Nestled among the pine trees of Arkansas lies the picturesque town of El Dorado. The forests, parks and wildlife maintained by the city makes this municipality a highly coveted place to live as well as visit.
However, El Dorado, much like other cities across the nation, has experienced increased water demand in recent years. When coupled with drought, such growth can strain the water supplies of small cities.
El Dorado obtains its municipal source of water from the El Dorado Aquifer of the Sparta Formation. With municipal and several industrial wells located in the central portion of El Dorado, replenishment times for these wells were affected to a point that demand exceeded supply.
"El Dorado's water wells in the downtown area were simply built too close together," said Craig Johnson, P.E., Project Manager at Carter-Burgess, Inc., a firm specializing in planning, engineering, architecture and construction management. "With the close proximity of the wells, the aquifer could not replenish quickly enough to meet the city's water demands during peak months."
In order to ensure municipal water requirements were met, the city of El Dorado contracted with Tanner Engineering and Carter-Burgess to design five new deep wells, water transmission mains, ground storage tanks, pump station, and chlorination facilities.
The municipality and engineering firm decided to save time and energy by installing a modular pumping system. The system would draw water from a pair of two million gallon ground storage tanks filled by the new wells and deliver it to the city's distribution system.
"We met with representatives from a Dallas-based modular manufacturing firm, Flowtronex, and explained the situation," Johnson said. "One week later, their reps presented a CAD drawing with a proposed layout that would enable us to lay the ground work for the design process. Historically, the size and pumping capacity we needed was met with a site-built station. But, Flowtronex was able to meet our needs and most importantly meet our deadlines and budgeting constraints with one of their modular products."
The assembled modular station's skid measures 16 feet by 58 feet and is open faced with 10 inch channels and open I-beams. The top of the skid was placed at the finish floor elevation and the open I-beams were filled with concrete to control vibration. Flowtronex provided detailed CAD drawings in advance. The engineers were able to design around the system, which included support piping, equipment, building layout, and conduit stub-out locations. The design process allowed the contractor to prepare the building and support components while the system was manufactured at Flowtronex, thus saving time.
The station has an outflow capacity of 8,000 gpm and its pipe system is internally lined with fusion-bonded epoxy, which meets AWWA standards. The station contains smart motor controllers to avoid pipe surges and water hammer at pump start-ups and shutdowns, which enhance the system's longevity. The station, which is designed for future expansion, is outfitted with a surge anticipator valve between the suction and discharge headers and was designed on the same centerlines of the existing pumps on the station. In the future, the surge valve can be re-located downstream and another pump can be moved into its place on the skid.
Transportation Limitations
Because the system's size is limited to what can be transported on the road, the complete 16 foot by 58 foot skid was designed and built so that it could be broken into six sections.