Allentown sits at an elevation of 338 feet in the Lehigh Valley, where the glacial till and alluvial deposits of the Little Lehigh Creek create highly variable soil conditions. From a single CPT sounding we obtain a continuous log of tip resistance, sleeve friction, and pore pressure — information that would require multiple SPT borings and lab tests to approximate. This efficiency is critical when designing foundations for the city's ongoing industrial redevelopment and residential infill projects. Before any load is placed on these heterogeneous soils, a cone penetration test provides the uninterrupted data needed to avoid surprises during excavation. We routinely pair this technique with resistivity surveys to map subsurface anomalies before drilling begins.
A single CPT sounding can replace three SPT borings in uniform glacial till, cutting field time by half.
Method and coverage
Our CPT procedures follow ASTM D5778-20, the standard for electronic cone and piezocone penetration testing. The cone is advanced hydraulically at 20 mm/s, recording measurements every 2 to 5 cm. In Allentown’s typical soil profile — a stiff crust of silty clay underlain by loose sands and occasional gravel lenses — the CPT readily distinguishes between drained and undrained behavior. The built-in pore pressure transducer (u2 position) identifies thin sand seams that could cause differential settlement. For projects where shallow groundwater is encountered, we combine the CPT with permeability tests to evaluate drainage conditions for basement walls and utility trenches. The entire profile is classified on-site using the Robertson (1990) soil behavior type chart, reducing the need for exploratory pits.
Technical reference image — Allentown
Regional considerations
In Allentown we often see projects where the design team assumes uniform bearing capacity based on a single SPT blow count, only to find a loose sand pocket or a buried organic layer during excavation. The CPT mitigates this risk by providing a near-continuous profile. For example, in a recent warehouse expansion near the Lehigh River, the CPT revealed a 2-meter-thick soft silt layer at 6 m depth that was invisible in the pre-bid borings. Without that data, the foundation would have settled unevenly within the first year. The cone penetration test also detects thin cemented layers that can stall driven piles — a common issue in the calcareous zones east of the city.
Continuous profiling with pore pressure measurement for soil classification, groundwater conditions, and drainage estimation. Ideal for foundation design and settlement analysis in the Lehigh Valley alluvial deposits.
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Seismic CPT (SCPTu)
Adds shear wave velocity measurement to the standard CPT for dynamic site response and liquefaction assessment. Required for IBC Site Class D or E designations in Allentown's seismic zone.
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Environmental CPT (ECPT)
Equipped with sensors for electrical conductivity and pH to delineate contaminant plumes. Used for brownfield redevelopment projects on former industrial sites along the Lehigh River corridor.
Standards that apply
ASTM D5778-20 (Standard Test Method for Electronic Friction Cone and Piezocone Penetration Testing of Soils), IBC 2021 Section 1803 (Geotechnical Investigations), ASCE 7-22 Chapter 11 (Seismic Site Class using Vs or CPT correlations), Robertson & Cabal (2015) Guide to Cone Penetration Testing
Quick answers
How deep can a CPT sounding reach in Allentown soils?
In typical glacial till and alluvial deposits, we regularly reach 25 to 30 meters. The maximum depth depends on the presence of dense gravel layers or cemented zones, but our 20-tonne truck-mounted rig can penetrate most soil profiles found in the Lehigh Valley up to 40 meters.
What is the cost range for a CPT sounding in Allentown?
A standard CPT sounding with pore pressure measurement typically ranges from US$160 to US$290 per sounding, depending on depth and site access conditions. Bulk discounts apply for multiple soundings on the same site.
How does CPT compare to SPT for liquefaction assessment?
CPT provides a continuous record of tip resistance and sleeve friction, which correlates directly to relative density and cyclic resistance ratio (CRR) using the Robertson & Wride (1998) method. SPT gives only discrete blow counts every 0.3 m, making CPT more reliable for detecting thin liquefiable layers. In Allentown's sand lenses, CPT is the preferred method.
Can CPT be performed in gravelly soils common near the Lehigh River?
Yes, but with caution. Our cone is equipped with a carbide-tipped point that can penetrate up to 2-inch gravel. If cobbles or boulders are encountered, we switch to a downhole hammer system or pre-drill through the obstruction. We always assess the gravel content before mobilizing to avoid delays.
What information do I get immediately after the test?
You receive a field log showing tip resistance, sleeve friction, and pore pressure every 2 cm, along with a preliminary soil behavior type classification. A full report with corrected cone resistance (qt), friction ratio (Rf), and interpreted parameters (unit weight, undrained shear strength, OCR) is delivered within 48 hours.
Location and service area
We serve projects across Allentown and its metropolitan area.
