Frazil Ice / Frazzle Ice

Frazil ice are small, needle-like structures or thin, flat, circular plates of ice suspended in water.  In rivers and lakes it is formed when sub-freezing air cools the surface of the water to slightly below the freezing temperature.  This condition is called supercooling as ice does not automatically form.  A supercooling of just a tenth of a degree Celsius is sufficient.  If the water is turbulent, the supercooled water mixes into a thicker layer.  Once supercooling has occured, tiny ice crystals begin to form which are suspended in the supercooled layer.  These crystals are called frazil ice.  Turbulence also causes the multiplication of ice crystals, which float slowly upward, accumulate, and become the surface slush layer needed for pancake ice.

Basically, the colder (below 32 degrees F) and more turbulent the water, the faster that frazil ice will form, so long as there is not a "substantial ice cover".  What all this means to users of raw water is that trash racks and screens get plugged with frazil ice.  This can cause a complete blockage of water intakes for cities and municipaIities. It can also cause the collapse of trash racks or screens.  Loss of water is not just inconvenient, it's a hazard to public safety.  Unfortunately, there are not many solutions to the problem.  One solution is to introduce a diffused flow of heated water into the intake system on the upstream side of the trash rack. Another remedy is to electrically heat the metal trash racks or screens.  Both of these solutions while proven to be somewhat successful, are very expensive to purchase and even more expensive to install.  Then there is the burden of electric and yearly maintenance costs.

UCI has an agreement with a manufacturer of trash racks and screens which are specifically designed to eliminate the frazil ice problem while providing several other benefits.  These racks have been designed and installed for both municipal and industrial clients in the Northern U.S. and Canada, in addition to clients in Scandinavia.  These installations have met with great success and client references with contact information are available.  You will be surprised at the cost savings that this system will offer over its competitors, and there are no maintenance or operating expenses associated with this system.