Rachel Carson, a driving force behind the modern environmental movement, grew up in a modest homestead in Springdale Borough near the Allegheny River. For the budding marine biologist, the river's waters were an early inspiration. Now, more than four decades after Ms. Carson's death, her presence may return to those waters. Allegheny County Council tomorrow will consider renaming the Ninth Street Bridge in her honor. If the resolution is approved, Ms. Carson would join Roberto Clemente and Andy Warhol as namesakes for the three Downtown "Sister Bridges" that cross the Allegheny. "This is long overdue," said Esther L. Barazzone, president...