Bluff motion has been a problem for property owners for more than a century, originating in glacial times.
Roughly 13,000 Years Ago Glacial activity created the unstable soil and sand layers visible today along much of Lake Michigan. About 50 feet above lake water level are sand layers left from glacial-era beaches. Groundwater flows through sand layers toward the lake, causing the mostly clay bluffs to slide over sand layers. As water builds up, the added weight and water cause the bluff to slide further downward and collapse.
Sand layers left from glacial activity are still visible in bluffs along Lake Michigan shores.
1927 In Whitefish Bay, Wisconsin, post-glacial action caused 500 feet of Lake Michigan bluff – along with the mansions on it – to move lakeward at a staggering average rate of four inches per day.
1936 A tunnel was dug by hand 50 feet below ground surface and 400 feet behind the Whitefish Bay bluff crest to intercept groundwater flowing toward the bluff. That bluff has been stable since 1936.
1936 civil engineering study
1990s More practical solutions emerged. Special groundwater drains were used in highway embankments to prevent failures. A federal government grant confirms the success of these drains.
2000 - 2002 Gillen Co. devises a bluff drain solution to stabilize bluffside properties and begins successfully using the system to prevent further collapses. Geotextile-coated wick drains can now be installed from a bluff top using horizontal directional drilling (HDD) methods patented by Gillen Co.
U.S. Patent No. 6,948,886.
2007 Bluff failure is still a problem along Lake Michigan, endangering the investments and safety of private and public property owners. Today, Gillen is proud to offer this exciting, effective solution.
