Scottish Water has started the procurement process for a contractor to design and build its proposed £100m 5km long sewer tunnel in Glasgow.

The utility is currently considering two designs:

• a shallow tunnel crossing major infrastructure road and rail routes
• a deeper tunnel within stable bedrock that would need a lift pump station

Depending on the final choice, the 4.5m diameter tunnel will be driven at depths of between 10m to 30m. It will also run across an area of old mine workings - raising potential technical problems.

The tunnel will also have to be connected to the existing sewer network at both ends.

Deadline for expressions of interest for the project, which will run for an estimated seven years from contract award to finish, is 10 December Submission must be made via e-mail to This e-mail address is being protected from spambots. You need JavaScript enabled to view it