Just in time for Santa Barbara’s first day of school on Monday, Caltrans opened the Castillo Street passageway underneath Highway 101 on Friday afternoon. For many City College students, the underpass is an essential way to get to campus, as it is for downtown employees and grade-school students coming the other direction from beachside apartments and southbound 101. Falling below sea level, the underpass’s long-standing water seepage problems have been remedied this time with a geothermal membrane, which directs underground water to a drain, overlaid with a concrete slab. The road was completed, striped, and opened at a cost of $1.5 million.