Team 22

Group 4 Project – Constructing a Compost Bin Out of Tires : 

Group 4 Project – Constructing a Compost Bin Out of Tires By Xantha Leatham, Oliver Roberts, Chloe Doran, Ward Krebbers, Wesley Marwing and Anthony Lam

Introduction : 

Introduction For our group 4 project we chose to design and construct a compost bin out of old tires. Having compost bins in and around the school will provide the school gardens with fertile soil (for free) and it is an environmentally friendly choice as it ensures that any organic waste will not end up in land fills. Our aim was to design a compost bin which was not only functional but was easily moved, constructed, efficient, environmentally friendly, had easy access and did not take up a lot of space. When designing the compost bin, we needed to take into account the following factors: The material we would use (cost, durability and how easily it could be transported) Ventilation (the bin needed a good supply of air to aid the decomposition process) Pests and animals (prevention of their entering and nesting) Turning the compost (so that each layer gets a fair amount of air and warmth) The design of the lid (it needed to be strong and durable to protect the compost) The moral, social, ethical and environmental impact of our design

Reasons for using old tires: : 

Reasons for using old tires: There is almost one scrap tire created for every man, woman and child in the United States every year. This shows that tires are in plentiful supply and are readily available and cheap. In 2001, nearly 281 million tires were discarded in America alone. There is no appreciable risk in using old tires in the garden. Though they do contain small amounts of certain heavy metals, the compounds are tightly bonded and so do not leach into the soil and so do not damage the surrounding environment. Zinc is found in tires, and is also an essential plant element. This means that the tires will actually be providing nutrients for the plants. Tires are very durable and will last a long time since they do not rot.

Designing the compost bin : 

Designing the compost bin We worked together to come up with a design for the compost bin. We discussed our ideas and came up with an original design, taking into account factors which influence decomposition, such as air supply. However, our final bin differs from our initial design because we realised that some aspects of the bin needed to be changed. The next few slides demonstrate how we constructed the final compost bin.

Step 1 : 

Step 1 First of all we gathered our equipment: 3 tires Coloured pencils Sanding disk Bastard file Half-round file Screws Wooden blocks Chicken wire Pliers Cable ties Plywood sheets Power drill

Step 2 : 

Step 2 We delegated different tasks for each person to carry out within the group, to ensure efficiency. Ollie, Wesley and Ward were responsible for ventilation and handles. Chloe and Xantha were responsible for the chicken-wire meshing. Anthony was responsible for designing and creating the lids to go on top of the bins.

Step 3 : 

Step 3 Ollie, Wesley and Ward began by drilling holes on all sides of the tires. The top holes were for supporting the wooden blocks which were later attached to ensure ventilation. The holes on the sides were to attach the recycled land cables as handles, to allow for easy transportation of the tires.

Slide 8: 

Here we can see how the wooden blocks would support the tire and lift it off the tire below, which would allow for ventilation. The handles on the side meant that the tires could be easily moved.

Step 4 : 

Step 4 Chloe and Xantha cut the wire mesh into the correct shape for the tire. We decided to use two layers to ensure stability and strength. The wire was placed on the bottom of each tire so that as the compost broke down, it would be filtered down to the bottom layer.

Step 5 : 

Step 5 Anthony designed and cut the lid for the compost bin. We decided as a group to make a lid that would fit into the compost bin, which would allow some water to pass into the bin to aid the decomposition process, whilst at the same time protecting the compost from animals. He added a handle to the lid to allow for easy movement.

Slide 11: 

Chloe then used the pillar drill to drill holes into the lid which we then passed wire through to make a handle.

Self-evaluation : 

Self-evaluation We believe that as a group we worked really well together. Despite initial problems with the design, we overcame these difficulties by discussing our ideas and brainstorming ways to solve the problem. The division of labour worked extremely well because it meant that people could get on with their own tasks. We managed to complete not only one but two compost bins, which demonstrates how well and efficiently we worked together.

Questions for next year : 

Questions for next year We realised that as the compost bins came into use, there would be the possible problem of pests. We decided then that a good question for next year would be: What additions can be made to the design to prevent pests from entering and nesting in the compost bin? Also, the compost would need to be turned on a regular basis, and so another question could be: 2. Research and finalise an efficient way of turning the compost to improve the effectiveness of the decomposition process. We believe that these questions would allow future groups to investigate the ways in which the compost bin can be improved to provide good compost for use by the school.