The city of Chattanooga is planning a $5.25 million solar farm designed to provide power for the Moccasin Bend Sewage Treatment Plant.
Officials said about half of the city's power bill is for the huge treatment plant, and said the solar plant would save the city about $200,000 per year. The project would pay for itself in 20 years, it was stated.
The city will have to fill 2.73 acres of wetlands for the project on the treatment plant site so it will be required to purchase wetland mitigation credits for twice that area from Sequatchie Valley Wetland Mitigation Bank. A wetlands mitigation fee of $247,500 will be paid to Southeastern Green Works LLC..
City officials said, "The city of Chattanooga is authorized to install a photovoltaic solar facility onsite at the Moccasin Bend Waste Water Treatment Plant (MBWWTP) to provide supplemental power. The project site is approximately 10 acres. Approximately 7.182 acres of wetlands exists onsite; 2.73 acres are will to be permanently impacted. Permanent impacts include clearing and grubbing of vegetation and placement of fill material to accommodate the solar array. The purpose of this project is to construct a solar array to provide renewable solar power to the wastewater treatment plant. The primary goal of the solar project is to lower annual energy costs and shield the end users from rising energy costs.
"The applicant submitted an analysis of potentially practicable alternatives to the activity. The overall purpose of the activity is to construct a solar array on 10 acres of land constructed with a fixed axis racking system with approximately 9,360 south facing 340-watt panels for a total array size of 3.18MW. The activity is projected to reduce the WWTP’s power usage and reduce its dependency on the Electric Power Board.
"Relying on the electrical grid is more expensive than the Preferred Action Alternative and increases potential exposure to the rising cost of power.
"The applicant is required to mitigation for wetland impacts through the purchase of a minimum of 5.5 wetland credits from Sequatchie Valley Wetland Mitigation Bank to mitigate for unavoidable impacts to 2.73 acres of PFO wetlands. The impacts are within the primary service area of the identified bank, but not in-system. Division rules require wetland mitigation should not be less than a 2:1 ratio.
"The MBWWTP is the regional wastewater treatment facility for the city of Chattanooga, Hamilton
County and parts of northern Georgia. The MBWWTP is one of the city of Chattanooga’s most
valuable assets and treats up to 230 million gallons of wastewater per day. The MBWWTP is the
largest user of power among the city facilities, accounting for approximately one half of the city’s
power costs. The city is constantly looking for ways to reduce this power usage and reduce its
dependency on the Electric Power Board (EPB), the Tennessee Valley Authority (TVA), and the
MBWWTP Renewable Energy Project is one example of these efforts. The project would attempt
to fill a public need for wastewater treatment provided at an affordable rate. It is estimated that the
proposed 10-acre solar farm would produce approximately 3.18 megawatts of power with a year 1
annual output of approximately 4,400,000 kilowatt per hour (kWh) of renewable power output.
This estimate is based on a conceptual design of 9,360 panels rated at 340-watts. The Preferred
Action Alternative would offset approximately 8-9% of the annual energy demand at the
MBWWTP. The applicant included the MBWWTP Solar Feasibility Analysis report, which stated
the average annual kWh power cost over the last five years has averaged $0.075 per kWh; the solar offset is expected to be approximately $0.05 per kWh.
"The project would create approximately 10 temporary jobs throughout construction and one
permanent job for operations and maintenance. The estimated total wage benefit for temporary
positions is $107,900. The estimated total wage benefit for permanent positions is $158,620.
"The MBWWTP’s solar farm would include approximately 10,000 panels and is budgeted to cost
approximately $5.25 million, including site work. The city’s Public Works Department, which
operates the MBWWTP, expects the Project to save $200,000 a year, taking about 20 years to pay
off economically. The Preferred Action Alternative would result in financial benefits to end users
of the MBWWTP. The primary goal of the proposed solar farm is to lower annual energy costs and
shield the end users from rising energy costs associated with MBWWTP operations. A solar project
would allow the renewable solar energy production to help stabilize rising energy rates. The
Preferred Action Alternative would offset approximately 8-9% of the annual energy demand at the
MBWWTP.
"The development of a renewable energy Project would incentivize forward thinking,one half the city’s power cost. By maintaining the capacity for facility expansion, the Project would
support future development that would increase demands on wastewater treatment services. In
addition, the Chattanooga city government has enacted a series of bold sustainability policies, and
implementation of this Project supports those policies which would contribute to attracting
additional environmentally conscious businesses to consider locating within or near the city of Chattanooga.
"The MBWWTP is the largest user of power among the city facilities, accounting for approximately one half the city’s power cost. By maintaining the capacity for facility expansion, the Project would
support future development that would increase demands on wastewater treatment services. In
addition, the Chattanooga city government has enacted a series of bold sustainability policies, and
implementation of this Project supports those policies which would contribute to attracting
additional environmentally conscious businesses to the city of Chattanooga.
"This project will be used for educational outreach. Local and regional school groups can visit the
facility for educational experiences about wastewater treatment process. As a gold-certified
National Biosolids Partnership facility, the MBWWTP offers educational tour and children’s
programs to increase knowledge of its biosolids program. It is estimated that the three school
groups with 20 students may tour the MBWWTP, including the solar array, on an annual basis."