By Heather Mullinix
Crossville can extend its supply of drinking water several years without adding to the supply of raw water available in resevoirs by providing upgrades in staffing and facilities for water treatment plants and adding upgrades to other infrastructure, a report finds.
The report, prepared by GKY & Associates for the U.S. Army Corps of Engineers, is step two in developing a Cumberland County Regional Water Supply Plan and was presented to members of the Crossville City Council at a work session Feb. 5.
"We wanted to see how far we could extend the system if we were not increasing the yield by raising dams or building a resevoir," explained Stuart M. Stein, president of the Chantilly, VA water resources and environmental solutions company.
The study used population models of expected growth and historic rainfall data from 1913 to 2008 to determine the amount of water that would be available as the community continues to grow and developed six scenarios.
Without some action, the water supply is set to fail to meet demand by the year 2016, explained Aaron S. George, water resources engineer.
Scenario no. 1 lifts the capacity constraints of the water treatment plants, something the city will need to do regardless due to requirements of the Tennessee Department of Envionrment and Conservation. The Lake Holiday Water Treatment Plant has a current capacity of 2 million gallons per day, but that could be doubled by doubling the staffing of the facility. The Meadow Park Lake Water Treatment Plant has a current capacity of 3.5 million gallons per day and would require upgrades to the facility and additional staffing. This extends the life of the system to 2026, but fails to meet demand in 2036. That shortage occurs in the Crab Orchard Utility District, which is served by the Otter Creek Lake Water Treatment Plant. There is a treatment capacity of 4 million gallons a day.
If the city were to combine the water treatment plant upgrades and allow for removing institutional contraints on how much water can be provided other water districts, then system performance can be improved, but the system yield does not extend beyond the 2026 demand, with a shortage in COUD.
The engineers looked at improving infrastructure at physical connections to the South Cumberland Utility District and COUD individually and together. Just increasing the connection to SCUD does not alleviate system failure in 2036 in COUD, which continues to show a shortage. If the COUD connection were upgraded and a utility agreement in place to allow Crossville to transfer water to COUD, the system could meet demand to the 2036 benchmark year. Failure occurs in 2046, however, the shortages across the system in COUD, Crossville, SCUD, Fall Creek Falls and Grandview, and the water system would have only 45 days of water storage remaining in resevoirs.
If both the SCUD and COUD connections were upgraded to allow more water to flow between districts, water demand can be met to the 2036 benchmark year but there would be shortages by the 2046 year in COUD, Crossville, SCUD, Fall Creek Falls and Grandview, and only 45 days of water storage remaining.
Lake Holiday Water Treatment Plant has been serving a limited area of Crossville, but scenario six contemplates moving more water from that plant around the system. George said, "About 48 percent of the storage in Lake Holiday had been reserved in previous scenarios, but it taps out in this scenario."
The city could meet benchmark year 2056 demand, but the city would only retain 13 days of water storage. This scenario would require upgrades of Lake Holiday Water Treatment Plant and Meadow Park Lake Water Treatment Plant to handle at least 10 million gallons of water per day each. Otter Creek Lake Water Treatment Plant would need to expand to treat about 5 million gallons a day. COUD and the city would need to develop water transfer agreements and physical interconnections between the city and COUD and SCUD would need to be upgraded.
Stine explained this portion of the study did not contemplate new sources of water.
"We still have a ways to go," he told the council. "Just because scenario six meets the demand doesn't mean we should go with it. There are infinite possibilities. We had to start somewhere, though, and this was the easiest set of possibilities to evaluate."
Stine said the engineers will look at updated figures for water demand, consider conservation programs that could reduce demand as population grows.
After that data has been collected, alternatives will be added to the demand model, including raising the dams at Meadow Park Lake or Lake Holiday, or both, or constructing a new resevoir in the area to provide more water storage and more water to move through the system.
"We're not wed to anything yet," Stine said. "To this point, we needed to see where the water is really needed. The first area of need is going to be Crab Orchard."
Crossville Mayor J.H. Graham III said, "The biggest concern of every mayor in the Southeast is water. We are not going to be unprepared."