A landfill is a scientifically run waste burying operation. At its most basic level, a landfill is a place where household, construction, industrial, special, or other types of waste are buried in a specially constructed hollowed-out area of land. Landfills are specifically designed to prevent contamination of the environment by the buried waste. This is the difference between a landfill and a dump. A dump is an illegal, unregulated place where waste is dumped into the environment. Landfills are legal, regulated waste disposal sites designed to prevent environmental contamination.

Building a landfill can take a number of different forms, here is one way.
First remove the topsoil from a hillside.
Secondly build up the hillside to the specifications and slope needed.
Third after the subgrade is in place, put four six-inch lifts of crushed shale clay over the entire hillside and compact each lift to form a two-foot thick clay barrier between the environment and the liner.
Fourth, with the clay in place get a liner company to lay roughly heavy-duty plastic liner materials over the area. The liner materials should include:
A geo-synthetic Bentomat layer which will seal any possible leaks in the plastic liner.
A heavy-duty plastic liner installed with no gaps between the panels.
A tri-layer filter fabric designed both to protect the plastic liner and to direct water flow.
Finally the waste is placed in lifts, being careful not to puncture the liner. Any items that could puncture the liner are removed from the first ten feet of waste and reburied later.
Steps should be taken to ensure that the least amount of rainwater enters the landfill by using berms and ditches to control runoff and direct the water around the waste. Some portion of rainwater may well enter the landfill and run through the waste. This water, having passed through the waste, is known as leachate. The leachate works its way through the trash and runs along the filter fabric laid just above the plastic liner. This leads the leachate into pipes which are buried in the waste. These pipes take the leachate to collection and storage tanks where the leachate is kept until it is either recycled through the landfill or hauled to a certified wastewater treatment plant.