Three years after King County announced two very different plans for reducing combined-sewer overflows at two West Seattle pump stations, both projects are about to go into the major construction phase.

The county hosted a pre-construction meeting back in November (WSB coverage here) for the CSO project in the Murray basin, a million-gallon storage tank across the street from Lowman Beach.

And now, the Barton basin project – 91 roadside raingardens on 15 blocks in Sunrise Heights and Westwood – has just had two pre-construction meetings. The project map has been updated, showing construction on eight blocks this year, seven blocks next year, and five more blocks in reserve if needed:

We covered the first meeting Thursday night at Westside School (WSB sponsor), which was followed by a Saturday morning session at Neighborhood House’s High Point Center.

Thursday night brought a scene very different from an early project meeting in the same room a few months after the plan was first unveiled.

That meeting (WSB coverage here) filled the room; Thursday night, turnout was sparse. But the time between has featured numerous meetings and other types of outreach. Even this one was explained more as a chance for residents to talk one-on-one with project reps, if they still had questions, than as a big-group event. Nonetheless, those who showed up were given a presentation with “general information about the construction process.”

Project manager Mary Wohleb reminded everyone that the goal was to reduce overflows at the Barton Pump Station to one a year, from the current four. The project area is responsible for 45 percent of the flows to the pump station, so that’s why it was targeted.

She went over the map – same one shown above – recapping that the blue-marked blocks are those set for construction this year, orange-marked blocks for next year, green-marked blocks only if needed. The raingardens are mostly at the south end of blocks, to capture where the water runs during big storms.

Some of what’s been done already and is about to happen:

-15 gas-line services were “adjusted” last summer
*24 trees were transplanted in November. Non-transplantable trees will be taken out in the next few weeks; they promise two trees will be planted for every one removed. (Trees targeted for removal have just been flagged.)
*Deep infiltration wells will be drilled starting in a few weeks, at the end of the 15 blocks involved. This will take several months, until May, and then construction begins, with steps including:

*Protecting existing trees
*Relocating water/sewer lines if needed
*Excavating
*Installing underdrains
*Installing irrigation

That’s just the first month. Then:

*Placing bioretention soil
*Installing landscaping

That’s months two through four, counting plant establishment “so they can function when water is directed to the bioretention swales.” Then they’ll do gutter-flow tests to make sure water flows well through the system. And current midblock catch basins will be “abandoned.”

One person asked how long well-building will take; answer – it’ll take less than a week to build each one.

During construction there will be:

*Parking restrictions on streets
*Traffic revisions with signs and cones to direct cars around project area
*Emergency/local access maintained
*Access for home businesses, mail carriers, waste management (might have to move where you put your containers), delivery trucks
*Pedestrian access at all times

One resident requested early notification, whenever possible. KCWTD’s Kristine Cramer promised there also would be on-site help to direct people around the area. “The real active construction phase is about two months per block,” residents were told, with work hours typically 7 am-5 pm, though that might vary by season “to take advantage of daylight.” And when a block is under construction, they will hear from the project team “a lot,” they were promised. There’s an e-mail list and there’s a project hotline – 206-205-9184, that will be answered around the clock. Every project inquiry will get individual attention.

Then another concern that had surfaced three years ago – maintenance. Wohleb promised that the county has “dedicated funding for ongoing maintenance” and will come out from time to time and will do maintenance as needed.

In the beginning, the county warned, raingardens are “going to look more like soil than plants.” Finally, 3 to 5 years post-construction, it will look shrubby.

At 3-5 years, it will look shrubby.

And by the way, any area homeowners – not just in the raingarden blocks, but anywhere in the Barton basin – can check out voluntary green-stormwater infrastructure via RainWise, the voluntary incentive program to capture roof and yard runoff, offering rebates for installation of cisterns and home raingardens – already more than 20 in the area, and the opportunity for many more.

Shortly after that, the meeting returned to the format with which it had begun – project reps at tables around the room, answering questions one-on-one.

The toplines of what’s next are also in the project’s latest newsletter – downloadable (PDF) here.

And other parts of the area will likely want to pay attention – since other green-stormwater-infrastructure projects are in the early planning stages.