Water and Effluent Treatment Magazine
Issue link: https://read.utilityweek.co.uk/i/411335
4 WET NEWS NOVEMBER 2014 The elevated works occupy a compact footprint, fed by 5-off large screw pumps. Any failure in the fundamental design could have caused extensive damage to the surrounding area Close encounters of the collaboration • A £1.2M project at Belfast WwTW included the of supply of equip- ment, mechanical in- stallation and commis- sioning at the inlet works. TECHKNOW • The scope of supply covered six EscaMax Screens (5,000 x 2,252 with 6mm perforated plate); six RakeMax Screens (4,300 x 2,250 with 50mm bar spacing); four WAP-SL BG12; all launder channels; and DN350 knifegate valves • Equipment supplied comprised EscaMax Screen throughput 2,100 l/s peak flow per screen (5-off duty screens and 1 standby); RakeMax Screen throughput 2,100l/s peak flow per screen (5-off duty screens and one standby); WAP SL max throughput of 15m 3 / hour per unit (Duty / Standby – Coarse Screens and Duty / Standby Fine Screens); Launder Channels for a flow rate of 25l/s. • Phased installation essential, and the equipment had to also fit within the existing very tight sites hydraulic constraints NEED TO KNOW 1 The existing 6-off coarse and 6-off fine screens on site continually caused issues with carry-over of screenings, leading to reliability problems and requiring high maintenance 2 Any failure in the fundamental design could have caused extensive damage to the surrounding area 3 The well-known five Ps acronym – proper planning prevents poor performance – was particularly relevant in this case T he successful delivery of any wastewater project, large or small, does not just happen. It typically involves people from many different dis- ciplines and who are highly ex- perienced and, very important- ly, have good local site knowledge. The upgrade of Duncrue Street, Belfast, was an example of the considerable col- laborative effort needed from the outset to ensure a successful outcome that exceeded all par- ties' specifications and site re- quirements. From the initial enquiry around three years ago, regular dialogue took place between NI Water, the design consultant, contractor and Huber. Gerard McKeever, project manager for Graham Construc- tion, comments: "In January 2013 Huber Technology were appointed as a sub-contractor to Graham Construction to supply and install six new course and fine screens at Belfast WwTW under the IWWF Phase 2 Base Maintenance scheme. Works commenced on site in July 2013 and were successfully handed over to NI Water in May 2014." A thorough understanding of the hydraulic conditions of the site were of the utmost impor- tance. The elevated works, which occupy a compact foot- print, fed by 5-off large screw pumps presented its challenges, and any failure in the funda- mental design could have caused extensive damage to the surrounding area. Flow and rags The existing 6-off coarse and 6-off fine screens on site, along with their associated dedicated (very long) screw conveyors and handling equipment, were con- tinually causing issues with carry-over of screenings, lead- ing to reliability problems and PROJECT SPECS • Install six new course and fine screens at Belfast WwTW, under the IWWF Phase 2 Base Maintenance scheme • Consider the very specific site hydraulics and control philosophy requirements for the site, along with the right selection of equipment and its associated sizing • Eliminate the need for the very complicated and maintenance intensive screw conveyors and duty / standby change over systems THE VERDICT "The reliability of the Huber equipment has been excellent giving just minor teething problems which have been addressed and sorted effectively by both Huber and main contractor Graham Construction. "The screening capture rate, by both the coarse and fine sets of screens is excellent, evident now by how quickly the skips fill, and the significant reduction in sewage-related debris downstream of the screens. This has meant less pumping and treatment process problems for myself and break downs for NI Water M&E" Peter Neeson, operations manager from NI Water ONSITE WASTEWATER TREATMENT requiring high maintenance. This compounded with the high peaks of loadings in respect of flow and rags meant that the operation of the works involved large amount of manpower and monitoring to take place. Huber was tasked to take into account the very specific site hydraulics and control phi- losophy requirements for this site, along with the right selec- tion of equipment and its asso- ciated sizing. The coarse screens chosen were used to protect and reduce the solids loading onto the 6mm escalator screens, which have one of the highest screenings capture ratios on the market today of 84%. This would ensure that pump block- ages and rags were not carried over into the works. Additionally, Huber sug- gested that a launder system be utilised to eliminate the need for the very complicated and main- tenance intensive screw convey- ors and duty / standby change over systems. As with all projects of this scale, good communication was essential, and regular projects meetings at all stages of the con- tract, ensured that all parties were informed and agreements about the most important deci- sion were made collectively. The well-known five Ps acronym – proper planning prevents poor performance – was particularly relevant in this case. Huber supplied six EscaMax Screens (5,000 x 2,252 with 6mm perforated plate); six RakeMax Screens (4,300 x 2,250 with 50mm bar spacing); four WAP- SL BG12; all launder channels; and DN350 knifegate valves. Equipment supplied comprised EscaMax Screen throughput 2,100 l/s peak flow per screen (5-off duty screens and 1 standby); RakeMax Screen throughput Close encounters of the collaboration Your