James Belew, Black & Veatch, Water Global Communications

The U.S. Army Corps of Engineers (USACE) has selected Black & Veatch as design engineer for the McCook Reservoir Main Tunnel as element of Chicago's massive Tunnel And Reservoir Plan or TARP system. The tunnel will connect the TARP's Mainstream Tunnel to the planned McCook Reservoir in aims to bolster protection of the local water supply.

Designed to improve water quality in area rivers and Lake Michigan and reduce flood risk for the city of Chicago and suburban communities, the TARP project, implemented by the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC), collects and diverts combined sewer overflows and floodwaters throughout metropolitan Chicago to temporary holding reservoirs before treatment.

The new tunnel will connect sections of TARP to the McCook Reservoir currently under excavation

"We are pleased that Black & Veatch has engaged its top resources to execute this assignment," said Linda Sorn, USACE Chicago District Chief of Technical Services. "The McCook Reservoir is a marquee project for the USACE and our local sponsor, the Metropolitan Water Reclamation District of Greater Chicago, to reduce flood risk, protect the vital Lake Michigan water supply and improve the quality of water in area watercourses."

In addition to the main gates and connection tunnel system for McCook Reservoir, Black & Veatch is also leading the design for the groundwater protection system, the Thorn Creek connection tunnel, and is leading final preparations for the Thornton Composite Reservoir. The bifurcated tunnel system will be approximately 1,800ft long and about 33ft in diameter (550m x 10m diameter). A set of six high-head wheel gates will be installed 300 feet below grade to control flows into and out of the McCook Reservoir.

Black & Veatch will prepare a geotechnical baseline report and assist in development of risk management strategies for design and constructability, in addition to sequencing and procurement of work, schedule and budget controls. Computational fluid dynamics and finite-element numerical modeling will be used to address complex system hydraulics and geotechnical conditions, including design details of steel and concrete tunnel linings.

Projected construction costs for the facilities Black & Veatch is designing in conjunction with TARP are estimated at more than $500 million.

The network of deep tunnels and related facilities that make up the ground-breaking water control system that is TARP, includes the O'Hare, Mainstream, and Des Plaines systems in the north, and the Calumet system in the south portion of Chicago's Cook County. The tunnels range in diameter from 8ft to 33ft (2.5-10m) and are connected to the surface via 250 drop shafts and operated via more than 600 flow diversion and control structures.

Construction of the system Plan started more than 30 years ago and comprises today more than 110 miles (176km) of 8ft to 33ft diameter (176km x 2.5-10m diameter) deep level tunnels. The main tunnel elements are:

The TARP masterplan of more than 100 miles of tunnels and three major storage reservoirs

The 6.6 mile (10.5km) O'Hare - Upper Des Plaines System
The 40.5 mile (65km) Mainstream System
The 25.6 mile (41km) Des Plaines System
The 36.5 mile (58.5km) Calumet Tunnel System
The 8.1 mile (13km) Torrence Avenue Leg of Calumet System and
The 7.7 mile (12.3km) Little Calumet Leg of Calumet System

These tunnels provide nearly 2.5 billions gallons of storage for CSOs and flood waters with an 85% capture rate for all CSOs. The tunnels are connected to the surface via 250 drop shafts and managed by more than 600 flow diversion and control structures. The O'Hare system with its Reservoir is built out and in service. The Mainstream and Des Plaines systems will connect to the McCook Reservoir that is in construction, and the Calumet System will connect to the future Thornton Composite Reservoir.

Most of the tunnels were driven through the Silurian age dolomite of the Chicago region using hard rock main beam TBMs of 8ft to 33ft (2.5-10m) diameter and lined with in-situ concrete. Robbins TBMs that worked on the project broke many world records of advance and it was on the TARP that major advances of TBM design and technology were accomplished. The record setting advance rates for a nearly 18ft diameter TBM on the Little Calumet Leg contract, for example, achieved records of 168ft (51m) of tunnel boring in a single 8hr shift, 452ft (137m) within 24hr, and 1,916ft (583m)/week and 7,008ft (2,136m)/month in 2003. These are testaments of advanced technologies and benefits of extensive know-how of the regional tunneling.

"The McCook Reservoir Main Tunnel System when complete will have a positive impact on the many people drawn to Chicago's rivers and Lake Michigan shoreline as well as aquatic life in these valuable resources," said Dan McCarthy, President and CEO of Black & Veatch's global water business.

"Experts in our core business groups of tunneling, dams, levees and reservoirs, as well as our Federal Services Division, are an integral part of the USACE and MWRDGC project team and are fully engaged in bringing this project to fruition," said Faruk Oksuz, Associate Vice President and Black & Veatch National Practice Leader for Dams, Levees and Reservoirs.

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