Ice lifting (or “ice-jacking”) causes significant damage to Wisconsin piers when freezing water expands and adheres to pilings, pulling them from the lakebed as water levels fluctuate. This often destroys docks and boat lifts, particularly on larger lakes necessitating removal, de-icers, or specialized, heavy-duty structures to prevent damage.
Ice jacking occurs when the water rises to a higher level, freezes, and then recedes, leaving a layer of ice along the high-water mark. As the water settles, it freezes again, leaving another layer of ice. As the water rises again, it breaks the second level of ice and pushes it into the first.
The process is similar to jacking up a car to change a tire, hence the name, “ice jacking.” If ice jacking is allowed to persist, pressure will increase, and it can eventually lift your dock enough to pull the pilings out of their foundation, and sometimes even snap them in half.
The Ice Jacking Progression
- Freezing and Gripping: As water temperatures drop, ice forms around a pier leg or piling, locking it firmly.
- Water Level Change: The water level rises due to wind or lake ice expansion forcing water up through cracks. The ice sheet rises with it, pulling the pier leg up.
- Refreezing: As the water level recedes or the ice settles, the ice freezes at a new position around the piling.
- Repetition: This cycle repeats throughout the winter, gradually “jacking” the post out of the lake bed.
Common Causes and Effects
- Water Level Fluctuations: Tides are a common cause of lifting on the coast. In the Great Lakes region, wind and rapid weather changes or manual water regulation (dams) can cause similar fluctuations.
- Ice Expansion: When water turns to ice, it expands by approximately 9-10%. This puts massive pressure on the shore, sometimes called an “ice shove” or “ice ridge” formation, which can damage shorelines and attached structures.
- Damage: Pier legs can be lifted out of their foundations, resulting in crooked, unstable, or destroyed docks.
Prevention
The most effective way to prevent ice jacking is to keep an ice-free zone around the pilings, often achieved by:
- Installing De-icers or Bubblers: Using agitators or air blowers to bring warmer, deeper water to the surface, preventing thick ice from forming around the pilings.
- Removal: Removing floating or temporary dock sections for the winter.
- Using Sleeves or wrap: Placing pile sleeves or wrap over the pilings to reduce the grip of the ice.
Dock Protection Solutions
De-icer
A dock de-icer (Ice Eater) is a great solution, which works as an agitator by circulating the water toward the surface. The device is submerged underwater, where it creates a thrust of water toward the surface. This creates a vertical current effect, which keeps the water moving outward to open up large holes in the ice.
A dock de-icer can also be angled closer to horizontal to create a longer but narrower opening.
Dock Bubblers
Bubblers work by releasing small air bubbles through an underwater hose. The hose has small perforations and is powered by an air compressor. Bubblers can be beneficial if the water near your dock is shallow as they don’t stir up as much sediment as agitators can in shallow water.
Removal
The safest method for preventing ice damage is to completely remove three season and floating pier sections from the water and store them on dry land. Store them far enough away from the shore to protect from ice shoves. This eliminates the risk of ice damage altogether.
Protective Sleeves or Wrap
Placing HDPE (high-density polyethylene) sleeves or specialty wraps on pilings prevent ice jacking by reducing friction, allowing ice to slide along the pile rather than lifting it as water levels shift. These jackets, which can be installed before or after installation, often feature smooth surfaces to prevent ice adhesion.
Using these preventive methods help maintain the structural integrity of the pile, preventing the need to replace or re-drive pilings that have been lifted by ice.
Pier & Waterfront Solutions LLC can help protect your dock from ice damage. Call us today with questions about de-icers, bubblers, or any needed repairs.
Pier & Waterfront Solutions 920-493-4404
