When Portland’s Tri-County Metropolitan Transportation District of Oregon (TriMet) began construction on its fifth light rail line, the agency took “green” practices to a whole new level. The construction of TriMet’s new Green Line, which opens in September, includes the reuse of materials, incorporation of renewable energy, and installing stormwater treatment features, making the line a model of the agency’s commitment to environmental stewardship.

“Our commitment to protecting the environment touches every aspect of our business, from our facility and vehicle operations to our maintenance and construction initiatives,” said TriMet General Manager Fred Hansen. “The new Green Line more than fits its name—we’ve addressed water, soil, and air quality issues with innovative measures that impact the sustainability and livability of our region.”

Reusing and Reducing Materials
During Green Line construction, which started in early 2007, TriMet and its contractors found ways to reuse materials onsite and to reduce the use of new materials. This strategy reduced landfill waste, conserved resources, minimized the amount of new materials needed, and reduced emissions generated by manufacturing and transport.

During the project, approximately 30,000 cubic yards of concrete, existing aggregates, and base material were crushed or cleaned and reused, including curbs, gutters, and fountains, which became walking and driving surfaces and part of the landscape design. Boulders removed during construction were given to the Oregon Department of Fish and Wildlife and the City of Portland to use in park settings and habitat restoration.

Contractors refurbished and replaced existing ornamental lighting fixtures, cast iron tree grates, inlet frames for stormwater, and wooden benches and salvaged steel, bronze, and other metal parts from old bus shelters.

TriMet relocated approximately 1,810 feet of its existing sound walls and installed nearly one mile of new sound walls, selecting a unique product with a composite plastic shell filled with recycled, chipped tires. Creation of the new sound walls diverted a total of 9,030 tires from landfills.

Energy Efficiency
TriMet plans to incorporate green features in the Green Line’s downtown terminus and make it an educational space with renewable energy sources and stormwater filtration features. The planned installation of photovoltaic panels will generate more than 50 kilowatts of renewable solar energy. Additionally, TriMet expects to install 22 wind turbines on top of the light rail’s catenary poles to provide up to 1,760 watts of power. Approximately 70 percent of the site’s electrical use will be powered by renewable energy.

To conserve energy at a new 750-space parking garage along the line, TriMet enrolled in the Energy Trust of Oregon’s New Buildings program. The program’s financial incentives enabled TriMet to install a lighting system that will save more than 496,000 kilowatt-hours a year—almost five times the efficiency of a standard code-compliant lighting system and equal to the annual average electricity consumption of 44 U.S. households.

Trees, Landscaping, and Stormwater
Tree preservation and replacement were among TriMet’s priorities for the project, which included the planting of more than 1,200 trees. TriMet also added 5.2 acres of diverse landscaping designed to flourish in an urban setting with minimal maintenance, and installed 290 Silva Cells, a modular underground bio-retention system that improves stormwater management and encourages healthy tree growth near station platforms.

Stormwater runoff from the street, tracks, and light rail operations will be treated through bio-filtration planters and bioswales. Dry wells associated with the bioswales detain the cleaned water and gradually release it into the soil to replenish groundwater and reduce the flooding and scouring of streams and rivers.

Through its commitment to address environmental issues at every step before and during the Green Line construction, TriMet has once again demonstrated how well it understands the impacts of its operations and the importance of making sustainable practices a priority in all the agency does.

“In just a few weeks, the Green Line will be in service, connecting new parts of our region together,” said Hansen. “It will also serve as a model of how a successful sustainability program is implemented.”

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