Pond question

[Legdoc]

I have pumped out my 150'X175' 3' deep pond. I plan to excavate it to a filled depth of about 8'. I plan to build a pier out to about 30' from the bank using 6"x6" posts. The soil is black clay. Should I concrete the posts?, pack the soil back? Please advise me.
Legdoc

[Rusty]

My pond is about 1/4 acre, with a filled depth of about 11'. I have a 3-section homemade dock that extends about 24' out from the shoreline. The three sections are bolted together and supported by 4x4 legs at the section ends. The longest legs are in about 5' of water. The legs are pointed and were driven slightly into the clay bottom with a sledge hammer. Penetration is minimal. The legs are cross braced. The dock has been in this pond about 10 years, and was in a river for close to 10 years before that. The dock does rise in the winter when the pond freezes, but generally drops back into place in the spring. Usually, my weight at each post is enough to reseat it. I haven't used the sledge hammer on it in years.

[gerard]

Since you're not putting any real weight on them I'd suggest just throwing a bag of concrete in the bottom of the whole OR using a solid concrete block to set the post on (2x8x16 or something similar). That will give the post a bigger footprint while still allowing you to easily pull the post out in the future if you need to. I think concrete is fine for a permanent installation where you have a lot of lateral forces like ina pole barn but I don't see the need for a dock/pier and there are schools of thought that say concreting a post rots it out quicker....

[ToadHill]

I went with a floating dock. It's easy to get out when it needs work, just hook it to the front end loader and lift one end on shore and drag it out.

[Dargo]

My dock with a 15' walkway going out to it has been in place for about 10 years now. It is completely supported by 6X6 treated posts that I just used a 80 pound bag of concrete at the bottom of each post. There ended up being some concrete under each post (but not much) as I used the dry mix to help level each post. Last year we had a severe drought and the water level in my lake dropped almost 5', exposing much of the posts. Surprisingly enough, there didn't appear to be any rot at all in the posts; especially the parts that were under water. I used a screwdriver and just scratched one of the posts about 3' below where the waterline was and it still looked green and like new just under the surface.

Even though I've treated the deck surface of the dock each and every year with wood preservative, I'm guessing I only have a few years left before I need to replace the decking. I really hoped it would have lasted longer with me taking the time and expense to seal it each year. I guess I should be happy that the rest of the dock, that would be harder to replace, is in great condition.

[ampsucker]

often misunderstood fact about wood: it only rots quickly when allowed to alternate between wet and dry. wood that is always wet will last many, many times longer than wood that is allowed to weather. same with very very dry wood.

case in point, divers are harvesting logs that were logged around the turn of the last century and sank to the bottoms of waterways on their way to the mill. these logs are highly valued because they are old growth forest logs of which there aren't many (any they are allowed to log) left. the logs are in pristine and well preserved condition. the old growth grain is beautiful and sought after for expensive furniture, veneers, etc. even common woods like oak and hickory do not look the same now as they did "back in the day".

that said, i'm in the floating dock camp. easy to move around if you want, easy to drag out to do maintenance, moves up and down with the level of the water, hey, you can even pole it out to the middle for a fishing platform if you make it quick disconnect.

common floats are styrofoam (closed cell) or some kind of plastic or metal barrels that hold air and won't leak. if you want to minimize maintenance, don't use wood above the water line as it will rot very quickly in a wet/dry environment. also, keep the center of gravity low so it won't be tippy.

amp

[EddieWalker]

I'm going to build a floating dock on my pond. The best prices that I've found online are at Overton's - Dockmate Float Drums 12-16 Height - Dock & Mooring > Dock Floats & Drums : Boat Mooring Equipment, Boat Dock Supplies, Parts, Docking Accessories , but the problem of how many floats and what level of boyancy has me scratching my head. I've done some design ideas and have 192 square feet of decking in my plan, so the question is how much boyancy do I need? Right now, I'l looking at 23 pounds per square foot, which should be plenty. That's 4,430 pounds with four floats at a cost of under $500 from Overtons.

I've gone back and forth on posts and decided against them when building my pond. I know they will last a very long time and are pretty standard in allot of docks, but I also know that there is a limited lifespan on them that I want to avoid.

If you are set on posts, it's more important to stabalize them with cross bracing then cementing them in the ground. Cement is used to force the post to stay in position. Just think of a fence and how the cement or compacting of the soil is all that keeps it in place. With a dock, you have the ability to brace it so that it does not matter what the soil conditions are like, or how soft it is. If the post does not sink, the sides really don't need any concrete or compacting with X bracing.

Putting a disk or sack of concrete at the bottom makes sense. Just be sure that it hardens in place before the pond fills so that it is actually supporting the load of the post. 4 inches is usually thick enough for concrete to have maximum strength, but I'd go 6 inches or more to make sure. It's not that much more money, and good insurance. As for the sides, fill them in with dirt.

Eddie

[sperry]

Up here in the north we are better off going with floaters. In winter Mother nature likes to play with docks up here! Much easier to maintain docks if you pull them every year. (As in, almost no maint) About 85 deg and high humidity up here today, dock time sounds good!!
Good luck with the project.
Sperry

[Dargo]

Originally Posted by EddieWalker

I'm going to build a floating dock on my pond. The best prices that I've found online are at [url=http://www.overtons.com/modperl/product/details.cgi?i=87017&pdesc=Dockmate_Float_Drums_12_ 16_Height&cname=Dock-Floats-Drums&aID=25L&merchID=1009&r=view]

I had a floating dock made professionally at my last house. Unless I really needed to pull it out in the winter my strong preference is for a true secured dock built on anchored posts. Even though my dock was engineered and built to hold 30 people on it, it would really move and if three decent sized guys sat on the front with their feet over the edge the dock dropped by about a foot on that front edge. Kids and elderly really had to hold onto something if people were moving around on the dock. That dock was a huge 15' X 25' dock too! For me, it just moved way too much with people moving around on it. Again, it's personal preference, but I strongly disliked my floating dock for the reasons mentioned above.

[ampsucker]

bouyancy is equal to volume of water displaced. you need to know your weight of the dock plus people or things stored. then figure the volume of your flotation. roughly, figure 8 lbs of water per gallon. convert gallons to cubic inches or liters or cubic feet - whatever unit you use to figure the volume of your flotation. that is the amount of weight it will float. don't forget to include the weight of the flotation itself. you may have to do the calcs a few times to zero in on the actual number since the depth to which the floats actually float is the amount of water displaced.

a well designed dock has most of the flotation under water completely so the center of gravity stays low. that helps eliminate the movement of the dock when everybody gathers to one side and makes it less "tippy".

amp