Muswellbrook WTP Filter Refurbishment Works

Overview Muswellbrook Shire Council is seeking a contractor to undertake refurbishment works on the monomedia gravity filters at the Muswellbrook Water Treatment Plant (WTP). About The Muswellbrook WTP has ongoing issues with the plant's monomedia gravity filters, particularly with dead zones occurring during air scouring and backwashing. A recent inspection of the filters uncovered several nozzles completely blocked with filter media. Given the poor air scour and backwashing patterns observed, it is suspected that this issue is widespread across large areas of the filters. The filters originally used a monomedia (sand) configuration (mesh size 16-30 or 0.6 to 1.2 mm based on original filter specification) and a bed depth of 610 mm (excluding support media). The media was reportedly replaced in 2016. Specifications for the new media were not available, however it is believed to be similar to the originally installed media. The cleaning regime for the filters includes both backwash and air scouring (single rate air scour followed by single rate backwash). There is no combined air/water backwash as part of the backwashing sequence. Objectives The overall objectives of the filter remediation work are to restore the filter condition, with relatively minor upgrade works to improve performance and operation. Scope The scope includes: Cleaning and repairing the underdrain system in each filter Cleaning the filtered water flumes and filtered water pipework Replacing the filter media Constructing separate air scour grids Installing a screen on the backwash pump intake