UEA’s Horizontal Directional Drilling (HDD) division has recently completed the underbores required as part of the Rouse Hill stage 3 secondary gas main extension project. The project required the construction of approximately 7.2 kilometres of 200mm diameter secondary steel main and the installation of two gas regulators, one at the corner of Guntawong Road and Windsor Road and the other at the corner of Hamilton Street and Campbell Street. The 200mm (219mm OD) FBE Coated Steel Gas Main was installed directly into the 350mm borehole, encased in bedrock at greater than 8.5 metres below the pavement with the void space filled with bentonite slurry as grout.
Scope of Works
As part of the project, using two Vermeer D100 HDD rigs, UEA completed three separate underbores at:
- Old Hawkesbury Road at Brennan Dam Road – 540 metres
- Old Hawkesbury Road at No. 338 – 298 metres
- Chapman Road/Bandon Road at Windsor Road – 600 metres
Taking into consideration the tight project schedule, UEA managed to successfully complete all three underbores while working through constant wet weather and changing ground conditions. Due to the unexpected soft clay ground conditions of the first two underbores, UEA had the flexibility to redesign the underbores during drilling to minimise any downtime. UEA was also able to employ the use of a second HDD rig and a variety of associated tooling to overcome the difficult ground conditions.
The longest and final underbore was in rock ground conditions, under and alongside heavy trafficable roadways. This required the steel main to be welded in two 300 metre strings – ready for the tie in weld – completed as part of the pullback process. Working with both the client and with Council, UEA piloted and reamed the underbore during standard working hours, while the pipe pull took place at night with a road closure and traffic diversions in place. UEA was able to further assist the project by using UEA’s own pipe rollers and highly skilled HDD operatives to minimise the risk of the pipe damaged during pipe pull.
For more details on this project or on UEA’s horizontal directional drilling projects, contact the Trenchless team at email@example.com or call us on 02 9672 4456.