Section 15-103. Qualifications of force of department

a. To qualify for
  membership in the department a person shall be:
    1. A citizen of the United States.
    2. Able understandingly to read and write the English language.
    3. Shall have passed his or her eighteenth birthday but not his or her
  twenty-ninth  birthday  on  the  date  of  the  filing  of  his  or  her
  application for civil service examination. No person who qualifies under
  this requirement shall be disqualified from membership in the department
  because  of having passed his or her twenty-ninth birthday subsequent to
  the filing of his  or  her  application.  However  no  person  shall  be
  appointed  unless  he or she shall have attained his or her twenty-first
  birthday.
    b. A  conviction  of  a  felony  shall  disqualify  all  persons  from
  membership in the department.
    c.  Nothing  in  this  section  is intended to repeal or supersede the
  provisions of section 12-138 of the code.