Senior Housing Step Taken: The City Council has paved the way for possible construction of low-cost senior housing on a 25,000-square-foot site near City Hall. In a 4-0 vote this week, the council agreed to rezone the parcel at 310 Broadway to accommodate several new office suites, an underground parking complex, 15 new apartments and an existing bank building. Under the plan, First American Bank and Trust Co., which owns the site, would reserve the 15 one-bedroom and studio apartments for low-income, elderly residents and would charge rents of $400 to $600 a month. The zone changes will come before the council for a second reading and final vote July 9. If approved, the changes will become effective 30 days later.