Did You Know … Winter Pond Repairs
Midwinter is often the time our farm ponds have their lowest water levels and when the surrounding ground is driest. It’s an excellent opportunity to check the pond’s physical condition and make any needed modifications and/or changes before springtime rains set in. In cases where ponds may have developed leaks, it’s a great time to move forward and seal them. The material below is taken from a guide published by the Southern Regional Aquaculture Center.
Water loss from a pond is a serious problem. For the farmer, it can mean little or no water for fish, irrigation or cattle. For the homeowner, a leaking or empty pond is unattractive and detracts from the landscape. Leaky ponds also increase water use, reduce fertilizer effectiveness, and can pollute groundwater.
The most common causes of leakage are: 1) improper pond construction; 2) permeable soils or layers with high sand or gravel content; or 3) thin layers of soil with fractured or layered bedrock or solution cavities (sinkholes) as their substrate.
Known problem locations include areas in north Alabama and Georgia, and parts of Kentucky and Tennessee, where thin soil mantles lie on top of cavernous limestone. Another area where ponds are prone to leaks is the Southern Coastal Plain region, where soils are sandy and usually have a limestone base. In arid parts of Texas and Oklahoma, subsurface caliche high in calcium carbonate or gypsum is associated with leaky ponds. The keys to repairing a leaky pond are properly identifying the cause of the seepage problem and selecting an appropriate method of sealing the pond. Though some treatments are suggested for undrained ponds, these are generally less effective. In most cases, a pond will need to be drained before repair. The purpose of the pond and the cost that the pond owner is willing to bear will influence treatment decisions. Because effective treatments often require an in-depth knowledge of soil characteristics, the pond owner should consult the Natural Resources Conservation Service (NRCS) or the Cooperative Extension Service for assistance.
Repairing a leaky pond is often expensive. When it is a viable option, re-working and compacting a pond is the cheapest alternative at about $300 to $1,000 per acre. Treating a pond with a minimal rate of bentonite (i.e., 1pound per square foot) will cost $3,500 to $4,000 per acre for the bentonite alone. Other treatments cost still more. The high cost of treating a leaky pond may lead the owner to abandon it, or do nothing in hopes that the pond will seal naturally.
In some cases the cause of a seepage problem may be apparent; in other cases, the cause may be unknown. When there is excessive seepage, the first step is to carefully examine the pond dam or levees. Seeps, wet spots or wetland vegetation on or below the dam are indicators of leakage through or under the dam or levees. Water also can leak through muskrat or crawfish burrows or through channels left by rotten tree roots. Older ponds can develop leaks around drain or overflow pipes.
If the water drops rapidly to a certain level, carefully check the perimeter of the pond at the waterline for holes or discontinuities in the soil. In addition to inspecting the pond, gather as much information as possible about the pond history, site characteristics, and construction practices used. Important questions include: 1) Was the site properly prepared by removing the existing vegetation and topsoil? 2) Was the pond levee built properly, in compacted layers of 6 inches or less? 3) Were the levee and pond bottom areas adequately compacted? 4) Is the area known for sand or gravel lenses or sinkholes? 5) How deep is the soil? 6) Is there fractured or jointed bedrock in the pond basin?
If possible, ask the person who built the pond about potential problem areas. This may help identify the problem area and reduce treatment costs. Before undertaking expensive pond renovation, consider that the problem may not be seepage. If the pond’s watershed has been altered or reduced in size less water may be flowing into it. This would give the misleading impression that water is being lost from the pond.
Sometimes ponds only appear to be leaking, or they may leak only temporarily. Ponds built in shrinks well clays will develop deep cracks when dry. As they are refilled water runs through the cracks until the soil swells again. A considerable volume of water may also be lost during the initial filling of a pond as it soaks into the surrounding soil, giving the impression of a leak. It is not uncommon for new ponds to have high initial seepage rates that decrease as microbial activity and the accumulation of fine sediment and organic matter help seal the pond bottom. If ponds that have sealed in this manner are dried or re-worked, they may again leak excessively until the seal re-establishes.
Information for today’s article was published as “Fact Sheet No. 105, Renovating Leaky Ponds” by the Southern Regional Aquaculture Center. The entire article can be located online at: http://srac.tamu.edu. For additional information, please contact Mike Frinsko, Area Aquaculture Agent, Jones County Center at: 252.448.9621 or firstname.lastname@example.org
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This article will be published in the Jones Post newspaper on January 17, 2013 and was compiled by Mike Frinsko, Area Commerical Aquaculture Agent.