Sweet Smell of Success for Gee & Company in Isle of Man
Working on behalf of their client - leading chemicals supplier YARA - Gee has recently supplied a series of chemical dosing systems, including two Michael Smith design KTB packaged plant systems, for septicity control at four sewage pumping station (SPS) sites across the Isle of Man.
This rise in demand for water causes odour control challenges: In autumn and winter, the retention in the rising main increases, causing septicity. During colder weather this tends not to be such as problem as the bacteria which cause this are less active. From spring onwards however, the smell increases as bacterial activity in the sewer main increases – emanating not only from the pumping stations themselves but also from the breather points on the line.
During the spring and summer months the sewage temperature increases and the average flows of sewage through the sewage pumping stations decreases. This results in the sewage experiencing longer retention times within the sewerage network and increased biological activity due to the increased temperatures. This causes high levels of septicity within the rising mains and wetwells, resulting in odours at the sewage pumping stations and vent stacks within the catchment.
Another problem associated with septic sewage is the fact that the nuisance smell, namely hydrogen sulphide (H2S), combines with oxygen to form sulphuric acid (H2SO4) which is naturally highly corrosive to the metallic and concrete infastructure.
The contract was challenging in terms of both the dosing algorithms for odour control and most importantly the engineering required from Gee. Yara won the contract to use their Scinox™ product thanks to their in-depth understanding of the role of nitrates in the control of odour and corrosion within the sewerage network and application of their multi-node model. Scinox™ comprises a special blend of environmentally friendly nitrates and when combined with an “intelligent” dosing and monitoring system such as those designed and supplied by Gee, ensures a healthy environment and prevents odour nuisance.
From the chemical dosing perspective, the demands at each site varied enormously, requiring Gee’s engineers to be at their most creative and versatile. At the Athol Park site in Port Erin, and at the site on Loch Promenade in Douglas, space and working height were at a premium.
For the Loch Promenade site Gee’s engineers developed a solution comprising a dosing skid fitted with their Signal Series 300 API 675 rated dosing pumps, plus two five cubic metre chemical storage tanks – all ATEX rated and sited within a zoned area – which they manufactured and shipped to Douglas in parts and then re-assembled underground in situ.
A similar approach was taken at Athol Park where there was space for only one 15 cubic metre storage tank which again, had to form part of an ATEX rated, zoned system.
Elsewhere on the island, at the Ballanorris and Ronaldsway pumping stations, Gee utilised their innovative Michael Smith design KTB packaged plant systems fitted with Signal Series 200-EMP3 dosing pumps with 100:1 turn down ratio for precise control.
The KTB packaged plant units utilised in the Isle of Man were manufactured and fully hydraulically and electrically tested in Birmingham prior to despatch. They were delivered to site on low loaders, and the off-loading, positioning and installation were all managed by Gee’s trained engineers who supervised all the final connections leaving the plant “ready to run.”
The KTB’s versatility, compact design and low height plus the fact that there is no walk-in access, greatly assists in smoothing the planning process and this combines with shorter design/installation times to significantly reduce the overall project costs.