Contaminated Land Inspection Strategy 2024 to 2029

Definition of Contaminated Land

The EPA 1990 [Section 78A (2) of Part 2A of the Environmental Protection Act 1990] provides the definition of contaminated land as:

Any land which appears to the local authority, in whose area it is situated, to be in such a condition, by reason of substances in, on or under the land that -

• (a)  significant harm is being caused or there is a significant possibility of such harm being caused
• (b)  significant pollution of controlled waters is being caused, or there is a significant possibility of such pollution being caused

To be determined as Part 2A contaminated land there must be a 'Significant Contaminant Linkage' or significant possibility of such a linkage. The potential for harm is assessed using a tiered risk assessment approach using the scientific evidence available, and the local authority should be satisfied, that on the balance of probabilities, that significant harm is being caused by a particular contaminant.

Pollution of controlled waters

The contaminated land strategy includes pollution of "controlled waters" and includes rivers, coastal waters, inland freshwaters, and groundwater. This is defined in Part 3 of The Water Resources Act 1991, with the exception that "ground waters" do not include waters contained in underground strata, thereby including strata above the saturation zone.

The pollution of controlled waters is defined as "the entry into controlled waters of any poisonous, noxious or polluting matter or any solid waste matter." [Section 78A (9) of Part 2A of the Environmental Protection Act 1990] the following types of pollution should be considered to constitute significant pollution of controlled waters: 

• (a) pollution equivalent to "environmental damage" to surface water or groundwater as defined by The Environmental Damage (Prevention and Remediation) Regulations 2015 but cannot be dealt with under those regulations
• (b) inputs resulting in deterioration of the quality of water abstracted, or intended to be used in the future, for human consumption such that additional treatment would be required to enable that use
• (c) a breach of a statutory surface water Environment Quality Standard, either directly or via a groundwater pathway
• (d) input of a substance into groundwater resulting in a significant and sustained upward trend in concentration of contaminants (as defined in Article 2(3) of the Groundwater Daughter Directive (2006/118/EC)

Pollution linkages

For any land to be identified as contaminated land at least one contaminant linkage needs to be established. All three elements of a contaminant linkage must exist for land to be considered as 'contaminated' with evidence of the presence of contamination.

• (a) a "contaminant" source is a substance which is in, on or under the land and which has the potential to cause harm to a relevant receptor, or to cause pollution of controlled waters
• (b) a "pathway" is a route by which a receptor is or might be affected by a contaminant
• (c) a "receptor" is something that could be adversely affected by a contaminant, for example, a person, an organism, an ecosystem, property, or controlled waters

Where a connection is identified, developing a Conceptual Site Model is a fundamental aspect of understanding the linkage. This involves a written or schematic description of the specific site features, the contaminants of concern and the risks posed to receptors.

Determining what constitutes a "significant contaminant linkage" can be an extremely complex process. Stockton-on-Tees Borough Council will make its decision based on the best available evidence at the time of the investigation and on an individual site basis. Consideration may be given to the number of people who might be exposed to the risk and the scale of the seriousness of harm.

Inspection process

The current best practice methodology for detailed investigations is specified by the Environment Agency is the Land Contamination Risk Management (LCRM) Guidance (Environment Agency, updated Jul 2023). The guidance specifies various procedures, practices, methodology, stages of the process and acceptable British Standards, as well as other guidance documents which can be used.

The staged process commences with a strategic preliminary inspection which is informed by the collection of desk-based information and a site walkover, possibly with limited soil and or water sampling. Where this strategic preliminary risk assessment suggests that further understanding of the risks is required, a more detailed site inspection is then carried out.

Detailed site inspection commences with a generic quantitative risk assessment whereby detailed information on the ground conditions is collected to further develop the site conceptual model through gaining a more thorough understanding of the risks and uncertainties involved.

Depending on the findings of the generic quantitative risk assessment it may become necessary to carry out various further stages of more detailed risk assessment to support a decision as to whether a site meets the definition of contaminated land under Part 2A.

Following completion of the detailed site investigation and risk assessment, the analyses derived from the sampling will be used to complete a Detailed Quantitative Risk Assessment (DQRA), the outcome of which is used as an indicator of the possibility of harm.

