LOCATION:
The second of two, £2m+ projects to complete civils works for the installation of UV equipment to treat final effluent prior to its discharge into Southampton Water.
The entire project was delivered by our directly employed in-house workforce.
- Surface water drainage diversions.
- Sheet piled cofferdams.
- Reinforced concrete structures.
- Transformer enclosure.
- Sundry bases and slabs.
- Duct runs and pits (up to 24 way).
- Ductile iron pipework up to 0.9m diameter.
Challenge
This project at Slowhill WWTW followed on four weeks after the start of work for a near identical project at Millbrook WWTW.
It required the construction of four reinforced concrete chambers measuring 6m x 6m x 5m high, with approximately three meters buried below ground.
Solution
To construct the four concrete chambers safely, we installed temporary works cofferdams. Sheet piles, ranging in length from six to nine metres, were installed with a 35T excavator and Movax side gripping vibrating pile driver.
Having been constructed to ground level, we then backfilled the structures allowing the removal of the cofferdam frames and sheet piles.
We then constructed a further two meters of wall to each of the four chambers to reach the finished level.
Once complete all the chambers underwent water tightness tests prior to the M&E elements (pumps, pipework, UV lights) being installed by Galliford Try.
We then installed the 0.9m diameter ductile iron pipework to connect the structures to the wastewater infrastructure.
Outcome
The two projects at Slowhill and Millbrook WWTW were the first to be delivered under ‘Project Shellfish’, a programme of work to upgrade water treatment quality and wastewater treatment capacity.
They were delivered for Galliford Try, Southern Water’s sole delivery partner for the western element of the AMP7 Framework Agreement.
The lessons learned at Millbrook were shared with the team at Slowhill leading to improved outcomes and more efficient delivery.
Resources and trades were shared and moved around to meet demand.
