Water & Wastewater Treatment

30 | MAY 2015 | WWT | www.wwtonline.co.uk In the know Skilling up: rope access the large pumps. Air is supplied to both sides of the sha via large plants located outside the sha with large vertical ductwork being used to distribute air evenly throughout the drywells. We have further innovated by the use of our original 'JETFLO' nozzles which are key to achieving a high ventilation efficiency by thoroughly mixing the air, diluting any heat and contaminants such as hydrogen sulphide and creating the best possible working environment. Air is extracted from low level from both sides of the sha, another key ATS design feature being that hydrogen sulphide is heavier than air and so collecting air at low level is another way we have increased the ventilation efficiency. Pumps are also located at low level and so we are able to capture heat at source and exhaust to outside. The Access Shas had different design requirements with a need to provide both general ventilation to the stairways, but also to pressurise the entire access shas for firefighting. The system has been fully designed in accordance with BS EN 12101-6:2005 to provide a Class B system for means of escape and firefighting. The design process has been challenging with lots of aspects to consider including selection of materials. The entire main sha ductwork system is 316 stainless steel in order to achieve a 20 year design life and with some of the ducts being 2.2m diameter we have used specialist construction techniques. Due to the depth of the pumping station replacement of ductwork will be very difficult and so selection of the correct materials is important. The entire access sha ductwork systems are 316 stainless steel, but fire rated for 4 hours. Installation The biggest challenge on this project was how we would safely complete the installation. Conventional methods such as scaffolding and man riders were considered, but it was impossible to use this method because of the space available and the need to access flanges and the like behind the ductwork. Installation via rope access was risk assessed as the most practical solution as it allows access to areas where scaffolding would traditionally be required, but would be inappropriate, prohibitively expensive or unsafe. Using rope access as a method of installation is innovative because it solves problems that traditional methods of access cannot. It was originally devised as a method of installation when ductwork was being fitted within a li sha and it became apparent that once scaffolding had been erected there would no longer be the space required to fit the actual ductwork itself. Scaffolding, the usual method of access, was simply impossible and would have caused programmed installation periods to dramatically increase, so it was clear that something more innovative was required. At about the same time as this, an A/C system was being fitted on the 9th floor, in a light-well of a building that had multiple owners/landlords. The time taken to receive the necessary permissions to erect scaffold would have meant costly delays to the project. Both of these challenges were overcome with a new innovative solution: the combination of IRATA rope access methods with the technical trade skills our operatives already had. Combining two existing skills is a major innovation in construction that has led to ATS being able to solve problems and provide solutions on both small and very large scales. About the Author: Rebecca Clissett is Operations Director at Air Technology Systems (ATS), design and project management specialists with over twenty five years of experience in providing effective, energy saving systems for industrial heating, ventilation, air conditioning, odour control and bespoke climate management solutions ATS's new rope access division has been able to install HVAC systems in hard-to-reach locations such as the Lee Tunnel (right)

• Cover