American Underground-Construction Association's Featured Project

Industry News

Each month AUA will feature an outstanding Underground Project currently under construction, featuring its unique aspects in terms of technology, location, function, etc. Contact AUA to nominate projects.

This month's Featured Underground:

TARP - TORRENCE AVENUE TUNNEL

Chicago, Illinois

 

The Tunnel and Reservoir Plan (TARP), commonly known as the Deep Tunnel Project, is the daring and unique concept developed by the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) as a two-phase solution to the problem of waterway pollution and basement flooding due to sewer system backups created by the combined sewer overflows (CSOs).

Phase I, primarily for pollution control, includes the tunnels, shafts, connecting sewers and structures. These Phase I facilities intercept, during wet weather events, the CSOs within the MWRDGC TARP service area. The tunnels and shafts provide temporary storage of the CSOs for subsequent treatment at Water Reclamation Plants (WRP) before discharging into waterways. Ultimately, upon completion of Phase II, the tunnels, located from 150 ft to 330 ft below ground, will convey the CSOs to reservoirs for storage until WRP capacity is available.

Phase II, which includes the reservoirs, pumping facilities, additional tunnels and shafts, has been planned to serve a dual purpose. The reservoirs provide storage of excess flows during wet weather events, those beyond the WRP capacity. Following the wet weather events, the stored flows can be conveyed, at controlled rates, to the WRPs for full treatment. These excess flows previously would have resulted in both overflows into the waterways and eventually backups in the local sewer systems. The storage capacity of the reservoirs also will promote the full utilization of the conveyance capacity of the tunnels and shafts, which in turn results in optimizing the conveyance capacity of the existing sewer systems. Therefore pollution control is further enhanced by allowing for capture of a greater volume of CSOs and greatly minimizing backups in the local sewer systems.

The TARP project consists of four systems: O'Hare, Mainstream, Des Plaines, and Calumet, covering a total area of 375 mi² and serving the City of Chicago and 51 neighboring communities.

With only one contract left before completion of the Phase I tunnels, the 7.7 mi Little Calumet leg, part of the Calumet System, the pollution control phase of the project is now 86 % complete.

 

System

Length

(mi)

Completed

(mi)

Operational

(mi)

Mainstream

40.5

40.5

31.2

Calumet

36.5

20.7*

20.7

O'Hare

6.6

6.6

6.6

Des Plaines

25.6

25.6

16.9

TOTAL

109.2

93.4

75.4

Note: * The Torrence Avenue Tunnel Project of the Calumet System is currently under construction.

Table 1. TARP Phase I Status

 

CALUMET TUNNEL SYSTEM

TORRENCE AVENUE LEG

Tunnel, Shafts and Connecting Structures

Owner: The Metropolitan Water Reclamation District of Greater Chicago

Bid Date: March 18, 1998

Project:

Tunnel Work

  • 33,862 LF of 25-foot inside diameter lined rock tunnel
  • 8,184 LF of 15-foot inside diameter lined rock tunnel
  • 523 LF of 96" inside diameter jacked in place tunnel
  • 200 LF of 72" inside diameter jacked in place tunnel
  • 392 LF of 60" inside diameter jacked in place tunnel
  • 65 LF of 48" inside diameter jacked in place tunnel
  • 131 LF of hand mined soft ground tunnels ranging in size 12" to 120" in finish diameter

Shaft Work

  • 1 ea of 25-foot finish diameter Construction Shaft
  • 1 ea of 33.5-foot finish diameter Control Gate Shaft
  • 9 ea of lined Drop Shafts (7 to 25 feet finish diameter)

Surface Work

  • 2 ea of Sluice Gate Structures
  • 11 ea of Backflow Gate, Interceptor and Connecting Structures
  • 2 ea of Existing Pump Station Connections
  • Miscellaneous Connecting Sewers

Bid Price: $140,666,650

OWNER/OPERATOR:

Metropolitan Water Reclamation District of Greater Chicago

DESIGNER:

Harza Engineering Company

CONTRACTOR:

Kenny (Sponsor) / Kiewit / Shea, Joint Venture

PROJECT LOCATION:

Southeast side of Chicago, along the Calumet River from approximately 91st Street to 138th Street

PROJECT SCOPE:

8.1 miles of 25 foot and 15 foot diameter concrete-lined tunnel in rock from 270 to 310 feet deep; 8 dropshafts from 7'- 2" to 25' diameter; one 25' diameter construction shaft; one 31' diameter wheelgate shaft; one access shaft. Total storage volume of 143 million gallons

AREA SERVED:

21.8 square mile area within the City of Chicago

POPULATION SERVED:

176,000

TUNNEL SYSTEM:

The Torrence Avenue Leg tunnel is part of the 36.5 mile long Calumet TARP System serving the southeast side of Chicago and 13 neighboring suburbs

CONSTRUCTION COST:

$140.7 million

FUNDING:

MWRDGC Bond Fund, and low interest loans from the State Revolving Loan Fund, a federal grant-capitalized water pollution control fund

DATES:

Contract award: April, 1998

Scheduled completion: November, 2002

PRIMARY BENEFITS:

Pollution and flood control: Prevents raw sewage mixed with rainwater from spilling into Lake Michigan and the Calumet River. Eliminates an annual average of 2.1 million pounds of biochemical oxygen demand (BOD) pollution in combined sewer overflows, including overflows from two major pump stations (87.5% reduction). Helps prevent pollution of Lake Michigan from river reversals. Provides capture and delivery of excess combined sewage from the service area to the Thornton CUP Reservoir, which will afford major flood control benefits as well as additional pollution control.

