Developing land potentially affected by contamination

Land Contamination is a legacy of historical industrial activity and past waste disposal practices. In some instances, substances and waste materials from these activities may have caused pollution to the ground.

This contamination has the potential to cause harm to human health, ground and surface waters, ecological systems and the built environment.

The presence of contamination does not necessarily present an unacceptable risk. Development can create risk by introducing new pathways and by introducing new receptors.

Where development introduces a particularly sensitive use, such as houses with gardens, schools, or allotments, the possibility of land contamination should always be considered.

The presence, or possible presence, of contamination is an important factor when the Council considers planning applications. We must make sure that any development does not create, or allow the continuation of, unacceptable risks.

This includes making sure the site is safe for its new use and does not pollute the wider environment.

Applicants should carry out a risk assessment before submitting a planning application.

If land is known or likely to be affected by contamination due to past uses, the planning application must include a Phase 1 study.

This should consist of:

• a desktop study of the site and its history
• a site walkover
• a preliminary risk assessment

Applications without this information may be considered invalid.

A Phase 1 study is the minimum requirement. Applicants are encouraged to contact the Planning team and Environmental Protection before submitting an application to discuss site-specific issues.

Please note that pre-application advice may incur a charge.

Where significant contamination is known or suspected, further investigation and risk assessment may be needed before the Council can make a decision. Applications may be refused if insufficient information is provided and if there is a potential unacceptable risk.

All investigations should follow the Land Contamination Risk Management (LCRM) guidance.

All site assessments must be carried out by experienced and competent professionals, usually consultants or specialists. They must be familiar with modern site investigation techniques, risk assessment methods, and current UK policy and legislation on land affected by contamination.

The National Planning Policy Framework Section 196 (c) requires that adequate site investigation information, prepared by a competent person, is provided to inform planning decisions.

See the examples below of potentially contaminated sites:

• metal processing and finishing
• gasworks
• petrol stations
• tanneries
• manufacture of chemicals including paints, fertilisers
• timber treatment
• landfill sites
• scrap yards
• abattoirs
• railway or road haulage depots
• engineering works
• agriculture

There will be circumstances in which the past use of the land or buildings suggests the possibility of contamination. Examples might include buildings previously used for light industrial purposes or for agricultural use.

In cases where the risk is very small or the risks are understood and there is a remediation option, we may impose a conditions on any grant of planning permission.

The conditions would ensure that the site is investigated and any necessary remediation is carried out before or during development.

Conditions may also be used where we are satisfied that the risks are understood and that there is a remedial option, but where not all the details have been resolved.

The standard for cleaning up land through the planning process is that, at a minimum, the site should not be capable of being designated as Contaminated Land under Part IIA of the Environmental Protection Act 1990.

This guidance does not cover remediation under Part IIA, although the information requested for planning purposes is often very similar.

Section 196(b) of the National Planning Policy Framework (NPPF) states that, after remediation, land should meet this minimum standard.

Applicants should also be aware that Building Regulations approval may be required. The Building Control Officer must be informed of any contamination issues to ensure all relevant requirements are met.

Site characterisation and risk assessment should be carried out in phases:

• Phase 1 assessment is mainly a desk-based study of the site, its history, and potential contamination risks
• Phase 2 assessment involves intrusive investigation of the site, if Phase 1 indicates contamination may be present

The aim of these investigations is to assess risks to existing and future users of the site, and to other environmental receptors.

If unacceptable risks are found, remedial work will be needed to reduce or remove them.

All investigations must be carried out by experienced and competent professionals, usually consultants or specialists. West Northamptonshire Council cannot recommend specific consultants or contractors. You can find lists of suitably qualified professionals in trade directories, telephone directories, or through professional institution websites.

The Phase 1 assessment should consist of a desk study, site walkover, conceptual site model and a preliminary risk assessment. The desk study comprises a search of available environmental information and historical maps, which can be used to identify the likelihood of contamination.

A simple walkover survey of the site should be conducted to identify pollution linkages not obvious from the desk study.

The Phase 1 assessment should include:

• detailed site plan showing the site location, extent and boundary
• site walkover information including description of condition of structures, soils and vegetation
• referenced photographs taken during the site walkover
• geographical setting of site including geology, hydrology and hydrogeology
• review of current and historical maps for site and surrounding area
• previous, present and proposed uses of the site and adjacent land
• previous and current industrial processes carried out on site including environmental permits
• details of pollution incidents or spillages
• information on waste management and disposal practices including landfill sites
• details of water abstractions, discharge consents, drainage and services
• information on any mining, extraction or infilling activities
• a review of any previous desk studie or site investigations
• initial sampling of soils, water and gas where appropriate
• an awareness of all potential on and off site receptors

From the findings of this work, a preliminary conceptual site model will be developed for the site. This will normally be in the form of a table or schematic diagram illustrating any potentially significant sources of contamination, pathways through which contaminants can travel and receptors that eventually could be harmed.

