By Don Mills, Clivus Multrum, Inc....
Thwack! That’s the sound of the job-site portable toilet door slamming as someone leaves it, glad to be freed from it coffin-like constraint and to be soon out of range of its stench. Unpleasant as are its aesthetics, put it on skyscraper job site, and you’re talking serious costs: cranes that could otherwise be lifting steel and other building materials are hauling portables up and down. The higher goes the structure, the more crane-time wasted.
At the recently completed One World Trade Center (1 WTC), they had a different idea. New York City-based DCM Erectors, responsible for the steel superstructure, asked Clivus Multrum, Massachusetts-based manufacturer of compost toilets and greywater recycling systems, to propose a solution. Clivus said they could provide odorless, flushing toilets that would not require any material to be brought down during the 2-3 year steel phase of the project. That claim was fulfilled. Together with DCM, a design was created, using shipping containers stacked three-high, that included 10 toilet fixtures and 10 urinals, six sinks, a water storage system, five composting units, and a commercial evaporator. And with heat and air conditioning. All this, to support as many as 200 workers on, potentially, two shifts.
The compost toilet has been around for many decades, used primarily in parks, green buildings and in private homes. Aerobic decomposition—the same process by which organic matter is broken down in soil—is harnessed in the compost toilet to break down urine and feces. By using almost no water, it saves a precious resource. And by converting both urine and feces into nutrient-rich fertilizer end-products, it creates a resource for agriculture. At 1 WTC, the aim was largely practical: how to maximize crane efficiency while providing a pleasant facility for workers.
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As the design progressed it incorporated three banks of shipping containers: one for the bathrooms, one for a Subway restaurant, and one as a plan room, for a total of 27 shipping containers. These became part of the crane support structure, and as the building went up, the crane and the three facilities went up with it.
What made it possible to eliminate crane time for hauling waste was the compost system and its special toilet fixture. The fixture employed for this project, called the Foam-Flush, uses 3 to 6 ounces of water per flush. With so little water needed for carriage to the composting units, it was possible to evaporate all liquid: flush water, urine, and handwashing water using the commercial evaporator. (A second evaporator was used to evaporate all wastewater from the Subway restaurant.) Feces are held in the compost unit. The biological activity in the composters, enhanced by the constant activity of compost worms, reduces the volume of feces by over 90%, and creates a nutrient-rich compost end-product. Odor from the composting units was mechanically vented high above the top of the structure. Maintenance of the systems—a monthly requirement at this level of usage—was performed by the manufacturer, Clivus Multrum.
What did the hardened iron workers think about this unique bathroom in the sky? As a breed, they tend to let their actions speak for them. I’m sure they appreciated the heated space during the long winter shifts. But what I heard most was their curiosity about the compost worms: they seemed to admire their industry.
The creativity and adventurousness of the planners at DCM Erectors were indispensible for the creation of this project. And the unique aspects of 1 WTC were also key: both its great height and its importance for New York City. And I can’t leave out those worms: without them, the whole thing wouldn’t have been possible.