Montebello Filtration Plant II Emergency Filter Repair

Johnston Construction Company

• Completed comprehensive rehabilitation of five filter cells, including removal of the existing filter media, removal and disposal of the existing clay and plastic-tile underdrain systems, removal of deteriorated grout, preparation of the filter beds, and installation of new filtration components. The City’s agreement specifically required repair of five rapid gravity filters, installation of new stainless-steel underdrains, and installation of new filter sand.
• Furnished and installed a new Tonka Water BLEU stainless-steel underdrain system in all five filters. The BLEU system utilized a low-profile, dual parallel-lateral arrangement designed for existing concrete filter installations and incorporated stainless-steel laterals for distribution and collection beneath the replacement media.
• Removed and replaced the filtration media throughout all five filter cells. The project specifications called for approximately 20 inches of filter sand in each gravity filter, with each filter consisting of two bays measuring approximately 13.5 feet by 53.5 feet, or roughly 1,444.5 square feet per filter. JCC coordinated media placement, leveling, backwashing, and preparation for return to service.
• Rehabilitated the existing surface-wash system serving the filters, including removal of existing sweep rotating arms and sweep-header piping followed by fabrication and installation of new drop-down piping, new surface-wash header piping, and new sweep rotating arms. The contract schedule of values included work on approximately 40 rotating sweep arms across the five filters.
• Installed airwash improvements for the rehabilitated filters. The contract included airwash laterals for all five filters, with laterals capped and buried within the media in four filters and one filter connected to a new air header, providing infrastructure for enhanced filter-cleaning capability.