EAST PROVIDENCE – In the steel shell of a former dormitory and, more recently, nursing home, water collects in buckets as construction crews hammer and drill, saw and weld, and heavy machinery works to cover a series of underground water retention systems, consisting of huge pipes. Next door, the masonry elevator shaft rises three stories above construction crews working on the first floor below. The two buildings are becoming 95 units of income-restricted housing, built by One Neighborhood Builders, in a partnership with Family Service of Rhode Island, Crossroads Rhode Island and Foster Forward.