organic flapjacks final documet

The Barrel O’ Fun Worm Bin Organic Flapjacks

The Barrel O’ Fun

Designed by:

Engineering 215: Introduction to Design, Spring 2011

Project for Locally Delicious and Lunchbox Envy

6 May 2011


Table of Contents

1 Problem Formulation.............................................................................................................................1

1.1 Introduction....................................................................................................................................1

1.2 Objective........................................................................................................................................1

2 Problem Analysis and Literature Review..............................................................................................1

2.1 Problem Analysis...........................................................................................................................1

2.2 Specifications and Considerations.................................................................................................1

2.2.1 Specifications.........................................................................................................................1

2.2.2 Considerations........................................................................................................................1

2.3 Criteria and Constraints.................................................................................................................2

2.4 Literature Review...........................................................................................................................2

2.4.1 Vermicomposting...................................................................................................................2

2.4.1.1 Three Outcomes of Vermicomposting...............................................................................2

2.4.1.2 Examples of Vermicomposting..........................................................................................3

2.4.1.3 Types of Vermicomposting................................................................................................3

2.4.1.3.1 Micro Vermicomposting..............................................................................................3

2.4.1.3.2 Macro Vermicomposting.............................................................................................4

2.4.1.4 Compost Materials.............................................................................................................4

2.4.2 Worms....................................................................................................................................4

2.4.2.1 Species...............................................................................................................................4

2.4.2.2 Environmental Conditions.................................................................................................5

2.4.2.2.1 Oxygen.........................................................................................................................5

2.4.2.2.2 Moisture.......................................................................................................................5

2.4.2.2.3 Temperature.................................................................................................................5

2.4.2.3 Basic Biology.....................................................................................................................5

2.4.2.3.1 Nutrition.......................................................................................................................5

2.4.2.3.2 Reproduction................................................................................................................5

2.4.2.3.3 Behavior.......................................................................................................................6

2.4.3 Materials................................................................................................................................6

2.4.3.1 Safety.................................................................................................................................6

2.4.3.1.1 Toxicity........................................................................................................................6

2.4.3.2 Durability & Strength of Materials....................................................................................6

2.4.3.2.1 Ideal Long Term Materials..........................................................................................7


2.4.3.2.1.1 Wood.....................................................................................................................7

2.4.3.2.1.2 Plastic....................................................................................................................7

2.4.3.2.2 Environmental Stresses................................................................................................7

2.4.4 Mechanics of Composting.....................................................................................................7

2.4.4.1 Internal Process..................................................................................................................7

2.4.4.1.1 Types............................................................................................................................7

2.4.4.1.1.1 Open Loop............................................................................................................7

2.4.4.1.1.2 Flow Through........................................................................................................8

2.4.4.1.1.3 Bins.......................................................................................................................8

2.4.4.1.1.4 Stackable...............................................................................................................8

2.4.4.1.1.5 Closed Loop..........................................................................................................8

2.4.4.1.1.6 Beds.......................................................................................................................8

2.4.4.1.2 Examples......................................................................................................................8

2.4.4.2 Input...................................................................................................................................9

2.4.4.3 Capacity.............................................................................................................................9

3 Search for Alternative Solutions..........................................................................................................10

3.1 Introduction..................................................................................................................................10

3.2 Brainstorming..............................................................................................................................10

3.3 Alternative Solutions...................................................................................................................10

3.3.1 Barrel O’ Fun.......................................................................................................................10

3.3.2 Drawers O’ Worms..............................................................................................................11

3.3.3 Cin-Bin.................................................................................................................................12

3.3.4 The Worm Tower.................................................................................................................13

3.3.5 The Compost Chute.............................................................................................................14

3.3.6 The Worm Wheel.................................................................................................................15

3.3.7 The Circle of Life.................................................................................................................16

4 Final Decision......................................................................................................................................17

4.1 Criteria.........................................................................................................................................17

4.2 Alternative Solutions...................................................................................................................18

4.3 Decision Process..........................................................................................................................18

4.4 Final Decision..............................................................................................................................19

5 Specification of Solution......................................................................................................................19

5.1 Introduction..................................................................................................................................19


5.2 Solution Description....................................................................................................................19

5.3 Cost Analysis...............................................................................................................................21

5.3.1 Design..................................................................................................................................22

5.3.2 Implementation....................................................................................................................22

5.3.3 Maintenance.........................................................................................................................23

5.4 Implementation Instructions........................................................................................................23

5.5 Prototype Performance.................................................................................................................31

6 Appendices...........................................................................................................................................31

6.1 Appendix A: References..............................................................................................................31

6.2 Appendix B: Brainstorming Notes...............................................................................................32


