We’re finally starting to see some solid figures for the Brightwater cost overruns. Keith Ervin at the Seattle Times reports:

Tunneling overruns have reached $178 million but are likely to top $200 million, Griffith’s company, R.W. Beck, reported Tuesday.

In other words, the sewage conveyance portion of the Brightwater project is looking at something on the order of a 20 percent cost overrun, give or take. (The Brightwater project consists of two major portions: 1) a new sewage treatment plant that went pretty much as planned and 2) a “conveyance system” composed of a series of tunnels and outfalls, which has experienced some difficulties.)

It hardly needs saying, but the Brightwater tunnels deploy the same kind of boring technology that will be used under downtown Seattle, where many questions surround the potential for cost overruns.