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

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Mountain Home Water Facilities Planning Study Update October 2019
will inevitably take place. Maintaining the plan and the planning tools will serve as the most effective
means for the city to proactively manage this crucial component of their existing infrastructure.
4.7 DECLINING BALANCE SUMMARY
4.7.1. Remaining Capacity
Calculations of remaining capacity for the system can be found in Appendix C. The
remaining firm capacity of the water system was estimated to be approximately 1,850
additional equivalent dwelling units (EDUs) before needing additional well supply in service.
This corresponds to a City population of 18,460. With the addition of a new 1,500-gpm well,
the water system would have an estimated remaining capacity of approximately 1,586 EDUs
(population 22,060).
For continued growth in the system, additional wells will be needed every 1,580 EDUs. If
the City supplies newly constructed wells with backup power, it is not anticipated that the
City will need additional storage within the 20-year planning period. Additional details on the
timing of these recommendations are included in Appendix D. Because it sometimes takes
years to permit, fund, design, and construct necessary improvements, Keller Associates
recommends that the City begin implementation of improvements well in advance of when
they are required.
4.7.2. Booster Station Considerations
Keller Associates also reviewed data for the upper and medium pressure zones to assess
available booster station capacities (see Appendix C).
In estimating the remaining capacity of the upper zone, the use of Well 14 (which can be
manually directed to the upper zone) was not considered in approximating the firm pumping
capacity. Additionally, in estimating remaining capacity of the medium pressure zone, the
existing PRV that services the zone was assumed to provide the firm backup supply of the
zone.
Based on this analysis, the medium pressure zone can add a total of approximately 318
EDUs before the booster pumping capacity at the booster station needs to be increased.
The upper pressure zone can add a total of approximately 240 EDUs before the booster
pumping capacity at the booster station needs to be increased. If Well 9 is used to supply
water to the medium pressure zone, listed as a priority 2 improvement in the recommended
CIP, it is anticipated that the zone can accommodate approximately 865 EDUs.
System
Wide
Pressur
e Zones
Table 4.4 – Declining Balance Summary
Improvement
Available
EDUs*
Approx.
Service
Population
Existing Condition 1,850 18,460
New Well 17 (1500 gpm) 3,436 22,060
New Well 18 (1500 gpm) 5,022 25,661
Additional Transmission varies varies
Medium Zone
Additional Pumping Capacity
318 NA
Upper Zone
Additional Pumping Capacity
240 NA
*Available EDUs is based on current number of users and is not adjusted to reflect vacancy rates, buildable lots,
or undeveloped land within the city limits.
CITY OF MOUNTAIN HOME | KA 214010-020 34