Model : Bio-Sun Systems Inc. WRS 1000 PS
Compiled by : Paul Lachapelle, Sept. 1995
Toilet Installed : July, 1995



A) Composting Overview
B) The Bio-Sun System
- Electrical System
- Liquids
- Solids

A) Work Schedule
- Daily or As Needed
- Weekly
- Monthly
- Twice/Year
- Yearly

B) Other Responsibilities

C) Tools, Supplies Needed





Crag Camp is an enclosed backcountry cabin which is owned and operated by the RMC on
National Forest land under a Special Use Permit by the United States Forest Service
(USFS). The cabin and the new composting toilet are located on the western rim of King
Ravine on Mt. Adams in New Hampshire (elevation 4,250 feet). The old Crag Camp
structure was first built in 1909 and acquired by the RMC in 1939 to be used as a public
overnight facility. The structure was demolished in April 1993 due to its dilapidated state
and was completely reconstructed in the summer of 1993. The new building, which was
opened to the public in November 1993, measures 40' x 32' and has an occupancy rated
for 20 overnight guests. In addition to being a destination for overnight hikers, the structure
is used as a stopping point by numerous day hikers on Mt. Adams. Crag Camp is not
insulated and therefore the majority of overnight use is during the summer and fall months
(see Appendix, figure 1). During this warm weather period, weekends and holidays
constitute the majority of overnight use. Overnight guests are required to bring their own
sleeping and cooking equipment and must pay a $7 / night fee. A caretaker is in residence
at Crag Camp from June 1 through September 5 and works an 11 day on / 3 day off
schedule. At all other times, the RMC Gray Knob caretaker checks the camp on a daily
The facility has used a variety of different pit toilet sites and composting methods in the
immediate area for the disposal of human waste. Until recently, Crag Camp used a pit style
toilet for the collection of waste in the winter. The pit was dug out in the spring and then
actively composted in collection bins. Waste in the summer was collected in a 60 gallon
container situated beneath the outhouse structure. This waste had to be emptied and
composted periodically. In order to keep liquid content down, users of the composting toilet
were asked to urinate in the nearby woods. Large amounts of wood shavings were needed
to adequately compost the waste. The requirements for this composting method
necessitated that the mulch be flown-in.
In 1994, the Randolph Mountain Club (RMC) determined that as a result of the following
factors, 1) the number of visitors at Crag Camp, 2) the fragile alpine environment nearby, 3)
the potential increase in use of the facility, and 4) the condition of the current toilet system,
an improved waste treatment system was needed. The research following this decision
was completed by RMC caretakers Paul Lachapelle and Paul Neubauer with the help of
RMC Vice President Doug Mayer.
All possible scenarios concerning waste disposal were considered including incineration,
chemical treatment, and fly-out. The decision to compost the waste on-site and purchase
this particular system was based on conversations with USFS representatives, people
involved in backcountry toilet maintenance and manufacturers of toilet systems. Overall, it
became clear that the continuous composting technique is an effective waste treatment
method and that continuous composters are functioning well in many diverse environmental
settings, including sites comparable to Crag Camp. The system at Crag Camp will work
essentially as a containment device as ambient temperatures approach freezing. The
compost pile will reactivate when temperatures consistently average 40_ F or higher (May
to October). The RMC has oversized the composting system due to two key factors. First,
the system will actively compost for only four months out of the year due to the low ambient
temperatures. Second, high relative humidity may slow the composting and evaporation
process. The RMC wants to insure that the system is a long term solution to waste
treatment, therefore, over-sizing the unit will safeguard against the possibility of an overflow

