March 2013, Vol. 25, No.3

Small Communities

Assessing decentralized wastewater in Santa Barbara County, Calif.

Kiernan Brtalik, Geneva Travis, Howard Kahan, Marina Feraud, Dana Jennings, and Kevin Huniu

California’s water supply is threatened by increasing demand due to population growth and rising uncertainty associated with climate change. Recycled water and onsite treatment may offer relief from these threats, but current infrastructure is a limiting factor to providing efficient water reuse near the point of generation.

A potential solution to inadequate infrastructure is the application of advanced decentralized treatment systems for water reuse. In order to assess what conditions prevent or advance the use of decentralized systems, a team of students at the University of California–Santa Barbara’s Bren School of Environmental Science and Management worked collaboratively with a local architecture firm, The Peikert Group Inc. (Santa Barbara), and a local nonprofit organization dedicated to promoting sustainability in Santa Barbara County, the Sustainability Project (Santa Barbara).

The collaborators focused their study on Santa Barbara County. A literature review and meetings with local stakeholders made clear that two of the main factors prohibiting the implementation of decentralized systems in Santa Barbara were complex and expensive permitting requirements, as well as a general lack of knowledge within the architecture and planning communities regarding how these systems function and their potential uses. To address this gap, the collaborators created a guidance document that delivers key information to aid decision-makers as they consider decentralized system options for projects in Santa Barbara County.

Bringing a technical subject to a nontechnical audience 

While Santa Barbara’s planning community has been a leader in adopting green building practices, their knowledge about onsite wastewater treatment is limited. The need to present a digestible review of both available and viable treatment options became readily apparent. Additionally, many individuals in this community expressed difficulty in navigating local permitting requirements, including the cost of having a system permitted, reconciling project time constraints and permitting timetables, and understanding which government agencies and individuals should be consulted for permitting information.

The project team conducted a comprehensive meta-analysis of the decentralized wastewater treatment industry that incorporated an extensive literature review of technical specifications and capabilities, an economic analysis considering the efficiency and effectiveness of each technology for selected scales, and a review of available life-cycle assessments for selected technologies. This offered insight into effects related to climate change, among myriad other considerations.

The guidance document was developed to help nontechnical audiences, including planners and architects, to better understand available technologies and determine whether their projects could benefit from implementation of an alternative, decentralized system. Eleven decentralized treatment systems were selected based on the level of knowledge within the engineering community about the viability and historic use of these systems in geographic regions similar to Santa Barbara. Each system was evaluated based on three major categories: environmental, social, and economic constraints. Each major category was divided further according to specific criteria, such as removal of total suspended solids in the environmental category and owner supervision requirements in the social category.

To deliver this information succinctly, the group created a decision-support matrix that categorizes technologies across three sections: the subsurface treatment system, constructed wetlands systems, and prefabricated and modular systems.

Technologies were scored under a “stoplight” system, with red corresponding to a low score, yellow to a medium score, and green to a high score. Additionally, a flowchart was generated to help planners and architects more easily navigate the permitting requirements for these systems, based on local regulations.

In the guidance document, each technology is accompanied by a description listing the advantages and disadvantages of the technology and an infographic (see p. 62) to help readers recall what they learned from the decision-support matrix.

Putting the guidance into action 

Each landsite development project has certain goals and limitations based on the physical characteristics of the surrounding geography, local regulatory environment, and desired use of the building. These factors influence what type of decentralized system would be appropriate. For example, an architect might desire a technology that can both create a species habitat and serve as an educational tool for children. A different architect might be interested in a low-cost system that aesthetically pleases neighbors. To help designers decide, each technology was evaluated using 21 criteria cutting across economic, environmental, and social categories.

The guidance document was used to evaluate the potential options for the Children’s Project Academy, a residential charter school for foster youth in Santa Barbara County. The academy used four major criteria to determine a potential treatment option:

  • limited land available at the project location
  • a high need to use the effluent as part of water reuse at the site
  • the potential for educational opportunities with student involvement and
  • low cost.

By using the guidance document, technologies that failed to meet the criteria for the project were eliminated. The paring left only vertical-flow and tidal-flow constructed wetland systems as viable treatment options.

The next steps 

The objective of the guidance document is to foster greater awareness and understanding about the potential of advanced treatment options to meet water reuse goals.

The document is not a stand-alone decision-making tool. Rather, it is an aid to architects, planners, and other community members in participating in educated dialogue about ways to achieve sustainability measures in their own projects.

For example, in the case of the Children’s Project Academy, now that decision-makers understand which types of systems could meet their water reuse goals, they can engage more substantively with engineers and construction experts, using specific project constraints to determine the exact feasibility of these technologies. Additionally, the permitting flowchart helps alleviate uncertainty, eliminating many of the permitting barriers that previously hindered the introduction of these systems.

The guidance document is available through The Sustainability Project. Because the project is a highly visible organization among green builders in Santa Barbara County, knowledge about the potential use of these advance technologies has increased. Architects and planners now have access to an easy-to-use information source to help guide their projects to achieve their goals of sustainable water management.

The guidance document is available online.

Kiernan Brtalik is a staff scientist at AMEC (London); Geneva Travis is a management consultant at Red Oak Consulting, a division of ARCADIS (Amsterdam); Howard Kahan is an environmental scientist at the U.S. Environmental Protection Agency; Marina Feraud is a Ph.D. candidate at the University of California–Santa Barbara’s Bren School of Environmental Science and Management; Dana Jennings is a facilities analyst at Lynda.com (Carpinteria, Calif.); and Kevin Huniu is an environmental planner at URS Corp. (San Francisco).