Removal of filter media: Contractor shall remove all filtration media from Filter #1 Basin. Contractor shall carefully collect the top layer (approximately 24 inches) of anthracite filter media and place it in 2,000 pound capacity polypropylene bulk bags (Super Sacks). The bulk bags shall then be stored in an area of the treatment facility designated by plant operating staff. The remaining material - silica sand, garnet sand, and garnet gravel, shall be disposed of in owner provided roll-off dumpsters. Underdrain Cleaning: Contractor shall unfasten and remove all stainless steel underdrains from filter basin being careful to retain all fastening materials for later reuse. Following removal, cleanly remove the end cap of each underdrain to facilitate a complete cleaning of the underdrain tube interior. Removal of the end cap may require cutting the stainless steel endcap off in a manner that will allow for reattachment after cleaning of the underdrain. Completely clean and rinse all filter media and debris contained within the interior of the underdrain tubes. Contractor shall reattach end caps following underdrain cleaning. Only stainless steel filler rod will be permitted for the reattachment of the endcap if removed by cutting. TIG welding using 100 % Argon shielding gas will be the only approved method for reattachment of endcaps. Contractor shall ensure no openings or gaps remain after reattaching end caps. Reset underdrain: Prior to resetting underdrains, Contractor shall coordinate with plant operators to flush the underdrain piping into the filter basin to remove any media or debris located within the piping. Contractor shall remove debris, if any, deposited in the filter basin following the flushing. Note: Any draining of the filter will require the use of a sump pump. Contractor shall replace all underdrain gaskets prior to setting underdrains. Gaskets may be purchased from the manufacturer. Item number 247223, 4 inch diameter, quantity - 20. Manufacturer recommends using an NSF approved lubricant on the inside of the gaskets and the drop pipe to avoid any damage to the gaskets. Contractor shall reuse existing fasteners to reattach screen to filter basin floor. Any floor anchors discovered in poor condition, damaged, or loose may be replaced using type 316 stainless steel concrete anchors and approved concrete epoxy. Underdrain shall be mounted to floor in a manner consistent with manufacturer recommendation to avoid damaging or deforming underdrain openings. Underdrain system presently in use is a Triton Underdrain as manufactured by Johnson Screens. Testing Contractor shall coordinate with plant operating staff to perform an air scour with the water level no more than 24 inches above the underdrains. This test is to observe the air distribution pattern to ensure all gaskets are in the correct location and have not torn, rolled or otherwise been damaged in the installation process as well as checking for any deformation of the underdrains. Contractor shall be responsible for correcting deformations, gasket leaks, etc., prior to placement of media. Media placement Contractor shall provide and place new media in the Filter #1 Basin in the following order: Garnet Gravel, Garnet Sand, Silica Sand and finally Anthracite. All individual filter media layers must be level before moving onto the next layer. A filter backwash must be performed after the Silica Sand is added and before the Anthracite is added. For additional information, submit questions only via email to officemgr@athenstxwater.org. The Athens Municipal Water Authority reserves the right to reject any/or all bids and to waive formalities. If you have any questions or need additional information, contact: Mike Finney, City of Athens Water Superintendent mfinney@athenstx.gov Question Deadline 08/21/2023