A) Composting Overview

This composting toilet operates on the principle that the human waste within the tank, if
given enough air and time, will decompose into a soil-like material. Natural oxygen-using
bacteria (aerobes) consume harmful organisms (pathogens) within the waste. The
pathogens within the human waste are also eliminated over time when exposed to oxygen
or as a result of the competition between organisms, natural antibiotics, the loss of nutrients
and heat. The total volume of the pile is reduced as some of the mass is converted to
carbon dioxide and water vapor by the aerobes.
The aim of composting technology is to optimize conditions for microbial activity. The
essential ingredients of a compost pile are organic material, microorganisms, moisture,
oxygen and heat. The process of transforming raw waste into finished compost results
primarily from natural soil microorganisms such as bacteria, fungi and actinomycetes. Soil
invertebrates such as springtails, mites, millipedes and beetles also contribute to waste
decomposition. Adding wood chips increases the amount of organic material or carbon,
absorbs moisture and odors and provides air space and structure within the pile. This
carbon source, preferably hardwood shavings, must be added periodically in order to
support aerobic decomposition. The compost pile must also be mixed to increase aeration.
B) The Bio-Sun System
Note: the front of the tank refers to tank access door and exhaust vent area. (see Appendix,
figures 2 - 14)
The structure was built by John Tremblay and Pat Hackett and opened in July 1995. The
tank measures 51" high x 71" wide x 101" long and has a total internal area of 1000 gallons
(130 cubic foot). The tank has a total liquid capacity of 126 gallons before an overflow
situation occurs. This Bio-Sun toilet differs from other composting systems because of the
high air-flow volume and ratio of air interfacing with the waste surface. The temperatures
reached within the waste pile are in the mesophilic range (50_ F to 120_ F). This differs
from the batch or bin composting technique, which is a thermophilic (120_ F+) method.
This technique is widely used at facilities maintained by the Green Mountain Club and
Appalachian Mountain Club. The aim of thermophilic composting, which requires frequent
mixing and high wood chip input, is to kill pathogens quickly and with hot temperatures. In
comparison, mesophilic composting is a long-term method which can take years to
effectively reduce or eliminate pathogens within the waste. Mesophilic composting differs
from thermophilic composting because the mixing process is not as often and the amount of
wood chips added is much lower. Wood chips must be added to the tank at a ratio of one
full 8 oz. coffee can per 25 uses. The wood chips should be deposited through the toilet
seat. In order to maintain a consistent supply of carbon added into the tank, only the
caretaker should add the wood chips. While the caretaker may add organic food scraps,
guests should not be allowed to put food into the system.
The toilet is situated over a sealed container. Inside the chimney is a fan that is powered
by a solar (photovoltaic) panel. The fan draws air through the system. The waste is
suspended on a perforated liner and air is able to circulate above and below the waste pile.
The air enters the tank through the toilet seat. The air is then drawn into the primary air
inlet tube at the back of the tank. The air also travels along the sides of the tank and
underneath the waste pile into the perforated inlet tube running the length of the tank. The
air passes the centrifuge vaporizer unit in the base of the exhaust vent then past the fan
and back outside. The box around the tank is stained black to increase heat absorption. A
thermometer has been mounted inside the tank to monitor the ambient air temperature. A
second thermometer is situated in the waste pile to record temperatures within the pile.

inches below the top of the divider bulkhead to approximately 12 inches behind the
divider bulkhead. This will amount to about 2 cubic feet of material." Compost may
not need to be removed every year or for the first several years of operation. Early
summer is the best period to dispose of finished compost because of the occurrence
of high soil organism activity. The finished compost should be spread thinly on the
forest floor and away from the camp and water sources. Care should be taken when
handling and spreading the finished compost because of the potential that
pathogens remain. Non-organic material should be bagged and disposed of off
USFS land.
40+ Check wood chip supply stored inside Crag Camp and contact Camps
Supervisors to re-stock. The manufacturer recommends using thumbnail-size
hardwood chips (no cedar or redwood chips).
40+ The manufacturer recommends that the fusible link on the fire extinguisher be
yearly. The link is date stamped on the brass disk. Replacement links are
available from Bio-Sun. The fusible link screws into the fire extinguisher pressure
40+ Clear out ditch extending from the northwest corner of the tank to insure adequate

B) Other Responsibilities
Above 40_ F Temperatures

* IMPORTANT * The waste pile at the back of the tank should be mixed
once a month between June 1 and September 30. Using the long
handled garden hoe, rake and shovel, the pile should be turned and aerated,
intermixing wood chips with fresh waste. Additional wood chips should not be added
to the pile. The wood chips and the waste should be uniformly mixed. New waste
should be pushed to the back of the tank (away from access door). Access the
waste pile from the left side of the exhaust vent when facing the access door. Knock
off excess waste particles on the hoe into the tank and store hoe outside. Remove
any mulch material that may have fallen in front of the bulkhead divider in the float
switch area. Be careful not to contaminate yourself during the mixing. Wash
thoroughly with anti-bacterial soap afterwards.
- Dust off photovoltaic panel periodically with a cotton rag.
- The black box around the tank will have to be re-stained (not painted) every
several years Use an oil-based black stain such as Thompson's brand wood
protector. DO NOT stain or paint over the cedar shingles.
- The door and window frame will need to be re-stained with a clear wood
preservative periodically.
- Trim the tops of trees on the SE, S and SW sides of the photovoltaic panel
periodically. A small shadow on the panel will decrease the voltage output

