The main project was undertaken as a joint venture design and build project by DAWSON-WAM in conjunction with Black & Veatch Contracting Ltd.
The DAWSON-WAM elements of the project were the design and construction of all civil and building works required for the provision of secondary treatment at the existing wastewater treatment works at Culmore, Co.Londonderry, with M&E Design and construction by Black & Veatch.
Civil engineering and building design works was sub-contracted to Hyder Consulting.
The works included:
The clearance of surface vegetation and trees from the whole area. All of the trees and shrubs were shredded and recycled to produce heat and power in a local bio-remediation unit.
Excavation and disposal on site in landscaped embankments of some 20,000 m3 of topsoil and mixed subsoils. Importing, spreading and compacting of some 9,500 m3 of stone fill in road and access area formation.
Construction in reinforced concrete of foundations, floor slab, bund walls and plinths for the new Sludge Dewatering Plant Building, which has a floor area of some 850 m2.
Construction of the Treatment Building superstructure, which consists of a structural steel portal framed structure with profiled steel cladding and roof, and brick faced concrete block outer walls.
The refurbishment of the existing Administration Building.
Construction in reinforced concrete of a large Activated Sludge Tank, overall dimensions some 78m x 66m x 4 m deep, 6 No. Final Settlement Tanks, 23m diameter, a 96m x 33 m x 4.5m deep Storm Retention Tank and 2 No. pumping stations, plus various other minor structures.
Construction of Air Blower and Odour Control Buildings.
The provision, excavation for and laying of some 6,500 metres of pipework, varying from 100mm to 1500mm dia. in various materials, together with associated manholes and valve chambers and surface drainage. In addition some 8,000m of 150mm dia. uPVC service ducts were laid between the various structures.
The construction of some 9,000 m2 of flexibly surfaced access roads, 500 m2 of concrete hard standing and 24,000 m2 of other access areas surfaced within gravel.
Ancillary works included provision of M&E services to the new buildings, site lighting, security fencing, landscaping and planting.
The designers of the reinforced concrete proposed the incorporation of granulated blast furnace slag in the mix design which resulted in an improved strength in the cured concrete and a resultant saving in the quantity of reinforcing steel required.
A total of some 12,000m3 of concrete and 1,300 tonnes of reinforcing steel were used in the project.
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