The preliminary risk assessment and conclusions derived from the conceptual site model will indicate whether a Phase 2 contamination assessment (intrusive site investigation and risk assessment) is required.

The Phase 1 assessment should be submitted as a written report to the local authority prior to commencement of a Phase 2 investigation, as the local authority or Environment Agency may require further information or clarification of issues.

Various companies offer a database generated desk study type report (e.g. Envirocheck, Sitescope, Groundsure and Homecheck). It is acceptable for these kinds of reports to be included as part of a Phase 1 assessment.

However, such reports submitted in isolation will be inadequate. Local authority Environmental Protection and Planning departments are also very useful sources of local, environmental information for desk study purposes.

Therefore, it is advisable to contact the relevant departments to see if they hold any records relating to potential contamination issues with a particular site. Please note that there may be a charge for the provision of such environmental information.

Phase 1 - Summary

1. Research site history to establish if previous uses could have led to contamination.
2. Obtain as much information of the previous uses and potential contaminants as possible to highlight which areas of the site could be affected (including adjoining land where such risks exist). Ask Environmental Protection for directions to any further land contamination guidance that the Council may have.
3. Identify who and what is a risk (example: future occupants, buildings and environment) and the potential pathways for those risks – known as the Conceptual Site Model.
4. Submit a Phase I Preliminary Risk Assessment when submitting the application. If required, discuss findings with relevant authorities.
5. The Planning Authority will then decide if the submitted report is to be accepted and whether there is a need to proceed to the next stage.

Phase 2 - Intrusive site investigation

Phase 2 assessment consists of an intrusive site investigation and risk assessment. The investigation process should seek to confirm potential pollutant linkages at the site to allow refinement of the preliminary conceptual site model.

The data obtained will be used to inform a decision as to whether the site is potentially harmful and if remedial works are required to mitigate any risks from contamination present.

All sampling strategies should be designed to provide data that is representative of the site conditions as a whole. Sampling should be undertaken in accordance with recognised sample collection methodology and guidance.

Following completion of the investigation, analysis results need to be compared against suitable assessment criteria. Soil sample contaminant concentrations should be compared to industry accepted generic assessment criteria that has been developed to be protective of human health. Other risk assessment tools might also be acceptable, but their use must be fully justified and conform to current UK policy.

The Environment Agency’s ‘Remedial Targets Methodology – Hydrogeological Risk Assessment for Land Contamination guidance should be used for assessing contamination risks to ground and surface waters.

The first step of the assessment is to compare water and leachate samples to the appropriate environmental water quality standards. If more detailed assessment is required, it is recommended that the Environment Agency are consulted.

Following completion of the investigation, a Phase 2 risk assessment detailing the investigation methodologies used, results, conclusions and recommendations should  be submitted to the local authority for approval.

The report should include:

• rationalisation for sampling locations including reference to desk study findings
• sampling techniques used
• plans of sampling locations
• borehole and trial pit logs
• groundwater and ground gas monitoring where applicable
• copies of laboratory analysis certificates
• discussion of ground, groundwater and gas conditions and any contamination encountered
• qualitative and quantitative risk assessments including comparison of analytical results with appropriate assessment criteria
• refinement of the conceptual model and preliminary risk assessment
• discussion of any uncertainties in relation to the conclusions
• recommendations for further investigation (if required) and remedial options

If the Phase 2 assessment shows that there are unacceptable risks from contamination to human health, property or the wider environment, then remediation will be required.

Phase 2 - Summary

1. Using information from Phase 1 assessment, the applicant will need to undertake initial intrusive investigation. Note monitoring for substances such as ground gas can take several months.
2. Review Conceptual Site Model.
3. Decide which risk assessment criteria is appropriate or needs to be developed. Submit a report to Planning Services. If required, discuss findings with Environmental Protection and the Environment Agency.
4. Planning Services will decide if the submitted report is to be approved and if there is a need to proceed to next stage.

A remediation strategy is a document detailing what action is to be carried out so that contamination no longer presents a risk to human health, property, the environment or ecological systems.

As part of the production of the remediation strategy, a remedial options appraisal should be performed.

The report should include details on how the remedial works will be validated to ensure that the remedial objectives have been met.

The strategy must be submitted to and approved by the local authority prior to the commencement of remedial works at the site.

Remediation must be carried out in accordance with the agreed strategy. Any deviation from it or unexpected contamination discovered during site works needs to be immediately reported to the local authority.

Any necessary additional investigation, risk assessment or remedial works will need to be approved by the local authority.

Following completion of remediation works, the developer will be required to submit a verification report to enable Planning Services to discharge any planning conditions.

The verification report should provide confirmation that all measures outlined in the approved remediation strategy have been successfully completed, including where appropriate, validation testing.

The report should include:

• a summary of the works carried out and the risks that have been managed
• validation sampling of any imported soils, including details of the source of material and appropriate analysis
• all laboratory and in-situ test results and, if applicable, monitoring results for groundwater and ground gas
• photographic and other media records
• certification of any gas protection measures installed in individual buildings
• confirmation that the remediation objectives have been met