Grain Size Analysis (Sieve + Hydrometer) in Santa Ana

ASCE 7 and the California Building Code require site-specific soil classification for any new construction in Santa Ana. We use grain size analysis (sieve + hydrometer) to determine the exact particle distribution of the soil. This data is critical for assigning the correct site class under IBC 2018. Santa Ana sits on deep alluvial deposits with interbedded clays and sands. A poorly classified soil can lead to an incorrect seismic design category. We follow ASTM D422 for the full hydrometer curve and ASTM D6913 for the sieve portion. Before we recommend any foundation solution, we first confirm the soil type through this test. It pairs well with a full study of soil mechanics to define shear strength and consolidation behavior.

A missing hydrometer curve on a fine-grained soil can hide up to 30% of the clay fraction, leading to a misclassification of the site.

Scope of work in Santa Ana

The climate in Santa Ana is arid, with less than 350 mm of rain per year. But the groundwater table can be shallow near the Santa Ana River. That moisture variation affects the fines content measured during hydrometer analysis. Here is how we run the test:

Sieve separation down to No. 200 sieve (0.075 mm)
Hydrometer sedimentation in a controlled-temperature bath for the clay fraction
Correction for dispersant and temperature per ASTM D422
Combined gradation curve with D10, D30, D60 and uniformity coefficient

We also check for organic content if the soil is dark. For pavement subgrade evaluation, we often combine this with a CBR test to assess bearing capacity under soaked conditions. The full picture comes from integrating the gradation with Atterberg limits.

Grain Size Analysis (Sieve + Hydrometer) in Santa Ana

Parameter	Typical value
Sieve range	3 in. (75 mm) to No. 200 (0.075 mm)
Hydrometer range	0.075 mm to 0.001 mm
Sample mass (sieve)	500 g (fine) / 5000 g (coarse)
Dispersant	Sodium hexametaphosphate (40 g/L)
Sedimentation time	Reading at 0.5, 1, 2, 4, 8, 15, 30 min, 1, 2, 4, 8, 24 h
Correction applied	Meniscus, temperature, dispersant, and hydrometer calibration
Report output	Particle size distribution curve + USCS classification per ASTM D2487

Risks and considerations in Santa Ana

A contractor we worked with near the Civic Center skipped the hydrometer portion and classified a fat clay (CH) as a lean clay (CL). The foundation design underestimated the swelling potential by a factor of two. That mistake cost them a slab replacement six months later. In Santa Ana, the shallow soils often contain expansive clays from the older alluvial fans. Without the full hydrometer curve, you miss the fraction below 0.002 mm — the active clay. The sieve alone cannot separate silt from clay. We always run the full grain size analysis (sieve + hydrometer) for projects west of Harbor Boulevard, where the clay content is historically higher.

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Applicable standards: ASTM D422-63 (2020) — Standard Test Method for Particle-Size Analysis of Soils, ASTM D6913/D6913M-17 — Particle-Size Distribution (Gradation) of Soils Using Sieve Analysis, ASTM D2487-17 — Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System), California Building Code (CBC) 2022 — Chapter 18, Soils and Foundations

Our services

We deliver three complementary services around grain size analysis in Santa Ana:

Full Gradation Curve (Sieve + Hydrometer)

Complete particle size distribution from 75 mm down to 0.001 mm. Includes USCS classification, coefficients of uniformity and curvature, and a professional report stamped by a licensed geotechnical engineer.

Hydrometer Analysis Only (Fine Fraction)

Targeted sedimentation test for the fraction passing No. 200 sieve. Used when only the clay and silt content is needed for plasticity or consolidation assessments. Runs per ASTM D422 with full temperature corrections.

Sieve Analysis for Aggregates and Coarse Soils

Dry or wet sieve up to 3-inch openings. Suitable for base course, backfill, and coarse-grained soils where the fines content is below 5%. Reports gradation to Caltrans or local agency specs.

Q&A

What is the difference between sieve analysis and hydrometer analysis?

Sieve analysis separates soil particles down to 0.075 mm (No. 200 sieve). The hydrometer analysis measures particles smaller than that, down to 0.001 mm, by measuring the sedimentation rate in a water column. In Santa Ana soils, the hydrometer is essential because the clay fraction often controls the swelling behavior.

How much does a grain size analysis cost in Santa Ana?

The typical range for a full sieve plus hydrometer test in Santa Ana is between US$100 and US$200 per sample. This includes sample preparation, the sedimentation readings, and a complete gradation curve with USCS classification. Volume discounts apply for projects with more than 10 samples.

How long does the hydrometer test take?

The sedimentation readings span 24 hours, with the first reading at 30 seconds and the last at 24 hours. The total turnaround for a full grain size analysis (sieve + hydrometer) is typically 3 to 5 business days from sample receipt. We can expedite to 48 hours for an additional fee.