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Horley Waste Water Treatment Works (WwTW)

Sector

Waste Water

Product(s)

Rotating Scraper System

Contractor

Eight2O

Contract Length

4 months

OVERVIEW

Background

JK Fabrications Ltd was engaged by the Eight2O Alliance to undertake the replacement and refurbishment of Rotanox Tank No. 5, which had reached the end of its operational life.The works formed part of Thames Water’s wider infrastructure upgrade programme to ensure the long-term efficiency and reliability of its wastewater treatment assets.

The project required the complete decommissioning, dismantling, and reconstruction of the existing Rotanox tank system, including both the inner Final Settlement Tank (FST) and the outer oxidation ditch.

Scope of Works

JK Fabrications’ turnkey scope covered all mechanical design, fabrication, supply, and installation elements associated with the refurbishment, including:

Drain down and clean-out of the existing Rotanox Tank No. 5, including handling, pumping, and removal of residual sludge in accordance with site procedures
Dismantling and removal of the existing inner and outer tank walls and the obsolete FBDA system

Design, manufacture, and installation of new Glass Fused Steel (GFS) tanks:

Inner FST tank: 15.5 m diameter × 3.6 m high
Outer oxidation tank: 28.9 m diameter × 4.78 m high

Replacement of the FST scraper bridge, including:

Main bridge structure, tripod, slewing ring, scraper system, and scum skimmer
Drive motor, gearbox, slip ring collector, handrail system, and new cablin
Flooring clips compliant with Thames Water asset standard
Replacement of the outlet launder system with new stainless steel weirs and scum board
Installation of new FBDA aeration system
Hydrostatic testing of both tanks to verify structural integrity and watertightness

Outcome

JK Fabrications successfully completed the replacement of Rotanox Tank No. 5, delivering a modernised, high-performance glass-fused steel tank system fully equipped with new mechanical and aeration components.

Following installation, the tanks and scraper system underwent comprehensive hydrostatic and functional testing, confirming full compliance with Thames Water and WIMES specifications.

The upgraded system has since provided enhanced process reliability, ease of maintenance, and extended service life, supporting the continued performance of the treatment works.

This project highlights JK Fabrications Ltd’s capability to manage complex refurbishment works within operational treatment environments — delivering safe, high-quality solutions that align with Thames Water’s engineering standards.