The plan is to remove 70 mines. The remaining mines (of which there are around 150,000) will remain untouched for now. Removing each of the 70 mines takes two days.
Interesting note from article is that this new pipeline will allow Russia to cut off supply of gas to neighbouring countries while at the same time continuing to supply europe with gas.
After the fall of USSR Rusia is in inconvenient position - it has to deal with Ukraine/Belarussia/Lativa to assure supplying Poland with Gas, and it has to deal with Poland to supply Gas to Western Europe.
It was factor that played big role in relations between these states and Russia. For example - last year Russia stopped supplying gas, because Ukraine didn't wanted to pay for gas that is uesd only for making the pipe work.
So because of Ukraine-Russia econo-war Poland didn't get the gas it paid for. Russia had to deal with Ukraine because of that. Russia often uses the pipes as economic weapon, and with the pipe beneath the Baltic sea it will be much worse - Russia will be in position to stop sending the gas to Ukraine, and nobody in Europe will give a damn. And Ukraine has many non resolved problems with Russia - like Russian ships in Crimea, big Russian "minority" in eastern regions, Ukraine wanted to NATO (or western part of it), and to UE. Now (after the blue one won) it all seems far, far away. Russia wanted Ukraine to be its "near abroad" - sth like colony. Gas pipe ommiting Ukraine will make it easier.
Of course - Russia can do with Germany what they want, but there are many political, ecological and economical concerns. And that pipe will go not only throught Russia and Germany national waters. I only wanted to give the POV of the other side.
It makes sense from a power-politics standpoint that Russia would want to be able to turn on/off the tap to Western Europe and its close-in neighbors separately. Right now when it gets into disputes with Ukraine, it can't use gas supplies as a pawn to the extent it would like, for fear of pissing off countries like Germany who are downstream on the same pipe.
