KEY FACTS

CLIENT

Stoford Properties Limited

BUILD TYPE

New Build

SERVICES PROVIDED

Geotechnical Engineering
Earthworks
Civil Engineering
Structural Engineering
Environmental Reporting
Flood Alleviation and Mitigation Design
Transport Planning

PROJECT DESCRIPTION

BWB is proud to have played a key role throughout the planning and implementation stages of this 70-acre office and industrial space development at Junction 6 of the M5.

Stoford Developments initially commissioned BWB to provide transport, infrastructure and environmental consultancy services to secure commercially viable planning permission. Following the grant of planning consent, we have undertaken the detailed design of the enabling infrastructure and the initial phases of plot development works, including the civil and structural engineering design of all buildings constructed to date.

When complete, Worcester Six will provide over 2 million sq ft of employment floor space in a unique business environment, with over 850,000 sq ft having already been delivered or committed across the scheme.

Our key achievements on the project include:
- Value engineering to reduce the cost of a publicly funded highway scheme in order to facilitate development
- Obtaining approval for a commercially viable yet ecologically sympathetic watercourse diversion/drainage strategy
- Establishing a balanced earthworks strategy that permitted phased development and reduced movement of material
- Negotiating with the Highways Agency to facilitate the initial 700,000 sq. ft. of development without any need for off-site highway capacity improvements
- Negotiating a significantly less onerous Travel Plan than previously required, including considerably less exposure to funding improved bus services.

Key Challenges

BWB designed works to enable two 7m by 3.5m launch pits and two 4m by 3.5m reception pits excavated to depths of approximately 4m below original ground level. The launch and reception pits were located to the east and west of the motorway respectively at a distance approximately 15m away from the motorway edge.

Two 1200mm internal diameter and 1430mm external diameter pipes were installed in a 1450mm diameter bore created via the pipejacking technique. The linear distance covered by jacking pipes is of the order of 80m.

For monitoring purposes, a number of survey points were marked by the Main Contractor (McPhillips) between the edges of the launch and reception pits and the toe of the motorway embankment. Allowable settlements in relation to the works was agreed between BWB and necessary project stakeholders.






The major challenge for this scheme was to avoid excesses settlement of the live carriageway of the M5 motorway; a worst case scenario would be based on the full collapse of the overlying material and as such could equate to potential collapse of the existing carriageway level by up to 1.45m (based on maximum diameter of pipe jack equipment). However, utilising the pipe jack solution, the tunnel is created behind the digger shield as the excavation is taking place within the shield. This method results in a flexible, structural, watertight tunnel as material is excavated, which therefore generally reduces the amount of overbreak that can occur from other techniques. Additionally, as the pipe jack is advanced the final pipes are placed as the excavation occurs and therefore it is considered to provide better ground support as there is no downtime between completing the excavation works and the installation of the pipes. This equally reduces any potential issues of heave at the base of the excavation.

For monitoring purposes, a number of survey points were marked by the Contractor between the edges of the launch and reception pits and the toe of the motorway embankment. Monitoring was continued during works as well as for a duration of 10 weeks following completion in order to capture any post completion settlement. Based on monitoring data no excessive settlement was recorded.

BWB managed the geotechnical certification process effectively and ensured timely project completion. Efficient design and supervision of the works including adoption of trenchless technology proved to be both cost and time savings for the Client. It was ensured that there were not disruptions of the live infrastructure of the M5 motorway.

Following this project the HE recommended BWB to service providers on other schemes.

KEY CONTACTS