Upon the failure of the subdivider to complete any improvement, act, or obligations within the time specified, or an approved extension thereof, the City Council may, upon notice in writing of not less than ten (10) days, served upon the person responsible for the performance thereof, or upon notice in writing of not less than twenty (20) days, served by certified mail addressed to the last known address of such person, determine that the subdivider is in default and may cause the improvement security or such portion thereof as is necessary to complete the work or act or other obligation of the subdivider secured thereby to be forfeited to the City. (Ord. 527, 8-4-1997)