Stonbury reacted to the strict time limitations by mobilising five operative teams immediately, allowing many of the upstands to be completed before the winter months.
Under the scope of works, all upstands situated over or in contact with potable water were to receive a new waterproof membrane, using approved waterproofing systems. Excavation work varied across each site, however most tanks did require a complete dig out and removal before works could begin. The scheme required working with both gravel and soil topped sites.
Preparation work involved the removal of any existing defective coatings, followed by a high-pressure water jet to eradicate build-up of laitance and debris. Each upstand was then primed before a new waterproof membrane was applied, this would reseal the structure and safeguard against future water ingress.
Working to the required specification, Natcem fillets were installed to remove all 90° angles, avoiding any future damage from sharp edges. Over banding was also applied to seal the roof to the upstand joint offering additional protection against ingress.
A liquid membrane was applied to each upstand and finished with the application of UV Stable granules. On completion of each site, all gravel and soil were reinstated and finally handed back for sign off. Works were completed in good time and finished to an excellent standard, under ideal weather conditions.
In some cases, the scheme involved working over live tanks which demanded works to be completed under the highest levels of disinfection. A working enclosure was also required to protect the open access from the surrounding environment.
Whilst working over live tanks, our teams worked on each upstand one at a time, cleaning and disinfecting surrounding areas before opening the access hatches. Timber frames with sheeting were fitted around the upstand to prevent dirt, debris or foreign objects from entering the tank. Each hatch was safely lifted from the upstand, before being stored away from the opening.
Timber shuttering was constructed around the existing upstand, the new section was then cast using Natcem35 and left to cure. Once sufficiently cured, the shuttering was removed and all coating works were completed. Each hatch received a full disinfection prior to reinstatement.