Objectives
Costain were appointed by National Highways as the main contractor for the widening of the A12 from junctions 19 – 25 in Essex. The A12 has multiple gas mains (all pressure tiers) running parallel or crossing the A12. WFS were engaged by Cadent Gas to work with Costain to identify all the gas mains that have a conflict with the construction of the new A12. Through review of the Cadent Gas Network and the Costain proposals, Cadent Gas provided C3 design estimates to Costain.
Solutions
After reviewing the proposed road designs, the Project Designer from WFS provided proposed diversion drawings to the Cadent Design Engineer. WFS subsequently liaised directly with the Costain Project Managers to establish any areas where the proposed diversion would not work: the new proposed drainage; comms diversions; insufficient room within the proposed red line boundary. The Costain team engaged with the local communities and provided details on the planning applications and future developments that would impact on the Cadent design proposals prior to the start of the project. During this phase, the existing material of the low and medium pressure gas mains was reviewed, and updated designs proposed to suit the best connection points. WFS were also asked to review the NRSWA discount that had been requested by Costain to Cadent.
One of the biggest challenges WFS overcame was that the Development Consent Order (DCO) for the A12 scheme had not been submitted – Cadent were asked to confine their diversion designs to within the DCO. WFS had no prior information about the landowners that would be affected which resulted in the A12 design plans from the point of initial application to Cadent to the point of issue of the C3 costs, having to change several times. With each change to the design plans, the proposals had to be reviewed and updated where necessary. The area proposed for the DCO in 2 locations was reduced and WFS worked closely with Cadent to amend the proposed diversion designs to fit within the DCO.
Regular communications and meetings with other utilities and local Highways Authorities ensured best working practice and an agreed program of works.
Benefits
The Project Designer from WFS is currently working on another project for Cadent Gas so is able to keep a watching brief on the actions of all parties involved in theA12 project and will report back to Cadent directly if required.
