A common mistake we see among contractors in Anaheim is assuming that SPT blow counts alone define soil behavior for shallow foundations. The alluvial fans and older terrace deposits beneath the city can show similar N-values but vastly different stress histories. That is where the Flat Dilatometer Test (DMT) fills the gap. It measures the horizontal stress index, the dilatometer modulus, and the material index directly in the borehole. Without this data, settlement predictions on the silty sands and clays near the Santa Ana River corridor can be off by 30% or more. We routinely combine the DMT with a MASW-Vs30 survey to correlate stiffness profiles with seismic site class per ASCE 7, and we cross-check the dilatometer results with classification of soils to confirm the stratigraphy. The DMT is not a replacement for SPT — it is a complementary tool that reveals what blow counts hide.
A single DMT sounding yields K0, OCR, and constrained modulus in one push — three parameters that SPT alone cannot provide.
Methodology and scope
The difference between soils near the Platinum Triangle redevelopment zone and the older residential tracts around Anaheim Hills is striking. Downtown fill sequences often show a low material index (ID < 0.6) indicating clayey behavior, while the hillside colluvium yields ID values above 1.2, typical of silty sands. The DMT captures this contrast through three primary readings: the lift-off pressure (p0), the 1.1 mm expansion pressure (p1), and the closing pressure (p2). From these we derive the constrained modulus (M), the undrained shear strength (Su) in fine-grained layers, and the coefficient of lateral earth pressure (K0). The test follows ASTM D6635-15 and we deploy a 16-ton push rig with a 55° tapered blade. Each test point takes 90 to 120 seconds in soft ground, and we log the results in 20 cm depth increments. For projects requiring fine vertical resolution, we also run a resistivity survey alongside the DMT to map the stratigraphy between test locations.
Technical reference image — Anaheim
Local considerations
Anaheim grew rapidly from the 1950s onward, converting citrus groves and river floodplains into industrial parks and tract housing. Much of the area south of the 5 freeway sits on Holocene alluvium with interbedded soft clays and loose sands. The 1987 Whittier Narrows earthquake (M 5.9) caused localized liquefaction in those deposits near the Santa Ana River. When we run the DMT on those same profiles today, we consistently find overconsolidation ratios below 1.5 in the upper 6 meters, which means the soil has not been preloaded sufficiently to resist cyclic softening. Building on these layers without knowing the K0 and the horizontal stiffness is a gamble that leads to differential settlement or, worse, bearing failure under seismic loading. The DMT gives us the data to decide whether a shallow footing is safe or if ground improvement is mandatory.
Single-borehole DMT to 20 m depth. Provides ID, KD, ED, constrained modulus, undrained shear strength, and overconsolidation ratio. Ideal for small to mid-size commercial projects in the Anaheim Resort District or light industrial zones.
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DMT + SPT Combined Investigation
Alternating SPT and DMT at 1.5 m intervals in the same borehole. Correlates blow counts with stiffness parameters. Used for multi-story structures, bridge abutments, and retaining walls where both strength and deformation are critical.
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DMT Array for Seismic Site Response
Multiple DMT soundings (3–5) across the site to map lateral variability in stiffness and stress history. Includes Vs30 correlation from DMT moduli for site class determination per ASCE 7. Common in Anaheim Hills residential developments and school retrofits.
Applicable standards
ASTM D6635-15 (Standard Test Method for Performing the Flat Plate Dilatometer), ASCE 7-22 (Minimum Design Loads – Seismic Site Classification), IBC 2021 (Chapter 18 – Soils and Foundations), FHWA NHI-05-037 (Lateral Earth Pressure and Retaining Structures)
Frequently asked questions
What does the Flat Dilatometer Test measure that SPT does not?
The DMT measures the horizontal stress index (KD), the dilatometer modulus (ED), and the material index (ID). From these we derive the coefficient of lateral earth pressure (K0), the overconsolidation ratio (OCR), and the constrained modulus (M). SPT gives blow count and qualitative soil type, but it does not provide in-situ stress state or deformation modulus directly. The DMT fills that gap, especially for settlement and lateral load analyses.
How much does a DMT investigation cost in Anaheim?
A standard DMT sounding to 15 m depth in Anaheim typically ranges between US$960 and US$1,070, including mobilization within a 10-mile radius of the site. The final cost depends on the number of soundings, site access conditions, and the need for SPT alternation. We provide a fixed-price quote after a brief site review.
At what depth intervals do you record DMT readings?
We record readings every 20 cm (0.2 m) of penetration. This gives a high-resolution profile of stiffness and stress state compared to SPT, which typically samples every 1.5 m. For thin clay layers or transitions between fill and native soil, the 20 cm spacing captures variations that SPT would miss entirely.
Can DMT results be used for seismic site classification under ASCE 7?
Yes. The constrained modulus (M) from the DMT correlates well with small-strain shear modulus (G0) using established relationships (e.g., Marchetti 1980). We use that correlation to estimate Vs30 for site class determination (A through F per ASCE 7-22). When higher precision is needed, we combine DMT with MASW to validate the profile. The DMT alone is sufficient for most class C and D sites in Anaheim.
Location and service area
We serve projects across Anaheim and its metropolitan area.