Table of FiguresFigure 1-1: A Black Box Diagram in which a problem or issue enters one side of the black box, and it exits as a solution...........................................................................................................................................1Figure 2-1: An example picture of vermicomposting in action (http://www.flickr.com/photos/68632374@N00/4050063071)....................................................................3Figure 2-2: Eisenia fetida, the "red wiggler", is the most common worm used in composting (http://www.woodwormfarms.com/pics/worms/redworms2.jpg)..................................................................4Figure 2-3: Plan for a worm bin made out of wood (http://stopwaste.org/images/2person.gif)....................6Figure 2-4: A bin system built with wood materials (http://www.worm-bins.net/)......................................8Figure 2-5: A bin system built with plastic materials (http://kitsap.wsu.edu/hort/worm_bin.htm)...............9Figure 2-6: An example of a stackable vermicomposting bin (http://i1043.photobucket.com/albums/b435/WorldTreeGardening/Available%20Products%20%20Services%20and%20Concepts/Compost%20bin%20designs/worm-composter-diagram.jpg)......9Figure 3-1: A drawing of the "Barrel O' Fun" (Drawn by Paul Johnston)..................................................11Figure 3-2: A drawing of the "Drawers O' Worms" (Drawn by Paul Johnston).........................................12Figure 3-3: A sketch of 3 Cin-Bins arranged in series. (Drawing by Paul Sereno).....................................13Figure 3-4: The Worm Tower, with overhead view. (Drawing by Paul Sereno)........................................14Figure 3-5: The Compost Chute, an alternative solution designed by Max Hullman.................................15Figure 3-6: The Worm Wheel, an alternative solution designed by Max Hullman.....................................16Figure 3-7: The Circle of Life a vermicomposting solution by Max Hullman............................................17Figure 5-1: An AutoCAD drawing of three basic views of the Barrel O' Fun (drawn by Paul Johnston). .20Figure 5-2: An AutoCAD drawing of the spigot and “nest barrel” (by Paul Sereno).................................20Figure 5-3: An AutoCAD diagram of the PVC frame for the tarp (Drawn by Paul Johnston)...................21Figure 5-4: The design cost, in hours, spent on each phase of the design process......................................22Figure 5-5: The 55 gallon barrel cut in half. (Photo by Paul Sereno)..........................................................23Figure 5-6: The removal of the end will create a "nest" barrel. (Photo by Paul Sereno)............................24Figure 5-7: The barrels are connected and overlap by 5". (Photo by Paul Sereno).....................................24Figure 5-8: The spigot, installed. (Photo by Paul Sereno)...........................................................................25Figure 5-9: 1/4" drain holes are drilled into the dividing wall. (Photo by Paul Sereno).............................25Figure 5-10: Silicone caulk is used to glue the gutter strainer over the entrance to the spigot. (Photo by Paul Sereno).................................................................................................................................................26Figure 5-11: The outer connection is caulked to prevent leaking. (Photo by Paul Sereno)........................27Figure 5-12: The pallets and the cinder blocks set in place. (Photo by Paul Johnston)...............................27Figure 5-13: The trough is cut into the pallet. (Photo by Paul Johnston)....................................................28Figure 5-14: The barrel is placed in the trough. (Photo by Paul Johnston).................................................28Figure 5-15: The T-jointed crossbars that span the barrel. (Photo by Paul Sereno)....................................29Figure 5-16: A 1/4" notch is cut in each end of the PVC. (Photo by Paul Sereno).....................................29Figure 5-17: The elbow piece is inserted, which will tent the plastic sheet. (Photo by Paul Sereno).........30Figure 5-18: Worms are added to the bin. (Photo by Paul Johnston)..........................................................30Figure 5-19: The sheet is bungeed to the corners of the pallet, and adjusted for a snug fit. (Photo by Paul Sereno).........................................................................................................................................................31Figure 6-1: Brainstorming Notes on March 1, 2011....................................................................................33Figure 6-2: Brainstorming Notes on March 1, 2011....................................................................................33Figure 6-3: Brainstorming Notes on March 3, 2011....................................................................................34


Figure 6-4: Brainstorming Notes on March 3, 2011....................................................................................34Figure 6-5 Brainstorm of possible designs on March 11, 2011...................................................................35Figure 6-6 Brainstorm of possible issues on March 11, 2011.....................................................................35

Table of TablesTable 5-1: Breakdown of material costs for the Barrel O’ Fun worm bin...................................................22Table 5-2: Breakdown of time cost for maintenance...................................................................................23


1 Problem Formulation

1.1 IntroductionIn Section I of the design process, the problem is formulated by creating an objective statement and a “Black Box” diagram.

1.2 ObjectiveThe objective of the project is to create a composting worm bin for a Jacoby Creek Charter School that will last long term. The worm bin will teach children hands-on how “vermicomposting” works.

Figure 1-1: A Black Box Diagram in which a problem or issue enters one side of the black box, and it exits as a solution

2 Problem Analysis and Literature Review

2.1 Problem AnalysisSection II Problem Analysis provides information and an analysis of the criteria for the worm bin, and overviews the specifications and considerations of the project.

2.2 Specifications and ConsiderationsThe specifications and considerations are requirements and thoughts for the project based on research and the client criteria.

2.2.1 SpecificationsSpecifications are the minimum requirements for the project that must be followed in the designing of the project. The specifications are:

Able to be used by ages 8 to 12 (fourth to eighth grade) Must contain educational content Must be professional and aesthetically pleasing Must use organic or sustainable materials

2.2.2 ConsiderationsConsiderations are thoughts for the project and are not necessarily needed in the designing process. The considerations are:

Location: Built in Arcata/outdoors Usage/production Instructions to be used by children 8-12 years old

OUTPUTJacoby Creek Charter School

with a way to educate children about composting

and vermicomposting through a long-term worm bin.

INPUTJacoby Creek Charter

School without a way to educate children about

composting and vermicomposting

Black Box


2.3 Criteria and ConstraintsCriteria and constraints set up a way to distinguish the quality of alternative solutions for the project. The criteria and constraints are:Criteria Constraints

Safety Non-toxicPhysical Safety (edges, points…etc)

Cost Less than $375

Simplicity Low construction time from volunteersLow maintenance

Educational Conveys vermicomposting

Durability Lasts five or more years

Efficiency High output to time ratio

Scalable Easily scalable in size

Aesthetics Professional and aesthetically pleasing

2.4 Literature ReviewThe literature review is a collection of research that is about vermicomposting and vermiculture. It covers the basics of vermicomposting, the biology of worms, materials, and mechanics. All references are located in the appendix A.

2.4.1 VermicompostingVermicomposting is the process of having worms and other decomposer organisms provide usable natural fertilizer and more (Zorba 2010).

2.4.1.1 Three Outcomes of VermicompostingThere are three main outcomes from the process of vermicomposting, each providing environmental benefits and educational rewards to everyone involved. The outcomes of vermicomposting are the breeding of worms as bait, the use of the worm castings as a natural fertilizer in gardening, and the breakdown of leftover waste (Agaraw 2005).


Figure 2-2: An example picture of vermicomposting in action (http://www.flickr.com/photos/68632374@N00/4050063071)

2.4.1.2 Examples of VermicompostingThere are vast amounts of ways that vermicomposting can be executed. It depends greatly on the location and the temperature. Also, the designer must consider many conditions when creating a vermicomposting setup. Casual vermicomposting designs are usually set into small bins or boxes in the kitchen or outdoors, while more serious vermicomposting enthusiasts use pits, trenches, or large bins. Each method has its benefits and drawbacks, as each depends on many things including time and money (Agaraw 2005).

2.4.1.3 Types of VermicompostingVermicomposting has several variations in design and size. These variations are based upon the scale of the project.

2.4.1.3.1 Micro VermicompostingOne type of vermicomposting that is used in many homes is small-scale vermicomposting, or micro-vermicomposting. Usually built by the owners themselves, they are most often made out of old plastic containers, wood, Styrofoam, or metal containers. Bins should have holes poked in the sides to allow airflow, as well a hole at the bottom to allow a collection tray. Small bins types can be divided into three more categories: non-continuous, continuous vertical flow and continuous horizontal flow (Parthasarathy 2008).


2.4.1.3.2 Macro VermicompostingLarge-scale vermicomposting does not normally incorporate a physical bin, and usually consists of open rows of bedding for the worms to live in. Theoretically the worms can escape this system, in practice they stay due to the large abundance of organic matter. This is a very efficient method as the larger space offers the ability to have more worms and for waste to be decomposed in a shorter time (Parthasarathy 2008).

