We had a project to do yesterday where a drilling company wants to drill more or less horizontally along a coal seam from an outcrop to hit a point on the interior of a research mine. So, we had to connect a point on the outcrop, which wasn't really visible but the diggings outside a groundhog hole were all black coal, so they figure that is the outcrop, to a point on the face of the coal seam in the interior of the mine. I took a couple of pictures in the mine, and then my camera died, so I only got these two. In the first, note the small rectangular opening behind the target, that was the access for us and for the sight. You can see a red light in the distance, that is the instrument.
In the map below, the magenta is the underground traverse, the red is the surface traverse, and the blue is the drilling line. Not shown yet is the static GPS we did. I tried to make everything as redundant as possible. An approximate check is that there is a drillhole just to the NW of the underground face point that we located from above and below. I do not believe it is vertical (i.e. plumb), but it is close. We located that drillhole both underground and at the surface, in the middle of the road between the buildings (with a bolted on lid, so we could not open it).
Interesting job,
no problems with the radio communication S6 - TSC2 underground?
How deep is this below the surface, looks a little scary to me. Did you use any special equipment (Zenit/Nadir) to take the traverse down?
Any special safety instructions.
thanks for sharing,
chr.
pretty tight...an all day thing with that low ceiling? Worth having a midget or two on the crew....
> Worth having a midget or two on the crew....
Actually that really would work out well but I honestly can't remember seeing any midget surveyors.
The job looks pretty fun and interesing John, thanks for the pics.
A friend told me he surveyed a tunnel (not a mine) and he said their radios would not work underground.
I have no idea why that would be.
John,
That is just "real cool".
Nice pics and good luck.
I'm positive you will nail that
And, I have a "little person" I could "lend" you in the future...
When we go back to set the final points to direct the drilling, I hope to try to use our ZNL plummet to check that borehole. I also thought about using the S6 to shoot up the borehole if it is not plumb.
The S6 radio worked pretty decent, as long as I held it in sight of the gun. As I said, we had to shoot through that hatch, which was probably 18" X 24", maybe a little bit bigger but not much. I believe it is a 2.4 Ghz radio, but not positive. My older Zeiss S10 used a 460 Mhz radio.
The guy we are working with on this project is a electronics expert, he said the higher frequencies work better. Our VHF (150 Mhz) radios were practically worthless.
I like to set references in situations like this, PK nails (reflectorless) in three nearby walls. But, one of the setups had distances to the PK's that were all ~0.06 m rather than the actual 5-10 m. Never saw that happen before, didn't notice til I was back in the office.
We only spent about 2 hours underground, most of the day was spent above ground doing GPS and traversing. I'll post more pictures after the next trip out there.
Not. In. A. Million. Years.
How did you get the GPS
to work underground? I have trouble with that.