View showing several men working in cofferdam along Allegheny River as they prepare to install Blaisdell Filter Series, No. 1. A cofferdam is a temporary structure created to expose areas that are normally underwater so that work, such as creating supports or repairs can be completed.
Pittsburgh City Photographer Collection, 1901-2002, AIS.1971.05, Archives Service Center, University of Pittsburgh
Waterworks--Pennsylvania--Pittsburgh--Design and construction.; Cofferdams--Pennsylvania--Pittsburgh.; Blue collar workers--Pennsylvania--Pittsburgh.; Allegheny River (Pa. and N.Y.).; Rivers--Pennsylvania--Pittsburgh.; Lincoln-Lemington-Belmar (Pittsburgh, Pa.).
Public Domain - Anybody may use this photo for any purpose