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LAKE MICHIGAN SHORELINE EROSION: Protecting your assets

09.27.19   Robert C. Rabeler, PE | More by this Author, Jeffery M. Krusinga, PE, GE | More by this Author

LAKE MICHIGAN SHORELINE EROSION: Protecting your assets

The water level in Lake Michigan is near an all-time high right now. High water levels have caused accelerated erosion to the shoreline, resulting in rapid loss of real estate. Unfortunately, this loss of ground has resulted in failure of shoreline structures such as stairways and decks, and even total loss of houses.

Protecting the shoreline and mitigating rapid loss of shoreline real estate is possible, but requires careful engineering evaluation and design. An Owner that is looking to protect their shoreline should retain a Professional Engineer with knowledge and experience with Lake Michigan shoreline erosion protection.

When designing protective structures along the shoreline, some or all of the following tasks could be part of the project scope:

  1. Evaluate the soil and groundwater conditions by performing geotechnical borings. Determine whether groundwater seepage along the bluff may be contributing to bluff instability. Determine if the beach sand is underlain by a clay shelf close to the surface.
  2. Determine the design water depth at the site. The design water depth is a function of predicted lake levels (including long-term rise due to climate change), storm surge, wave setup, and scour. The design water depth is important because this depth controls the height of a wave that can break onto the shore. The deeper the design water depth, the larger the waves. Also, evaluate near shore bathymetry at the project site.
  3. Evaluate the geometry of the site. That is, the steepness of the bluff or slope, the location of existing structures, and existing property boundaries.
  4. Determine if neighbors will participate in funding shoreline protection to reduce risks and costs.
  5. Evaluate access for construction equipment, either from land or from water using a barge.
  6. Evaluate structural options for shoreline protection such as use of riprap revetment, sheeting, or retaining walls. Evaluate whether implementation of “softer” solutions (in combination with structural options) could be of value, such as sand replenishment on the beach or drainage measures to collect and control groundwater seepage along bluffs.
  7. Evaluate aesthetics for shoreline protection options, and whether potential options may impact uses of the beach area, including beach access.
  8. Work with governmental agencies regarding permitting issues (some options may not be allowed).
  9. Estimate costs for shoreline protection options and compare those costs with the risks for erosion/loss of ground and loss of investment in land and structures.
  10. Prepare engineering documents showing the details and specifications associated with the selected shoreline protection system.
  11. Obtain required governmental permits.
  12. Obtain bids from reputable and experienced contractors familiar with Lake Michigan shoreline protection projects.
  13. Monitor construction to verify the shoreline protection system is properly built according to plan.

While these tasks are typical, other activities may be required once the details of the site and uses of the property are known.

For more information regarding Lake Michigan shoreline protection, contact Bob Rabeler, PE or Jeff Krusinga, PE, GE.



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