Saturday, October 17, 2015

Closing the Loop on Food Waste: Food to Compost to Food

by John Chorlton, Verde Valley School

What we did

At the Verde Valley School Environmental Stewardship is ingrained in daily life. Through the Mission Statement and through actions undertaken by the whole community, since its inception in 1948, it is a living piece of the VVS lifestyle. One of our efforts was to close the loop on food waste, composting it along with horse manure from the equine program so it could go back on the garden. This is tricky because the Department of Health has regulations for composting to ensure pathogens aren’t passed on to students.

Each year, VVS produces about 2500 pounds of high-grade compost that helps our school garden to flourish. The value of the compost is approximately $600 a year. The value of not having the waste hauled away by waste removal services is about $3400 a year. Since 2011, VVS has utilized 100% of the compost produced.

How does it work

Capture food waste: After a student finishes his or her meal in the dining hall, they bring their dishes to the dishwashing station. Before stacking their plate in the window, they pass the recycling bins and then the composting bin. Here they separate their waste before moving on with their day. The kitchen staff empty the compost bin into a larger container outside the dining hall after every meal. Recycling crews pick up the recyclables twice a week.

Within the kitchen, the staff carefully and thoughtfully prepare food for the community every day. Throughout the process they are dumping food waste into five gallon buckets. They also put vegetable scraps into another bin for the chickens and another for the vermicomposting bin. They store these bins in the walk-in cooler.

Take it to the compost pile: Each day a team of two students arrives with a golf cart and attaches the 50 gallon receptacle outside the dining hall to the back of the cart with bungee cord. The students grab the food scrap containers from the walk-in cooler and make their way up to the composting compound.

Since the Fall of 2011 students have managed the process of layering food waste with horse manure from the stables and yard waste from the landscaping crew. Twice a week the team records ambient temperature, core temperature, relative moisture, Ph Balance and (more recently) precipitation. All of this is stored in a shared document that can be accessed and entered into via a smartphone on site.

Track nature at work: The bins that hold the compost materials are moved from Active holding bins to Passive  periodically (though they are constantly in some part of decomposition process). After the batches, which are named after their start date, are stored for at least 365 days, the piles are sifted into Finished product. All the viable organic materials that are too big for the Finished bin are put into pit composting piles with excess landscaping materials. These pit composts are 7 feet wide by 50 feet long by an average of five feet deep.

Test it: Over the course of a year, VVS produces about 2500 pounds of finished compost. A sample of this material is sent to Food Safety Net Services in Phoenix for testing. This is done to comply with state standards that allow us to move the compost product into the community garden.

Put it on the garden: Once in the community garden, the garden crew blends the compost with the native soil according to the needs of the crop. Since the garden was built, food has been grown and sold at a local farmers market to help offset the costs of running the garden.

Let the garden go to seed: Michael Spielman, who runs the garden, has created a seed bank comprised of heirloom, native and organic products. After the first crops were grown, seeds were harvested and added to the seed bank. During 2014 and 2015, many of the seeds were harvested from our original planting. Michael has seen a decrease in water consumption and increased heartiness after the first year as the next generation of plants adjust to the climate and soils. There has also been some wonderful cross-pollinations that are bringing unique and delicious produce to our community.

Plan meals around available produce: The garden crew and kitchen staff have begun planting and meal planning based on the crop production. Now the food being prepared for our community follow this path:
  • produce we have grown from our own seed,
  • is harvested by staff and students and then
  • is walked to the kitchen for preparation
  • to be served as a delicious, nutritious meal.

When a plate is cleared after a meal the cycle is renewed.

What we learned

Throughout the process there have been so many lessons learned. From planning policy, process and procedure to designing and building the systems, to implementation, everyone involved were forced to really think through how everything works together.

  • Defining how much food waste we produce in a year and what to do with it
  • Defining best practices for composting such large quantities
  • Defining how we manage composting process with students?
  • Learning how to interface with the state of AZ to get certified and then following through
  • Create and define protocols
  • Learning annual rhythms
  • Refining techniques through trial and error.
  • Communicating with the gardeners and getting timing and delivery of final product to the garden.
  • There were so many lessons learned in the construction process;
    • How to design and build a fence using as much re-purposed material as possible while still making a beautiful space
    • How deep to dig gopher wire trenching - and how not to get mad when they get in regardless of all the hard work.
    • How to work with many groups to achieve a common end goal


AZ regulations on composting -

Contact info for Phoenix x Food Safety Net lab -