river access design

[dvd]

I am interested in designing a small access (~ 8 ft. wide) to the water at an outside bend on a small shallow river. The outside bend has created an approximately six foot tall bank in a rocky soil. I would like to know more about the subject. Any recommendations on literature, or general discussion, addressing the topic of building river access points would be appreciated.

 

[Drumchaser]

Generally speaking, access points, boating ramp etc.s are constructed at protected areas, that is to say locations where the flow will not erode the bank cuts during rainfall events/cresting of water. (when the river gets up)

Sometimes small shallow rivers become large nasty rivers.

If the soil(s) are rocky this may not be a big issue. You can pave areas with concrete to inhibit such things.

Bulkhead(s) tend to help discourage erosion. Have seen folks stack bags of ready mix conc. to form crude bulkheads (that work), have also seen large rocks placed along such areas, as well as other more expensive walls/piling.

The larger issue would be the potential for required permitting with the regulatory agency that has jurisdiction.

Also, you may want to elaborate on "access"....boat?...swim area?....

 

[dvd]

Thanks for the response. Access is intended for launching canoe/kayaks, no boats on trailers. I have attached a conceptual sketch of what I think this should look like. I would like to apply some engineering thought, however.

At this time, I would like to establish what design steps would be necessary to construct a reasonably stable opening in the bank. If it seems like it may be possible, and economically feasible, then I will investigate permitting.

 

[BigInch]

That's not a good place. That is theoretically the fastest sweep, the place of the fastest velocity of current on your whole diagram. Remember ice skating on the end of the whip? Get off the outside bend. The river is eroding in that direction. Go back over to the left and up, before the river starts the bend.

What would you be doing, if you knew that you could not fail?

 

[cvg]

recommend you put the boat launch on an inside bend. erosion will be a continual maintenance issue on the outside cut bank. if you are set on building at this location, then you should plan on a significant amount of excavation and erosion protection.

 

[dvd]

Property lines, access and topography cause the outside bend to be the preferred location for me.

Attached is an aerial view of reality.

I would like to engineer a solution, but mainly just understand the design process required to accomplish this.

 

[BigInch]

cvg, if he could reach the other side of the river now, he wouldn't need a canoe landing.

If flow is right to left, it doesn't look too bad. If flow is left to right, you're screwed.

Mother nature doesn't give a rat's A about property lines.

What would you be doing, if you knew that you could not fail?

 

[cvg]

i wasnt suggesting the other side of the river, just moving up or down stream a ways.

by the way, you will need a 404 permit. suggest you check on that before you start.

 

[dvd]

Thanks for the interest folks. The flow is right-to-left as pictured. (I put flow direction on conveyor drawings everyday, I should know to extend that courtesy.) See latest attachment.

I have looked at USACE 404 permit info, thanks cvg. Sounds like this project falls under the General Permit guidelines; doesn't sound too scary. I would take the 404 permit matter up with the state authorities prior to commencing any work.

 

[cvg]

you will need to take that up with the corps of engineers, not the state.

 

[Drumchaser]

Good lock with the Corps. You may need to take a foreign language class so you can communicate effectively.

 

[dhengr]

dvd:
You last photo doesn’t look as bad as your first sketch did, in terms of making a canoe access on the river. That’s assuming that all the zoning and permitting will allow this. And, I leave that to others with more experience in dealing with Corp. of Engrs. and your local DNR, etc. They can seem pretty unreasonable at times, and yet we probably don’t want an access, however well thought out, ever 200' on any river or lake. In Minn. and Wisc. we have pretty restrictive building set-backs, bank clearing widths and vegetation disturbance set-backs, and generally no construction beyond the OHWM, except for a pier. This is all to improve the water quality and public view from the public waterway. But, much damage has already been done, and that is really tough to police and reverse.. And, in part it is the old... my landing is o.k., but your’s is one too many, mind set.

You want to avoid the outside bank of any bend in the river because of scour, bank undercutting, etc. This also leads to deep water holes near the bank which are not conducive to canoe/kayka launching. Preferably, you want shallow, gradual slope, at the bank so you can wade out and load and get into the canoe. Almost any cut in that 8' high bank will lead to erosion with out very careful civil design. For this reason, you might be better with a set of elevated steps down to a small landing on or over the water (a pier). This can be installed with some minimal posthole digging, and very little disturbance of the bank and bank vegetation. You even want to be careful with a construction pathway up/down the bank because it becomes a place for erosion to start. The landing and the last couple of steps should be easily removable in the fall or during periods of high water or you’ll be continuously replacing them.

Try your local DNR and Ag. Dept. for stream and stream bank improvement pamphlets, and access design ideas. Small wing walls as you showed in your sketch can be helpful in some cases, if they are allowed to be built.

Good luck.

 

[dvd]

Thank you all for your input.

dhengr, although I can enter a kayak while standing in the water, my only real goal in life is never to get my feet wet when launching a boat.

 

[beej67]

You can never tell what's going to be a general permit and what's going to be an individual permit with the Corps.

I'm on a project right now where a storm drain culvert collapsed due to a small creek oxbowing out too near a subdivision culdesac. I want to realign about 80 feet of the creek away from the culdesac, to have enough slope to get the new replacement culvert in.

If I left the creek were it is and built a 20 foot concrete retaining wall right into the bank, to discharge the culvert there, that would be a general permit.

If I tore the entire culdesac out and benched the slope back into the road, that would be a general permit.

If I built a bottomless arch through about 50 feet of bend, at a cost of a quarter million dollars, then that would be a general permit.

If I rebuilt the thing exactly like it was, so it'd fail again in two years, that'd be a general permit.

If I realigned the creek out of the way so I could build a house over the previous creek location, that'd be a general permit.

If I wait for the culdesac to collapse into the creek I can fix it however I want and ask forgiveness later.

But since this is a maintenance activity and not new residential construction, and the maintenance GP doesn't allow you to realign creeks, I have to get an individual permit. I have to send a farging archaeologist out to dig test pits and make sure there aren't any indian burial grounds in the 80 foot realignment area, and I have to draw up four sets of "alternatives analysis" plans.

*

I don't mean to disparage your idea, DVD, but the reason I'm not disparaging it isn't because it'll work. I just want you to go through with it and post your trials and tribulations here for we civils to chuckle at. Good luck!



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