The Planning Board shall approve a site plan or subdivision only if the plan as proposed or conditioned adequately specifies how historic sites and archaeological sites on the parcel are to be treated and such proposal is appropriate given the nature of such sites. The applicant shall monitor construction to assure that all provisions of the approved plan as to the identification, preservation, or removal of historic features and historic or archaeological artifacts are complied with and shall appoint an individual in the field with the responsibility therefor and retain a person with the necessary expertise in connection therewith. In the case of accidental finds, the applicant shall report the same forthwith to the Zoning Officer/Administrative Officer and cease all construction activity with respect thereto for two working days (Monday through Friday, excluding holidays). The Commission or, in the absence of a quorum, the Chairman or, in his absence, the Secretary, may within such time order that the artifacts discovered be documented and removed under the supervision of the expert identified in the approval and at the expense of the applicant. In the case of extraordinary finds, the Commission, Chairman, or Secretary, as the case may be, may order that the work cease and that the plans be modified to reflect the find. Such order shall remain in effect only until the next meeting of the Planning Board unless the Planning Board at such meeting continues the order, with or without modifications.