Water district makes itself ‘at home’
At first glance, 8815 West Spring Mountain Road looks much like any other upscale suburban home in the Las Vegas Valley. However, despite the stucco walls, tile roof and landscaped lawn, the house is anything but typical.
First, there is the price tag: $25 million; and second, there is the fact that, instead of appliances and furnishings, the structure is filled with electrical wiring, pumps, motors, valves and flow monitoring systems. Situated in a residential area, the house is actually home to the Las Vegas Valley Water District’s (LVVWD’s) Spring Mountain-Durango pumping station and reservoir.
Designed by Montgomery Watson, Pasadena, Calif., the facility has a maximum pumping capacity of 155 million gallons per day and a storage capacity of 35 million gallons. It is LVVWD’s largest pumping station, serving 130,000 residents, and it is a key element in securing the district’s future water transmission.
The plant represents the culmination of a three-year relationship with the Spring Valley community, which worked with LVVWD to ensure that engineering and aesthetics were balanced. “[The project] has literally transformed how we communicate with those we serve,” says Thomas Minwegen, engineering director for LVVWD. Located in Clark County in Southern Nevada, LVVWD serves nearly 800,000 people in the city of Las Vegas and nearby unincorporated areas. In the last three decades, the region’s population has more than tripled.
Since 1980, the Spring Mountain site has supported a 14.4-mgd pumping station and a 20-million-gallon reservoir. Pumps have been added to the facility periodically to meet growing demand; however, by late 1995, the station needed a major expansion.
“We applied for a land use [zoning] change to the existing facility parcel as a means to inform the surrounding community of our intentions through an established public hearing process,” Minwegen says. In the weeks preceding the public hearing, LVVWD officials met with members of the community to share the conceptual expansion plans and inform residents of the public hearing process. The response was less than favorable. Many homeowners did not know who owned the property near their homes, and they were unfamiliar with the city’s zoning guidelines. They felt hoodwinked by homebuilders and LVVWD, and they objected and threatened lawsuits.
Because of the limitations imposed by the existing distribution system and the elevation necessary to ensure proper hydraulics, the district did not have a feasible alternative site for the pumping station. “Bottom line: We needed to further expand [the Spring Mountain] site,” Minwegen explains. “But we also felt it our responsibility to ease the concerns of the local community.”
Intent on gaining public endorsement of the project, LVVWD arranged a series of public meetings in which key members of the project team, including the architects and a Citizens Design Review Team (CDRT), gathered to discuss the expansion. Consisting of members of the Spring Valley community, the CDRT was guided by three citizen-appointed chairmen.
Residents of Spring Mountain were adamant in their refusal of any design that resembled the traditional monolithic water pumping station. Therefore, the project team met repeatedly to rework the design so that it was aesthetically pleasing as well as technically sound. “We already [knew] how to build pumping stations very well,” Minwegen says. “How hard could it be to hide the facility behind a nice facade?”
The community requested that LVVWD keep much of the new facility – including pump and motors – below grade. Ordinarily, pump motors are located within sight of the electrical switchgear so the operator can turn switches on and off while observing the equipment. Although the pumps and motors could be located below grade, the station’s switchgears could not, prompting engineers to pro-pose a structure “no bigger than a house” to conceal the switchgears.
In the end, 13 horizontal, split-case centrifugal pumps (placed in a structure measuring 374 feet by 89 feet) were buried 30 feet below the surface. The substructure, including the reinforced-concrete reservoir, is longer than a football field. LVVWD installed video cameras to monitor the below-grade equipment, and the station operator can observe the video images from the upstairs switchgear facility.
In addition to the switchgear house, LVVWD constructed two evaporative cooling structures, an electrical substation and a sodium hypochlorite storage facility on the site. All of the buildings were designed to blend into the residential setting.
The district also took steps to control noise and vibration that could potentially disturb residents. The pumps’ foundations were designed to minimize the transmission of vibration to the ground, and sound was contained by placing the pumps in the basement and covering basement walls and some surface buildings with acoustical sound panels. Additionally, acoustical air vents were used to minimize the sound being transmitted through the pumping station’s ventilation system.
Construction of the Spring Mountain-Durango pumping station was completed in spring 1999. “We learned a lot during this process, and the end result is a facility that meets the needs of our community in all respects – a facility that everyone is proud to have in his own backyard,” Minwegen says.