Environment-Flood Risk
TarmacDry delivers a number of important environmental benefits such as:
- Improves the quality and purity of stormwater run-off through natural water treatment
- Helps to re-charge ground water levels
- Reduces traffic noise compared to standard asphalt and block pavoirs
- TarmacDry's porous properties improves road safety through reducing spray and the risk of aqua planning on standing water
- Optimisation of land-take
- Facilitation of rainwater re-use
TarmacDry pervious pavements limit the concentration of pollutants by immediate localised interception and long term research conducted by Coventry University has demonstrated that the following pollutants are effectively removed from stormwater run-off:
- Heavy metals
- Hydrocarbons
- Phosphorus
- Nitrogen
TarmacDry porous pavement systems can minimise the need for costly traditional petrol / oil interceptors and can be used as a primary treatment facility in accordance with best practice guidance eg CIRIA C697 'The SuDS Manual' usually without the need for further treatment.
Trials at Coventry University
Ongoing trials at Coventry University are demonstrating that
within a TarmacDry porous asphalt and in-situ
porous concrete system, microbes develop naturally in response to
ongoing contamination. The microbes are able to treat and trap the
contaminants and this capability is further enhanced by filtration
and aeration within the construction.
The main conclusions from the testing undertaken at
Coventry University are summarised below:
- Water containing street dust was applied in measured amounts onto the surface of a number of different test rigs each having different layer types and thicknesses, the aim being to capture the outflow water at the base of each pavement structure and measure pollutant levels.
- The heavy metals present in the outflow samples are at concentrations below the WHO drinking water specifications.
- Suspended sediment concentrations are all mainly below background levels suggesting that it is being trapped within the test rigs.
- Used engine oil was applied every 4 weeks as a single dose to each test rig at a rate of 25 ml/m2 until the effluent oil concentration reached 10mg/l. All of the concentrations measured in the outflows from each test rig were very low (below 1 mg/l) .
To date results from the Tarmac study at Coventry University indicate that the pollutants which have been applied to the rig surfaces are being held in the structure of the pavement. There is no evidence to indicate that any of the applied contaminants will reach breakthrough point.
See more on Flood risk elimination using SuDs
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