Specifications include, but are not limited to: The Work under this Contract includes replacement of the trickling filter rotary distributor mechanisms and high pressure air lines for four trickling filters, replacement of the adjustable slide gates within the trickling filter tower, removal of side mounted ladders and replacement with aluminum stairs (additive alternate item), and all appurtenances. The Work for this Project will occur at the WLWPCF. This facility continually treats wastewater from the Salem/Keizer area and operates 24 hours per day, seven days a week. The successful Bidder for this Work will be required to follow very strict work and shut-down sequences in order to prevent any interference with on-going Plant operations