Three important features for pond construction are topography, soil type and water supply.The ideal topography for pond construction is a natural low area or a broad draw with a narrow neck at its lower end, permitting runoff and springs to be impounded with a short dam across the neck. The most economical pond construction site will impound the largest amount of water, with the smallest dam.
Pond construction for the dam, sides and bottom should be composed of soils that contain enough clay content. Properly compacted to provide a water tight basin, with no woody or organic material. Spread thin layers, approximately 6” thick and thoroughly compact, depending on the equipment used.
Pond Construction And Water Supply
The ideal watershed should keep the pond full at all times. Ideally springs or small seeps are the best source, they provide cool,clean, unpolluted water, but much in the way of supplying oxygen. But be careful these springs and seeps can also act as drain in the summer months. The runoff should come from tree cover or grassland. This will help filter silt and other pollutants from entering.
Pond Construction Of The Dam
The top of the dam should be 8′ wide for a depth less the 10′ and 12′ wide, going 20 to 25 feet deep. The slopes of dam side and grass side should be 3:1 minimum. 4:1 on grass side will be easier to mow. The top of the dam should be at least 12” above the overflow pipe level to help prevent waves and floods from over flowing the dam.
In pond construction terms this brings us to the mechanical spillway. Known as the overflow pipe or trickle tube. This maintains the the normal water level of the pond. It permits regular overflow to escape with out using the flood or emergency spillway. The top of the overflow pipe should be six inches to one foot below the emergency spillway. Pipe size should permit that the level returns in 24 hours. The over flow pipe can be combine with a drain tube. Having a drain tube allows the pond to be drained to either make repair if a leak should occur or to remove undesirable fish populations. With any pipe going threw the dam the use of a anti seep collar should be placed 10 to 25 feet apart. Decide if you want a drain before starting the pond construction.
Pond construction And The Spillway.
The purpose for the flood or emergency spill way is to safely remove excess water during heavy rains. It should be big enough to handle the 25 year rain. Wide and shallow works best , this allows the maximum flow and the least amount of fish loss. The spillway should be gentle sloping away from the pond. Can be seeded for grass, cement, anti erosion screen or rocked to help prevent erosion. Do not screen the spillway in an attempt to save fish. It is cheaper to lose a few fish than to lose the dam.
Plan your pond construction carefully.
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