Plean to Cowie Sewer Upgrade
Project Overview
We are upgrading the waste water network between the villages of Plean and Cowie in Stirlingshire to support new housing in the area.
The £10.3m project will see twin rising sewer mains installed along a 2.5 mile route from Plean Waste Water Treatment Works to Cowie.
Work began in late February 2025 and is expected to take 17months to complete.
At a Glance
- To support the development of new housing in the area
- £10.3m investment
- Delivered by Caledonia Water Alliance
- Work started late February 2025
Tunnel Challenge
The new sewer pipes are being laid underneath a motorway and a railway line
What We Are Doing
We are constructing new sewers from our Plean Waste Water Treatment Works to Cowie Waste Water Treatment Works in Stirlingshire.
The work involves drilling two new pipelines underneath the M9 motorway and railway line to the east of Plean.
Once completed, nearly 2.5miles of new sewer pipe will have been installed.
We have been working closely with other agencies including Transport Scotland, Network Rail, Forth Fisheries, Scottish Environmental Protection Agency and archaeologists.
No Delays
Tunnelling took place while traffic flowed as usual on the motorway above
Why We Are Doing It
New housing developments in Plean will see an increase in flows to our waste water treatment works.
The investment will support growth in the area and ensure the long-term service needs of customers are met.
24 hour drilling was carried out under the railway line
The two new rising sewer mains will cross 2.5miles of farmland
Update November 2025
We have completed a phase of 24-hour drilling work to install two 610mm diameter pipe sleeves underneath the railway to allow installation of the new sewer pipes.
