Nags Head Lane STW – Brentwood

Project Management of a Humus tank Slip Ring and Slewing Bearing replacement was requested by Thames
Water at Nags Head Lane STW, Brentwood.

This included sourcing, supplying, and installing the assets requested using our confined space entry trained
mechanical engineers.


1) Thames Water drained the humus tank and then isolated it both mechanically and electrically.

2) Unitspark organised Industrial Water Jetting Systems to clean the Humus tank in preparation for the project.

3) Unitspark arranged scaffolding to enable confined space entry access into the Humus tank. Scaffolding was
also installed to enable access to the slip ring and slewing bearing.

4) The existing slip ring was electrically disconnected by an approved sub-contractor.

5) The unit was then mechanically removed. A new 20-way 400V slip ring was installed to allow suitable access
from the humus tank bridge in the future.

6) A new junction box was installed on the bridge to improve safe access along with a new rotary isolator.

7) Finally, a new slewing bearing was installed.

8) Commissioning was completed by dry running the bridge and false faults sent to ensure it operates as

9) Scaffolding removal.

Project Completed – 5 days