You think painting your house is a challenge? Try removing lead paint from an 11-foot-wide pipe, pressurized to 128 pounds per square inch, while hanging a hundred feet over the city’s clean drinking water supply.
That has been the work situation for contractors working to repaint the trestles and pipes that carry water from the Masonry Dam to the Cedar Falls powerhouse, in the protected watershed of the Cedar River.
Since last summer, workers have toiled to remove the lead paint applied to those structures in 1978, and to seal and repaint three metal bridges that carry the pipes across the Cedar River ravine. The new, environmentally sound paints and sealants will help to protect the quality of the water in the river below.
Workers started this summer on the smallest of the three crossings. The project required full scaffolding and a plastic pressurized enclosure to prevent the lead paint dust and chips from falling in the river during removal.
“We opted to start with the smaller truss bridges to remove the lead from over the river, and follow with the much larger trestle which will take most of a year to do on its own,” said Tom Pulford, project manager.
The first part of the job was planned for completion in late November last year, but workers found that the penstocks were leaking from rivet holes and other connections in the pipe. As a result, City Light had to drain the penstock and apply sealing epoxy to the leaking areas.
After an extensive effort to dry the surface for the replacement coating, the first bridge will be finish painted in the next two weeks, using environmentally sound primer and final coating.
The first bridge is approximately 10 percent of the total project. Workers will next tackle a 115-foot-tall and 900-foot-long trestle bridge. Out of the forest setting will rise a 10-storey-tall white containment structure, wrapped around five towers and joined at the top. The work should take most of 2015 to finish.
The entire project should be complete by 2016, adding service life to the 90-year-old structures. It also will help protect the environment and the quality of Seattle’s drinking water, already among the best in the country. Taking care like this to operate in an environmentally responsible manner is just one more way City Light demonstrates why it is the nation’s greenest utility.