Williamtown Wastewater Transfer Scheme

Project Overview

UEA completed a 150-metre sewer upgrade for Bolte Civil as a part of the Hunter Water Williamtown Wastewater Transfer Scheme (WWTS). The project consisted of three road crossings, including a 110 metre crossing of the Pacific Highway and adjacent wetlands.

Location

Tomago and Raymond Terrace NSW

Geology

Sand and marine mud

Client

Bolte Civil on behalf of Hunter Water

Length

190 metres

Pipe

3 x 600mm MS envelopers for 450mm PE

Technique

GBM & thrust boring

SCOPE OF WORKS

UEA used pilot tube microtunneling methods, combined with traditional auger boring, to provide a flexible solution to cross both major road ways and a creek whilst working in environmentally sensitive zones with a very high water table.

The first two drives, both 40 meters in length, were driven across local roads using a GBM laser pilot system, followed by a traditional auger borer. This method of pilot tube microtunneling ensured accuracy of line and level and the auger borer provided a simple and efficient method of inserting the 600mm steel enveloper pipe. The 450mm PE carrier pipe was then inserted and grouted into position.

The third drive of 110 meters was also completed using pilot tube microtunneling, ensuring accurate line and level for the enveloper pipe. The 600mm steel enveloper pipe was installed using a combination of auger boring under the Pacific Highway, and then switching to a Grundoram® hammer to ensure safe passage beneath the environmentally sensitive wetlands and a flowing creek with no surface disturbance. With less than 600mm of cover, the enveloper was successfully installed and the 450mm PE carrier pipe inserted and grouted into position.

CHALLENGES & COMPLETION

Although the location of the under bores presented several challenges and environmental restrictions, the flexibility of the laser guided system, paired with the auger borer and Grundoram® hammer, ensured accurate and timely delivery of the project.

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