Filter Media Rehabilitation 1.0 Description. The contractor will be responsible for full rehabilitation of the filters as specified herein. Four of the filters (1, 2, 3, and 6) were recommended for rehabilitation. All filters are equally accessible and are of identical size. The City will determine which filter(s) are to be rehabilitated upon contract award. Complete rehabilitation shall include: • Engineering and material submittals • Removal and proper disposal of the existing filter media • Inspection and NSF-approved cleaning of the underdrain, trough, and walls • Complete disinfection of the unit per AWWA standards • Furnishing and installation of the new filter media • Start up and after-action report 2.0 Materials. The filter media shall meet the following specifications: • Filter Sand 0.45-0.55 mm UC 1.30 475 cubic feet (24 inches) • 0.08-1.20 mm Torpedo Sand 59 cubic feet (3 inches) • 3/16” x #10 Cap Gravel 59 cubic feet (3 inches) • 3/8” x 3/16” Support Gravel 59 cubic feet (3 inches) • ¾” x 3/8” Support Gravel 59 cubic feet (3 inches) 3.0 Payment. All labor; equipment, mobilization/demobilization, material, and freight costs associated with complete Filter Media Rehabilitation in accordance with this specification shall be included in the unit price per each filter media unit. Filter Media Cleaning & Top-off 1.0 Description. The contractor will be responsible for cleaning the existing filter media and top-off as specified herein. Filter units 4 and 5 were recommended for cleaning and topoff. Both filters are equally accessible and are of identical size. Media cleaning shall be done in-situ using NSF-approved chemistries for potable drinking water. This work shall include: • Complete filtration assessment • NSF-approved filter wall and trough cleaning chemistry • NSF-approved dual media and filter underdrain cleaning chemistry • Skimming of media • Complete disinfection of the unit per AWWA standards • Pre- and post- media cleaning testing and after action report 2.0 Payment. All labor, equipment, mobilization/demobilization, material, and freight costs associated with complete Filter Media Cleaning & Top-off in accordance with this specification shall be included in the unit price per each filter media unit.
