Experts are warning the UK should be braced for the risks of torrential rain and flooding this winter. The Met Office has said areas must be adapted to mitigate these risks created by adverse weather.
Flooding can pose serious problems for developments still under construction, creating hazardous conditions for workers or materials and causing delays to project timelines.
Construction teams can reduce the risks or likelihood of flood damage using sustainable urban drainage systems as preventative or protective measures.
What are sustainable urban drainage systems (SUDS)?
SUDS are designed into sites to prevent flooding by capturing water and controlling its discharge into nearby watercourses. They allow water to be held and discharged once the flood risk has reduced. As well as controlling the flow of water away from a site, they can also capture and divert silt, sediment or materials which would cause pollution.
Reducing the risk of flooding should be a year-round and whole-project approach, covering:
Before works begin:
- Assessing sites existing capacity – Understanding the land being worked on is essential to get precautionary, protective, or preventative measures right. This should establish what the groundwater level is and then assess how groundwater levels will fluctuate according to seasonal weather changes or from excavation or construction activities.
- Ensuring adequate drainage – Identifying where water naturally drains from and to, and how nearby watercourses can be reached, will ensure adequate, effective drainage. Sustainable urban drainage systems will then allow water to be captured, diverted, held and/or discharged at the right capacity.
- Understanding nearby resources or communities – Developers should know what properties, infrastructure and community resources, such as reservoirs or community flood defences, surround sites, to plan for and protect these.
During construction works:
- Monitoring water levels – All preventative measures should be regularly checked and maintained throughout works, and adjusted according to changing weather, including ensuring water is not building up in areas other than the designated sustainable urban drainage
- Ensuring accessible walkways and exits – Traffic routes, walkways and exits must remain accessible to move people, plant and materials should water levels begin to rise. Evacuation procedures must be in place and clearly communicated to all site staff and visitors.
- Protecting structures – Where ground that sits below or adjoins to a building or structure is liable to accumulate groundwater, subsoil drainage or dewatering treatments should be installed to ensure water cannot destabilise, impact or penetrate a structure.
- Installing detection devices – These will alert if water height reaches hazardous levels and can shut down machinery or water supply which could be affected.
After adverse weather events:
- Managing discharge of water – If water has overflown from drainage ditches or nearby watercourses, clearing or discharging this from site must be done carefully to avoid pollution elsewhere or negative environmental impact.
- Cleaning machinery or buildings – If flood water has reached plant or properties, these must be cleaned both to preserve their integrity and usage but also to ensure any silt or sediment in water does not reach watercourses, to prevent contamination.
While flood prevention measures nationally are overseen and delivered by the Environment Agency (EA), the Scottish Environment Protection Agency (SEPA) and local authorities, individual construction sites must follow the guidelines and understand which legislation or regulations apply to the area in which they are working.
What are the regulatory requirements?
Guidance on how to avoid or manage flooding is available from the EA, SEPA, and the Health & Safety Executive (HSE). Each focus on both preventative and corrective measures, to reduce risk and manage clean-up.
Guidance is given in line with the legal and regulatory requirements, including: the Water Environment (England and Wales) Regulations 2009, the Land Drainage Act 1991, and the Flood and Water Management Act 2010 (for England and Wales).
Flooding can be extremely hazardous so needs to be properly planned for, with protective measures carefully managed, to avoid interruptions to construction works, damage to buildings, or risk of pollution.
For more information or advice on how to manage and optimize construction sites, get in touch. Stratec are experts in geotechnical products and solutions.