Northerly Island path collapse
I rode to Northerly Island last night for the first time since last year and the path on the lake side has completely collapsed in a couple of spots.
Does anyone know of the Parks department's plans about this? This would be a major reconstruction and would probably require an effective breakwater off the shore to prevent it from being washed out every few months.
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Replies to This Discussion
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Permalink Reply by Carter O'Brien on
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"because of the massive lakefront barriers, which, oops, never happened"
ahhh - the ones Jeanne Gang and her team envisioned as protecting a snorkeling and kayak launch area, right?
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Permalink Reply by ketoguychicago on
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That's right Carter. Those features were pretty key to the whole design she envisioned.
A key omission like this happened elsewhere when someone replicated an ancient boat design, and when it was built, there was a feature that didn't seem necessary when assessing at the boat on land. So it was removed from the final build, and too late on the water after a few days it was discovered that the feature was key to supporting the boat materials once they were in the water for a while and became waterlogged.
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Permalink Reply by Tooscrapps on
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I'm having trouble seeing how a culvert would prevent the constant pounding of waves. This damage isn't from water trying to find a way into the lagoon, but rather just the nature of the lake and its swells.
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The waves come up and over like you're mentioning, but the problem is the erosion under the sidewalk when the water tries to find lower ground as it flows to the lagoon. The culverts can handle/channel this water so that it doesn't erode the ground under the sidewalk. I've watched this on a windy/wavy day when Michigan kicks up her heels with an easterly, and it washes the dirt out as it flows west and under the walk-way. Initially it was held back by the dirt, or flowed right over the top of the sidewalk, but eventually the dirt just wears away, and then it becomes the water's regular path, washing it out even further. Really a bummer.
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Oh I get what you're saying. So you have lake/wall/basin/berm with culvert.
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Yep that's right, and the path runs along the top of that berm. Some engineers skip the basin, and would just put a wall on the lake side of the berm to strengthen it. Which version makes more sense depends a little on the scale and typography. I just hope we get something otherwise the whole thing is such a loss for everyone.
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Permalink Reply by Elwood Gruschow on
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Yes, the problem is the flow of water through sand under the sidewalk. The accent is on flow. The same lake front barrier was on Miegs field and there was never a wash out problem. I am referring to the pilings and crib shoring from that era, not the new view-blocking-boulders. The problems happened when they dug a lagoon so water washing on the shore flowed through the sand under the side walk and washed it out. A wall of sand with water flowing out of it will flow out close to horizontal. They did’t read Matthew 7:24-27.
A system with impervious membrane or catch basins above the sand collecting the water then directing it under the path through culverts could work.
Putting the entire east path on pilings above water level could also work. Historically there was a train line that ran along the shore line on pilings, too bad there wasn’t an early rails to trails movement then.
Filling the lagoon back in would also work.
The current plan of construction starting this fall is hard to visualize just from the Tribune article. I read it as the current west path will terminate in a turn around just behind the view-blocking-boulders. The remains of the east path will be removed. A maintenance route be in place where the east path was, but it will not be a recreational path. That is my reading of it. I hope the “maintenance route” is a gravel road and not closed off by Chainlink (fence), barb wire and Jersey barriers but we will see. I hope we also see the complete removal of the Hamilton exhibit including all foundations and earth works.
I visit NI often. If you see a person sitting in a bikeable folding chair and reading at the current southwest path end say hello. You might also spot and my bicycle on the south end of the island when the island is closed because of concerts. I was exiting the south end on my bike during the Manilow concert when stopped by a security guard. He said the bike path was closed. I said will you let me through to go home or do I stay until the end of the concert.
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They are starting on Northerly Island plan 2019. I think all of the south part of the island is closed. (August 15, 2019) The sidewalk slabs on the east leg are crushed and the west loop entrance is fenced off. I rode into the island about 4:30pm yesterday did a little reading and flower looking. When I started home after 5:30pm a fence had been installed at the exit by the giant party tent. The closing is to protect us cyclists from crossing the new east-west gravel path. The new road (temporary ?) is there to allow trucks and equipment access to the eroded east loop. It looks like they may leave a gravel road where the east loop was, but use large aggregate gravel. I have a nice mountain bike I do not ride much, maybe riding on big chunk gravel will be the new fall activity.
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Anybody see anything here lately? Elsewhere the water's high, and with the east winds of late this may be tricky still.
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When I was there last week the contractor locks access to the entire pretty southern section during workday. This is prevent cyclists and joggers from hurling themselves under the slow moving dump trucks that go by maybe 15 minute intervals. After 4:30 they change the gate near the giant party tent to block late dump trucks and allow southern access. I think it is open all weekend to joggers and cyclists.
The lake level has not affected much change. The lake is currently just under 582 feet. It was over 582.5 back in 1987. There have been no changes in the pilings and shorrings since construction of Meigs Field (pre 1987). It was stable then. When they dug the big lagoon in last reincarnation it allowed water and more importantly sand fill to flow from under sidewalk into the lagoon.
The contractor is supposed to leave a "maintenance access" along the east lakefront. It would be nice if it open to joggers and cyclists. It will likely be gravel which I decided is not bad, since it hinders Segways, quad cycles ,and electric pedicabs.
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Wow, great report, thank you Elwood.
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