2.4.1.4 Compost MaterialsCompostable materials include most food wastes and many organic or biodegradable items. Some examples are vegetable peelings, fruit cores, teabags, and grain-based items. The materials to start off the bedding of a worm-bin can include shredded newspaper, cardboard, loam or black top soil, a mixture of sawdust, peat moss, shredded leaves, dead plants, ordinary soil, coir, and commercial worm bedding (Elcock 1995).

2.4.2 WormsThe worms used in vermicomposting are earthworms. Five different species of worms have been used for successful vermicomposting. The success of a worm bin depends on environmental factors as well as a basic understanding of worm biology.

2.4.2.1 SpeciesFive earthworm species have been well studied for the breakdown of organic wastes: E. fetida (red wiggler), D. veneta (earthworm), L. rubellus (red earthworm), E. eugeniae (African nightcrawler), and P. excavates (bark worm) (Bohlen 1996). The first three are more suited to a temperate climate, whereas the latter two are tropical species (Bohlen 1996). The red wiggler (Figure 2-3) is the most commonly used species, as it is most suited to the varied climates of the United States (Bohlen 1996). However, all species can be used equally well in most situations.

Figure 2-3: Eisenia fetida, the "red wiggler", is the most common worm used in composting (http://www.woodwormfarms.com/pics/worms/redworms2.jpg)


2.4.2.2 Environmental ConditionsThe success of a worm bin depends on several environmental factors including oxygen content, moisture, and temperature. If these factors are not met, productivity can slow or even come to a stop (Munroe 2005).

2.4.2.2.1 OxygenEarthworms can survive for long periods of time at low oxygen concentrations, up to ten percent of normal levels. However, they do move away from anaerobic conditions (Bohlen 1996).

2.4.2.2.2 MoistureDifferent species of earthworms exhibit different moisture requirements. The ranges of soil moisture required for different species range from 10-85%, with higher moistures preferred by most species (Bohlen 1996). Moisture contents of 75-80% have been found to optimum for growth and reproduction (Bohlen 1996). Many worm species are able to survive for several weeks in waterlogged soils, so the only adverse effects of high moisture are on the containing bin (Bohlen 1996). Moisture is controlled by adjusting the bin’s exposure to open air (Munroe 2005).

2.4.2.2.3 TemperatureThe temperature of the soil affects the growth, reproduction, and survival of earthworms. The optimum temperatures for worm development for most species range from 10-25°C (Bohlen 1996). E. fetida is able to survive at temperatures as low as 0°C and as high as 35°C, with offspring cocoons being able to survive freezing (Munroe 2005). If temperatures rise above 35°C, the worms cannot survive. Temperature is regulated by covering the bin during the winter, or controlling the amount of decomposing material (Munroe 2005).

2.4.2.3 Basic BiologyIt is important to have a basic understanding of worm biology, including nutrition, reproduction, and behavior in order to have a successful vermicomposting operation. Earthworms are segmented invertebrates, meaning they lack an internal skeleton. Their segments are used for movement (Bohlen 1996). They are bilaterally symmetrical and hermaphrodites.

2.4.2.3.1 NutritionEarthworms utilize organic matter for nutrition. Microorganisms in the alimentary canal break down this matter into usable nutrients. Earthworms also eat and then excrete fungi and bacteria. The fungi and bacteria then accelerate the breakdown of cellulose, increasing the amount of carbon and other nutrients in the soil (Aira et al. 2006). An established worm population can consume its own weight in food each day; however it is recommended that they be fed half their weight each day (Munroe 2005).

2.4.2.3.2 ReproductionEarthworms, after mating, produce cocoons. Each cocoon can give rise to several worms (Bohlen 1996). Theoretically, populations can double every 60 days, but this is often not achieved (Munroe 2005). This doubling rate is affected by a lack of knowledge about vermicomposting, resources, and poor preparation for winter on behalf of the vermicomposter (Munroe 2005).


2.4.2.3.3 BehaviorEarthworms can be grouped into three subcategories: epigeic, endogeic, and anecic (Werner 1990). These categories are founded in the behavioral ecology of the worms. Epigeic species live in the surface plant litter, endogeic worms burrow horizontally below the surface, and anecic worms build deep, permanent burrows (Werner 1990). Worms avoid exposure to light; this can be taken advantage of when harvesting the compost, as the worms will burrow into the lower levels to avoid the light (Munroe 2005).

2.4.3 MaterialsWhen constructing a worm bin, it is necessary to make sure that all materials gathered and used are not hazardous to the worm’s health. Hazardous materials can include lead, certain treated woods, and any other toxins that are put into materials. Materials such as rubber storage totes, galvanized tubs, wood, or plastic are sufficient materials for constructing a worm bin (Elcock 1995). Below is an example of a wooden worm bin (Figure 2-4).

Figure 2-4: Plan for a worm bin made out of wood (http://stopwaste.org/images/2person.gif)

2.4.3.1 SafetySafety is important for both the people using the worm bin, and the worms inhabiting it. If the materials used to build the worm bin are unsafe, it can cause the failure of a vermicomposting project.

2.4.3.1.1 ToxicityThe dangers of toxicity concerning worm bins generally affect only the worms and the plants that will be eventually grown in the compost. Factors that can affect toxicity are the materials the bin is made of and the input material for composting. Worms even make the compost safer for humans. "Earthworms stabilize organic residues and reduce pathogenic bacteria and other human pathogens" (Mycological Society of America, 2005).

2.4.3.2 Durability & Strength of MaterialsThe lifespan of a worm bin can range from one year to thirty years, as the materials used to build the worm bin can last through misuse, environmental conditions, and weathering. When properly designed, they are capable of handling the amount of compost that will build up in between the extraction times.


2.4.3.2.1 Ideal Long Term MaterialsMaterials that are ideal for a long-term worm bin include: woods such as CDX plywood, galvanized steel tubs, and some rubbers and plastics. CDX plywood is simply a thicker, compressed, untreated wood that is used for construction (CDX Plywood).

2.4.3.2.1.1 WoodWood has been used as a building material for thousands of years, and until late 20th century, was the most popular material for vermicomposting. Wood is popular due to its wide availability, and its customizable construction. The biggest challenge is preventing rotting from the high moisture levels of the worm bedding. Certain types of wood can distress worms; treated lumber and tannin-containing woods should be avoided (Parrish, 2010).

