Rural landowners often get a good look at the bottom of their ponds during winter and particularly after a drought. After doing so, they might be considering corrective actions such as cleaning sediment out of the pond or adding sealants. First there are some questions one needs to consider before deciding to clean or amend a pond:
- Should I clean a pond or make a new pond somewhere else? What is the purpose(s) of the pond? What is the pond’s value (how much are you willing to spend) for the intended purpose? Is cleaning a pond the best option for a water supply?
Ponds are expensive to build; some leak in spite of corrective measures; they occupy valuable land; unless fenced, ponds are a risk to livestock loss in winter; and they require considerable maintenance. In the absence of a reliable cost from a local business person, a good estimate is $10 per cubic yard to clean.
If a suitable site is available, it is usually less expensive to construct a new pond than to clean sediment from an existing one. Thus, a new pond should be fully considered before deciding to clean one. Be sure to include fencing the pond and providing a remote watering site in the cost.
Many ponds were originally built for livestock water supply. They may have been the best option at the time. But, is a pond the best option for the purpose now? For information on alternatives, see K-State Research and Extension publication S-147 Waterers and Watering Systems: A Handbook for Livestock Producers and Landowners at: http://www.ksre.ksu.edu/bookstore/pubs/S147.pdf For example, a solar pump in a well might be less than half the cost of a new or cleaned pond and would have better quality water.
- What to do with sediment?
Placing this on the back side of the dam is the best and recommended place. You could also use some of the sediment to fill low spots, small gullies, or ruts on the property. - Where should you avoid placing the sediment?
Putting it right next to or upslope from the pond is not a good spot because it could wash right back in.
- Using it as a building or topsoil material
Pond fill will not have any soil structure, so it will have very little strength. It is probably not a good idea to use pond fill under a supporting wall of a building, but it
Why is my pond dry?
There are a possible few reasons. After a drought it can take a few years for the water table to be replenished, so even ponds that once held water will take a while to recharge. If this is a new or newly-renovated pond, it’s possible that there is either a structural problem or that there is not enough clay in the soil. How can you tell if a soil has enough clay?
Moisture-by-feel test: Roll out a small clump of soil into a wire. The ideal soil/moisture condition would be for it to roll out to 1/8-inch diameter without breaking or crumbling. If it breaks, rewet it. If it still does not roll out to 1/8-inch diameter, it may not contain enough clay, and therefore, might need a soil additive.
Sealing Lagoons or Ponds: Dispersants
Dispersants work by causing clay particles to swell and repel each other, thus destroying soil structure. All dispersants are to be incorporated and compacted in six-inch layers during the construction. (Adding the dispersants to an existing pond may not work).
Sodium Bentonite
Application rate: 1-1.5 lbs/sq. ft. (silty soil)
2-3 lbs/sq. ft. (sandier soil)
Notes: Most expensive option
Soda Ash
Application rate: 10-25 lbs/100 sq. ft.
Notes: Makes a good seal. Soil must contain >15% clay, and >50% clay + silt
Rock Salt
Application rate: 20 to 33 lbs/100 sq. ft.
Notes: Least expensive option. (One reference suggested rates as high as 4 lbs per sq. ft. during new construction would not harm fish or inhibit vegetation).
Assessing soil compaction: Soil penetrometer
Cone penetrometers are often used to locate compaction. The penetrometer rod should be driven in the soil at a rate of approximately 1 inch per second.
Level at which root growth is impossible: 300 p.s.i.
Lagoons and ponds should be compacted to between 625 and 725 p.s.i.
DeAnn Presley, Soil Management Specialist
deann@ksu.edu
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