What becomes of landfills after their use as a landfill is exhausted?
In terms of land development, greenfields are areas that haven't been
previously developed, like farmland.
Brownfields are usually areas that have been
contaminated to some degree by industrial activity and aren't necessarily
suitable for residential or agricultural use, but can be redeveloped for
commercial or industrial use.
By redeveloping old landfill sites, and any other brownfield site,
greenfields are saved. On a local level this sometimes does not seem to
be an issue, but not using this
space means using greenfields for development of residential and
industrial areas and losing several acres of nature.
Developing on closed landfill sites is becoming more and more common as an increasing number of landfills are being closed, leaving an empty space to build on. Land near urban areas is in higher demand, making this prime real estate after some special preparations for the land are taken into consideration.
Geotechnical experiments should be performed. Below-ground investigations are done by boring, sampling, and testing the soil strata to establish its compressibility, strength, and other characteristics likely to influence a construction project. This is also called foundation investigation, soil investigation, soil test, or subsurface investigation and is necessary to determine the stability of the ground on which the building will occur.
Some housing developments and businesses report such things as sinking or uneven floors.
Water testing should be done and continued at regular intervals for a determined period of time. Many old dumpsites did not have liners to prevent groundwater contamination.
When the dumps were full, they were typically covered with loose topsoil.
Rainwater and precipitation can seep into the waste and carry chemicals to
the groundwater below. Because some old dumps used wetlands for disposal
sites, the wastes were directly in contact with the groundwater table.
Testing for gasses should be performed. Landfills produce methane gas which is held in pockets within the ground. As the dirt is moved to cover and recover landfill debris, some of this methane is released and usually burned off. This leaves the landfill safe from spontaneous combustion due to the build-up of methane.
The Environmental Protection Agency (EPA) typically requires developers to cover landfills in a thick layer of clay and install
wells and pipes that shunt landfill gas to a flare. Some developers also are require the installation of
pumps to keep landfill liquids, called leachate, contained.
If done correctly, closed landfill sites are perfect pieces of land on which businesses or housing developments can be built. If shortcuts are taken without regard for an inevitable outcome, anything built on these sites risk sinkholes, shifting, and uneven structures.
More information on landfills is available by visiting www.wasteawaygroup.com.