This research is aimed to study the design and construction of hazardous waste landfills with respect to the long term performance. The main purpose of the design and construction of these facilities is to isolate such wastes from the biota in the form of tightly designed landfills. Hazardous wastes can be defined as the waste that causes substantial or potential threats to biotic receptors. These wastes have properties that make the waste to be considered as hazardous; ignitability, corrosivity, reactivity and toxicity. Chemical wastes and low level radioactive waste like Depleted Uranium (DU) are considered as hazardous waste and contained in the form of near-surface landfills.
Iraq has passed through many destructive wars and there are chemical wastes and depleted uranium (DU) left over. Some of this waste is exposed and the remainder was buried without any consideration to human and environment protection. These wastes are mainly located at the middle and southern parts or Iraq. Now it is of great necessity to contain these wastes by constructing an engineered near surface landfills close to the contaminated areas, namely western desert and Aljazeera desert where rich clay soil is available as a raw material for liner construction. The landfill is mainly composed of tight top cover (top liner) and the bottom liner. The key to long term performance of landfill is to design a tight top liner which will allow the percolation of precipitation within the acceptable limits, in other words, it should has low permeability (low hydraulic conductivity). Liners could be construction from compacted clays, geo-synthetic clay, geo-membranes or a combination of them.
There are international regulations concerning the design of hazardous waste landfills, the most vital criteria is the long-term performance which will vary depending on the type of waste contained. For instance, the NRC regulations require that a landfill of low-level waste should have a time frame performance of 500 years. On the other hand, high-level wastes which are contained in deep repositories (>500 m depth) should have a time frame of 10,000 years without affecting the biotic receptors. It is of prime importance to relay on a material that will have long term performance, such material is clay mineral which will have a very low hydraulic conductivity (10-10 m/sec) if it is well engineered.