Frisco’s geology shifts noticeably as you move east from the Dallas North Tollway toward Lake Lewisville. On the tollway side, you’re often dealing with the stiff, lean clays of the Austin Chalk formation, while just a couple of miles east the soil transitions into the looser sands and silts of the Eagle Ford group. A standard Atterberg limits test catches the plasticity change, but it won’t tell you the full story. For that, you need a complete grain size analysis covering both the coarse fraction retained on the No. 200 sieve and the fine fraction that passes through. Our lab in the area runs the full curve—mechanical sieving per ASTM D6913 and hydrometer testing per ASTM D7928—so engineers get a single, defensible soil classification instead of guesswork.
If you’re only running Atterbergs on Frisco’s transitional soils, you’re missing the gradation story that drives drainage and compaction behavior.
Local geotechnical context
Frisco’s 2015 population sat around 155,000; by 2023 it passed 230,000, and the city keeps annexing land north toward US 380. That pace of growth means construction is pushing into areas with less geotechnical characterization, where you’ll find erratic lenses of alluvium and residual soil that don’t match the boring logs from a subdivision built two blocks away. Skipping a full grain size analysis in these fringe zones is a bet on uniformity, and that bet loses when a silty sand pocket under a corner of the slab consolidates differently than the clay under the rest of the floor. Even on interior lots, the difference between a well-graded sand (SW) and a poorly-graded sand (SP) can be the difference between a straightforward compaction spec and a material that needs replacement. The hydrometer portion matters here too—Frisco’s clays can run 60% or more passing the No. 200 sieve, and without that data you can’t reliably assign a USCS group symbol or estimate the soil’s drained behavior.
Quick answers
What’s the difference between a sieve analysis and a hydrometer analysis, and do I always need both?
A sieve analysis covers particles larger than 0.075 mm (retained on the No. 200 sieve) and gives you the coarse fraction distribution. The hydrometer analysis handles everything smaller than 0.075 mm—the silts and clays—by measuring settlement rates in a liquid suspension. If your material is mostly sand with almost no fines, a sieve alone may be enough. But in Frisco, where soils often have significant clay content, you almost always need both to get a complete curve and a reliable USCS classification.
How much does a combined sieve and hydrometer test cost in Frisco?
For a combined analysis covering both the coarse and fine fractions, you’re generally looking at US$90 to US$210 per sample, depending on whether we’re running a full hydrometer with multiple readings or just a single-point determination. The price includes the gradation report, the USCS classification, and a brief interpretation note if you want one.
How long does the lab take to turn around a grain size analysis?
A standard sieve analysis can be turned around in 24 hours if we receive the sample by mid-morning. The hydrometer portion takes longer because the soil needs to be dispersed and the readings are taken over a 24-hour settlement period, so a combined report typically goes out in two to three working days. We can expedite to next-day on the hydrometer if you’re really jammed up—call ahead and we’ll tell you if the schedule allows it.
Can you classify the soil if the sample comes from a job site outside Frisco but still in the DFW metro?
Absolutely. We run grain size analyses on samples from across Collin County, Denton County, and the broader DFW area. The testing standards are the same, and we’re familiar with the regional geology from the Woodbine sands in the east to the Grayson Marl in the west, so the classification and any commentary on expected behavior will still be locally relevant.
