Great we have permission, found the best location, did test holes and found that there is enough clay content, the watershed is of good clean water and have the pond outlined and grade stakes put in.
Now we can start moving the earth. First, get the top soil pushed out beyond the grade stakes. The most important part is in the dam area. If a thin layer of top soil is left, it will act as a drain. We did this as a test with one of the test holes that had been dug. The rain had filled the test hole but would not fill all the way. It would get to the top but a couple days later it would settle to the same height as last time. Once we got the water out we found the level of the water was right at the bottom of the top soil and the top of the clay.
Another point about top soil is it smells. Has a distinct odor, but the worst part is when the top soil is moved back to the pond area to seed for grass. With the top soil being mounded up in piles or layers, the sod or grass that has been buried will begin to decay. When pushing it back around the pond it will be stinky.
So far we have been looking at a cleared field for this pond. What if there are shrubs, brush, small trees or even large trees. All of these will need to be pushed away from the pond and cannot be used as fill. Even the root systems need to be dug out.
Here’s what happens. The roots or branches that are buried will in time decay. After the decaying process it will leave voids for the water to follow creating leaks for the pond or worse by eroding and possibly losing the dam. It is a hard decision to lose the big trees. The two reasons are from what has just been mentioned and when fall comes the leaves will end up in the pond. The decaying leaves will help to generate algae but having a tree nearby to shade the pond is also good to keep the pond cooler to help deter algae. So it’s like a catch 22. Just keep in mind a tree will search for water, so never have a tree near the dam or on the dam.
Pushing the topsoil beyond the grade stake leaves room to work and build the sides of the pond up to grade. Depending on the available space on your site keep the dam area clear of top soil piles or push them twice as far away from the dam area in case there is a chance of too much fill. Build these piles of top soil up on both sides of the pond, even below the dam area. Then the topsoil is nearby when moving it back to plant grass. The watershed is generally being cut down to grade so no sense on putting top soil there.