Seawalls are used to delineate a border between land and water while providing protection from waterside land erosion.

Benefits of Seawalls:

• Provide a consistent permanent land side grade elevation allowing the installation of lawns, patios, decks or other permanent improvements.
• Provide a great anchor to secure watercraft if sufficient depth is present and a great anchor for any docks or other improvements that may be installed facilitating water access.
• Can last for decades if properly installed initially and conditions remain consistent.
• Provide a considerable increase in property value and recreational waterfront enjoyment.
• Stops erosion and eliminates valuable land loss
• Relatively short installation time

Some disadvantages

• Waves of any size tend to discharge they’re energy downward when stopped by a seawall increasing erosion and water depth directly in front of the seawall.
• Depending on the wall top elevation human and animal access is greatly restricted
• Materials and installation is not inexpensive, more so if the wall location is not landward accessible for installation.
• If neighboring properties do not have adjoining structures a corner or landward return may be needed and erosion may accelerate on the adjacent unprotected properties

Types of sea wall materials

• Steel sheet piling, most commonly used, high strength which also simplifies installation, relatively long life if adequate thickness, available on fairly short notice and relatively easy to cut and weld to.
• Plastic/Vinyl, singular advantages of unlimited sheet life span, lower tensile strength making driving more difficult with a higher risk of damage, caps and tiebacks are typically bolted on treated wood with limited life span and must be oversized to hold sheet straight, (see drawing), more easily damaged by any significant ice at lower temperatures.
• Aluminum, low strength, long life span if no electrolysis factors are present, very expensive with longer procurement times, low strength making driving difficult, more to weld or fabricate, is damaged fairly easily
• Wood, typically jetted in double layers, is not recommended for long term applications although is great for low impact inland lakes and for decoration.

The process

• Measure length of desired seawall, determine desired height above the bottom and desired land grade and obtain materials quotes, including sheet piling and profile, tieback anchors and rods, waler and cap materiel. (see drawing) Seawalls are usually priced per foot and a rough rule of thumb for stand alone walls is 2/3 of the sheet should be below the bottom of the waterway. (4’ above bottom equals 12’ sheets which is often reduced with sufficient tiebacks) Cost to install heavier gauge (thickness) sheet piling versus lighter gauges are the same although the projected life span is greatly increased with thicker sheet piling which is important to note in comparing prices. (see sheet piling gauges below) Another construction sheet piling installation practice is “short sheeting” which consist of shorter length sheet piling installed with longer sheets interspersed at intervals, which we believe causes inconsistent loading and risk possible bottom washout due to seawall caused erosion or changing water levels. If you are looking for either the lightest gauge materials or short sheeting we are not the contractor you should choose.
• Determine and verify a site access method and any associated cost.
• Calculate all materials, equipment mobilization and operation, fuel and labor cost and provide client a proposal.
• Typically, if permits are not in place our permit agents will provide all drawings, site surveys, and submissions for the various permits and in Michigan are typically issued within 2 to 6 months after various negotiations with Michigan’s EGLE and USAC, the United States Army Core of Engineers as well as local zoning and soil erosion agencies. For more information on permits please search for Michigan JPA, “joint permit application”, Michigan’s EGLE applications include the required Federal USAC submittals thus the JPA designation.
• Installation times vary with wall and sheet lengths, typically walers, tiebacks, and cap are installed after the sheet is driven, the wall is back-filled, landscaping is typically done by others. Please note wall back fill setting rates will vary and should be taken into consideration when installing any further improvements.

Your Trusted Partner for Shoreline Stability

Contractors Marine is dedicated to delivering exceptional results, ensuring your seawall is constructed with the highest standards of quality and integrity.

Contact us today for a site evaluation and to discuss your seawall construction or repair project in Michigan or the surrounding Great Lakes states! Let us handle the permits and complexities so you can protect and enjoy your waterfront property with confidence.