February 2023: Updates to UK Radon Mapping
You may have heard that the official ‘radon maps’ for the UK have recently been updated, and the extent of radon-affected areas has increased. This means that some areas may now be classified as being at a higher radon risk than they were previously, and some may now require increased levels of radon protection.
The NHBC has released the following statement (full text available at nhbc.co.uk/builders/products-and-services/techzone/technical-updates/radon-protection-requirements):
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“All sites registered with NHBC from 1st December 2022 onwards will have been assessed against the updated radon maps by NHBC and will be required to have radon protection measures installed in accordance with the updated mapping. For sites registered prior to 1st December 2022, many customers have already taken proactive steps to ensure that those sites affected by the changes are updated to include any new measures required. From 1st February 2023 plots commencing construction will be required to have radon protection measures installed in accordance with the updated mapping to demonstrate compliance with NHBC Standards and Building Regulations. NHBC staff will be updating conditions to reflect this over the coming weeks. For those plots which have already commenced since the publication of the revised maps builders should discuss with their NHBC contact how best compliance could be demonstrated where a higher level of protection is required than has presently been provided.
NHBC will be contacting all builders affected by these changes and inspection and technical staff will assist builders with any related queries they may have.”
And representatives of the UK Health Security Agency (UKHSA) have said:
“While the vast majority of buildings remain outside radon Affected Areas, if the property you own is in a radon Affected Area, it is important that you arrange for a test. If you live in private or social rented accommodation, speak to your landlord, who should organise a test for you to carry out.”
We are waiting to hear further updates from the regulators / warranty providers on cut-off points for classification on previously built sites (if any).
It is strongly recommended that you should check for updates with your warranty providers and relevant local authorities on all schemes. It is also strongly recommended that all of your current sites / projects (and especially those which may have been assessed for radon risks prior to 2023) are compared by yourselves to the generalised radon mapping found at the following website (make sure the red button “Show Radon Data” is selected):
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ukradon.org/information/ukmaps
A ‘click’ on your site location should generate a pop-up box showing the radon risk. This is also colour-coded in each grid square, and the legend panel (bottom right) will also show the radon risk level shading when clicked. If the updated classification for your site area is shown to be higher than previously classified (i.e. whatever previous radon risk that may have been shown in ground search reports, solicitor / land agent search packs, geo-environmental reports etc.) then a higher level of radon precautions may need to be installed (subject to assessment).
Because the protection levels may have changed, we would recommend ordering a site-specific radon report from the BGS (e.g. shop.bgs.ac.uk/Shop/Product/GRS_S003, with other pages on the BGS site for Scotland) as this will confirm the risk levels at your site(s), and can sometimes show that the risk levels are actually lower than the general mapping can indicate.
We can arrange to have this checked for you, and can order site-specific BGS reports for your sites if required. Please get in touch if you require any help with this and we will confirm times / costs etc.
May 2023: New Guidance from NHBC for Housebuilders on Ground Gas
The NHBC have now released a guidance document for housebuilders which is presented as a document explaining and exploring "...good practice guidance on ground gas issues and housebuilding...".
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This guidance takes the reader through 6 stages of assessment, investigation, risk assessment and design / detailing / material specification and construction / verification. It also includes examples of standard details and example verification plans. The document references the EA's LCRM guidance at several points and recommends the input from experienced and competent professionals / engineers throughout, and the critical important of a thorough and robust desk study and accompanying conceptual site model is emphasised.
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We'd recommend that all clients should consider downloading / reading a copy, which is available at:
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​Hazardous Ground Gas - An essential guide for housebuilders | NHBC
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Sep. 2023: Surface Water Impacts from Ongoing Developments
Construction sites can create changes to the surface water that runs off them and into nearby watercourses. This could include silts, other suspended solids and contamination (such as hydrocarbons). This can happen during construction and even after development works are complete.
We have been increasingly asked to help our Clients with the sampling and analysis from brooks, streams and other watercourses near their developments over the past few years, and this seems to be something that regulators are keeping an ever-increasing focus upon.
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One of the most interesting trends we have noticed is that consistent data before and during such works can help developers to prove that their works are not impacting watercourses, which can be hard to prove without the right data.
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Oct. 2023: Drilling and Other Investigations at 'Tricky Access' Sites
Clients often need information on the ground in & around sites where access can be tricky. This can usually be related to access constraints, but some sites (and their users) are also sensitive to noise, disruption and other factors.
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Elemental GI Ltd have worked on many sites where 'clean drilling' and careful ground investigation works need to be completed so that the project team can get the valuable information they need on the ground beneath their feet. The collage below shows just a selection of some of these sites, where careful planning and discussions with the Client and site staff was essential before the works took place.
An unusual problem we have on some such sites is that we often leave the areas cleaner than we found them, presenting the site staff with extra cleaning duties after we've left so that the nearby ground is up to scratch!
