Remediation – Dredging & Leaks
Most everything associated with a drought seems negative, and that certainly is the case for most facets of pond management. However, there are a few opportunities that a drought offers that regular weather patterns and rainfall can make difficult and expensive.
The first and seemingly most popular opportunity among Alabamians is to remediate the pond from a structural aspect. Over time, most ponds experience siltation, that is the margins and basins begin to fill-in and shallow as surface water runoff brings with it topsoil and sediments that ultimately settle out to the pond bottom. As ponds age and sediments accumulate the overall decrease in depth brings along several issues. Besides the obvious loss of water volume, aquatic weeds can also be a significant issue as shallow, silty, waters provide an ideal habitat for excessive weed growth. This growth can impact livestock watering, fish production and balance, irrigation, aesthetics, and so on. As drought is prolonged, water levels recede and shorelines soils dry, offering opportunity to dredge, or remove this excess, unwanted silt and sediment. However, it is not as simple as just digging away with a dozer or track hoe, careful planning must first take place as many ponds could end up ruined at this time.
Understand that if the compaction layer of a pond is disturbed a leak may develop. Many ponds hold water because of careful and calculated clay compaction at first construction, with some sites even having clays hauled in order to provide proper compaction. If the compacted layer of pond bottom is disturbed and not sufficiently compacted after dredging, the risk of a leak is high. Also, consider what you will do with the ‘spoil’ or material that is removed, all of that sediment has to go somewhere. Often times there may be a location on the property, but, if not, with a few calls to area farmers or landscapers it may not be difficult to find a taker. If placed on-site, remember to select a location downstream or outside of the watershed of the pond, after-all you don’t want rains carrying all of that material back into the pond. Lastly, once rain is on the forecast it is a good idea to seed or cover crop the spoil area to reduce erosion.
The next question of such an undertaking is cost. Generally, such a job is charged by the hour. Depending on size and type of machine, you can expect hourly rates in the range of $100-$200. Costs can vary widely based on location, soil moisture, and the need to haul and/or spread the spoil.
Another opportunity during a time of drought is the ability to repair a leaking pond. Again, exposed pond bottoms provide opportunity to properly compact soils or investigate that nagging leak. Perhaps a bedrock seam or sink has been exposed, those holes or rusted areas in the standpipe can now be addressed, or that area of the pond that wasn’t able to be properly compacted now has the chance. Ponds can leaks come develop in a headspinning amount of ways, but a drought may provide the chance to pinpoint and fix the problem in a more timely and economical way than with a pond at full pool.
Norm Haley, Forestry, Wildlife, and Natural Resource Management Regional Agent