A Danbury developer has cleared an environmental hurdle to build a seven-story senior apartment complex next to the First Congregational Church on Deer Hill Avenue. The city’s wetlands commission approved the plan after assurances that the 30-unit project would not worsen flooding near Blind Brook. The developer who bought the church, plans to lease the sanctuary back to the congregation and use apartment revenue to maintain the historic building. The entire project now awaits final planning review.