The storage of any gasoline or highly inflammable material in any hangar located on the airport is expressly prohibited. All paints, dopes, varnishes and solvents shall be stored and kept in accordance with appropriate fire and safety rules and regulations. No gasoline may be sold or dispensed on the city airfield, except from the city’s aboveground storage tanks through an approved stationary gasoline pump; except that, trucks may be used to deliver gasoline to aircraft parked in designated parking or unloading areas.