Repairing Structures: Knowles Saves Wastewater Plant Control Building

East Windsor WPCA Concrete Repairs & Coatings

In January of 2016, Woodard & Curran Inc. contacted management at Knowles Industrial Services Corporation and requested their professional opinion on wastewater concrete repair during a job site inspection at a plant in Northern Connecticut. The intent of this inspection was to identify structural issues and varying types of concrete and steel deterioration in the Control Building at the Water Pollution & Control Authority. Woodard & Curran then authored a structural condition assessment memorandum to the owner with repair suggestions and called upon Knowles Industrial Services to supply a cost estimation and work plan for a concrete repair service. The reinforced concrete floors in the Control Building had severely compromised structural integrity due to contamination and repeated exposure to sodium hypochlorite; an acidic chemical compound commonly used in the wastewater disinfection process.

Dealing with Concrete Contamination Safely and Efficiently

The concrete slabs on the ground floor had been heavily saturated with disinfectants. Much of the contaminant had migrated through spalls and cracks in the slab, reaching down to the underlying structural steel reinforcement and allowing the corrosion process to take place. The corrosion caused the embedded steel to expand and spall the concrete through a process known in the industry as "rust jacking". This process also reduced the overall tensile strength of the reinforcement itself.

The WPCA contracted with Knowles Industrial Services to perform the repair work per specifications laid out by Woodard & Curran. The work items included demolition and replacement of over 400 SF of concrete floors and ceilings, secondary containment modifications/waterproofing/and chemical lining, structural steel surface preparation and coatings in the basement, urethane injection and coatings of leaking cold joints in the sump pit, and surface preparation and painting of the concrete basement walls.

"I often strongly recommend to Owners that they work with Knowles, in my opinion one of the best and most reputable repair contractors in New England... They always get the job done right and at a fair price, and I have found their project management staff and field crews to be an absolute pleasure to work with."  

-Jim Sturgis (Sr. Structural Engineer at Woodard & Curran)

Knowles Senior Foreman Dan Tardif and crew quickly had to overcome some difficult site conditions. The contamination reached a level of severity that required all concrete demolition be performed with strict adherence to respiratory and skin protection programs. The demolition dust was harmful and measures were taken to ensure workers could properly demolish and dispose of the contaminated without being exposed to harmful chemicals. Prolonged sodium hypochlorite contact with skin, eyes, or lungs can lead to irritation, rash, or acidic burns.

Meeting Important Concrete Repair Deadlines

The project schedule was a concern for the owner as they would only permit 7 working weeks to the contractor so that the disinfection season could start as normally scheduled in the Spring months. Knowles had to staff the project with a highly-experienced crew in order to meet the customer’s needs. All East Windsor plant operators and maintenance personnel were extremely knowledgeable and helpful throughout the construction process. The project’s success was highly attributed to the team effort put forth by all parties involved in the project.

Knowles completed all work scopes on schedule and were able to provide some additional repairs to the owner within the same timeline. Woodard & Curran and Knowles Industrial Services once again successfully worked together to provide the customer with high-value repairs at a fair price.

"Due to the great work of Dan Tardif and crew the building was able to be brought back into structural integrity. Dan went above and beyond what I expected. The building is now in better shape than when new... It was a real pleasure working with you and Knowles on this very difficult project and we are very pleased with the result."

-E. Arthur Enderle III (Superintendent at WPCF)