Contaminated Land
When the Environment Protection Agency took to the problem of contaminated land and a new Environmental Protection Act was introduced, a more open policy of risk assessment was adopted, including the inspection of all sites and the publication of any contaminants found.
Chemical analyses for soil on brownfield sites usually reveal a large number of contaminants, but often the levels are low and we have been living with them (with unnoticed affects) for many years already. Due to this, specific levels of action are now in place for each contaminant, each based on their potential threat to our health.
While some chemicals present in the soil may not be directly harmful, they could be damaging to ecosystems or the groundwater and therefore affect us indirectly. Brownfield controls must therefore allow for a broad spectrum of situations.
Another factor to consider is the risk of methane migration, which varies greatly in different soils. In clay soil, methane may scarcely travel a metre or two, whereas in chalk or gravel it could migrate for up to 10 miles. Although the risk of someone being killed seems unlikely, the threat still remains and the potential to blight property from the merest suggestion of methane gas in the ground is a chilling thought. To date, there have been approximately 15 cases of methane gas explosions.
At significant levels, contaminants can not only affect our health, but can also cause damage to buildings by attacking concrete foundations. In addition to physical risks, there is also the matter of blight that can’t be ignored. Pollution is an emotive issue, and the talk of contamination can destroy property values, even when the actual presence of it is slight.
Should you purchase a brownfield site for sale, you should expect to see a condition of Planning Permission being a soil investigation survey carried out in advance of any building works. Apart from for the reasons already mentioned, any movement or excavation on the brownfield site can spread the contamination around.
The investigation will need to identify what contaminants are present in the soil, what the concentration levels of individual chemicals are, and whether they are inert or mobile. With mobile contaminants, some will have definite paths, such as radon gas or methane, which as a vapour will be heading to the surface. Other chemicals, such as leachates, can sink to pollute groundwater, so the report must also take these into consideration in order to deal with the contaminated land effectively.
Nick Maynard, Mercatus Land Consultants, April 2005
