MOYGASHEL IMPROVEMENTS PROJECT
WDR & RT Taggart were engaged by Dawson WAM on this D&B scheme which included the construction of a new final effluent pumpaway for Dungannon WwTW. The work involved the laying of 8500m of 630mm HPPE pipe and associated pumping station, outfall works and flow monitoring plant, to convey treated effluent to the River Blackwater. The scheme also included the laying of 3750m of 125mm HPPE pipe for a smaller sewerage pumpaway laid along with the final effluent pipe over part of its route.
Dawson WAM completed the work generally by use of open cut trenching techniques, 95% of the pipe was laid in roads ranging from dual carriageway, hard shoulders to rural roads. The other 5% was laid in fields adjacent to the treatment works. Any section of the 125mmsewerage main not laid in the combined trench with the 630mm pipe where laid using directional drilling. This minimized the effect on the public of pipeline construction and significantly reduced the amount of traffic management and reinstatement required.
Two pumping stations were required to accommodate submersible pumps, measuring 3.6m dia. x 5.5m deep and 3.0m x 6.5m deep both of which were constructed using a 'top down' construction technique. The shaft was set up and sunk by excavating inside to lower the precast rings to the required level and once this was achieved the base slab was cast and the ring back grouted to seal any ingress of water.
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