The general manager shall adopt rules and regulations to carry out the purposes of the civil service provisions of this division and may from time to time amend existing rules. Except as otherwise provided herein such rules shall govern applications, examinations, eligibility, duration of eligible lists; certifications of eligibles; appointments; promotions; transfers; resignations; layoffs or reductions in force, both permanent and temporary, due to lack of work or funds, retrenchment, or completion of work; the filling of positions, temporary, seasonal, and permanent; classification; and such other matters as are not in conflict with the civil service provisions of this division.