A developer wants to build six two-bedroom apartments on less than an acre near the Danbury-Bethel line, using a state law that lets more housing go up if some units are affordable. The land at Knollwood Drive and Reservoir Street is zoned for just one home. Neighbors raised concerns over blasting, drainage, and traffic, saying the area is already packed. Two units would be income-restricted, four rented at market rate. The proposal is one of several sparking debate as Bethel weighs how to manage growth while meeting affordable housing mandates.