Trenchless Australasia visited the site, meeting with Jacquie Sharples and Colin Hess from Yarra Valley Water, Site Foreman from MFJ Constructions Marino Mustica, and Andrew Holman from Global Pipe.

The project will link existing sewerage infrastructure with 20 kilometres of new sewer pipeline from Campbellfield to Epping and Craigieburn. The entire sewerage project will be built in stages over the next 10 to 15 years. It will service the numerous commercial/industrial and residential estates planned in the area.

The current works include:

  • Lalor – two kilometres of sewer is under construction using open trench and boring methods on land being developed for the Carlingford and Mosaic Living residential estates.
  • Campbellfield – a two kilometre tunnel section of sewer running along open space from Horne Street, Campbellfield to just east of Hume Freeway.

HOBAS chosen for stage 2

Stage 2 of Epping Branch Sewer was designed for a GRP thin walled pipe, however the construction contractor could choose any approved equivalent pipe as part of his tender. Based on the best value for money, the successful tenderer chose to supply and install DN1,000 HOBAS CC-GRP. Global Pipe is the exclusive supplier of HOBAS CC-GRP jacking pipe in Australia.

Construction on the project began in May 2009. The Epping sewer combines 1,143 metres of open trench and
877 metres boring using HOBAS jacking pipe. The ground condition for the bore is mostly solid basalt. The contractor on the project is MFJ Constructions.

MFJ Constructions has worked with the product previously. The CC-GRP jacking pipe has the advantage of relatively smaller outer diameter, meaning a smaller bore, less excavation and money saved.

“Of particular interest are the lower machine costs and reduced excavation due to the smaller outside diameter that is a by product of the thinner pipe walls,” says Mr Holman.

The HOBAS pipe consists of a thermosetting composite material. During the automated centrifugal casting process, several components of the compound material are fed into a rotating mould, degasified by rotation with a pressure of 30 to 50 bar, compacted, and tempered.

A smaller drill hole automatically means that less ground material has to be removed, transported and disposed. The result is considerable savings in excavation work that can amount to 14 to 53 per cent depending on the nominal diameter. The smaller drill hole will often translate into reduced boring costs.

The other major benefit is the inherent flexibility in CC-GRP Mr Holman said “The pipe is able to compensate for minor irregularities in the face of the machinery or bore by means of elastic deformation. This elasticity also means that no timber or particle board spacer rings are needed in the joint.

“The use of timber spacer rings should be considered the weak link in any jacking project as they typically prevent the joint from fully closing and are left in the joint to swell and then deteriorate faster than the rest of the pipe system.”

A strong partnership

The ECSP is a long term sewer improvement project. Challenges overcome on the project include the mostly solid basalt ground conditions and the large diameter of the pipe.

The new sewer system will assist in servicing more than 38,000 residential lots and approximately 1,500 hectares of industrial and commercial development in northern Melbourne.