Ice Blockage of Intake Trash Racks Stops Utilities Cold

The U.S. Army Corps of Engineers Cold Regions Research and Engineering Laboratory (CRREL) has published a short technical report that discusses a major problem for any facility that operates a water intake located in area that can experience cold weather: Frazil Ice Blockage of Intake Trash Racks. Water from lakes and rivers is vital for power plants, municipal water supplies, fish hatcheries, and industrial processes. Water intakes generally have trash racks, which are screens that keep natural and man-made debris from entering the facility. One of the most difficult problems these facilities face is the accumulation of frazil ice on their intake trash racks. Frazil ice crystals form in turbulent, super-cooled water that can be generated during cold winters such as we are experiencing this year. Frazil ice particles can accumulate on an intake trash rack and completely block it, rapidly and unexpectedly shutting down the flow of water. The CRREL report, which is written for intake operators and designers, describes the physical processes involved, offers guidelines for operating under frazil ice conditions, and describes the solutions that are available.

The report can be viewed or downloaded at http://www.crrel.usace.army.mil/techpub/CRREL_Reports/reports/CRTD91_01.pdf.

Edited by Kate Goff