Landscape Northwest Issue Home

April 20, 2000

The Puget Sound Environmental Learning Center

A model of sustainable landscape architecture on Bainbridge Island

By DEBBIE BRAINERD
with PSELC staff and consultants

Located on 255 acres on the south end of Bainbridge Island, the Puget Sound Environmental Learning Center will offer overnight educational programs for the students of the greater Seattle area beginning in fall 2001. The mission of the center is to teach environmental and community stewardship to young people by linking ecology, technology, and the arts.

PSELC is the vision of myself and my husband, Paul Brainerd. We have spent two and a half years working with The Berger Partnership, landscape architects; Mithun Partners, architects; and Bill Isley, site planning, to integrate sustainable elements into the center’s architecture and landscape.

Numerous experienced biologists and educators have visited the site, and concur that this small piece of land - which contains a complete watershed - offers the greatest variety of ecosystems available for educational opportunities so near to an urban setting. Program curriculum will focus on natural and cultural history, offering a multidisciplinary approach to learning.

A series of wetland systems - forested wetland, scrub/shrub wetland, bog, and cattail marsh - stretch north and east from the site’s borders. Of the two types of wetlands, the bog is especially unique and features conifers that are not yet 10 feet tall-yet in all likelihood, are well over 50 years old. All the wetlands provide a rich habitat for birds, amphibians, and wetland flora, including slough sedge, native spirea, skunk cabbage, and Labrador tea.

One of the wetlands provides the head waters for the site’s most famous feature, Mac’s Pond. The pond’s waters are held at the south end by a 120-year-old earthen dam. Surrounded by impressive stands of large native conifers, the pond itself provides a home for fish, migratory birds, waterfowl, and frogs.

Cattail marsh at PSELC Courtesy of Eleanor Hamilton

At the south end of the site, a stand of madronas flourishes on the sunny and well-drained slope. Elsewhere are pacific yew, the natural source of taxol (a derivative of which is used to treat ovarian and breast cancer). Throughout the property, a diverse understory includes larger shrubs such as vine maple, Indian plum, red elderberry, salmonberry, and native hazels; smaller shrubs such as snowberry, evergreen huckleberry, and Oregon grape; and ground-hugging collections of sword and licorice fern, salal, and choke cherry.

Parts of the property provide a home for less welcome plants. Invasive non-natives such as Himalayan blackberry, English ivy, and Scotch broom permeate the heavily logged portions. In many areas, these invasive species will be removed as part of a long-term restoration project. Some areas will remain untouched for students to compare and contrast the two ecosystems and the effects by humans on the environment.

Site-clearing operations typically remove much of the organic debris from the forest floor, greatly reducing the nutrients available for future vegetation growth. Traditionally this organic debris is burned or hauled off-site and other organic materials are later imported to supplement the soil for plant cultivation. In the spirit of the PSELC project, we will compost most of the organic debris and re-use it for planting, erosion control, trail building, and re-vegetation efforts. This "bio-mass re-use" will help eliminate the need for excessive import and export of other materials on and off the site.

We will begin the restoration efforts by removing the invasive plant species and replacing them with native plants. Invasive plants choke out native species and decrease biodiversity by reducing food sources and native animal habitats. The planting of native species restores natural food sources and enhances wildlife habitat. Plans for the PSELC include a native plant nursery for propagating native trees and plants for the 255 acres. Students at the center will have the opportunity to participate in this long-term restoration project.

With 255 acres to choose from, where do you put a cluster of buildings so they have minimal impact on these diverse ecosystems? This was the core question faced by the Mithun Partners architects, Berger Partnership landscape architects, and master planner Bill Isley when we began to think about the future PSELC.

The 1967 book "Design with Nature," by lan L. McHarg, helped guide us to an answer. McHarg describes a master planning process that "asks the land where buildings should be placed." The process becomes essentially a mapping exercise. Each element of interest is mapped and drawn individually, with dark tones indicating more ecologically sensitive areas and white space or light shading the less sensitive areas.

For the PSELC property, we created separate maps for the steep buffers, soil suitability, the city's regulatory constraints, and logging history. We also considered the conservation goals of the PSELC.

Roads, parking, and paved surfaces seem to be a necessary part of developing almost any site. Yet paved and other impermeable surfaces can cause a variety of problems, most notably, an increase in the volume of water run-off that enters the natural drainage system. This, in turn, can affect downstream habitats by causing stream erosion and flooding.

Using crushed rock for parking and walking surfaces and the paving width of the roads can help to minimize erosion and decrease the impacts of water run-off. Where paving is essential, the run-off from these surfaces can be routed to a detention pond that holds the water and discharges it into the existing drainage at a slower rate. Detention ponds also improve water quality, allowing sediments to collect at the bottom of the pond, rather than drain into stream systems and, in the case of the PSELC, eventually into Puget Sound.

The PSELC will have only one short paved road, which will lead into the educational center and stop just inside the entrance. Buildings will be clustered near the site’s perimeter to reduce the need for other paved roads and utility trenches. This will minimize run-off and preserve the natural core of the site for exploration and educational programming.

Most sewage treatment plants treat to a secondary level and then release the treated water - with contaminants still present - into bodies of water such as Puget Sound. The PSELC is pursuing more advanced ways of treating wastewater by designing a constructed wetland and a "living machine." Both systems replicate the natural processes of wetlands. These processes involve an additional level of treatment that will provide water clean enough for re-use.

A constructed wetland is a human-made marsh area. Wastewater is passed below ground level into several lined and unlined basins planted with wetland plants. As in a natural wetland system, micro-organisms in the root systems of the plants break down sewage and wastewater by aerobic (oxygen-based) action. By the time water has passed through the last basin, it has been treated to a tertiary level and percolates back into the ground.

A "living machine" works much like the constructed wetland, except the tanks that the water passes through are above ground, usually in a greenhouse. Waste and sewage are diverted into a series of these tanks and broken down naturally by aquatic plants, bacteria, snails, and fish. As a final step, water passes through a UV filter which kills bacteria present in the water. Similar to the natural purification processes of ponds and marshes, the water leaving a living machine is clean enough for use in irrigation or toilets.

Rainwater hitting a rooftop typically goes directly into a storm drain, where it's mixed with sewage and other wastewater. Before it can be released back into the community for re-use, the rainwater must go through an expensive sewage treatment process.

Collecting and storing rainwater directly from a rooftop is a simple process that requires a tank or cistern for storage. The various rooftop collection systems at the PSELC will collect rainwater for toilet-flushing, laundry, and irrigation by adding a simple purification system that typically consists of a primary and secondary filter and an ultraviolet water purifier.

The intention of the future PSELC is to create an educational center that models what it teaches. Using recycled materials, sustainable architecture, and state-of-the-art technology; the PSELC will become a facility of which professional educators and local community members will be proud