HOW TO
»
BY GREGORY MAUGERI
Tanks For Everything: Waterproofing Our Concrete Infrastructure measurable and meaning metric greater than 25%. Contractors can use different Gregory Maugeri / Bill Della Sorte methods depending on what is discovered water for a 24-hour period. In large and how much degradation. Reinforcetanks, this can be negligible and typiment should be cleaned via brushing, cally within the evaporative levels. For grinding and blasting and then treated a 750,000-gallon tank, 0.1% would be with the inhibition agent. The areas were 750 gallons of allowable leakage. finished with a crystalline mortar out to In Vergennes’ case, the square tank flush with Kryton International’s Bariwas experiencing leaks from cracking, cote or Krystol Repair Grout crystalline spalling from freeze-thaw cycling, and cementitious mortar or high strength morjoints that had separated. New England tar with NEDC Type E mortar admix. Dry Concrete worked with the VerThe interior was pressure washed primont-based engineering firm DuBois or to applying the surface waterproofing & King Inc. on what slurry. The pressure has become the state’s washing contained Gregory Maugeri / Bill Della Sorte approved method for sporocidin (a phenoldealing with such based bactericidal, problems. Based on the virucidal, moldicidal, repairs done for similar fungicidal and tubersized and aged tanks, culocidal) as a broadrepairs were estimated spectrum disinfecting to take approximately agent. This allowed two to three weeks. workers to continue to New England work in the tank enviDry Concrete LLC ronment safely. removed all deterioThe Kryton Krysrated and weakened tol line of crystalline spalled concrete along repair materials were with any loose and used exclusively– foreign material. The requiring a cure of 72 surface was chipped hours depending on by mechanical means conditions. The tank to expose a minimum could then be refilled of 1/16-in. of new with water after 48 aggregate concrete (curing will continue). with a minimum depth of repair up to At that time, leakage testing was con1/2-in. with neat saw-cut dovetails at the ducted using the AWWA standard for perimeter. concrete tanks and disinfected using Industrial-grade corrosion inhibitors AWWA 652 Method 3. were applied to any exposed reinforceThis situation extends beyond ment that showed signs of corrosion or municipal tanks as there are many priloss of circumference, thickness or other vate and public industries that maintain The Allnex water tank
T
housands of municipalities are facing the fact that their concrete infrastructure is deteriorating. Waste, potable, and other water systems are approaching the later phases of their lifecycles. They typically show signs of cracking, positive or negative side leaks, spalling, reinforcement deterioration, freeze-thaw cycling, and all other manifestations of weathering and aging. For towns with aging concrete water tanks, the dilemma is usually the same: repair or build new. In repair, re-waterproofing can buy another decade or two so they can budget for the new expense. A solid example of this is the Vergennes-Panton Water District in Vergennes, Vermont. At 750,000 gallons, the 38-year old tank serves as the drinking water for the towns of Panton and Vergennes (serving 4,198 people); sourcing its water from Lake Champlain. According to a March 2021 presentation by the district, the water distribution system includes 54 miles of district- and privately-owned waterlines plus 3 miles of waterline owned by the Ferrisburgh Fire District. The tank’s interior dimensions are 70 by 70 ft. The standards that govern tanks vary but usually want to limit any leaking to at or below 0.1% of the total volume of
8 CONCRETE CONTRACTOR
APRIL/MAY/JUNE 2022
www.ForConstructionPros.com/Concrete
