Sidwell Friends Constructed Wetland

Sidwell Friends Constructed Wetland courtesy of Andropogon Assc.

Article is taken directly from the GREEN SOURCE MAGAZINE ONLINE:

By Nadav Malin

Sidwell Friends Middle School
Washington, D.C.

While studying aerial photographs of the hilltop campus of Sidwell Friends Middle School, the project team recognized the campus also sits atop two watersheds, both of significant ecological value. That insight led to an integrated approach to water management as the centerpiece of a comprehensive appeal to environmental stewardship that emerged through encounters with architect William McDonough, FAIA, and educator David Orr. “We started out designing a building, which turned into a green building, and that green building ended up transforming the whole school, culturally and operationally,” says Mike Saxenian, assistant head of the school and its chief financial officer.

Sidwell Friends School is split between two campuses. Children in pre-kindergarten through fourth grade attend the lower school on the Bethesda, Maryland, campus. Older students go to the Washington, D.C., campus four miles to the south, which houses the middle and upper schools. A comprehensive master-planning process for both campuses, led by Philadelphia-based KieranTimberlake Associates (KTA), determined that updating and expanding the 55-year-old middle school was the first priority. Following presentations from several short-listed firms, the school hired KTA to design the project.

To create the new middle school, the design team renovated the existing 33,000 square-foot building and expanded it with a 39,000-square-foot addition. The old and new wings meet to form a U-shaped courtyard. The primary entrance leads through the courtyard into a spacious lobby, which, together with administrative offices, connects the old and new parts of the building. Most of the facility’s conventional classrooms are retained within the original building, while the new wing offers science labs, art studios, and other special-purpose rooms.

Stephen Kieran, FAIA, notes that one of the biggest challenges his team faced was the aesthetic expectations that both the designers and the client brought to the project. “Some of the trustees had it in their heads that they could have a conventional brick Washington Georgian building and add features to achieve this level of performance,” says Kieran. Instead, the project’s green agenda led them to design fenestrations based on performance rather than a traditional aesthetic, to use wood from old wine vats as siding, and to devote the building’s central courtyard to a constructed wetland rather than a lawn. Nonetheless, says Kieran, “With everybody working together, we reached agreement in the end.”

The goal of managing wastewater on-site was accepted early, but the team’s vision of how to do that evolved. “All through preliminary design, we were anticipating putting in a Living Machine,” says Kieran, referring to a proprietary system in which wastewater is treated in a series of tanks, typically housed in a greenhouse. But regenerative-design consultant Bill Reed, AIA, argued that “a Living Machine is just another piece of equipment to fix a problem that we created.” Reed suggested the constructed wetland that became the centerpiece of the courtyard.

Wastewater from the kitchen and bathrooms flows into settling tanks, where solids are collected before the water is released below the surface of the constructed wetland. After about 10 years, the solids will have to be removed to a landfill or composted, according to Reed. Surprisingly, city officials approved this alternative wastewater treatment system quickly. The city’s health department had second thoughts at the last minute but ultimately agreed to let the project go ahead on a pilot basis. “We have a monitoring protocol that we have to follow,” reports Saxenian. At press time, the wetland hadn’t yet become fully operational.

The central wetland became the most prominent element in an integrated water-management system that begins with green roof areas that retain rainwater and also serve as garden space in which students grow vegetables for the cafeteria. With this approach, “the place is the process,” notes landscape architect José Alminana of Andropogon of Philadelphia, and the enormous pedagogical value of the sustainability agenda became a driving force in the design process. In addition to the wetland, the designers introduced more than 80 plant species, all native to the Chesapeake Bay region. The biodiversity suggests that “the landscape becomes a new faculty member,” says Alminana.

The control of water guided other design decisions. For example, the exterior cladding is a rainscreen system that includes a ventilated cavity to resist water intrusion. Interior finishes include cork, linoleum, bamboo, and wood flooring remilled from pilings extracted from Baltimore Harbor. In the landscape, flagstone was reused from sidewalks, and stone for walls came from a dismantled railroad bridge. Crediting the contractor’s initiative in locating and scavenging the stone, Alminana notes, “A project of this ilk tends to attract this kind of thing. It doesn’t happen by chance-the interest is contagious.”

Energy-use reductions were achieved with a highly efficient building envelope, lighting controls, and passive strategies to minimize heating and cooling loads. Solar chimneys exhaust hot air during the cooling season without fans, and wind chimes in the towers signal airflow. Recognizing an opportunity to retire inefficient equipment in other buildings, the team designed the middle school’s mechanical system to distribute hot and cold water to much of the campus.

While Sidwell was built under a bid contract, Kieran argues that innovative projects are better procured through a negotiated contract. “You can’t find enough bidders and subs for LEED Platinum buildings that are willing to take all the risks,” he says. With the contractors contributing to the design process, Kieran notes, they understand and buy into the importance of the green components. In this case, even before it won the bid, HITT Contracting was involved at certain points during the design phase to estimate costs and provide input on constructability, which improved the continuity between design and construction. Because the project had to be substantially completed during the school’s 10-week summer break, HITT recommended using prefabricated panels for the exterior walls, according to the company’s director of sustainable construction, Kimberly Pexton, AIA.

While HITT had previously constructed several LEED-certified projects, it entered new territory with several aspects of Sidwell, including photovoltaics and the constructed wetland. In both of these areas, dividing responsibilities among subcontractors was a challenge. If the photovoltaic (PV) provider isn’t a licensed electrician, Pexton asks, “Where does the PV guy leave off and the electrician pick up?” For the wetland, the team thought it had found a subcontractor that could manage both the landscaping and the piping, but “when they got into it, the actual plumbing aspect was more than they could handle,” says Pexton. So HITT turned that part of the work over to its plumber.

After extensive deliberation, the school elected to pursue LEED Platinum certification to serve as a beacon for the community, according to Saxenian. “We had some concern that this would be seen as frivolous, but we felt compelled by our core values and our belief in the importance of stewardship of natural resources,” he says. Although the school will not prescribe a minimum LEED rating for future buildings, Saxenian says they expect their next project, a new lower school on the Bethesda campus, to achieve LEED Gold.

The school’s commitment to using this project as a learning opportunity extends far beyond the students. A team from Yale University’s School of Forestry and Environmental Studies is studying the school to determine if the project’s green strategies have a measurable effect on student and faculty performance and health. But it will be harder to measure the long-term benefits of providing students with such a deep connection to natural systems, which is so rare in an urban setting.


Washington, D.C., between Rock Creek and Glover Archbold watersheds

GROSS SQUARE FOOTAGE: 72,500 ft2 (6,736 m2)

COST: $28.5 million

COMPLETED: September 2006



PROGRAM: classrooms, library, art/music rooms, science labs, constructed wetland, rooftop container garden


ARCHITECT: KieranTimberlake Associates

COMMISSIONING AGENT: Engineering Economics

INTERIOR DESIGNER: Interior Deisgn Resources

ENGINEERS: CVM Engineers (structural); Bruce E. Brooks & Associates (MEP); VIKA (civil)

LANDSCAPE: Andropogon Associates


WETLAND CONSULTANT: Natural Systems International


Lighting and Daylighting: Sean O¹Connor Associates Lighting Consultants, Benya Lighting Design


PREFABRICATED EXTERIOR WALL PANELS: Global Partners/ Symmetry Products Group Loewen Windows

DOORS: Algoma Hardwoods


MILLWORK: Greenbrier Architectural Woodwork WALLCOVERINGS: Forbo Linoleum



CONTROLS: Lutron Electronics