By,

R. Denis, D. Tan, G. Élie and D. Cao

Solmax International

Waste Management 2012

10th Annual Waste Management and Conference

“Wastes to Opportunities”

18-19th July 2012, Kuala Lumpur, Malaysia

Landfilling at LargeSingle and Double Lined Basal SystemsLandfill ClosureTemporary ClosureMechanically Stabilized Perimeter Berms Solar Panel Landfill CapsBiorectorsLandfill Mining

Presentation Topics

Landfilling at Large

Domestic and industrial wastes are a necessary evil. We need to apply ways and methods to reduce them to a minimum through responsible choices such as efficient processes, biodegradable options and recycling. But for the foreseeable future there will always remain a fair percentage of wastes which need to be somehow addressed properly.

Some modern solutions involve "discarding" them altogether such as plasma conversion (currently very small-scaled and requiring large capitalizations) and incineration (relatively expensive, potential air polluting and hazardous ashes).

But it is not the wastes themselves that pollute the

environment !, it’s the medium of transports which spread the wastes all over the environment, such as wind action, malevolence and especially water from precipitations

that forms leachates, and carries pollutants afterwards through the smallest cracks!..

Burying eliminates both wind and malevolence actions, while proper landfilling eliminates runaway leachates.

Landfill will be safe when dry-toombed i.e. when all leachate will have been removed at the end of consolidation.

Proper landfilling does not eliminate wastes, but it takes away all of their mediums of transport!

In similar fashion to the penitentiary system, proper landfilling does not "eliminate" the prisoners, but all

of their transport options have been taken away while under severe watch! And some prisoners may

even be eventually rehabilitated (think of landfill mining for instance)!

Hence the familiar expression;

“Waste Management”

While efficient and secure, waste management may also be considered as an interim solution

to future viable technologies

Single Lined Basal SystemLandfilling will thus require hydraulic barriers for imperviousness. While natural soil barriers may be contemplated, geosynthetic barriers offer the highest security;

Chemically inertLong lastingHomogeneous and continuous revetmentEngineered properties and improved designs (all constraints covered)AvailabilityHighest impermeabilitySpace saving from reduced excavation and typical cross-sectionsAccelerated constructionEfficient leachate and biogas captorsExhaustive quantitative documentationEnhanced qualityReduced carbon footprint

Geomembrane (GM)

Typical Single-Lined Basal System

Aggregate or Synthetic Drainage

Geotextile

Typical Single-Lined Composite Basal System

Geosynthetic Clay Liner (GCL)Compacted Clay

Liner (CCL)

Type 1 Type 2

Geotextile

Aggregate or Synthetic

Geomembrane (GM)

Compacted Clay Liner (CCL)

Summary of 62 Country and States Survey(ref. Geosynthetic Research Institute, 2007)

AustraliaAustriaBrazilCanadaChina (HK)CroatiaCzech RepublicDenmarkFinlandFranceGermanyHong KongHungary

IrelandItalyJapanNew ZealandPolandPortugalSouth AfricaSpainSwedenTaiwanUnited KingdomUnited States

Countries include;

• 65% require a GM/CCL composite basal liner for hazardous waste landfills

• 62% require a GM/CCL composite basal liner for municipal waste landfills

• 21% require double lined facilities for hazardouswaste landfills

• 8% require double lined facilities for municipalwaste landfills

Whenever GM’s are required, HDPE is unanimous

Double Lining Basal System

But no hydraulic barrier is fully impervious in spite of the most stringent QA and QC!!!

"… So let’s put two hydraulic barriers together and make it a Double-Lined System!... “

WRONG!!!

If you have reasons to believe that a primary barrier may leak (and you should), you should

have the same reasons to believe that a secondary barrier may leak as well!

Therefore, the secondary barrier in a Double-Lined System is definitely not

there in case the primary barrier leaks!

γh

γh=0

If efficient pumping is performed, no hydrostatic pressure will act on secondary barrier, hence

perhaps a little wet under it…but no flow across secondary barrier!

Primary Barrier

Secondary Barrier

Gravity Exit or EfficientPumping

Hydrostatic Head is Nil

Back Pressure or Non-efficient Pumping

Hydrostatic Head is building up, vertical gradient forms.

Efficient Drainage Roofing Analogy

The 2nd inner bottle is not there in case the first outer bottle breaks! Both bottles work together to contain the insulating medium!

The 2nd inside window is not there in case the first outside window breaks! Both windows work together to contain the insulating medium!

Compacted Clay Liner

Geomembrane (secondary)

Geocomposite (drainage)

Geomembrane (primary)

Aggregate Drainage Layer

Geotextile (anti-puncture)

Geotextile (separation)

Waste

Typical Double-Lined Composite Basal System

GM/CCL

Landfill Closure

Leachate formation need to be halted

Consolidation need to be addressed

Biogases need to be addressed

Erosion protection need to be addressed

Porous Venting Layer

Geomembrane

Geotextile (anti-puncture)

Waste

Aggregate Drainage Layer

Vegetative Cover

Typical waste landfill cover system

Geotextile (separation)

Summary of Survey continued…

• 44% require a GM/CCL composite cover liner for hazardous waste landfills

• 8% require a GM/CCL composite cover liner for municipal waste landfills while 65% require a CCL liner alone!

CCL liner alone is a practice that is becoming frowned upon particularly for municipal waste

landfills on account of cracking from differential settlements and clay desiccation

impairing biogas efficient collection.

PiggybackingDesigned to improve waste capacity of an existing landfills without additional land occupation

Temporary Closure

Also designed to improve waste capacity of an

existing landfills without additional land occupation

Use of a temporary (sacrificial) exposed geomembrane cover that harmoniously blends with green environment. Additional vertical waste space provided following consolidation

Perimeter berms with the use of mechanically stabilized earth (MSE) berms consisting of compacted earth reinforced with geosynthetic layers. MSE berms may also create capacity by allowing the landfill to be built higher.

Spectral Power Cap combines four 250-kilowatt arrays covering 10 acres into a total operating capacity of 1 Mw, enough to power 224 homes. Best of all, the system makes money for the landfill operators through an agreement with Georgia Power to sell the energy into the wholesale electricity market.

No mowing costsNo fertilizing costsNo erosion control costsReduced carbon footprint

Bioreactor

Accelerated dry-tombingAccelerated consolidationEarlier additional waste capacityMaximisation of Biogas productionEarly stage of biogas productionLower waste and leachate toxicityReduced leachate treatment costsWaste water and sludge outletReduced post-closure costs

Necessity to insure high level of impermeability (double-lined) under adverse leachate volumes

and hydrostatic heads

Increased odors

Physical instability of waste mass due to increased moisture and density

Potential instability of liner systems

Increased exothermia and landfill fire risks

Increased polymer ageing rate

R&D stage (gathering info)

Landfill Mining

Easier recycling (separation, sorting and screening) of " overs" after consolidation of organics.

"Unders" may be placed in new landfill cell or used as daily cover

Conclusion

Modern engineered landfills represent the most cost effective and secured technology today. It also enables the storage of recyclables which would otherwise be incinerated.

The application of geosynthetics in landfill designs has resulted in significant savings in construction costs, space savings, as well as reductions in carbon footprints.

Geosynthics are allowing bolder and sustainable landfill designs, by efficiently preventing percolation of contaminants as well ascollecting 99% of biogas.

Landfill geosynthetic designs constitute a World-wide proven technology.