Laserfiche WebLink
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 /> intends to replace the fluoride building's HVAC system and replace the 1,000-gallon day <br /> tank used for mixing and dosing fluoride with a direct connection to the chemical <br /> metering pumps. Preliminary tank sizing estimates determined that replacing the two <br /> 6,500-gallon storage tanks in kind will continue to provide enough storage capacity <br /> beyond a 20-year planning horizon. <br /> Project planning level concept and budget assume removal and disposal of the existing <br /> cross-linked polyethylene fluoride storage tanks and day tank, installation of two 6,500- <br /> gallon polyethylene storage tanks with ultrasonic level sensing devices and <br /> reconfiguring the system piping to bypass the day tank. Replacement of the existing <br /> fluoride storage tanks requires the temporary removal of fluoride building roof sections. <br /> The Design-Builder shall perform all necessary calculations to size and design chemical <br /> storage tank and chemical delivery system improvements. <br /> Full time use of hydrofluosilicic acid (fluoride) is required 24/7/365, thus it is anticipated <br /> that this work will include temporary facilities/piping in order to maintain full operations <br /> of the Filtration plant. <br /> Clearwell Flow Diversion Structure (CFDS) Valves Replacement: A plant-wide valve <br /> condition assessment identified severe impairment in the operation of the one 72" <br /> diameter CFDS valve and three 84" diameter CFDS valves. The valves are buried <br /> approximately 20 feet deep (invert of valve) with no protective vaults or pile supports. It <br /> should be noted that the CFDS is supported by jet grout columns and the East Clearwell <br /> Control Structure is supported by stone columns. A desktop analysis carried out as part <br /> of the assessment identified that either the buried valve operators have seized due to <br /> corrosion or deformation of the valves has occurred due to settling. The City intends to <br /> replace all four valves and valve operators in kind and install seismically stabilized <br /> containment vaults to protect the valves and operators and improve access for future <br /> maintenance activities. The valves being replaced are V50, V51, V52, and V53 as <br /> shown in Figure 4. The City is open to alternates which may result in valves which are <br /> installed at much shallower depths. The existing valves connect to the adjacent pipes <br /> and flow diversion infrastructure using standard flange connections. The adjacent <br /> section of pipe attached to the valve connects to the next section of pipe using bolted <br /> split sleeve couplings. <br /> Flow from the Filter building to the City's Clear Wells must be maintained in order to <br /> supply water to the distribution system. Interruption of this flow may occur for very short <br /> durations after considerable coordination with multiple water purveyors that purchase <br /> water from the City. The East Clear Well can be taken out of service during this work; <br /> however, supply to the backwash pump station must be maintained. It is anticipated this <br /> work will be performed through bypassing sections of the system via the existing valves <br /> and additional bypass piping. <br /> Page 7 of 16 <br />