Contaminated Land

Contaminated land refers to areas of soil, groundwater, or sediment that have been polluted by harmful substances due to industrial activities, natural sources, or other human interventions. These contaminants may be chemical, biological, or radioactive and can pose risks to health and the environment if not managed effectively.

In the UK, addressing contaminated land is essential for sustainable development, particularly as the government encourages the reuse of brownfield sites under the National Planning Policy Framework (NPPF).

Ensuring that development on contaminated land is safe is the responsibility of the developer, landowner or both. According to the Planning Portal: “Where a site is affected by contamination or land stability issues, responsibility for securing a safe development rests with the developer and/or landowner” (Paragraph 197, NPPF). This highlights the importance of understanding, assessing, and remediating contamination risks before commencing any development project.

What causes land contamination?

Land contamination can arise from various sources, including:

• Industrial activities: Historical industrial operations such as factories, mines, and landfills often leave behind harmful substances like heavy metals, radioactive substances, oils, and organic compounds.
• Natural sources: Underlying rock formations can sometimes release contaminants such as radon gas or heavy metals into the soil.
• Agricultural practices: Pesticides, fertilisers, and waste disposal can introduce pollutants into the land.
• Brownfield sites: Previously developed land may still harbour residual contaminants from its prior use.

Why is land contamination a concern?

New development on sites with land affected by contamination can create risk to future occupants by exposing the contamination. The development work may create new pathways for the contamination and introduce new receptors that can be adversely affected by contamination such as a person or controlled waters.

The risks posed by contaminated land depend on three key elements:

1. Source: The presence of contaminants at harmful concentrations.
2. Pathway: A means for the contaminants to reach humans or the environment, such as via ingestion, inhalation, or skin contact.
3. Receptor: The individuals, ecosystems, or environments exposed to the contaminants.

If one of these elements is missing, the risk is significantly reduced. For example, heavily contaminated land that is inaccessible to the public poses minimal threat.

Assessing risk from contaminated land

Identifying contamination on a site does not necessarily mean it will pose an unacceptable risk. The significance of risk will vary according to the site’s history and the type of development proposed. To fully understand the risk, a land contamination risk assessment will be required. While this will be a key factor in the development scheme, it is rare for a contaminated land report to completely prevent a development from proceeding.

Failing to follow statutory guidance to address any contamination issue correctly on the land affected could cause harm to human health and the environment.

The role of the planning process

The NPPF emphasises sustainable development and encourages the remediation of contaminated land to make it safe for reuse. For any development site suspected of contamination, the local planning authority must be satisfied that the risks are understood and mitigated before granting planning permission. Developers are required to provide detailed information, often in the form of a land contamination risk assessment, to demonstrate that:

• The contamination issue has been thoroughly investigated.
• The proposed development will not pose unacceptable risks.
• Any necessary remediation is viable and practical.

Land contamination risk assessment

Assessing contamination risks involves several stages as determined by a series of guidelines, namely the Environment Agency’s LCRM (Land contamination risk management (LCRM) – GOV.UK):

1. Desk study: A review of historical records, maps, and previous land uses to identify potential contamination sources.
2. Site walkover: An on-site inspection to observe signs of contamination or land instability.
3. Soil and groundwater testing: Sampling and laboratory analysis to determine the presence and concentration of contaminants.
4. Risk analysis: Evaluating the likelihood and potential impact of contaminants on receptors.

If risks are identified, a remediation plan must be developed and submitted to the local planning authority. This plan outlines the measures required to make the site safe for its intended use and for future occupants.

The role of a geo-environmental consultant in contaminated land assessment

A competent geo-environmental consultant plays a crucial role in assessing and managing contaminated land. These specialists bring technical expertise to evaluate the geotechnical and environmental conditions of a site. Their responsibilities often include:

• Site investigations: Conducting comprehensive surveys to identify contamination sources, pathways, and receptors.
• Risk assessments: Analysing data to determine the level of risk posed by contaminants.
• Remediation design: Developing practical solutions to address contamination, such as soil treatment, removal, or containment strategies.
• Compliance with regulations: Ensuring all assessments and remediation efforts meet legal requirements and standards.
• Monitoring and validation: Overseeing the remediation process and verifying that the development site meets safety criteria post-remediation.

By working closely with developers and the enforcing authority, geo-environmental consultants help ensure that contaminated sites are safely redeveloped, reducing potential risks to health and the environment.

Engaging a competent person, as defined by the NPPF, to devise an inspection strategy detailing all the necessary information offers several benefits, including:

• Reducing the chance of objections to your planning application.
• Helping the local planning authority to process your application efficiently, minimising delays.
• Allowing the local planning authority to tailor conditions related to land contamination, reducing unnecessary requirements.
• Lowering the risk of delays from adverse environmental searches during property sales.
• Ensuring the health of future occupants of the site is protected from contamination risks.
• Minimising potential future liabilities related to land contamination.

Legal framework for contaminated land

In England and Wales, the management of contaminated land is governed by the Environmental Protection Act 1990. Under this legislation, local authorities are required to:

• Identify and inspect potentially contaminated sites.
• Determine whether a site poses a significant risk to human or environmental health.
• Ensure appropriate remediation measures are taken.

Land is classified into four categories based on risk levels:

1. Category 1: High risk requiring immediate action.
2. Category 2: Evidence of potential risk requiring remediation.
3. Category 3: Low or uncertain risk; regulatory action may not be required.
4. Category 4: No risk or acceptable levels of risk.

Addressing contamination through remediation

Remediation aims to reduce or eliminate risks associated with contaminated land. Common remediation techniques include:

• Excavation and removal: Contaminated soil is removed and replaced with clean soil.
• Soil treatment: Contaminants are neutralised or removed through physical, chemical, or biological methods.
• Capping: A barrier, such as a layer of clean soil or concrete, is placed over contaminated areas to prevent exposure.
• Groundwater treatment: Contaminated water is treated on-site or extracted for off-site treatment.

Why develop land potentially affected by contamination?

A presumption in favour of sustainable development lies at the heart of the National Planning Policy Framework (NPPF), which states that planning policies and decisions should support the use of suitable brownfield land for housebuilding and other development. According to the NPPF, the purpose of the planning system is to achieve sustainable development which is viable and deliverable. The reuse of brownfield sites aligns with the UK’s commitment to reducing urban sprawl and preserving greenfield land.

Balancing risks and opportunities

With proper assessment and remediation, land affected by contamination can be transformed into safe, useable areas. While contaminated land can present challenges, it also offers opportunities for regeneration and sustainable development.

By understanding the sources, risks, and remediation options, developers, landowners, and local authorities can work together to ensure safe and sustainable land use. The involvement of geo-environmental consultants adds a layer of expertise that helps navigate complex regulations and legal implications. With careful planning and collaboration, even the most challenging sites can be successfully redeveloped, contributing to a cleaner and more sustainable future.