Rum Cove Marina first contacted Seawall Repair Network® contractors Stable Soils around 2017, experiencing severe soil erosion behind their 1,250-foot seawall. The primary issue was water concentration from the parking lot creating a “pressure washer” effect that was washing away soil behind the seawall. This erosion threatened the stability of boat slip pedestals and the marina’s infrastructure.
Initial Assessment
The seawall showed no significant lean, but the soil loss was critical. The marina’s pedestals were falling over, and the concentrated water flow was causing extensive washout. The site required immediate stabilization to prevent further damage and prepare for new infrastructure installation.
Proposed Solution
AP Lift 475 was recommended to fill the voids underneath the walkway due to its high compressive strength. To prevent further erosion from the seawall, SW-RP-1 was utilized to keep the soil from washing away.
Procedures
1. Void Filling:
- Establish a grid pattern for injection points (typically 3 feet apart) underneath the walkway.
- Inject AP-475 two-part polyurethane at a controlled volume to fill void.
- Use dial indicators to ensure that there is no unwanted movement of the walkway or seawall.
2. Single-Component Injection:
- Positioning injection points 12 inches behind the seawall and 12 inches below the mud line (5.5 feet below the cap) every 6 feet.
- Install 1/2-inch plastic jet filters between injection points along the seawall.
- Inject one gallon per vertical foot at every injection point.
- Monitoring for indicators of success such as air bubbles on the water surface and mud displacement near injection sites.
Results
Stable Soils completed the project in September 2020. Since implementation, no further issues have been reported with the seawall. The marina owners were satisfied and subsequently contracted additional sectional seawall repairs.