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Jan. 2024: PFOS, PFOA and PFAS - The 'Forever Chemicals'
The compounds known as 'PFOS' (perfluorooctane sulfonate) and 'PFOA' (perfluorooctanoic acid) have been recognised as a risk to both the environment and to human health for many decades. These acronyms actually describe literally thousands of chemical compounds which are grouped together due to their similar chemistry and behaviour.
They are part of a group of compounds known as 'PFAS' compounds (per- and polyfluoroalkyl substances). These chemicals contain variable numbers of atoms including carbon, fluorine, sulphur, oxygen and hydrogen and were used for a variety of uses due to their resistance to water and oils / greases, making them highly stable in most environments. Whilst they were used for things like fabric / upholstery treatments and coatings for paper, they are perhaps most well known as an additive to fire-fighting foams.
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European rules prohibited the use of these compounds from June 2008, although they were already being phased-out prior to this as their environmental and health impacts become widely known. The most recent epidemiological studies make sober reading, and highlight PFAS compounds as factors in a variety of health effects including "... altered immune and thyroid function, liver disease, lipid and insulin dysregulation, kidney disease, adverse reproductive and developmental outcomes, and cancer." (Fenton et al. Environmental Toxicology and Chemistry (2021), 40(3), 606-630 ).
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In the UK the consideration of PFAS in contaminated land and groundwater assessments is critical, especially on sites with a history of the use, storage or disposal of these compounds. Fires should also be seen as a major risk of contamination from PFAS, as we found out following the Buncefield fire and subsequent environmental disaster which saw significant impacts to the groundwater.
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Feb. 2024: Caveat Emptor; When the Buyer Really Needs to Beware...
The step-by-step assessment and investigation of sites is common practice in the UK when Clients are looking at purchasing land, extending or simply undertaking a spot of due diligence. The ground beneath any site can hold a multitude of risks or none at all, and the only way to really find out for sure is to undertake a suitable investigation. Ideally this is done before any land is purchased so that the Client can adjust their offer, or even just walk away.
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Elemental GI Ltd are usually contacted at these very early stages by our Clients, and our assessments / surveys are typically the very first thing that happens on site (alongside things like topographical surveys or ecological surveys). However... sometimes we are invited to be involved at quite a late stage when the opportunity to identify and / or quantify a risk has already passed.
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We investigated a site in England in 2022 which required a coal mining investigation. The Client was made aware of this many years ago by another consultancy, but did not understand the risk or works involved. Elemental GI Ltd were appointed to undertake investigations half-way through the build programme, and unfortunately significant risks were identified on site. This sort of surprise caused huge delays, regulatory pressure and presented the Client with very large costs which were totally unforeseen.
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As part of our services we will help our Client to start the steps needed to remediate the issues identified and get their site back on track, but the early identification of these problems would have helped considerably.
March 2024: Wet, Wet, Wet...
The UK has seen a prolonged period of very wet weather over winter 2023/2024. It definitely isn't fun to work, walk, drive etc. in this weather, but it can also present various challenges to ground investigation activities and assessments...
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When rain falls on already saturated ground it can cause problems including pools / puddles of water (which hide the ground's surface), soft & slippery ground, and variations in soil, groundwater and ground gas conditions. From a GI perspective soft / wet ground can present real-life health and safety risks for both workers and their equipment. Some machines can sink, topple or become stuck quite easily, and whilst they can (usually) be rescued, damage to the ground surface is never pretty. There are also obvious risks and welfare concerns associated with moving around sites like this on foot, with trips and slips common.
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When the ground becomes saturated it also makes it hard(er) to log and assess it from an engineering viewpoint. Granular soils appear less strong, and cohesive soils can become softened quickly. Ground gas is also very hard to measure as monitoring wells become quickly flooded.
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April / May 2024: Still Wet...
The latest data from the Environment Agency shows that England has experienced the 'wettest' period for some time. Almost all areas have experienced more rainfall than usual, which continues to present issues for safe and efficient ground investigation work.
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But what else does this impact? Our Engineers have to think about these unusual conditions in relation to things like gas monitoring (flooded response zones), water sampling (unusually high turbidity / flow rates etc.), strength of natural granular soils and much more.
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The extract of a recent EA report is shown below:
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Water situation reports for England - GOV.UK (www.gov.uk)
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Feb. 2025: Pathogenic Bacteria in Soils
Soil is home to a vast array of microorganisms, including beneficial bacteria that promote plant growth, as well as harmful pathogens that can pose significant health risks to humans. Pathogenic bacteria in soil are a concern because they can cause a range of infections, particularly when humans come into contact with contaminated soil or consume contaminated crops. This is one of the many things that geo-environmental investigations will look for.
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Common soilborne pathogens include Salmonella, Escherichia coli (E. coli), Clostridium botulinum, and Campylobacter. These bacteria can enter the soil through contaminated water, manure, or organic matter, and they can survive in the soil for extended periods, especially under favourable conditions like moisture and warmth.
Humans are primarily exposed to these pathogens through direct contact with soil, inhalation of dust particles, or consumption of contaminated produce.
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For more information please see the latest guidance from UK regulators including LCRM at:
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