Thursday, June 4, 2009

MCC responds to pipe fears

June 2, 2009
Dr James Wang
Ramu NiCo Management (MCC) Ltd
Madang, PNG

Dr Wang:

Several routes were investigated before the current route was selected. A new route in the mountains requires more tree cuttings and a larger scale of earthmoving which may trigger a lot of new slope-slidings and impact the ecology.

While construction along the highway still impacts the environment, the magnitude is much less.

In regards to public safety, the contents in the pipeline is Laterite slurry, a mixture of natural soil and water, which is not considered a pollutant to the environment.

If the pipeline is breached, the spillage would be washed into a river by rainfall. The river carries tons of soil to the ocean anyway.

Second, unlike gas pipelines, slurry pipelines will not explode when hit and breached by a motor vehicle. The driver and passenger could escape from the spray should it develop.

Third, the pipes are made from high strength steel alloy. The wall of the pipes laid along the highway is 2 mm thicker than the thickness required by American Slurry Pipeline Design Code B31.11, which provide extra protection from motor vehicles.

Fourth, some measures have been or will be taken in pipeline construction to prevent vehicle collision on the pipeline.

For example, the pipeline is placed 0.7m higher than the highway surface so it cannot be hit by truck bumper which is between 0.4m and 0.6m high. In most sections, a truck cannot hit the pipeline because the pipeline is behind the open drainage or buried underground.

If there is a section where the pipeline is vulnerable to be hit by a truck, an engineered safety barrier will be installed.

Most river crossings will be 1.8 m under the river bed. There are six pipe bridges above waterways which are narrow and deep. We did not realize there is a crossing which is only a couple of meters above waterway and subject to flood damage.

We would appreciate it if we could get the photos.

An advanced pipeline leak detection system is being installed on the pipeline.

There are five stations along the pipeline to monitor operating conditions. When a major leak occurs, the leak detection system will send an alarm to the pipeline operator in 30 seconds.

The operator will follow procedure to control the volume of leakage. It should be safe to say that should spill of a controlled volume from the pipeline with nontoxic soil and water mixture occur, it will not result in pollution to the waterways and harm those who rely on it for livelihood.

Best regards
Dr George Shou, PE
Chief Engineer

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