Attachment E - Composting Toilets Standard low flow toilets require 1.28 gallons of water per flush and are the primary driver of water usage in commercial buildings. Due to advancements in technology many facility owners around the world are considering commercial-scale composting toilets. Internationally, there are real-world applications of compost toilets in commercial office buildings, a university and several environmental non-profit buildings.
The Codes The Green Plumbing & Mechanical Code Supplement (GPMCS) to the 2015 Uniform Plumbing Code (UPC) includes the approved use of composting toilets. Typically, information published in the GPMCS is integrated in the next adopted code. Staff anticipates that composting toilets will be allowed by the Uniform Plumbing Code by 2018. If approved to move forward, the City Services Building would go into service in 2019. Staff is working with the LA County Health Department to help ensure that composting toilets will be allowable by the time the building would be constructed.
Benchmark Precedent The project team visited the Bullitt Center in Seattle, a building that has been using foam-flush composting toilets for almost two years. The Bullitt Center is a 50,000 square foot, 6 story office building that is considered one of the most sustainable buildings ever built. The International Living Future Institute (ILFI) is one of its most notable tenants. The project team inspected the composting toilets at the center and discussed implementation with King County and State Department of Health regulators, Seattle planners, the project managers and maintenance staff responsible for keeping the toilets operational. Bullitt Center staff and occupants fully endorse the use of composting toilets as an acceptable water savings technology for use in a city building. Each toilet is negatively pressured at all times; air is directly ventilated through the composters and then exhausted out of the building. Occupants cite that the bathrooms with compost toilets are more pleasant due to fewer odors than standard toilet rooms. For more information on the Bullitt Center: http://www.bullittcenter.org/.
Composting Toilet Details The composting toilet technology implemented successfully in the Bullitt Center and proposed for use in the City Services Building is a foam-flush toilet that only uses 3 tablespoons of water per flush. The foam-flush technology mixes 3 tablespoons of water with Neponol, a foaming biodegradable alcoholic surfactant, to provide sanitation and the lubrication necessary to carry waste down vertical chutes that replace conventional pipes. The waste is collected in composters located in the basement of the structure. The composters are designed for passive aerobic digestion (a process performed by microorganisms under the influence of oxygen) with assistance from vermicomposting, or composting with worms. Aerobic conditions are introduced with minimal manual maintenance. Each unit requires churning (or mixing) once a week with an easy-to-use external lever to supply oxygen. Additionally, ~ 1 gallon of bulking agent (wood chips or sawdust) must be added per 100 flushes to maintain the necessary chemical balance. In approximately 18 months, solid waste will be converted to compost. The maintenance staff arranges for a permitted hauler to pick up the compost and deliver to a biosolids recycling facility. Testing requirements for the biosolid by-product would be coordinated with the Los Angeles County Health Department. Subsequent to Health Department verification, the compost will be available for mulching and distribution. More information and a demonstration of foam-flush toilets can be found on YouTube – Neptune Foam Flush Toilet: https://www.youtube.com/watch?v=ofFpVddwf04.
Proposed Project Approach
For the proposed City Services Building, the water budget is 34,000 gallons of water required per month. With the proposed use of composting toilets, the water required reduces to 15,000 gallons per month. (This represents a water savings of 19,000 gallons per month or 228,000 gallons of water per year.) The project team has calculated that the needed remaining 15,000 gallons per month could be supplied from a combination of captured rainwater, graywater and groundwater well in order to produce a net-zero water building. The proposed City Services Building would serve as a regional model of sustainability.