Question 1

How Accurate Are the Results of Ground Penetrating Radar?

Accepted Answer

GPR is extremely accurate! While accuracy is reliant upon various external factors such as ground and soil conditions, Sentry Mapping’s standards ensure that we are able to obtain the best results possible in each situation. Through past experience, when using a utility locating antenna for scanning, the accuracy is +/- 6 inches to the center of the object being located and +/- 10% to the actual depth.

Question 2

Are GPR cemetery surveys safe for areas with fragile historic headstones?

Accepted Answer

Yes. GPR cemetery surveys are completely non-invasive: the radar cart rolls across the turf without touching monuments, and the radio waves are lower power than a cell-phone call. Sentry Mapping’s process leaves the soil, turf, and even the most fragile 1800s marble or sandstone headstones untouched.

Ground penetrating radar cemetery mapping is one of the gentlest ways to investigate historic burial grounds.

Sentry Mapping’s high-frequency GPR antennas transmit a brief, low-energy radio pulse through the soil and listen for reflections—it is the same non-ionizing energy used by Wi-Fi, so it poses no risk to people or stone. Because the equipment is pushed like a stroller across the grass, there is no vibration, excavation, or chemical applied; nothing ever touches the fragile markers.

The result is a full subsurface map that shows every marked and unmarked grave while leaving the site exactly as we found it. GPR does not emit any harmful radiation. The area can remain undisturbed during the course of the scan and causes no soil disturbance or any other damage to the site.

We have successfully mapped many cemeteries dating back 150+ years without any damage to headstones and markers.

Question 3

Can GPR Be Used to Locate Unmarked Grave Sites?

Accepted Answer

Yes. High-frequency ground penetrating radar (GPR) can pinpoint unmarked graves without digging by detecting disturbed soil, coffins, or voids below the surface. Sentry Mapping’s cemetery GPR surveys deliver precise GPS coordinates, letting you update burial plot maps and avoid accidentally disturbing unknown interments.

Ground penetrating radar cemetery surveys are today’s gold standard for unmarked grave detection. Sentry Mapping rolls a high-frequency GPR cart in a tight grid over the turf. The radar sends short radio pulses into the ground; a laptop instantly logs reflections caused by disturbed soil layers, coffins, vault lids, or air gaps. Each anomaly is tagged with centimeter-level GPS so you know the exact burial plot location.

Because GPR is totally non-invasive, your grounds remain undisturbed and respectful. In most sandy or loamy soils it can resolve grave features down to about 10 ft deep. Heavy clay or saturated ground can reduce clarity, but our specialists adjust antenna frequency and survey pattern to maximize results.

When the fieldwork is done, we merge every radar hit into our digital cemetery mapping workflow: an easy-to-read master map, an online cemetery GIS map visitors can search, and two free years of Chronicle cemetery management software. Staff can click any plot to see who is buried there—or flag an unmarked grave that needs a new record—eliminating the risk of selling an occupied lot.

Whether you manage a 100-acre municipal cemetery or a small churchyard, professional cemetery mapping with GPR protects heritage, guides maintenance crews, and gives families confidence their loved ones rest undisturbed.

Question 4

Is Ground Penetrating Radar Safe to Use?

Accepted Answer

Yes. Ground Penetrating Radar (GPR) is considered safe for operators, cemetery staff, and visitors. The equipment uses very low-power radio waves—about one-thousandth the strength of a cell phone—so it does not disturb human remains, monuments, or nearby electronics. Surveys are noninvasive, silent, and require no digging.

Ground Penetrating Radar transmits non-ionizing radio pulses (typically 250–900 MHz) through the soil and measures the echoes. The power output is less than two watts—roughly the same as a household Wi-Fi router—so it poses no radiation or electrical hazard to people, animals, pacemakers, or headstones. Because the signal loses strength within a few feet of the antenna, nothing outside the immediate scan line is affected.

During a Sentry Mapping cemetery survey, certified technicians push a lightweight GPR cart across the turf. There is no drilling, excavation, or contact with caskets, meaning remains stay undisturbed and the landscape shows no evidence of the work once the wheels roll past. All equipment meets FCC Part 15 emission limits, and our team follows OSHA and cemetery-industry best practices for PPE, site control, and respectful conduct.

The result is a completely non-destructive way to detect unmarked graves, confirm plot boundaries, and digitize records. Managers get precise GPS-tied data for every burial, plus an interactive cemetery GIS map and two years of free Chronicle cemetery management software—without risking visitor safety, staff health, or the integrity of historic sites. In short, GPR delivers the safest, most reliable path to modern, professional cemetery mapping.

Question 5

What is the difference between a “burial-plot map”, a “web-map”, and a “GIS survey”?

Accepted Answer

A burial-plot map is the precise, static master layout of every grave and available space, produced from a one-time GPR/GPS survey. A web-map is the online, clickable version of that map that staff and families can access online to search from any device. A GIS survey is the underlying field data-collection process that feeds both products.

Think of the three deliverables as steps in one streamlined cemetery-mapping workflow.

1) During the GIS survey, Sentry Mapping technicians walk every row with survey-grade GPS and ground-penetrating radar equipment. The instruments record x-y coordinates, depth readings, and attributes—marked and unmarked grave locations, utilities, pathways, trees—creating a rich spatial database. This is the foundation of professional cemetery GIS mapping and integrates seamlessly with municipal or county GIS systems.

2) We produce the burial-plot map from the GIS survey data. This is the authoritative, to-scale master plan you can print, frame, or keep on the grounds. Every lot line, section number, and interment is plotted in its exact position, so you instantly see which plots are occupied, reserved, or available for sale.

3) We then publish the same data as an interactive web-map so your staff, grounds crew, and even visitors can zoom, search a name, or tap a grave for details on a phone or tablet. The web-map lives in the cloud, receives free updates when new burials are added, and links directly to Chronicle’s cemetery management software for digital record-keeping.

Together, the GIS survey, burial-plot map, and web-map turn outdated paper charts into a living, searchable, digital cemetery mapping system that eliminates double-sold plots, speeds grave locating, and preserves your cemetery’s heritage for generations.

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Sentry Mapping Services’ extremely accurate cemetery mapping provides the best visualization for both visitors and management to find what they are looking for.

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