LOCATION:
The first of two, £2m+ projects for civils works to enable 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 1.2m diameter.
Challenge
This was the first of two, near identical projects with the second at Slowhill WWTW getting underway four weeks later.
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 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 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 1.2m 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.
With the second site at Slowhill following on a few weeks later, we were able to share knowledge gained between the two sites leading to improved outcomes and more efficient delivery. We were also able to share resources and move operatives and trades between the sites as demand dictated.