During the detailed inspection process, the Council will seek to gain voluntary cooperation with the owner or occupier of the land. It is beneficial to establish this early, particularly should further works and remediation be necessary. If there is nation or the owner of the land cannot be found, the Council should then consider using their statutory powers of entry under section 108 of the Environment Act 1995.

Risk evaluation criteria for human health

For human health, the findings of detailed inspections of soil will be compared against generic and site-specific assessment criteria, generated using the most up to date version of CLEA UK Model (Contaminated Land Exposure Assessment). The evaluation criteria to assess the risks are derived using generic assumptions about the characteristics and behaviour of contaminants, the pathways, and the exposed population. The model derives generic land use scenarios to derive Soil Guideline Values (SGV) using health criteria values which are associated with minimal risk.

Contaminants in ground water and surface water, will be assessed for their risk to human health, by comparing to the UK Drinking Water Standards (DWS) and environmental quality standards. For controlled waters, hydrogeological risk assessment guidance tools will be used to protect the aquatic environment (Environment Agency, LCRM, July 2023).

In terms of ecological assessment, the most up to date guidance on the use of soil screening values in ecological risk assessment will be used, such as soil screening values proposed by the Environment Agency (January 2022) "Derivation and Use of Soil Screening Values for Assessing Ecological Risks."

In March 2014, DEFRA published guidance on the derivation and use of Category 4 Screening Levels (C4SL). This produced levels for specific contaminants (Arsenic, Benzene, Benzo(a)pyrene, Cadmium, Chromium (VI) and Lead), for six common land use types, for which the statutory definition of Contaminated Land under Part 2A had not been met and provides guidance to determine the most appropriate risk category.

Normal levels of contaminants

The statutory guidance states that the Part 2A regime should not apply to land with levels of contaminants in soil that are commonplace and widespread throughout England and for which in most cases there is no reason to consider that there is an unacceptable risk. 

Technical Guidance Sheets on Normal Background Levels of Contaminants in English Soils (Defra, October 2012) was commissioned to support the revised Statutory Guidance in evaluating whether land is contaminated. Normal levels of contaminants in soil may be the result of the natural presence of contaminants or the presence of contaminants caused by low level diffuse pollution, and common human activities other than past industrial uses. 

Procedure for determining land as Contaminated Land under Part 2A 

Following strategic preliminary inspections, Stockton-on-Tees Borough Council may be able to place some sites within Category 4 where no relevant contaminant linkage exists. Further risk assessment may be necessary for other sites to place them into Categories 1 to 3.

The Statutory Guidance states that where all factors are considered, if the local authority cannot decide whether a significant possibility of significant harm exists, it should conclude that the legal test has not been met and the land shall be placed in Category 3.

Following completion of a detailed site investigation and risk assessment, the site conceptual model will be updated to show whether one or more significant contaminant linkages exist or otherwise. Where one or more significant contaminant linkages exist between any sources of contamination and relevant receptors under Part 2A, the Environmental Protection Team will follow the procedure for determining that land as contaminated land, as set out in Section 78A (2) of the Environmental Protection Act 1990 and the revised Statutory Guidance and the land will be placed in either Category 1 or Category 2.

Stockton-on-Tees Borough Council may decide to defer the determination of contaminated land after informing interested parties because the landowner or other interested person may choose to undertake the remediation on a voluntary basis, and to an appropriate standard and timescale, agreed with the Environmental Protection Team.

The determination may also be postponed should one or more significant contaminant linkages only exist if the circumstances of the land were to change in the future within the bounds of the current use of the land.

Stockton-on-Tees Borough Council may reconsider a determination if new information comes to light, which is significant enough to alter the original decision. In such cases, Stockton-on-Tees Borough Council will decide whether to retain, vary or revoke the determination. The determination may also be postponed should one or more significant contaminant linkages only exist if the circumstances of the land were to change in the future within the bounds of the current use of the land.

Risk categories for sites investigated under Part 2A

The Statutory Guidance (Defra 2012) introduced 4 risk assessment categories for sites investigated under Part 2A.

