South End Life: How Trees Stand Up to Sidewalk Repairs on Beacon Avenue

Jinny Green, who works as a Seattle Department of Transportation (SDOT) Pedestrian Mobility Supervisor, has a math mind. That's important, because she needs to know how many inches to raise the level of a sidewalk to make room for tree roots underneath. Green is supervising a project to repair sidewalks on Beacon Avenue South between South Juneau Street and South Monterey Place to ensure the walkways are compliant with the Americans with Disabilities Act (ADA).

She's also striving to retain as many trees as possible. Five months ago, the city posted notices on 69 mostly red maple and red oak trees on Beacon Avenue South, declaring that they were being evaluated for retention or removal due to sidewalk repairs. Community members asked the City to consider creative ways to retain trees.

This stretch of Beacon Hill hosts mostly single-family residential housing, midcentury builds, ramblers, and bungalows, along with churches and small businesses. During the day, you might see Asian immigrant elders walking with toddlers or practicing tai chi along the median; in the afternoons and evenings, neighbors walk their dogs and hustle between their cars and the entrances to homes. The neighborhood is historically known to house a large community of Asian and BIPOC people who were drawn to the area because they were redlined out of many other neighborhoods in Seattle until 1977. This portion of Beacon Hill is designated by the city as a high-priority tree-planting zone based on numerous factors, including tree-canopy coverage and heat-island effects.

Most of the repairs were due to tree roots elevating the sidewalk's concrete slabs, causing the walking surface to buckle and crack. As of mid-August, the sidewalk repairs were close to 75% complete, and the City has taken measures to minimize the number of trees removed. 

Of the 35 trees along the east side of the street before repairs started, only one was removed near Bethany United Church of Christ. Of 34 trees on the west side of the street, seven have been removed. Green says that for trees on the west side of South Beacon Avenue, between South Graham Street and South Monterey Place, the fate of 10 more has yet to be determined.

To Remove or Not to Remove a Tree

Nolan Rundquist, SDOT Urban Forestry city arborist, has walked a lot of Southeast Seattle, as he's planned more than 800 tree plantings in the area over decades of managing trees in the street right-of-way.

He says the trees along this portion of South Beacon Avenue were planted in the mid-1970s. "The Americans for Disabilities Act didn't exist [then], so they weren't concerned about how wide the sidewalk needed to be," said Rundquist. Now, the City follows guidelines, including ADA compliance with sidewalk width and slope.

As the trees and sidewalks compete for space, Rundquist says the City can't aggressively cut tree roots to accommodate sidewalks, because the roots store carbohydrates and nutrients to support the foliage in the canopy. "If we remove too much of the roots, the crown of the tree will die back to survive using the amount of roots it has left." If the tree is too stressed, it could die, or if too many support roots are affected, it could fall over.

Rundquist says the City wouldn't want to remove the trees in this stretch because "they're good size, have good canopy, and provide a lot of shade." He added, "If we replace them with smaller trees, we're not going to have the same benefit."

City Methods to Retain Trees on the Avenue

Narrowing the Sidewalk

Where the sidewalk is wider, Green says the City narrowed the walkway to 4 feet or created "cut-outs" to create more space for tree roots.

Raising the Sidewalk

Green says with a wider planting strip and more space between the curb and the private properties, "we can ramp a sidewalk up." She added, "We can build the sidewalk higher than it used to be so that it allows for the roots to be saved."

Just north of Bethany United Church of Christ, Green pointed at stairs leading from the sidewalk to private property. The City raised the grade of the sidewalk to accommodate the height of nearby tree roots. When paving a new sidewalk, Green says the City grades the sidewalk so water runs toward the street, away from private properties.

Rare Use of an Aluminum Plate for Walking Surface

Near St. Mark's Lutheran Church, SDOT used an aluminum plate as sidewalk material to preserve a tree with good canopy coverage. Green says this solution has only been used one other time in Seattle, along Aurora Avenue North.

Green says sidewalk and tree planting space is more narrow on the west side of the street, which limits options to retain trees.

The City's Approach to Replacing Trees

To accommodate trees that were removed, the City will usually create a "tree pit," providing room for a tree and its roots to spread. "The mayor's One Seattle Tree Plan directs us to plant three trees back for every healthy tree removed," said Rundquist. "One tree would go into the planting space, and ideally the other two trees would be in the immediate neighborhood." 

He says tree choices under power lines are limited to those that grow 25 to 30 feet in height. The other two could be taller when planted away from the power lines. Crews will also plant a more diverse array of trees along Beacon Avenue South to minimize tree diseases or insect attacks.

Seattle Urban Forestry will plant replacement trees this fall during planting season. "The saplings are around 1 to 2 inches in diameter and about 6 to 8 feet tall," said Rundquist. 

Rundquist says City-planted trees sport a City tag. In the spring, the City attaches a Treegator, a 20-gallon, green watering bag. City staff will fill the bag with water once a week for five years until the tree is established.

Next Steps

SDOT will be working the last .2-mile portion of the west side of Beacon Avenue South through the fall. Crews will lift the sidewalk slabs to look at the condition of the tree roots. SDOT staff will consider the grades of driveways and pathways to buildings to understand what measures they can take to retain trees. Green says the City will post tree protection notices on trees that are at risk for removal.

South End Life Bulletin Board

As Long as We're Talkin' Trees, Sidewalks, and Streets…

Resources

• Seattle's Find It, Fix It app helps when you want to report anything from clogged storm drains and overgrown vegetation in public areas to lost or found pets. 

• SDOT's site offers help on what to do if you want to garden in a planting strip. 

• Find out if a tree in front of your house is maintained by the City or is your responsibility at Trees for Seattle's information on tree location and ownership.

• Questions for SDOT Urban Forestry can be directed to Seattle.Trees@Seattle.gov or 206-864-TREE.

• The City of Seattle offers helpful maps on permits and services, traffic cameras, pothole repair, parking maps, and more.

Get Out and Play!

Seattle's Big Day of Play is this weekend at Rainier Playfield and the Mt. Baker Rowing and Sailing Center. Check out live performances, bounce houses, sports, and water activities.

Is Fido Under the Weather? 

On Aug. 20, Seattle Veterinary Outreach will offer Sick Pet Clinics at sliding scale for unhoused people or people who are low-income.