a) The owner of a lagoon must increase the total amount of surety in place so as to equal the level of surety as calculated within 90 days after:

1. 1) a modification resulting in an increase in the volume of the lagoon; or
2. 2) an increase in the cost factor under Section 900.703(b) of this Part.

b) If modification of a lagoon results in a decrease in volumetric capacity, the owner or operator may provide the Department with documentation of the reduction in volumetric capacity and request a recalculation of the level of surety. Within 90 days after a request by the owner or operator under this subsection (b), the Department must either:

1. 1) release any surety amount above the level of surety as recalculated based upon the owner's documentation of reduction of volumetric capacity; or
2. 2) conduct an inspection and determine the amount by which volumetric capacity has been decreased.