Kiama Sewer Main Installation

UEA was engaged by a developer to install a 180mm PN16 gravity sewer main from a new development to the existing gravity sewer system in the township of Kiama NSW.

Scope Of Works

UEA was contracted to supply two HDD installations, both at 3% grade. Limited access and a constant horizontal curve also added to the complexity of the project.

• Bore 1 – 230 metres of 180mm PN16, SDR 11
• Bore 2 – 180 metres of 180mm PN16, SDR 11

Challenges

Kiama was the site of two strong volcanic flows called the Gerringong Volcanics, which attributed to the local ground conditions. The rock that the new sewer main was installed through is known as Latite, an igneous volcanic rock which forms during the cooling and solidification of lava. Due to the lava cooling in this process, the rock formed with no seams, making it difficult to excavate or drill. In this circumstance, the rock strength was tested as 250Mpa.

Completion

UEA worked with the client and Sydney Water to modify the design and set up locations so as to enable the best result. Due to the prior knowledge of the rock strength, UEA was able to purchase specialised rock drilling heads and reamers. With UEA’s expertise and with the right tooling, the bore was completed to the exact grade and location and with one happy client.