Solution & Implementation
Furmanite’s extensive experience in concrete repair and technical engineering services, including leak and valve management, was the winning factor in Lakeside Jefferson’s selection of the contractor. Ultimately, Furmanite’s engineering solutions were successful in all phases of repair. Furmanite’s flexibility and trained technicians assessed and changed the job scope as needed to ensure a cost effective, timely and complete restructuring of dam.
Furmanite’s highly trained team led by Todd Murphy, Project Manager, engineered solutions for each stage of the project, including repairing both the downstream and upstream wall; filling the void in the dam; repairing the top cap and repairing numerous leaks and valves. Multiple services were incorporated to create the solution including Concrete Restoration and Specialty Coatings, Valve Repair and Motor Operated Valve Installation.
Downstream Wall Repair
The first step for Furmanite’s expert technicians was to prep the damaged old concrete as a result of continuous freezing and thawing due to water intrusion and hurricane damage. The concrete also had vegetation growing in the voids and cracks that further weakened the structure. After removing the vegetation, Furmanite’s technicians jack hammered and used water blasting to clean the surface. Furmanite proceeded to mix and patch areas with Tamms™ and Sika™ products. The next process involved strengthening the structure of large areas along the dam structure.
Upstream Wall Repair
Another challenge was creating a repair solution for damage caused by implosion to the entire middle section of the upstream wall. Furmanite technicians realized that to perform repairs they would have to remove existing debris, which included concrete, mud, rocks, tree limbs and stumps. This posed numerous problems because a rainstorm of significant force could cause a catastrophic failure of the exposed structure. Furmanite then had to excavate small areas at a time (8′ to 12′ depth by 10′ long), completely prep and tie the existing rock structure together with Tamms Red Line. After this process, the technicians formed the structure with rebar and poured an encasement with Tamms Green Line. After the proper cure time, technicians added more rebar line across the area with Sikadur 33 epoxy paste. A void was then poured with Sakcrete 5000 PSI. The process was repeated across the entire area of the structure, approximately 8′ to 12′ feet in depth by 135 feet long.
Void Fill of Dam Structure
Furmanite’s experts then drilled and installed injection piping on the downstream wall of the structure. The process was completed in a grid pattern to measure depth of void at each location to ensure a bottom-to-top fill of void areas. Furmanite also numbered the grid to track the amount of product injected at each grid point. They utilized a polymer modified Sika 212 Grout product to fill these voids and stabilize the structure of the dam.
Repair Top Cap
Furmanite then prepared, formed and poured a section across the top cap, approximately 130 feet long by 11 feet wide.
Replacement of Sluice Gate Valve installed in 1960s
The next step involved removing the existing cast iron gate, stem and valve body. Complete prep of the surface area involved water blasting and spall repair with Sikatop 123 before the new valve installation. To strengthen the valve pedestal, Furmanite technicians jack hammered the old concrete, installed rebar, formed and poured two inches of Chockfast™ Red Epoxy. After cure time, Furmanite drilled and anchored the stainless steel valve body in place, installed the SS gate, stem and motor operator. Furmanite also prepared the top cap of the dam for wiring to operate the valve from a remote position.
Water Leak Stoppage – Urethane Injection
After filling the lake, Furmanite’s leak sealing experts identified the multiple leaks, drilled holes in a V pattern at regular intervals along the length of the crack and installed Furmanite Injectors. Then using a high-pressure pump, they injected urethane into the structure creating a molding bonded throughout the length and depth of the crack to stop the water flow. As a result, the final cure of urethane is flexible enough to move with the structure.
Lake Wall and Future Pump Station
The next challenge posed to Furmanite’s technicians was to extend and reconstruct a bank retaining wall. The solution included forming and pouring Tamms Greenline polymer modified concrete. Furmanite also added a screen-box to the sluice gate valve intake tunnel built with Sakcrete 5000 PSI. They also added a concrete vault at the retaining wall to hold a butterfly valve and connected piping for the future pump station.