CASE STUDYMUNICIPAL CONCRETE BULKHEAD REPAIR

SOLUTION

Coastal Foundation Solutions was contacted by Chester Young of Hans Wilson and Associates, a marine consulting/engineering firm in Fort Myers. The engineer was searching for the design and installation of a permanent solution to the undermining of the existing retaining wall. The primary concerns of the engineering team were the design life of the foam structure in a marine environment and the capacity to seal approximately two-hundred feet of upland retaining wall. The wall required an additional two to three foot of foam to be injected beneath the existing retaining wall. This translates to foam being injected 8 to 10 feet beneath the existing grade.

Since the original retaining wall construction design had only eight (8) foot vinyl panels, the Deep Foam Injection process would require multiple injection ports to seal the bottom. The injection process was selected to avoid clashing with the existing structures and mature landscaping. Access to the project site as well as equipment mobilization and material deliveries were severely constrained due to project location.

DEEP FOAM INJECTION INSTALLATION

Before the installation of production ports, it was mutually agreed that Coastal Foundation Solutions would run a trial process to insure the prescribed material would proceed as designed. We injected six (6) locations and did not encounter any sub-surface soil conditions that we could not penetrate with our equipment.

A Quality Control person oversaw the foam injection testing and installation and provided correspondence to the City of Fort Myers. The city accepted our Deep Foam Injection proposal and engaged us to proceed forward with the project. Injection monitoring was performed by Hans Wilson and Associates of Fort Myers, Florida.

INJECTION PROCESS

• The deep foam injection procedure, is an environmentally nontoxic, high density, hydro-insensitive polymer which is injected into the sub-surface soil. Once injected, it expands into a foam and fills in all of the air and water crevices that were in the subgrade. We were injecting foam 8 to 10 foot into lower soil levels.

The deep injection process utilizes exceptional polyurethane foams that are injected into areas that have been exposed to deep soil issues such as soil and water erosion. This solution causes less downtime, is less invasive and helps preclude collateral property damage during the process.
Coastal Foundation Solutions determines locations for the series of injection holes ( approximately 2 ft. on center) based on engineers plans. The 5/8-inch holes are then drilled through the existing soils into required depths. After drilling of the 5/8-inch holes, a ½” steel pipe/probe is placed into the ground, then high-density polyurethane foam is injected into the soil through the probes. The foam expands and hardens, creating the necessary filling forces.

The pumping unit provides a consistent rate of injection and the volume of foam rise can be controlled. After the nozzle is extracted from the hole, excess polyurethane material is cleared from the area. The foam material achieves 90% of its highest compressive strength after 15 minutes.

PRODUCTS

• 360 – ½’ Steel Pipes
• Four thousand seventy-three (4,073) pounds of Alchemy-Specte AP 700 High Density Polyurethane Foam.
• Provide 36 c/y of clean sand to fill existing voids and compact in lifts
• Install 800 sq. foot of St. Augustine Sod

PROJECT SUMMARY

• Engineer: Hans Wilson and Associates
• Consulting Structural Foam Engineer: Alchemy-Specte
• Contractor: Coastal Foundation Solutions

KEY ADVANTAGES

• Restrained Access
• No Disruption of Landscaping or Utilities
• Direct Proof Testing and Loading
• Extend Probes Proficient Soil Zone
• Virtually no Pulsations/ Pounding Sounds