Past Project: Investigation and Analysis of Solids in Municipal Storage Tank Leads to Cleaning/Removal

Staff at the City of Helena’s Missouri River Water Treatment Plant (MRWTP) had intended to repurpose a steel storage tank previously used to store alum. Even though the tank had been cleaned, when sodium hydroxide (lye) was added to it, it created a chemical reaction that burned a hole in the tank wall and left about three cubic yards of dense foam inside. Olympus Technical Services was contracted to investigate and provide recommendations on proper handling and disposal of the material.

Olympus analyzed the solids and provided results to the City of Helena. Because the material was found to be acidic and the steel storage tank was a permit-required confined space, city personnel at the plant were not able to remove the material themselves, so Olympus was contracted to perform the work.

Olympus broke up and removed the material from the tank, bagged it in approximately 100 55-gallon bags, and transported it to a city-owned trailer outside of the building so that city staff could transport it to the landfill for proper disposal. The tank was deemed unrepairable and was tagged for scrap.

This project presented several challenges:

  • Work was conducted inside an active water treatment facility with controlled access to the property.
  • The material remaining in the tank, despite looking like foam, was as hard as concrete. A jackhammer was required to break it up for removal.
  • The solids to be removed were acidic, necessitating that level C personal protective equipment be worn while inside the tank.
  • A harness and rope were required to enter and exit the tank.
  • The work generated a lot of dust inside the tank. The filters on workers’ respirators filled up quickly so personnel had to be swapped out frequently.