The City of Alpena (City), Michigan contacted DN Tanks Concrete Tank Services (CTS) for options to address leakage from and groundwater infiltration into one of their reinforced concrete tanks at the water treatment plant. The 0.5 MG rectangular concrete tank was fully buried and divided into two separate chambers. Although DN Tanks was not involved in the original design or construction, many municipalities such as the City, often call on DN Tanks for their repair recommendation. DN Tanks CTS was contracted to provide inspection services to evaluate suspected leakage from the tank and provide recommendations for rehabilitation.
DN Tanks worked closely with the City’s Engineering Department to develop a plan for making the required repairs. The scope of work included waterproofing the interior walls, floor, and exterior roof of the tank.
While performing the interior waterproofing on the first chamber, DN Tanks observed additional deterioration inside of the tank due to ground water and water from the adjacent chamber seeping in through the walls and floor. DN Tanks was able to work with the City to revise the scope of work and use alternate materials in order to still complete the project on schedule and under budget.
DN Tanks was later contracted to return to the site to complete the waterproofing on the second conventionally reinforced concrete water chamber. While cleaning the chamber and preparing to apply the waterproofing coating, DN Tanks also observed structural deficiencies with the concrete columns inside of the tank. DN Tanks Engineering Department performed a review of the existing tank and designed a supplemental support system for the underside of the roof to provide additional support and extend the service life of the tank. In addition, new vents and roof access hatches were designed and installed in order to meet the current codes and standards.
DN Tanks’ expertise in evaluating deficiencies and issues with leakage in conventionally reinforced concrete structures as well as the ability to provide value engineering solutions allowed the City of Alpena, Michigan to gain many more years of service out of their newly rehabilitated tank.