Fuel tanks at major airports can range in size from 300,000 to three million gallons, with a height up to 50 feet. The abatement of lead-based paint from such tanks is a very labor-intensive process. In the past it has been accomplished by installation of conventional construction scaffolding around the entire tank and enclosing either portions of the scaffolding or the entire scaffolding system in plastic sheeting fastened to the tank, to create an enclosed space within which the workers remove lead-based paint with scrapers. The paint particles fall to the bottom of the plastic enclosure, where they are vacuumed up at the end of each shift and stored as hazardous waste, awaiting shipment off site.
The most common method for repainting steel bridge structures involves removing the existing lead-based paint coatings with open abrasive blasting. This method creates hazardous air concentrations of lead, other heavy metals, and when silica abrasives are used, silica. Currently contractors are required by regulations to contain paint chips, dust, and waste abrasive materials during paint removal, typically with mesh tarpaulins or rigid structures, to protect the environment.
Unfortunately, the containment structures which control environmental emissions often increase workers’ risks of hazardous exposures to lead and other materials by concentrating these agents.
EWR’s bulk fuel farm
At Newark Liberty International Airport (EWR) the bulk fuel farm has a total of 27 jet fuel tanks with an aggregate fuel storage capacity of 16.5 million gallons. Twenty four of the jet fuel tanks were constructed in the mid-1970s, and they include a red oxide primer coat under two coats of white lead-based paint.
Contractors used conventional scaffolding and manual scraping methods for spot removal of lead-based paint on several tanks in 2007 and 2008. The project took much longer than anticipated due to low productivity.
An improved method of removing lead-based paint from the jet fuel tanks was developed and demonstrated on six 369,000-gallon jet fuel tanks in 2009. These tanks are 42 feet in diameter and 40 feet high, and are located within annular dikes which are 88 feet in diameter. Photo 1 indicates a typical configuration of a typical tank, within its annular containment dike plus the spiral tank-top access ladder.
During windy or rainy days, it is exceedingly difficult to maintain the shrouded plastic enclosure over the scaffolding sufficiently tight enough to contain all small lead-based paint particles (dust and flakes) within the enclosure. Leakage of such particles outside the controlled workspace can lead to potential violations of OSHA limitations for airborne lead dust in the workplace.
In addition, fixed construction scaffolding typically has floor planking height adjustments of two feet which do not allow the paint removal operators to use their equipment at proper ergonomic height over the entire height of the tank. This can lead to operator repetitive stress injuries or decreased productivity.
The project team focused on sourcing equipment to remove the two main impediments in the previous method of lead based paint removal, namely:
- Establishing and maintaining a means of capturing all dust particles removed from the tank surface; and
- Providing a stable, OSHA-approved motorized work platform that could travel vertically up the side of the tank shell from grade to the top of the tank and allow two workers to strip paint from an area of the tank up to 12 feet while under optimum ergonomic conditions.
Capturing lead particles
Elimination of the plastic sheeting enclosure was achieved by the use of vacuum-assisted paint removal equipment, wherein the paint is abraded by a pneumatically driven shrouded mechanical tool which has a vacuum hose connection to a central vacuum system with a HEPA filter.
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