A Contractor’s Perspective on Redeveloping Historical Landfills

A CONTRACTOR’S
PERSPECTIVE ON
REDEVELOPING
HISTORICAL LANDFILLS
Andy O’Dea
Technical Director
Cognition Land & Water
cognitionlandandwater.com

CONTENTS
A BIT ABOUT ME
A BIT ABOUT COGNITION
THE ISSUE
KEY CHALLENGES
PROJECT EXAMPLES
WHERE NEXT?

ABOUT
US

• Andy O’Dea – Technical Director
• Civil Engineering / Soil Mechanics & Environmental Geotechnics
• CEnv, MIEnvSc, FGS, AMICE, QP(DoWCoP)
• 30 years consultancy and contracting experience
• Sustainable land development and infrastructure
• Specialities:
• Contamination risk assessment and remediation
• Waste management
• Soil gas risk
• Geotechnical design
A BIT
ABOUT ME

A BIT
ABOUT
COGNITON
• Contamination remediation and ground engineering contractor
• Established 2005
• Carbon neutral since 2021
• 50 technical/management staff, 100 site staff
• Engineers, chemists, geologists, environmentalists, ex-regulators
• Typical project values from £500K to £30M
• Minimise soil disposal and maximise reuse
• Remediated and redeveloped over about 15 landfill sites

THE
ISSUE

THE
ISSUE
• Waste regulation is prohibitively
complex and time consuming!
• Landfills are full of black bag waste
that can’t be safely processed or
reused!
• DoWCoP shouldn’t be used for
landfill restoration!
• Recovery Permit is the best way
forward for landfill redevelopment!
LET’S DO
SOME
DEBUNKING!

SO
WHAT?
• Processing or reuse of soil within a
site may be a ‘waste’ activity
• All ‘waste’ activities require an
environmental permit or exemption
• EA revised position on application of
DoWCoP to landfills and stockpiles
• Try to avoid it becoming a ‘waste’ in
the first place
RESULT
Thousands of waste management
offences are unwittingly committed
every year on UK construction sites
Millions of tonnes of soil are
unnecessarily disposed to landfill

Material is only
considered to be waste if
it is discarded, intended
to be discarded or
required to be discarded
by the holder
Therefore,
‘waste’ is not
directly related
to chemical
composition,
value or
potential for
reuse
LEGAL
DEFINITION
OF WASTE

WHAT SHOULD I DO?

• Introduced in 2008, revised in 2011 (V2)
• Approved and supported by the EA
• Unlikely to be ‘waste’ based on four key principles
1. Protection of human health and the environment
2. Suitable for use without further treatment
3. Certainty of use
4. Quantity - only use what you need
• Three scenarios
1. Reuse on site of origin
2. Direct transfer (clean, naturally occurring soil)
3. Cluster projects
REDUCE - DoWCoP

KEY
CHALLENGES

“The Environment Agency considers
that: ‘any material that consists of
current or historically landfilled
waste remains waste on excavation
and therefore cannot be used under
DoWCoP”
KEY
CHALLENGES
“Exclusion of landfill seems
arbitrary and hinders sustainable
materialsmanagement for no
economic,social or environmental
benefit”

• Revised position that DoWCoP not applicable to landfill
• Waste legislation and regulation not suited to construction soils
• Trying to shoehorn soil reuse into Environmental Permit system
• A lack of pragmatism or understanding of the issues
• Lack of clear guidance and conflicting opinions
• DoWCoP being undermined despite being the best solution we have
• Underfunded regulator - backlog of permit applications
• DoWCoP is not broken - Please let’s not lose its value
• We need V3 ASAP to deliver Defra EIP, i.e. soil = resource ≠ waste!
KEY
CHALLENGES

SHAMELESS PLUG…
CIRIA GUIDANCE
• Sustainable Management of Surplus Soil
and Aggregates from Construction
• Cognition Land and Water funding and on
the Project Steering Group
• Promotes and simplifies opportunities to
sustainably reuse surplus site soils
• Detailed, user-friendly, up to date,
interactive guidance
• Covers the whole surplus soil
management process from ‘cradle to
grave’

• Past application of DoWCoP -
Hawkenbury Farm
• Current position due to revised EA
position - Klondyke Industrial
Estate
• Some exceptions allowing use of
DoWCoP - Newbury and Burgess
Hill
• Where we are heading -
Confidential site
LANDFILL DEVELOPMENT
Examples

• Former clay pits, landfilled 1930-1960s
• Up to 5.5m of mainly soil with some
ceramic, brick, wood, metal, fabric
• Hydrocarbon contamination impacting
watercourses
• Remediation required to treat
hydrocarbons
• Geotechnical improvements required to
make it suitable for redevelopment
HAWKENBURY FARM
Background

