214010-020-mtn-home-2019-10-31-wfps-report

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Mountain Home Water Facilities Planning Study Update October 2019
Storage Shortfall
Keller Associates recommends that all future wells be outfitted with onsite backup power
generators. Doing so will decrease the DEQ emergency storage requirement for the City,
thus dropping the overall storage required.
Due to the recent construction of Tank 1B, it is not anticipated that the City will require an
additional storage tank prior to 2040 if future wells are equipped with standby power.
Towards the end of the 20-year planning period the City should begin considering adding
additional storage capacity. Keller Associates recommends that the location and size of
future storage facilities be reevaluated in future planning efforts. The optimum storage size
and location will be a function of many parameters (i.e. growth rates, location of
development, well locations, remaining life and condition of existing facilities, and available
transmission). A second storage facility at the Tank 2 site or replacement of the Tank 2
should be one of the options considered in future planning efforts.
Pumping Delivery Shortfall
Complete pipeline improvements that will allow Well 9 to pump directly to the medium
pressure zone. If additional fire protection is needed in the upper pressure zone in the future,
upsize the Pilot Booster pumps at that time.
Fire Flow Shortfall
The distribution pipeline improvements necessary to correct the fire flow shortfall were
identified in Chapter 3 and will be included as part of the capital improvement plan. The
immediate need of ISRB deficient structures will be met by implementing Priority 1
improvements. Priority 2 improvements will resolve commercial and residential area fire flow
deficiencies. Phasing for these improvements along with other future improvements are
illustrated in Figure 4.1 of Appendix A. The City should be aware that notification of those
residences not meeting minimum fire flow requirements may be required until such time that
adequate fire flows can be provided. The type and frequency of notification will need to be
coordinated with DEQ.
High System Pressures
Outfit future wells with VFDs to maintain desired hydraulic grade in the system. Additionally,
require pressure regulators on new services where system pressures have the potential to
exceed 80 psi, with approval from DEQ.
Low System Pressures
Complete the Priority 1 improvements, including the installation of isolation valves that alter
the medium pressure zone to encompass the existing low-pressure areas. Complete
additional transmission pipeline improvements as required for new developments.
Future System Improvements
As the City continues to grow, it is important to ensure the water system grows in a planned
manner with appropriate transmission and distribution sizes. It is recommended that the
minimum line size allowed in the system be 8 inches in diameter. Figure 4.1 in Appendix A
illustrates the proposed layout for larger transmission lines. Many of the transmission
pipeline improvements within the City could be coordinated with roadway projects. Because
the need for these future lines is likely to be driven by development and will also likely occur
beyond the current 20-year planning window, only the upsize costs (portion likely to be paid
for by the City) have been included as part of the Capital Improvement Plan. Computer
model evaluations should be completed with each new major development to ensure that
adequate infrastructure is in place for the development.
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