Finding the Right Composter to Suit Our Company’s Needs
A lot of time was spent researching what type of container we wanted to use for composting the dog waste that Pet Poo Skiddoo collects. We knew we wanted to use an in-vessel composting method (meaning in an enclosed environment) rather than an outdoor static pile to ensure that odors are kept to a minimum – a main concern as you can imagine since we are dealing with fecal matter. There are many other benefits to using an in-vessel system such as it saves space, reduces labor, and offers valuable control over the temperature, moisture levels, and airflow.
The issue we found while shopping around is that there seemed to be a large gap in the compost market. We found small in-vessel units for sale that were meant for residential use, only large enough to handle a single family’s food scraps, and then the industrial scale in-vessel composters that are meant for high volumes, requiring thousands of pounds of organic material daily.
Luckily we found an ideal solution – the Earth Cube, designed by Green Mountain Technologies, a commercial composting company based in Bainbridge Island, WA. The Earth Cube is a 275 gallon structure made from a repurposed IBC (Intermediate Bulk Container), far too much capacity for single home use and geared more towards community sharing in local neighborhoods and gardens; Of course, it’s also the perfect capacity for a small company to start their composting journey.
Purchasing Our First Earth Cube
Our first prefabricated Earth Cube was purchased back in November 2017, which included a built-in divider panel. This way we can fill half of the cube at a time while the other side has time to “cook” before being emptied. The container is relatively easy to move – while empty, the Earth Cube only weighs 200 lbs and can be lifted by two people (moving straps help a lot).
We started with adding small amounts of waste (up to 25 lbs) on a daily basis to one side of the divider for a 4 week period, making sure the pile heats up to at least 135 degrees midway through. The following 4 week period was for exclusively mixing, allowing the other empty side to start receiving new waste. The nice thing is that the divider panel allows you to start experimenting with your composting recipes and see what works before having to purchase additional Earth Cubes for alternating batches.
It didn’t take long to realize it wasn’t until the pile reached a certain volume that it would start to heat up – an estimated minimum of 300 lbs of dog waste stacked to at least 3 feet tall is necessary for the pile to start cooking (which is why it’s not really plausible for homeowners to compost the small amounts of waste their dogs put out on a regular basis).
When we’re ready to empty the vessel, the contents are transferred to a more open, cedar-based (handmade) structure where the cooked pile can cure for an additional 1-3 months. This is where the (now) humus is in direct contact with a dirt floor where beneficial fungi and insects can seep into the pile and enrich its contents.
Building Our Second Earth Cube
We ended up building the second Earth Cube in April 2019. Green Mountain Technologies also offers a DIY kit that includes crucial key components, and a detailed manual with step-by-step instructions accompanied by photos. It’s a more economical option, although requires certain tools and knowledge in construction to pull off. You will need to purchase a food-grade IBC separately, making sure its measurements closely match what the manual recommends. The cladding (material for the outer covering) will also need to be purchased on your own, although the cladding can be altered slightly to create a different look.
With two Earth Cubes in place, we are now able to compost up to 1500 lbs of dog waste per month. We attend to the vessels at least every 2-3 days in order to mix, aerate, and water.
How the Earth Cube Works
The general idea of the Earth Cube is to protect its contents from the outside environment while still letting air come in and moisture go out. The natural opening at the bottom of the IBC, designed to drain out liquids, brings in air while a perforated pipe built down the center is used to disperse that air throughout the interior. There is also a filtered opening constructed at the top to allow additional air circulation while keeping the odor’s spread to a minimum.
The most substantial alteration to the IBC is the hinged door that serves as the access port. It’s a clever way to quickly access and mix your material with ease while still maintaining a seal once the door is closed. A wear bar lines the bottom of the port allowing you to lean a pitchfork on for leverage, lessening the physical exertion needed to mix the pile.
Benefits of the Earth Cube
A big benefit to in-vessel composting is the ease of controlling the moisture levels. Since most static piles and windrow setups are situated outside and exposed to all weather conditions, much of its inputted moisture comes from rainfall, which can be hard to measure. The rainwater then slowly seeps to the bottom of the pile and into the ground – an output that can’t be measured either. But with the IBC container, you’re keeping track of all of the water that goes both in and out.
Whatever water you add, whether from rain barrels or other sources, can be measured and evenly mixed in to ensure all of the material is being wettend as needed. A healthy compost should be slowly draining every day – the brown liquid that drains out of the bottom can be monitored and captured into a container.
We actually use an oil drain pan to capture this liquid that was purchased from a company called Garage Boss. The 3.5” tall pan can hold up to 12.5 quarts and includes a funnel attachment that can be placed directly under the IBC’s drain when the Earth Cube is situated on top of a standard wood pallet. This liquid can either be placed back into the vessel through the access port or transported somewhere to be filtered and sanitized.
All in all, we’ve been quite satisfied with using the Earth Cube. It’s relatively small and compact, but yet can handle the hundreds of pounds of pet waste we need to offload on a weekly basis. We’ll definitely be building a few more as the amount of dog waste we collect increases.