When many of these early facilities were built, the number of weekly visitors was low, averaging five persons per week at each site. At these use levels, the volume of wastes left in pit privies could probalby be safely decomposed and assimilated by the mountain soils.
The number of people seeking primitive recreation experiences in the New England mountains has increased about ten times since the 1930's. By the 1970's, popular upper elevation sites were receiving as many as 70 overnight visitors each week during the 6 month hiking season. The volume of human waste has increased proportionately from about one gallon per week per site to 14 gallons per week, or over 300 gallons per season at some sites.
In the mid 1970's, the Backcountry Research Program of the USDA Forest Service Northeastern Forest Experimetn Station in Durham, NH, under the leadership of Ray Leonard, developed the bin composter as an inexpensive and practical means of waste disposal for high use backcountry sites. Since 1977, bins have operated continuously at selected sites in the White Mountains of New Hampshire and the Green Mountains of Vermont, as well as in a variety of other areas.
The Green Mountain Club (GMC) has played an active role in the evolution of the bin system. Out of a total of more than 60 overnight shelters on the Long Trail System, the GMC now manages eight bins at seven high use overnight sites.
The success of the GMC's bin composter program rests largely in the hands of dedicated and knowledgeable field personnel and volunteers. Organizational commitment by the Green Mountain Club ensures the continued success of the program.
The GMC bin composter system works as follows: wastes accumulate in a leakproof container under the seat of a conventional outhouse. This container is emptied at regular intervals into a storage can where the wastes are thoroughly mixed with hardwood bark from lumber mill debarking operations.
Hardwood bark has an excellent carbon/nitrogen ratio for composting; other organic materials, such as peat moss, also work. When completely broken up, the waste/bark mixture is placed in an adjacent leakproof bin. Food wastes, collected separately, are also added.
In the bin, the wastes are aerated with a turning fork, and the moisture level adjusted by adding more bark. When the bin is nearly full, a compost "run" begins. A compost run can be completed with as little as 20 gallons of fresh sewage, and as much as 60 gallons.
During the run, no new wastes are added to the bin, and the pile is turned several times. Waste breakdown occurs as local soil bacteria and fungi proliferate in the compost. Human pathogen destruction results from high temperatures and competition with hardy local microorganisms, and from processes such as oxidation and antibiosis, intrinsic to rapid aerobic decomposition.
A run lasts from three to six weeks, depending on ambient temperatures and manager skill. The compost then goes to a storage platform to further decompose for a month to a year.
Finally, the compost is scattered thinly over selected spreading sites. Compost is also recycled back through the process in place of bark.