When you pull up the following diagram:
http://kennadydiamonds.com/media/planmap_2015-05-16_faraday2.pdf

You can clearly follow Faraday 2 (F2) where from it outcrops on the eastern shore of the lake, and then makes it way across to the north-west, to almost the western shore of the lake. First as an aside, notice how small the lake is, less than 150m across, so water should never be an issue.

As the company moved north -west, they got to a point just after holes 8a/b where they lost contact with the pipe. Holes 11a and c, which were drilled vertically and @ 81 degrees respectively hit, but did not intercept the lengths one would have expected if they were in the middle of the pipe given the results from 8a/b.

So they knew they were off center when they drilled 11b at 65 degrees ( 324 degrees azimuth) where they employed an approach that worked well with Kelvin. That approach being get in the middle of the pipe and drill along the strike to maximize effieciency in proving the deposit up. 11c proved the pipe had change direction, as i clipped a mere 2.97m of kimberlite.

The question now was did it turn to the right (further north) or to the left (further west). You can see form the drill diagram that the first assumtion was to the right, further north. This was proved wrong by holes 20a/b, 25a/b, 28 and 31.

With no success they turned their attention more westerly. Hole 36a @ 61 degrees inclination was drilled and caught just over 9 meters. I suspect they immediately recognized that F2 was indeed moving west but wondered why they only caught 9 m versus say something around 50m.

Talking with the drillers they pronbably determined that the hole had deviated subtantially to the north. At that point they switched up the the casing on the drill from the smaller NQ tube to a larger HQ tube in order to keep the hole in line with the intended trajectory. 36b (shown in red on the diagram), with the HQ tube, was drilled at similiar inclination of 36a, 58 versus 61 degrees. It held it's course and caught 74m of kimberlite.

So that is a very long answer to your question. They didn't know where it was and actually guessed wrong for the first 5 or so holes. Clipped it with 36a and nailed it with 36b.

From here the company will move on to the shore to continue following F2. I suspect the next holes, once the ground stabalizes from the thaw will be collared near where 36b ended and drilled back at it as a scissor hole.

That should provide the company with a good view of the exact trajectory of the pipe.

GLTA,
Buck