2.4.3.2.1.2 PlasticPlastic is another material, and is gaining popularity as a worm bin material. Plastic is much more environmentally durable than wood and is lighter, while still being widely available. Plastic is generally nontoxic, but certain types of plastic can be harmful to worms.

2.4.3.2.2 Environmental StressesEnvironmental stresses, such as moisture and temperature, can reduce the lifetime of a worm bin. Worm bins contain moist, wet soil. This can cause untreated woods to rot, while causing steel and iron to rust (Schlenker 1969). Rust is slightly toxic and can become harmful to the worms’ health. Only very high temperatures (such as 2,750 °F for iron) can affect metals, but wood can be affected by temperature. When temperatures rise, wood can become malleable, and can warp and bend (Schlenker 1969). Materials that cannot breath or let air flow through can affect the worms inside by poorly regulating the moisture level and temperature. Other possible stresses include corrosion, soiling, leaning damage, and atmospheric pollution such as acid rain (Lodge 1985).

2.4.4 Mechanics of CompostingThis section deals with the different composting methods, which affect the physical structure of the worm bin.

2.4.4.1 Internal ProcessThe internal process is how waste moves through the system. The waste is thoroughly decomposed so that it is viable for gardening. The internal processes vary based on the size and structure of the bin.

2.4.4.1.1 TypesThe main challenge in the construction of a worm bin is to make depositing and removing the food scraps as easy as possible (EZ Worm Composter, 2011). The waste also has to be entirely decomposed before removal; therefore it is necessary to find a way of separating different sections of the bin to ensure full decomposition. The two categories of vermicompost structures are open and closed loop systems. Each category additionally has many different possible designs.

2.4.4.1.1.1 Open LoopOpen loop designs involve a continuous cycle of decomposition, which means they require occasional monitoring and managing of the compost.


2.4.4.1.1.2 Flow ThroughThe flow through method involves a container with an opening at the bottom for removal of the compost, while keeping in mind that the worms will only occupy the top portion of the compost. Waste is deposited in the top and by the time it reaches the bottom the worms will have already converted it to compost (Which Type of Worm Bin Is Best? 2010).

2.4.4.1.1.3 BinsThe bin approach is similar to the bed method, with the addition of a holding container, sealing the compost process off from the outside environment (Which Type of Worm Bin Is Best? 2010). Figure 2-5 contains an example of a wooden bin system.

2.4.4.1.1.4 StackableThe stackable system involves multiple units stacked or lined up with each other, with openings in the bottom and top to allow for the worms to traverse the different bins (Figure 2-6, Figure 2-7). New bins always go on top, or one side (if horizontally stacked), and old bins are always removed from the bottom or the opposite side as introduced. This allows for the worms to decompose one bin, and then move on to the next, always headed towards the newest material. By the time the bottom bin needs to be removed it should be fully processed with few worms left (Which Type of Worm-bin Is Best? 2010).

2.4.4.1.1.5 Closed LoopIn the closed loop setup, the cycle is fully contained in one area, meaning there is no management needed. The only work is depositing the food waste, and removing the compost once finished.

2.4.4.1.1.6 BedsBeds are one of the simplest methods of vermicomposting and involve very little construction. They are simply a holding container, usually in the garden, where food scraps are left in a pile to decompose and shoveled out after full decomposition, or the worm bed is converted directly into a garden bed (Which Type of Worm-bin Is Best? 2010).

2.4.4.1.2 Examples

Figure 2-5: A bin system built with wood materials (http://www.worm-bins.net/)


Figure 2-6: A bin system built with plastic materials (http://kitsap.wsu.edu/hort/worm_bin.htm)

Figure 2-7: An example of a stackable vermicomposting bin (http://i1043.photobucket.com/albums/b435/WorldTreeGardening/Available%20Products%20%20Services%20and

%20Concepts/Compost%20bin%20designs/worm-composter-diagram.jpg)

2.4.4.2 InputThere are several factors that can have a negative result on the worms and the usability of the compost, based on the input material. Shredded paper is a material often used with vermicomposting in conjunction with organic materials. The problem with paper is that the ink can sometimes contain toxins that can create problems for the worms. Oils and salts should also be kept out of the worm bin. “Worms breathe through their skin. To do this, their skin must stay moist. Oils will make it impossible for their skin to absorb air and salts will pull moisture from their body. Oils and salts could dehydrate, suffocate, and kill the worms.” (What Do Worms Eat?) Large portions of food must also be broken up and foods that takes a long time for worms to decompose should also be avoided. If the food is allowed to sit for too long it will quickly be susceptible to mold and other unwanted pests. Large quantities of grass clippings and plant material can also kill the worms, due to the large amounts of heat generated by the decomposing organic material. “Grass clippings in worm bins will heat up and kill your worms. You can feed them to the worms, but only in extremely small quantities” (What Do Worms Eat?).

2.4.4.3 CapacityIf the frequency of input becomes too much for the structure of the worm bin, there is risk of structural failure that would compromise the entire project. Another possible issue is odor. Predictions and calculations will have to be made to ensure an appropriate holding container for the decomposing food


and organic material is built. “Odor is minimal if you don't overload the system. Worms in a 16"x19"x12" bin can process 2-3 pounds of garbage a week. Capacity of a 20" x 24" x 12" bin is up to 5 pounds of garbage a week” (NSTA 2008).

3 Search for Alternative Solutions

3.1 IntroductionSeveral brainstorming sessions were held to develop alternative solutions. Seven alternative solutions were invented. The disadvantages and advantages of each individual solution, as well as how each solution met the criteria, specifications and considerations, were discussed.

3.2 BrainstormingIn the brainstorming sessions, various issues and solutions for the school worm bin were discussed. During the first brainstorming session, all issues regarding common solutions were talked about and each solution was shaped to the considerations and specifications of the project. In another session, the pros and cons of each of the seven solutions. After doing so, each of the alternative solutions was further developed. Each group member participated equally and came up with solutions individually.

3.3 Alternative SolutionsEach brainstorming session refined seven different alternative solutions designs for school worm bins. Each of the solutions follows the specifications and considerations from Section 2. The seven alternative solutions are:

Barrel O’ Fun Drawers O’ Worms Cin-Bin The Worm Tower The Compost Chute Worm Wheel Circle of Life

3.3.1 Barrel O’ FunThe Barrel O’ Fun worm bin is a simple and easily constructed worm bin. It is created from a non-toxic wood, plastic, or metal barrel. How the Barrel O’ Fun worm bin works is demonstrated and explained by the components labeled A-G in Figure 3-8. At the top of the worm bin there is a lid labeled by A. The lid has small holes drilled near the edges to allow airflow so odor cannot build up. B shows where the waste and compost materials are put in. There is a viewing area built into the side of the barrel, as shown by C. The viewing area consists of a Plexiglas square so people can see into the worm bin, and a cover so when the viewing area is not being used. At the bottom of the barrel, there is a flap that is can be latched to the barrel labeled by D. This flap will allow the barrel to be emptied of worm compost and castings with minimal effort. The area labeled by E shows where fluids drain. There will be holes drilled around the bottom of the barrel for drainage. F simply shows the direction the waste will be placed and the way it will be digested by the worms. Lastly, G demonstrates the direction the barrel will be emptied of compost, leftover waste, and worm castings.


