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1230 Peachtree Street NE | Promenade Building | Suite 1100Atlanta, GA 30309 | 855.526.4413 | utilityservice.com

Case Study Pressure Cleaning, Coating, & Repair in Avon, Connecticut

© Utility Service Group, 2014. All Rights Reserved.

Avon, Connecticut was faced with a challenge when their concrete tanks exhibited signs of wear and tear. Their concern focused on the City’s two concrete water tanks located at Hunters Run and Woodmont. The City selected Utility Service Group to rehabilitate the damaged tanks and place them under a 10-year asset warranty.

Utility Service Group maintenance personnel inspected the tanks, and they pinpointed multiple issues and promptly alerted the City of Avon to the situation. And in July of 2014, the USG team proceeded to restore decades of corrosion and ensure the safety and cleanliness of Avon drinking water.

Utility Service Group’s response team first began with the Woodmont water tank, and is slated for completion in December of 2014. After completion of the Woodmont water tank, Utility Service Group will move forward on the Hunter water tank shortly thereafter into 2015.

Overview




The Problem

The Solution

The Woodmont Tank - 30 years old

During the inspection, USG experts noted that the exterior coatings had reached the end of their life cycle and was no longer protecting the concrete. Hairline cracks had been previously routed out on the exterior roof and were exposed to the environment. Those aforementioned cracks having gone through several freeze/ thaw cycles and appeared to have caused the cracks to deepen. Most of the exterior shell walls were below grade and could not be evaluated, but what was exposed above grade was showing some significant cracks in a few areas.

Concerning the inside of the tank, the interior concrete had never been coated. There was frequent cracking on all interior concrete surfaces and efflorescence was visible on some of the cracks in walls and roof. Some of the larger cracks had been repaired in the past. Spalling had occurred in some of the chambers just at the wall/ roof line, exposing rebar in some areas. All walls were sounded with a hammer to reveal some hollow sounds in chamber three. In addition to the walls, all floors were also sounded with no hollow sounds.

To address this deterioration, all roof exterior surfaces shall be cleaned using an 8,000-10,000 psi pressure washer to remove any old coating or sealants. Walls shall be cleaned using a 3500 psi pressure washer to remove any debris and efflorescence. Repair mortar shall be used to fill spalling areas ¼” or greater in depth. All roof cracks shall be routed to ¼” depth and ¼” width and filled with a 100% epoxy and aggregate mixture. Wall cracks shall be routed and filled with polyurethane caulk. The roof exterior shall receive a full prime coat of high build epoxy at 6-8mils dft, and that roof shall receive a full intermediate coat of high millage polyurethane at 50-60 mils dft. The finish coat shall be a polyester polyurethane coat at 2.5-3.0 mils dft. A non-skid surface on said roof shall be achieved using an aggregate that has been broadcasted into the finish coat during application. Walls down to grade shall receive two full coats of latex at 6-8mils dft.




The Solution

Inside the tank, all concrete surfaces including walls, floor and ceiling shall be cleaned using a 3,500 psi pressure washer to remove any bio-film or sedimentation from the interior surfaces. All interior surfaces shall be abrasive-blasted, leaving a profile that matches the ICRI CSP #5 Comparator. All exposed rebar shall be abrasive-blasted to a SSPC-10 near white and coated with a zinc primer. After clearing these deposits from the tank, the next step will be to seal cracks and apply coating. All spalling areas ¼” in depth or greater shall be filled with a repair mortar. Cracks on walls, floor and ceiling shall be evaluated to determine which cracks are large enough to receive a grout injection. Once the USG team has smoothed over all surface degradations, surfaces shall receive a cementitious parge coat at a minimum 1/16” sprayed and back trowel to fill any irregularities on concrete surfaces. The walls, floor and roof of the interior shall receive a full coat of high build NSF-approved epoxy at 3.0-5.0 mils dft. The walls and floor shall be top coated using a high millage NSF-approved polyurethane at 50-65 mils dft. A non-skid surface on the floor shall be achieved using an aggregate that has been broadcasted into the finish coat during application.

The completion of the Hunters Run tank rehabilitation end in December 2014.




The Problem

The Solution

The Hunters Run Tank - 30 years old

The tank at Hunters Run will be rehabilitated subsequent to Woodmont. Here the exterior concrete was found to have no protective coating, and the exterior exhibited spalling areas mainly on roof edges. Exterior shell walls were mostly below grade, hence the foundation was not accessible for inspection. The roof and shell wall had hairline cracks

Frequent hairline cracks were found throughout the interior. Gunite was found to have delaminated in several areas on the walls and floor. Interior roof cracks were also showing some efflorescence.

On the outside of the tank, all roof exterior surfaces shall be cleaned using an 8,000-10,000 psi pressure washer to remove any old coating or sealants. Walls shall be cleaned using a 3,500 psi pressure washer to clear any debris and efflorescence. The USG team will utilize repair mortar to fill spalling areas ¼” or greater in depth. All roof cracks shall be routed to ¼” depth and ¼” width and filled with a 100% epoxy and aggregate mixture. Wall cracks shall be routed and filled with polyurethane caulk. After irregularities in the exterior roof shall receive a full prime coat of high build epoxy at 6-8 mils dft, and the exterior roof shall receive a full intermediate coat of high millage Polyurethane at 50-60 mils dft. The finish coat shall be a polyester polyurethane coat at 2.5-3.0 mils dft. Then, a non-skid surface on roof shall be achieved using an aggregate that has been broadcasted into the finish coat during application. Walls down to grade shall receive two full coats of latex at 6-8 mils dft.

Inside the tank, all concrete surfaces including walls, floor and ceiling shall be cleaned using a 3,500 psi pressure washer to remove any bio-film or sedimentation from interior surfaces. All interior surfaces shall be abrasive blasted leaving a profile that matches the ICRI CSP #5 Comparator. All exposed rebar shall be abrasive blasted to a SSPC-10 near white and coated with a zinc primer. All spalling areas ¼” in depth or greater shall be filled with a repair mortar. Cracks on walls, floor and ceiling shall be evaluated to determine which cracks are large enough to receive a grout injection. After evening surface irregularities, wall surfaces shall receive a cementitious parge coat at a minimum 1/16” sprayed and back trowel to fill any irregularities on concrete surfaces. Interior walls, floor and roof shall receive a full coat of high build NSF-approved epoxy at 3.0-5.0 mils dft. The walls and floor shall be top coated using a high millage NSF-approved polyurethane at 50-65 mils dft. USG will use an aggregate that was broadcasted into the finish coat during application to achieve a non-skid floor.

The rehabilitation of Hunters Run tank is slated to begin in 2015.

To learn more about this leading-edge approach to rehabilitation for your concrete tanks, please contact Jonathan Cato, VP of Tank Services at 478.988.5241 [email protected].

ase study pressure leanin oatin reair in avon onnetiut ... · 1230 peachtree street ne promenade...

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