An operator who registers with the division two or more mine sites may elect, at the time the second or a subsequent site is registered, to post a single bond in lieu of separate bonds on each site. A single bond so posted shall be in an amount equal to the estimated cost of reclaiming all sites the operator has registered, determined as provided in section 208.23 . The penalty of a single bond on two or more mine sites may be increased or decreased from time to time in accordance with sections 208.14 , 208.15 , and 208.19 . When an operator elects to post a single bond in lieu of separate bonds previously posted on individual sites, the separate bonds shall not be released until the new bond has been accepted by the division. [C71, 73, 75, 77, 79, 81, §83A.24 ] 85 Acts, ch 137, §19 C93, §208.24 96 Acts, ch 1043, §16 Referred to in §208.14