Figure 3-8: A drawing of the "Barrel O' Fun" (Drawn by Paul Johnston)

Since the Barrel O’ Fun worm bin will be constructed out of wood, plastic, or metal, it will fulfill the criterion for durability since all of these materials can last long term. The Barrel O’ Fun can be painted by students with non-toxic paint. This will make the Barrel O’ Fun worm bin more aesthetically pleasing. This will also make the students a little more interested in the Barrel O’ Fun worm bin. The Barrel O’ Fun worm bin will be completely made of non-toxic materials, making its use much safer and fulfilling the safety criterion. The final material cost for this project will be one of the lowest costs compared to the other alternative solutions.

3.3.2 Drawers O’ WormsThe Drawers O’ Worms worm bin is similar to a dresser. The way the Drawers O’ Worms works is shown through the letters A-G in Figure 3-9. Each individual drawer shown by A and B can be used for a different species of worm for educational purposes. Food for the worms can be placed in each drawer and be pulled out for easy removal of the worm castings after the worms have digested all the natural waste placed in the drawers. There are small holes drilled into the bottom of each drawer to allow drainage of fluids. E shows how gravity will pull any waste or fluid that has not been digested by the worms down through each drawer to maximize total composted waste. Underneath all the drawers there is a basin, shown by C, that catches all the worm castings, compost, and other wastes that leak out of the holes drilled in the drawers. The basin can be removed of little holders shown by F. The back and sides of the Drawers O’ Worms worm bin will be covered, shown by D. Each siding and the back will have a few


holes drilled into them so odor will not build up and the compost can have a constant flow of oxygen. Lastly, shown by G, the table’s top can be used to sort through castings or waste or to separate waste before placing the waste into the drawers. The tabletop is there for the user’s maximum convenience.

Figure 3-9: A drawing of the "Drawers O' Worms" (Drawn by Paul Johnston)

The Drawers O’ Worms worm bin can be made out of a non-toxic pressure treated wood, similar to what is used for patios or decks. This will fulfill the criterion for durability since pressure treated wood lasts for around 10 years. Since the Drawers O’ Worms worm bin is being designed for a school, to make it more aesthetically pleasing, students will be able to paint it with non-toxic paint. The Drawers O’ Worms worm bin will also fulfill the educational specification because children will be able to have a hands-on experience as the drawers are easily accessible. The Drawers O’ Worms worm bin will be made of non-toxic materials, meeting the most important criterion, safety. Also, the cost to build this project will be much less than expected since wood is not very expensive.

3.3.3 Cin-BinThe Cin-Bin worm bin consists of a raised bed made from cinder blocks, with internal dimensions of 2’x2’x2’. The bedding, which consists of a mixture of horse manure, shredded paper products, and peat moss, is placed inside. After the worms are added, food waste is added to the top of the pile. The Cin-Bin can be left uncovered or a cover can be put in place. Bins can be connected to each other by placing them so they share a wall as seen in Figure 3-10. This wall can be composed of hollow cinder blocks, allowing the worms to travel from one bin to another. This method can be used to shift the worms from completed compost to new compost. The old bin can then be harvested and refilled. Each bin is fairly simple in construction and removal.


The Cin-Bin is fairly safe, as it is low to the ground and can be easily covered. It is simple, as it consists solely of cinder blocks. The cinder blocks are fairly durable, so the Cin-Bin can last for several years. Cinder blocks can be found for free or bought at approximately $1 per block, making the Cin-Bin relatively cheap. The educational value of the Cin-Bin is not the greatest, but it does allow a close up look at the inner workings of the bin. The Cin-Bin is fairly efficient, especially if the worms are allowed to travel from one bin to the next. The Cin-Bin is extremely extensible, as it easy to add more cinder blocks create a new bin. The Cin-Bin is not the most aesthetically pleasing design, but the blocks could be painted or other decorations added in order to improve its looks.The main advantages to the Cin-Bin are its extensibility, simplicity, and durability. It is easy to harvest from as well. The main disadvantages are the laborious construction and transportation of parts.

Figure 3-10: A sketch of 3 Cin-Bins arranged in series. (Drawing by Paul Sereno)

3.3.4 The Worm TowerThe Worm Tower consists of four walls of 2”x4”x24” lumber, each wall held in place by four metal rods, two on the inside and two on the outside, which is evident in Figure 3-11. Each inner corner shares a rod, for a total of twelve rods used. The bedding, which consists of a mixture of horse manure, shredded paper products, and peat moss, is placed inside, to a minimum depth of one foot. After the worms are added, food waste is added to the top of the pile. A wooden lid is then placed to cover the pile. Over time, the bin will fill with compost, and the worms will migrate to the top of the bin. When the oldest material has decomposed sufficiently, the bottom slats can be pulled sideways and removed in order to harvest the compost at the bottom of the bin, as seen in the Figure 3-11 inset. The slats can then be slid back in, or the entire wall can be shifted down, with the slats being placed at the top.The Worm Tower meets the safety criterion, as the entire unit is enclosed. Both the complex construction process and moving the slats in order to harvest lower the simplicity of the design. The Worm Tower is fairly durable if rot-resistant wood is used. The cost of the Worm Tower can vary, but is slightly higher


than other designs, due to the use of rot-resistant wood and the metal rods. The Worm Tower is fairly efficient, allowing the worms to work their way through each layer before moving up the bin. The Worm Tower is not extensible, as it would require the removal of a wall to add on another bin. The Worm Tower can be aesthetically pleasing, if quality, rot-resistant woods are used, such as cedar.The Worm Tower’s main advantages are its aesthetic value and safety. However, the Worm Tower lacks in simplicity, due to a fairly difficult construction process, as well as possible difficulties in moving the slats to harvest.

