Mapping & survey

Count the pile without climbing it

Drone surveys give quarries, gravel pits and aggregate yards a measured inventory, a dated record of the pit face and a report an auditor can follow. Nobody walks the stockpiles to get it.

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Why operators fly

Inventory is money sitting in piles

Every stockpile is inventory on your balance sheet. At month end or year end, someone has to say how much crushed rock, sand, base and drain rock is in the yard. Too often that number is a loader operator's estimate, an adjusted scale-house total, or a crew walking the piles with a pole.

A drone flight captures the whole yard in one pass. Photogrammetry or LiDAR turns it into a 3D surface, and each pile's volume is calculated against a base surface. The method is the same one described on our stockpile volumes page. For a quarry, the same flight also records the face, benches, haul roads and reclamation areas.

The result is a volume per pile in cubic metres, which you convert to tonnes with a bulk density for that material. That last step is where most disputes start, so we come back to it below.

Inventory is money sitting in piles: Illustration

What goes wrong

Where stockpile counts go wrong

Reconciliation that never closes

Scale tickets say one thing, the book inventory another, and the yard a third. Shrinkage, moisture and miscoded tickets pile up for months.

How we handle itA measured volume on a fixed schedule gives you a physical count to reconcile against, and the dated project record shows the trend. →

The wrong base surface

Piles sit on uneven ground or on older material. Guess the toe wrong and the volume is off by a lot on a big pile.

How we handle itWe agree the base method with you: a surveyed pad, an earlier flight before the pile was built, or a plane fitted to the toe. →

Density nobody can source

A volume is converted to tonnes with a density someone typed in years ago. The auditor asks where it came from.

How we handle itReports show the volume, the density you supplied and its source, so the conversion is visible, not buried. →

People on the piles

Walking a pile with a GNSS pole puts a person on loose, steep material near loaders and trucks.

How we handle itThe drone flies over; people stay at the edge of the yard. →

Safety

Keeping people off loose material

Stockpiles are not solid ground. Faces can slough without warning, material can bridge over voids, and a pile being drawn down from a reclaim feeder underneath can collapse into itself. Add loaders, haul trucks and conveyors working around the pile and a person on foot with a survey pole is exposed.

In British Columbia, gravel pits and quarries are regulated as mines under the Mines Act and the Health, Safety and Reclamation Code for Mines in British Columbia. The code sets expectations for working near faces, stockpiles, mobile equipment and conveyors, and for training and supervision. Other provinces and US states have their own mine and quarry rules (in the US, surface aggregate operations generally fall under federal MSHA oversight). We describe these only in general terms; your mine manager and permits set what applies on your site.

A drone does not remove every hazard. The pilot still stands somewhere on site, still needs a site orientation and still has to stay clear of equipment. But it replaces an hour on the piles with a few minutes of setup at a safe spot, and it can be done while production runs if the flight plan and the equipment routes are agreed.

Keeping people off loose material: Illustration

How the work is done

A typical inventory flight

Agree the pile list and codes

Send a yard sketch or last month's map with pile names and materials. The report uses your codes, not ours.

Set control once

Ground control points or permanent targets are surveyed in your site coordinate system. Reusing them each month keeps flights comparable.

Site orientation and flight

The pilot checks in, completes your orientation, agrees a take-off spot away from traffic and flies a grid over the yard. Wind, rain and low sun all affect results, so there is always a weather call.

Processing and pile boundaries

Processing is done in-house. Each pile toe is drawn, the base method applied and the volume calculated. Checkpoint results go into the report.

Report and files

A PDF with pile volumes, tonnage at your density, a dated map and method notes, plus the GeoTIFF and surface files. Everything is delivered by link on the project record.

A typical inventory flight: Illustration

The people around the job

Who needs the numbers

Controller or CFO

They need from you: A defensible count on the close date, in tonnes.
You need from them: The pile list, densities and the date the count must reflect.
On the DroneLink record: Fly as close to the cut-off as the weather allows and date the report to the flight.

External auditor

They need from you: A method they can understand and test.
You need from them: Their questions before the count, not after.
On the DroneLink record: The report states the method, base surface, checkpoint results and density source. Auditors can be invited to the project record.

Mine or pit manager

They need from you: Face positions, bench heights, haul roads and reclamation progress.
You need from them: Permit boundaries and any areas to avoid.
On the DroneLink record: The same flight gives an orthomosaic and surface model for planning, cut and fill and permit reporting.

Surveyor

They need from you: Control that ties to their work.
You need from them: Coordinates, datum and their review.
On the DroneLink record: We fly to their control. See LiDAR where vegetation hides the ground.

Choosing a method

Photogrammetry or LiDAR for a pit

Situation	Usually suits	Why
Open yard, bare stockpiles	Photogrammetry	Good texture and light give dense, accurate surfaces and a clear orthomosaic.
Very dark or uniform material	LiDAR or careful photogrammetry	Uniform surfaces give photo matching little to work with.
Pit edges with trees and brush	LiDAR	Laser pulses can reach ground through gaps in vegetation.
Monthly inventory only	Photogrammetry	Fast to fly and process; results compare well month to month with fixed control.
Steep faces and benches	Either, with oblique passes	Straight-down photos miss vertical faces; angled passes fill them.

Questions

How accurate are drone stockpile volumes?

It depends on control, the base surface and how well the pile toe is defined. As general industry knowledge, drone surveys with good control typically produce volumes close to conventional ground survey, and often capture pile shape better because they measure the whole surface. Each report should show checkpoint results so you can judge it.

Will auditors accept a drone stockpile survey?

Many auditors accept drone surveys when the method is documented: flight date, control, base surface, density source and checkpoint results. Ask your auditor before the count what they need to see, and invite them to review the method.

How do you convert stockpile volume to tonnes?

Multiply the measured volume by the bulk density for that material, in tonnes per cubic metre. Density varies with moisture, gradation and compaction, so use a density measured for your material, and review it periodically.

How often should a quarry fly its stockpiles?

Monthly or quarterly flights are common for inventory, timed to financial close. Busy yards with fast turnover often fly monthly so reconciliation problems show up early.

Do I need a permit to fly a drone over my gravel pit?

The drone pilot needs the right Transport Canada certificate and must follow the airspace rules for the location. Your mine permit and site safety rules also apply to anyone on site. See our Canadian drone rules guide.

Can you fly while the plant and loaders are running?

Often yes, with a flight plan agreed with the pit manager, a take-off area clear of traffic and the pilot staying out of equipment routes.

What do I need to prepare for a stockpile survey?

A list of piles with names and materials, densities, site access and orientation requirements, and any existing survey control. Piles with clean, defined toes give better volumes.

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