Clarkekoi
Structural
- Jun 26, 2005
- 1
I construct koi ponds for a living. I have had good success making a rudementary concrete collar to support the landscaping rock. The collar is generally 8 - 10 inches wide and 5 inches deep with reebar support. I'm not a concrete engineering expert.
Our current job is in sand like I have never seen before. There is little support and I expect the collar to sink and be undermined due to the fact that the pond is situated in a watershed area. The rock is large area wise, but not overly thick. Some stones are 6 feet x 4 but most are a little smaller, all are about 6 inches thick. I expect to pile the rocks 2-3 high(1/2 will be in the pond thereby making them lighter). Any higher than that and we will be pouring pads with footings - waterfalls.
So now finally the question, I don't want to have to do a continualy pad and footing to support the rock around the entire pond (60 feet long pond). I'm planning to make the collar a little wider to spread the load better, add more reebar than the normal dual staggered, try to compact the soil with a tamper and perhaps use a mini auger to drill down an additional 2 feet to add small footings ( 4 inch wide) every 2-3 feet along the run of the collar. I'm also concerend about the back end of the stone possibly sinking. The collar is actually at the front edge of the pond - the rock will cantilever over it about 1 foot give or take, so the bulk of the rock will be behind the concrete collar and placed on the sandy soil. Planning on getting the excavator to compact that area and I also plan to install some drainage with sump pump in behind the pond as I suspect the water is a big source of the problem...(this is a rebuild, and the existing stone is all but falling forward into the pond and the soil has collapsed forward behind the liner - the previous builder had no pads or support at all in place)
Should I add some gravel under the collar ? Should it be wider rather than thicker ?
any suggestions greatly appreciated, thanks for reading all this...
regards....
Our current job is in sand like I have never seen before. There is little support and I expect the collar to sink and be undermined due to the fact that the pond is situated in a watershed area. The rock is large area wise, but not overly thick. Some stones are 6 feet x 4 but most are a little smaller, all are about 6 inches thick. I expect to pile the rocks 2-3 high(1/2 will be in the pond thereby making them lighter). Any higher than that and we will be pouring pads with footings - waterfalls.
So now finally the question, I don't want to have to do a continualy pad and footing to support the rock around the entire pond (60 feet long pond). I'm planning to make the collar a little wider to spread the load better, add more reebar than the normal dual staggered, try to compact the soil with a tamper and perhaps use a mini auger to drill down an additional 2 feet to add small footings ( 4 inch wide) every 2-3 feet along the run of the collar. I'm also concerend about the back end of the stone possibly sinking. The collar is actually at the front edge of the pond - the rock will cantilever over it about 1 foot give or take, so the bulk of the rock will be behind the concrete collar and placed on the sandy soil. Planning on getting the excavator to compact that area and I also plan to install some drainage with sump pump in behind the pond as I suspect the water is a big source of the problem...(this is a rebuild, and the existing stone is all but falling forward into the pond and the soil has collapsed forward behind the liner - the previous builder had no pads or support at all in place)
Should I add some gravel under the collar ? Should it be wider rather than thicker ?
any suggestions greatly appreciated, thanks for reading all this...
regards....
