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Accepted as a demonstration project under the Movement for Innovation in Construction initiative (M41), the Northern Ireland Department for Regional Development chose a design-build delivery approach for upgrading the Derg water treatment works.
Earth Tech was selected by the Northern Ireland Department for Regional Development to provide the design-build services. The project, executed under the IchemE Red Book Condition of Contract, involved replacement of an existing installation on an adjacent site, and upgrading the current throughput to 8.1 mgd (30.75 ML/d).
Good working relationships on site facilitated construction activity, which ensured the contractor achieved prompt approvals for design details and the client objective for a 24-month delivery contract was met without difficulty.
The process adopted included raw water intake and pumping, flash mixing for coagulation and pH control, parallel streams of flocculation and dissolved air flotation cells, removal of residual aluminum, granular activated carbon (GAC) filters for taste and odor control, manganese removal filters, twin treated water storage tanks each with 1.3 mgd (5,000 m 3) capacity, filtering dirty washwater collection and settlement, blending and thickening of DAF sludge and filter washwater sludge and chemical storage and dosing facilities.
A full computer-based control system was provided to enable the plant to operate unmanned outside normal working hours.
