A GPR survey produces two outputs. The first is on site: marks on the concrete or paint on the ground that the crew works to that day. The second is the report, which is what a consultant reviews before approving penetrations, what a permit file keeps, and what anyone looks at if something goes wrong later. On UAE projects the report is often the deliverable people care most about, so it is worth knowing what a good one contains and how to read it.
We issue two kinds: concrete scan reports from the Proceq GP8000, and underground utility survey reports from the Proceq GS8000. They share a structure, with differences noted below.
Job details
The first section identifies the work: site address, building and floor or plot, the element scanned (suspended slab, ground slab, wall, column, open ground, trench route), the date of the survey, the instrument used and who requested it. The date matters more than it looks. A survey describes the concrete or the ground on that day. Penetrations made or services laid afterwards are not covered.
Scope: what was scanned, and what was not
A good report draws a boundary around what was actually surveyed. For concrete, that means the zones scanned around each position, not just the positions themselves. For ground, it means the grid area or the trench corridor and its width. Anything outside the boundary was not checked, however clean it looks on the drawing. The scope is the first thing to compare against your plans: if the excavation is wider than the survey, or a core has moved outside its zone, the report does not cover it.
The findings plan
The core of the report is a marked-up layout. For a concrete scan it shows reinforcement, post-tension tendons, conduits and any voids within the scanned zones, with the positions cleared for coring or drilling. For a ground survey it shows the located services as lines with their direction, chambers and other objects, and, for larger sites, the findings drawn over your site plan.
Read the plan alongside the marks on site. They should agree. If the plan shows a tendon running through a zone that was marked clear on the slab, stop and ask before cutting.
Depths
Each finding should carry an estimated depth. In concrete that is typically measured from the scanned surface; in the ground, from the surface level on the day. Depths are estimates, because radar converts travel time to depth using the signal speed in the material, which varies with moisture. Our article on how accurate GPR concrete scanning is explains why. If you need to know the basis for a depth, ask.
Limits and confidence
This is the section that separates a useful report from a misleading one. Radar has real limits: congested reinforcement that hides what is beneath it, metal decking that blocks the signal, saline ground that cuts depth short, buried slabs that mask what lies under them. A good report names where those limits applied and how deep the survey could confirm.
A blank area on a survey means one of two things: nothing is there, or the radar could not see. A report that does not tell you which is not doing its job.
What our reports contain
- Concrete scans: marked-up layout of the scanned zones, position and depth of the bars, tendons and conduits found, the positions cleared, and the limits that applied. Issued as a PDF within 24 hours of the visit. 3D scan data from the GP8000 on request.
- Ground surveys: the survey area, located services with estimated depths, services found that are not on the drawings you gave us, and the areas where the ground limited the reading. Issued as a PDF within 24 hours, with a marked-up drawing over your site plan for larger sites.
Concrete and ground reports: the differences
A concrete scan report is organised around positions: each planned core or fixing, the zone scanned around it, what was found inside that zone and whether the position is clear. Its readers are usually a structural engineer or a building's facility management, and the key question is whether a hole can go here. A ground survey report is organised around routes: each located service as a line, its direction and estimated depth, and how it compares with the record drawings. Its readers are usually the excavation supervisor and whoever holds the permit, and the key question is where it is safe to machine dig and where to hand dig. Both should state their limits in the same plain way.
How to read a radar trace
Some reports include radar sections, the grey-scale images the instrument records. Each one is a slice through the material along one scan line, with distance along the line across the page and depth down the page. A buried object crossed at right angles appears as an arch. The top of the arch is the object's position and depth. A row of evenly spaced arches is usually a bar layer; a group of closely spaced arches whose depth changes from one line to the next is typically a tendon band. In ground surveys, a strong flat reflection can be a buried slab or a hard layer, and anything beneath it may be hidden.
Red flags
- No date, or no instrument named.
- No boundary showing what was and was not surveyed.
- Every area shown as equally clear, with no stated limits.
- Depths given as exact figures with no indication they are estimates.
- A ground survey that claims full depth on saline coastal ground or sabkha.
- Findings on the report that do not match the marks on site.
How long a report stays valid
A report describes the element or the ground on the day it was surveyed. For concrete, it stays valid for the positions it cleared as long as nothing has changed: no new penetrations nearby, no change of core position or diameter. For ground, other trades laying services after the survey make it out of date for that area. When in doubt, rescan the affected area. It costs far less than a strike.
Getting a report your consultant will accept
If your building management, consultant or permit has specific requirements, send them when you book and we will make sure the report covers them. Book GPR concrete scanning or a GPR ground survey anywhere in the UAE, or see concrete scanning in Dubai and underground utility survey in Dubai. For what to prepare before a concrete scan, read GPR scanning before core drilling.