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UNC, OWASA to partner in building water reuse system

The Orange Water and Sewer Authority (OWASA) recently approved a contract with the University for the financing, construction, operation and maintenance of a water reuse system.

Reuse refers to the use of highly treated wastewater for non-drinking purposes such as operation of cooling towers, irrigation and toilet flushing.

Like other forms of drinking water conservation, water reuse will:

  • Reduce the demand for drinking water;
  • Reduce the community’s risk during severe droughts and other water supply emergencies;
  • Extend the sufficiency of OWASA’s high quality, locally protected drinking water supply sources (the Cane Creek Reservoir and University Lake); and
  • Help defer or eliminate the need to develop or expand costly drinking water supply and treatment facilities, thereby providing long-term savings for the community.

The reuse system will initially carry highly treated water from OWASA’s Mason Farm Wastewater Treatment Plant in the southeast part of Chapel Hill to the southern campus area near Manning Drive and Skipper Bowles Drive.

The University has been installing reclaimed water pipeline on its property along with its other utility infrastructure projects in anticipation of the approval of this contract, and a reclaimed water storage tank was included in the concept plan the University submitted to the Town of Chapel Hill in early April.

This submission was part of the University’s proposed modification to its development plan with the town.

The overall amount of water use by OWASA customers will drop when the reuse system comes on line. That will affect OWASA’s drinking water revenues and rates somewhat, but the long-term effect will be savings to customers through reduced or deferred needs for water system capacity expansions.

The University plans initially to use reclaimed water instead of OWASA drinking water in cooling towers at its chiller plants by 2008. The initial water savings from reuse will be about 530,000 gallons per day or 6 percent of the community’s total drinking water demand. The long-term reduction in the community’s total water demand resulting from reuse on the main campus is projected to be about 13 percent.

OWASA will own the reuse system and will have the sole authority to set the rates and fees for water reuse service. The rates and fees will reflect the actual cost to operate, maintain and manage the water reuse system.

The estimated cost for design and construction of the first phase of the reuse system from the Mason Farm Wastewater Treatment Plant to the southern part of the University campus is about $11 million. The University will finance all of these costs, except for $2.5 million to be covered with approved state and federal grants. Future phases could extend the system to the northern part of the campus at an estimated additional cost of about $3 to $4 million. The University would also pay for future phases on campus.

The University will pay for the costs to operate, maintain, extend, enlarge and manage the reuse system that will serve campus. The reuse system can be extended in the future to serve additional customers, who would pay for all costs of reuse service to them.

OWASA and UNC did a special study in 2004 to confirm that the quality and disinfection of treated wastewater will meet state standards for allowable reuse purposes and will provide a high level of protection of public health. This microbiological analysis was done by a member of the University’s environmental sciences and engineering faculty who is a nationally recognized expert. The microbiological study concluded that with the planned treatment system, pathogens will be reduced.

Wastewater is disinfected with ultraviolet light as part of the treatment process, and chlorine will also be added to reuse water before it goes into the reuse system to maintain disinfection during use.

The contract commits the University to using reclaimed water instead of drinking water in certain cooling tower operations.

A summary of the proposed contract is available in the water reuse section of the OWASA web site.

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