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A Case Study: Updating a Postwar-Era Potable Water System

The Foss Reservoir Master Conservancy District (FRMCD) in southwestern Oklahoma is part of the 8,800-acre Foss Reservoir/Foss Lake. The treatment plant, which is located adjacent to the Foss Dam, pumps water from three pumping stations through 50.8 total miles (81.8 kilometers) of concrete transmission lines. The system was put in from 1958 to 1961 and was in need of an update so that FRMCD could better serve its 17,000 consumers in several towns.

Problem

The concrete bar-wrapped tongue-and-groove pipe transmission lines that carry water to these towns were aging. Like many government-constructed water distribution systems developed in postwar years, FRMCD sorely lacked funding to install main valves in their systems to isolate the towns the district served. With the passage of time, erosion of the concrete pipe caused leakages.

High pressure and reverse flows caused fittings failures; and, until recently, whenever a leak occurred, standard operating procedure meant shutting down the entire system to make repairs. A more effective alternative was needed for uninterrupted water delivery.

SOLUTION

Beginning in late 2013, pipeline repairs were made at FRMCD that included installing 18-, 24- and 30-inch 150 psi butterfly isolation valves at each point where a line enters a city. Designed specifically for the waterworks industry, the butterfly valves were made to be rugged and reliable for buried service. The body-mounted elastomeric seat had ridges that provided multiple sealing lines and permitted higher levels of radial compression. As a result, stress in the seat material was reduced, allowing lower seating torques and optimal sealing action.

The aging water towers and water storage tanks at FRMCD also required periodic maintenance, requiring shutdown of each tower’s individual supply lines and emptying of the particular vessel. In addition to valve installations at locations where water mains route to the towns FRMCD served, valves also were installed at tees within concrete vaults where transmission lines lead to water towers and tanks. This arrangement permits continual flow of water throughout the rest of the system while supply lines to and from each vessel can be independently closed as needed.

AN ADDITIONAL CHALLENGE

In the past two years, the areas surrounding the reservoir have been plagued by drought, causing a significant portion of Foss Reservoir to run dry. The lake currently is about 16 1/2 feet (5 meters) low and only one of the four intakes is supplying water. Naturally, greater control of water delivery to consumers within the system has become even more critical. However, the system improvements put into place for this update meant no customer is currently without water in the district.

Another significant benefit of this update has been that, even though many projects of this type have required procurement of special projects funding to make repairs and improvements, this update project has been completed on a routine, scheduled basis under the maintenance category, which means funding comes out of the existing maintenance budget.

CONCLUSION

All design and project objectives of the repair and improvements program at FRMCD were met or exceeded. What’s more, turnaround times for repairs and installations have been short, and no problematic hitches in the program have occurred. Water is now flowing uninterrupted to FRMCD consumers even when maintenance is performed at points within the system. This kind of success serves as a good example for other water distribution systems that need improvements or updates.


Deron Austin is director of marketing and ­com­muni­cations, Mueller Co. (www.muellercompany.com). Reach him at This email address is being protected from spambots. You need JavaScript enabled to view it..


REFERENCES

  1. Department of the Interior, Washita Basin Project, 2013
  2. Bureau of Reclamation, Washita Basin Project and Foss Dam, March, 2014
  3. Oklahoma Department of Environmental Quality, Drinking Water State Revolving Fund, Amendment No. 1, Intended Use Plan, March 2014

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