The Metropolitan Sanitary District of Greater Chicago Tunnel and Reservoir Plan Contract Number 75–124–2H consists of tunnels and drop shafts; bid December 14, 1977 at $101,970,680 by the Joint Venture of J.F. Shea Company, Inc. and Peter Kiewit Sons Company. Major items of work are a 7.62 m (25ft) construction shaft, 4,184 m (l3,276.LF) of 9.14 m (30 ft) finished diameter rock tunnel, 1,843 m (6,048 LF) of 4 m (13 ft) finished diameter rock tunnel and 17 drop shafts, approximately 76 m (250 ft) deep with adits varying from 30 m (100 ft) to 400 m (1300 ft) in length. This project is located in downtown Chicago and particular attention will be paid to the following:

  • muck handling,

  • slurry wall,

  • Hughes Drill for drilling shafts,

  • shaft locations and problems encountered during construction, and

  • tunnel support. Contract 75–124–2H extends along the Chicago River from Roosevelt Road on the south to Ogden Avenue on the north.

In addition a branch tunnel runs east from approximately mid-project ending near Lake Michigan. The contract was bid on December 14, 1977 with three joint-ventures submitting bids. Of these the joint venture of J.F. Shea Co., Inc. Walnut, California, (Sponsor), Peter Kiewit Son's Co., Omaha, Nebraska and Shea Company and Associates, Walnut, California was low with a bid of $101,976,680~00. The MSD awarded the job to the Joint-Venture on January 5, 1978 with a scheduled completion date of January 23, 1983. The project consists of the following major items of work:

  1. a 7.62 m (25 ft) minimum diameter Construction Shaft, 67.06 m (220 ft) deep.

  2. 4183.7 m (13,726 LF) of 9.14 m (30 ft) Concrete lined tunnel in rock.

  3. 2026.3 m (6,648 LF) of 3.96 m (13 ft) Concrete lined tunnel in rock.

  4. Seventeen concrete lined Drop Shafts varying in finished diameter from 1.22m (4 ft) to 3.66 m (12 ft), and each approximately 76.2 m (250 ft) deep with chambers and connections to the tunnels varying from 30.5 m (l00 ft) to 396.2m(l,300 ft) in length.

ENGINEERING GEOLOGY

Because this project is located near downtown Chicago or the "Loop" as it is usually called, geology is somewhat a mixed bag. The first 4.57 m (15 ft) from ground level consists of loosely compacted fill and often rubble from the rebuilding operations after the Chicago Fire in 1873. The next 19.8 m (65 ft) to 30.5 m (100 ft) of common material consists of soft to hard clays with a water content varying from slightly moist to saturated. Occasionally glacial till with boulders up to 203 mm (8 in) in diameter is found beneath the overlying clays. Often an extremely dense hardpan is also encountered above rock proper. Generally, caisson supports for the buildings and structures along the route of the tunnel bear upon this hardpan material. The material encountered here is dry, hard and very dense with occasional weathered rock fragments included within. Rock generally consists of a dolomite, fine grained with some jointing and fracturing.

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