An introduction to ReCon Soil Liz Gray, Senior Managing Consultant, Ramboll

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ReCon Soil
Liz Gray

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What is the problem?
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UK Recycling
and other
recovery
Backfilling Landfill
All waste -
2016 103.9 16.8 52.3
2018 108.4 14.2 50.8
Change 4.3% -15.8% -2.8%
million tonnes and % change
Waste material
Mineral
wastes
55% 6% 6%
Soils 12% = 13m
t
90% = 12.8
m t
58% =
29.5m t
Dredging
spoils
0% 1% 0%

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Soil Organic Carbon pool stores est. 1,500,000 megatons C in the first meter of soil > carbon contained
in the atmosphere (~ 800,000 megatons) & terrestrial vegetation (500,000 megatons) combined (FAO
and ITPS, 2015)
In the first three meters of the soils an even larger carbon mass of up to 2,344,000 megatons C are estimated.
Emissions from the aviation
sector, soil carbon stocks
and the potential of soil
carbon sequestration to
offset carbon.
(UN FAO - Soils Potential to
Contribute to Offset Int’l
Aviation Emissions 2017)

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“The time needed to form a soil depends on the
latitude:
• in environments characterized by a mild climate, it
takes 200-400 years to form 1 cm of soil
• in wet tropical areas soil formation is faster, as it
takes 200 years
• in order to accumulate enough substances to make
a soil fertile it takes 3000 years.”
http://www.eniscuola.net/en/argomento/soil/soil-
formation/how-long-does-it-take-to-form/
“Essentially, soil can be considered as a non-
renewable resource, as the formation of topsoil
and the recovery of soil (and groundwater) quality
are extremely slow processes. ...It should be
acknowledged here that soil is a scarce natural
resources and an inseparable part of the soil-water-
sediment-system.”
A.M. Breure et al. Science of the Total Environment
624 (2018) 1125-1130
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Soil is a finite resource

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Industry challenges
• Circular Economy
• Move from problem to resource
• Keeping soils in the chain of utility
• Pushing soils up the waste hierarchy
• Maintaining the intrinsic value of soils
• Topsoil
• Supply issues (geographically and temporally)
• Quality
• Long term storage often required – restoration of agricultural land
Fig 1. Established reconstructed soil at the Eden Project, Cornwall,UK.

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Industry challenges
• Biodiversity Net Gain (BNG)
• Environment Act 2021 – 10% BNG on development sites
• Good biodiversity on brownfield sites with unique habitats – range of
soil quality required
• Net Zero Carbon by 2050
• Build back greener
• Key focus on new Nationally Significant Infrastructure Projects
• Organisations are looking to use ‘spare’ land (e.g. road verges) to off
set carbon through activities such as tree planting.
Fig 1. Established reconstructed soil at the Eden Project, Cornwall,UK.

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Barriers and challenges
Fig 2. Example soil constituents.
• Regulatory – complex and default to worst-case: waste
• Organisational practices – project planning, finance models
• Materials quality
• Public perception – safety, environmental risk, land value

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What is ReCon Soil?
•Reconstructed soils from waste
• Soils constructed from waste materials have already
been demonstrated to be capable of supporting plant
growth and nutrient cycling.
• €2.5m Interreg (Channel Manche) Project.
• Started January 2021, ends June 2023.

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Aims of ReCon Soil
1)Reduce the quantity of soils sent to landfill by the construction
sector using a circular economy approach.
2)Reduce pressure on natural soils and their associated carbon stocks
through the development application-specific soil ‘recipes’ to
reduce the need for translocation of natural soils.
3)Contribute to increased soil carbon capture through the
incorporation of components capable of long-term carbon storage.

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• Key example reconstructed soil components
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What’s in a soil recipe?
Inorganic components Organic components Mixed components
• Aggregate (e.g. gravel, sand,
clay)
• Fly ash
• Volcanic rock (e.g. basalt,
perlite, tuff)
• Composted green waste
• Wood substrate
• Composted bark
• Manure
• Natural soils
• Biosolids
• Dredged sediments
• Biochar
Fig 2. Example soil constituents.
To ensure the long-term sustainability of reconstructed
soils recipes will be needed that account for
• The required soil properties for the intended application
• Local material availability.

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Applications for reconstructed soils
• Landscaping soils
• Structural/engineering soils
• Recreational facilities
• Land restoration and rehabilitation
• Controlled growing facilities – vegetable growth
• Remediation

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How can ReCon Soil help industry?
• Make it easier for industry to do a good job in relation to soils
restoration.
• Expand meeting BNG obligations beyond nominal planting.
• Increase opportunity for projects to achieve better carbon
management on site.
• Address issues of agricultural land restoration.
• Increased awareness – Low Carbon Networks

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• Networking evening in Exeter City Centre to celebrate the work
of ReCon Soil, hosted by CL:AIRE.
• Hear early developments from industry-leading research
• Celebrate a shared interest in sustainable soil remediation
• ReCon Soil (claire.co.uk)in/e5CXkHV4
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World Soil Day – 5th December

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Liz Gray
Liz.gray@ramboll.com