Common Problems With Farm Ponds

Introduction   |   Fish Kills   |   Muddy Water   |    Leaking Ponds   |   Wildlife

Leaking Ponds

• Page 1 - Leaking Ponds
• Page 2 - Compaction
• Page 3 - Clay Blankets
• Page 4 - Bentonite
• Page 5 - Chemical Additives
• Page 6 - Waterproofed Linings

Click here for a printable version of this publication: Sealing Leaking Ponds

Chemical Additives

Because of the structure or arrangement of the clay particles, seepage is often excessive in fine-grained soils. If these particles are arranged at random with end-to-plate or end-to-end contacts, they form an open, porous, or honeycombed structure, and the soil is said to be aggregated. Applying small amounts of certain chemicals to these porous aggregates may result in collapse of the open structure and rearrangement of the clay particles. This dispersed structure reduces soil permeability. The chemicals used are called dispersing agents.

The soils in the pond area need to contain more than 50 percent fine-grained material (silt and clay) and at least 15 percent clay for chemical treatment to be effective. Chemical treatment is not effective in coarse-grained soils.

Although many soluble salts are dispersing agents, sodium polyphosphates and sodium chloride (common salt) are most commonly used. Of the sodium polyphosphates, tetrasodium pyrophosphate and sodium tripolyphosphate are most effective. You can also use a technical grade soda ash (99 to 100 percent sodium carbonate). Sodium polyphosphates are usually applied at a rate of 0.05 to 0.10 pound per square foot and sodium chloride at a rate of 0.20 to 0.33 pound per square foot. Soda ash is applied at a rate of 0.10 to 0.20 pound per square foot. A laboratory analysis of the soil in the pond area is essential to determine which dispersing agent will be most effective and to determine the rate at which to apply it.

Mix the dispersing agent with the surface soil and then compact it to form a blanket. Thickness of the blanket depends on the depth of water to be impounded. For water less than 8 feet deep, the blanket should be at least 6 inches thick. For greater depths, it should be 12 inches thick, treated in two 6-inch lifts.

The soil-moisture level in the area to be treated needs to be near the optimum level for good compaction. If the soil is too wet, postpone treatment. Polyphosphates release water from soil, and the material may become too wet to handle. If the soil is too dry, add water by sprinkling or wait for a light rainfall.

Clear all vegetation and trash from the area to be treated. Cover rock outcrops and other exposed areas of highly permeable material with 2 to 3 feet of fine-grained material. Thoroughly compact this material. In cavernous limestone areas, the success or failure of the seal may depend on the thickness and compaction of this initial blanket.

Apply the dispersing agent uniformly over the pond area at a rate determined by laboratory analysis. You can apply the agent with a seeder, drill, fertilizer, spreader, or by hand broadcasting. The dispersant should be finely granular, with at least 95 percent passing a No. 30 sieve and less than 5 percent passing a No. 100 sieve.

Thoroughly mix the dispersing agent into each 6-inch layer to be treated. You can use a disk, rototiller, pulverizer, or similar equipment. Operating the mixing equipment in two directions produces best results. Thoroughly compact each chemically treated layer with four to six passes of a sheepsfoot roller.

Protect the treated blanket against puncturing by livestock. Cover the area near the high-water line with a 12- to 18-inch blanket of gravel or other suitable material to protect it against erosion. Use riprap or other suitable material on areas where inflow into the pond is concentrated.

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