The Importance of a Quality Land Contamination Assessment

The availability of land is one of the biggest barriers to building at the moment. The lack of available land, and the necessity of avoiding development on greenfield sites to ensure sustainable development, has meant that brownfield sites have become increasingly popular in recent years, especially in places where demand for residential and commercial property is high.

The National Planning Policy Framework (NPPF) defines previously developed land (PDL, or brownfield land) as:

‘Land which is or was occupied by a permanent structure, including the curtilage of the developed land (although it should not be assumed that the whole of the curtilage should be developed) and any associated fixed surface infrastructure.

‘This excludes: land that is or has been occupied by agricultural or forestry buildings; land that has been developed for minerals extraction or waste disposal by landfill purposes where provision for restoration has been made through development control procedures; land in built-up areas such as private residential gardens, parks, recreation grounds and allotments; and land that was previously-developed but where the remains of the permanent structure or fixed surface structure have blended into the landscape in the process of time.’

Typical examples of brownfield sites that may be contaminated

· Former factories

· Steelworks

· Petrol stations

· Landfills

· Mines

· Refineries

· Railways

· Military bases

A Land Contamination Assessment is carried out on behalf of regulators, funders, landowners and developers to identify whether there is, or likely to be contamination on a site where redevelopment may be proposed.

Importantly, the Land Contamination Assessment also identifies how the land could be made suitable for development following remediation work, therefore enabling the reclamation of derelict brownfield sites. A clear and pragmatic assessment is therefore vital.

For many Local Planning Authorities across the United Kingdom, this is a requirement of the planning process, to ensure redeveloped sites are safe for use.

There are four main stages involved in a land contamination assessment.

Stage 1 reports include a review of a desk-based information. This includes an assessment of the site history through research, and database searches, and the development of a conceptual site model, which identifies if land contamination is a concern. The presence of contamination does not necessarily mean that further action is necessary, where there is no linkage between the source and the receptor. A site walkover is also conducted to form this preliminary risk assessment.

Subject to the findings of a desk study, an intrusive investigation may then be required as part of the second stage of assessments. This enables on site soil, groundwater and gas/vapour sampling, as considered necessary by the initial desk-based research. Samples obtained are sent to a laboratory for analysis and results screened against acceptable threshold criteria for relevant contaminants.

The results of the intrusive investigations inform the appraisal of remedial measures required to ensure the site is suitable for the development for which it is proposed. Conversely, the intrusive investigation, and update of the site conceptual model, may reveal that remediation is not necessary.

Ultimately, this strategy avoids unnecessary costs, focusing on sustainable solutions for development.

Software and machinery have a strong contributing factor to the potential quality of the assessment also. Certainly, the right equipment should be used on each job, so therefore selecting a business that has the necessary means (with equipment) that can overcome the most common or uncommon difficulties on a project is important. This may include the type of land, terrain, access issues, or a simple case of the adverse weather conditions impeding the process.

Knowledge and experience of the individuals conducting the survey can also key. The Environmental Agency’s Land Contamination Risk Management (LCRM) guidance now places a larger emphasis on demonstrating the competence of those undertaking risk assessments and remediation. LCRM focuses on delivering sustainable benefits across the supply chain. Therefore, working with the right company will not only will give you peace of mind, but also potentially save you money in the long run of your project.

What happens if you discover contamination after starting construction?

If this occurs, you could be liable for remediation expenses to put it right. The organisation or person that caused the contamination on the site in the first instance technically would be responsible for these costs, however in a lot of cases, the contamination happened many years ago and trying to locate that person could be impossible. In this instance, the responsibility would be passed on to the new owner.

Jomas Associates undertake site investigations, land contamination risk assessments, geotechnical engineering surveys, flood risk assessments, amongst other surveys and are award-winning environmental and engineering specialists., working on construction sites across the UK. We pride ourselves on offering pragmatic, highly qualified, competitively priced, value engineering with pace. We’d be happy to talk to you about any future project you have and how it could be conducted to save you both time and money.

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