• Excavation, screening, segregation of landfill upper
layers
• Bioremediation of hydrocarbon hotspots
• Ground improvement through rolling dynamic
compaction and placement of processed fill
• Permeable reactive barrier
• Cement stabilisation of site won soils for pile mats
• Treated soils reused under a DoWCoP MMP
(8,000m3)
• Wider site earthworks cut and fill under MMP
(35,000m3)
• Landfill cover soils validated and reused as clean
cover system for soft landscaping
HAWKENBURY FARM
Remediation Works

• Use of DoWCoP fully approved by QP,
CLAIRE, LPA and EA in advance
• Highly sustainable project
• Problematic site returned to beneficial use
• Remedial solution made project financially
viable
• Minimal offsite disposal
• Carbon emission savings
• Reduced vehicle movement
• Improved groundwater quality
• New homes & school for community
HAWKENBURY FARM
Outcome

• Remediation and earthworks for Homes
England on 32 acres
• Remediation of made ground and landfill,
installation of PVDs, cover layer and surcharge
• Recovery Permit to allow reuse of treated
‘waste’ soils (9 months!)
• Capping and surcharge soils imported under
DoWCoP (55,000m3)
• Processing and reuse of 450,000m3 of soils
• Still a question over future reuse of surcharge
soils!
KLONDYKE
ISLE OF SHEPPY

• Ground improvement and remediation
• 157 new homes with gardens and POS
• Former quarry, landfilled, capped and restored
• No groundwater remediation required
• Waste Disposal Licence 1981 - revoked 1991
• Originally looked to get Deposit for Recovery
Permit. Timescales made this impossible!
• Three types of soil/materials present:
• Topsoil
• Capping soils
• Landfill
NEWBURY
Background

• TOPSOIL - Original topsoil strip -
uncontaminated and suitable for reuse -
NOT WASTE (Reuse onsite under DoWCoP)
• CAPPING - Clean quarry overburden placed
as >1m thick landfill cap. Restoration soil,
not discarded - NOT WASTE (Reuse onsite
under DoWCoP)
• LANDFILL - Typically 4m thick. Mainly soils
with limited wastes. Only present in
deeper excavations for services - WASTE
(Disposal to landfill)
NEWBURY
Materials and Waste Regulation

• 3.26Ha disused brickfield
• 36 new homes with gardens & POS
• Up to 3.6m of made ground fill over
Weald Clay
• Historical quarry reclamation with
construction and demolition fill
• Low groundwater risk
• Contamination hot spots and
potential for collapse settlement
BURGESS HILL
Background

• Excavation of upper layer of made ground - sort,
process, stabilise for geotechnical improvement
• Dispose waste materials - Reuse processed soils
• Groundwater control and treatment in excavations
• Ground improvement using RDC of deeper fill
• Re-engineering of processed fill
• Groundwater monitoring during and following works
• Gas protection measures in buildings
• Clean cover system in private gardens and soft
landscaping (site won topsoil)
• Verification of the clean cover systems
BURGESS HILL
Remediation Solution

• Detailed discussion and negotiation with
EA for approval
• Site was never a ‘landfill’, never licensed
and only restoration soils
• Made ground processed under Cognition’s
Mobile Plant Permit
• Processed soils reused under DoWCoP
• Deleterious materials disposed offsite
• Contamination hot spots removed from
site
BURGESS HILL
Waste Regulation

• Part of former gravel pit from 1924
• Landfill - inert construction, household and
industrial waste up to 1974
• Surface capped with 1.3m clean cover and topsoil
• Various ongoing issues such as asbestos at the
ground surface, potential impact on Chalk
aquifer, ground gas on neighbouring housing
• Site needs to be remediated and planning
process is only viable solution
CONFIDENTIAL
Deposit for Recovery?

• Proposed remediation solution:
• Controlled removal of upper waste layers and hotspots
• Careful management and monitoring of groundwater
• Rolling dynamic compaction of lower fill
• Processing re-engineering quarry fill
• Cover layer in private gardens and soft landscaping
• Reduce contaminant mass and source of landfill gases
• Reduce infiltration into the Chalk aquifer
• DoWCoP unlikely under current EA position… why not?
• Deposit for Recovery Environmental Permit… impossible
timescale and no guarantee it will be granted
• Question - Is this ‘new’ approach viable or sustainable?
CONFIDENTIAL
Deposit for Recovery?

WHERE
NEXT?

• Treat each site on its merits - screen out non-problem sites early
• Awareness raising / training
• Lobby EA / DEFRA / OEP
• Maintain DoWCoP to include landfilled and stockpiled soils
• Post Brexit - redefine classification of waste under UK legislation
• Understand from EA why they are suddenly requiring permits on
construction sites - what’s changed?
• New bespoke simpler waste recovery permit?
• Hope and pray for logic and pragmatism to prevail!
WHERE NEXT?

QUESTIONS?
ANDY O’DEA
MSc BAI BA DIC CEnv MIEnvSc FGS AMICE QP(DoWCoP)
Technical Director – Cognition Land and Water
andy.odea@cognitionltd.com
M: 07833 873 065
Harwell Innovation Centre
Harwell Campus
Curie Avenue
Didcot
OX11 0QG
T: 03333 494 400

THANK
YOU

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