(1) The following classes of modifications to approved sites shall require that an owner or operator amend the approved design or ground water monitoring program:
(a)  Lateral expansion outside the approved waste management unit boundary design;
(b)  Unpredictable change affecting any environmental monitoring program;
(c)  Change of liner design; or
(d)  A modification of the design or operation due to initiation of corrective action and remediation.
(2)  The scope of new investigations and plan amendment shall be defined by the owner, director and health district before any modification to the decision is begun. Only those stages of the applicable approval process affected by the request for modification shall be required.