CONTAMINATION MANAGEMENT

Dr Adewale Abimbola, FHEA, GMICE

www.edulibrary.co.uk

Aim & Objectives

Aim: Contamination management

Objectives:

At the end of the lesson, the students should be able to:

• Describe the common contaminants in the UK and their impact on construction.
• Explain the different techniques of contamination management.

LO3 | P5 - Learning Outcomes and Assessment Criteria

Introduction

• Unregulated contamination arises from industrial, agricultural, and consumer activities.
• Soil and groundwater are at risk due to the build-up, spread, and harmful nature of contaminants.
• For a land to be contaminated, there must be a contaminant (or source), a pathway, and a receptor present at the site. When these three components are identified at a site, a pollutant linkage (PL) is said to be present (Fig. 1).
• Remediation stands as the sole effective method for purifying soil and groundwater contaminants.
• Managing contamination involves diverse strategies including physical, chemical, biological, and thermal methods.

What are the dangers posed by a contaminated land?

Figure 1. The source-pathway-receptor paradigm (Darmendrail et.al, 2002)

Introduction

• Elevated concentrations of contaminants in soil and groundwater indicate significant health and ecological dangers.
• Contaminants are categorised based on their nature: either Organic or Inorganic (Fig. 2).
• “Over 45,000 potentially contaminated land sites in Wales are not being fully inspected. Only 82 sites in Wales are designated as contaminated” (Friends of the Earth, 2025).
• Remediation approaches encompass relocating contaminants or affected soil/groundwater for treatment/disposal, containing them on-site, or destroying contaminants in their existing location.

Figure 2. The main contaminant groups found on contaminated sites in the UK. (Defra UK, 2010).

Figure 3. Contaminant categories on which the determinations of contaminated land sites were based (Environmental agency, 2009).

Pollution of Ground Water

• Groundwater Contamination Sources: How?
• Agricultural chemicals like pesticides, herbicides, and fertilizers seep into groundwater through soil leaching caused by rain or irrigation.
• Pollutants from urban landfills infiltrate groundwater sources due to rainwater leaching.
• Heavy metals (e.g., mercury, lead, chromium) and household chemicals concentrated beneath dumps can pollute groundwater.
• Waste from septic systems, sewage plants, and animal facilities, containing harmful microbes, can lead to groundwater contamination.
• Acidic discharge from coal and metal mining operations contaminates both surface and groundwater.
• Shallow burial of low-level radioactive waste from the nuclear industry can lead to groundwater pollution.

Land Contamination

Causes of Land Contamination?

• Tank and pipe leaks and spillages.
• Incidents or leakages while transporting or storing raw materials, products, and waste.
• Waste material disposal on-site or nearby.
• Contamination of the environment from stack emissions.
• Demolishing structures containing pollutants (like asbestos or impregnated brickwork).
• Contaminated groundwater encroaching onto the site.
• Toxic or explosive gas migration from neighbouring areas or subterranean layers.
• Leakage from drainage systems.

Land Contamination

Potential Land Contamination Scenarios?

• Previously used industrial sites, especially from chemical, pharmaceutical, oil refining, and storage sectors.
• Rural areas with improper spreading of sludge or contaminants.
• Regions with naturally occurring hazardous substances, like radon, ground gases, or high levels of metal elements.
• Sites affected by illegal dumping, cable burning, and bonfires.

Corby (in Northamptonshire) Toxic Waste Scandal: �Case study of environmental negligence and community justice

• Steelworks Closure & Cleanup (1980s): After the closure of Corby's steelworks, toxic waste from demolition was moved in uncovered lorries, spreading dust and contamination.
• Millions of tonnes of toxic waste relocated to Deene Quarry.
• Local families reported a rise in birth defects (limb deformities) among children.
• 2009: Families won a landmark High Court case against Corby Borough Council.
• Legal significance: First UK ruling acknowledging airborne contamination harming unborn babies.
• Importance of environmental monitoring in redevelopment projects.
• Ethical responsibility of local authorities in public health protection.

