Upon receipt of a complete site plan application, the official shall refer the application to the Planning Board. The Planning Board shall review the site plan application, and within 30 days of receipt, the Planning Board may schedule a public hearing to receive comments on the application. The Planning Board shall either approve, approve with conditions or disapprove the application within 45 days after such hearing. If there is no public hearing held, the Planning Board shall either approve, approve with conditions or disapprove the application within 45 days of receipt of a complete application. The time within which the Planning Board must render its decision may be extended by mutual consent of the applicant and the Planning Board. Failure of the Planning Board to render a decision within the prescribed time limits shall constitute approval by the Planning Board.