Secure landfilling.pptx

everything about secure landfilling along with some examples as well as some criteria of developing such landfills specially in case of hazardous waste

1. Hazardous SWM Secure landfilling Drishti S hrestha

2. What’s secure landfill? A secure landfill is a carefully engineered disposal facility where hazardous waste is placed in or on land and that is designed, constructed and operated to prevent any pollution from being caused by the facility outside the area of the facility. secure landfill  means a landfill that utilizes a liner system, a leachate collection and treatment system, and a final cover system to minimize discharges of waste or leachate, and control the release of gas, to the environment. Metropolitan area landfill The metropolitan area landfill has been treating wastes from Seoul, Incheon , and Gyeonggi Province since 1992. It is now completely closed and has been turned into a golf course and park, and has been transformed into a resting place for citizens.

3. Why secure landfill ? Hazardous wastes are wastes other than radioactive wastes which by reason of their chemical reactivity toxic, explosive, corrosive or other characteristics causing danger or likely to cause danger to health or environment, whether alone or when coming into contact with other wastes, are legally defined as hazardous in state in which they are generated or disposed of through their transport.

4. Contd.. Due to their toxicity, persistent, mobility, flammability, they require more stringent, regulatory and technical controls compared to other waste. Hence, secure landfill are especially designed and operated to protect the public health and environment from hazards of hazardous wastes .

5. Design of secure landfill The levels of safeguard that must be incorporated into the design of a hazardous landfill which are :- Liner system-an impermeable liner, either of clay or synthetic material , A leachate collection and treatment system Gas collection and treatment facility Fina l cover Surface drainage system Environmental monitoring plan Closure and post closure plan

6. Research and testing of the range of synthetic liners must be viewed with respect to a liner's strength, compatibility with wastes, costs, and life expectancy. Rubber , asphalt, concrete, and a variety of plastics are available, and combinations such as polyvinyl chloride (PVC) and high density polyethylene (HDPE) overlaying clay may prove useful on a site-specific basis. Liner system

7. Why liner system? Infiltration may be minimized with a cap of impervious material overlaying the landfill, sloped to permit adequate runoff and discourage pooling of water .  to prevent groundwater and soil contamination The objectives are to prevent rainwater and snow melt from entering the soil and percolating to the waste containers and, if water does enter the disposal cells, to collect and treat it as quickly as possible.

8. Leachate collection and treatment facility A leachate collection system  designed to promote movement of the waste to pumps for extraction to the surface and subsequent treatment. Plastic pipes, or sand and gravel are adequate to channel the leachate to a pumping station below the landfill. One or more pumps direct the collected leachate to the surface, where a wide range of waste specific treatment technologies are available, including: Sorbent material  carbon and fly ash arranged in a column through which the leachate is passed. Packaged physical-chemical units  including chemical addition and flash mixing, controlled flocculation, sedimentation, pressure filtration, pH adjustment, and reverse osmosis.

9. All methods produce waste sludge that must reach ultimate disposal . A secondary safeguard system consists of another barrier contoured to provide a backup leachate collection system. In the event of failure of the primary system, the secondary collection system conveys the leachate to a pumping station, which in turn relays the wastewater to the surface for treatment.

10. Leak detection system The system must consist of both up gradient and down gradient wells which allow sampling of the groundwater in the uppermost aquifer,. The samples from the upgradient wells show the background concentrations of constituents in the groundwater, while the downgradient wells show the extent of groundwater contamination caused by the HSW

11. Gas collection and treatment facility If methane generation is possible in a hazardous waste landfill, a gas collection system must be designed. Sufficient vent points must be allowed so that the methane generated may be burned off continuously.

12. Final cover Final cover  is a multilayered system of various materials which are primarily used to reduce the amount of  storm water  that will enter a  landfill  after closing. Proper final cover systems will also minimize the  surface water  on the liner system, resist  erosion  due to wind or runoff, control the migrations of  landfill gases , and improve aesthetics. A final cover system can include a top soil layer composed of nutrient rich soil, a protective layer to reduce the effects of freeze/thaw, a drainage layer which moves storm water, a barrier layer, and a grading layer.

13. A surface water drainage system - which collects and removes all surface runoff from the landfill site. An environmental monitoring system - which periodically collects and analyses air, surface water, soil-gas and ground water samples around the landfill site. A closure and post-closure plan -which lists the steps that must be taken to close and secure a landfill site once the filling operation has been completed and the activities for long-term monitoring, operation and maintenance of the completed landfill.

14. Operation of secure landfill As waste containers are brought to a landfill site for burial, specific precautions should be taken to ensure the protection of public health, worker safety, and the environment. Wastes should be segregated by physical and chemical characteristics, and buried in the same cells of the landfill. Three dimensional mapping of the site is useful for future mining of these cells for recovery purposes . Observation wells with continuous monitoring should be maintained, and regular core soil samples should be taken around the perimeter of the site to verify the integrity of the liner materials.

15. Site closure Once a site is closed and does not accept any more waste its operation and maintenance must continue . The impervious cap on top of the landfill must be inspected and maintained to minimize infiltration Surface water runoff must be managed, collected, and possibly treated. Continuous monitoring of surface water, groundwater, and soil and air quality is necessary, as ballooning and rupture of the cover material may occur if gases produced or released from the waste rise to the surface . Waste inventories and burial maps must be maintained for future land use and waste reclamation. A major component of post closure management is maintaining limited access to the area.