The city of Bremerton on the western shore of Puget Sound has scored a serious environmental achievement. The Navy town has become Washington’s first city to unravel a complicated system of mixed sewage and stormwater waste, dramatically shrinking the amount of pollution dumped into the Sound. The city recently celebrated its $50 million achievement, receiving kudos from the governor and head of the Ecology Department.

But as I explore in a story posted today on Crosscut, even as the city officials feel the love of their eco success, some of them wonder if it would have benefited local waters more to have spread that money around to other green endeavors.

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  • Bremerton’s sewage projects cleaned up what are called combined sewer overflows, or CSOs, that dump untreated waste from the city’s toilets and sinks when there are heavy rainstorms. The problem dates back to when city founders plumbed Bremerton in such a way that stormwater runoff was piped into the same system that carried sewage waste. When the weather is dry, the treatment plants can clean and release the sewage and stormwater, but when there’s a lot of rain, the system is hit with a deluge of runoff that overwhelms the treatment plant and sends untreated waste into the Sound.

    The problem is not unique to Bremerton: Portland is wrapping up $1.4 billion in projects to reduce sewage spills, and Seattle and King County are working on improvements to reduce CSO events. Vancouver, BC, is likewise working to separate its sewage system.

    There are terrific, tangible benefits to reducing the release of raw sewage into Northwest waterways. After Bremerton cut the volume and frequency of spills, the state Department of Health determined that nearby shellfish beds were clean enough for people to harvest. That meant that after being off limits since the 1960s, the Suquamish Tribe, which has rights to harvest manila and little-neck clams from Dyes Inlet, could dig and enjoy these shellfish.

    Clams courtesy of Flickr user angelanoel under the Creative Commons license

    “It’s been real encouraging to us that we could get this to happen,” Leonard Forsman, chairman of the Suquamish Tribe, told me in an interview.

    Clearly, that marks an environmental success. But there’s a little wrinkle to the story. The shellfish beds were deemed clean enough to reopen in 2003 after the city had spent about $33 million on the projects. But the sewage/stormwater work in Bremerton continued until this year, with a total price tag of about $52 million, paid mostly by the city’s utility customers.

    As I note in the Crosscut story, the combined sewer overflow project was on par with other recent investments in major infrastructure in Bremerton, “including $49 million spent to build a 1,000-foot tunnel from the ferry terminal, or the $60 million that’s budgeted for the replacement of the 1,600-foot Manette Bridge.”

    Still, the cost-benefit question is worth some attention. The matter is best understood by looking at this chart that shows how much money was spent cumulatively over time and how the number of annual sewage spills declined at the same time. As you can see, even by 2000 and $18 million in improvements, huge environmental gains had been made.

    In an interview with city officials, they wondered if instead of spending an additional $20 million or $30 million on sewage projects if it would have helped the environment more to spend that money on the clean up of stormwater, which carries a large load of toxic chemicals. They also speculated that it would do more to help another community make its initial CSO fixes, rather than to keep improving their system.

    The improvements should allow Bremerton to reach the state benchmark for sewage overflows. Washington regulations allow no more than one overflow on average from each sewage outfall. The state Department has some flexibility in enforcing that standard in that it determines how many years are included in the average. The more years, the greater chance of wet and dry years balancing each other out and meeting the one-spill goal.

    Another interesting question is how much money could be saved by using “green” instead of “gray” technology to fix the sewage overflows. Bremerton, because it started its CSO work back in the early 1990s, relied mostly on gray tech — building additional and larger pipes, more treatment capacity, new pump stations, etc. But Larry Matel, managing engineer for Bremerton’s Public Works & Utilities overseeing stormwater projects, said that millions of dollars could have been saved by using more green technology. The trouble was, when the project got started, the green or low-impact development solutions such as porous asphalt, swales or rain gardens, green or eco roofs, were less well understood.

    As Matel explained in a report to Ecology:

    Another significant conclusion the City has come to at the end of their CSO reduction project is that LID would have most assuredly saved the City millions of dollars had the potential for LID’s role in solving CSO problems been more widely accepted at the start of this major investment ten years ago. Cities contemplating LID as an approach to solving their CSO problems will hopefully learn from Bremerton’s experience in this area.

    Keep in mind there’s no way that green stormwater projects could have completely replaced the gray fixes in cutting the city’s sewage spills. But by using more green — the city did include some low-impact development projects — Bremerton might have been able to save money and achieve its high standard of pollution cleanup.