City of Morgan Hill Water System Master Plan 2017

2017 City of Morgan Hill

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CHAPTER 7 - EVALUATION AND PROPOSED IMPROVEMENTS

This section presents a summary of the domestic water system evaluation and identifies improvements needed to mitigate existing deficiencies, as well as improvements needed to expand the system and service growth.

7.1 OVERVIEW

The calibrated hydraulic model was used for evaluating the distribution system for capacity deficiencies during peak hour demand and during maximum day demands in conjunction with fire flows. Since the hydraulic model was calibrated for extended period simulations, the analysis duration was established at 24 hours for analysis. The criteria used for evaluating the capacity adequacy of the domestic water distribution system facilities (transmission mains, storage reservoirs, and booster stations) was discussed and summarized in the System Performance and Design Criteria chapter. The fire flow analysis consisted of using the maximum day demand in the hydraulic model and applying hypothetical fire flows. The magnitude and duration of each fire flow was based on the governing land use type within proximity to the fire location. The criterion for fire flows was also summarized in the System Performance and Design Criteria chapter. The hydraulic model indicates that the City’s existing distribution system performed adequately during the fire flow analysis. Areas where the City water system did not meet the fire flow criteria are documented on Figure 7.1 . The available fire flow at the City’s residual pressure criteria of 20 psi is summarized on Figure 7.2 . It should be noted that a majority of the service connections in the eastern foothills are unable to meet the pressure requirements under fire flow conditions. A majority of the distribution system serving this area is comprised of 6-inch and 8-inch water pipelines with minimal looping. It is recommended that as pipeline replacements occur, 6-inch pipelines be upsized to 8-inch pipelines to reduce the headloss and velocity impacts to this area. Additionally, where the cost is not prohibitive, it is recommended that looped connections be constructed for reliability. 7.2 FIRE FLOW ANALYSIS

Improvements to mitigate specific fire flow deficiencies are discussed below and include a corresponding coded identifier, which is consistent with the capital improvements chapter:

 NH-P2. Replace approximately 950 feet of 4-inch water main from Del Monte Avenue to Monterey Road along Spring Avenue with 8-inch water main.

 BR-P5: Replace an 8-inch pip with a new 10-inch pipeline in Mission View Drive between Cochrane Road and 2,100 feet northwest of Cochrane Road.

June 2017

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City of Morgan Hill Water System Master Plan