In Austin, Texas water is everything. At Waller Creek along the eastern edge of the city’s downtown, tunnel construction is underway to manage stormwater. Moving outward, Water Treatment Plant 4 (WTP4) will increase drinking water capacity for the growing city. Both of these projects are scheduled for operations in 2014.

Two other projects due to wrap up this summer are the Downtown wastewater tunnel project and the I-35 Water/Wastewater program. Both are wrapping up this summer

Looking outside of one specific city, there is talk of potential projects.

Austin
The WTP4 tunneling is divided into two projects, with separate design and construction contracts for each. Obayashi USA, in a joint venture with Manson Construction Company, is excavating two tunnels for the raw water system of the facility, including the intake on Lake Travis. MWH Constructors is the construction manager at risk and Aecom, with subcontractor Brierley Associates, is doing the design.

Excavations on the 7ft (2.1m) diameter raw water transmission main completed earlier this year. A total length of 3,873ft (1,180m) connects the pump station to the treatment plant.

Manson is constructing the intake on the lake, from which the 4,386ft (1,337m)-long intake tunnel of 9ft diameter will bring water to the pump station. This tunnel alignment is spear-headed by the two most challenging aspects of the project: the intake, and the 450ft (137m) deep access shaft with a 25.5ft (7.8m) finished diameter.

The other portion for WTP4 is the Jollyville transmission main. This 34,565ft (10.5km) tunnel will carry treated water from the plant to the Jollyville reservoir. Southland is the contactor in a joint venture with Mole, and Black & Veatch is the designer. The completed tunnel diameter is 84in (2.1m) and three TBMs of roughly 10ft (3.1m) diameter have been sourced for the excavations. The contract includes four shafts along the alignment, of which three are completed.

Southland has two of the TBMs built, one of which was refurbished by Robbins. The third is a new Robbins main beam machine. The first TBM completed its drive at the end of June, said John Arciszewski, project manager with Southland. Once the machine had hit its stride production averages were 50ft a shift (with two, 12-hour shifts each day).

When TTNA spoke with Arciszewski, Southland had just received the final pieces for the refurbished main beam machine from Robbins’ Ohio production facility. It is expected to launch in early August for the most substantial drive of the project, roughly 20,000ft (6,096m). The third machine is expected to launch in mid to late August.

Elsewhere
Outside of Austin the region is seeing smaller projects. There are long-term plans set in place, for example, in the Dallas-Fort Worth area.

The Tarrant Regional Water District (TRWD) and the City of Dallas are working in partnership on the Integrated Pipeline Project to increase water supply to the Dallas-Fort Worth region.

This 150-mile (241km) pipeline will have diameters between 84in and 108in (2.1m to 2.7m) running from Lake Palestine eastwards to Lake Benbrook.

There will be approximately 5 miles (8km) of tunnelling required for the project, for a pipeline of 120in (3m) diameter, between 50 to 100ft (15 to 30m) underground, according to Kathy Berek, spokesperson for TRWD. The tunnel is required in the last section of the pipeline project, and she estimates construction is unlikely to start until 2025.

Currently, 13 deep bores are being undertaken as part of the preliminary design. The Colorado Department of Transportation (CDOT) is working toward an expansion of its Twin Tunnels on Interstate 70 (I-70), which is Colorado’s only eastwest Interstate, providing a link over the Continental Divide.

With an estimated price tag of USD 60M, the proposed project would widen the instate to three eastbound lanes between Idaho Springs and the base of Floyd Hill, enlarging the eastbound bore of the tunnels.

The project area is 2.5-miles long, though the tunnel does not run the full portion of the project area. A USD 1M survey and geotechnical investigation started this summer. Consultant on the project is CH2M Hill.