I have a client who owns the mineral rights to some property with a limestone quarry on it. The quarry covers other owners' property as well. I need to be able to verify the tonnage removed from my client's property. The mining company is providing aerial mapping quarterly. They are also keeping shot records and are trying to verify the shot records with the photography. Property boundary is established and mapping is on the same coordinate system. At the time this company purchased the quarry last year, all of the mining had been done on my client's property, so all the rock was his. Now it is coming from other adjoining properties as well, all in the same pit. None of the rock is weighed, except for belt scales, as it is crushed, blended, and loaded on barges. And it may come from either property.
It seems it would be a simple matter to just compare each mapped surface to the previous one, only include the area of the property, deduct any fill from the total excavation, and come up with the yardage. However, this in no way compares to the shot records. For example, once a shot is finished, the rock produced may or may not be immediately removed. It may be used to build ramps. It may still be partly laying in the area the shot records include. And, the volume of the blasted rock is swelled by some unknown percentage from the volume it was before blasting.
I'm thinking comparing the surfaces is the only way to ultimately know how much rock has been removed. Even better would be to compare each surface to the original surface (rock surface with overburden removed) and deduct the previous totals each time. That way there is no overlapping where rock may get moved but not removed. At some point, all the shot rock would be removed, and whatever variances there were from month to month would correct up then.
Anybody else doing anything like this, or have other suggestions? I think trying to verify the shot records with the mapping is not the way to go.
Worked for a company in the 80's in Upstate NY where once a year we would topo the quarry as well as the designated stockpiles for volume calcs. I only did the field work, drafting and calc's, what happened with the numbers after was not my area. I can at least give you some contact info, but don't know how much they'le divulge.
If you want to give it a try, email is in my profile.
...yes sounds similar to a job I did on a nuclear bomb site where we had to cover toxic waste with huge mounds of fill. The contractor was paid on volume of fill moved. So I did an original topo survey of the area where we would extract the fill and then a final topo survey after the extraction 3 months down the line. And as the mounds over the toxic waste built up I would topo those as well maybe 3 or 4 times until it reach its specs. So we didn't work from an aerial map as our basis. But that being said ..I would send my volume comps to the Department of Energy's guy who would check them against aerials because they were going to foot the bill...government project an all. There were discrepancies but small enough not to matter....
I didn't do any of the calcs but did do the field work a couple of times. I remember us scrambling around to find the topo boot for the rod. It didn't seem like a big deal to me at the time. We were going to do sand or mica or lime or some fine mineral like that. When I realized the rod might stick in a couple tenths on each shot covering about 5 acres it ocurred to me that would be a huge difference in volume.
Photogrammetric mapping at one-foot contour intervals yields volumetric calculations accurate to ±2% of actual volume. However, the control has to be consistent from one flight to another.
Prof. Cliff....
Are you talking about a LIDAR flyover?
My understanding is it doesn't much care highly reflective material.
What if we were doing a mica pit which is common in Mitchell County NC where we had that one job I was thinking of.
No. Not talking about LIDAR. Talking about old-timey aerial photography and stereoscopic contouring. I did it for years back in the 1970s. Pretty simple stuff if you have the equipment. They still do it nowadays, but with "softcopy photogrammetry" in stereo on PC computers.
Cliff
It has been a very long time since I have used a Kelsh plotter (that name should tell you how long) and I have a question for you.
Has the technology of the field advanced far enough to now have the contours traced automatically or are they still traced by hand on a computer?
Cliff
There is "automatic" terrain-matching software, but for critical applications like stockpile volumes, they're still pushing the dot by hand.
I've actually done quite a bit of this, but usually it's just comparing DTMs. I think that's the way to go here, and forget the shot records. When they lay out a shot pattern, they usually just measure over from the edge of the existing highwall. Then when the shot goes off, there is some backbreak behind the last row of holes that wasn't included. Then the next holes are laid out from that new highwall. If they gain 3 feet per shot, pretty soon you've lost 30 feet of rock on a 600 foot long highwall 70 feet high. That's over 100,000 tons of rock.
Cliff
Ditto with Cliff. Been there ...done it. Don't make things any harder than need be...listen to'em...:)
I am currently working in a copper mine. We do weekly surveys of toes (high wall) and crest of the bench being mined. Our volumes are based on preblast surfaces. As mentioned before, the entire bench is not mined out. We take 50' levels at a time leaving 20' catch benches. The mapping program we use calculates the remaining tonage on the benches. If you have any questions or would like greater detail, please feel free to contact me. dah75961@yahoo.com or david_haver@fmi.com. Just put mining volumes in the subject.
