(a) the amount determined in accordance with the rules adopted by the department, which must be no less than the economic value that a delay in compliance after July 1, 1979, may have for the owner of the source, including the quarterly equivalent of the capital costs of compliance and debt service over a normal amortization period not to exceed 10 years, operation and maintenance costs foregone as a result of noncompliance, and any additional economic value that the delay may have for the owner or operator of such source; minus
(b) the amount of any expenditure made by the owner or operator of that source during the quarter for the purpose of bringing that source into and maintaining compliance with the requirement, to the extent that the expenditures have not been taken into account in the calculation of the penalty under subsection (1)(a).
(2) To the extent that any expenditure under subsection (1)(b) made during any quarter is not subtracted for the quarter from the costs under subsection (1)(a), the expenditure may be subtracted for any subsequent quarter from the costs. In no event may the amount paid be less than the quarterly payment minus the amount attributed to actual cost of construction.
(3) If the owner or operator of any stationary source to whom notice is issued under 75-2-425 does not submit a timely petition under 75-2-425(2)(b) or submits a petition that is denied and if the owner or operator fails to submit a calculation of the penalty assessment, a schedule for payment, and the information necessary for independent verification thereof, the department may enter into a contract with any person who has no financial interest in the matter to assist in determining the amount of the penalty assessment or payment schedule with respect to the source. The cost of carrying out the contract may be added to the penalty to be assessed against the owner or operator of the source.
(4) Any person who fails to pay the amount of any penalty with respect to any source under 75-2-421 through 75-2-429 on a timely basis shall pay in addition a quarterly nonpayment penalty for each quarter during which the failure to pay persists. The nonpayment penalty is equal to 20% of the aggregate amount of the person's penalties and nonpayment penalties with respect to the source that are unpaid as of the beginning of the quarter.