The magnitude of toxic surface runoff

With climate change, increased rainfall and urbanisation in full force, the ‘unspoken’ pollution and toxicity of highway rainwater runoff is coming to surface. Toxic and poisonous pollutants such as PAHs (Polycyclic Aromatic Hydrocarbons) and metals which are emitted from vehicle exhaust, tires, brakes and more are very harmful to not only the environment, but also our health. With the increased rainwater, these toxins are polluting the rainwater surface runoff from roads and highways which inevitably enters the soil and the environment.

Until recently, toxic surface runoff caused by pollutants was mistakenly considered a natural occurrence as it is caused by rainfall. Essentially, this means that very little has been done to prevent and monitor toxic surface runoff from entering the environment and no action is being taken to reduce the pollution. However, in light of climate change, an attitude shift to greener behaviours and recent studies, the importance of addressing the toxic surface runoff is now considered paramount.

Recent research has found that some surface runoff water from highways is way above the legal limits for copper, zinc and lead and is entering the soil without any consideration. In 2018, there were 533 serious cases of toxic surface rainwater runoff reported, and this is only expected to rise with increased rainfall expected to come.

Hydrorock – the natural filter for surface runoff

As a highly innovative Aquifer SuDS system, Hydrorock is made from a natural process using 100% mineral Rockwool. This same wool has been evidenced by Wageningen Environmental Research as a highly effective material for filtering and dissolving these kind of toxins and pollutants from rainwater.

In a recent study, Rockwool was found to effectively retain 62% acenaphthene, 91% phenanthrene, 88% copper and 51% zinc molecules with its natural filtering abilities (Wageningen University & Research, 2020). Without this filtering, polluted surface runoff will continue to enter the soil, ultimately affecting the ecosystem and possibly ending up in our drinking water and food.

In a world where everyone is making conscious efforts to be green and reduce pollution, filtering surface rainwater runoff is the next natural step, and Hydrorock is the natural filter solution. Hydrorock can easily be used for retrofit projects, and when installed alongside roads and highways is most effective.

Hydrorock Water Infiltration

Hydrorock is made from a natural process using 100% mineral Rockwool

The economics

As well as this ability to filter and dissolve pollutants from toxic surface runoff, Hydrorock has a whole life assessment, meaning it is a sustainable and cost-effective solution that can absorb pollution for decades to come. After which, used Hydrorock can be returned to the UK Rockwool facility free of charge, where it is then recycled into Rockwool Insulation material. Hydrorock is a unique Aquifer SuDS which continues to be green beyond its lifetime; unlike other filtering systems which become hazardous waste once reaching their end of life and require expensive cleaning before being buried.

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