Specifications include, but are not limited to: Replace an aeration diffuser grid in the Wastewater Management Division’s (Wastewater) North Aeration Basin. The diffuser grid to be replaced is designated Grid A-2 of the North Aeration Basin. The diffuser grid assembly is a Sanitaire 9” diameter disc diffuser system incorporating 500 diffusers mounted on nine (9) diffuser legs emanating in both directions from a 12” distributor pipe spanning the basin width. The diffuser grid shall be fixed to the floor of the basin, in the same general location as the existing damaged diffuser grid, using only all stainless-steel fasteners and anchors, as supplied by Sanitaire. The contractor shall supply and install the new diffuser grid. Wastewater staff shall divert flow from the North Aeration Basin, drain the basin, and clean and remove any residual sludge to allow work in the basin. Prior to restoring the basin to service, the contractor shall also inspect all diffuser grid anchors and fasteners within the North Aeration Basin for corrosion, as evidence of the use of a carbon steel fastener or poor-quality stainless steel. Any corroded fasteners discovered shall be replaced by an equivalent stainless-steel fastener.
