Sealing pond bottoms with muddy water

Seepage losses from constructed wetlands, wildlife refuges, wastewater lago ons, runoff collection ponds, and other engineered surface impoundments of water or aquatic ecosystems in areas with deep groundwater levels can be mi nimized with artificial liners (plastic, compacted earth, etc.) or with nat ural processes like sediment accumulation and microbiological and chemical processes. Sediment accumulation can be increased by deliberately adding so il slurries or muddy (turbid) water. When these are applied to the water su rface, settling of the particles to the bottom then creates a graded sedime nt layer with the coarsest particles on the bottom and the finest particles on top. Column studies in the laboratory showed that, for a given amount o f soil added, such a graded layer gives more seepage control than a compact ed earth liner. Also, split slurry applications to create a layered lining gave more seepage control than when the same total amount of soil was given in one single slurry application. Subsequent addition of sodium carbonate to the water reduced seepage even more, giving a total seepage reduction in the columns from 1000 to 0.2 cm/day. The study also indicates the importan ce of avoiding turbid inflows into infiltration basins for,groundwater rech arge, as well as soil erosion within the basins themselves, if infiltration rates need to be maximized. Published by Elsevier Science B.V.