Montebello Filtration Plant II Emergency Filter Repair

Key Accomplishments

• 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.
• Performed extensive structural and concrete rehabilitation within the filter cells. Work included repairs to vertical spalled or hollow concrete surfaces, horizontal concrete repairs, crack repairs, sealing of cold joints and trough-to-wall joints, re-leveling grout on filter beds, and preparation of deteriorated concrete surfaces before recoating.
• Repaired and recoated approximately 5,318 square feet of filter-wall surfaces and the concrete filter troughs. The rehabilitation incorporated specified concrete resurfacing and protective coating systems to restore deteriorated surfaces and provide durable protection within the continuously wet filter environment.
• Included a specialized Xypex crystalline concrete-treatment contingency where required by the condition of the existing concrete. The system was intended to address concrete requiring additional waterproofing treatment beyond the conventional resurfacing and coating system, with repair preparation including cleaning, removal of deteriorated material, crack and defect treatment, and application of the crystalline coating system.
• Managed construction within an operating municipal drinking-water treatment facility. JCC isolated filters under rehabilitation from filters remaining in operation, installed dust-suppression measures, controlled demolition debris, and coordinated access and dewatering so rehabilitation activities could proceed while protecting adjacent operating treatment systems.
• Managed the required engineering submittal and closeout process, including shop drawings, product data, field-coordinated installation drawings, approved equipment documentation, record information, and operation-and-maintenance manuals for permanent equipment and systems incorporated into the completed work.
• Johnston Construction Company served as the Prime Contractor for the Montebello Filtration Plant II Emergency Filter Repair project for the Mayor and City Council of Baltimore, acting through the Baltimore City Department of Public Works. The work was performed at Montebello Filtration Plant II in Baltimore, Maryland, under Contract WC-1362.
• JCC’s work involved complete rehabilitation of the five affected rapid gravity filters. Initial activities included isolating the work areas from operating filters, implementing dust-suppression measures, removing the existing sweep assemblies and associated piping, removing the existing filter media, demolishing the existing clay and plastic-tile underdrain systems, and removing deteriorated grout from the filter beds.
• Following demolition, JCC repaired and prepared the existing concrete filter structures. The work addressed vertical and horizontal spalling, cracks, cold joints, trough-to-wall joints, irregular or deteriorated grout surfaces, filter walls, and concrete troughs. Damaged concrete was repaired and resurfaced, followed by application of the specified protective coating systems. The project also incorporated a Xypex crystalline treatment option for concrete requiring additional waterproofing rehabilitation.
• A major component of the project was replacement of the original filter underdrains with the Tonka Water BLEU stainless-steel underdrain system. The system consisted of low-profile stainless-steel dual parallel laterals installed across the filter floors. The product was specifically designed for new and existing concrete filter systems and provided media-retaining distribution laterals beneath the filter bed.