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 Shrestha

2. What’s secure landfill?
o 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.
o 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
→ Final cover
→ Surface drainage system
→ Environmental monitoring plan
→ Closure and post closure plan

7. »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

8. 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.

9. 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:
a. Sorbent material  carbon and fly ash arranged in a column through which
the leachate is passed.
b. Packaged physical-chemical units  including chemical addition and flash
mixing, controlled flocculation, sedimentation, pressure filtration, pH
adjustment, and reverse osmosis.

11. • 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.

12. 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

13. 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.

15. 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.

16. • 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.

17. 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.

18. 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.