If the streets within a development are private the individuals within the development own the streets, usually as part of the home owners association. Home owners associations usually hire a private contractor to plow and maintain the streets. The city does not plow or maintain private streets. When private streets need to be maintained or replaced it is the responsibility of the home owners or the home owners association to do that. Ask your association how it will plan to pay for these future expenditures.
For further information on private streets or streets in general, contact Engineering at 651-714-3593.