peter witherington
TRANSCRIPT
Cover Systems and T f f S il B t SitTransfer of Soils Between Sites
Presented by:yPeter Witherington
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A cover systemy
A t i th i i f l t i l A cover system is the provision of clean material over contaminated ground
Thi i d th j it f b fi ld it This is used on the majority of brownfield site redevelopments
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What does a cover system do?y
Complete separation of receptor from hazard
OROR
Reduction in exposure
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The Research
The purpose of the research is to provideThe purpose of the research is to provide guidance on the design of cover systems. This research involved:
A questionnairet l t t ti
Literature survey
• to evaluate current practice
y
Garden Research• to establish cover degradation
Garden Research• to justify depth to undisturbed soil
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Summary of resultsy
Range of Cover Thicknesses for eachRespondent
Type
Range of Cover Thicknesses for each Contamination Category (mm)
Marginally Twice Most SevereMarginally Contaminated
Twice Guidance
Value
Most Severe Case
D l 300 1000 500 1000 1000Developers 300-1000 500-1000 1000
Consultants 0-1000 0-1250 500-30000 1000 0 1250 500 3000
Regulators 0-1000 0-1500 500-2000
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The question was asked
“What basis do you use for the d t i ti f thi k ”determination of cover thickness”
The answers were generally based upon
Experience Requirement of regulator Requirement of regulator
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Disturbance from earthworm activity
The main cause of disturbance of shallow soils
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Moles
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Rats and mice
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Rabbits and badgersg
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Disturbance from plant / tree roots
R t ff t d b
Disturbance from plant / tree roots
Soil Density
Roots are affected byy
Availability of nutrients
Availability of moisture
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Digging during gardening activities
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Location Plan
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Garden Geology Excavation Depth of Depth of Depth to Location
gyLocation
pTopsoil (mm)
pIntermixed layer (mm)
pUndisturbed Ground (mm)
Wareham, Dorset
Valley Gravel (possibly alluvium)
Mature lawn 0-270 270-480 480
Ch bh Bagshot Beds Mat re la n 0 450 450 650 650Chobham, Surrey
Bagshot Beds Mature lawn 0-450 450-650 650
London W4 Brickearth, River Terrace Deposits, London Clay
Newly dug last winter
0-220 220-580 580
B fi ld Gl i l S d d V t bl l t 0 300 300 310 310Beaconsfield Glacial Sand and Gravel
Vegetable plot 0-300 300-310 310
London NW9 London Clay Lawn 0-100/120 100/120-190/210
190/210-450*450
New Hinksey, Alluvium over Oxford Overgrown 0-350 350-400 400Oxford Clay flower bedSt Albans, Herts Valley Gravel Vegetable plot 0-310/430 310/430-450 380/450
Pembroke, West Wales
Carboniferous Limestone
Vegetable plot 0-250 250-450 450
Earls Barton, Northants
Northampton Sand Vegetable plot 0-280 280-480 480
Kidderminster Coal Measures Vegetable plot 0-240 240-540 540
Llangollen North Dinal Bran Beds Neglected flower 0 250 250 300/350 300/350
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Llangollen, North Wales
Dinal Bran Beds (Shales)
Neglected flower bed
0-250 250-300/350 300/350
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The Model - calculations
M = mixed zoneTv = Target guidance valueCc = contamination of cover (expressed as proportion of Tv)Cc = contamination of cover (expressed as proportion of Tv)Cg = contamination of ground (expressed as a multiple of Tv)X = capping thickness
T t t l ll ll bl t i ti lt f l t i t i i
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T = total overall allowable contamination as a result of complete intermixing(expressed as a proportion of Tv) = 1T = (X/M) (Cc) + ((M-X)/M) (Cg)X = M(Cg-1)/(Cg-Cc)
The model - plot
10.0
(1) For known level of contaminated ground and known cover contamination
p
8.0
9.0(1) For known level of contaminated ground and known cover contamination
Cover Contamination
6.0
7.0
0 x Trigger levels0.25 x Trigger levels0.5 x Trigger levels0.75 x Trigger levels
0
4.0
5.00
0.250.5
0.75
2.0
3.0
1.0300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600
Cover Thickness, X (mm), Required to Reduce Overall Contamination Concentration to Target Value (T
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The model - spreadsheet calculationp
Calculations based on mixed zone (M) 600mm
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Design Considerationsg
Suitability of cover system Suitability of cover system
Material cover used for cover system
Treatment of underlying material
Location of water table
Provision of capillary break layer
Provision of physical barrier at base of cover system
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Design Limitationsg
Presence of vapours or landfill gasses Presence of vapours or landfill gasses
Risk to controlled waters
Deep excavations for tree planting, ponds and foundations etc
Area of open space where rabbit populations are significant
Areas where badger sets are known to exist
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Th t th bit!That was the easy bit!
