A sustainable, BBA accredited asphalt SuDS system that also contributes to BREEAM – Car park, Wigan

Chapel Lane Car Park, Wigan

Client

Wigan Council

Contractor

George Cox and Sons

Location type

Car park

Completion

August 2011

The challenge

To coincide with the opening of its new town centre offices, Wigan Council wanted to upgrade its busy car park at Chapel Lane. The existing car park was a combination of hard standing and made ground with no conventional surface water drainage. During periods of heavy rainfall, water would sit on top of the car park surface, making it difficult for car park users. The solution provided needed to overcome concerns of the local water company, United Utilities regarding discharge into the existing surface water drainage system as it was already operating at near to full capacity. The site was also previously used for gas storage and as a railway siding which meant that deep excavations also needed to be avoided to reduce the potential of interaction with residual contaminants.

Our solution

After looking at various options we designed an ULTISuDS system capable of storing 1 in 100 year rainfall event, discharging either via full infiltration into the sub-grade or combined with a restricted discharge. Our technical and construction teams worked with the main contractor’s site team to co-ordinate and assess the placement of the permeable geotextile, modified reservoir stone and the attenuation barriers. These were all installed in strict accordance with our drainage design, testing and quality assurance procedures, in order to protect the integrity of the warranty provided to the client to ensure the long term performance of the ULTISuDS system.

Results and benefits

The result of the project was to deliver cost savings of around £10,000 on an already competitively tendered scheme without affecting the integrity of the system. Close liaison in the design and installation ensured that despite the challenging situation, tight deadlines and restricted budgets, the scheme finished on time and under budget.

Additional info

Proven Performance

Using the latest porous asphalt technology and a modified binder, the open aggregate structure allows effective surface water runoff drainage and maintains long term durability on a wide range of SuDS applications.

Outstanding performance

ULTISuDS Achieves a Hydraulic Conductivity rating at installation of 5000mm/hr far exceeding the worst recorded UK rainfall of 100mm/hr.

Enhanced compliance

As part of a sustainable drainage system pavement, ULTISuDS meets the requirements of planning regulations and the Code for Sustainable Homes.

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