Figure 3-11: The Worm Tower, with overhead view. (Drawing by Paul Sereno)

3.3.5 The Compost ChuteThe compost chute is a design for the worm bin that utilizes the bin method of having all the compost in one region, while utilizing gravity to make extraction easier. The structure consists of a square tube of

about 3-4 feet in height, with sides of approximately 1-1.5 feet. There will need to be a slide at the bottom of the chute at an angle; this can be seen on the right of Figure 3-12. The organic waste enters the Compost Chute by lifting the hatch on top and depositing the food in the tube. The compost is removed by raising the hatch at the bottom and allowing the compost to fall out into a bucket. Scooping with a trowel may be necessary to compensate for any compaction that may occur. This solution works by having worms start out on the bottom of the chute, near the exit hatch, and allows them to travel upwards towards new food waste. This ensures that food at the bottom of the chute will be fully decomposed before the worms start travelling upwards. A problem that would need to be addressed in this solution is the possible compaction of the compost due to the height of the structure. The materials used for this


solution are also an area of concern, due to the tube’s odd dimensions, as well as the durability of the final product.The Compost Chute is efficient and it is easy to deposited and harvest waste. However, it can be unstable depending upon its height. It is also difficult to construct and may not be very durable.

Figure 3-12: The Compost Chute, an alternative solution designed by Max Hullman

3.3.6 The Worm WheelThe worm wheel takes a circularly divided approach to the compartment method, while keeping the compost easy to remove and the structure easy to build. The circular structure for the compartments is built from used plastic lawn furniture tables, chicken wire for the compartment dividers (illustrated in the top right of Figure 3-13), and wood for both the supporting structure and braces for the chicken wire. There are also flaps on top of each compartment, with a locking mechanism, so that compost does not fall out. Waste food would exit at compartment A on the diagram, or whichever compartment was fully decomposed at harvest time. To do this, the flap is opened and the wheel is turned so that the compartment spills into a bucket. After the compost is removed, the Velcro smiley face indicator will need to be moved to the next compartment, so the next time compost needs removed it will be in chronological order. Issues to keep in mind in this solution are keeping the structure as simple as possible, as well as the availability of materials. The Worm Wheel is efficient, and it is simple to deposit materials and harvest compost. The soil is turned easily. However, the Worm Wheel is potentially dangerous and difficult to construct.


Figure 3-13: The Worm Wheel, an alternative solution designed by Max Hullman

3.3.7 The Circle of LifeThe Circle of Life solution utilizes the bed method. However, this solution varies from the usual bed method is that this bed wraps around in a circle, which means the new waste food is placed in the system with worms on either side, ensuring full decomposition before extraction. To remove composted material the rain cover is simply lifted back to reveal the bed, which can then be removed via a shovel or hand trowel. After compost removal, the rain cover is replaced with the bin identifier (Figure 3-14), facing the newly empty section. The advantages of this solution include a very simple design and cheap, widely available materials. Extraction is also made easy by having a very accessible holding container, with a system of identifying which section is fully decomposed. An issue with this design is that the timing of removal will need adjustment in correlation with the size of the final design. The Circle of Life is cyclical, keeping the worms in the system. It is built from simple materials and is easy to maintain. It does require a large quantity of materials, as well as the difficulty of constructing the circular shape. There is also a possible issue with leachate leaving the system.


Figure 3-14: The Circle of Life a vermicomposting solution by Max Hullman

4 Final DecisionThe final decision was made by consulting the preceding sections. All of these sections led to an ideal and suitable design solution. Also, the Delphi matrix, a chart for deciding how well every individual alternative design solution meets the criteria, was used.

4.1 CriteriaIn order to come to a decision on a solution, the criteria from Section 2 was used to critique each alternative solution. The criteria were used as follows:

Safety: This criterion is defined by a lack of structures that can cause harm to the user, as well as being nontoxic to humans and worms.

Cost: The cost is defined as the cost of materials to build and start the bin.

Simplicity: This is defined as being easy to construct and easy to maintain.

Educational Value: This criterion is met by teaching users about vermicomposting.

Durability: This criterion was determined by how long the worm bin would last through use and weathering.


Efficiency: In order for the worm bin to get a high rating in this criterion, the solution has to produce usable compost in a short amount of time.

Extensibility: The criterion was determined by how easily the worm bin could be reconstructed, and added to the previous worm bin.

Aesthetics: The worm bin had to appease the eye and look somewhat professional in order to meet this criterion.

4.2 Alternative SolutionsBrainstorming conducted by the Organic Flapjacks resulted in seven alternative solutions. Detailed descriptions of each alternative solution are located in Section 3. The team considered the following solutions:

Barrel O’ Fun Drawers O’ Worms Cin-Bin The Worm Tower The Compost Chute Worm Wheel Circle of Life

4.3 Decision ProcessThe Organic Flapjacks utilized the Delphi method, as well as client input to reach a final decision. The Delphi method consists of giving each criterion a weight from zero to ten (ten being most important), and then giving each solution a score from 0-50, depending on how well it fulfills the criterion. The result of this process is shown in Table 4-1. Each solution’s criterion score is multiplied by the weight of the criteria and then totaled. Group members scored the solutions, discussed each score, and agreed on each criterion score.

Table 4-1: The Delphi method for the school worm bin, with the scores of each solution based on the criteria.


4.4 Final DecisionThe Delphi method yielded these three highest scoring solutions: Barrel O’ Fun with 2171 points, Cin-Bin with 2290 points, and Circle of Life with 2287 points. After presenting all three concepts to the client, the list was narrowed down to the Barrel O’ Fun and the Cin-Bin. The team then consulted with the project supervisor Lonny Grafman and tried to combine concepts from each idea into one final solution. The result was to make the Barrel O’ Fun easily accessible by cutting the drum in half and raising it horizontally off of the ground. One half is nested in the other, and the worms are put in one half. When it is time to harvest, the worms are transferred to the other half. The Barrel O’ Fun is simple, cheap, efficient, safe, durable, educational, and extensible.

5 Specification of Solution

5.1 IntroductionSection 5.1 contains a description of the Barrel O’ Fun. The Barrel O’ Fun is built out of a 55 gallon drum on pallets. The design costs, construction costs, and maintenance costs are covered, and the instructions for implementation are given.

