City efforts to replace the water mains in Bankers Hill have subjected residents to road and lane closures in the past few weeks, but it's the water runoff streaming down Fifth Avenue that has residents and motorists wondering.
Even as coverage of California's worst drought in a century appears daily in local and even national news media, gallon after gallon of water has flowed from a network of pipes connected to fire hydrants between Upas and Juniper streets.
According to city contractor Burtech Pipeline, the runoff is a necessary evil brought about by the city's requirement that all water lines be decontaminated before delivering water to peoples' homes.
In this case, Burtech contractors have been flushing the white, two-inch diameter above-ground pipes they call the "high-line." The high-line taps into the main water supply at fire hydrants and other access points, running along the base of the curb going down Fifth Avenue. A temporary asphalt solution covers the high-line through intersections to protect it from car traffic.
Once the high-line is set up, chlorine is flushed through to decontaminate it, with the output of each section tested for bacteria before being deemed suitable to carry potable water. Burtech uses sodium thiosulfate salt tablets to filter chlorine from the water exiting the pipes during this process, as part of a water pollution control plan, which follows established city guidelines.
Once the high-line has been tested, the main water supply is routed through the high-line so work can begin replacing the main-line pipes running beneath the street. A Burtech project manager said meters installed at each end of the high-line monitors the overall water usage, accounting for the amount used when flushing pipes, as well as that used by the contractors when digging trenches, mixing concrete, and cleaning the streets with Bobcat sweepers following digs.
Burtech says Bankers Hill residents shouldn't experience any disruption of service, though they may experience a decrease in water pressure. But here's the bad news: the project is slated for a minimum 170 working days, meaning construction will likely continue for another six months or more.
Beyond that, it looks like this round of high-line drainage is a proverbial drop in the bucket. The same decontamination requirements hold true for the main line itself, meaning a few months down the line, in the height of summer, more than 30 blocks' worth of blue 16-inch PVC pipe pressurized to 125 psi will also be flushed, with runoff directed to storm drains along, and at the base of, Bankers Hill.
While this won't be enough water loss that the city runs dry, it does effectively illustrate the point that conservation efforts begin, and apparently end, at home.
The affected area ranges between Fourth and Sixth avenues, from Upas to Juniper streets, with work along Laurel and Kalmia extending west to Front Street. While temporary street surfaces will cover each new section of re-installed pipe, a final asphalt resurfacing will not take place until the new pipes have been flushed, tested, and reconnected to the main, at the end of the project.