(County map showing where the “green stormwater infrastructure” is proposed for the area feeding the Barton pump station; go here for larger version)
By Tracy Record
West Seattle Blog editor
There was a bit of myth-buster flavor to the first major community meeting since King County’s December announcement that it wants to solve the Barton Pump Station‘s overflow woes with “green stormwater infrastructure” in a 17-block area of Westwood and Sunrise Heights:
No, there won’t be a raingarden in front of every home in the area.
No, the raingardens aren’t expected to fill up and sit stagnant as mosquito-breeding ponds or child-drowning risks.
No, they won’t block you from getting between your street-parked car and your front door.
So – what will they do, and how?
The answers, questions, and backstory came in a well-attended community meeting Wednesday night at Westside School, which is in the project zone. (If you’re short on time – here’s the PowerPoint presentation.)
“Perfect ‘combined-sewer-overflow’ kind of night,” joked consultant Bob Wheeler, looking out the huge windows of the school auditorium, which held an eastward view of dark clouds that had recently dumped sleet/hail on the area, chased by a downpour.
The front end of the meeting was heavy on introductions and background, before getting closer to specifics about the project and a chance for Q/A.
Westside’s head of school Jo Ann Yockey offered the 70-plus-strong crowd a welcome, saying they were pleased to “open this space to the community” in their first year of operation in what had been a shuttered Seattle Public Schools elementary.
Maryann Petrocelli, King County’s outreach leader, introduced herself, noting she is a Westwood resident, though “out of the project area.” She’s the person you can call with questions or problems.
The rest of the team of consultants and county employees – same consultants as the meetings last year, but with different county employees in the mix representing public outreach and project management – started with a primer on CSOs and the timeline of the process to this point, dating back a year and a half to a community meeting in October 2009.
As project manager Mary Wohleb summarized it, if the pump station wasn’t capable of an overflow discharge into Puget Sound, the mix of sewage and stormwater during heavy rain “would be backing up into your house.” The state says overflows have to be limited to an average of one per year; the Barton station is averaging four. The “green stormwater infrastructure approach” was described as an “engineered approach to using natural drainage to capture stormwater” before it gets into the system, then “slowly releasing it” when the storm has passed.
Jeff Lykken from Tetra Tech, whose specialty is the technical side of things, dove further into explaining the combined-sewer system that Seattle and about 700 “older cities around the United States” are completely or partially set up with such systems. In the project area, everything goes into a combined sewer, which means that diverting stormwater will “make it a good target area.” This particular location also is responsible for much of the flow down to the pump station by Fauntleroy ferry dock – 50 percent of the entire “basin” flow goes down Barton, and then Director, to the pump station.
Advantages of this approach, Lykken summarized, are not just that it’s a “more sustainable solution” but also that it can be “constructed in the public right of way” (mostly inbetween the sidewalk and curb lane) and it ultimately means less stormwater going into the treatment system (from here, water is sent all the way to West Point off Magnolia for treatment).
So what exactly goes into the “public right of way”?
John Phillips from King County picked it up from there. Plants and soil – “typically a mix of grasses, native plants, and ornamental plants” – are the key components in “evaporat(ing), captur(ing) and reus(ing) stormwater.” They would be part of “bioretention/bioswales,” but there’s also “permeable pavement” and “roof disconnection” – ending the practice of having roof gutters/downspouts feeding rainwater directly into the combined-sewer system. Another advantage he pitched: This is adaptable to “unknown future weather conditions” – say it gets rainier in the decades ahead, a storage tank might turn out not to have been the right size.
He finally got to the heart of the matter, topics that hadn’t been discussed back when the concept was just theoretical – it’s not final yet, since it’s still in environmental review, but it’s close: The concerns.
Answers were offered:
PARKING EFFECTS? A “minimal reduction” is envisioned, and the county wants to work with each block regarding how they “use” parking. “Curb alignment” will be maintained “where possible, though “curb bulbs with landscape enhancements” might be added in some places where “additional (water) capacity” is needed.
ACCESS BETWEEN STREET AND FRONT DOOR? There will be “crossable zones” from sidewalk to street edge, “steppable zones” next to the curb, durable plants, and visibility.
MAINTENANCE? This is a biggie. While you currently are responsible for maintaining the “planting strip” between sidewalk and street, if you have one, even though it’s city right of way, King County will be responsible for major maintenance on the GSI features – to “maintain flow and storage … (and) longterm function. … These facilities need to last 50 to 100 years.”
LESSONS LEARNED? Wohleb said there were plenty – particularly from the city’s troubled Ballard raingarden project (which even sent a rep to this meeting, to jump in as soon as the topic came up). “That’s why we’re installing 17 groundwater monitoring wells – we need to know what’s going on underground.” They’re also surveying the neighborhood to ask people about areas with known drainage/flooding problems: “What we don’t want to do is make it worse.” They’re also going to install an official rain gauge in the area – the nearest one turns out to be a mile and a half away.
Attendee questions included: “A few of us on our block have improved parking strips – will you help us move the plants we put in?” Answer: “Yes … and if we like the plants, we just may keep them!”
This brought a smile to the face of one man who volunteered that he’s growing potatoes in his planting strip.
The next questioner had more of a statement: “If you take a pig and call them a world-class bovine … what the county wants us to do is store this rainwater in front of our houses because they are unable to effectively remove it from the area, correct?”
Phillips eventually said, “Yes.”
Then came the concern about raingardens holding enough water to be a drowning risk. Wohleb explained that’s another reason for installing groundwater wells “to determine seasonable groundwater level and infiltration rates.” If they find an area has levels/rates too high for a raingarden to be useful, that area won’t get one. Having two or three days of standing water after a storm is not acceptable, she said. (It was also pointed out that after the initial planting/growing phase, the areas will be full of plants, not open pools even if there is plenty of water.)
What kind of wildlife would the bioswales attract? someone wondered, particularly worried about mosquitoes and rats. (Eventually a loud chorus of “Raccoons!” arose from other attendees; “possums!” others added.)
Mosquitoes need 7 to 12 days in standing water, it was pointed out.
How about basements – what if you already struggle to keep your basement dry, is this putting it at risk of flooding?
Wohleb reiterated that they want to hear about existing problems like that: “We don’t want to site a bioswale in an area with existing problems.”
Another question: Would water meters have to be relocated? Phillips said they already have mapped water meters and pipes, and they either will avoid those spots for building raingardens, or work around them: “It’s too expensive to relocate water meters.”
WHAT’S NEXT: A community survey is open till May 7 – take it here. An environmental report is expected in late April, with a comment period in May. Field work and design are continuing. Outreach efforts are to include mailings, website updates, and more meetings. The final facility plan is supposed to be approved by July 1 this year, with the permitting process under way fall 2011-fall 2012, the preliminary design from this fall through early next year, final design done next year (with a conceptual design done by early March), then construction 2013-2015. Some job openings are posted right now – hydrologists, geologists, landscape-design professionals.
MORE INFORMATION: The main page for county information on the project is here.
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