Sulphates & Other Site Contaminants

• Sulphates often occur in ground fill, especially on brownfield sites reclaimed from industrial use (e.g., former collieries/coal mines, steelworks).
• If high-sulphate hardcore is used beneath concrete floors, sulphate attack can degrade concrete, causing swelling, cracking, and structural damage.
• Example:
• Widespread sulphate attack on 1970s housing in the English Midlands due to use of colliery spoil (mine spoil/minestone) as fill led to floor slab failure and costly repair programmes.

Other Site Contaminants

• Asbestos, heavy metals (lead, arsenic), oils, tars, and construction dust may also be encountered, especially on urban redevelopment sites.
• Discovery of buried drums or unexpected tanks can halt works for investigation and safe removal.

Land Contamination

How do you determine whether land could be contaminated?

• Local authorities’ own survey information: Part II Environmental Protection Act 1990: a public contaminated land register and contaminated land inspection strategy, updated every 5 years.
• Public Health of England has published reports containing radon Affected Area maps for the whole of the United Kingdom.

https://www.youtube.com/watch?v=8NFfM5zZBnA&feature=emb_logo

• Local planning authority records, including historic environment and relevant Environmental Statements.
• Natural England’s MAGIC site which sets out information about the environmental setting and sensitivity of the development site.

Land Contamination

How do you determine whether land could be contaminated?

• Information about previous land uses by the Natural Resources Wales ,and Environmental agency.
• National Land Use Database.
• Historic landfill sites.

Figure 4. Contaminated area determinations reported by local authority (Natural Resources Wales, 2016)

The classification of remediation technologies in the UK.

• In situ – Remedial activities taking place in the subsurface.

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• Ex situ – Remedial actions applied to excavated soil or the treatment at surface of contaminated water or gaseous emissions.

Table 1. Remediation techniques (Defra UK, 2010)

Group-assessment Task - Case Study�(10 minutes)

Refer to the attached ‘Phase 3 Remediation Verification Strategy’ file’ and briefly identify/highlight the following points:

1) What is the scope of the project?

2) What is the pollutant linkage?

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3) The mitigation strategies and potential remediation techniques to be integrated into the development?

4) The possible outcomes of remediation and mitigation for the site?

Cut-Off Wall (COW) Techniques for Containment

• A cement-bentonite or soil-bentonite Cut-Off Wall (COW) is used to enclose contaminated groundwaters/soils or divert water from these areas to reduce human and ecological exposure and prevent further contamination.
• The primary goal is to create a low-permeability or impermeable barrier affordably.
• The COW serves as a barrier, enabling various constructions within its perimeter, which can extend to hundreds of meters.
• In cases where bentonite is incompatible with the waste, attapulgite, a magnesium aluminium phyllosilicate found in clay soil, is used.
• Recent advancements include the use of fly ash as a high carbon additive to enhance the soil-bentonite’s permeability reduction and organic chemical adsorption capacity.
• https://www.youtube.com/watch?v=_NHhapkoUYk

Encapsulation Methods for Contaminant Isolation

• This method effectively quarantines contaminants, separating them from the soil.
• A frequent approach involves mixing polluted soil with lime, cement, or concrete.
• Encapsulation is particularly advantageous when removal or off-site disposal of contaminants is impractical or not cost-effective.
• Key Goals in Encapsulation Cell Design and Construction:
• Aim to minimise water infiltration into the encapsulation cell.
• Ensure the structural integrity of the cell over an extended period with minimal maintenance requirements.
• Design should account for potential future land use and redevelopment, while maintaining the cell's integrity and effectiveness.

