A number of methods have been advanced to effectively contain blasting debris and to minimize the amount of waste generated from the management of lead-based paint from steel bridges. These methods are discussed in Art. 1.5.5 of this chapter. They can be broadly characterized as follows.
Deferring Maintenance. This approach does not serve to protect the bridge, and is the least satisfactory approach to protecting the large public investment represented by a major steel bridge.
Overcoating. This method consists of applying new layers of nonleaded paint over lead — based paint with the intent of extending the coating system for another 5 years or so. This method may reduce short-term costs and provide an agency more time while new innovations in lead paint removal are being developed. However, worker safety and environmental issues still remain with the structure until the lead-based paint is removed. For example, the volume of unleaded paint increases with each coat, and thus a greater quantity of lead-contaminated paint must be disposed of as hazardous waste in many cases. Additionally, performance of the overcoating products has been highly variable, depending on operator skill and experience, application conditions, existing paint that is being overcoated, and product consistency.
Removal and Repainting. This strategy requires the use of abrasive blasting or other means to remove the existing lead-based paint, followed by application of a coating system. This would provide the most durable and effective protection for steel bridge structures. However, its cost-effectiveness is diminished due to the need to collect and dispose of the spent paint and blasting grit of as hazardous waste. Worker safety during removal is a significant consideration.
Removing and Replacing Steel Members. This strategy involves removing members of the bridge during major rehabilitation efforts; removal of the lead-based paint within an enclosed workplace such as a fabricating shop; repainting, and restoring the members to their original location. Containment of the lead paint and blasting grit is more easily achieved with this approach. This method is generally cost-effective only on major rehabilitation projects.
