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CommunityDesign

How We Respond When Nature Calls

By Nicky Rhodes and Kelsey McWilliamsJuly 31, 2023October 30th, 2023No Comments

The Case for Waste

There are few things we interact with more on a daily basis than toilets. Sanitation is central to community infrastructure; yet, most people are unaware of the high-value nutrients stored within our urine and feces. Circular sanitation – the process of transforming human waste into resources such as compost, heat, electricity, water, or animal feed – offers a realistic alternative to wasting our waste. Compost toilets like the one described in this article not only return our waste back to nature, but provide an opportunity to create beautiful, beneficial, and uplifting community spaces that inspire users to understand their waste in a new way: as a high-value resource. 
Developed in partnership with circular sanitation consultancy Point of Shift, Stonehedge Holistic Learning Center, and the Lehigh Valley Natural Builders Guild, this project is a prototype for a DIY, low-cost compost toilet made primarily with reused materials. Since its completion in summer 2021, we have monitored how the structure and compost process have fared. After some trial and error, we are eager to share our observations to help others connect with their environment and strengthen their communities through this small-scale renewable resource production. 

Getting Started

Nestled among verdant rolling hills and former coal towns of the Lehigh Valley in Northeast Pennsylvania, Stonehedge Holistic Learning Center aims to inspire, educate, and cultivate community through art, permaculture, and connections with nature. Stonehedge serves as a living laboratory for alternative and natural building projects. The space hosts a wood-fired cob oven, a timber frame shelter, and an on-site Earthship greenhouse that recycles the property’s greywater; and it also supports a nearby off-grid housing community. 
While visiting Stonehedge for a yoga retreat in July 2020, Kelsey McWilliams, CEO of Point of Shift, noticed that the presence of chemical porta-potties felt misaligned with Stonehedge’s commitment to promoting sustainable practices. Kelsey began conversations with Stonehedge director Tom Moroz and Nicky Rhodes, the Vice Chair of the Lehigh Valley Natural Builders Guild. The Guild’s mission is to grow and support a network of skilled natural builders in the Northeastern Pennsylvania region. These initial discussions grew into a flourishing vision for an integrated circular sanitation system, beginning with a single compost toilet. Stonehedge’s first in-person festival since the pandemic began was set for September 2020, and provided the perfect backdrop to begin realizing our vision. We framed this design as a prototype that DIYers could replicate and adapt for their own needs and the construction process as a tool for hands-on community empowerment.

Design & Construction

Members of the Lehigh Valley Natural Builders Guild and Point of Shift designed the prototype to be constructed by volunteers with little construction experience, within a short timeframe, and on a tight budget; therefore, simplicity was key. We determined that an A-frame structure would be easiest to construct while best honoring the site’s historic farm buildings. By resting the frame on concrete blocks rather than permanent footers, we provided the structure with a light, easily reversible touch on the ground.
In addition to budget and environmental concerns, we sought to reconceptualize “waste” as a resource and use reclaimed and salvaged materials wherever possible. Our design had to be flexible because we did not know the specific building materials we would eventually be able to access. We ultimately used second hand materials for roughly 80-90% of the structure, including the compost barrels. We purchased hardware, several pieces of dimensional lumber, and a few sheets of plywood sheathing. Costs for new materials totalled approximately $300, and the duration of the volunteer-led construction was six days. We hope to reduce both in future iterations.
While the compost toilet is utilitarian in nature, our main design priority was to fundamentally elevate the outhouse experience. Inspired by the ancient Japanese practice of Shou Sugi Ban [Ed: traditionally known as Yakisugi], we charred the wooden facade with a propane torch. This acts as a natural weather and rot-resistant treatment, while the deep black color reflects the rawness of the surrounding landscape. The darkness of the toilet’s exterior also contrasts with the interior’s lightness and airiness provided by the reclaimed translucent polycarbonate panels at head height on the sidewalls. Natural ventilation keeps users cool and odors manageable through openings covered with insect netting at each end of the roofline. While our original plans called for a plywood door with decorative diagonal charred wood applied on top, we ran out of salvaged materials and instead opted for hanging fabric which can be secured shut. We landscaped the waiting area in front of the toilet with plantings, sculptures, and benches made from reclaimed lumber, all designed to maintain privacy and create a holistically beautiful experience for those using the toilet. 
Images from base plans of the composting toilet,
which are available to download Here.

DIY Compost Systems 

Sanitation regulations in the United States vary state-to-state. In Pennsylvania, compost toilets or other approved circular technology systems can be implemented on properties that already have a septic tank or sewer connection. Similar to food scraps, composting human waste requires a combination of nitrogen and carbon-based materials to support the growth of microbes that assist in breaking down the organic waste. 
A single 55-gallon repurposed plastic barrel underneath the toilet seat captures both liquid and solid waste. These types of barrels can be easily sourced or bought second hand via Facebook Marketplace, Craigslist, etc. An initial layer of straw, dirt, and leaves – all sourced from around Stonehedge – is laid at the bottom of the barrel and creates air pockets in the waste pile. This helps aerate decomposing matter and accelerate the composting process, while also absorbing liquid.
After using the toilet, people are instructed to add a handful of sawdust to the barrel, a byproduct from the Natural Builders Guild’s chainsaw milling workshops. This acts as the “bulking agent” – an additive used to maintain proper levels of moisture and carbon-nitrogen balance, and minimize foul smells. Once the barrel is approximately 75% full, it is removed from the toilet and replaced with a clean barrel. As our toilet was built toward the end of Stonehedge’s festival season, it took seven months for our barrel to be filled. The filled barrel is then relocated to a less-trafficked location on the grounds, where a layer of food compost, dirt, and leaves are added on top of the waste, helping jumpstart the composting process. The barrel is then sealed with a lid containing small holes for aeration, which are covered with a screen to prevent flies from entering the barrel. The barrel remains sealed for approximately one year, when the compost is ready for land application.
The finished compost looks like dark soil, similar to food compost. Once the compost is removed, the barrel is cleaned with water and again ready for use in the toilet. Various states regulate where human waste compost may be used. Generally, it is best suited for fruit trees (prior to harvesting season) and non-edible plants. This provides an extra layer of protection against consuming any remaining miniscule pathogens in the compost. 

