We were called to a site on Hamilton Street last year where a contractor had clipped a gas line during excavation for a new foundation. That incident could have been avoided with a proper GPR survey before breaking ground. In Allentown, where utility corridors are dense and old infrastructure maps are often inaccurate, running a Ground Penetrating Radar (GPR) scan first saves time and keeps crews safe. We pair the radar pass with a calicatas exploratorias to confirm what the antenna sees, and when the target is small we add a muestreo inalterado for soil chemistry analysis.
Allentown's dense utility corridors and variable shale soils make GPR the fastest non-destructive method to locate buried targets before excavation.
Method and coverage
Allentown sits on the Newark Basin, with interbedded shales and sandstones that can attenuate radar signals quickly. We compensate with 400 MHz and 900 MHz antennas to penetrate the fill layers common along the Lehigh River corridor. For a typical pavement scan we collect data at 0.1 ft increments and process it in real time. The ground conditions here — high clay content in the floodplain — mean we must also run a permeabilidad campo to understand moisture effects on signal depth. Our GPR survey achieves 8 to 12 ft of penetration in dry granular soils but drops to 3 ft in the saturated silts near Jordan Creek. We follow ASTM D6432-19 for antenna calibration and data interpretation.
Technical reference image — Allentown
Regional considerations
Allentown grew fast during the industrial boom of the early 1900s, and many factories buried their own steam lines, water mains, and electrical conduits without recording them. Those undocumented assets still lie under streets and parking lots today. Hitting one during excavation causes gas leaks, power outages, and project delays that run into thousands of dollars. A GPR survey maps these unknowns in hours instead of days. We also scan concrete slabs for post-tension cables and rebar — a step that prevents catastrophic tendon rupture during coring. The cost of scanning is trivial compared to one emergency repair call.
We deploy a 400 MHz antenna to trace buried pipes, conduits, and cables down to 10 ft. The data is marked on the surface in paint and logged with GPS coordinates for your CAD drawings.
02
Concrete Slab Scanning
Using a 1.6 GHz antenna, we map rebar spacing, post-tension cables, and conduits inside slabs up to 18 inches thick. The report includes depth slices and 3-D isometric views.
03
Void & Cavity Detection
We run parallel transects across suspect areas — sinkholes, backfilled trenches, or eroded subgrades — and highlight anomalies that indicate voids larger than 1 ft³. Results are delivered as interpreted plan maps.
Standards that apply
ASTM D6432-19 Standard Guide for Using the Surface Ground Penetrating Radar Method, ASTM D4748-10 Standard Test Method for Determining the Thickness of Bound Pavement Layers Using Short-Pulse Radar, ASCE 38-02 Standard Guideline for the Collection and Depiction of Existing Subsurface Utility Data
Quick answers
How deep can a GPR survey see in Allentown soils?
In the dry granular soils found along the higher terraces north of the Lehigh River, we routinely see 10 to 12 ft. In the saturated silts and clays near Jordan Creek, depth drops to about 3 ft. The shale bedrock under most of the city also reflects the signal, limiting penetration to 8 ft in those areas.
Does GPR work through asphalt and concrete?
Yes. We scan through asphalt pavement and reinforced concrete slabs up to 18 inches thick. The radar signal passes through the slab and reflects off buried utilities, voids, or the subgrade below. We use higher-frequency antennas (1.6 GHz) for slab scanning to resolve rebar and tendons.
How much does a GPR survey cost in Allentown?
A standard utility location scan for a 10,000 ft² site typically ranges between US$8.810 and US$1.430, depending on access conditions and the number of antennas required. Slab scanning adds about 15% to the base cost. Contact us for a quote tailored to your project.
Can GPR detect plastic pipes and fiber optic cables?
Yes, but with limitations. Plastic pipes and fiber optic cables produce weaker reflections than metal ones because they have a lower dielectric contrast with the surrounding soil. We adjust the gain and filtering to enhance these targets, and we always cross-check with the utility marks from your one-call ticket.
Do I need a GPR survey if I already have utility maps?
Most old utility maps in Allentown are incomplete or show approximate locations. We have scanned sites where the as-built drawings were off by 4 ft. Running a GPR survey confirms exact positions and reveals undocumented lines that do not appear on any record. It is the safest way to verify what is actually in the ground.
