Works were recently completed at two separate Water Treatment Works to increase the aggregate storage capacities. In total, six new standalone bays were constructed and a further two existing bays extended for increased capacity, used to store dirty sand, clean shingle, dirty shingle and carbon.

The new standalone bays were constructed in grassed areas on the two sites, works involved excavating the area approximately 600mm deep and the excavated spoil was removed from site. Type 1 fill was imported and placed in the excavation and compacted. A foundation was cast around the outside of the bays, which was then concreted, followed by the installation of precast concrete wall units. Some bays used 2.5m high wall units and the remainder used 3.2m high as per the specification.

Reinforcing steel was layered onto the compacted type 1 fill and then C40 concrete was brought to site in ready mixed lorries and pumped into the bays, forming a 200mm thick concrete slab.

Some challenges were uncovered during the construction process. Existing underground services were found, which were previously unknown to the client, resulting in reconfiguration of some of the bays.

The project also encountered some planning changes along the way, resulting in some of the bays to be extended from the original scope and allowing greater storage capacity.

Planning and timing schedules were adapted accordingly to accommodate these changes, completion of the projects were still completed for our original deadline.

Drainage has also been installed from the bays, connecting at a nearby main drain. Sand traps were installed using precast concrete rings and a bespoke mesh cover, with hinged access hatches. These were fitted to the top of the sand trap, providing access for the client to empty as required.

In addition, the existing wheel wash on both water treatment works had to be modified and a new Karcher industrial pressure washer was installed on both of these sites, housing a new steel enclosure.

The wheel wash at one of the sites had been condemned because of a bacteriological failure, due to the water being re-circulated. We changed the configuration of this wheel wash and connected the waste water into the main site drainage, so only clean water was circulated each time the wheel wash was used.

We have been asked to carry out extra work on one of the two sites, to strengthen some existing media bay walls. The work will involve excavating in 3 locations on each wall, installing a 150mm x 150mm x 3.5m long RSJ down the back of the wall and casting a concrete block around the RSJ, followed by securing the RSJs to the existing wall, before finally painting yellow and black hatching to improve visibility for site traffic.