(a) Except as provided in subsection (b) of this section, before the Department exercises its authority under § 4-208 or § 4-209 of this subtitle, the Department shall:

(1) Notify the county or municipality of the violation and the Department’s intended action; and

(2) Conduct a joint inspection with a representative of the county or municipality.

(b) If the Department determines that there is a substantial threat to the environment, the Department may take appropriate enforcement action without first conducting a joint inspection under subsection (a)(2) of this section.