I'm interested in what equipment different people prefer for a waterproofing job. I plan on draining the pond and waterproofing with bentonite. I will till the required amount of bentonite into the top 4 inches then cover with a 2 inch clay cap and compact. Just list the equipment you think you would need from pumps to heavy machinery.
Site Description:
No dam
1 acre surface area when full
Max depth 10-12'
sandy soil
Job will be in South Georgia during the Spring
I've done jobs like this before, but always like to hear other opinions on procedure.
sas, what has your success rate been with using that thin of a layer? I was under the impression that the layer of bentonite/soil had to be much thicker.
I would till in a 6" layer of bentonite at least 12 inches, up to 18" deep using a disc harrow, add around 20% moisture content and compact with at leats sheeps'foot roller or best case, a large (37,500 lb)vibratory sheep's foot compactor.
I'm with you Rainman. Seems that a sheepsfoot would absolutely puncture a 4 inch seal. But 6 in of bentonite and a 18'' till seems to be alot of bentonite. These two processes differ tremendously in bentonite pricing. The soil is extremely sandy and the watershed is not very large. Pond to watershed size ratio is around 20:1.
SAS...that thread referred to a 20 foot by 20 foot pond only 5 feet deep....VERY little static water pressure.
Done properly and repeatedly, a sheep's foot roller reaches full compaction when the feet have pushed, mixed and compacted the soils to a near concrete state and the roller feet no longer sink into the ground more than a half inch or so.
The 4" layer of bentonite will be mixed and spread rather than punctured, but may not provide the strength or thickness to hold back the water pressure long term if an animal (muskrat/beaver), fish (catfish/carp/ nest builder), or inquisitive mud-patty-making child (all known species ) digs around a little and penetrates the seal.
Ah ha, gotcha Rainman. Thanks for clearing that up for me. This is an acre pond so .5 acre feet of bentonite? Seems pricey What do you reckon bentonite alone will cost? It's a dug pond so there isn't a dam. The water table is down due to the lack of rain here and the water level in the pond stays right at the level of the current water table. Do you think it will be worth waterproofing to get another 4 feet above water table level. Owners do have a groundwater pump but would rather not run it much if any. They stated if it runs 24hrs it barely stays full. It probably pumps ~80 gallons a minute.
One guy used a kitty litter plant and got the bentonite very cheaply. From the Bentonite mines, shipping would be pricey!
I'll stick with a higher amount of bentonite and deeper mix...if it fails, you have to do it again at even more expense...better safer than sorry. A 2-4" depth may seal and hold water, until something like I described happens...and sooner or later, it will.
Another option that could save you some money would to compact a thin 2-4" layer of bentonite and cover that with a foot or two of firmly packed soil as a seal protection.
Especially if you sift the soil as suggested to get it rock free...once the bentonite layer is compacted, the trash soil could be safely spread back out over the bentonite layer without punching through it.
I looked into bentonite for my groundwater dug pond in sandy soil and the cost was too prohibitive.
Didn't someone here have some totes of bentonite that they weren't using and wanted to let them go cheaply? I think they were down south somewhere. Or was that East??
Rainman, the seal protectant layer I think would be the way to go. I think it would be cheaper and keep the bentonite from suspending in the water column.
Dave, I am trying to convince my clients to hold off on the project until late summer when the water table is the lowest and the soil is the dryest.
Thanks for the input guys! I'll keep everyone updated on my progress.
So, I figured I would need around 5 pounds of bentonite a square foot. That works out to about 100 tons for my .8 acre pond. The best price I've got so far is around $200/ton, this price includes freight. Base on that price I'm looking at 20K in just material. I'm starting to lean to just compacting a good local clay... hmmm decisions, decisions
So, I figured I would need around 5 pounds of bentonite a square foot. That works out to about 100 tons for my .8 acre pond. The best price I've got so far is around $200/ton, this price includes freight. Base on that price I'm looking at 20K in just material. I'm starting to lean to just compacting a good local clay... hmmm decisions, decisions
In 2007 I came up with 30K for an 1.5 ac pond. That didn't include the price of digging the pond bigger from .5ac to 1.5 ac. It looks like prices haven't changed that much.
) digs around a little and penetrates the seal.
What do you reckon bentonite alone will cost? It's a dug pond so there isn't a dam. The water table is down due to the lack of rain here and the water level in the pond stays right at the level of the current water table. Do you think it will be worth waterproofing to get another 4 feet above water table level. Owners do have a groundwater pump but would rather not run it much if any. They stated if it runs 24hrs it barely stays full. It probably pumps ~80 gallons a minute.
