WHAT
Today's worm composters are small and made to be placed inside your home. For a school project on 'Urban Gardening' we were given the task to build a real big worm composter that could be used for neighborhood composting in allotment gardens. This instructable contains the concept we worked out.

ADVANTAGES

> Large: This method of building a worm composter is suitable for neighbourhood composting. The one we made fits the total kitchen waste of 10 big families. Who might otherwise throw food waste in the bin.

> Scalable: The bin can easily be scaled according to your wishes.

> DIY: We opted for very simple techniques and connections, the only tools needed are a cutter and knife.

> Re-use of leachate water: in most compost bins the leachate water isn't captured and flows in the ground. Our system provides a re-use of the leachate water, which can be used as a natural fertilizer.
> Cheap: use of common materials

WHERE
The construction has to be placed where there's enough shadow during the day, because the worms prefer room temperature (20°C; 70°F).

IMPORTANT

This system guarantees only good compost if some important rules are observed. It's a worm composter, so you can't trow everything in it, the worms won't eating it all.
So if the installation is used for neighbourhood composting, make sure there's good communication about using the system well! That's why we put a picture of our 'communication panel' in this instructable.

If you want to try out this system, we still recommend to consult a composting expert.

COST

We made a table of total cost of the installation IF you have to buy everything new. We suppose most materials are already available at home. So cost will be less then underneath.

PART_______________COST

tripod poles (x6)_______€ 3.20 x 6
bridging poles (x2)_____€ 4
mesh wire____________€ 5
waterproof foil_________€ 2.60
geotex cloth__________€ 10
covering sheet________€ 5.5
rope(75m)___________€ 2.75
zip ties______________€ 2.5
TOTAL COST_______ € 55.55

Taking a quick look at costs and materials you already have at home, teaches us the construction can be made for about 25 euros.

Step 1: Materials and Tools

Material list:

- 6 short poles (tripod legs)
- 2 long poles (frame)
- wire mesh, garden fencing (support)
- large water-permeable tarp (to keep in our worms and dirt)
- foil to catch leachate
- tarp to shield against heavy rain
- rope for lashing
- zip-ties
- some sticks
- bottle or two

Tools:

- knife
- combination pliers

Step 2: Making Tripods

The final construction is very strong, this strenght is accomplished by two tripods that hold the frame.This is how the tripods are constructed.

The tripods are made by lashing rope around 3 poles.

You need two tripods. Don't forget to tighten the rope regularly! Feel free to use some waterproof rope.

Very good tutorial in case lashing isn't really clear yet by our pictures:
http://www.animatedknots.com/lashtripod/

Step 3: Bridging Tripods

Next we place the tripods at about the distance of the long poles. The long pole should overlap at each side so we can lash them to the tripod. Next find some support to put the pole on (or have a handy friend) and use a square lashing to fix it in place. For the height, just make sure you can still reach over easily and that you have some ground clearance in the next step.

http://www.animatedknots.com/lashsquare/

Step 4: Install Garden Fence (support)

Next we will hang our wire mesh as a basket between the bridging poles, Keep well off the ground and use some rope to attach it. Try to cut off any sharp edges, this can only save you some pain later.

Step 5: Place Leachate Water Catching Foil

Now for the most annoying step, as it's the only one that requires some precision and maybe a few pairs of extra hands.
The goal is to catch all the liquid that runs down from our compost, and guide it to some vessel.
It's pretty easy to use zip-ties to connect it to the mesh, but you will have to take it slow and check and recheck with some water, to make sure it runs to one side properly.

Make sure you get a gradual slope to one side!

Step 6: Place Geotex Cloth

Now we place the geotex cloth (weed barrier).

Why geotex? Functions:

- Leachate water can go trough and is then caught by the foil underneath.

- The cloth can 'breathe', so the compost is ventilated well.

Buy the right size of weed barrier or cut it in the right dimensions. The cloth hangs out a little bit on both sides and don't have to be fixed to the construction. We rolled the edges over a bamboo stick to stabilize the cloth and protect the fragile ends of the weed barrier.

On the narrow sides of the bin you can make a support with a little stick(we used bamboo) where the cloth is hanged over.

Last picture shows the construction after completing this step.

Step 7: Place Covering Sheet

The final step is to place the covering sheet, this prevents the compost of becoming soaked by the rain.

We first link the tripods with a cord or bamboo stick where the covering sheet will be hanged over so rain water is drained and can't remain stagnant on the sheet.

You can now fill the bin and start composting!
Get some worms from a friend or go hunt for them in a field.

(Pay attention to some rules so that worm composting is working well)