Conservation and Recovery Act of 1976 prohibited open dumping, therefore making it illegal in many states. Sanitary landfill A sanitary landfill is where waste is disposed of in thin layers little by little; each layer is covered and compacted with soil to prevent foul odors and wind blown litter. This method prevents the creation of safety and public health hazards; this landfill has four requirements before it is built. The first requirement is that it must have absolute leachate security; the bottom of the landfill can be lined, synthetically or with soil, to prevent water contamination. Secondly, there must be formal engineering preparations and planning in order to ensure the success of the landfill. Thirdly, permanent supervision must be present in all stages of the landfill also to ensure success and sustainability. Lastly, the placement and compacting of waste must be planned to prevent pest and vermin infestations. Secure landfill A secure landfill is where hazardous waste is deposited since it requires a much more stringent regulation than municipal waste. The landfill must have at least two impermeable liners as well as a system for leachate collection to prevent any water contamination. In addition to this, the landfill must also have a groundwater monitoring system in case there is a leak; the wells can be pumped to remove the contaminated water for treatment. Deep-well injection Deep-well injection is a form of disposing of liquid hazardous waste. The liquid waste is pumped into porous limestone or sandstone through a steel casing, and high pressure is applied in order to permanently store the waste within the pores and fissures of the rocks. The limestone or sandstone used for injection must be located beneath an impermeable layer of clay or rock at least 0.5 mile below the surface. This option generally does not require pre-treatment of the waste and is one of the more inexpensive options, however it poses a risk of hazardous waste leakage. Legislation United States California The California Integrated Waste Management Act mandated all Californian cities and counties to divert 25% of their solid waste by 1990 and 50% by 2000 through planning and programs; this is managed by the California Department of Resources Recycling and Recovery (CalRecycle), and they also provide assistance in creating plans and programs. The percentage of solid waste required to be diverted has remained at 50% each year. Maryland The Maryland Department of the Environment