Minor Water Mains Replacement Program



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Intro

UEA has completed the installation of 4.3 kilometres of minor water mains for Shoalhaven Water. The work was located in the Nowra and Culburra Beach Region which was spread over nineteen sites of the Shoalhaven region, approximately two hours south of Sydney. The aim of these packages was to improve the water supply to a number of dairy farms, coastal towns and suburban areas.

Scope

The principal’s intent was to replace various minor water mains throughout the region of existing mains which are less than DN100 with appropriately sized mains. The packages of work was to replace existing 40mm and 50mm mains with 125mm PE, with internal diameters of 100mm.

UEA was able to offer a complete package by performing all works by internal HDD and civil crews, including:

  • Temporary water supply
  • Supply of pipe and fittings
  • Installation of pipes
  • All civil works
  • Reconnect 105 house services to the new main
  • Installation of fittings
  • Testing and commissioning of the new main

Techniques Used

The package was designed to be an open trench contract but UEA proposed the use of horizontal directional drilling (HDD), which was accepted. The use of HDD to install the main reduces the impact that the works have on the local community and also limit the disturbance to the natural surface and therefore reduce the restoration required.

To install the main, UEA used a combination of technologies including:

  • HDD – Used to install the majority on pipe work, UEA used a Ditch Witch AT3020 to install the main. This rig is small enough to complete these street works but also has the ability to complete longer shots in rural situation. It also has the ability to drill in different ground conditions.
  • Trenching – Utilised when the project included cul-de-sac heads, which HDD are unable to bend around.
  • Bed boring – Used when double driveways greater than 6 metres wide needed to be crossed.
  • Auger boring – Auger attached to excavator were used to cross small driveways, performed by internal UEA crews.

Project Challenges and Wins

UEA and the client were able review and work together to overcome any design issues before crews mobilised to site, enabling the crew’s ability to move from one site to the next without delay. UEA’s civil crew includes multi-skilled and qualified staff that have been performing this type of work for combined total of over 20 years.

UEA’s internal HDD and civil crews completed all components of the project, enabling our team to offer clients a streamlined project with only one point of contact.

The greatest issues that were encountered within the project were the different ground conditions. During these works, UEA encountered soft water charged clay, beach sand, shale and hard rock. UEA’s knowledge and experience in different ground conditions, combined with the choice of drill – one of its two DitchWitch AT3020 HDD rigs that is capable of dealing with the mixed ground conditions – meant that the team was able to overcome any foreseeable problems.