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T f f S il Th B k dTransfer of Soils – The Background
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The Definition of Waste
Waste Framework DirectiveDefinition of Waste?Definition of Waste?
….anything you discard, intend to discard or are required to discard.required to discard.
What does this mean?
Every bucket of excavated soil could be classified as waste
Potential Requirement for an Environmental Permit (formerly a Waste Management Licence) or an Exemption
Waste remains waste until it is fully recovered
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I guess already you feel like thisg y y
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What would you call this?y
A t ll it’Actually, it’s PROBABLY
waste!This is good
quality engineering
material!
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How about this?
This is useful backfill material!
This is changing
No it’s not, it’s DEFINITELY
waste!
backfill material!
g g
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What does this all mean?
HBF Figures:
UK construction is likely to be undertaking in excess of 70,000 activities
each year that should either be controlled by an Environmental Permit
(formerly a Waste Management Licence) or an exemption ………..
C tlConsequently
Probably every developer is working illegallyy y p g g y
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What does this all mean?
And should be in Jail?
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Change to the EA Positiong
Th D fi iti f W t D l i G fi ld d B fi ld itThe Definition of Waste: Developing Greenfield and Brownfield sitesEnvironment Agency – April 2006For both uncontaminated and contaminated soils EA indicatedFor both uncontaminated and contaminated soils EA indicated“….we may not consider it discarded, provided
i. they are suitable for that use and require no further treatmentii. only the quantity necessary for the specified works is used (otherwise it
becomes a disposal activity), andiii. their use is not a mere possibility but a certainty”iii. their use is not a mere possibility but a certainty
However the EA added a proviso“ . . . we refer to areas of work where the interaction between the Planning Authority and the Environment Agency need to be clarified. This interaction must be clarified before industry can take advantage of this position.”
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Revised EA Position
Definition of Waste: Development Industry Code of PracticeDefinition of Waste: Development Industry Code of Practice
Issued September 2008
“If materials are dealt with in accordance with the Code of Practice weIf materials are dealt with in accordance with the Code of Practice we consider that those materials are unlikely to be waste at the point when they are to be used for the purpose of development”
“The Code of Practice sets out a system whereby a declaration is sent to us by the Qualified Person. When the declaration demonstrates that the materials are to be dealt with in accordance with the Code of Practice, we ,will take the view that the materials on the site where they are to be used will not be waste”
The EA reser e the right to ithdra this position if the find that the CoP isThe EA reserve the right to withdraw this position if they find that the CoP is being misused.
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Th CL AIRE C d f P tiThe CL:AIRE Code of Practice
L h d S t b 2008 d t d 2011Launched September 2008 - updated 2011
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Basic Principlesp
“Materials are only considered to be waste if they are discarded, intended to be discarded or required to be discarded, by the holder. Once discarded, they remain waste until fully recovered. This remains the case even when the holder of the waste changes and the subsequent holder has a use for it”
In deciding whether or not material is discarded you should take into account of the aims and objectives of the Waste Framework Directive . . . The main aims of the of the WFD are the protection of Human Health and the Environment”
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Scopep
Voluntary and self regulating
England and Wales
Applies to contaminated and non contaminated material from natural and man made sources
Materials covered:Materials covered: Topsoil, sub-soil, parent material and underlying geology
Made groundg
Stockpiled excavated materials
Source segregated aggregate material from demolition
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Scopep
CCovers:
Excavated materials for use on site without or after on-site treatment during the development and remediation of land
Excavated materials treated at an authorised treatment facility and used in the development of landused in the development of land
e.g. authorised hub site within a defined cluster agreed by the EA and reused on a site within the cluster
Excavated clean, natural materials that go off site for use on another site Source segregated aggregate re-used on the site of origin
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Cluster project: a group of sites in close proximity that share a decontamination facility located on a single site – the Hub site.
