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Jefferson Community Center compost

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Finished composter for the Jefferson Community Center.

Background[edit]

Our team worked with the Westside Community Improvement Association (WCIA) during the 2012 Spring semester at Humboldt State University for the Appropriate Technology course. Our project site is at the Jefferson School located on 1000 B St. in Eureka, CA. The people of WCIA would like a large composting system to handle all of their green yard waste. This waste will include all grass clippings, waste from the community gardens, and waste from pruning shrubs and trees. To become more sustainable, they would like to process their waste on site instead of their current plan to transport it over to Wes Green landscaping in Arcata, CA. We hope that this large scale composting system will be a viable option for their waste issues long into the future.

Problem statement[edit]

The objective of this project is to build a compost system for the WCIA that will handle their green waste materials, as well as provide a nutrient source for their on site community gardens.

Literature Review[edit]

This is a review of the available literature about how composting works including the different methods that can be used.

What is composting?[edit]

Composting is the process of decomposing organic materials into a natural humus (finished compost) used to enrich the soils used for farming, residential gardening, and large scale recycling. Compost benefits the garden in many ways. It contains bacteria that create natural antibiotics which protect the plants and helps them grow. Compost also provides nutrients and helps control the pH of the soil.[1]

Types of Composting methods[edit]

  • Indore Method- You would first spread a layer of brush on the ground and then build up the compost in layers. It becomes a compost heap with layers of green material, manure, straw and limestone. This is important because then the materials are evenly distributed throughout the compost.
    • It is also important for producing enough heat to kill weed seeds and any disease-producing fungi. The materials used should be in an area at least a 4 or 5 square feet by 5 feet high.
  • Fourteen-Day Composting: The Fast Method- The key to this method is grinding or shredding all of your materials which has these effects on the compost pile:
    • Surface area for microorganisms to thrive greatly increases
    • Aeration and moisture control are improved
    • Makes turning the heap easier

It is turned after 3 days and then continuously at 2 or 3 day intervals until the heap is decomposed.

  • Anaerobic Composting- It is composting without the use of air. The main benefit is not having to turn the compost. One disadvantage to turning the compost is oxidation, which destroys organic nitrogen. A major downside to anaerobic composing is the time processing, it is much slower.[2]
    • For Ex: By using a plastic cover or an anaerobic digester.
  • Sheet Composting- This is one of the two main techniques for composting sheet and heap (Indore Method). It means putting manure and green organic matter onto the soil directly and letting it decompose for a few months. This method puts a lot more nutrients directly in to the soil and not in the heap.
  • The Earthworm Method- This process uses earthworms to decompose the organic material. They help produce high quality compost.[3]

Silo Composting[edit]

  • This system is a hot, fast system that requires little to no more attention than regular heap composting. The system deals with large amounts of material in a short amount of time. The silos can be found at local nurseries and are usually made out of plastic. The silos can also be constructed out of recycled pallets and wood. An average silo contains one bin and all the decomposition occurs in the one bin. For a silo system a 50% green and 50% brown is best and is not turned. The compost could be ready between 6 months and a year. The silo bins usually have a door at the bottom for easy access to the compost. They are good for composting if you have a small labor force, and can be small enough to put about almost anywhere. [4]
    • Pros to this system are that pallets can be found for free, they have a large capacity and they reduce waste or wood burning.
      • Good for small areas, low labor, and cheap.
    • Cons are that pallets can be broken and they can look unattractive (but can be good looking).
      • Silos take longer to decompose materials than a three-bin system.

[5]

Criteria constraints Our weight (0-10)
Durability One year guarantee but it should last longer. 7
Aesthetics Blends nicely with the future landscape. 8
Cost Keep it under $200. 5
Easy to use Includes instructions and shows processing time (less than half an hour per week). 10
Location Must not be placed in an area that could be used for gardens. Must be centralized for easy access from kitchen, and garden areas. 6
Size Must be able to contain all green waste produced on site. 9
Safety Must be able to function properly without possible injury to users. 10
Educational value must be able to provide an understanding of the functionality and use of the device, within a ten minute viewing span 9

Costs[edit]

This is our initial budget proposal we were able to get most of our materials donated.

