How To: Fixing A Leaking Pond (Video)
Pond leaks are a very common pond management problem. Some leaks may be barely noticeable, while larger leaks can completely drain a pond. Unfortunately, fixing a leaking pond can be one of the most difficult problems associated with managing a pond. This article introduces the basic steps for determining if your pond is leaking and some tips for repairing leaks.
Causes of Pond Leaks
Pond leaks may develop from a number of causes. Probably the most common cause is inadequate construction of the pond bottom. Simply put, it is best to avoid a leaking pond by properly constructing the pond from the beginning. Areas of sand or gravel or fractures in bedrock that were not adequately covered with soil during construction may eventually leak.
Leaks may also occur around the pond banks or on the pond dam as a result of tree roots or muskrat holes. These leaks can be prevented by removing trees from the pond dam and by discouraging muskrats. In older ponds, leaks sometimes develop from outlet pipes that rust and leak below the water surface.
Finding a Pond Leak
The effort and expense necessary to fix a leaking pond is directly related to your ability to locate the source of the leak. Unfortunately, finding the location of a leak can be very difficult. Inspect the outlet pipe and drain pipe structures first to make sure that they are still intact. These structures often rust through in older ponds or ponds with corrosive water.
Leaks that occur on the pond banks or on the dam are sometimes easy to locate. Here, water leaving the pond may emerge on the outer surface of the pond, providing a clue to the location of the leak. Wet areas and growth of water-loving plants (like cattails) at the base of the pond dam or banks may be clues to the location of these pond leaks. Dyes may also be useful to locate these leaks. Sprinkling some solid, food-grade dye in the pond near a wet area along the bank may help determine if the pond is actually leaking at that location. Be careful to use small amounts of inert, food-grade dyes for this purpose.
Another characteristic of a pond with a leak along the bank is a rapid loss of water to a certain point, beyond which it then slows or stops losing water. In this case, the location of the leak can usually be found at or near the water surface somewhere around the perimeter of the pond. In the likely event that you cannot locate the general area of the leak, you will probably need to drain the pond and completely repair the entire pond bottom at significant expense.
Solutions for a Leaking Pond
In some cases, repairs to leaking ponds may require a permit or permit review. This is especially true for ponds that required an initial permit from the Department of Environmental Protection (DEP) Bureau of Dam Safety. Check with the DEP before proceeding with repairs on ponds that required construction permits
Make Up Water
In some cases, a simple solution to a leaking pond is to add water to the pond to make up for the lost water. This is usually only possible with very small leaks where a nearby spring or a groundwater well can be used to replace the lost water. Some pond owners use their home well to pump water to the pond during the night so it will not interfere with their normal use of water during the day. Such use of the home well for the pond should be done with great caution, especially during drought conditions. This additional pumping from your home well could dry up the well and cause the loss of water to your home. A professional hydrologist should be consulted to determine if your well could withstand the additional pumping during dry conditions. Also keep in mind that you may be required to register or obtain a permit for groundwater withdrawals to a pond if they exceed 10,000 gallons per day.
Compaction of Existing Material
If the existing bottom material contains a good mixture of coarse and fine particles, simple compaction may be adequate to slow or stop excessive seepage. The pond must first be drained and the affected area allowed to dry. The soil is then scarified with a rototiller or similar equipment to a depth of about 12 to 16 inches and then compacted with a roller. It is critical that the soil be compacted during optimum moisture conditions (i.e., not too dry or wet) to provide the best seal. The final compacted layer should be a minimum of 6 inches thick in the shallow areas of the pond and 12 inches thick where the pond is 10 feet deep.
If the existing soil is too coarse (i.e., too much sand or gravel), clay can be added to provide a better seal. The added material should be at least 20 percent clay. Luckily, adequate clay may even be available near the pond site. The clay should be spread in layers at least 6 inches deep but preferably one foot deep. Again, the depth of clay is related to the water depth. Deeper portions of the pond, where water depths exceed ten feet, should have at least 12 inches of clay after it is compacted. The clay should be compacted while it is at optimum moisture. It is important that the clay not be allowed to freeze or dry before the pond is refilled with water. Dry or frozen clay will crack and ruin the watertight seal. The exposed clay can be protected with mulch or straw to prevent this problem.