Table 3 summary of risk categories

Designating special sites

Local Authorities have been given the primary regulatory role under S.78B (1) Part 2A of the Environmental Protection Act 1990 for determining whether any land within their borough is contaminated and for deciding whether any such land should be designated as a special site.

If Stockton-on-Tees Borough Council identifies land which it considers would be likely to meet one or more of the descriptions of a special site set out in the Contaminated Land (England) Regulations 2006, it should consult the Environment Agency and subject to the Agency's advice and agreement, to arrange for the Agency to carry out any intrusive investigations of the land on behalf of the authority. 

The 4 main groups are cases consisting of:

1. water pollution - wholesomeness of drinking water, surface water classification criteria, major acquifers
2. industrial sites - waste acid tar lagoons, oil refining, explosives, sites regulated under the Integrated Pollution Control Regulations which have become contaminated
3. defence
4. radioactivity

Where the agency carries out an inspection on behalf of Stockton-on-Tees Borough Council, the inspection duty, and the decision as to whether land is contaminated land, remain the sole responsibility of the Council.

Where decisions are not straightforward, and where there may be unavoidable uncertainty underlying some of the facts of each case, consideration shall be given to.

• alternative means of dealing with associated risks to human health and the environment
• the benefits to human health and the environment of remediating land to remove or reduce those risks (including the taxpayer where relevant)
• the potential impacts of regulatory intervention including the financial costs to whoever will pay for remediation, property blight, and burdens on affected people
• a precautionary approach shall be undertaken to the risks raised by contamination, whilst avoiding a disproportionate approach given the circumstances of the case
• part 2A determination shall only be considered where no appropriate alternative solution exists and other legislative means to address contaminated land have been considered

Written statements

The Statutory Guidance (2012) requires written statements to be issued by the local authority stating the land is not considered to be contaminated under the legislation to minimise unwarranted blight.

In such cases, the Council will issue a Written Statement to that effect (rather than coming to no formal conclusion). The Council will consider making Written Statements available to other interested parties proactively and will always provide Written Statements on request.

Remediation

The enforcing authority for the purposes of remediation may be the local authority which determined the land, or the Environment Agency, which takes on responsibility once land has been determined if the land is deemed to be a "special site". Once a site has been determined as contaminated land, Stockton-on-Tees Borough Council will have regard to the Statutory Guidance and relevant technical documents in deciding what remediation action shall be taken. In doing so the Authority may also consult with a suitably qualified experienced practitioner.

In deciding what is reasonable, the authority must consider:

(a) the practicability, effectiveness, and durability of remediation

(b) the health and environmental impacts of the chosen remedial options

(c) the financial cost which is likely to be involved

(d) the benefits of remediation regarding the seriousness of the harm or pollution of controlled waters in question

Prior to determination, the Authority will issue a risk summary explaining why the land is considered contaminated and outline the remediation required. Voluntary action to deal with contaminated land will be encouraged as far as it is considered reasonable and practicable. In doing so, a broader approach and other legislation will be utilised as part of wider regeneration work.

If Voluntary Remediation cannot be agreed or additional information has not been provided to that would require a review of the determination notice, the Authority will issue a Remediation Notice to the "appropriate person." The Remediation Notice will provide details of the remediation required.

Liability

The factors to consider in establishing the liability for remediation set out in the Guidance, imposes liability in respect of actions done in the past which may not have given rise to liabilities as the law stood at the time the pollution occurred.

This is apportioned to parties defined legally as persons. When identifying appropriate persons, each significant contaminant linkage is treated separately (unless it is reasonable to treat more than one linkage together because the same parties are liable).

Section 78F of the legislation defines who may be an "appropriate person," for example, a person is liable if they "caused or knowingly permitted" the contaminating substance(s) "to be in, on or under" the land in question. If no such person, "after reasonable inquiry", can be found, the responsibility for remediation falls to the owner or occupier of the land.

The statutory guidance specifies various classes of persons who are liable for the cost of remediation, as outlined below.

Table 4 Classes of persons liable for remediation costs

Due to the various exclusion tests outlined in the statutory guidance, it is important to note that identifying the appropriate person can be a lengthy process. Additionally, sites may have an extensive historic succession of land ownership and different components of a contaminated site may be attributable to different polluters, over different periods of time.