Seattle Public Utilities hosted a meeting with Ballardites Feb. 23 to discuss the progress of the Ballard Natural Drainage Systems Project that will one day prevent one million gallons of storm water from entering Salmon Bay.
The meeting was held at the Loyal l Heights Community Center and Ballardites showed up with questions about the project.
SPU representatives Emily Reardon, Grace Manzano, and Rachel Garret presented the progress and project changes to neighborhood members.
Since a project update last November, SPU has decided on a new garden design that has more capacity and changes the number of beds (cells) needed for the project. The new design is a modular subsurface cell system that extends underneath sidewalks, providing more space for water containment. Because of the added capacity, now SPU has determined that 17 city blocks are needed instead of the 22 originally planned. 40 cells will be constructed on those blocks. The 17 blocks were determined a ‘best fit” by the soil composition in the areas and already placed utilities. In projects like this, SPU aims to cause the least amount of infrastructure disruption as possible.
SPU’s end goal is to reduce overflows to one per year by capturing
95 percent of storm water during a Seattle storm. The overflows happen when storm water runoff overwhelms Ballard’s combined overflow sewage system. Millions of gallons of runoff enter Salmon Bay via overflow sites. 10 percent of that water is raw sewage. In 2013, Ballard accounted for over one-third of the entire City’s overflows. That year Ballard overflowed 58 times, totaling 14.9 million gallons of combined sewer runoff.
Cells for the project have two styles: Side Slope Cross and Bulb-out Cross. The Side Slope style will be located within blocks, while the bulb-out style will be used at corner locations. The bulb-out style not only retains more water, but also provides safety improvements to intersections.
“Ballard in general has really wide planting strips (area between the street and sidewalk) much wider than I’ve seen in other parts of the city, which is nice; so even in the side slope design, which is smaller than the bulb design, we are still able to capture quite a bit of drainage in each one of those,” said Reardon.
SPU has partnering with SDOT’s Safe Routes to Schools Program and the new cells will help with intersection safety improvements by shorting the crossing and widening the sidewalk where ever they can. The bulb-out beds will improve safety because they shrink the distance between intersections.
“It (bulb-out cells) shrinks the distance from corner to corner. If somebody is crossing the street at the corner, there is more visibility overall. Oncoming traffic can see them, and they can cross safety,” said Manzano.
“The nice thing about the Safe Routes to School Project is that we heard from the community that people are speeding through certain areas, and this will make a safer environment overall for the kids trying to get to school,” said Reardon.
In addition, SPU has partnered with SDOT for work along 17th Avenue Northwest. The street is the site of a new Greenway and cells planted here will improve visibility and slow down vehicle traffic.
What about parking?
One issue Ballardites seem to be most concerned with is if they will lose parking spaces on their block.
“Parking is a big concern in Ballard, and we are meeting that concern and not taking away any legal parking spaces,” said Reardon.
SPU explained that they would not be taking away “legal” parking spaces by constructing the bulb cells at the corners. However, with the construction of the cells, drivers will no longer be able to park illegally in the 30 feet from intersections.
“The design with the curbed bulb is definitely better. We try to achieve as much bottom area, so anywhere we can actually hold and retain drainage is best. Ideally we would like to bump out the curb in lots of areas but because parking is so valuable in Ballard we chose to take different steps.”
SPU is also concerned with functionality when designing the beds, that’s why in some beds there are walkways provided so people parking along the beds will be able to walk across the planting strip. SPU said they would like to provide a walkway every 40 to 50 feet, which is typically the length between parcels. Driveways count as walkways for each property.
How did SPU decide where to place the cells?
Soil testing from 2012 revealed favorable soils under the blocks chosen for the project. SPU looked for outwash soils because of better draining rates, rather than fill or glacial till soils.
“Since then (originally testing) we have done additional soil testing (GEO-tech work), and identified underground utilities that have changed the plans a little bit. … Because Ballard is fairly level, some of the streets that we eliminated from the project were areas where we encountered fill soils,” said Manzano.
‘We try to do the least amount of impact when we are building, so if we don’t have to relocate a sewer or gas line we try to avoid them as much as possible. There are some utilities that will be relocated but it’s not blocks and blocks that have to shift.”
An SPU map of the project reveals cells planned to be constructed on 26th Avenue Northwest from Northwest 83rd Street to Northwest 77th Street, along Northwest 75th Street from Jones Avenue Northwest to 17th Avenue, and on 17th Avenue Northwest from Northwest 77th Street to Northwest 83rd Street. Readers should check the map here for other cell locations.
What will be planted in the cells?
SPU has three different plant palates that will be used: Forage, Foliage and Bulb-Out. SPU surveyed the residents living in affected areas and gathered consensus on what they might like to see. Many of the plants are the type that can withstand an abundance of water. The plants in the three palates are distillation from the plants approved was gathered from the Green Stormwater Infrastructure plant palate and meet natural drainage functions. Just a few plants Ballardites can expect to see from the listed 42 in the palates are Tufted Hair Grass, Kelsey Redstem Dogwood and Angenlina Stonecrop. Once the beds are designed, SPU will be responsible for maintenance.
The project is at 60 percent completion of the design phase and construction is expected to begin this summer. Ballardites can expect more updates from SPU closer to construction.
