Great Lakes Rising
Great Lakes water levels have risen over 6’ since 2013 covering most existing beaches left after the last high-water event in 1986. The Great Lakes are projected to rise another 19 inches in 2020 putting most shoreline property and many structures at risk.
Traditional remedies to control bluff toe erosion include rock revetments, sea walls, and sandbags. Unfortunately, no erosion control structures are guaranteed due to the unpredictability of mother nature although most failures are due to inadequate design and improper installation. Most erosion control structures typically cost less to install with adequate landside access.
are an excellent solution when properly designed and installed at a cost usually exceeding $2,500 per running foot if correctly installed, obviously substandard installations with smaller amounts of smaller rocks will be much less expensive and often disappear in one good storm, less is defiantly not the more you will need. Typically, the beach is excavated as low as possible below water level, a geo textile is installed to keep the rock separated from the sand with a 24” layer of small stone to protect the geo textile from puncture. Progressively larger rocks are added with a front and top layer of large armor rocks to break up and dissipate wave energy. Proper installation and enough stone are critical. Some negatives that drastically reduce rock revetment service periods include:
- Improper design without enough rock and improper installation elevations
- No geotextile or mattress bed allowing rocks to rapidly sink with wave action.
- Unknow or short quantities of rock installed (demand all weigh slips from drivers)
- Rocks move, sink, and disappear requiring multi year replenishment.
- If shoring up under foundations ground water soil migration causes erosion and settling
Also rock revetments;
- Make lake access for humans and animals difficult and dangerous.
- Are very difficult and expensive to remove if lake levels go down.
- Are not conducive to stairs, decks, or boats.
- Require major logistics and cost to transport and install on site
- Cause significant erosion and habitat damage with lakeside traverse
when property designed and installed are a great solution as proved by the local piers. Cost are typically higher then rock revetments and vary with construction access. Typical failures are caused by;
- Sheet piling not heavy enough allowing sheets to buckle and separate, especially from ice
- Inadequate sheet length allowing scour (the underwater transport of sand/bottom caused by water currents resulting from wave energy dissipation) to undermine bottom sheet holdback support. (rough rule, 1/3 above water bottom, 2/3 below)
- Inadequate tiebacks/anchors allow wall to fold lakeward bulge/fail
- Dissipating downward wave energy creates a drop off in front of wall.
- The change in water flow often enhances erosion on adjacent properties and sidewall extensions often need to be added creating a peninsula effect
- No geo textile behind wall allowing backfill to erode through
are a great temporary solution for holding back flood water and many have been installed on Lake Michigan, big ones, small ones, filled with sand and some filled with cement. Lack of consistent installation materiel’s and methods make judging they’re relative effectiveness very difficult.
- Installed only by reputable contractors with insurance proofs on file
- Cost effective compared to other options
- Fast installation (typically less than a week depending on weather)
- Recyclable and nonpolluting
- Robust construction exceeding ACI standards for reinforced concrete
- 120-ton mass to counteract wave forces
- Pile retention eliminates slope migration if needed
- Galvanized and coated connection hardware
- Corrugated surface causes turbulence to dissipate wave energy
- Corrugated surface retains suspended soils and allows for future re-vegetation
- Self-adjust for front and side scour
- Removable, can be stored and reused or sold
- Expandable to adjoining properties
- Can be installed in all weather with reasonable surf
- Can be installed from land side with suitable nearby crane access
- Eliminates wind scour from covered surfaces
- Uses local materials and local materiel suppliers
- Maintains bluff face regardless of water level
- Allows limited boat access
- Gradual slope profile has less adverse effect on adjoining properties
- Limits sedimentation of near shore and off shore aquatic breeding nursery’s
- Enhances shallow water breeding nursery depending on lake levels
- Allows reasonable shoreline access to humans and wildlife
- Allows stairway securing and installation
- Allows deck or boat house installation
- Allows installation of overtopping barriers if needed
- Can be installed without removing existing tree lines or vegetated slopes
- Allows the establishment of optimum 2 to 1 slope for re-vegetation
- No protrusions and pile caps allow traverse of rubber tired or tracked equipment
- Reduces lake erosion filling which contributes to high water level