5.2 Solution DescriptionThe Barrel O’ Fun worm bin (Figure 5-15) is constructed from a plastic, food grade, 55 gallon drum. The drum is cut in half, longitudinally, and the end of one half is removed, creating a “nest” half. The intact half is laid inside the nest section and they are bolted together. A spigot (Figure 5-16) is installed at the end of the nest barrel to harvest worm compost tea. Two pallets, with a central trough cut out, are placed on top of cinder blocks. The worm bin is then placed on the pallet. A PVC cover support system () is constructed, and a plastic sheet is draped over the top. The sheet is then bungeed to the pallet.The cover is folded back in order to add waste to the bin. Over six to eight weeks, the worms will compost the waste. When it is time to harvest, only a corner of the bin is fed. This draws the worms to the top layer of compost in the corner, and they can be scooped up and placed in the other half of the bin. The full side can then be harvested. Waste is then added to the half with the worms, and the process continues. The build process is inexpensive and fairly simple. The Barrel O’ Fun is built from durable materials and is safe to use. It provides a great way to teach children about vermicomposting, and it is efficient, producing vermicompost in six to eight weeks. It is easy to create more bins, and it looks professional.


Figure 5-15: An AutoCAD drawing of three basic views of the Barrel O' Fun (drawn by Paul Johnston)

Figure 5-16: An AutoCAD drawing of the spigot and “nest barrel” (by Paul Sereno)


Figure 5-17: An AutoCAD diagram of the PVC frame for the tarp (Drawn by Paul Johnston)

5.3 Cost AnalysisA breakdown of the design, construction, and maintenance costs is provided in the following sections.The breakdowns will be in hours spent or required and dollars spent.


5.3.1 DesignThe design cost is the cost in hours spent on the project. The total cost is broken down into the time spent on each portion of the design process. As shown in Figure 5-18 below, a total of 69 hours were spent on the project. Section 1, Problem Definition, took three hours. Section 2, Gathering Information, took fifteen hours. Section 3, Alternative Solutions, took eighteen hours. Section 4, Analyzing and Selecting a solution, took six hours. Section 5, Implementation, took twenty-seven hours.

Figure 5-18: The design cost, in hours, spent on each phase of the design process.

5.3.2 ImplementationThe implementation cost includes the price of materials used to build the Barrel O’ Fun worm bin. The individual costs of materials are shown below in Table 5-1. As shown, the total implementation cost for the Barrel O’ Fun is $167.91. Retail cost for the Barrel O’ Fun is $268.74.

Table 5-1: Breakdown of material costs for the Barrel O’ Fun worm bin

Quantity Individual Cost ($) Retail Individual Cost ($) Retail Cost ($) Our Cost ($)1 40.00 49.95 49.95 40.002 donated 10.00 20.00 donated4 14.99 24.95 99.80 59.966 0.15 0.15 0.90 0.906 0.09 0.09 0.54 0.546 0.09 0.09 0.54 0.546 1.80 1.80 10.80 12.001 6.29 9.99 9.99 6.291 3.59 3.59 3.59 3.596 1.75 1.75 10.50 10.501 8.54 8.94 8.94 8.541 5.39 7.99 7.99 5.391 3.41 3.41 3.41 3.414 1.45 2.50 10.00 5.831 1.99 4.99 4.99 1.992 0.99 0.99 1.98 1.982 0.44 0.44 0.88 0.881 0.44 0.44 0.44 0.44

20 0.44 0.44 4.98 4.98Tax 22.38 11.37


5.3.3 MaintenanceThe maintenance costs can be broken into time costs and material costs, each with a weekly and yearly list of tasks that require attention. The total maintenance cost for one year is roughly twelve hours. This estimate consists of ten-minute weekly feedings and thirty minutes for harvesting the compost every six-eight weeks. In an eight-week period, the worm bin should produce roughly forty pounds of usable compost (assuming ten pounds of waste is put in the bin per week). Table 5-2 shows this below.

Table 5-2: Breakdown of time cost for maintenance

Task Time (min/year)Worm Feeding 520Worm Transfer 30Harvesting 180TOTAL (minutes) 730TOTAL (hours) 12

5.4 Implementation InstructionsThe first step, after obtaining a food-grade 55-gallon drum, is to cut it in half lengthwise as shown in Figure 5-19.

Figure 5-19: The 55 gallon barrel cut in half. (Photo by Paul Sereno)

After this, cut 3” off of one end of one half (Figure 5-20). This will make the “nest” barrel.


Figure 5-20: The removal of the end will create a "nest" barrel. (Photo by Paul Sereno)

Then, like in Figure 5-21, lay the intact half inside the nest barrel. Adjust the barrels until they overlap by 5”.

Figure 5-21: The barrels are connected and overlap by 5". (Photo by Paul Sereno)


Then a ¼” hole is drilled near the top of the connection on one side. The barrels are then bolted together with a ¼” bolt and nut, with the bolt head on the outside of the connection. This is repeated around the connection until the barrels are well connected (approximately 5-6 bolts). A hole is then drilled or cut at the end of the nest barrel for the spigot (Figure 5-22). The spigot is then installed.

Figure 5-22: The spigot, installed. (Photo by Paul Sereno) Next, drill 5-10 ¼” holes at the bottom of the dividing wall for drainage (Figure 5-23).

Figure 5-23: 1/4" drain holes are drilled into the dividing wall. (Photo by Paul Sereno)


A gutter strainer is then trimmed so that it will lay flush with the bottom of the barrel, and cover the entrance to the spigot. 100% silicone caulk is then applied to the area around the spigot, and is also used to glue the gutter strainer to the bottom of the barrel as in Figure 5-24.

Figure 5-24: Silicone caulk is used to glue the gutter strainer over the entrance to the spigot. (Photo by Paul Sereno)

The outside of the connection is caulked as well, in order to prevent leaking, as shown in Figure 5-25. The caulk is then allowed to set for at least 24 hours.

Figure 5-25: The outer connection is caulked to prevent leaking. (Photo by Paul Sereno)


After the caulk has set, the base is created. Six cinder blocks are placed underneath the corners of the pallets, as in.

Figure 5-26: The pallets and the cinder blocks set in place. (Photo by Paul Johnston)

The pallets then have the center of the top planks removed, like in Figure 5-27, creating a trough.

Figure 5-27: The trough is cut into the pallet. (Photo by Paul Johnston)

The barrel is then placed in the trough. The end of the barrel opposite the spigot is elevated by placing a 2”x4” across the trough as seen in Figure 5-28.


Figure 5-28: The barrel is placed in the trough. (Photo by Paul Johnston)

The connection of the barrel is supported by placing a small cut of 4”x4” lumber inside the trough. The rain cover is constructed with ½” PVC piping. For this barrel, four 2’7” lengths, two 7¼” lengths, two ½” T-joints, and one ½” 90° elbow are used. In , two of the 2’7” sections are joined by a T-joint, to make a total of two 5’2” crossbars that will span the length of the barrel.

