Fullerton sits on a mix of older alluvial fans and young Holocene deposits from the Santa Ana River system, with groundwater typically shallow near the Coyote Creek corridor. That combination of variable density and high moisture makes the Flat Dilatometer Test (DMT) a practical choice here. We run the blade into the ground at a steady 20 mm/s, take the lift-off pressure every 200 mm, and get lateral stress index and dilatometer modulus on the spot. For projects near downtown Fullerton where stiff sands interbed with soft clays, we often pair the DMT with a [MASW survey](/masw-vs30/) to cross-check shear-wave velocity profiles. That saves time compared to running separate borehole tests for every layer change.
We measure horizontal stress directly in Fullerton’s alluvial clays and sands, catching loose zones that blow counts often miss.
Methodology and scope
Local considerations
We push the DMT blade with a 20-ton hydraulic rig mounted on a flatbed truck. In Fullerton’s tighter lots near the university, we sometimes need a smaller track-mounted unit to fit between fences and existing slabs. The membrane on the blade is a delicate part — one puncture from a buried cobble or old utility line and the test stops. That is why we always run a geophysical scan or a test pit first when the site has unknown fill or demolition debris. Without that step, you risk losing a full shift of data collection. We also watch for artesian conditions in the deeper aquifers below 15 m, which can push the membrane out before we even inflate it.
Applicable standards
ASTM D6635-15 (Standard Test Method for Performing the Flat Plate Dilatometer), IBC 2021 Chapter 18 (Soils and Foundations), ASCE 7-22 Section 11.4 (Site Class determination via shear-wave velocity)
Associated technical services
DMT soundings for foundation design
Continuous profiling in boreholes or direct push. We provide K0, modulus, and material index at 200 mm intervals. Output is compatible with settlement and lateral load analysis software.
DMT for seismic site classification
Correlation to shear-wave velocity (Vs) using the dilatometer modulus. Used to assign IBC site class C, D, or E in Fullerton’s alluvial basins. Includes a written report with profile plots.
Typical parameters
Frequently asked questions
How does the DMT compare to the CPT for Fullerton soils?
The CPT measures cone resistance and sleeve friction continuously, while the DMT adds a direct measurement of horizontal stress. In Fullerton’s interbedded clays and sands, the DMT gives better estimates of K0 and preconsolidation stress. The CPT is faster but does not give lateral stress directly. We often use both when the project requires settlement analysis and lateral pile design.
What is the typical cost for a Flat Dilatometer Test in Fullerton?
The typical cost for a DMT sounding in Fullerton ranges from US$860 to US$1,120 per borehole, depending on depth and access. Additional charges apply for mobilization if the site is more than 15 miles from our base. Volume discounts are available for multiple soundings on the same property.
Can the DMT be used on sloped sites or in tight backyards?
Yes, but we need at least a 6-foot-wide path for the track-mounted rig. On sloped lots near the Fullerton hills, we use a smaller unit with outriggers. The DMT blade is pushed hydraulically, so we do not need a drill rig for most soundings. We do require a cleared work area free of buried utilities.