i have a project that i discussed with Zach at Drone Deploy earlier and thought we could get some additional feedback on this forum.
i am tasked with calculating the amount of fill that has already been applied to a golf course that’s under construction. My client wants to calculate the amount of fill that’s been applied and compare it to the original specifications.
From talking to Zach, we discussed using the Cut and Fill properties in DD, but since we do not have a “pre condition” image, i don’t see how that would work.
My plan now is to GPS areas where Topsoil hasn’t been applied and and use those elevations to determine how much higher or lower the areas are with Topsoil applied.
Does anybody have any suggestions or comments on this method?
Thanks in advance.
Without a pre-existing accurate model of the terrain, you are not going to be able to calculate the cut and fill thickness to any degree of workable accuracy. I have done similar calculations for rehabilitation of mine sites, but I have always had LIDAR or some other form of photogrammetry of the original surface before work started. GPS measurements of surface elevation are no good for what you want; GPS accuracy in elevation at best is +/- 5 to 10m unless you have an augmented system running (DGPS or RTK). You could get a surveyor to pick up the ground points and get centimetre accuracy - but will you have enough points to estimate thickness over the entire golf course? Google Earth has digital elevation data, but again it is not going to be accurate enough for your needs.
Has the topsoil been laid to a specified thickness? If less than a metre thick, then you could drill some test holes on a grid to check depth, but even with this method you are still only going to get a rough estimate of top soil applied. I have had to do this once to prove to a government department that the correct thickness of fill had been applied over exploration tracks and drill pads.
Tough job without the “before” surface data. Did the contractor providing the fill supply you with truck tonnes or number of backloads? You could work out an average fill depth from this.
desertoak, i appreciate the response…
you’re right, i do not have any kind of pre-model of the terrain. I DO have RTK GPS so i am able to get 1-3 cm horizontal and 6-9 cm vertical accuracy. This gives me another idea, that i could possibly use the site survey points to get some kind of base in these areas.
Well, the topsoil was SUPPOSED to have been delivered to a specific thickness, but that’s one of the things we are verifying. I will be less than a meter thick, so i think testing some of the holes on a grid, along with capturing elevations on “unseeded” areas would give me a workable “base”? The base will be fairly rocky, so i should be able to get pretty close to the base layer with these drilling cores.
i may be able to get the load the data from the contractor too, which would give me an estimate of how much fill is required in comparison to what’s actually there.
Please let me know if you have any additional comments or suggestions,
V/R,
D
OK, sounds like you have the tools to take some accurate measurements. How compacted is the topsoil? Can you use a steel probe marked with depth to find the original surface rather than having to drill? I am sorry I don’t have a more drone-based solution for you, but DD can at least provide the area for any polygons you mark out.
Did the contractor use a grader to spread the topsoil and did the grader have RTK GPS fitted? If so there may be some useable surface data there.
Thanks again Darin.
i’m not sure about the topsoil, I went out there for a site review about 2 months ago, but alot has gone one since then. However, i think i’ll be able to drill or get a probe to the topsoil like you say.
When i bid this, i wasn’t even going to use a drone, except maybe as a validation and measurement tool, but i thought there may be to get a soil depth after using my drone lately on some other projects.
Anyway, I really appreciate your comments, they’ve been very helpful in getting me to think more through the process.
Have a great day.