4. “General corporate purpose” means:
a. The acquisition, construction, reconstruction, extension, improvement, and equipping of city utilities, city enterprises, and public improvements as defined in section 384.37, other than those which are essential corporate purposes.
b. The acquisition, construction, reconstruction, enlargement, improvement, and equipping of community center houses, recreation grounds, recreation buildings, juvenile playgrounds, swimming pools, recreation centers, parks, and golf courses, and the acquisition of real estate therefor.
c. The acquisition, construction, reconstruction, enlargement, improvement, and equipping of city halls, jails, police stations, fire stations, garages, libraries, and hospitals, including buildings to be used for any combination of the foregoing purposes, and the acquisition of real estate therefor.
d. The acquisition, construction, reconstruction, and improvement of dams at the time of acquisition.
e. The removal, replacement, and planting of trees, other than those on public right-of-way.
f. The acquisition, purchase, construction, reconstruction, and improvement of greenhouses, conservatories, and horticultural centers for growing, storing, and displaying trees, shrubs, plants, and flowers.
g. The acquisition, construction, reconstruction, and improvement of airports at the time of establishment.
h. The undertaking of any project jointly or in cooperation with any other governmental body which, if undertaken by the city alone, would be for a general corporate purpose, including the joint purchase, acquisition, construction, ownership, or control of any real or personal property.
i. Any other purpose which is necessary for the operation of the city or the health and welfare of its citizens.
5. The “cost” of a project for an essential corporate purpose or general corporate purpose includes construction contracts and the cost of engineering, architectural, technical, and legal services, preliminary reports, property valuations, estimates, plans, specifications, notices, acquisition of real and personal property, consequential damages or costs, easements, rights-of-way, supervision, inspection, testing, publications, printing and sale of bonds, interest during the period or estimated period of construction and for twelve months thereafter or for twelve months after the acquisition date, and provisions for contingencies.