Hi Luigi

There are two methods for this sort of shallow water pipeline over relatively short distances.

1.  Push out from an onshore anchor point using pipe jacks.

2.  Float out using bouyancy tanks.

If using the push out method you will need to dredge the channel and then install temporary guide piles along the line.

If floating out you will have to drag the bouyant pipes along the dredged line before sinking into the trench.

Dredging can be done from a 360 backacter on a shallow barge - piling can be done from a similar rig.

In any case the pipes will have an ante floatation concrete casing.

Production is governed by the welding and this is determined by whether you are using automatic or semi automatic methods.

With such a relatively small pipe 500m a day is acheivable using automatic welding and 200m a day for semi.

Hand welding would achieve less than 100m.

So the entire 1100m pipe can be laid in 3-4 days.

In either process you can only work during daylight so a 24 hr rolling shift would not be possible.

The process is continuous in the following sequence.

String pipes to the welding position from the stockpile using cranes and rollers.

The pipe is moved - either pushed or pulled through the welding stages

The welded areas are tested and then jointed.

A FOC cable is usually strapped to the pipe

If pushed the pipe is guided along the trench underwater.

If pulled the entire length is positioned over the trench and then sunk.

The trench is then backfilled (after removal of any guide piles) - depending on the tidal conditions the trench can be expected to silt up in anything up to 21 days.

I hope that helps,

Best regards

Mike Testro