• Utilisation of reactive barriers, both permeable and semi-permeable, is a common encapsulation technique.
• Contaminants, upon encountering these barriers, undergo adsorption, transforming into harmless solid compounds within the barrier.

https://www.youtube.com/watch?v=zSHr-PrtfKM

Figure 5. Schematic representation of permeable reactive barrier (U.S. EPA, 1998)

Contamination Management

• Bioremediation is a process where microorganisms are used to degrade certain contaminants, transforming them in-situ into different substances.
• This method is particularly effective in reducing hydrocarbon levels in soil, often decreasing concentrations to about 1/50th of their original levels with minimal disturbance to the site.
• Advantages of Bioremediation:
• The process transforms contaminants into environmentally safer substances, reducing reliance on external waste disposal facilities.
• This transformation minimises both direct and indirect environmental impacts associated with waste disposal.
• Limitations of Bioremediation:
• Bioremediation is typically a slow process, often taking more than a year to complete.
• The technique is mainly effective for organic contaminants and may not be suitable for all types of pollution.

https://www.youtube.com/watch?v=6hrctQfAWyg

https://www.youtube.com/watch?v=XB3p39wS87M

Contamination Management

• Chemical Oxidation (Chemox) is a process that oxidises contaminants to lower their concentrations.
• It is effective for treating a range of organic contaminants, including Total Petroleum Hydrocarbons (TPH), BTEX (Benzene, Toluene, Ethylbenzene, Xylenes), and Polychlorinated Biphenyls (PCBs).

Benefits of Chemox:

• Allows for in-situ treatment of contaminated soil and water, including areas that are hard to access.
• The method is applicable even in challenging locations such as soils under buildings or at significant depths.

Application Method:

• Chemicals, oxidising or reducing agents (such as Ozone (O3), Calcium Peroxide [CaO2], etc.), are injected into contaminated materials using lances under pressure.
• This technique ensures that treatment is possible wherever a drill rig can reach.

https://www.youtube.com/watch?v=2iATMtoEkYs

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Other: Thermal remediation: https://www.youtube.com/watch?v=Jb2CS4VMJfM

Self-assessment Task �(20 minutes)

Describe at least any TWO techniques used for remediating a site prior to construction commencing.

Note:

• A paragraph of about 5-6 lines for each of the technique.
• You must use illustration to support your description.
• Ensure you provide the sources (intext citations and references) of the information.

References/Bibliography

• Darmendrail, D., Bardos, P., Harris, R. and Grimski, D. (2002) Darmendrail, D. & Bardos, Paul & Harris, Robert & Grimski, Detlef & kasamas, harald & Lowe, Malcolm & Bieber, Andreas & Büsing, Jürgen & Crawford, Rae & Crommentuijn, Trudie & Dock, Lennard & Quercia, Francesca & Schamann, Martin & Veenn, Johan & Vegter, Joop. (2002). Sustainable management of contaminated land: an overview. 10.13140/RG.2.2.20348.03204.
• Defra UK (2010) Contaminated Land Remediation. Available at: https://www.google.com/search?q=Defra+Research+Project+Final+Report&rlz=1C1AVSK_enGB691GB691&oq=Defra+Research+Project+Final+Report&aqs=chrome..69i57.467j0j9&sourceid=chrome&ie=UTF-8 (Accessed: 20 July 2021).
• Environmental Agency (2009) Dealing with contaminated land in England and Wales. Available at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/313964/geho0109bpha-e-e.pdf (Accessed: 20 January 2023).
• Friends of the Earth (2025) Over 45,000 potentially contaminated land sites across Wales. Available at: https://friendsoftheearth.uk/nature/over-45000-potentially-contaminated-land-sites-across-wales (Accessed: 17 January 2026).
• National Resource Wales (2016) The state of contaminated land in Wales. Available at: https://naturalresources.wales/media/677708/nrw26759-contaminated-land-in-wales-pdf_english-1.pdf (Accessed: 21 January 2023).
• U.S. Environmental Protection Agency (1998) Permeable reactive barrier technologies for contaminant remediation. EPA/600/R-98/125. Washington, D. C.
• Welsh Government (2016) Environmental statement supplement volume 3: appendix R11.2 outline remediation strategy report. Available at: https://www.gov.wales/sites/default/files/publications/2017-10/m4-corridor-around-newport-environmental-statement-supplement-appendix-r11.2-outline-remediation-strategy.pdf (Accessed: 21 January 2023).

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