When constructing a new car park, a stormwater management system should always be considered to prevent localised flooding. As one of the UK’s leading stormwater specialists, we are experts in this field.
Here is a recent example of a stormwater attenuation system we supplied and installed for construction company Henry Williams and Son (Roads) Ltd, when they built a new car parking facility at a North West NHS hospital.
The Stormwater Management Challenge
The North West-based NHS hospital needed to extend its car parking facilities after patients, staff and visitors were struggling to find parking during peak times. They purchased nearby land to create an additional 338 parking bays to manage overflow traffic.
With the new car park came concerns over potential flooding. The impermeable surface would significantly increase surface water runoff, placing added pressure on local sewers during heavy rainfall.
A sustainable surface water management system was therefore identified as a key requirement for the 7,000 m² car park. Henry Williams and Son (Roads) Ltd — the construction contractor for the project — contacted the team at Cotterill Civils.
The Solution
We supplied and installed a stormwater attenuation system to ensure the car park met Defra’s Sustainable Drainage Systems (SuDS) regulations. SuDS provides a natural and sustainable approach to managing surface water around developments.
The system was built using stormwater attenuation crates, which offer an economical and versatile solution to stormwater management. The crates were lowered into an excavated area and interconnected to create one large below-ground holding tank measuring 355.2 m³ (12 m × 37 m × 0.8 m).
To prevent water discharge into the substrate and block soil or sand particles, the crates were wrapped in a geotextile protective fleece and an impermeable membrane with heat-welded joints.
The below-ground tank fills during heavy rainfall, holding excess stormwater which is then slowly released back into the main sewer via a hydrobrake, preventing localised flooding.
Sean Martin, MD of Henry Williams and Son (Roads) Ltd, commented:
“We were really pleased with the stormwater attenuation tank installation Cotterill Civils did for us. Despite the tight timescales, they completed the works one day ahead of schedule. The off-site support was excellent, and the on-site team showed high standards of health, safety and quality throughout. We would definitely use Cotterill Civils again.”
If you’d like more information on our stormwater attenuation solutions and installation service, please call us on 0121 351 3230.
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