A waste stack in a 5 storey London hospital was repeatedly blocking and UKDN Waterflow were asked to investigate.
The first step was to create an access point on the roof to avoid disruption to hospital operations, and this was followed by aCCTV survey of this 100mm diameter stack. The survey revealed considerable diameter reduction caused by fat and hard scale.
Rather than use high pressure jetting, UKDN Waterflow used a mechanical boring device to restore full diameter without having to block off toilet connections etc. The only issue of concern was the noise of the device as it worked down the stack, and this was mitigated by speaking to the staff on each floor in advance, advising them on the probable noise level and ensuring they were happy for the works to proceed at the prescribed time.