Pond Boss Forums POND CONSTRUCTION Building a dam building the dam

The pond builder has been digging my pond for the a few days now. The dam will be about thirty foot tall and 100 yards long. He is using two tracted (T300) Bobcats
and a sheeps foot roller (CAT). Will this type of eqipment compact the clay enough to hold water in my pond ? I'm kind of worried.

Thanks for any help.

The sheeps foot roller is the best tool for compacting dirt.

Sheepsfoot rollers are the right equipment for clay but equally important is the water content pf the soil and the thickness of the lifts along with the number of passes.

the only other issues will be soil quality (clay content) and application.
A T-300 is pretty small WRT capacity to move volume. 2 of 'em isn't very impressive, either. I relent to the dirt guys here, but a job of the size you describe, IMO, may be better done with MUCH larger equipment. How are you being billed (if I may ask). I would be concerned for efficiency vs. cost. Are there any plans for larger equipment, scrapers or earth movers?

Brettski- Size doesn't necessarily mean more efficient. My excavator used a 277B Cat as much as he did the D8 dozer. The smaller machines may not move as much material in one shot, but they will smoke the larger machines in travel time. Fuel costs are also much lower with the smaller machines.

Thanks for your Quick reply. They cut in about a foot wide by six foot deep key way, then started adding clay at about a six inch layer at a time then packing it with the sheep foot roller.Its taking longer than they told me it would take but he bid the job at a flat rate , not by the hour. I've got another thing to ask you guys. He wants to use three six inch culverts through the dam at the top and go down the back under ground to the bottom of the dam instead of using a twelve inch as he planed in the beginning . Do you guys think this will be alright. Water level would be less than a foot from the top of the dam. It will also have a concrete spillway going over the top of the dam . Any advice?

The idea to distribute the outflow amongst multiple principal spillway pipes makes sense in as this allows "back-ups" if one becomes clogged...particularly during a gulley-washer. The issue then becomes focused on each pipe to determine it's potential to become clogged. If there are no trees around the pond (leaves, sticks) or any other potentials for obstruction, I imagine 6" splillway(s) can be reliable....? Is it possible for one fat Cat to plug the hole? (I'm having issues with the 6" pipe...maybe it's just me.)
The opening of one 12" spillway is 113 sq inches. Three 6" spillways is 85 inches.
All of these calculations correspond directly to inflow/outflow. What is your pond size in acre/feet and surface acres? What is your watershed size?
Usually there is at least 24" more dam height above the top of your emergency spillway. I presume the concrete spillway is your emergency. I would expect 24" more dam height above this structure on the balance of the dam.

newbe1,

Brettski makes good points relative to the reduced area of the 6 inch pipes and the 1 foot safety margin.

Often there is an opportunity for two natural spillways in a pond construction (at least in most excavated ponds I'm familiar with). They are always located where the dam tapers to meet natural ground on both sides of the pond. Sometimes the lay of the land can preclude these natural opportunities. If you have an opportunity to have one or two of these natural spillways, it could be a good thing, either as emergency or primary spillways.

It just makes me uneasy to have a plan which relies on water flowing through or over a dam to provide surge protection...of course, I live in a climate where we go from drought to 100 year floods over a weekend as is happening now in parts of Houston. Our twice a year 100 year flood is currently in progress in some parts of town.

Just to clarify some of your dam design information.
1. Proposed finished dam height is about 30 ft.
This is tall for a structure in most States.

2. Proposed freeboard (height above Principal spillway or tubes) is only 1 ft.?
Consideration should be given to future settling, erosion, wave action, etc. I wouldn't go anythin less than two ft. and probably three ft. would be better.
3. Propose using 6" tubes opposed to 12" tube?
A 12" tube would be a minimum as mentioned by others on this forum. A 6" pipe will easily plug; Also each tube should have at least one anti-seep collar installed.

4. Proposed emergency spillway is concrete spill over top of dam?
I guess I would prefer to go around the side of the structure with an earthen emergency spillway. How much concrete were you going to use?

Just my $.02.

Ed

Brettski,

I've had a dead racoon plug up my six inch pipe during a snow melt. Water was about 2 feet over pipe before I discovered it and got it out. Sounded like Niagara Falls when the water finally went rushing out!

I like it when Ed posts...no bones about it. Newbe 1, just click on Ed's name and check out his occupation. His $.02 will earn quick interest.
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Fishraker averts a potential disaster: whodathunk? Well, DD1, now we know "what gitz the coon".