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NRD Dam Rehab Projects

The Lower Big Blue Natural Resources District has considered and utilized various methods and products for combating the problems that often accompany aging dams over the years.  Very often, the culprit is oxidation, particularly on structures which employ a corrugated metal pipe (CMP) for the principal spillway.  Generally, over the life of a dam, a CMP will begin to develop rust on the bottom side of the tube.  Given enough time, pin holes may develop which ultimately turn into larger holes, and invariably, voids can begin to form under the principal spillway causing undercutting and potentially failure of the dam to function properly. 


The past couple years, the NRD has been in the process of installing Snap-TiteTM High-Density Polyethylene (HDPE) pipe in many of its structures.  As the name implies, the pipe snap together around a gasket, and can be fused to a new riser once inserted into the existing tube.  Ventilation and grout pipe are installed alongside the new tube for efficiently injecting grout into the annular space which remains.  This creates a solid bond between old CMP and new HDPE, extending the life of the structure well into the future.  The HDPE is able to be of smaller diameter due to the difference in hydrology between smooth-walled pipe (the HDPE) and the CMP, or existing pipe.  The process usually takes about a week and saves quite a bit of time and money.


 



 



 



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