Chapter 12: Other Pond Problems
Marley D. Beem and Jeff J. Blaser
Previous chapters have covered issues in fisheries management and vegetation control, but a variety of issues that are partially or entirely beyond the boundaries of fisheries biology face the manager of a small impoundment. These issues overlap into such areas as civil engineering, public health, safety and human relations. The discussion of such topics here is not intended to replace the involvement of professionals in these areas, but rather to equip the reader to effectively interact with appropriate authorities. The small impoundment manager is also likely to be surprised by some highly infrequent situations or problems that unfold so gradually as to be imperceptible without proper awareness, monitoring, and understanding. If the recommendations presented herein seem burdensome, consider that many of the failures observed by the authors could have been prevented if due diligence had been pursued.
Avoidance of pond leaks depends on good site selection and the use of proper dam construction techniques. Local Natural Resources Conservation Service (NRCS) or other knowledgeable professionals should determine if there is a sufficient water source present to naturally fill and maintain the pond and if the water holding capacity of soils present at the site is suitable. A soil profile should be conducted to a depth several feet below the anticipated depth of excavation. These steps will help determine if the pond site is appropriate.
During construction, topsoil on the future dam site first must be removed and stockpiled nearby to facilitate topdressing the completed dam (Chapter 2). Soil used to construct the dam must have adequate moisture content to ensure proper compaction as the successive layers are laid for the dam. A well-compacted clay core trench tied into an existing clay substrate will also work to prevent excessive leakage through the dam. Anti-seep collars are needed on all pipes through the dam. In addition, soil around the drainpipe must be thoroughly compacted, in successive layers, by manual tamping. These steps are necessary to prevent leaks due to water seeping under the dam, through the dam or along the drainpipe (see Chapter 2). A minor amount of seepage through earthen dams is normal (FEMA 2005a, 2005b).