ARDEN HILLS — Development of the Twin Cities Army Ammunition Plant site has reached a critical juncture.

Planners are preparing for the next phase of work at the sprawling Arden Hills site. A state bonding bill includes $30 million for road work necessary to propel development of the property. Ramsey County Board Chairman Jim McDonough said the roads will support up to 1,700 housing units and 4,000 jobs.

Ramsey County bought the 427-acre property for $28 million in 2012. Employment at the small arms ammunition plant was at its peak in 1943 when about 26,000 people worked there. More than half were women.