 

 

GEOLOGY OF THE TORRENCE AVENUE LEG

 

The host rock for the tunnels is the Silurian dolomite which constitutes the bedrock throughout the area. The tunnels are approximately 310 feet below existing grade elevation. The top of rock projects about 80 to 100 feet below ground surface. Glacial drift and lake bed deposits overlay the bedrock. The dolomite strata dip at a low angle in an easterly direction. Glacial erosion has truncated the top of rock with the result that the total thickness of the dolomite diminishes from East to West. A reef mass centered just South of 106th Street along the Torrence Avenue Leg consists of poorer quality rock.

The dolomite has very good tunneling properties. It is slightly argillaceous, homogeneous and strong. The unconfined compressive strength varies between 14,000 psi and 18,000 psi. Bedding planes are generally not very pronounced. Two orthogonal joint systems, a Northeast and a Northwest set, prevail but the joints are widely spaced. In the exploratory borings, which were spaced about 2,000 feet apart along the tunnel alignment, the mean RQD values varied between 91 and 98, showing excellent rock quality. The underground openings are generally self-supporting. Groundwater inflow is mainly through joints/faults and bedding planes. Inflow rate is quite variable. Occasional shear zones can contribute inflows in the order of 100 gpm over 100 feet of tunnel.

27 FT - 4 IN TBM SPECIFICATIONS

Model 740-11-1

Machine Diameter

27 ft - 4 in

Cutters:

Diameter

17 inch

Number 48
Nominal Capacity 55,000 lbs

Cutterhead Bearing

Two Row Tapered

Machine Thrust:

Number Cylinders

4

Boring Stroke

7.5 ft

Cutterhead Thrust

2,640,000 lbs

Shield Drag

800,000 lbs

Nominal Thrust

3,440,000 lbs

Pressure at Nominal Thrust

2,800 psi

Advance Rate:

Maximum Rate

26 ft/hour

Maximum Penetration

0.9 inch/rev

Cutterhead Drive:

Type

Electric

Power

3000 hp (10 @ 300hp)

Speed

5.4 rpm

Torque

2,900,000 lb-ft

Conveyor:

Drive

Hydraulic

Width

42 inch

Speed

370 ft/minute

Capacity

2,200 tons / hr

Hydraulic System:

Thrust Circuit

150 hp, 4500 psi max

Gripper / Auxiliary Circuits

75 hp, 4000 psi max

Conveyor / Fast Retract

(2) 75 hp, 1000 psi max

Electrical System:

TBM Motor Circuits

575V, 3 Phase, 60 Hz

Auxiliary Equipment

480V, 3 Phase, 60 Hz

Controls and Lighting

120V, 1 Phase, 60 Hz

Primary Voltage

13,200V

Transformers

(2) 2500kVA, 575V

(1) 500 kVA, 480V

CONSTRUCTION OF THE TORRENCE AVENUE LEG

 

The South Heading of the mainline tunnel (2,700') was mined between May 14, 1999 and June 17, 1999 on a two-shift basis operation. The 27'-4" f refurbished Robbins TBM has been backed out, partially disassembled, turned, reassembled and walked to the gripper area to start the 33,000' of mainline mining to the North. North Heading started on August 6, 1999, and after mining 330' of tunnel with a temporary conveyor system, the permanent total conveyor system was installed. The long drive for the North Heading started on August 17, 1999, with 2,147' mined as of August 27, 1999. The best 8-hour shift and 24-hour productions to date are 108 feet and 270 feet respectively.

The TBM erection chamber for the first of the two 17'-10" f (4,000' each) connecting spurs is complete with excavation for the second underway. The erection of the refurbished 17'-10" f Robbins TBM should start in September with a October kick-off for the first run.

Additional overburden shaft work at the ten Drop Shaft sites is ongoing with downhole drilling complete at one of the sites. Additional overburden work for the first of three overburden spur tunnel drives is nearly complete. The first of three Lovat TBMs should get underway in late summer or early fall.

The following staff members are currently on the project: Ted Budd, Vice-President and Project Manager; Bob Rautenberg, Assistant Project Manager and Project Engineer; Paul McDermott, Assistant Project Engineer; Mike Bosshart, Mark Saylor and Luminita Calin as Staff Engineers; Al Redmon, General Superintendent; Jesse Rhynes, Shaft Superintendent; Dan Martz, future 15' Tunnel Superintendent; Joe Gallik, Equipment Superintendent.

Many thanks to Ted Budd, Vice President and Luminita Calin, Project Engineer, Kenny Construction, for providing the TARP information.

 

 


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