As described in John Holusha’s 1992 New York Times article”Technology; Improving Safety When Removing Lead-Based Paint,” contractors sandblasting the Williamsburgh Bridge allowed lead-paint contaminated sandblast dust to escape containment to settle on windowsills and playgrounds throughout the community. Residents complained and authorities called operations to a halt for more than a month.
Residents also complained in Pittsburgh. There bridge sandblasting created such extensive lead contamination that the Allegheny County Department of Health not only to called a halt to sandblasting, but were required to condemn homes located near the blast site.
Lead contamination of the surrounding community is a commonly seen in sandblasting. As noted in the SCOPe report “Lead – Bridges and Structures” “The most significant hazards of exposure to lead from bridges and structures comes about not by deteriorating, flaking and/or peeling paint – which do pose a problem – but when the paint is removed.” The CDC notes, one of the leading sources of a community’s of high dose lead exposure can be from “sandblasting or demolishing bridges and other lead-painted metal structures. These localized activities can be an important source of high-dose exposure.”
The abrasive blasting of lead-based paint poses a risk to workers as well as to the surrounding community. Operators are subject to lung disorders from breathing abrasive dust and to lead poisoning from lead-laced dust. NIOSH notes ” Respirable dust from silica sand and other abrasive materials pose a risk to the lungs. Where abrasive blasting is used to remove lead-based paint on the steel infrastructure of bridges, it can generate particles of lead that pose a risk to the nervous system.”
In addition to these health risks, the scaffolding and containment required for sandblasting present dangers of their own. In 2005, sandblasters set off a four-alarm blaze on the Queensborough Bridge. Flames from a small rubbish bin set fire to and quickly engulfed the bridge scaffolding and containment tarpaulin. The fire required 168 firefighters, 39 units and closed the upper bridge levels for more than 24-hour.
Even without a fire, properly performed sandblasting remains problematic. The process generates large quantities of lead contaminated waste sand, which is expensive to bury. Westinghouse Electric Corporation’s Science and Technology Center estimates the tonnage of contaminated sand and grit generated by blasting a medium sized bridge to be about 800 tons and the cost of disposal to be around $400,000.00.
The PENTEK® System equipped with Corner Cutters and/or Roto-Peen Scalers eliminates the need for containment, respiratory equipment, and protective suits. The Pentek System radically reduces waste generation and waste disposal costs by never generating mounds of contaminated sand. The only waste produced is chips of rust and lead-based paint. Waste disposal costs are radically reduced.
Each tool operates differently.
The Corner-Cutter®operates on the same principle as a pneumatically operated needle scaler. Specially hardened needles operate within an evacuated stainless steel enclosure which prevents the escape of dust, debris and airborne contamination to the environment. Standard shrouds are provided with each unit to allow the cutters to conform to inside corners, outside corners, and flat surfaces. Special shrouds are available to conform to particularly odd geometric shapes, such as door and window frames
The Roto-Peen Scaler uses with 3M Heavy Duty Roto Peen Flaps, each studded with rows of tough tungsten carbide cutters and mounted on a rotating hub to abrade and fracture surface coating. Paint, corrosion, oxide, and mill scale are fractured and removed by the impact of the tungsten carbide against the work surface. This 100% mechanical action occurs within an evacuated enclosure designed to prevent the escape of dust, debris, and airborne contamination into the environment.
Hazardous waste disposal costs are drastically reduced: only the paint removed becomes waste; water, or chemicals, or sand are never introduced into the stream. All the waste from cleaning 2,500 square feet of work surface can be contained in a single 55-gallon drum.
The PENTEK System has been used worldwide including resurfacing Melbourne’s Westgate Bridge.
Melbourne Austalia ‘s Westgate Bridge