2007/06/20 Council Agenda Packet

C was assumed that the pipe would be maintained in service while exposed and supported in the construction zone for up to 3 months during the CFDS construction. Following Carollo's internal QA/QC review and consultation with the City, it was determined that this design approach presented significant risk to the City's water supply due to the potential for loss of water supply in the event of a construction accident. Therefore,.Garollo developed an alternate design detailing a 60-inch "bypass" around the CFDS directly to Clearwell No. 2. The bypass would be installed prior to the construction of the CFDS using a "hot tap" methodology,which allows the plant to remain on-line during its construction. Once in place, filtered water would be conveyed from the filters directly to Clearwell No. 2, allowing the filtered water pipeline to Clearwell No. 1 to be taken out of service. This allows the Contractor to construct the CFDS without concern with regard to loss of water supply during construction due to the exposed filtered water pipeline, and provides the City with a significantly lesser degree of risk that the water supply would be lost during construction. Electrical Improvements Project modifications included the replacement of pole-mounted transformers with pad-mounted transformers at both the BWPS and the Reclaimed Water Pump Station(RWPS). New panels and pump station controls were provided at both locations. Additional drawings included one- line, plan drawing and control schematics, and modifications to the project site plan, details, and panel schedules. While replacing existing conduit that passed through the new clearwell site, the Engineer was directed to design a buried primary power conduit encircling the site. The redesign of the BWPS included multiple sample pumps and water quality analyzers,with conveyance of water quality data to the Operations Building. Miscellaneous Design Components There were other additional scope items that were not originally anticipated, including: • Contract Documents and Schedule. The design fee estimate assumed a total of 67 drawings for the project. Due to the increased project complexity and additional scope items, 99 drawings were required for the project. In addition, the project schedule increased significantly over the project life to incorporate the design changes. • DOH Report. Preparation of a Design Report for the Washington Department of Health (DOH). • 5-line Control Valve. Although not included in this design, significant effort was expended to design a control valve that would allow a portion of the 5-line to be isolated, in accordance with a DOH request. During the preparation of this design, a more simplified approach was developed, and the work will be completed under a separate contract. H:\Client\Everett_SEA\Contrails\7094A10-Clearwell dgdn\Amend 1 Apr 2007\EXHIBIT A doc '� 1• A-3