I need an educated opinion on a lake erosion problem

[lkb]

At my lake the boathouse/dock  is about 100 feet before you get to the pregates. The banks were built on a 10:1 slope which runs 20 out underwater before dropping of on a 3:1 slope. When I built the lake 6 seasons ago, I had a nice sand beach on either side of the dock. Now the sand is gone and the bank has steepened to something more like a 6:1 slope. The slopes are still good everywhere else.

I'm thinking of stacking bags of quickcrete to build an underwater retaining wall. The top of it would be about 1' underwater. It would run parallel to the shoreline about 15' out from the water's edge. Then I would dump fresh sand to make a new beach. My hope is that this wall would hold the sand in place this time and it would also break some of the boat wake energy before it hits the sand making it even more likely to stay in place. 

The soil here is Alabama red clay. Everytime somebody walks out of the water the mud gets tracks and stains everywhere. I'm desperate to cover up the mud and to get that portion of the bank back to a 10:1.Does anybody think this will actually work? Any suggestions? Thanks

[eleeski]

Quickrete bags worked as a shoreline retaining wall at Stan's lake. Just place them and they get wet and hard. After a while the paper peels off. It actually looks OK.

As for keeping a sandy beach in clay, good luck. After trying lots of sand, sand over astroturf, and finally the biggest mistake - sand over concrete, I give up. Nothing stays for long. The sand migrates to the most inconvenient spot and I now have a slab of concrete to eat props. All that is left are blobs of clay the don't wash away with the sand and a rough slippery "beach". Build a Trex dock instead. My mud is extra gooey nearly pure bentonite so I might be a worst case - at least my lake doesn't leak much.

Eric

[Director Darwin]

Your problem is the 10:1 slope.  I cut my ends 15:1 to accomodate a beach.  The other issue is the type of sand you use.  I used river sand as my base.  It is finer than typical beach sand, packs nicely and creates a good base.  Then, I put beach sand on top.  I've had to add some over the past 3 years as it has worked it's way out but ultimatly, that is what I wanted.  Try cutting your bank back to a 15:1 (flatter) and re-try.

[lkb]

Thanks for the info guys.  The area where the beach is/was has some steeper slopes rising pretty quick as you get away from the water. Cutting it down to a 15:1 there would be a pill considering all the sidewalks and patio, etc. that I've already put in.

You know when you think about it the underwater retaining wall idea would probably end up getting the sand to about 15:1. If it just wasn't so hard to build a wall underwater. I would lower the lake level temporarily but I'm scared to since were in the middle of the worst drought ever.

[Horton]

At Ski West there was a lot of erosion right around the docks because . .  . I don’t really know why. What we did was build a sand bag breakwater under the dock. It seemed to really help.