A use legally established pursuant to a Specific Use Permit prior to the date of adoption of these Zoning Regulations shall be deemed a pre-existing conditional use and shall be permitted to continue, provided that it is operated and maintained in accord with any conditions prescribed at the time of its establishment.

Alteration or expansion of a pre-existing specific use shall be permitted only upon the granting of a Conditional Use Permit as prescribed in these regulations, provided that alterations not exceeding $2,500 in value as determined by the Director of Planning and Building, shall be without the granting of a Conditional Use Permit.

A Conditional Use Permit shall be required for the construction of a structure housing a pre-existing use if the structure is destroyed by fire or other calamity, but specific act of God or by the public enemy to an extent greater than fifty percent (50%). The extent of damage or partial destruction shall be based upon the ratio of the estimated cost of restoring the structure to its condition prior to such damage or partial destruction to the estimated cost of duplicating the entire structure as it existed prior thereto. Estimates for this purpose shall be made by or shall be reviewed and approved by the Director of Planning and Building and shall be based on the minimum cost of construction in compliance with the Building Code.