DLZ’s design of Columbus’ $368-million, 20-ft-dia, 170-ft-deep tunnel project was completed recently. It’s the biggest capital project ever for Columbus.
“The OSIS Augmentation and Relief Sewer (OARS) was originally conceived as a shallow sewer, but since it had to go through downtown, it seemed more feasible to make it a tunnel. It acts both for equalization and conveys the flow down to the treatment plant. In a normal year, OARS alone will save about 2 billion gallons of combined sewer overflow from going into the Olentangy River,” Coffey says.
Firm in Focus
6121 Huntley Rd. Columbus, Ohio
CEO: Vikram “Raj” Rajadhyaksha
Lower Olentangy Tunnel: The relief sewer project ends in the arena district. DLZ is already designing LOT, a three-mile-long combined sewer project to connect downtown and Ohio State University.