McCook Main Tunnel System, CUP Underflow Plan

McCook Main Tunnel System, CUP Underflow Plan

Project Description

The McCook Reservoir is a key component of Chicago’s Tunnel and Reservoir Plan (TARP), providing approximately 10 billion gallons of additional CSO storage to the MWRDGC network.  The Main Tunnel System (MTS) will connect the Mainstream Tunnel to the Reservoir and will consist of a 1,600 foot long, 33-foot inside diameter (ID) tunnel extending from the Mainstream Tunnel to the McCook Reservoir at a depth of approximately 300 feet.  GSG was retained to conduct safety evaluation surveys on an ongoing basis during construction.


GSG’s safety evaluations included a review ongoing construction activities and reviews of the safety record-keeping. Our field inspections included observation and document of material handling, crane usage for lifting man cage/ equipment, tunnel excavation, construction shaft excavation and maintenance activities. The records review included assessment of safety training records, air monitoring, safety inspection records, safety training presentations, accident/incident records and follow-ups in addition to job hazard analysis documents, and safety meeting records.

Related Projects

Join our newsletter

Please register for our newsletter to receive information about GSG.

join now

Follow us on:

Contact Us

Chicago HQ
  • 2942 W. VanBuren, Chicago, IL 60612
  • (312) 733.6262
  • (312) 733.5612

Contact us


* indicates required