If your large household or your school or cafeteria wants to begin steering its food scraps out of the garbage can and into a more productive use, consider constructing a substantial vermicompost system capable of handling appropriate food in quantity. Such a vermicompost setup creates a mini-ecosystem where both food and cardboard-type wastes become munchable lunchables for compost worms. The worms, typically red wigglers or Eisenia fetida, pass food sources through their systems and create a bacterially rich manure that enriches gardens.
Collect food scraps for a week to ascertain the size of vermicompost system needed. If your household or cafeteria generates 6 lbs. of scraps daily for five days a week, you'll need 30 square feet of surface bin space, based on a formula of 1 square foot of surface area per lb. of food waste, according to Rhonda Sherman of the North Carolina State University Extension Service.
Design a bin 4 feet by 8 feet, offering 32 square feet of surface area, to handle 30 to 32 lbs. of waste per week. Construct multiple bins as needed for larger quantities.
Dig an outdoor pit 6 feet wide by 10 feet long and 18 inches deep. Line the hole with hardware cloth of ¼- to 3/8-inch mesh to keep out rodents. Pour 6 inches of gravel, sand or crushed stone to aid drainage and level it with a rake.
Construct four frames measuring 4 feet by 8 feet by 12 inches, using pressure-treated 1-by-12s. Use long screws to create butt joints in the lumber. Create handles by adding 2-by-4s on the outside of each side of the frame toward its upper edge. Lay more hardware cloth under the bottom of one of the frames and bend it up the sides to fit snugly; do not attach the wire to the frame.
Set the frame, wire side down, in the pit. The frame’s top should be flush with the ground and the sides centered in the middle of the pit.
Fill the perimeter gap of 1 foot with cinder blocks so the solid side parallels the ground and they hold the wire against the frame. Add sand or excavated material to fill the gap between the blocks and the pit wall.
Stack the frames one at a time on top of each other. Add 1-foot-long lengths of 2-by-4 to the inside corner of each frame so that they project 6 inches into the lower frame and create a solid structure that won’t slip.
Screw 2-by-2 wood strips under a sheet of 4-by-8-foot marine-grade plywood, which will serve as the lid, to keep the lid centered on the top frame. Add blue insulating board to the lid on the inside of the strips.
Fill the bottom frame with moistened cardboard or paper bedding. Place worms on top of the bedding. Add food scraps in the pocket created in the bedding and cover with at least 1 inch of bedding material.
Add bedding in sufficient quantity to replace the original amount as it becomes converted and to cover the food scraps.
Separate the vermicompost, which will look like dark crumbly earth, from the worms after three months. Add vermicompost to the garden and return the worms to the frame to repeat the process.