Figure 5-29: The T-jointed crossbars that span the barrel. (Photo by Paul Sereno)


¼” notches are cut 1” from each end. As seen in Figure 5-30, these notches hold the crossbars in place.

Figure 5-30: A 1/4" notch is cut in each end of the PVC. (Photo by Paul Sereno)

The crossbars are placed apart by 9½”. The 7¼” sections are joined by the 90° elbow. In Figure 5-31, the free ends of the sections are placed in the free opening of each T-joint, to provide a tent for the 10 mil plastic sheet.

Figure 5-31: The elbow piece is inserted, which will tent the plastic sheet. (Photo by Paul Sereno)

The 10 mil plastic sheet is laid over the top and cut, with an overhang of at least 6” on each side. Grommets are installed at each corner of the sheet, folding over the corners for extra strength. The worms are then added to the bin, along with compostable waste and the bedding material (horse manure or shredded paper), as seen in Figure 5-32.


Figure 5-32: Worms are added to the bin. (Photo by Paul Johnston)

Worms should be added at the ratio of one pound of worms to every half-pound of waste. The sheet is then bungeed to the pallet with four 24” bungee cords. One end is hooked into each corner, and the other end is wrapped around a board on the pallet. In Figure 5-33, the sheet is then adjusted to ensure a snug fit.

Figure 5-33: The sheet is bungeed to the corners of the pallet, and adjusted for a snug fit. (Photo by Paul Sereno)

The sheet is removed weekly in order to feed the worms. After approximately 6-8 weeks, the vermicompost should be ready to harvest. When it is time to harvest, only one corner of the bin (about one quarter of the surface) is fed. Over a few days, the worms should migrate to this area. This area is then scooped up and placed in the empty half of the bin along with more waste and bedding. The vermicompost can then be shoveled out of full half, and the cycle continues.Over time, due to the breakdown of organic waste, leachate will build up at the bottom of the bin. As the barrel is elevated, the leachate should drain through the drain holes in the divider and down to the spigot


area. The spigot can then be opened and the leachate collected. The leachate can be mix at a ratio of 1 cup of leachate to 2 gallons of water. The resulting liquid can be applied to soil or plants.

5.5 Prototype PerformanceThe Barrel O’ Fun was constructed at the Jacoby Creek Charter School garden. The barrel was seeded with four pounds of E. fetida worms (red wigglers). After one week, an increased amount of soil was observed. The PVC cover was constructed one week later and installed, two weeks after the bin was first started. More soil was observed, and the worms were still present. A return to the Barrel O’ Fun three weeks later found a considerable amount of compost and large worms, indicating that the system is working efficiently.

6 Appendices

6.1 Appendix A: ReferencesAgarwal, S.K. Advanced environmental biotechnology, APH Publishing Corporation, New Delhi, pg

341-343Aira, M., Domínguez, J., and Monroy, F. (2006). “Eisenia fetida (Oligochaeta, Lumbricidae) Activates

Fungal Growth, Triggering Cellulose Decomposition during Vermicomposting.” Microbial Ecology, 52(4), 738-747.

Arcata, CA Weather. (2011). Retrieved February 21, 2011, from IDcide: http://www.idcide.com/weather/ca/arcata.htm

Arvind Kumar, Verms and Vermitechnology, S.B.Nangia, 5, anasari Road, Darya Ganj New Delhi, pg17-18

Bohlen, P.J. and Edwards, C.A. (1996). Biology and Ecology of Earthworms, Chapman and Hall, London.

Elcock, Gillian. (1995). “Composting with Red Wiggler Worms” <http://www.cityfarmer.org/wormcomp61.html> (February 17, 2011)

Haug, R. T. (1993). The Practical Handbook of Compost Engineering. Boca Raton, Florida: Lewis Publishers.

Lodge, James. (November 1985). “Materials Damage by Environmental Pollutants: Data Requirements.” The American Statistician, Vol. 39, No. 4, pp. 412-415.

Munroe, Glenn (2005). “Manual of On-Farm Vermicomposting and Vermiculture.” Organic Agriculture Centre of Canada, <http://www.organicagcentre.ca/DOCs/Vermiculture_FarmersManual_gm.pdf> (Feb. 20, 2011).

Mycological Society of America. (2005). Isolation and Identification of Fungal Communities in Compost and Vermicompost. Mycologia , 97, 12.

NSTA. "Vermicomposting - Flowerfield Enterprises/Flower Press." Worm Composting Resources. Aug.-Sept. 2008. Web. 22 Feb. 2011. <http://www.wormwoman.com/acatalog/vermicomposting.html>.

Parrish, R. (2010, 5-May). How to Treat a Wood Worm Bin. Retrieved 2011 йил 18-February from eHow: <http://www.ehow.com/how_5994257_treat-wood-worm-bin.html>

Parthasarathy, V. A., Organic Spices, New India Publishing Agency, Pitam Pura, New Delhi, pg 77-87Schlenker, B.R. (1969). “Introduction to Materials Science” John Wiley and Sons Australasia Pty Ltd. 63-

273Werner, Matthew (1990). “Earthworms: Renewers of Agroecosystems.” UC Sustainable Agriculture

Research & Education Program, <http://www.sarep.ucdavis.edu/worms/> (Feb. 20, 2011).What Do Worms Eat? (n.d.). Retrieved 2011 18-February from Vermicompost:

http://www.vermicompost.net/worm-composting/bin-food/what-do-worms-eat.aspx


“What is CDX Plywood?” (1995). <http://www.doityourself.com/stry/what-is-cdx-plywood> (February 17, 2011)

"Which Type of Worm Bin Is Best?" Wormilicious — Diary of a Worm Composting Revolution. 18 Dec. 2010. Web. 22 Feb. 2011. <http://wormdiaries.organic-raised-bed-gardening.com/2010/12/18/which-type-of-worm-bin-is-best/>.

Worm Bin Setup. (n.d.). Retrieved 2011 18-February from Wormpost Vermont: http://www.wormpost.com/wormbins/setup.html

Zoe Hartman, 2010, "What Goes Into a Compost Bin?” <http://www.gardenguides.com/78221-goes-compost-bin.html > (Feb 21, 2011)

Zorba Frankel, 2010, "What is Vermicomposting and Why Do It?" < http://www.allthingsorganic.com/How_To/01.asp > (Feb 21, 2011)

6.2 Appendix B: Brainstorming Notes

Figure 6-34: Brainstorming Notes on March 1, 2011


Figure 6-38 Brainstorm of possible designs on March 1, 2011

Figure 6-39 Brainstorm of possible issues on March 1, 2011

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