Life Expectancy of a Pond; The Aging Aftermath

Life Expectancy of a Pond; The Aging Aftermath
By Mike Otto

The actual work has not changed much since I saw the first dump truck full of muck and mud pour out on the ground those many years ago.

When we see cattails, reeds, lily pads, and lotus pads, we see indicators of siltation. That’s where those plants grow.

What happens when a pond starts to fill in with surrounding sediment? Upstream dirt begins to move downhill and stops as soon as it gets to our pond. Over time, sometimes slowly or sometimes quickly, water starts to disappear, replaced by added shoreline, reduced depth, and wetland plants pop up everywhere. Small trees and brush appear, and the area that used to be water is no more.

The newland created is as natural and common as anything that goes on anywhere on the planet. This phenomenon happens every time it rains in every stream and river. Just ask New Orleans.

The business of removing this material is a large operation in some of the major navigable waterways and bays of this nation.

You can see encroaching plants moving into the water column, along with dense plants growing in the water. Signs of heavy siltation and shallow water.

Over the last decade there has been a construction project in China that has dammed up three rivers. It is considered one of the biggest dams ever built. One of the concerns keeping engineers busy was how to deal with soils carried into the new lake, silting the bottom, and decreasing volume of the reservoir. So, the situation of a lake filling with silt is not new and is an ongoing concern for the largest lake on the planet, as well as the small ponds on our property.

Growing up working in the golf course construction business as a youngster drilled into me the importance of cleaning out of the ponds. That practice is a constant exercise; it must be done to keep the place looking good, and in many cases, to keep the pond volume where managers want it. The actual work has not changed much since I saw the first dump truck full of muck and mud pour out on the ground those many years ago.

Part of the silt removal is de-watering. That’s the most efficient way to get to silt and move it quickly.

So, you have an old, heavily silted pond? You remember the vibrant pond of your youth, loaded with fish, and those fun times when you and your buddies caught fish, swam, and had a good time? Now, fast-forward a few decades and that same pond seems much smaller (which it is) and overgrown with cattails, buttonbush, and underwater greenery to the point it looks stagnant.

Want to fix it?

Here is the short story. Drain the water (sometimes), move the gooey, pudding-like material to a place it will not flow back into the pond, and do any other shaping work that needs to be done when the water is gone. Get the mud smoothed and graded, then plant some grass, and pray for rain.

That sounds easy, doesn’t it?

Really it is, as long as you have the right equipment and a good plan with a budget that is impossible to pin down. Heavy on the phrase, “Impossible to pin down”.

I know, lots of work done on a piece of land, and especially around your pond can be done by anybody that wants to be outdoors and have a little fun. Really most of the readers are the kind of people that enjoy doing projects.

Bulldozers may push muck to a trackhoe, which picks it up and tosses it over the dam.

Pond renovation is not one of these projects. Experience is needed along with specialized equipment that most people do not have. Time can also be a factor. Unless there is some way to keep the rain out of the way, the project is usually done at a pace that most people do not have. A weekender that needs to be somewhere making a living cannot dedicate the time needed to get this work done.

This process starts by gathering of as much information as possible, and then making decisions. Some of the decisions are made in the moment, surrounded by stinky muck, while others take some thought and planning.

A trip around the shoreline is a good place to start. It will tell where the water is coming in and shows the beginning of the work that needs to be done. The first thing to look out for is shallow water, cattails, waterlilies, and willow trees. They are usually the first to move in. They come with the dirt and are Mother Nature’s tools to change water into dirt.

Wherever possible measure the depth of the water and compare it to the original depth. In yesterday’s world, paddling a boat out, with a piece of rebar or half-inch PVC pipe shoved through silt, down to hard soils on the pond bottom gave us an idea of silt volume and location. Today, sonar units quantify much faster and more accurately. This will tell you how much material has been deposited across the entire pond and needs to be removed.

Silt migrates to the shore, then downward, into the pond bottom, making it shallow.

This information is valuable, before the real work begins. The problem is it may not be as easy as it sounds to determine the exact amount of the material. A case in point: A good friend, Paul Cannon and his wife, live out in the country close to a major North Texas city. Their first place was a beautiful home in a small country estates-type setting with a small pond that did not hold water at all. It had the watershed drainage but not the material, although it did grow great grass and healthy trees. A move was made to another location with an existing pond. From past experience they presumed it was easier to build a new house than it was to get an old pond to hold water. The new place is as great as the old place, but a little farther out in the country without a paved road.

The pond had been tested and proved good for holding water. Even though it may not be full all the time, it had good possibilities.

The land was fenced, a new home was built, and then it was time to work on the pond. Their wet spot sits in a beautiful location close to the back porch and in the middle of a stand of healthy oak trees. At first glance Paul knew it was not very deep. It appeared to be at least 30 years old, based on map history. We got in his boat with a pipe and started the fact-finding process all around the edge and out to the middle. There was only about a foot or two of washed in mud according to the probe. Maybe we should have used one of those new-fangled sonar units.

Water was drained, machines moved in, and the work began. Two days later seven feet of mud was removed. The initial exploration was not accurate. It was done by yesterday’s book but did not tell the whole story. Today the project is completed, but it grew after it got started. This is not out of the ordinary; as a matter of fact it seems to be the norm, even with some of the newest technology.

The bulldozer pushes as best it can, to set the table for a trackhoe to move it out of the pond.

The biggest question during planning this type of project is, “What is done with the mud when it is removed, and how is it handled?”

Silty material is about 30 percent water, which makes it the consistency of catsup. It will not stay in a pile. It actually moves like cold, smelly lava. Once out in the open, subjected to sunlight and air, it starts to dewater quickly and stops moving after about 24 hours. But, it may take as long as a year for it to dry out enough to drive a vehicle across, but with sun and wind it will eventually turn back to dry dirt. Keep this in mind with silt: it must be pushed downhill. It is almost impossible to push mud uphill. It just will not work. It may be necessary to put the material in dump trucks and haul it away. Whatever the case, do not fight gravity when dealing with mud and muck.

Often, a good location for mud is behind the dam, if there is room. If it can be stored behind the dam it will not run back into the pond. That is the first place to look. A dozer or loader can push the material downhill to the dam and a track hoe can lift it over the top, dump it, and gravity will pull it away where it can dry, and then be mixed with other soils and spread out. This technique is easy and done every day, if there is room.

If there is no room behind the dam, look for a spot as close as possible to the work area. This is where dump trucks come into play. A trackhoe or loader will be needed to load trucks. It is important for trucks to be located where it is easy for them to come and go. It may look like a dog chasing a car for a little while as the dump trucks get started, but with a little time it will turn into the likes of a college marching band.

The trackhoe picks it up and tosses it over the backside of the dam.

Any place close to the clean out will work, provided the mud does not block the natural flow of water. A terrace may need to be built in order to get started and keep the mud where it belongs. Keep in mind that the cost of a project will depend on the time (and distance) it takes to move the mud—and how many times it must be moved.

A small tractor with four-wheel drive and a loader can move a lot of material in a day. If you have one, and the conditions are right, get started. There are dozer guys everywhere that will be glad to give you a few pointers.

Here are the main points to consider. If you have a pond that has lived its life and you want to resuscitate it, get your best estimate on volume of silt to be removed. Have a plan where to move the silt, and the best way to do it. Look at the costs. You may find it to be much more costly than building a brand new pond on another site on your property. But, if it’s economically feasible, and you have a good place to move the silt and can do it efficiently, then it could certainly be worth the effort.

Besides, what’s it worth to bring back that pond of your childhood memories?

A good method to move silt is to start at the edge, mix it with solid soils and push it to the finish line.