Downtown San Bernardino sits on alluvial fans from the San Bernardino Mountains, with dense sands and gravels near the surface, while the Lytle Creek Wash area shows looser silty sands and occasional clay lenses. That contrast matters when designing foundations for mid-rise buildings or bridge piers. The Ménard pressuremeter test (PMT) gives us direct measurement of the soil's deformation modulus (EM) and limit pressure (pl) at depth, which is far more reliable than correlations from blow counts in variable alluvium. Before we run a PMT, we often pair it with a dilatometer test to cross-check lateral stress conditions, and with CPT when we need continuous stratigraphic profiling across a parcel.
In San Bernardino's alluvial fans, the PMT's EM and pl values reduce foundation design uncertainty by up to 40% compared to SPT correlations alone.
Approach and scope
A common mistake we see locally is relying solely on SPT N-values to estimate settlement for shallow foundations on the older terrace deposits near the 215 corridor. The PMT captures the non-linear stress-strain response that SPT cannot, especially in gravelly sands where hammer energy losses skew N-values. Our procedure follows ASTM D4719-20 and uses a Menard-type probe with three cells. We inflate the probe in 10 to 15 equal-volume increments, recording pressure every 15 seconds until the limit pressure is reached. The raw curve yields three key parameters: the pressiometric modulus EM, the limit pressure pl, and the creep pressure pf. These feed directly into bearing capacity and settlement calculations per IBC 2021. In San Bernardino, we calibrate each test against local plate load tests to refine the rheological coefficient α for the alluvial soils.
Technical reference image — San Bernardino
Site-specific factors
San Bernardino's post-war expansion pushed development onto the former floodplains of Warm Creek and the Santa Ana River, where loose granular soils and shallow groundwater dominate. Without an in-situ stiffness measurement like the PMT, engineers risk underestimating settlement in silty sands with fines content above 15%, which behave differently under cyclic loading from the San Jacinto fault zone. The 1992 Landers earthquake sequence showed that liquefaction triggering in these deposits is strongly influenced by lateral stress coefficient K0, which the PMT measures directly. We always recommend a minimum of three PMT profiles per site when building on these historical floodplain soils.
EM (modulus), pl (limit pressure), pf (creep pressure)
Test depth range
1.5 m to 30 m (standard rods)
Rheological coefficient α
Calibrated per local alluvial deposits
Standard
ASTM D4719-20 / NF P94-110
Related technical services
01
Standard PMT (Ménard Type)
ASTM D4719-20 pressuremeter test using a 60 mm tri-cell probe. Reports EM, pl, pf, and creep curve for each test depth. Ideal for bearing capacity and settlement design in alluvial soils.
02
Pre-bored PMT in Cohesive Soils
For San Bernardino's clayey lenses near the 210/215 interchange, we pre-drill a 62 mm borehole and insert the probe to minimize disturbance. Provides reliable pl and EM in low-permeability strata.
03
Self-boring PMT (SBPMT)
Self-boring probe with cutting shoe to measure in-situ lateral stress (σh0) and shear modulus (G0) in soft clays or loose sands. Recommended for sites with shallow groundwater along the Santa Ana River corridor.
04
PMT for Deep Foundation Design
Vertical profile of EM and pl at 1 m intervals from 3 m to 30 m depth. Direct input for drilled shaft side friction and end bearing calculations per IBC 2021 and FHWA design methods.
What is the difference between PMT and SPT for San Bernardino soils?
SPT gives a qualitative blow count that correlates to density or consistency, but it doesn't measure stiffness or limit pressure directly. PMT provides EM and pl, which are the actual parameters needed for settlement and bearing capacity calculations. In San Bernardino's gravelly sands, PMT reduces uncertainty by a factor of 2 compared to SPT correlations.
How many PMT tests are needed for a typical commercial building in San Bernardino?
For a 50,000 sq ft building on alluvial fan soils, we recommend at least three test holes spaced 50 to 100 ft apart, with PMT readings every 3 ft from 5 ft to 40 ft depth. This covers lateral variability from old stream channels and provides a statistically reliable profile for foundation design.
Can PMT detect liquefaction potential in San Bernardino?
Indirectly, yes. The PMT measures the in-situ lateral stress coefficient K0, which is a key factor in liquefaction triggering models (Youd-Idriss 2001). Combined with SPT or CPT, PMT data improves liquefaction risk evaluation for sites in the Santa Ana River floodplain. We typically interpret PMT results alongside cyclic resistance ratios from NCEER guidelines.
What is the typical cost for a Ménard pressuremeter test in San Bernardino?
A single PMT profile with 10 readings at 3 ft intervals ranges between US$1,110 and US$1,380, including mobilization within 15 miles of downtown. Costs increase with depth beyond 30 m or if pre-drilling is required in cemented layers. Volume discounts apply for three or more test holes.
