Background

As part of a £3 million Scottish Water investment to improve wastewater infrastructure in Paisley, works were undertaken to reduce the impact of combined sewer overflows on local watercourses.

The scheme at Buchlyvie Road formed part of a wider programme to improve screening performance, manage excessive flows during storm events, and enhance the water quality of local rivers and ultimately the River Clyde, delivering environmental benefits for aquatic life, flora and fauna.

The challenge

The project required the installation of a new combined sewer overflow (CSO), along with an APRNV chamber, new manholes and associated pipework.

Key challenges included:

  • Managing excessive storm flows without overloading the downstream sewer network
  • Meeting strict quality and performance standards set by Scottish Water
  • Installing a large below ground structure efficiently and safely
  • Achieving high construction quality within a constrained urban environment

A robust, precision engineered solution was required to ensure long term performance and programme certainty.

The solution

Following detailed discussions between Amey Black & Veatch, Keyline Builders Merchants and Marshalls, a bespoke precast flat pack CSO chamber was specified.

Marshalls designed and supplied a modular flat pack CSO, comprising eight individual precast components:

  • Four external wall units
  • A two piece split base
  • A central weir wall 
  • A single cover slab

The units were manufactured off site under controlled factory conditions and supplied via Keyline, Marshalls’ specialist distribution partner. Installation was carried out by specialist sub contractor Clean Tech.

The base slabs were installed at a formation level 3.24m below ground, followed by assembly of the walls and weir section. All joints were sealed using rubber seals and grout to ensure watertight integrity. The completed chamber measured 3.6m x 2.05m x 2.59m deep.

Compared with traditional in situ concrete or brick built CSOs, the modular precast solution offered improved quality control, faster installation and a safer construction process.

The outcome

The bespoke flat pack CSO chamber delivered measurable benefits for the project team and client.

  • High quality finish achieved through factory manufacture
  • Faster and safer installation compared to traditional construction methods
  • Improved programme certainty
  • Long term performance aligned with Scottish Water standards

John Townshend, Project Manager at Amey Black & Veatch, commented:

“The precast units offered a quality finish and the ease of installation assisted in delivering the CSO according to programme.”

He added:

“We now specify precast in preference to other options for structures such as CSOs.”
The project demonstrates the value of bespoke precast design in delivering efficient, high quality wastewater infrastructure upgrades.