Trotter and Associates determined that the City of St. Charles may be eligible for an IEPA low interest loan with a reduced interest rate for the 2017 Phosphorus Remoal and Digester Improvement since the project will provide to nutrient removal and energy efficiency.
The City of St. Charles and TAI demonstrated that more than 50% of the construction cost is associated with nutrient removal and incorporating sustainable energy practices into the project. St. Charles will be implementing the A2/O biological process. The project will also switch the anaerobic digestion heating system from using natural gas to biogas by installing new biogas storage, conditioning equipment and combination boiler/heat exchangers. This heating system will heat the Digesters and provide heat to the Anaerobic Digester Control Building.
By reducing the interest rate from 1.76% to 1.56%, it saves the City over $25,000 in construction period interest alone. However, if this interest rate is applied over the life of the loan, the savings become substantially more. Using the 1.76% interest rate for the loan repayments, the City would pay a total $18,636,410 between 2019 and 2038. With a 1.56% interest rate, the City would make repayments over the same period totaling $18,251,917. Therefore over the life of the loan, the City of St. Charles will save approximately $384,000.