Case studies  
Blackwater Wetland, Cannon Beach, OR  
In 1984, a wastewater treatment system became operational in Cannon Beach, OR, for its 1500 citizens. Discussion for the project began in 1972 and funding was found 1982. The system can handle fluctuations that dramatically climb to 6000 people during tourist season. The total cost of the project was $1.5 million; 80% of this cost was covered by a grant from the EPA. The existing wooded wetland system supports a four-celled lagoon complex followed by two eight acre wooded wetland cells. It is operated by one part time staff and a student summer intern. Base rates to consumers have not changed since 1983. The city has reduced discharge to local Ecola Creek, the water quality has improved and an educational program has been integrated into the site. A citizen monitored waterfowl population is enhanced and supported by this system. All this and just 700 feet from the downtown shopping district with no smell!  
   

Blackwater Wetland, Arcata, CA

  
A constructed wetland system is the cornerstone of this urban watershed renovation program serving 15,000 residents, with a design population of 19,000. This innovative plan was in response to 1974 California State Legislation and a plant proposal that was energy intensive. Experiments with different systems took place from 1972 to 1982. The final design, a decentralized system, completed in 1986, offers reduced effluent into Humbolt Bay, increased local water quality, cost savings and enhanced a pre-existing salmon restoration work. Prior to this, Arcata's waterfront was characterized by channelized sloughs, marginal pastureland, an abandoned lumber mill pond and a closed sanitary landfill. Today this waterfront consists of 100 acres of fresh and salt water marshes, estuaries, ponds and tidal sloughs. This design has become an international model of appropriate and successful waste water reuse and wetland enhancement technologies. It is also a part of the Arcata Marsh and Wildlife Sanctuary.  
   
 

Figure 1: Blackwater Wetland, Arcata, CA

  
   
Case Study 1: Sidwell Friends School, Washington D.C.


Image 1: Photo of the Terraced Wetlands (from ASLA.org)

Renovations to the Sidwell Friends School in Washington, D.C. were completed in 2007
The new design incorporates a closed loop water recycling learning labratory to treat and reuse 3,000 gallons of wastewater daily. Collectively, on-site sewage treatment, water reuse, and water-efficient native plants work together to effectively reduce the school’s water consumption by 93 percent.


Image 2: Expanded Diagram of On-Site Sewage System (source: sustainablesites.org)

Waste from the restrooms enters into an anaerobic settling tank where solids, scum and oils are separated out from the wastewater.  Next, the remaining effluent is pumped below the surface into a series of terraced treatment wetlands.  The treated water circulates through the landscape for three to five days before it is reused in the buildings toilets and cooling tower.

The completed constructed wetlands treatment system cost less than the pumping lift station that would have been required to connect to the conventional sewage system.  (7 Group and Bill Reed, Integrative Design to Green Building)


                                                                      
Case Study 2


Image 3: Night shot of the Louis Centre


Image 4: Solarium (both sources from http://www.mcdonoughpartners.com)

The Adam Joseph Louis Centre for Environmental Studies, Oberlin College, Oberlin, Ohio
Designed by William McDonough + Partners, and completed in January 2001, The Louis Centre was designed according to McDonough and Partners to be “as effective and bountiful as a tree”.  The Louis Centre’s on site treatment system is a living machine with a capacity to treat 2,000 gallons of the buildings wastewater each day by non-potable reuse. The system uses five main components to collect and treat wastewater. The following descriptions are excerpted from an article published online via the Building Design and Construction Network:

  • Anaerobic digester. Waste from the restrooms enters the anaerobic digester, where solids and fats are settled out. Anaerobic bacteria-microbes that "breathe" in the absence of oxygen-convert wastes into ammonia, methane and organic acids. Water then flows into a closed aerobic reactor.
  • Closed aerobic reactor. Aquarium pumps and diffusers aerate the wastewater, reducing the amount of remaining organic material by 90 percent.
  • Open aerobic tanks. Located in the solarium, these tanks hold plants-such as papyrus, calla lilies and willows root-that provide a habitat for protozoan and micro invertebrates.  The small critters graze on bacteria and pathogens in the wastewater.
  • Clarifier. Wastewater entering through a baffle separates into layers.  Clear water is on top and a layer of sludge formed by bacteria is on the bottom. The sludge is returned to the closed aerobic tanks while a spillway sends the water to the wetland.
  • Wetland. The floor of the solarium is an artificial wetland, stocked with plants similar to those found in the open aerobic tanks. Here, protozoan and micro invertebrates further purify the water as it seeps from the east end of the solarium to the west end, where it is piped into a holding tank. An ultraviolet disinfection unit then eliminates any remaining pathogens before the water is collected into a pressurized holding tank where it is sent back through to the building's toilets and urinals.

 
Treated water from the Centre’s living machine is also used by students to irrigate nearby gardens; where they grow a variety of edibles including lettuce, carrots, grapes and apples.