The existing Jess Ranch Lift Station was constructed in the late 1980’s to primarily service the Jess Ranch residential community to the south, which is directly adjacent to the Mojave River. Since that time, the community has grown significantly from approximately 46,000 in 1990 to 74,000 today as shown in the chart to the left and it’s estimated to exceed 76,000 by 2025. That growth is reflected with additional residential communities to the south as well as an expansive retail district to the north. Additionally, future development in the area west of Deep Creek Road has been identified that will also be serviced by this lift station. Additional proposed projects in that area have been conditionally approved necessitating an upgraded lift station to adequately service the area.
To implement the lift station upgrades, the Town retained LEE + RO to provide design alternatives followed by final design and construction support services for the selected improvements. A preliminary feasibility study was first prepared by LEE + RO to document and present constructible alternatives for the Town’s selection. The feasibility study included the design criteria, methodologies used, preliminary layouts, and opinions of probable construction costs for each alternative, one of which included the construction of a completely new lift station.
Upon selection of the Town’s preferred alternative, preliminary drawings, specifications, and cost estimates were further refined, and the final bid package was prepared. Construction of the new lift station began in June 2022 with an expected completion date of July 2023.
The project objective was to prepare design alternatives and form the basis of design to optimally increase the lift station’s existing capacity while simultaneously ensuring that the working pressure range of the existing dual 6-inch and 8-inch force mains that serve this station was not exceeded. Other objectives included provisions for ease of access for operational maintenance and integrating the design layout with the proposed future development of the area. These preconditions posed some unique challenges. This task was further complicated by the need for identifying optimal layouts and methods for achieving the improvements while also minimizing the duration the existing lift station would be taken out of service.
As upgrades to the existing dual force main were not included as part of this project, the existing force main’s capacity was identified as the limiting factor for determining the allowable pumping capacity increase for the lift station.
To determine the increase in allowable capacity, multiple system-pump curve analyses were performed by LEE + RO’s inhouse hydraulic modelers. The analyses identified the flow range and corresponding system pressures acceptable for safe operation of the aging force main. Upon identification of the acceptable flow range increase and resulting head losses required to be overcome by the new pumps, LEE + RO coordinated with local pump vendors to determine selection of the most optimal pumps and configurations.
To meet the new target capacity, LEE+RO recommended that a triplex station consisting of three (3) 25 horsepower pumps rated at 300 gpm each be used. This selection of a triplex station will allow the Town to maximize the lift station’s allowable pumping capacity in accordance with the existing force main’s design limitations and at the same time allow the Town to meet current low flow conditions with one only pump in operation.
In addition to upgrading the existing lift station configuration, LEE + RO also evaluated relocation options for a new lift station. Relocation of the new lift station allows the existing system to remain in service while the majority of the new lift station is constructed and reduces the overall shutdown duration for the cutover to the new system. Furthermore, relocation considerations also include providing additional distance from the nearby Mojave River, which increases the resultant response time for the Town in the event of a major catastrophic event such as flood or lift station failure.
Ultimately, a new location in accordance with future development plans was selected. Due to the Town’s desire to integrate the new location with the future proposed development, adequate solutions relied on LEE + RO’s unique layout configurations for the site. These configurations were required to properly locate the above-ground infrastructure in proximity to the new wet well. They also required corresponding valve vaults to eliminate excessive piping and conduit runs while retaining the future development areas clear for community use. These layouts were coordinated with the Town for their input and preferred alternative.
