If any work or undertaking for which a permit has been issued is not
commenced within a reasonable time, not to exceed 90 days from the date of the
issuance of the permit, or if after the commencement of such work or undertaking
the same is discontinued for 1 year, or less, and there appears to be no
reasonable grounds for delay, said permit shall automatically become void and of
no effect beyond that which has been lawfully performed or
accomplished.