When the vanguard
of the expedition arrived in early March they chose a site for base that
was 1/4 mile south of and closer to the peak than the other expeditions
clustered around "British Camp". This primary camping area was occupied by
about 75 other climbers in April, who used one of the two permanent
toilets serving the area. These sturdy structures are basic Asian type
potties with a slit in the floor to receive waste. The facilities didn't
appear to have the benefit of a great deal of mainte nance and in the
normally windy conditions used toilet paper did tend to travel freely.
Simonson's chosen base had the advantage of its own water supply
and soon had its own toilet. Roger Drake, on leave from Mt. Rainier NP,
designed the structure and visited it as part of the attached trekking
group in April. Curtis Fawley was primarily
responsible for procuring and shipping the material and putting the
toilet together, with help from other expedition members.
Tibet is an excellent environment for dehydration, with considerable
sunshine and limited precipitation. The frequent winds tend to lower the
temperatures achieved in passive solar collectors, but also assist with
ventilation and odor dispersal.
The toilet was basically a
simplified version of a solar dehydrator that has operated for ten years
at Camp Muir, 10,000' elevation on Mt. Rainier. Locally available baskets
with a tight weave catch the waste under the toilet seat and allow liquids
to
drain through onto a bed of sand. The baskets rest on a support of
hardware cloth which is in turn supported by a 2X4 frame. When the basket
is full it is slid into another position within the enclosure, which has
room for four baskets. The enclosure consists of a 4'x4' pane of
clear acrylic that faces south, and also glass on the sides with roughly
18"x24" dimensions. Pile moisture was decreased by asking men to urinate
outside, easy enough given the sandy surface. The large panel of acrylic
was attached with bolts with wing nuts for easy access to the chamber.
This toilet was not designed to retain heat at night, like a
composting toilet. When it freezes at night some drying still continues by
sublimation, but the majority of the waste reduction takes place when the
sun shines. This unit was closely observ ed for only two days in April but
on one relatively calm sunny morning it achieved 100 F less than an hour
after the first rays of sun hit it at 0750 hours and reached 113 F at
1030. Typical temperatures on a day with moderate wind an d partial
cloudiness
ranged 85-100 F when ambient temperature was in the 40's.
The unit's estimated population served averaged l5 per day for three
months. When the first basket filled rather quickly it was decided to add
a large paper box next to the seat to collect toilet paper and save the
space in the baskets for just human was te. It became apparent later,
however, that the resulting homogenous mass didn't dry as readily as a
mass with toilet paper mixed in, as Mt. Rainier's toilet is operated. The
homogenous mass would dry well for the first two inches on the outside but
not w ell on the inside Occasional mixing with a long handled tool would
greatly improve the drying, but the desire to minimize operational needs
would preclude this for most groups. It is likely that the addition of
toilet paper both lowers the initial moistur e content and provides some
wicking action during drying. When the waste was burned at the end of the
expedition the more recently used baskets with less drying time didn't
burn as easily as was desired, while the older baskets, especially those
with toil et paper inclusion, burned well.
The lack of capacity
for toilet paper in this design was partly due to the fact that the
readily available baskets, which originally transported vegetables, did
not make the best use of floor space in the enclosure. The taper at the
bottom of the baskets meant that about 30% of the possible volume was not
available for receiving waste.
An option that could have been
explored was giving the waste to local farmers for use in the fields. This
land disposal is common practice in Tibet and farms are located not far
from base camp, but concerns about transportation of waste overcame this
poss ibility. If this was done, it's assumed that toilet paper should be
excluded.
In summary, this simple dehydrator offers one way for a
medium to large expedition to manage its human waste in a base camp. The
unit can be made of inexpensive materials or longer-lasting ones such as
pressure-treated framing, marine grade plywood, Lexan
glass, and stainless steel hardware cloth, which would result in a longer
lasting structure. One of the design criteria for this location was the
realization that most unattended buildings would be dismantled by the
locals for the materials in short orde r.
The following are
alternatives to fit the sizing of the structure and the final disposal to
expedition size. 1) Use baskets without taper, add TP to baskets, and
upsize the toilet enough to have 6 baskets inside the glass. These baskets
should burn well a nd handle an expedition of this size. 2) Use 4 tapered
baskets, exclude all TP, and find a yak driver who wants the waste for his
farm. Alternatively the waste could be double bagged and trucked out. 3)
Mix homogenous waste weekly to assist drying. 4) Som e combination of
these ingredients.