Green Roof atop Seattle’s City Hall
New legislation in Seattle will provide tax incentives for environmentally helpful landscaping within the city. What is environmentally helpful landscaping? That remains to be interpreted as the legislature pans out. According to the Washington Post, Seattle lawmakers recently approved a bill, called the “Green Factor,” to encourage builders to construct “green roofs,” “vegetated walls” and other features that clean the air, insulate buildings and ease the burden of Seattle’s wet climate on the city’s drains and creek beds.
The initiative is modeled after standards in Berlin and Sweden and officials say it is probably the first of its kind in the nation. Not only is more vegetation aesthetically appealing to city inhabitants, there is utility to the trees. Yet as with most environmental initiatives, analysts are questioning how the specifics of the legislation will pan out—how exactly the developers will apply these incentives in the market.
For instance, under the legislation, builders may be exempt from “open space” laws if their landscaping is considered “especially helpful to the environment.” There are also incentives for planting environmentally-helpful features in public rights of way. Small spaces with more vegetation such as grasses, shrubs, and tall trees could earn developers more credit than larger, less-vegetated courtyards. Fair enough, yet it seems difficult to measure what is “especially helpful” and what is not, and how developers will interpret these categories.
Higher credits would go to the most significantly beneficial landscaping features such as larger tree canopies, vine-covered walls, drought-tolerant plants and “green roofs” topped with at least 4 inches of soil and vegetation. This extra foliage would help to soak up and naturally process rainwater, as ameliorating Seattle’s rainwater drainage is a priority.
Steve Moddemeyer, a senior adviser with the city’s Department of Planning and Development, described the principles of layering the rainwater in the natural forest setting which pre-existed Seattle.
“In such a forest, rainfall first hits the tallest trees, sticking to needles and bark. Then it might trickle down onto vine maples, still 15 feet or more above the ground. Next, it drips down onto salal, a leathery native shrub. From there, it drops onto ground-covering plants such as moss and kinnikinnick. Then, it drains its way through organic debris before reaching the soil. In a thick, old forest, the whole process can take 30 days.
In the city, it takes only a few minutes for rainfall hitting sidewalks, streets, parking lots and other impervious surfaces to pour into storm and sewer drains—often bringing street pollutants in its wake.” Water that roars into the sewer and drainage systems creates a lot of wear and tear which drives a lot of costs. Increasing the surface areas allow much more water to evaporate or be absorbed.
Yet there are mixed opinions among developers, officials, and business owners. “Because of the heavy rain [in Seattle], you don’t save any money because you have to have the same storm-drainage system you would have had otherwise,” says Bruce Lorig, senior real estate developer. The extra vegetation doesn’t absorb enough water to replace any other infrastructure, so that it would only be an added cost. He also raised another problem. The idea of “layering” vegetation “probably makes a lot of sense,” he said. But, “at Pike Market, we have a green wall area, and it is a hotel for rats—they love it there,” Lorig said. Increasing vegetation could increase the rat population in Seattle in addition to other animals and insects.
The Seattle Planning Commision questioned the accountability as to who would be maintaining trees and foliage that extended into public walking spaces. Members expressed concern about unmaintained foliage impeding sidewalks and parking strips, reducing parking spots and possibly decreasing the visibility of signs.
Yet it seems to be felt by the majority of people that introducing more environmentally-helpful landscaping into Seattle is generally a good thing; this legislature, though not perfect to either side, is a necessary “first step” in the process. Moddemeyer concludes that the Green Factor will go to show “good landscaping can be compatible with dense development—and landscaping is an element of livability.”