We want to build canoe launches along our local river, the Red Cedar in mid-Michigan. We have a method in mind but want to see if people think it’s suitable.
We’re thinking of using a simple gravel “fan” over a soft loamy muddy riverbank and transition area. How does that sound?
I see pics of canoe launches and they’re usually in places with firm graveley banks already and for rivers that have firm bottoms as well. Usually gently sloped.
Our river is very slow, mostly a few feet deep, and about 30-feet wide. It meanders through low forest, often with farms beyond. Our riverbanks are soft loam. Our riverbottom is quite silty and often soft. When we have rain the river rises and falls a few feet in a day. It’s muddy with lots of vegetation bankside (prickers, nettles).
We have one “built” canoe launch in 25 miles. The very few locals who paddle just tramp a muddy trail down to the bank thru the tall weeds then slip’n’slide on the mud down several feet to the very soft water’s edge then try to step on an accidentally placed stone before they muddy-up their canoe bottom.
We are thinking that we could fabricate simple canoe launches by mowing an 8-foot path thru the weeds and dumping and spreading a layer of white limestone gravel in a fan shape from the upper area, down the bank and out into the water a few feet. The whole launch zone is about 15 feet “deep” from flat land beyond the river thru the weeds, dropping a few feet down the bank and into the water.
We would use pinned beams as steps and erosion control where needed. If there’s a bit more pathway from mowed grass park area to transition zone we would woodchip that.
We can pick sites with current flowing by so that the launches won’t silt-in. Sometimes our river bottom is even a bit firm with some sand and gravel.
We’re wondering how our plan might hold up to water levels that rise and fall a few feet frequently. And how well dumped and spread gravel holds up with a soft mud base situation.
Does anyone know of successful cases of launches like I describe? Anyone have any pics they can point me to? I’d like to show an example of what I mean to the park manager.
THANKS!
It won’t be practical.
This doesn't sound like a good idea to me. Crushed rock with fines is out of the question because in a loose-dumped condition, it will be nearly as soft as mud when saturated. "Clear stone" (crushed rock without fines) would be more practical but will cost more, and when you refer to it as "white limestone", that makes me think of something from a landscaping supplier, driving the cost up even more.
Neither material will be stable on a steep bank, and neither will be firm and stable when placed in a fairly thin layer on a soft mud substrate that's sometimes submerged. Placed on a muddy river bottom, it won't be long before you have a mud-gravel mix that's a little firmer to walk on than mud, but not any cleaner. You could increase the particle size of the crushed rock, going to something in the range of three- to six-inch size, but that stuff isn't very boat-friendly (it'll scrape the heck out of boats of people that like to drag them), and the material will still eventually disappear into the mud substrate unless placed in a pretty thick layer (probably about two feet).
Here's another consideration. A thin layer won't hold up for long on the slope or riverbed, so let's just say you put it down one foot thick (which in my opinion is likely still too thin to be useful for more than one season). A ramp that's only 10 feet long, 5 feet wide and one foot thick will take 1.9 cubic yards of material, and in a loose condition that's roughly 6,000 pounds of material. You won't be moving this stuff around with hand tools.
Finally, I launch from river banks like that now and then, and I generally make use of tree roots. Not everyone scampers around on tree-root footholds like I do, but with that idea in mind, if you want to make a specific muddy slope easily negotiable while keeping your boots clean, I'd suggest a set of wooden steps laid on the slope, anchored at the top. Anchoring it with a couple lengths of rope would allow it to float free and sideways against the bank during floods, so it might stand a chance of not being wrecked right away. Even a ladder laid on the slope would work fine for some people (like myself), so making the "ladder" wider with broader steps seems like a viable option.
By the way, the cost of lumber for a set of steps should be less than the cost of a truckload of crushed rock.
High maintenance…
Don't want to rain on your parade, but what you're talking about is going to be high maintenance/high cost over the long haul.
When the river rises & recedes(especially from floodstage), it's going to take a lot of your gravel into the river, and downstream. Also, downhill runoff(erosion) from heavy rain will take some more.
Wood chips will disappear even faster.
Who will pay for replacement of material, and cost of maintenance?
BOB
some help:
What you're describing is filling or excavation of a wetland or waterbody, and when you do it without a permit, it's usually a crime.
Here's a National Park Service document that discusses launch construction options, might be a good place to start:
http://www.nps.gov/ncrc/programs/rtca/helpfultools/launchguide.pdf
If you're a private landowner then technically you should pull a permit from MDEQ, unless it's a seasonally removed launch. If you are a municipality you might get to complete an abbreviated permit.
In Missouri,
the Conservation Department accesses usually have concrete ramps, even if the stream is too small to have a lot of motorboat use. They tend to jut out into the channel, with some rip rap along the sides where the concrete gets close to the water. That way, current in high water events keeps them from silting in. If dug into the bank too deeply, they WILL silt in and be unusable after the water goes down after a flood until somebody comes in and cleans out the silt.
The state park people (MODNR) often prefer corrugated concrete ramps, horizontal strips of concrete about six inches thick and four inches or so apart, for walk-down accesses. Again, if dug into the bank too far, they’ll silt in.
More maintenance, but perhaps practical in your case, would be a treated wood ramp with horizontal wooden “cleats” attached, and anchored to the bank somehow.
I agree with the others, your gravel fan will not work for long.
Will gravel work on firm banks/bottoms?
Thanks for the feedback!
Where it’s soft it seems like treated steps might work.
Where the bank and nearby bottom are firmer, with some gravel already present, maybe more gravel will be helpful?