Hi team,

Putting in a one acre pond that will require a dyke / dam that will be approximately 6’ high. My pond contractor will be putting in an 8 inch PVC primary drain thru the dam. His proposed method is building the dam in 4-6” lifts compacting between lifts with his thin track dozer and manually compacting around the drain pipe. He does not use seep collars in his construction.

Should I insist on a seepage control device? If so, would 1 collar, 2 collars or a sand filter diaphragm be preferable? If the sand diaphragm, what size should the sand diaphragm be?

Thanks, Tony

It is very common in my area to just put a pipe in and smoosh the clay in around it and let it go at that...no real compacting, no thought of seep prevention, BUT we have excellent clays and moderate seasons. My small pond has a 15" corrugated drain pipe and the clay fill was just tapped in with a backhoe bucket...it does not seep a drop.

In your case, I would have to rely on the builder that is familiar with your area and, more specifically, your pond location. If they have a good reputation, guarantees the work, and says you don't need a seep collar then I would consider that good professional advise. The most important part of this is their reputation.

Welcome to the forums BTW,

The key in the above post is "guarantee the work". Personally unless you can make pottery from the clay I would not be comfortable in using the tracks on the excavator to properly compact the soil. The tracks are there to keep the machine from sinking into the soft ground, which is just the opposite of what you are looking for when compacting dirt.

As for the anti-seep collars, I would spec a minimum of one with the dirt compacted all around the pipe (bottom, sides and top), and preferably 2 anti-seep collars.

Just had a contractor out to estimate putting siphons through our dam. He recommended pouring concrete at least a foot all the way around the pipe as a seep collar. It also prevents the pipe from bucking and vibrating when the siphon starts and stops.