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Beyond Mixing the Pile: the
Active Composting System of the Batch-Bin Privy If the primary responsibility of a Trail Crew is to address erosion control, the primary responsibility of a Caretaker is to address human waste. This is for a simple reason: people have to go somewhere. The RMC composts human waste (rather than continuing to use the older "pit" toilets), since composting ensures that the pathogens, bacteria, and other nasty bits are safely killed off and won't contaminate water sources or affect vegetation.
Building upon decades of experience, and trial and error, the batch-bin composting system was specially adapted to the challenges of a cold, wet, short composting season. The principle is one of creating a self-insulating compost pile, reliant on active decomposition thanks to aerobic bacteria attracted to bark mulch. (For more information on the specific science of the batch-bin, visit the Appalachian Trail Conservancy's Backcountry Sanitation Manual, available at their website: www.appalachiantrail.org). This system is also used by the USFS, the Appalachian Mountain Club’s campsites and shelters, and the Green Mountain Club. In fact, we use it already at the Log Cabin! (Who remembers that project from 2005?) We also used some of the insights from the system already in use at the other three RMC camps, notably in the liquid separator that drains excess liquid from the waste to further promote decomposition. We here at the RMC Camps (Pete Antos-Ketcham and Sally Manikian) turned our new Board member enthusiasm to bringing higher standards of composting across the White Mountain National Forest to Crag, Gray Knob, and the Perch. We've had less than satisfactory results from the current toilet setup, and saw an opportunity to further the RMC's promotion of backcountry ethics. Moreover, the adaptations that were necessary were more of a retrofit than a full overhaul; this made it a simpler project to undertake. We started with Crag Camp, the easiest one to adapt, largely because the stable, flat terrain behind the outhouse meant we didn’t have to construct work platforms. The steep, ledgy drop-offs behind Gray Knob and The Perch call for construction of a workspace big enough for a 210 gallon plastic bin, a person, and the swing of their shovel. Our next step was to assemble the materials, starting with the 210 gallon plastic bins from Terracon Plastics. The cylindrical plastic composting bin we purchased was originally designed for aquaculture and has been successfully used by the Green Mountain Club for composting. It weighs about 45 pounds, is four feet in diameter and 2.5 feet high, and is covered with a custom-fabricated wooden lid. The lid vents moisture but keeps out rain, vermin, and curious guests. “Where am I sending these?” asked Joe, our salesperson at Terracon. “Randolph, New Hampshire.” That got his curiosity. Then he wanted to know what the bins would be used for. “Composting human waste at high elevation backcountry camps.” Now he was really interested, and particularly excited once he found out how the tanks were going to get there -- by helicopter. With the bins on the way to Randolph, Derek Schott began building the lids for the bins, Field Supervisor Curtis Moore assembled the materials for the drying racks, and winter caretaker Mike Foster spent an evening around the bark pile with Sally Manikian, bagging seventy-two 50 pound bags of bark mulch. Things started to come together, and the loose ends got tied on the historic weekend of July 13-14. With the enthusiastic volunteerism that he is known for, Al Sochard rallied a group of friends from the hiker community for a volunteer work day on July 13. They carried lumber, built the drying racks, and traveled up to Crag to enjoy the view and a few cold (adult) beverages. Drying racks are the last stage in the composting process where the composted sewage is allowed to further decompose and dry for six months to a year. After the material has sufficiently aged and dried, the mixture of humus and bark is sifted to capture bark chips that can be reused in the next run. Screening also catches any chunks of material that escaped decomposition. These can be broken up and placed in the next run. Finally after drying is completed, some of the finished compost is recycled into the next compost run, which helps inoculate it with beneficial organisms. The rest is scattered thinly over selected spreading sites in the woods. The day broke rainy and cold on July 14. But 50 pound bags of bark mulch and hundreds of hundreds of gallons of human waste do not wait for rain. Jamie Trombley and Hunter Hague, the two summer caretakers, picked up their spades and mixed, chopped, and stirred their way through the first batch-bin composting run at the RMC Camps. A “run” is where accumulated wastes are thoroughly mixed with enough additional hardwood bark, and recycled compost if available, to soak up excess liquid. The material is completely mixed, broken up and aerated with a turning fork, and the bin is almost full. This results in a carbon-to-nitrogen ratio of approximately 30:1 by weight, which is optimum for the composting process. Over the summer, we filled the three bins at Crag Camp, where we monitored temperatures and turned the pile once the temps dropped below 100 degrees F. During the run, no new wastes are added to the compost bin, and the pile is turned every four to five days. Waste breakdown occurs as local soil bacteria and fungi proliferate in the compost. Human pathogen destruction results from temperatures higher than 90 degrees F (32 degrees C), competition with hardy local microorganisms, and from processes such as oxidation (exposure to air) and antibiosis (antibiotics produced by microorganisms), intrinsic to rapid aerobic decomposition. Next spring, we’ll crack open the bins again, and see our first batch of humus. On a personal note, to see such a dream go from a set of conversations that Pete and I (Sally) had over the phone, via email, and in person, to actually taking place in front of my eyes…..I welled up a bit with emotion. This is something Pete has wanted to see happen since his days as an RMC Caretaker in the late 90’s. He feels very fortunate to be able to work with the Club to make this dream a reality. As Sally described it at the RMC annual meeting, we are now proudly “turning poo into dirt.”
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Yet,
in the White Mountains, composting human waste is difficult for
the same reasons growing a garden is difficult: the conditions
are generally pretty wet and cold. When the ambient outdoor temperature
is around 55-65 degrees F, you need to find another way to heat
the composting pile.