For the purpose of industrial cost recovery, the year shall be divided into quarterly periods, said periods to begin on the first day of July, October, January, and March, and all industrial users of the City of Mt. Vernon shall pay the cost as determined for industrial cost recovery and such payment shall be made quarterly on the fifteenth day of the month immediately following the expiration of the quarterly period for which service has been supplied, and such charge shall be payable within ten (10) days after rendition thereof, and in the event such bills are not paid within said ten (10) days, a service charge of ten percent (.10010) shall be added thereto.
(Prior Code, Art. 16, § 16.7(u))