Soil stabilization / Erosion control – Polyurethane Resin Injection

Service Type: Soil stabilization / Erosion control – Polyurethane Resin Injection
Client: Residential Customer
Location: Traverse City, Michigan
Structure Type: Residential seawall 100′ LF

Problem: High wave activity had caused severe soil erosion behind the concrete seawall with material outflow below the wall at the toe of the wall back into the lake. The client hired a seawall remediation company out to reinforce the toe with rip rap, fill the soil voids and install a splash bed for saturation mitigation but still the soil continued to erode and sinkholes quickly formed 6 months later.

Solution: A single component hydrophobic polyurethane resin was used to inject below the surface to a depth of 6+ feet the entire length of seawall as shown (in diagrams) in two locations. This will find and fill the erosion pathways while strengthening and binding the soils to keep from over saturating and eroding.

Challenges: The customer was in a hurry to get the work completed and wanted it done asap. The earliest the project could be scheduled was mid January but snow and low temperatures were potential problems. The ambient and surface temperature were constantly monitored by the customer and relay back to make sure the ambient was above freezing and soil surface temps were at least 40+ degrees. At the time of work it had just snowed but the ambient temps were 36 degrees and soil surface temps were 41 degrees. The material and 5% catalyst was heated in the trailer on the way and on site in a tent to 80+ degrees to account for heat loss when injecting into the colder soil. The reaction times were exactly as expected. The other challenge was to inject below the splash bed but not clog the water mitigation pipe buried below the rocks in the splash bed, for that the injection probe was marked and flow timed per the expansion rated we were seeing and held 18″ below the surface as to not flow material into the pipe openings. Pipe was also periodically inspected with a bore camera during injection and upon completion.

Results: Project was completed in 1.5 days time just before heavy snow and subprime temperatures rolled in. Just over 100 gallons plus 5% activating catalyst was used. All materials used are NSF/ANSI standard 61.5 safe for contact with potable water. The predetermined injection grid was perfect for material overlap in the soft sandy soil. The heated material temps achieved a proper and predictable flow that was so consistent it could be timed for expansion expectations. All in all despite the unfavorable weather the project was straightforward and successful along with a happy customer.