by Davies Hood, Executive VP, Induron Coatings
The scope of this project consisted of the repainting of both the interior and exterior of a 300,000 gallon elevated wash water tank as well as two large ground storage clearwells owned by Aqua Pennslyvania in Valley Forge, PA. The first of the two ground storage tanks was a 2 million gallon clearwell. Both clearwells are partially buried steel tanks.
When the 2 million gallon clearwell was drained , a great deal of structural damage was discovered and it was decided to excavate around the tank and abrasive blast clean the entire exterior shell – both below and above grade. The project was to be done over the winter. Approximately 16 feet of the tank wall is below grade. It was excavated in 80 foot increments and the exterior was blasted to SSPC SP10, Near White blast cleaning specifications and Permaclean 100 was applied on both the above and below grade portions of the shell.
In order to accommodate both the cold weather and the abrasion that will occur during the backfilling operation, the coating system had to be carefully selected. Induron’s Permaclean 100 was selected because:
- It could be applied in cold weather (35’F).
- It could be applied at a very high dry film thickness (25 mils minimum).
- It could be applied at that film thickness in a single coat.
- Because of its ceramic bead content, Permaclean 100 also has outstanding abrasion resistance.
The exterior roof of the tank was cleaned to the same specifications, but a high build epoxy primer was applied (Induraguard S/G Epoxy). After the Permaclean 100 was applied to the shell, the excavated areas were backfilled. An additional coat of Induraguard S/G Epoxy was applied to the above grade portion of the shell and the roof. This coat was tinted to contrast slightly with the standard gray coating used by Aqua PA on all their tanks. The finish coat was Induron’s Indurathane 6600 Plus Polyurethane enamel.
The wash water tank was completed using a more conventional exterior system (2 coats of Induraguard S/G Epoxy) followed by a finish coat of Indurathane 6600 Plus. The interior coating system consisted of a holding primer of Induron’s PE-70 Epoxy Tank Liner (applied at a DFT of 2 – 3 mils) and a finish coat of Permaclean 100 (applied at a minimum DFT of 15 mils).
This difficult job was completed on schedule and both the painting contractor and owner were completely satisfied with the performance of the coating systems selected.
The second clearwell (1 MM Gallons – also partially buried) will be done this fall (and winter), utilizing the same specifications.