Pond Boss Forums GENERAL QUESTIONS Property Projects & Construction A few questions about a botched pond job

Hey guys, just looking for some input to a few of my questions since I'm learning on the fly here.

So I had a contractor dig a pond that was supposed to be swimmable on my property in VT that was supposed to be 40x60 and 9 feet deep, fed by rain/gutters. The soil is sandy (soil type A I believe now) so we needed clay. Contractor dug the pit and then brought in blue grey clay to line the pond (1 foot thickness).

The pond ended up only being 5 and a half feet deep so we got into an argument. However, I don't think this was the only big detail that he overlooked.

1) After the clay is spread, should he have applied a layer of soil over the clay?

2) Should the clay layer be smooth without any excavator/skid steer tracks in it?

3) Should there be a clearly defined pond edge? Problem here is that there is a steep slope above the pond and I can just see lots of runoff coming off of it straight into the pond.

4) Should something go under the packed clay? I think its called compaction or something?

Sorry if I missed any details about the pond, as I'm very new to this and worried that I just have an expensive hole in the ground currently. It is filling up with rain water (currently 2 feet deep), but I'm just very worried that I'll have major issues with water quality.

Welcome to Pond Boss. A bit over my experience level but wanted to at least /wave hello!

I tried to directly answer some of your questions above. I am going to add a little more general discussion.

I believe clay shores are going to be miserable for a swimming pond, and perhaps even dangerous. You MUST have at least one spot on a swimming pond where the slope is gentle enough, AND the bottom is firm enough for a child to be able to walk out of the water!

Can you walk barefoot into the portion of your pond that has water now and see how much you sink in?

A "fun" swimming pond also requires a fun way to access the pond. Are you going to add a little dock so people can walk out to deeper water and swim without getting their feet dirty? If so, you must have a prominent "No Diving" sign for a pond of that depth.

The other option would be to add a small sandy beach. Kids and adults like that method to enter deeper water, and it is enjoyable to sit on the sand in shallow water.

Is there now a large area of barren ground surrounding the pond? If so, you need to get your preferred groundcover planted ASAP. The next heavy rain will start eroding the bare ground and it will go straight to the bottom of your pond. A 5.5' deep pond can quickly go to 5'.

Do you have another water source to fill the pond right now? In your shoes, I would fill the pond now and check the function of my water outlet. I would also mark the edges of the pond at "full pool". You can then determine if your pond leaks! If not, then you can start doing all of your additional work landscaping and finishing the swimming enhancements of the pond to get close to an attractive and useful swimming pond.

Just throwing out some ideas for you to consider. Good luck on your project!

Good comments by FishinRod. In addition.
1. If it was my pond I would want the clay bottom as smooth as possible. If it were mine I would not put soil on top of the clay. Soil will also contribute to muddy water conditions, more water fertility nutrients, more early growth of algae due to more fertility nutrients in soil vs clay. . A smooth bottom is a sign of well compacted tightly sealed clay. Tracks in the bottom layer suggest, IMO just suggests, to me to indicate the clay was not well compacted. The smoother the bottom is IMO this means hard well compaction. Quality of compaction really depends on as FRod says moisture content of the clay and type of equipment used for compaction. Dozers and skid steers are not compaction machines, they are designed to float and not sink into the ground,. Good equipment operators should know this fact.

Your question. "4) Should something go under the packed clay? I think its called compaction or something?" I am not sure what you mean by this question. Compaction is a process where clay layers are forced together to make a thicker blanket clay layer. Ideally the individual clay layers are knitted together so water is less likely to seep between the clay layers. For a clay liner or seal,, layers of clay (often each 4"-6" thick and called lifts are sequentially compacted on top of the first lift compacted layer that is worked into the more lose soil below the 1st clay lift. The more lifts are added and compacted together as one thick unit.

3. I agree fill the pond asap to overflow level then watch how fast the water level drops. The longer the banks stay dry the more they can dry out and then cracks form in the clay liner. When the cracks later water gets on top of them the crack is a crack and not a well mended together area as originally created & tight compacted. Cracks are not compacted when they fill with water and eventually lose sediment.
I think if the pond receives 3/4"-1" of rain each month,,,, 'generally' the pond should stay at full top level if it is a very well sealed pond. All clay/ dirt ponds leak. The degree of leakage indicates how well they are sealed. In breezy hot dry 85F-90F temps and no rain,,, evaporation can be up to 1/4"-1/2" per day up to 3" per week. The degree or amount of evaporation is called pan evaporation i.e. amount of water that evaporated per day in a pan of water.

4. If the pond does not have a swim beach, (often 4:1 or 5:1 slope) and all sides are steep sided 3:1 slope then a beach entry area can be made. Just back up a truck loaded with sand or pea gravel to the pond and dump it at the shoreline where you want a beach. Then manually work the material into the pond as wide as the pile of material. Over time the material with usage will work further and further deeper down the pond bank.

5. As the clay bottom remains underwater it gradually becomes softer and softer and less slippery. IMO the softness allows one to get some traction to climb out and back to the water's edge.

6. Water shed runoff into the pond will contain suspended dirt and clay - natural erosion. Water draining into the pond from the watershed helps fill the pond with excess rain water. This is why the watershed area should get planted to a thick grassy like cover crop asap.

As Bill notes, some equipment (dozers, skidloaders) are made NOT to compact. However, if a pond has vibrating sheeps foot roller ( a great compacter) tracks on the bottom, that's a good thing. If the clay was compacted, something had to have done it, and I bet it left some kind of tracks.

Theo is correct. Clay compacted with a sheepsfoot compactor will have 4"-5" wide and 4"-6" deep 'divot type holes' all over the bottom from the sheeps foot roller compaction device. By a smooth bottom of a newly built pond, IMO it should not have large or soccer ball sized chunks of dirt/clay all scattered around on the pond bottom. Those larger clay chunks should have been smashed flat during final compaction. If I posted pictures I would show you want a bottom compacted with a sheeps foot looks like.

The negative of this:

Theo Nice picture. Thanks. Every pond builder should have one of these. IMO it is a NECCESSARY machine for pond building and clay compaction. If they don't have one or rent one they are not on my list of GOOD Pond Builders.

Excellent point!

In my area, they are not even that expensive to rent.

If done correctly the bottom should be very smooth as the compaction gets up optimal level the sheepsfoot should be compressing the ground less with each pass. I like to run it until the ground is smooth and develops a shine to it.

By the time it has a shine on it, you have definitely "walked out" the feet!

You can also pull a large sheepsfoot roller behind a dozer, but it won't be a vibratory one. The different lifts need to be knitted together with a sheepsfoot and not a smooth barrel roller. You will end up with a pond bottom that looks like pages in a book with a smooth barrel roller. Water can work it's way through each page, move horizontally until it finds another crack/fissure, go down a page, rinse and repeat until it leaks out of the pond. In a pond that has the lifts knitted together that won't happen - the water cannot move horizontally.