The costs associated with the city's plan to meet future demands on wastewater treatment are staggering.
The costs for the city's two wastewater treatment plant alternatives range from $70.2 million to $75.8 million depending on which alternative the city chooses.
"The new system is expensive in part because it is not just an upgrade but an actual replacement of the existing system," said Betsy Roberts, an engineer with the city's contract engineering firm CH2M Hill.
The new treatment schemes that have been selected provide a higher level of treatment than the city now uses.
The effluent now produced by the city is suitable to be used to irrigate ranch land south of McCall.
The proposed treatments could, under one scenario, be used to irrigate the golf course
and other public facilities, Roberts said.
While the costs are high, Roberts notes they are preliminary figures for comparing the two alternatives.
Current estimates are $70.2 million for the river discharge alternative and $75.8 million for the rapid infiltration alternative.
Other, more expensive, alternatives were rejected earlier in the planning process, Roberts said.
"The final costs will vary from those presented during the planning phase as the project definition continues to evolve," she said. "At this level of definition the costs presented include contingency for unanticipated factors and conditions that are undetermined."
The cost of purchasing land has largely been removed as a factor from the river discharge alternative. But the city would need to buy 41 acres of land in the second alternative, which would allow wastewater to seep into the ground in basins.
The costs are highest during the first phase of the project due to the development of major infrastructure in either alternative, Roberts said.
After that, the phasing becomes less expensive as individual units, which increase capacity incrementally, are installed," she said. "In very general terms, the costs will be spread to allow future growth to pay for the majority of the expansion of the plant."
Aeration basins largest chunk of river-discharge option
Basins to mix air into sewage to speed digestion of waste are the largest part of the estimated $70.2 million cost of the river discharge option being considered by the city of McCall.
Of the total, $40.5 million would be spent on building four basins that would inject air into sewage to feed bacteria that in turn would eat solids, according to the city's engineers.
Major items that make up the bulk of the construction costs are:
• Two fine screens and two vortex grit removal devices: $7.4 million.
• Aerobic digestion: $7 million.
• A 4,000-square-foot administration building and support facilities: $4.2 million.
• Dewatering belt filter press: $3.7 million.
• Expanded capacity for sodium hypochlorite, a disinfecting
agent: $2.5 million.
• Pump station: $2.4 million. • Phosphorus reduction projects elsewhere: $2.25 million.
• Modification of the existing aerating lagoons: $250,000.
The project would be built in three phases over 20 years.
The first phase would be constructed from 2013 to 2017 and would cost $48 million.
The second phase, 2018-2023, would cost an additional $12.8 million.
The final phase, 2024-2033, would cost an additional $9.1 million.
Annual operating costs for the plant in the first phase are estimated at $546,000.
In the second phase, it is estimated to have an annual operating cost of $587,300. In the final phase, the plant's annual operating cost is estimated at $717,800.
