Sustainable Construction Practices

Portland Mall project uses "green" building methods and materials

TriMet has a commitment to protecting the environment that ranges from business and vehicle operations to maintenance facilities and construction initiatives. This commitment began with construction of Interstate MAX Yellow Line. TriMet is now implementing numerous sustainable measures on the Portland Mall Light Rail Project.

Reducing emissions

These measures include an innovative pilot program to generate wind and solar energy at the Jackson South Terminus, discussed in detail later. Additionally, project contractor, Stacy and Witbeck/Kiewit Pacific, A Joint Venture, is using a B20 biodiesel blend (20 percent biodiesel, 80 percent petroleum diesel) in its construction vehicles, reducing the emission of carbon dioxide and toxic compounds into the air.

Reclaiming materials

TriMet and its contractor are working to salvage, recycle and reuse materials on the Mall. In addition to reducing landfill waste, this strategy conserves resources by minimizing the amount of new materials needed.

Approximately 30,000 cubic yards of concrete, existing aggregates and base material will be crushed or cleaned and reused. A portion of granite curbs, gutters and fountains will become base material, walking paths and driveable surfaces at the South Terminus and many of the curbs and gutters will be incorporated into the landscape design. Some granite curbs also will be reinstalled on the Mall, and granite gutters will be transformed into bus stop “welcome” pads.

Cast iron tree grates, inlet frames for stormwater and wooden benches will be refurbished and returned to the Mall. The city of Portland will reuse concrete trashcans, bike racks and bike lockers at various locations throughout the city.

The current shelters were built as single components at each location, making their removal and restoration a financially unviable option. The shelters’ steel, bronze and metal parts, however, are being salvaged. Existing twin ornamental lighting fixtures will be refurbished and replaced on the Mall to the greatest extent possible.

Street trees and landscaping

Tree preservation is a project priority. Light rail construction along 5th and 6th avenues requires the removal of approximately 194 trees. An estimated 537 trees will remain intact and 127 new trees likely will be planted. Because native trees are not well suited to the urban environment, project partners selected trees for the Mall that were able to thrive downtown with canopies that allowed light to reach the sidewalk area and are tolerant of the urban environment. Urban Timberworks will salvage several of the removed trees to use as materials for furniture and residential structures. Other trees removed during construction will be used as lumber and bark mulch.

TriMet also is adding landscaping that includes visually appealing planting strips and bioswales for water filtration that will treat the stormwater from the street, tracks and light rail operations. Water treatment planting strips also will accompany the new extension of the brick from Market Street to the South Terminus.

North Terminus

In an effort to reuse rather than rebuild, TriMet purposefully designed the North Terminus around the employee facility adjacent to Union Station. The building will be retained as a useful facility in the new project. TriMet also will bring new life to an historic structure in the North Mall. The former railroad vector control building at Union Station will be renovated into a substation and communications facility for the light rail, making this culturally significant building functional once more.

Jackson South Terminus

At the Jackson South Terminus, TriMet is designing green features into the design of the systems buildings' exterior wrap treatments. Designated by the City of Portland as a gateway to the city, the terminus will become an educational space with renewable energy sources and stormwater filtration measures that will be highly visible throughout the site.

Photovoltaic panels are included on the exterior structure of the new substation and communication buildings. Working in conjuction with Portland General Electric, this signature pilot program will generate more than 50 kilowatts of power through renewable solar energy. Additionally, the proposed design calls for 22 wind turbines to be mounted on top of the light rail’s catenary poles, providing an additional 275 watts of power. The renewable energy will be fed directly into PGE's power grid, but will generate enough power to run LED site lighting, lights for illumination of the exterior screen wrap and the buildings’ electrical systems. TriMet and Portland State University will monitor the energy output from the site’s alternative power sources and report on its performance.

Also, working with the City of Portland's Bureau of Environmental Services and Department of Transporation, street stormwater runoff will be treated through bio-filtration planters along SW Jackson Street. TriMet is providing an innovative bio-filtration planting and landscape area within its property that will effectively treat all on-site stormwater. The South Terminus site also will use many salvage materials from the Mall project, including granite pavers, crushed concrete, rock and mulched tree materials.

Building off its experiences with Interstate MAX Yellow Line, TriMet remains a national model for environmentally sensitive practices with its work on the Portland Mall.