Agmt10 West Yost Associates - Laserfiche WebLink

Browse Search

Recommendations will be made for any modifications to the existing system performance criteria, if needed. The recommendations will take into account land use-specific fire flow criteria, and the unique configuration of the City's distribution system. In addition, WY A will include a review of the City's existing reliability criteria and level of service goals for different emergency conditions, such as power outages, seismic events and other potential operational disruptions. WY A will work with the City to update reliability criteria and level of service goals, as needed. TASK 7.2 EVALUATE THE EXISTING SYSTEM WY A will use the existing demands developed in Task 5 and the calibrated hydraulic simulation model developed in Task 6 to assess the adequacy of the City's existing water system facilities to meet the system performance criteria developed in Task 7.1. The system analysis will include the following: Evaluate Pump Station and Storage Capacity: Evaluate pump station and storage requirements, comparing pump station and storage sizing with service standards identified in Task 7.1. Assess Svstem Peak Demand Hydraulic Performance: Use the hydraulic model to assess system hydraulic performance for peak demand conditions, comparing system performance with established level of service criteria in Task 7.1. Analysis will be performed using static (snapshot) evaluations for maximum demand day plus fire flows, and for peak hour scenarios. Evaluate System Emergency Reliability: Assess five emergency scenarios developed in consultation with the City. Five preliminary scenarios have been identified for evaluation: 1) Fire flow service with Bay Division Pipelines out of service (specific scenario (Bay Division 1&2, Bay Division 3&4 or all Bay Division Pipelines out of service to be selected during project; 2) Use of Glenwood PS to supply Easter Bowl zone if Edgewood PS out of service; 3) Service to Redwood Shores with SFPUC Topaz turnout out of service; 4 and 5) two storage scenarios, to be identified during project.. Evaluations will consist of desktop conceptual-level evaluations to evaluate alternative service, with confirming static hydraulic modeling runs, to confirm facilities sizing. Assess Water Ouality: Perform extended period simulation analysis for average day conditions or other lower demand condition where conditions are conducive to water quality problems (e.g. late fall conditions with lower demands but warmer temperatures, where potential for nitrification would be more likely), to assess areas within the distribution system with low chlorine residuals. Bulk decay curves developed in Task 6 will be used to estimate chlorine residuals. Evaluate operational strategies and/or structural fixes for reducing water age in reservoirs, where needed. Identify areas that should be focus for main flushing programs. Evaluate Pump Station Energv Use: Review pump efficiency test data and identify up to three most likely candidates for pump rehabilitation/replacement. For these facilities, use past pump efficiency tests, static analysis with hydraulic model, and historical billing information to estimate annual pump station electrical use and operational costs. Identify potential savings if more efficient pumps were installed. Assess pump replacement costs to determine which projects would provide the most benefit. Identify and Prioritize Svstem Improvements: Based on the results of the system evaluations, WY A will identify which existing facilities lack capacity, have insufficient redundancy, have water quality deficiencies or would not be cost-effective to operate to meet existing demands. WY A will then identify October 22, 2009 11