Photo 2 illustrates a shrouded drum sander with tungsten carbide abrasive elements. Typically the drum sander is used for large open areas of paint removal and the needle gun is used for complex shapes where the drum sander will not fit. The shroud is connected to the central vacuum system to ensure that all paint dust and particles are captured and not released to the environment.
The central vacuum system extracts paint particles from the removal tools into a sealed 55-gallon drum; the exhaust from the vacuum system is passed through a series of HEPA filters to ensure that no airborne lead dust is contained in the exhaust stream. The vacuum unit used at EWR was capable of operating a maximum of six removal tools simultaneously.
When a 55-gallon drum is full of paint particles, typically at the end of a shift, the equipment is shut down and the drum is sealed and removed from the central vacuum system and replaced with an empty drum. It’s then disposed of as hazardous material by a licensed hauler. A third party monitoring firm was used to confirm that air quality in and adjacent to the working area was less than the OSHA mandated Action Level of 30 µg/m3. The permissible exposure level (PEL) for an eight-hour day is 50 µg/m3.
Waste lead and lead-containing residues (such as dust from vacuuming) may be designated hazardous wastes, as defined in 40 CFR 261, and special handling and worker training may be required under applicable sections of 40 CFR 262 through 268. Furthermore, releases of reportable quantities of lead-containing wastes or compounds require reporting in accordance with 40 CFR 302.
A stable work platform
The search for a motorized work platform to raise a two-man crew up the side of the tank, with the required paint stripping tools, always being operated from ergonomically correct positions indicated that the following equipment configurations were available:
- motorized scissor lifts operating within the tank dike area;
- motorized boom lifts of various configurations and sizes operating over the tank dike wall.
- a cable-operated work platform suspended from the tank roof (i.e., a window washing platform); and
- a newly developed modular mast supported work platform system.
A review of the technical specification for the latter item indicated that it was the optimum choice for the large unobstructed areas of the tank, while a small boom lift or a scissors lift can be used around the spiral tank stairs, or obstructions caused by tank appurtenances.
The modular mast-supported work platform system is depicted in Photo 3, installed on the side of a 369,000-gallon tank at EWR. The lift platform is 13’-6” long x 3’-3” ft high x 2’-4” ft wide (interior).This unit has a safe working load of 2,000 pounds (uniformly distributed), which is well in excess of the loads imposed by two workers.
The leveling base of the support column is shown in Photo 4. In order to provide adequate lateral stability to the lift support columns, they must be attached to the tank near the top, bottom, and midpoints. Since jet fuel tanks are full of fuel, it was not possible to weld connection points onto the tanks to link the lift columns to the tank.
An alternate method of attachment was developed. It utilizes a high strength structural epoxy to install stainless steel “cleats” to the tank shell at the correct elevation and circumferential location for each lift column. These locations are marked out with a laser, and a boom lift is used to allow the paint removal contractor to remove all paint from the tank shell where the next cleat is to be glued to the shell with structural epoxy.
The great advantage of this type of lift is that it provides a very stable OSHA-approved work platform which can be traversed from the top of the tank down to grade, producing a 12-foot wide vertical swath of stripped paint from the top to the bottom of the tank shell. Set-up and relocation of this lift system can be performed by a two man crew with no requirement for overhead lifts or a crane.
Two complete lift sets were used for the abatement aspects of this project, and one boom lift was used for abatement of the cleat attachment areas, plus areas adjacent to the spiral tank stairs and also for priming and painting the abated tank shells.
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