Questions about Causeways
I have a few questions reguarding building a causeway in very wet and muddy area that our club maintains. First it is a small municipal park at just under 300 acres. These are very easy trails but our club is very young and have work it out with the park board to carry out most of the trail up keep. There are many what I would refer to as marshy areas that have no drainage at all. These areas seldom get a chance to dry as we live in Eastern Ohio and receive plenty of rain.
The park is concerned about how any trails would look and how it would blend in with nature. I feel that a causeway would look more natural in the long run. I also feel that a causeway would be easier and cheaper to maintain in the future.
In these areas of concern the current trail consit of railroad ties or 6x6's placed perpendicular roughly 5' apart and 2x10's place parallel. Not only is this not the best idea on beginner trails but it is very springy and looks awful in my opinon. I would like to install a causway through these areas about 4' wide and I would like to see it stand 6"-8" out of the water and muck to counter act for high water spells. This would make the total depth of the causeway around 12"-18" as I can reach pretty solid ground about 10"-12" down.
So my questions are, Have any of you constructed a causeway, How succesfull was the causeway, and should I use geotextiles for stability, and the cost per foot on this type of project?
Oh yeh does anyone have any photos of causeways they have built? Thanks everyone for reading my lenghty question, and for any answers you can provide
Is it possible to reroute around the marshy areas to higher ground? This would be the cheapest and most "natural" looking option. Not to mention the least labor intensive. I would strongly suggest not building a causeway unless it is absolutely unavoidable.
Check out some of the other methods of crossing wet areas from the USFS's Trail Construction and Maintenance Notebook: Trail Construction and Maintenance Notebook - 00232839 - Forest Service Publications - Publications - Recreational Trails - Environment - FHWA
Causeways require a lot of material, mainly crushed rock. Given your requirements for depth/length, you are going to need 6 ft^3 of filler rock (~700 lbs) per linear foot of causeway. The price of a cubic yard of crushed rock is usually $25-$45 plus transport costs which can be +$100 per truck load (5-15 cu. yd. per truck load).
Rock costs will be somewhere between:
MIN: $6-$10 per foot of causeway (no transport fees).
MAX: $10-$15 per foot of causeway (with $100 transport fee for 5 cu.yd. truck).
Your containment materials will be critical in making the feature low maintenance. What are you planning on using? If it needs to sit in water/wet soil year round large rocks or other non-rotting materials would be the best solution. If the containing structure is built properly you shouldn't need to use geogrid for stabilization but it would offer some insurance against failure if you have the funds for it.
Depending on how long your causeway needs to be and how far it is from your material delivery site it could take a significant investment of labor to get the materials to the site. If it is a long distance and/or uphill you will want to get a powered wheelbarrow. ($50-$60 a day to rent)
You may also need to investigate how much the causeway will sink and build higher to take settling into account. There will be a significant amount of weight added on top of the soil.
Check out this one we built. Wood was salvage from an old dock and storm damage. Also cut down some nearby. All deck boards milled with chainsaw.
Grand Ridge Boardwalk - YouTube
There's a big difference between ripping and skidding. Those who skid don't know how to ride.
We put in some causeway (we refer to it as "turnpike") last fall.
Originally Posted by redd4573
We were fortunate to have road access immediately adjacent to the wet area. The park management uses several dump truck loads of gravel per year. The management graciously donated ~7 front-end loader buckets of gravel for our use, which translated to ~80 yards of trail dug approximately 8" deep (piled up to 10-12") and about 30" wide.
We're also fairly lucky in that the mud is a relatively shallow layer of black silt leaf compost over hard clay. That, and the free (to us) gravel made the project feasible. The concern that I kept getting was that the gravel surface would be not natural looking or loose and unsafe to ride on.
These turned out to be true, but only in a very limited sense. No one is complaining how it looks as completed. Wanna-be racers can't barrel through the curves at as high a speed as previously, but given the other issues that have been solved, I can't give this one too much weight. ( I witnessed a rider dump his bike by skidding into the intersection at the end of the turnpike, but because he brought it on himself by riding into a limited sight-line intersection at full speed, I didn't feel sorry for him at all.)
Even with the good outcome we've achieved, I agree with the aero901 that this is extremely labor intensive work. A re-route wasn't feasible in this area due to lack of space and options.
We have built several turnpikes over flat, wintertime swampy spots using gravel. We'll put down 2"-3" gravel as the base and then topped with 5/8" minus. Figure how much gravel you'll need and then add about 10% for settling and compaction. A power wheelbarrow is a life saver for moving the stuff. We have had good luck getting high school kids who need community service hours to come out and help. Gravel moves fast when you have 40 kids with wheelbarrows.
Here is an example before/after (turnpike was built in May when things were drying out):
Here is the same turnpike eight months later. Blends in pretty nicely.
Thanks guys I really appreciate your responses. First to answer aero901, No a reroute is not possible. To woodway thank you for the photos they are just what I was thinking about and I can use them to show the park board what it will look like because I knew it would look fine but they did not understand as they did not want a big ugly gravel walkway. I plan on using #2-3 limestone with #57 used to fill voids in the larger limestone and then cap the whole thing with 304 which is a #57 and limestone sand mixed in together and it will be compacted down to form a pretty hard stable surface. Then just wait for mother nature to put her finishing touches on it.
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