Quantity Material Retail Cost Our Cost
8 Pallets Free Free
2 2X6X8 Stud 8.99 Donated
3 Trim Board 3/4X1X8 11.99 Donated
4 Board 1X4X6 8.49 Donated
5 Board 1X8X6 12.99 Donated
2 1X12X6 17.99 Donated
5 Board 1X6X6 17.99 Donated
7 Board stud 2X3X8 6.49 Donated
64 ft. Hardware Cloth 4.29/ft. Donated
1-5lb. box Deck Screws #10X4in. 8.79 8.79
8 4X7/8 Corner bracket 2.99 23.92
5 1/2"X4'X4' Plywood 27.99 Donated
1 Gallon Primer 19..99 19.99
16 Angle Framing brackets 0.26 4.16
1 box Deck screws #8/3in. 4.74 4.74
1 box Stainless screws #10/1in. 7.00 7.00
1 box Stainless screws #10/1.25in 6.41 6.41
2 Handles 1.60 3.20
2 Swivel hasps 3.94 7.88
1 box Screw eye 1.10 1.10
1 Spring snap 3.35 3.35
4 Mending brace 0.83 3.35
1 2X3 Sheet plexi-glass 29.99 29.99

Proposed time line[edit]

Date Task to be accomplished
3/02/12 Calculations:
  • Current area mowed
  • Future area to be mowed
  • Verify volume values
  • Spread sheet for bin fill values
3/09/12 Prepare presentation for board meeting
3/13/12 Board meeting presentation
3/16/12 Start construction
3/23/12 Start signage design

Design[edit]

We have designed a one bin compost system with a lid in order to facilitate a hot fast composting process. The material is added to the bin and is static until the compost is ready. The first step was too wrap the pallets in a wire mesh using staples to hold in the material, keep out pests, and improve air flow. Then the pallets were placed upright and screwed together with brackets to a bottom pallet. We then sheeted out the plywood and wrapped it around the pallets. All the plywood was water treated and primed. Support blocks were put behind the plywood to hold the wood in place. We designed the bin to receive extra light and heat by having a clear Plexiglas lid. To improve the airflow of the bin we drilled four holes on each side of the bin. The front of the bin was designed to allow for the user to have enough room to shovel the compost without it being to tight. The top half of the front is plywood which supports a baffle which will hopefully keep materials away from the door making collection easier. The door was installed using hinges and includes an eye hook with a carabiner and chain to keep it up while in use. The lid was installed using hinges and can be supported up with a piece of wood. The plexiglass lid is framed in wood giving it support and durability.


Gallery[edit]

See Also[edit]

Special thanks to[edit]

  • Heidi Benzonelli and the Westside Community Improvement Association
  • Jack Rieke and Shafer's Ace Hardware
  • Buzz Rieman
  • Tim McLendon
  • Greg Pitch

References[edit]

  1. Smith, Kelley. How to Build, Maintain, and Use a Compost System. 2011. <http://books.google.com/books?id=hAQ60w2soC4C&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false>
  2. Lawrence K. Wang. Joo-Hwa Tay, Stephen Tiong Lee Tay. Environmental Bioengineering. Humana Press.2010.<http://books.google.com/ books?id=jGiQSjXQgTcC&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false>
  3. Organic Gardening and Farming Magazine. The Complete Book of Composting. Rodale Books, Inc. Emmaus, Penna. November. 1971.
  4. Seattle Public Utilities. Wood and Wire Stationary 3-Bin. The natural Soil Building Program <http://www.seattletilth.org/learn/resources-1/compost/compost>
  5. Klickitat County Solid Waste. Chosing a Compost System. Underwood Conservation District and the Washington State Department of Ecology Sustainability group. 2005.