LANDFILL DIRECTIVE ENGINEERING REQUIREMENTS

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LANDFILL DIRECTIVE ENGINEERING REQUIREMENTS
RGN 11 STABILITY

• RICHARD MOSS
• ENVIRONMENT AGENCY
• ESA - 25 NOVEMBER 2002

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RGN 11 DISPOSAL IN NON-HAZARDOUS SITES OF

• STABLE, NON-REACTIVE HAZARDOUS WASTES
• ASBESTOS WASTES
• HIGH SULPHATE/ GYPSUM WASTES

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REGULATION 10 (3) (4)

• Where stable, non-reactive hazardous waste is
  disposed of at a non-hazardous landfillensure it
  is not deposited in cells used for biodegradable
  waste
• special measures in expected European Council
  Decision

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STABLE, NON-REACTIVE HAZARDOUS WASTE MEANS...

• leaching behaviour of the waste will not change
  adversely in the long-term under the landfill
  design conditions
• in the waste alone (for example, by
  biodegradation)
• under the impact of long-term ambient conditions
  (for example, water, air, temperature or
  mechanical constraints) or
• by the impact of other wastes (including waste
  products such as leachate or gas).

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NOTE HAZARD IS STILL PRESENT

• DIFFERS FROM STABILISED, WHERE HAZARD IS REMOVED
• TREATMENT IS NOT REVERSIBLE

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LIKELY WASTE TYPES

• Monolithic solidified wastes e.g. large blocky -
  mixed with cement/pfa
• Guidance on limit values due in future
• Granular treated wastes e.g. filter cakes
  treated fly ash
• Limit values included in guidance (may change)

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CELL SEPARATION PRINCIPLES

• no direct physical contact between stable,
  non-reactive hazardous wastes and biodegradable
• no contact between leachate or gas
• separate leachate collection and extraction
  systems
• separate landfill gas collection and extraction
  systems where required
• operation of cells must not compromise management
  separate cells
• account for these principles for the long-term.

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2 OPTIONS

• engineered cell separation
• barrier connecting basal liner to surface sealing
• managed placement of waste
• barrier constructed using waste

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Figure 1 Engineered Separation of Cells
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Figure 2 Managed Cell Separation by Segregated
Waste Placement
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NO PIGGYBACKING because...

• problems in ensuring integrity of cell separation
• barriers within waste body cause management
  problems

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FUNCTIONAL CELL SEPARATION REQUIRES STABILTY
INTEGRITY

• Cell separation principles must be assured for
  the long-term

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P1-385 STABILITY OF LANDFILL LINING SYSTEMS

• Stability Assessment has higher profile as it is
  an explicit requirement of the PPC Landfill
  Permit
• Report to be published by WRc imminently

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Landfill Regulations Schedule 2

• 6 - (1) The placement of waste must ensure
  stability of all the waste on the site and
  associated structures and in particular must
  avoid slippages
• (2) Where an artificial barrier is used, the
  geological substratum must be sufficiently
  stable, taking account the morphology of the
  landfill, to prevent settlement that may cause
  damage to the barrier

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INTEGRITY IS AS IMPORTANT AS STABILITY

• Integrity failure leads to unpredictable barrier
  performance invalidates hydrogeological risk
  assessment

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DESIGN SHOULD TAKE ACCOUNT OF STABILITY
INTEGRITY

• Use site-specific test data
• Account for both short-term (including
  construction) and long-term
• Monitor conformance and performance

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WHAT DOES THIS MEAN FOR FUTURE?

• Step-change in design practice
• Most current design is limited doesnt consider
  integrity - predict strains
• Need for monitoring of stresses and strains