2011/09/21 Council Agenda Packet

keylnea� .Q 6 � � t�,.�or-k, Exhibit A-4 Scope of Services: Task 600 Additional Surge Analysis AWD 401-05 Pump Station 1 Upgrade Alderwood Water and Wastewater District The following proposed Scope of Services is in response to Alderwood Water and Wastewater District's (AVVWD's) request for Kennedy/Jenks Consultants (Kennedy/Jenks)to provide services to evaluate surge conditions involving AVVWD's Pump Station 1 (PS 1), Pump Station 2(PS 2), and the City of Everett's (City's) Evergreen Way Pump Station (EWPS). Surge analysis is included within the current contract. This existing scope is limited to the discharge side of PS 1 and PS 2. The surge analysis to be provided under this scope of services will evaluate the suction side of the three pump stations, the City's Reservoir 3, and associated piping. Scope of Services The engineering services to be performed during the construction period are in accordance with the current project schedule (Exhibit C-4 attached). The proposed services include transient flow modeling by Flow Science (existing subconsultant) and supporting efforts by Kennedy/Jenks. Task 600 —Additional Surge Analysis Task 610 — PS 1, PS 2, and EWPS Suction Evaluation Task 610.1 Preliminary Concepts Technical Memorandum Surge evaluation efforts previously performed under this contract considered conditions in the AVVWD distribution system downstream of PS 1 and PS 2. The impact of potential surge events on the system upstream of the pump stations was specifically excluded due to its dependence on the operation of the Reservoir 3 and EWPS. A technical memorandum will be prepared to identify potential surge concerns, and to determine whether further evaluation is warranted. The memorandum will include a schematic diagram of the system, a table summarizing potential hydraulic concerns, and a brief memorandum. The memorandum will be submitted to AVVWD and City for review. The memorandum will address what evaluations, including the use of system modeling, are recommended to be completed. Task 610.2 Surge Evaluation The hydraulic transient analysis model previously developed by Flow Science for PS1 and PS 2 will be modified to include the operation of-theEVVPS,"-Berry-Line and- eservbir -:-Ttie.revised-model will be used to evaluate surge conditions caused by various operational conditions at the pump stations. Up to 5 scenarios will be analyzed using the model. The results of the analysis, along with possible measures to mitigate surge affects, will be presented to AWWD and the City in a meeting. Task 610.3 Findings and Recommendations Technical Memorandum q, t�t rilevO itte rcL A/v, 2. 1 • 26