Note!
N.B. The waste framework excludes:
“Uncontaminated soil and other naturally occurring material excavated in the course of construction activities where it is certain that the material will be used for the purposes of construction in its natural state on the site from which it was excavated.”
And therefore the CoP does not need to be applied in this situation.
So you can use topsoil on the site it is excavated without upsetting the European Courts!
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Caution!
The definition of waste is still a matter for the courts to decide!
Using the CoP does not void the requirement to adhere to current legislation, e.g.
Storage of waste on site and exemptions (N.B. changed in 2010)g p ( g )
Waste placed on or in land that has to be contained to prevent pollution or harm to human health is a landfill
Hazardous substances (previously List 1) must not reach groundwater Hazardous substances (previously List 1) must not reach groundwater
Note: The person commissioning the excavation works is responsible for complying with the CoP
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The four factors
The CoP relies on examining four factors (tests) relating to the re-use of materials
[1Protection of human health and protection of the environment][1Protection of human health and protection of the environment]
2 Suitability for Use (without further treatment)
3 Certainty of Use3 Certainty of Use
4 Quantity of Material
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The three scenarios
At present the CoP applies to three scenarios
1 Re-use of materials on the site where they were generated1.Re-use of materials on the site where they were generated
2.Re-use of natural materials on a site other than the site where they were
generated (i.e. direct transfer between sites)
3 Re-use of materials on multiple sites within a defined and authorised3.Re use of materials on multiple sites within a defined and authorised
‘cluster’
These require slightly different treatment
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Direct transfer - added 2011
Clean, naturally occurring soils only
Greenfield greenfield
Greenfield brownfield
Brownfield greenfield*
Brownfield brownfield*
*Must be soils from clearly defined areas of clean naturally occurring soils
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Lines of evidence
To justify compliance with the CoP it is necessary to provide lines of evidence confirming compliance with the three tests:
Suitable for use – without further treatmentSuitable for use without further treatment
Certainty of use
Quantity – that is absolutely necessaryQuantity that is absolutely necessary
ANDThe aims and objectives of the Waste Framework Directive are notThe aims and objectives of the Waste Framework Directive are not undermined Prevent harm to human health
Prevent pollution of the environment
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Materials Management Plang
Used to demonstrate compliance with the three testsUsed to demonstrate compliance with the three tests
Should form part of: A remediation strategy (contaminated sites) or A remediation strategy (contaminated sites) or,
A design statement (‘uncontaminated’ sites)
Must be followed throughout the works and include:
Details of how all materials in the ground will be dealt with.Details of how all materials in the ground will be dealt with.
A tracking system
Contingency statementsContingency statements
Qualified person’s declaration is signed once this has been developed.
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Qualified personsp
Demonstrably a competent and experienced person:y p p p Corporate authority – provided by employer Chartered – check status of registering body Relevant academic qualifications Relevant academic qualifications Minimum 5 years experience Currently engaged in planning, management or oversight of remediation projects or
projects involving site materials managementprojects involving site materials management Demonstrated by detailed CV
Not directly involved with the execution of the project (but can have been involved in earlier stages of site assessment)g ) Not barred – no convictions under waste or environmental legislation Training – (an EA Authorised Course) Registration not an EA requirement but: Registration – not an EA requirement but:
scheme set up by CL:AIRE requiring self declaration
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Qualified persons signed declarationp g
Signs off a “one pager” declaration prior to use (on site of production) or dispatch:
Code of Practice has been followed
Advises developer / contractor
If lines of evidence not fulfilled material is still considered wasteIf lines of evidence not fulfilled material is still considered waste
Verification Report has to be completed
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And what now?
Despite the current slow down in UK construction, there must be many hundreds of sites in the UK re-using soils since September 2008 that have not submitted declarations.
BUT the CoP is voluntary and hence it is not illegal to re-use soils without submitting a declaration.
How do you deal with the transfer of made ground and manufactured topsoils between sites?
Is it illegal?Is it illegal?
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What difference will the CoP make?
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