accessing the trail?
This is a classic case of a culvert becoming clogged with debris and subsequently over-topping. It just took one thunderstorm. Imagine if this had been on a canal embankment dam culvert or spillway. The dam overflows and the soil is easily washed out – scouring. A couple of hours of this and an embankment dam would fail.
Updating this post July 24th 2018
Last night’s heavy rainstorm caused more damage to our culvert. Much soil was eroded from one side where the culvert is lined with concrete. Scouring has occurred behind the wall, which will eventually collapse.
Another hole has appeared more centrally and a great deal of gravel has been washed away.
A lot of bedrock is now exposed at the upstream side of the culvert tubes, and of course, they are partially blocked by debris.
I would guess that another rainstorm will wash out the area completely. At least it will make pipe removal a simple process!
UPDATE 8 14 2018
A huge rainstorm washed out the rip-rap, pipes and gravel completely today.
UPDATE 8 15 2018
All traces of bridge – gone!
Here’s the old pipes.
What are you putting in the canal?
There are many things that shouldn’t go into the canal, but most people have no idea why.
Canal water is a vital source of irrigation to many farmers and homeowners growing their own produce.
A trip along the canal in a boat will reveal, if you are observant, many small pumps installed along the shoreline. These are used to irrigate lawns, vegetable gardens and farms growing the produce you probably buy in places like Wegmans or Tops. These retailers love to use local producers as it supports the economy and everyone benefits.
So, imagine someone spraying a toxic chemical on vegetation along the shoreline with scant regard to the over-spray contaminating the water. Fertilizer excess on lawns and fields, causing it to run off into the canal causes nitrogen excesses resulting in algae blooms and more. Throwing the odd bit of dog poo in, allowing Canadian Geese to contaminate your lawn, feeding them and ducks etc. etc. It all adds up to a nasty soup in the canals, which has caused a major outbreak of E coli in romaine lettuce sold across the nation.
We need to be more careful and realise that our canal water needs to be kept cleaner!
Huge Tree Blowdown in Fairport
Thanks to the new forum for the Erie Canal Neighbor’s Association, a huge tree blowdown has been uncovered.
Just a few feet south of the electricity pylons at the Oxbow, almost a dozen large trees have been ripped out of the canal embankment dam. Many are leaning on upright trees, so it’s likely more will fall in the near future.
Here’s a video of the situation.