Takeaways 

As an experiment to advance DIY circular sanitation at Stonehedge and beyond, we monitored the design/build and long-term compost processes to better inform our future toilet projects. 
  1. Perhaps the most important indicator of the project’s success is the toilet’s consistently sweet and pleasant smell, a sign of a well balanced combination of carbon, nitrogen, and moisture in the compost pile. Were the pile to smell sickly sweet or like sulfuric acid, that is a likely sign that it has become anaerobic, meaning too much liquid in the pile is preventing oxygen-loving microbes from thriving and breaking down waste. This could be avoided by adding more bulking material (like sawdust) after every use.  Occasionally adding coffee grounds to the pile helped maintain the inoffensive odor. 
  2. Flies are naturally attracted to decaying waste, but we substantially reduced their presence by keeping the compost barrel area well-ventilated and isolated with insect netting, and requesting users close the toilet lid between use. Bulking material decreases the moisture in the barrel and thus additionally helps with reducing flies. 
  3. We discovered that at 75% full, the compost bucket was too heavy for a single individual to transport by themselves, requiring two people with a dolly. We pivoted to using heavy-duty trash cans with built-in wheels, allowing for easier transport to the long-term compost processing site.
  4. After the summer festival season at Stonehedge, we added a urine diverter to the toilet seat, which redirects liquid waste into separate collection jugs. After being sealed and allowed to self-pasteurize for 30 days, the urine is diluted with ten parts water and applied to the land. By adding this urine diverting system, the compost barrels require less bulking agent and are easier to relocate during peak summer usage. 
  5. While using primarily salvaged materials lowered the project’s carbon footprint and overall material cost, the inconsistency in dimension and quality of materials we sourced was a challenge in design and construction. We had to discard warped lumber several times. We also had to modify building plans on-the-fly in order to accommodate non-standard materials. In the future, we would consider purchasing new dimensional lumber for the structure and using salvaged materials for the sheathing and interiors.
  6. Our approach to charring the wood facade differed much from the traditional Shou Sugi Ban method, which typically uses cedar planks. Charring salvaged wood proved challenging as it was difficult to determine if there were any impurities that could be hazardous to burn. From a durability perspective, the charred wood facade has shown no signs of decay, withstanding a harsh winter and many rain storms. Additional monitoring is required to understand the full durability of the charred wood facade and base frame.

Looking Ahead 

The compost toilet project is a successful first step in the larger vision to transform all organic waste generated at Stonehedge – both human waste and food scraps – into usable fertilizer. Equipped with all that we have learned through this process, we plan to design and build more compost toilets to support a growing glamping and festival infrastructure at Stonehedge, and experiment with a greater variety of lightweight materials and low-carbon construction techniques. Another project that will support this vision is renovating a derelict mobile home into a rainwater-powered bathhouse and central waste treatment center, where collected human waste from compost toilets will be further broken down through composting systems. Additionally, we hope to host construction and composting workshops facilitated through the Lehigh Valley Natural Builders Guild and Point of Shift, to teach others how to build their own low-cost compost toilets. 
If you’re interested in building your own compost toilet using the plans we’ve developed, you can download the base plans from www.nicky-rhodes.com/toilet.html. These plans are dynamic and intended to evolve through collaborative expertise. If you have ideas for ways to make the process cheaper, simpler, more sustainable, or more beautiful, please reach out to nickyarhodes@gmail.com. If you are interested in implementing your own composting toilet or unique circular sanitation system, contact Kelsey at www.pointofshift.com
Stonehedge Holistic Learning Center is actively seeking investment to support the expansion of its sustainable glamping operations. Learn more at www.mainvest.com/b/stonehedge-pbc-tamaqua. If you’re local to the Lehigh Valley, you can get involved with the Lehigh Valley Natural Builders Guild by visiting our website at naturalbuildersguild.org. The Guild frequently hosts educational workshops and monthly meetups, and we are always looking to expand our community. 

 

 

Nicky Rhodes is an architectural designer committed to innovative practices of sustainability. He served as Vice Chair of the Lehigh Valley Natural Builders Guild through Summer 2022, and is currently studying architecture at the Harvard University Graduate School of Design. 
www.nicky-rhodes.com 
Kelsey McWilliams is an environmental engineer committed to making bathrooms more beautiful and sustainable. Kelsey has designed and implemented circular sanitation systems in the United States, India, and Kenya. Kelsey founded Point of Shift in 2020 to help accelerate the implementation of circular sanitation solutions for communities across the globe. 
www.pointofshift.com

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