Overview

The 67,000 gallon in-ground concrete sludge tank at the wastewater treatment plant serving the Arrowhead Lake Community was still functional, but an inspection revealed several concerns that needed to be addressed. The tank’s interior exhibited spalling and exposed aggregate and cracks, allowing groundwater to infiltrate the tank. We helped the client rehabilitate the tank, which eliminated any structural concerns, extended its useful life, and resulted in significant reductions in sludge hauling and fees by eliminating the groundwater infiltration.

More than 1,300 homes in the Arrowhead Lake Community, nestled around one of the many beautiful lakes in the Pocono Mountains of northeastern Pennsylvania, rely on the community’s 45-year-old 0.40 MGD wastewater treatment plant. With budgets constrained, many maintenance items needed to be delayed or skipped over the years, leaving the plant in need of repairs and upgrades.

The 67,000 gallon poured-in-place concrete sludge tank was operational, but a recent cleanout and inspection noted several problems inside:

• spalling concrete in the roof;
• exposed aggregate throughout the shell and roof;
• cracks in the wall and around pipe penetrations allowing groundwater infiltration.
  

The tank needed to be rehabilitated, but the client knew it would be costly. With almost every available dollar tied up in other necessary plant upgrades, the client struggled with the decision to invest in a tank that was still “working.” Ultimately, after careful deliberation and with our guidance, they decided to rehabilitate it now instead of later. The team, including the tank painter, I.K. Stoltzfus, worked together to select a repair procedure and coating system that would fix the cracks and stop water infiltration, while also halting the concrete degradation and protecting the exposed aggregate. After all concrete surfaces were sandblasted to clean and smooth any sharp edges, a Xypex coating system was applied inside. The tank exterior was also coated, as the roof sat above-grade. All exposed exterior surfaces were blasted and a two coat epoxy-urethane system was applied. The tank inspection firm, MBA, assisted with on-site coating inspections.

The tank was returned to service, and the client now has a water-tight structure that truly is a “sludge-only tank.” Stopping the water infiltration has reduced sludge hauling quantities by 55.5% and saved more than $28,000 over the first 10 months alone. The project investment will pay itself back within a few years.

"Sludge wasting and overall operations have improved immensely. We are so glad for Entech’s advice in rehabbing this tank now."

-Plant Operator