#PROJECTS: Big Creek Storage Tunnel (BCT)

The Big Creek Tunnel (BCT) project is part of Project Clean Lake, a $3 billion, 24-year program the Northeast Ohio Regional Sewer District began in 2011 to meet Clean Water Act standards. BCT is our last of seven large-diameter combined sewer overflow (CSO) storage tunnel that, along with other projects, will reduce 4.5 billion gallons of CSO released into Lake Erie and other local waterways in the Greater Cleveland area.

The BCT includes more than four miles of 20-foot diameter tunnel, built in rock, 50 to 100 feet beneath Cleveland, Linndale, and Brooklyn. The tunnel system will capture and store a combination of sanitary sewage and stormwater from 11 CSO outfalls. BCT will reduce combined sewer overflows to Big Creek and its tributaries by 550 million gallons a year.

Project schedule

Design began in 2024 and finished in early 2026. Construction is currently expected to begin in late 2026 and continue into 2031.

Cost and bidding

Our engineers’ estimate is $295 million. Sign up to receive notifications when we post projects for bidding: procurement.opengov.com

Length and sizes

The Big Creek Storage Tunnel (BCT) will be 22,440 feet long and 20 feet in diameter.

Benefits

The project will reduce CSO volumes discharged into Big Creek and its tributaries by over 550 million gallons annually and decrease flooding.

Fact sheet

A printable set of fact sheets about the Big Creek Tunnel project are available for download. Updated March 4, 2026.