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City of Everett,Washington I Water Filter Plant- Phase 2 Capital Upgrades PDB Project <br /> Progressive Design-Build Contract I Exhibit B.Owner's Project Criteria <br /> ability to isolate the outlet weir gates for maintenance and replacement should <br /> be considered in this work. <br /> • Maintain flocculation basin overflow weir operation and overflow weir <br /> hydraulic capacity consistent with existing overflow weir. <br /> • Incorporate plans for future connection to additional flocculation channels with <br /> minimal modifications required to the outlet channel(s). Future additional <br /> flocculation channels will likely be constructed north of the existing <br /> flocculation basin parallel to the existing channels. <br /> • Incorporate plans for future connection to redundant flocculated water <br /> pipeline with minimal modifications required to the outlet channel(s). Future <br /> redundant flocculated water pipeline will likely be constructed parallel to the <br /> existing flocculated water pipeline. <br /> Flow to, and through the flocculation basin must be maintained during this work. It's <br /> anticipated this work will be performed through bypassing sections of the flocculation <br /> basin via the existing gates and additional temporary measures. <br /> Alum and Polymer Storage Tanks Replacement: Condition assessment of the <br /> chemical storage building found that the bulk alum and polymer storage tanks have <br /> exceeded their useful service life and show signs of deterioration. Additionally, <br /> evaluation of the bulk storage tank sizing found that both the existing alum and polymer <br /> storage tanks exceed the storage volumes required for plant operations over the next <br /> 20 years of anticipated production. The City intends to remove the existing alum and <br /> polymer storage tanks, replace them with new tanks, install new level sensors, and <br /> replace the associated chemical piping and delivery systems co-located in the chemical <br /> storage building. <br /> Recommendations in the WFP Facilities Plan include replacement of the two existing <br /> 31,300-gallon polymer storage tanks and two 29,800-gallon alum tanks with smaller <br /> vessels. Preliminary sizing estimates that two 25,000-gallon alum storage tanks and two <br /> 13,000-gallon polymer storage tanks will provide the necessary storage volume required <br /> to meet production needs through 2040. Planning level budget assumes each of the <br /> four replacement tanks will be fiberglass construction and installed with ultrasonic level <br /> sensors. Removal of a portion of the chemical storage building is required to remove <br /> and replace the storage tanks and approximately 3,200 sf of building siding and spray <br /> foam insulation is anticipated to be replaced following tank installation. The Design- <br /> Builder shall perform all necessary calculations to size and design chemical storage <br /> tank and chemical delivery system improvements. <br /> Full time use of these chemicals is required 24/7/365, thus it is anticipated that this work <br /> will include temporary facilities/piping in order to maintain full operations of the Filtration <br /> plant. <br /> Hydrofluosilicic Acid (Fluoride) Storage Tanks Replacement & Fluoride Building <br /> HVAC Improvements: Condition assessment of the WFP fluoride system indicated that <br /> the two 6,500-gallon bulk hydrofluosilicic acid (fluoride) storage tanks have exceeded <br /> their useful service life and need replacement. In addition to tank replacement, the City <br /> Page 6 of 16 <br />