Hello everyone, recently I shared with you my visit to one of Ghana?s largest landfill site. I reported on some features of the landfill but not the design of the landfill site and whether or not, the landfill pollutes the environment - particularly underground and surface water. So I have put together the design of the Oti Landfill located within the Kumasi Metropolitan Assembly in Ghana.

Waste collected contains high organic content and other substances which decomposes and produces leachates. These leachates can seep into underground water and contaminate it. Leachates also gets in contact with surface drinking waters and pollute them. To prevent this, one of the objectives of the Oti landfill is to treat the waste such that the leachates cannot contaminate both surface water and ground water.

Refuse brought to the landfill is tipped into a cell- the cell is an excavated pit or area of about 3-4 meters deep. The cell inside is coated or lined with a very thick layer of clay. The clay linen should be about a meter thick so that it can prevent seepage of the leachates into the ground water. Afterwards, a geo-membrane (a plastic round material) is place on top of the clay lining to also prevent leachates? seepage. The geo-membrane takes a long time to decompose due to its plastic nature and so, it can prevent leachates seepage for a very long time.

A fish like bone system of pipe is arranged with geotextile placed on top. The larger and smaller pipe design is being laid in the cells to collect the leachates and contaminated water in the cell to a stabilization pond.  It can rain for a long time but there will be no stagnation of water because of these pipes. The purpose of the geotextile is to prevent solid materials from entering the pipes. After that terrazzo chippings are used to cover the geotextile.

To serve as a control, there are bore holes around the stabilization ponds where water sample is taken periodically to determine the quality to know whether there contamination or not.

Upon my visit, I was educated on actual operations and a lot more technical designs of the landfill while I also witnessed the level of compliance practiced by management of the landfill. I will put that into writing and share with you soon. Thank you.