ASTM D4318 is the foundation of fine-grained soil classification, and in Savannah, it’s not optional—it’s essential. The city sits on the Atlantic Coastal Plain, where marine and fluvial deposits create layers of silt and clay that behave very differently under load. A soil you’d call ‘firm’ in the morning can turn plastic by afternoon if the moisture content shifts. Our lab runs Atterberg limits on every sample from the Savannah metro, from Pooler to the islands. We’ve seen liquid limits swing from 35 to over 80 within a single boring on Bay Street. Without a precise grain size analysis paired with the plasticity data, you’re guessing on bearing capacity. And guessing in Savannah’s high water table zones leads to differential settlement that shows up fast in the humid subtropical climate.
In Savannah, the plasticity index isn't just a number—it's your first warning about shrink-swell potential in the city's marine clay layers.
Method and coverage
Regional considerations
We run the Casagrande cup on a calibrated granite base inside a humidity-controlled lab just off I-16. The brass cup drops precisely 10 mm every time—no wobble, no drift. Why does this matter in Savannah? Because if the liquid limit is off by just three points, your USCS classification can flip from CL to CH. That changes your allowable bearing pressure by hundreds of pounds per square foot. We’ve seen reports from other labs where the plastic limit was rushed—threads rolled too fast, too thick—and the resulting PI was useless. When you’re designing a mat foundation near the Savannah River, where the soft clay extends 40 feet deep, that error multiplies into a structural problem. Our technicians run duplicate tests on every sample. If the two liquid limit values differ by more than 5%, we run a third. No shortcuts. The equipment gets verified weekly with reference soil samples from the Georgia Tech geotechnical program.
Process video
Standards that apply
ASTM D4318-17: Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils, ASTM D2487-17: Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System), AASHTO T 89-22: Standard Method of Test for Determining the Liquid Limit of Soils, AASHTO T 90-22: Standard Method of Test for Determining the Plastic Limit and Plasticity Index of Soils, IBC 2021 Chapter 18: Soils and Foundations
Complementary services
Liquid Limit Determination
Multi-point Casagrande cup method per ASTM D4318. We plot flow curves from four data points between 15 and 35 blows for accuracy.
Plastic Limit & Plasticity Index
Hand-rolled thread method by experienced technicians. We report PI to the nearest whole number and classify per USCS.
One-Point Liquid Limit
Available for projects with tight timelines where a full flow curve isn't required. We validate against multi-point results monthly.
Full Atterberg Package with Grain Size
Combined LL, PL, PI and sieve/hydrometer analysis. Delivers complete USCS classification and soil behavior assessment in one report.
Typical parameters
Q&A
How much does Atterberg limits testing cost in Savannah?
For routine projects in the Savannah area, a standard Atterberg limits test (liquid limit and plastic limit) typically ranges from US$60 to US$110 per sample. The exact price depends on the number of samples and whether you need a rush turnaround. We can provide a firm quote once we know the project scope.
What's the difference between liquid limit and plastic limit?
The liquid limit is the water content where soil changes from a plastic state to a liquid state. We determine it using the Casagrande cup—counting the number of blows to close a standard groove. The plastic limit is the water content where the soil crumbles when rolled into 3 mm threads. The difference between them—the plasticity index—tells us how sensitive the soil is to moisture changes. In Savannah's marine clays, a high PI signals significant shrink-swell potential.
How long does it take to get Atterberg limits results in Savannah?
Our standard turnaround is 2 to 3 business days from sample receipt. We can expedite results within 24 hours for time-sensitive projects, such as active excavations in downtown Savannah where the contractor needs immediate classification data. The soil must be oven-dried and sieved before testing, which adds a few hours regardless of priority.