Ocean Outfall & Submarine Pipelines

Dunedin City Council – Tahuna Beach Outfall.

Dunedin City Council – Tahuna Beach Outfall.


Christchurch City Council Outfall – Launch of pipe string for tow to storage.

Christchurch City Council Outfall – Launch of pipe string for tow to storage.


Green Island Sewer Outfall – assembled pipeline on shore prior to launch

Green Island Sewer Outfall – assembled pipeline on shore prior to launch

A large component of the work carried out by OCEL Consultants NZ Limited relates to offshore engineering, ocean outfalls and underwater pipelines. This experience has included design and detailed specification of structural components for the offshore oil industry, site selection and investigations, the obtaining of necessary consents, design, preparation of contract documents, project management, construction supervision, and advice to contractors on construction techniques.

The personnel of OCEL have been involved with a total of more than 30 submarine outfall or pipeline projects in New Zealand, Australia and the South Pacific, and several oil industry related offshore engineering projects both in New Zealand, the North Sea and Argentina. The scale of these projects ranges from multimillion dollar oil installations to small scale outfall installations that have been designed and installed by OCEL staff. OCEL has designed four of the last five major ocean outfalls – Christchurch, Dunedin, Clandeboye, Waimakariri – constructed in New Zealand in the last 10 years and is New Zealand’s most experienced engineering consultancy in the field of ocean outfalls and submarine pipelines.

Complete engineering services, including detailed design and construction supervision, have been provided for nine successfully completed outfalls and submarine pipelines. Specialist engineering advice has also been provided for several other successfully completed outfalls, both in New Zealand, Argentina, Indonesia and Australia. These outfalls and submarine pipelines have been constructed using a range of techniques specifically related to site conditions.

Of particular note are the different designs and methods of construction used for differing environments, an essential feature of offshore engineering. The varying environments involve different construction risks and exposures, and our experience reinforces the necessity to ensure that design of offshore and outfall projects incorporates an assessment of construction methods suitable to the site, and limits construction risks.

Submarine pipeline experience includes pipelay analysis work, using the OFFPIPE pipelay analysis program, and pipeline anchoring work using both concrete weights and screw anchors. OCEL has also undertaken pipeline upheaval buckling analysis work, using the ANSYS finite element program, for PT Komaritim and Total Indonesia. Ocel has a specialist program for the analysis of float and sink PE pipeline installation work.