Much Wenlock Flood Alleviation Scheme, UK

Shropshire Council has used NEC to reduce the flood risk to 171 houses in Much Wenlock near Telford. The project won the Environment Agency’s Project Excellence Award for Sustainability in 2018 and was highly commended for the Small Project of the Year Award in the 2018 British Construction Industry Awards.

The Council let a £2.1 million NEC3 Engineering and Construction Contact (ECC) Option B (priced contract with bill of quantities) to Welsh contractor Griffiths in October 2016. Designed and project managed by WSP, the scheme involved creating two upstream attenuation ponds − one on the Sytche Brook north west of the town and the other on Shylte Brook to the south west.

The ponds provide a combined temporary flood storage capacity of 18,000m³ during heavy rain, reducing flood risk from the town’s culverted watercourses to 3.33% annual exceedance probability. The ponds include retaining structures and Hydro Brakes to control outflows and are landscaped to provide new wetland habitats. In addition, most of the 41,000m³ of material excavated was re-used to convert a nearby disused quarry into a nature reserve.

The project was supported by the Environment Agency and funded through a Flood Defence Grant in Aid, Local Levy and the Council.  The contract was completed on programme and budget in July 2017.

Strong collaboration

Shropshire Council contracts manager Hugh Dannatt says NEC was used as it is the Environment Agency’s preferred suite of procurement contracts. ‘The scheme was fully designed prior to tender so we chose an ECC Option B lump-sum contract as the most appropriate form for engaging the contractor. The risk of carrying out the work at the prices agreed in the bill of quantities was borne by the contractor, but there was still a fair compensation mechanism for any changes in the scope.’

He says a key benefit of using NEC was the requirement for parties to work in a ‘spirit of mutual trust and co-operation’, which meant there was strong collaboration and teamwork throughout the contract.‘For example, while as much as possible of the excavated material was re-used in the pond areas, the contract required a total of 39,000m³ to be disposed at distant landfill sites. To reduce the social and environmental impact of the necessary 4,700 journeys by 20t trucks, the contractor and project manager suggested we buy a disused limestone quarry 2km from the Shylte site and restore it as a new nature reserve open to the public. It was a win-win solution for both parties’.

Dannatt adds that the NEC early warning process also ensured that all risks were identified and mitigated at the earliest opportunity, providing certainty on cost and programme throughout the contract. ‘For example, during the quarry works we unexpectedly had to stop work for 8 weeks to allow the local peregrine falcons to breed. We immediately held a risk mitigation meeting to plan how to to minimise the impact on the programme.’

Commenting after the Project Excellence Awards, Town Councillor David Turner said, ‘The flood alleviation scheme is the result of a number of partners working closely with the town council and the local community. This prestigious award is excellent news and recognises the unique local circumstances in this complex catchment, as well as the environmental benefits associated with the scheme.’

Benefits of using NEC

• NEC obligation to work in a ‘spirit of mutual trust and co-operation’ results in strong collaboration and teamwork between the parties, which helps to identify mutual beneficial opportunities for improving how the work is delivered.
• NEC early warning process ensures all potential risks to the programme and budget are identified and mitigated as early as possible, providing certainty on cost and programme throughout the contract.
• ECC Option B is ideally suited to projects where the detailed design is completed before tender, placing risk with the contractor but still ensuring changes to the scope are dealt with fairly and quickly.