Within 21 days after receipt of the tentative parcel map the tentative parcel map shall be certified or approved. The 21-day time period shall commence following the certification of an environmental impact report, the adoption of a negative declaration, or a determination that the project is exempt from the requirements of Division 13 (commencing with Section 21000) of the Public Resources Code. (Ord. 3153 § 2 (Exh. C), 2010).