‘Toxic cocktail’: Department for Transport receives recommendations on highway runoff
Tyre particles, fuel spills and vehicle fluids pose a direct threat to the environment and public health.
A new report by Stormwater Shepherds and CIWEM has found that UK roads are a major source of land and water pollution, with rainfall and motor vehicle waste creating a ‘toxic cocktail’ of chemicals.
Rubber particles, heavy metals, and polyaromatic hydrocarbons [PAH] are among the biggest causes for concern in terms of ‘highway runoff’. Some are known carcinogens and have been proven to disrupt hormone balance in aquatic habitats.
It is believed hundred of thousands, if not millions of highway outfalls are discharging this potentially deadly concoction into water and rural environments. However, a lack of routine monitoring means the exact situation is difficult to ascertain, with the Environment Agency, National Highways and local authorities insufficiently resourced to perform this role effectively. This is despite National Highways having a statutory duty to control pollution from Britain’s road network.
Sampling from the River Lostock at Cuerden Valley Park, for example, showed PAH levels were above Environmental Quality Standards, with a further eight locations also showing concentrations were many times over the recommended maximum limit. Alarmingly, the sample with the highest levels of these harmful compounds were taken from an M6 outfall considered to be ‘low risk’ by the Highways England Water Risk Assessment Tool, used by National Highways to gauge the likelihood of pollution, calling into doubt the legitimacy of the measurement framework.
The report makes several recommendations to Government, including:
- The Department for Transport must look beyond other important issues such as road safety and be ambitious on wider issues that are of increasing importance to the public, such as managing the considerable environmental impact of roads.
- There must be far greater emphasis on the control of pollutants at their source, including enforcing legislation to control use of PAHs in the manufacture of tyres, and ensuring new Euro 7 Emissions Standards on tyre abrasion limits are properly adopted by manufactures when they come into force in 2025.
- All new road schemes should include good drainage design, and crucially provision for effective monitoring, operating and maintenance of drainage and treatment schemes.
- The HEWRAT model should be reviewed and its outputs compared with the risk assessments undertaken by the Environment Agency; we are concerned that there is currently no robust process to systematically prioritise the deployment of appropriate treatment for harmful runoff.
- A catchment-based approach to assessing risk of harm from highway outfalls should be adopted, so that the most polluting outfall sources can be prioritised for remedial action and the most cost-effective solutions developed.
- The introduction of extended producer responsibility levies on products such as tyres, fuel oils and brake pads should be introduced. This could provide the Department for Transport with greater budget to allow National Highways to install remediation schemes at high risk outfalls.
- Alternatively, or in addition, the introduction of a Stormwater Utility Levy should be considered (as used in Germany). Under this mechanism each household pays a monthly fee into a central or regional fund to pay for better management of surface water. This could be set up to give local authorities the power to prioritise and address polluting outfalls within their area, as well as delivering against wider government policy objectives, for example, storm overflows and surface water flooding.
- The Environment Agency should seriously consider issuing permits for high-risk outfalls from the road network. This would enable them to control the pollution by dictating the level of treatment that is required to protect the receiving watercourse and requiring that treatment devices be maintained and operated properly. It would also generate an income to allow the Agency to resource the control of the outfalls.
‘With political and media attention firmly fixed on sewage and, to a lesser extent agricultural pollution, the toxic and insidious problem of road runoff is driving largely unseen, under the radar,’ said Alastair Chisholm, Policy Director at CIWEM. ‘Highway pollution is often classified as ‘diffuse’. It’s anything but – it discharges in often highly concentrated ‘first flushes’ into small streams where the impact on ecology can be severe. And yet it’s not monitored and barely treated or regulated. This is yet another major nail in the coffin of our dying rivers which needs urgent attention.’
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Image: Neil Bates