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Ground investigation
Geotechnical consultancy
Contaminated land assessment

The contaminated land planning lottery

October 10, 2022
by Steve Branch

I have recently seen a couple of blog posts highlighting the different approaches that are required for contaminated land investigations to obtain planning consent in London boroughs. All well and good, and helpful for developers and other stakeholders to know some of the pitfalls, but I believe we are doing our clients a major disservice by blithely reporting and not challenging these requirements.

I have spoken to many other firms that have been working in London as long as or longer than we have, and they share the same frustrations when dealing with some of the London boroughs. And it is not always the individuals that are assessing the applications that cause the issues, as one London borough in particular clearly has a longstanding policy with regard to vapours that has been passed down through successive contaminated land officers.

Conversely, we are just commencing a project for a proposed basement in West London, and we advised the client that they might require vapour monitoring and groundwater sampling based on our recent previous experience in the borough. Before we started any work, the client applied for planning, and obtained conditional consent, with the following comment on ground contamination: No contaminated land condition is recommended for this planning application as the chance of significant contamination being found with the potential to cause harm is considered to be low. This is good news for the client, and a completely reasonable response from the planners, given that the site is in a longstanding residential area that has had many similar developments over the past 20 years. But it is a very unusual response, especially as there has not even been a desk study carried out, and makes life very difficult for those of us that are advising prospective developers on the extent of investigation required. It is this inconsistency within boroughs – sometimes within the same street – as well as the inconsistencies between boroughs that are causing problems. And it really doesn't seem to be that difficult to solve some of these issues through some discussion between interested parties.

It is quite informative to compare the approach to contaminated land assessments to what's required in the assessment of planning applications for basements. So, for example, in London Borough of Camden – often seen as the trailblazer for this sort of assessment – a report was commissioned from Arup on the issues relating to basement development, and from their subsequent excellent report, published in 2010, the council developed planning guidance that is clear and straightforward. Some of the guidance might appear a little onerous, but we all understand what's required. The technical content of a basement planning application is audited by a third party engineer – currently Campbell Reith – and they provide an audit report highlighting any concerns or point that they consider need to be addressed. Assuming that a competent firm is working on the project these points are generally easily resolved and in rare cases where we don't agree with their conclusions they are happy to arrange a meeting to discuss resolutions. In short, the system works well for all concerned.

Compare this approach to a West London borough's approach to soil vapours. For reasons of their own, this borough is more concerned about vapours than any other, apparently due to historical problems. So, a nearby historical usage found in the desk study that in another borough would not be of concern, will in this borough lead to a requirement for extensive monitoring, including internal ambient air monitoring, and often installation of gas and vapour protection measures. We have probably carried out vapour monitoring on over 50 occasions in this borough and have never found any vapours at concentrations that would be of concern in any other borough. Other firms are doing the same, and we all do it rather than object, as the primary objective for the client is to obtain planning and the cost of the monitoring and vapour protection is less significant than the cost of delays.

Apart from the cost of additional monitoring installations, monitoring, and delays, and the cost of unnecessary protection measures, the carbon cost over the years must be substantial – each monitoring programme requires six journeys into London for example – and there is the extra carbon associated with the gas protection materials and associated additional construction cost.

It cannot be logical that we need to address concerns in this borough that aren't required elsewhere and the approach to planning applications in this borough doesn't make sense – why is soil vapour a problem in this borough and not others? Why are technical arguments that we provide to this borough disregarded out of hand, but they are accepted elsewhere? The answer always seems to be that there have been problems in the past with vapours, so every site should be treated with more caution than in elsewhere. But this seems to me to be completely the wrong approach and what should be happening is that the source of vapours on the sites that resulted in the borough having this attitude should be investigated. If something unusual was found then let's find out why, rather than assuming that every other site could be similarly affected. We would be delighted to have input into a study into historical problems and I am sure there would be environmental consultants lining up to take part. There is now also a huge database of vapour monitoring in the borough that isn't being used, so let's use that data to allow a strategy to be formulated for the assessment of planning applications. Some simple rules and guidance would make submission and assessment of applications easier and quicker for all parties.

For the sake of our clients developing sites in London, we need to find a different way of working with these particular London boroughs, as there is obviously no sense in simply accepting that in one or two boroughs the work required to discharge contaminated land planning conditions is going to cost two or three times as much as elsewhere, and take months (or sometimes years) rather than weeks.

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