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Background

Our team will be working with the Westside Community Improvement Association (WCIA) during the 2012 spring semester at Humboldt State University for the Appropriate Technology course. Our project site will be 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

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

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

What is composting?

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

  • 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]

Three-Bin System

  • This system is a hot, fast system that requires a little more attention than regular heap composting. The system deals with large amounts of material in a short amount of time. It contains three separate bins, which separate the materials based on their decomposed stage. For a three-bin system a 50% green and 50% brown is best and is turned every 7 to 14 days. The compost could be ready between 3 and 6 weeks.[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.
    • Some cons are that pallets can be broken and they can look unattractive (but can be good looking).[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

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
6 Corrugated Roofing 10.00 60.00
5 1/2"X4'X4' Plywood 27.99 Donated

Proposed time line

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

We have designed a three bin covered compost system in order to facilitate a hot fast composting process. New material is added to the first bin. After a week, half of the material from the first bin is moved to the second bin, then new material is added to the first bin. After another week, half of the material from the second bin is moved to the third bin, and half of the material from the first bin is moved to the second bin, and more material is added to the first. The boards in front of each can be removed for moving material between bins. Jefferson community 3-bin composter image.jpg

Gallery

References

Template:Reflist

  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.
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