Composting Toilet at the Center for Urban Horticulture

Project Size: Large, >$1,000
Estimated Amount to be requested from the CSF: $33,000

Letter of Intent:

The UW Student Farm at the Center for Urban Horticulture (CUH) would greatly benefit from the addition of a composting toilet system. The closest facilities are located in Merrill Hall, which is not convenient to access from the farm, especially on the weekends when the building is locked. The farm hosts approximately 45 service learners in the fall and spring seasons, as well as a large number of volunteers who come throughout the year. The UW Farm also has many regular events such as academic tours for classes, and social gatherings. Needless to say, the Farm site at CUH receives a high amount of foot traffic. In addition, a children’s garden is being developed on the site and field trips will be greatly hampered without facilities in close proximity to the farm. Installing a composting toilet system would be very practical to meet the UW Farm’s needs.

            Toilet flushing is a water intensive practice, regardless of whether they are high efficiency models or not.  A composting system does not rely on any water inputs and instead only requires the occasional addition of a renewable resource such as sawdust to absorb moisture. Having a composting toilet is a significant step in helping the farm create a closed loop system by increasing the amount of nutrient cycling done on site. We currently work to compost all the healthy plant material grown on the farm- the next step in nutrient cycling is composting all the waste created by those who do the growing. After proper treatment, the nutrient rich, but harmless, material created can be used to fertilize trees and/or ornamental species on the property.

              Installing a composting toilet lends itself to student involvement at the farm in many different avenues. First, there will be involvement with the planning and help with installation. A workshop would be an ideal way to get a lot of students involved at this stage. Secondly, more research needs to be done on the uses of human compost and the best location for the toilet at CUH.  This is a significant undertaking that will require continued student involvement after the installation to do such tasks as making sure the facility is adequately stocked, cleaned, and properly functioning. We currently have a large leadership board, which includes three compost coordinators, and we anticipate that managing care of this system will be one of their future responsibilities. In the past few years, the UW Farm has seen an increase in the number of students who choose to do research and/or undertake projects on the farm. Having a composting toilet would greatly increase the capacity for more students to get involved on the farm as it could attract students who had interests beyond sustainable food production. This will take a collaborative effort across disciplines, student organizations, and individuals with expertise.

            A significant area of student engagement with this project lies in the development of experiential educational opportunities. It will create chances to learn about topics such as sustainable development and nutrient cycling.  The UW Farm is an incredible arena for exploration and learning, primarily regarding sustainable food production. The addition of a composting toilet would greatly diversify and expand the discussions that could occur on the farm. As mentioned above, many classes come to the Farm to take educational tours, having a composting toilet as part of the tour would be a great way to increase awareness about water conservation and waste. The addition of a composting toilet to the site can also serve as an educational opportunity to the broader community and further UW’s commitment to sustainability.      

             The UW Arboretum is currently planning on installing a composting toilet system; they have shared the system that they are looking at installing with us and will work with us to determine how best to manage them. To support the longevity of this project, there is the farm manager and a core of three paid students interns yearly, as well as a significant group of students interested in seeing this project be carried out. After the installation of the system, upkeep is routine and does require adequate attention, but the farm is an established program with a continuous group of students and staff involved. Additionally, the Seattle Youth Garden Works who are also operational on the CUH Farm site have expressed interest in being involved with this project; as they would also be privy to use of the toilet they have expressed that they could provide support monetarily for the upkeep as well as assist with the planning, installation, and maintenance of the system.

            The UW Farm is requesting approximately $33,000 for the completion of the project. The current system that we are interested in is the M54 Trailhead model from the company Clivus Multrum. This is an advanced composting toilet system, which includes a solar powered panel to power ventilation fans, keeping the facility odorless. The structure and toilet are above ground, while the collection/processing tank sits 4 feet below ground. This amount represents a quote given by the company upon phone inquiry, it includes all shipping and installation as well and a 10% “buffer”, meaning that this is the absolute upper limit of cost. The figure above represents what it would cost to buy this unit and have it shipped pre-fabricated to Seattle; however it can also be purchased as a kit and installed on site. This would be a less expensive option upfront, but would not be desirable because assemblage is very challenging and technical. Therefore, outside consultants would likely have to be hired and thus costs would be equivalent of buying it pre-fabricated, if not more. Also it would significantly delay the date when the composting toilet could be opened for use. 

Primary Contact First & Last Name: Sarah Geurkink