Promoting Green Streets

Creating the Institutional Framework for Success

Technologies and engineering are no longer the largest barriers to successful implementation of stormwater BMPs; institutional issues can create the most persistent obstacles to broader use of more sustainable stormwater practices. Projects with the most on-the-ground success are often preceded by deliberate coordination amongst critical institutional partners. This is especially true for green streets, which serve many functions and exist at the nexus of jurisdictional boundaries.

Portland's Green Streets Team

Portland has received a great deal of recognition for the success of their stormwater program; what has been less recognized is the planning and coordination that created the opportunities for success. The success of Portland's green streets program was facilitated by the Green Streets Team, a cross agency and interdisciplinary team, who developed a comprehensive green streets policy and an agenda. Portland had recognized the fact that 66 percent of the City's total runoff was generated by the streets and right-of-ways. But the City also recognized the opportunity for streets to meet multiple objectives:

  • satisfying numerous City goals for neighborhood livability, sustainable development, increased green spaces, stormwater management, and groundwater protection;
  • integrating infrastructure functions by creating "linear parks" along streets that provide both pedestrian/bike areas and stormwater management;
  • avoiding the key impacts of unmanaged stormwater typical of streets;
  • managing stormwater with investments citizens can support, participate in, and see;
  • managing stormwater as a resource rather than a waste;
  • protecting pipe infrastructure investments;
  • protecting wellhead areas by managing stormwater on the surface; and
  • providing increased neighborhood amenities and value.

The Green Streets Team assembled the players that have a stake in the design, management, and maintenance of the city streets and allowed them to work together to propose and identify approaches to satisfy the City's goals. The team first identified challenges and issues that would confront the green streets program including codes and standards that would disallow or discourage green street strategies, long term performance unknowns, and maintenance responsibilities. The Green Streets Team then focused on developing the necessary outreach, technical guidance, infrastructure and maintenance plans, and funding sources to address these barriers. The results of these efforts were then synthesized into a citywide Green Streets Policy, which was adopted by the Portland City Council in March 2007.

The team then developed communication and planning procedures for incorporating multiple bureau plans into the scheduled Portland DOT Capital Improvement Program (CIP) by, for example, coordinating Water Bureau and Bureau of Environmental Services (BES) pipe replacement projects with DOT maintenance, repair, and improvement projects.

The Green Street Team propelled Portland's early green street pilot projects into a comprehensive, citywide, multi-bureau program. The team approach established a City Council mandated policy and institutionalized green street development. It also resulted in multi-agency buy-in and responsibility by identifying institutional efficiencies. For instance, because of their knowledge of plant maintenance, Portland Parks and Recreation is responsible for the maintenance of some green streets installations rather than DOT or BES. Portland's upfront planning and stakeholder buy-in paved the way for the ongoing success of the green streets program. The Team's recommendations are being incorporated into the citywide systems plan which guides city bureaus for the next 20 years.

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Chicago's Green Alleys Program

Chicago's green alleys program is another example of institutional planning creating the framework for a successful multi-benefit environmental program. The City's 13,000 publicly owned alleys consist of 1,900 miles, or 3,500 acres, of impermeable surfaces. The alley system preceded sewer connections and was originally unpaved. As the alleys were paved over time, the lack of a stormwater outlet led to flooding in adjacent garages and basements. The City's approach to managing stormwater from the alleys took the position that the most sustainable approach was one that did not add additional stormwater to an already overburdened sewer system.

The Green Alley Program is informative for two main reasons. First, it marries green infrastructure practices in the public right-of-way with green infrastructure efforts on private property by encouraging private residents to install stormwater BMPs on their property adjacent to the green alleys to increase the environmental benefits. Second, the City has used the alley retrofits as an opportunity to address other environmental concerns, thus making the program truly multi-dimensional and multi-beneficial. The main objectives of the Green Alley Program are:

  • changing the grade of the alley to drain to connecting streets rather than ponding water in the alley or draining toward garages or private property;
  • using permeable pavement that allows stormwater to percolate into the ground rather than ponding on the surface;
  • using light colored paving material that reflects sunlight rather than adsorbing it, reducing urban heat island effect;
  • incorporating recycled materials into the pavement mix to reduce the need for virgin materials and reduce the amount of waste going into the landfill; and
  • using energy efficient light fixtures that focus light downward, reducing light pollution.

The program incorporates design flexibility as alleys installed are tailored to local conditions. For instance, permeable pavement may be used for the entire alley surface. In other situations where buildings come right up to the edge of pavement and infiltrated water could threaten foundations or to save on construction costs, impermeable pavement strips are used on the outside with a permeable pavement strip down the middle. In areas where soils do not provide much infiltration capacity, the alley is re-graded to drain properly to connecting streets and impermeable pavement made with recycled materials is used.

The Green Alleys Program demonstrates the effectiveness of comprehensive environmental strategies. While the green alleys initial cost was higher than conventional rehabilitation options, they proved to be the best investment because of the multiple benefits provided in addition to solving localized flooding and reducing flow into the combined sewer system.

Photo of a green alley in Chicago.
Photo of a green alley in Chicago.

Green Alleys in Chicago (Source: Abby Hall, US EPA)


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