City Light workers, contractors and scientists are taking advantage of the dry, hot weather, to make good pace on the sandblasting and repainting of a trestle and truss bridges that carry the huge pipes connecting Masonry Dam with the historic Cedar Falls powerhouse.
The project started last year and involved the tricky removal and containment of toxic paint and soils inside the protected watershed of the Cedar River.
Last summer, specialized contractors completed the removal and repainting process of the Lower Truss Bridge that spans the Cedar River. This summer, the project is handling an 800-foot-long/110-foot-tall Trestle Bridge and its support towers, and a high truss bridge spanning the top of the upper Cedar Falls.
It is a massive undertaking. Because the work involves metal structures coated in older toxic paint – and soils that have been contaminated with lead and arsenic – workers must fully enclose all the structures in plastic sheeting, and contain all possible runoff from disturbed areas. The structures are in rugged terrain and much of the equipment and materials has to be delivered by hand.
Besides the logistical and environmental issues, there are also historic and archaeological artifacts near the structures. An archaeologist consultant is on site to ensure that sensitive artifacts aren’t damaged.
Workers are currently finishing the supporting scaffolding, the containment sheeting around the structures and hand cleaning all the surfaces to be treated. City Light vegetation crews have cleared branches and vegetation near the sites, and also built access staircases to make the work safer.
As work progresses throughout the summer, the structures will be sandblasted (with all the debris contained and collected) and recoated in safer, environmentally sound paints. The entire project should be complete by 2016, adding service life to the 90-year-old structures and helping to protect the quality of Seattle’s drinking water, already one of the best in the nation.