Below 40_ F Temperatures
- Clear snow off of photovoltaic panel with a broom and from the ramp with a snow
shovel after every precipitation event. The panel should be carefully brushed but
not scraped.
- The liquid level will have to be checked in the spring and the waste cone that forms
beneath the toilet seat may have to be knocked over several times during the cold
season. Therefore, the access door area should remain free of snow in order to
access the waste pile and check the liquid level.

C) Tools / Supplies Needed

- Garden hoe
- Rake
- Long-handled shovel
- Short-handled shovel
- Snow shovel
- Broom

- Wood chips (hardwood, thumbnail size, no cedar or redwood)
- Extra 5 amp fuses (cylinder-shaped automobile type)
- Extra relay
- Anti-bacterial soap
- 2 locks with keys for access door and control panel door
- Toilet brush
- 5 gallon bucket
- 30 gallon plastic garbage can
- Synthetic 5W/30 motor oil (for vaporizer motor)
- Cotton rags
- Bleach



- A faucet attached to a hose has been installed at the access door area of the tank. If
an overflow situation is expected, the caretaker can drain liquids into a provided
bucket. The caretaker should mix bleach (store-bought brand) with the liquid. The
ratio should be 1 ounce bleach to 1 gallon liquid. The bucket should be mixed with a
stick and then stored overnight. Some foaming will occur and should be expected.
Empty the bucket into a nearby hole. The hole should be approximately 2 feet deep
and away from the camp and water supplies.

- If the high liquid light does not illuminate when test button is pressed check 1) that
there is adequate sunlight, 2) the fuse in the control panel, 3) the light bulb, 4) the

- If vaporizer does not run when the float switch is activated check 1) that there is
adequate sunlight to power the vaporizer, 2) the temperature is above 36_ F, 3) the
relay adjacent to the float switch (FS-1) is not faulty, 4) the vaporizer is not


- Flies can be controlled by installing a non-toxic fly strip near the access door inside
the waste tank and by adding wood chips more frequently. DO NOT add more than
is recommended.

- If the problem of excessive waste volume within the tank occurs, remove waste from
the front of the tank into a 30 gallon plastic garbage can. A bleach (store-bought
brand) and water solution of 1 ounce bleach to 1 gallon water should be added to
the garbage can. The waste should be saturated with the solution. The contents of
the garbage can should be mixed thoroughly with a stick and left overnight. The
contents should then be emptied into a nearby hole which is 2 feet deep and away
from the camp and water supplies. A vermiculture or enzyme additive can be
introduced to the compost pile to aid the composting process. Contact Camp
Supervisors or Bio-Sun, Inc. for further information.


- If the fan needs to be serviced, remove the ventilator from the top of the chimney.
The back wall of the chimney may not have to be removed. The fan is attached to
the stainless steel fan housing with two hex head bolts. The fan should be installed
so that the blades face up. This will draw the air upwards. If the fan is blowing air
into the tank simply reverse the wires in the control panel. Check the air flow
direction by lighting a match near the toilet seat and observing the smoke. Re-
silicon the ventilator casing to the top of the chimney walls when finished.


- Odors can be controlled by adding wood chips or by making sure the fan speed
control is on full. DO NOT add more than is recommended.

(see Appendix, figure 16)
All electrical parts are guaranteed for a period of one year from the date of purchase. The
tank and fixture is guaranteed for a period of five years from the date of purchase.

For technical assistance or questions contact:

Bio-Sun Systems, Inc.
Allen White, Owner
RR #2 Box 134 A
Millerton, PA 16936
(800) 847-8840
(717) 537-2200
(717) 537-6200 fax

or current R.M.C. Camps Supervisors.