By Jamie Manley, Stormwater Management Team
Portland, Oregon has one of the nation’s oldest and most successful green infrastructure programs. Many of the city’s stormwater management initiatives fall under the Grey to Green program, which promotes a variety of best management practices such as constructing green streets, controlling invasive plants, and replacing culverts. Portland also has a stormwater fee rebate program called Clean River Rewards, which incentivizes residents to increase the amount of stormwater disposed of on-site. Because EAF stormwater group is primarily interested in how to promote the adoption of green infrastructure on private property, this post will look at four mechanisms Portland has in place to increase green infrastructure on commercial and residential land: redevelopment requirements, a stormwater fee rebate, green roof floor area bonuses, and downspout disconnections.
In the long term, Portland’s redevelopment requirements may have the greatest impact on the adoption of green infrastructure on private property. New development or redevelopment projects with over 500 square feet of impervious surface must be built to adhere to Portland’s Stormwater Management Manual, which specifies a system of stormwater management that all properties must install. In addition to traditional off-site disposal to a river or combined sewer, newly developed properties are required to incorporate both surface and sub-surface disposal techniques for capturing stormwater on-site. Surface disposal techniques include vegetated swales, rain gardens, and rain barrels, while sub-surface disposal techniques include drywells, soakage trenches, and sumps. Although these regulations guarantee that best management practices are incorporated into new developments, it is also important to find ways to install green infrastructure on existing properties.
A second mechanism Portland uses to increase green infrastructure on private property is its Clean River Rewards stormwater fee rebates. Portland has a stormwater fee that homeowners and businesses pay based on the amount of impervious surface on their property. Clean River Rewards allows property owners to reduce their stormwater fee by up to 35 percent by installing green infrastructure, with the discount amount varying with the amount of stormwater captured on the property. Property owners have a variety of options for green infrastructure installations, but the city recommends a combination of surface and sub-surface disposal techniques. Green infrastructure installations are monitored by the city through random visits, and fees up to $250 can be imposed for failing to maintain the infrastructure properly. Soon after the program opened in 2006, Clean River Rewards had 14,000 participants, and the city hopes to eventually attract over 100,000 participants.
In additional redevelopment requirements and the Clean River Rewards program, Portland encourages the construction of ecoroofs through its Grey to Green program. Ecoroofs help reduce stormwater runoff by converting impervious roof space to vegetated areas that can detain stormwater. Portland encourages developers in the downtown area to add ecoroofs to buildings in exchange for an increase the allowable building area on a plot of land. Additionally, the city funds $5 per square foot of new ecoroof construction. As of 2011 the city has 6.5 acres of completed ecoroofs, and by 2015 they hope to increase this number to 43 acres.
Finally, between 1993 and 2011 Portland had a very successful downspout disconnection program that prevented water from roofs from entering the sewer system. The program offered free assistance to any residents who wished to disconnect their downspout, or paid $53 to residents who disconnected their downspouts by themselves. Over the course of the program, 56,000 downspouts were disconnected on over 26,000 properties, preventing 1.2 billion gallons of stormwater from entering the sewer annually. The program ended in 2011 because the majority of downspouts in the city had been disconnected.
Portland’s wide range of programs encouraging green infrastructure on private property have helped greatly reduce runoff pollution and combined sewer overflow across the city. Other cities looking to implement green infrastructure programs should look to Portland’s comprehensive system of green infrastructure incentives for guidance.