Near identical in scope, these two projects each involve the construction of four reinforced concrete chambers to house UV equipment that will treat final effluent prior to it being discharged into Southampton Water.

Millbrook was the first to get underway with Slowhill following on some four weeks later.

Each chamber measures 6m x 6m x 5m high, with about three meters buried below ground. To construct these safely, we have installed temporary works cofferdams. The frames were constructed by our directly employed workforce. The sheet piles, ranging in length from six to nine metres, were efficiently installed with a 35T excavator and Movax side gripping vibrating pile driver.

Once constructed to ground level, the structures are backfilled, allowing the removal of the cofferdam frames and sheet piles.

A further two meters of wall is then constructed to each of the four chambers to reach finished level.

Once complete they undergo water tightness tests prior to installation of the M&E (pumps, pipework, UV lights) by Galliford Try. Knights Brown will then install the large ductile (1200mm dia) iron pipework connecting the structures to the wastewater infrastructure.

Having the two projects running concurrently has enabled the sharing of ideas and lessons learnt, as well as the movement of our operatives and trades between the two sites as demand dictates.