April 28, 2005
Show off your stormwater runoff
By MICHELLE MARTINAT and ROBERT MURASE
When the rain stops, the sun shines upon newly cleansed sidewalks and cars. Thoughts of rainwater have dispersed. Where did it go?
Rainwater is directed over pavement and rooftops into underground storm drain systems that have been built to quickly remove water and prevent flooding. Sediment and contaminants from washing sidewalks, driveways and cars also flow through storm drains into Lake Washington, Lake Union, Puget Sound, and neighborhood rivers and creeks, contaminating fish and wildlife habitat.
Stormwater infrastructure, once hidden beneath city streets, is being brought above ground to reveal natural processes. As our water transport system becomes visible, we can grasp the connection between individual actions and water quality in neighborhood watersheds.
Visibility encourages designers to use an artistic framework to captivate attention, instill a sense of awe and appreciation, and arouse inquisitiveness. The goal of environmentally responsible stormwater resource management is to minimize and manage stormwater at the source, while inspiring exploration, interpretation and understanding of water management systems.
Below are some technologies Murase Associates has used to manage stormwater in ways that are sensitive to our region's hydrological processes.
Reducing runoff at the source
Several methods can be used to minimize runoff before it slips away. Cisterns capture runoff from roofs and/or pavement for use in irrigation and building heating, cooling and plumbing systems. The water can also be used to recharge natural groundwater aquifers.
Stone, gravel, porous concrete and pavers allow stormwater to percolate through and infiltrate into subsurface drainage systems or the ground. This reduces stormwater runoff and filters out sediments. Permeable paving materials can be used in the construction of plazas, garden walks, seating areas and parking areas.
During a rainstorm, green roof soils and plants absorb water then evaporate it over time. Green roofs decrease stormwater runoff, save energy, reduce pollution and erosion, absorb carbon dioxide, cool urban heat islands, filter air pollutants, and provide habitat for insects, birds and other wildlife.
Slowing down stormwater
Once stormwater is captured, it can be treated on-site in ponds, planters, gardens and bioswales. Stormwater ponds collect, retain and filter runoff during and after a storm. The pond's natural chemical, physical and biological processes remove suspended solids, metals and dissolved nutrients.
At the Portland Water Pollution Control Laboratory designed by Miller|Hull Partnership and SERA Architects, we created a series of artful ponds with natural eddies for native plants to grow and provide wildlife habitat.
At Buckman Heights Apartments in Portland, stormwater is captured in contained planter boxes, courtyard swales and dry wells, making it unnecessary to connect the site to the city's storm sewer system. Topsoil, gravel and plant material capture, retain and treat stormwater.
Abundantly planted bioswales visually soften paved areas, reduce polluted stormwater and educate users about stormwater management techniques. Bioswales slow the flow of stormwater into storm drains and allow pollutants to settle and decompose to decrease sedimentation. Vegetation filters oils and other pollutants. Large planting beds designed as swales can absorb stormwater from a building's downspouts.
Murase Associates used an artistic approach to education at the Miller|Hull Partnership-designed Willamette River Water Treatment Plant and Park in Wilsonville, Ore. Directly outside a conference room and across from a picnic area, an elevated water feature exaggerates the process of aeration that takes place in natural streams. Along an educational causeway, stone artfully arranged along the edge and into the water invites visitors' participation.
Water treatment facilities are leading examples of artful environmentally conscious design.
At the Columbia Boulevard Wastewater Treatment Plant in Portland, designed by Fletcher Farr Ayotte, entire wetland and riparian ecosystems have been created to treat stormwater. Opportunities for bird watching abound due to the preservation of snags and woody debris, and the creation of migratory bird nesting habitat.
Integrating many solutions
Eco-responsible stormwater management practices can be used individually or together. The combination of several techniques can result in managing all stormwater runoff on-site.
At the Mahlum Architects-designed Evergreen State College Seminar II complex in Olympia, each wing is associated with one or more outdoor learning spaces extending into the forest. The project includes extensive green roofs and rainwater harvesting. Excess rainwater from the roofs flow through ground channels integrated with the geometric patterns of the building. As the water travels towards a detention pond, the forms and bioswales become increasingly naturalistic. Students can shortcut across a series of large stepping stones in the pond.
At the Oregon Museum of Science & Industry in Portland, parking lot bioswales visually soften paved areas and educate visitors about stormwater management. Native plants restore the natural riparian edge along the riverbank and throughout the site.
At the Portland Water Pollution Control Laboratory, an innovative flume directs stormwater from the surrounding neighborhood into a detention pond. A circular wall, varying from 2 to 8 feet tall, appears to submerge and emerge with the changing water level. The wall and water work as an integrated dynamic work of art. During times of low rain fall, the pond dries up and a circle of stone is revealed.
Put in the effort
Environmentally conscious management of stormwater runoff is an individual and a group effort. Water treatment facilities, once hidden, have become public amenities and showcases for environmental design.
Architects, engineers, landscape architects, designers and contractors can use visible stormwater management practices. Homeowners can use permeable pavements to resurface driveways, walkways and patios; and they can divert roof runoff into stormwater gardens.
If we all manage stormwater at the source, over time we can improve the quality of water flowing from our city into rivers, creeks, lakes and the sound.
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