The difference between Arlington’s historic neighborhoods near the Potomac and the newer developments around Ballston is more than just architecture—it’s what lies beneath. In older sections, fill from past construction, buried utilities, and unknown remnants create a complex subsurface. Out toward the west, natural alluvial deposits and weathered bedrock dominate. That’s where a GPR (Ground Penetrating Radar) survey becomes essential. Unlike invasive methods, this technique maps buried objects and stratigraphy without disturbing the surface. We’ve seen projects in Clarendon where a quick scan avoided costly surprises by revealing old foundations. Pairing this with a study of test pits gives a more complete picture of what’s hiding underground. For any Arlington site, knowing the subsurface before breaking ground saves time and money.
A GPR survey in Arlington can detect buried utilities, voids, and undocumented structures before excavation, reducing project delays by weeks.
Methodology and scope
A common mistake we see in Arlington is contractors assuming that recent building permits mean the ground is clear. Old utility lines, undocumented fill, and even forgotten septic tanks can still be present. A GPR (Ground Penetrating Radar) survey catches these before equipment hits them. The method works by sending electromagnetic pulses into the ground and recording reflections from buried objects or changes in soil density. It’s particularly effective in this region because Arlington’s soils—silty sands and clays overlying fractured bedrock—produce clear contrasts. We typically run surveys at multiple frequencies: lower frequencies for deep targets (up to 5 meters) and higher for shallow detail. The data is processed on-site to mark locations in real time. This is often combined with a MASW survey to characterize stiffness profiles for seismic design. The result is a reliable map of underground conditions without digging a single hole.
Technical reference image — Arlington
Local considerations
The GPR unit itself is a rugged cart-mounted system that we wheel across the site. It consists of a control unit, antenna, and a survey wheel for distance tracking. During a project near Rosslyn, the antenna had to be adjusted for the high clay content in the soil, which can attenuate signals. We also had to work around street traffic and tight corners. The real challenge in Arlington is the mix of urban infrastructure and variable geology. Without proper calibration, you risk missing shallow utilities or misinterpreting natural features as anomalies. That’s why every survey includes multiple passes and on-site verification.
Locate buried pipes, conduits, and cables before excavation. We mark positions directly on the ground and provide digital maps for your project records.
02
Void and Cavity Detection
Identify underground voids, sinkholes, or collapsed fill that could compromise foundations or pavement. Essential for Arlington’s older districts with aging infrastructure.
03
Concrete and Slab Scanning
Scan reinforced concrete slabs to locate rebar, post-tension cables, and conduits before cutting or coring. Used in both new construction and renovation projects.
04
Subsurface Stratigraphy Profiling
Map soil layers, bedrock depth, and buried channels. This data supports foundation design and helps avoid unexpected conditions during excavation.
Applicable standards
ASTM D6432-19 (Standard Guide for Using the Ground Penetrating Radar Method for Subsurface Investigation), ASCE 38-02 (Standard Guideline for the Collection and Depiction of Existing Subsurface Utility Data), IBC 2021 (Section 1803 – Geotechnical Investigation Requirements)
Frequently asked questions
How deep can a GPR survey penetrate in Arlington soils?
In typical Arlington soils—silty sands and clays over fractured bedrock—penetration ranges from 1 to 4 meters with a 400 MHz antenna. Higher frequencies (900 MHz) provide better resolution but less depth, while lower frequencies (200 MHz) can reach up to 5 meters in dry conditions. Clay-rich soils reduce depth due to signal attenuation.
What does a GPR survey cost in Arlington?
For a standard GPR survey in Arlington, the typical range is between $1,400 and $8,140 depending on site size, number of antennas used, and the complexity of the survey area. Large commercial sites or projects requiring multiple frequency scans fall at the higher end. We provide a fixed quote after a brief site review.
Can GPR detect plastic pipes or non-metallic objects?
Yes, but it depends on the contrast between the object and the surrounding soil. Plastic pipes filled with air or water produce a clear reflection, especially in clay-free soils. In Arlington’s clay-rich zones, signal strength decreases, so we often combine GPR with electromagnetic locating to confirm non-metallic utilities.
