Growing awareness that road runoff has an adverse effect on receiving waters.
Plus impact that roads can have on local hydrology and therefore on flood risk
Vegetated Drainage System for Road Runoff
Drainage Design For National Road Schemes – Sustainable Drainage Options
Management of contaminated runoff water: current practice and future research needs
The Pollution Potential of Road Salt on Freshwater Environments in Ireland
Guidelines on Procedures for Assessment and Treatment of Geology, Hydrology and Hydrogeology for National Road Schemes
Environmental Impact Assessment of National Road Schemes – A Practical Guide
Response from TII
TII does not routinely measure runoff from road projects.
The impacts of road runoff is quantified as part of the EIAR process and monitoring of drinking water wells is part of that process.
The details of the process are described in the following document:
This information is assessed by the local authorities and the commitments to carry the monitoring work are outlined in individual EIAR reports. TII do not collate this information.
The design of attenuation and conveyance systems on the national road network is established by TII road drainage standards. These standards outline the various options or drainage design to minimise and mitigate any water quality impacts – surface water and groundwaters. These standards are available on TII’s website.
Wetlands and attenuation ponds with reed beds are common across the road network as these systems offer the best treatment of road runoff.
TII is in the process of producing a new standard and technical guidance document for the assessment of water quality impacts. This is scheduled for completion 2023