ATTACHMENT C

OWASA Water Demand Projections

Basic Assumptions and Information Sources

(The following assumptions and information were used to generate demand projections in March 2005.  Modifications will be made, as appropriate, when revised projections are produced in the near future.)

1. Water sales to all non-UNC customers were assumed to increase at a constant rate of 0.145 mgd/year, which is intermediate between the historic rate (1980-2002) of 0.1907 mgd/year for all OWASA customers and the long-term projected rate of 0.106 mgd/year with passive conservation, assumed in Technical Memorandum 3.3 of the 2001 Comprehensive Water and Sewer Master Plan.  Staff believes that the 0.145 mgd/year rate reflects a degree of permanent conservation that has occurred during recent years.  

2. UNC Main Campus demand assumptions were based on Brown & Caldwell’s 2002 UNC Water and Sewer Master Plan, which contains specific Main Campus demand forecasts for 2008 and final buildout, for which no fixed date was specified.  OWASA’s demand forecasts assumed that Main Campus buildout will occur in 2026, which is the same assumption used in our previous demand forecasts.  It should be noted that UNC Main Campus demand projections were subject to a higher degree of uncertainty than other customer classes, due to the intense level of facility construction and rehabilitation either planned or underway, as well as the dynamic nature of the University’s development process. 

3. UNC Carolina North demands were based on building category estimates of the Ayers/Saint Gross Carolina North Master Plan and water usage factors of the 2002 Brown & Caldwell UNC Water and Sewer Master Plan. Carolina North water use was assumed to begin in 2008 and to increase by 0.037 mgd/year until buildout, which was assumed to be in 2050.  However, specific plans for Carolina North remain highly uncertain.  Although we anticipate that highly treated wastewater will be reused for non-potable purposes at Carolina North, that assumption has not been applied to current projections; i.e., current projections assume that no reuse will occur Carolina North.

4. Projections for non-potable water reuse on UNC’s Main Campus were based on University staff’s best estimates for reclaimed water demands for four individual chiller plants.  The reuse system was assumed to begin operating in FY 2008.  The Lesser Reuse projections include currently programmed uses that were expected to reach 0.9 mgd by 2026 and, include only the four existing chiller plants located on the south side of the campus. The More Reuse projections include approximately 1.0 mgd of additional demand for other facilities and uses (Cogeneration Plant cooling towers and boiler makeup, new Northeast Chilled Water Plant, new Manning Drive Steam Plant, existing UNC Hospitals chilled water plant, and irrigation of certain athletic fields), but plans and commitments for these have been less definite.  (Note: revised reuse forecasts that were provided by the University in September 2005 are not reflected in the numbers discussed above.)

5. All Raw Water Equivalent demand forecasts assume an “unbilled” treated water fraction of 10 percent; i.e., OWASA pumps and treats 10 percent more raw water from our reservoirs than is accounted for in metered billing records.  The raw water projections assume that treatment plant process water at the Jones Ferry Road Water Treatment Plant continues to be fully recycled and not discarded.