What Is Select Fill?
Not all fill dirt is the same. On most commercial construction projects in Texas, when a geotechnical engineer specifies “select fill,” they mean material that must meet defined engineering properties — plasticity index, moisture content, compaction characteristics — documented and verified through lab testing before placement.
The word “select” is doing real work in that spec. It doesn’t just mean clean or good-looking dirt. It means the material has been evaluated, tested, and approved by the engineer of record for that specific project’s soil conditions and load requirements.
If you put non-approved material in the ground on a project that specifies select fill, you’re looking at rejection, removal, and a schedule hit that’s entirely avoidable.
Why Does Select Fill Have to Be Tested?
Every project with a geotechnical report will have soil placement specifications. Those specs define what the fill material must achieve — typically in terms of:
- Atterberg Limits (plasticity index and liquid limit)
- Proctor Compaction (maximum dry density and optimum moisture)
- Gradation (particle size distribution)
- Swell potential (especially critical in North and Central Texas expansive clay country)
The geotechnical engineer writes those requirements based on the site’s subsurface conditions and the structural loads the fill will support — foundations, slabs, pavements, utilities. The lab test on your select fill sample confirms the material you’re proposing to use will actually meet those parameters.
No approval, no placement. That’s the process on every commercial project with a geotech report.
How the Sample and Submittal Process Works
Here’s the typical workflow a contractor goes through when select fill is specified:
- Identify a potential material source — a pit, supplier, or stockpile
- Pull representative samples — typically 50–100 lbs of material per sample
- Transport samples to the geotechnical engineer’s lab
- Lab runs testing — Atterberg limits, Proctor, gradation, swell
- Engineer reviews results and approves or rejects the material
- Approved material can be ordered and delivered
The part most contractors don’t plan for: steps 2 through 5 take time. If you don’t start the submittal process before you need the material on site, you’re waiting on lab results while your crew sits.
What Aggregates Now Does Differently
Most aggregate suppliers hand you a material and walk away. If it needs testing, that’s your problem to figure out.
We built a different process.
When your project specifies select fill, structural fill, C-33 concrete sand, or cushion sand, we:
- Review your specification — we understand what the geotech is looking for before we recommend a source
- Identify the right pit — not every pit’s material will meet a given spec; we know which sources have material with the characteristics to pass
- Pull samples — representative samples packaged and labeled correctly for lab submission
- Transport directly to your geotechnical lab — expedited delivery so testing starts immediately
We’ve done this enough to know which sand pits consistently produce C-33-compliant material and which select fill sources have the right plasticity characteristics for North Texas clay subgrades. That knowledge base is what makes the process faster for you.
Materials We Source and Sample in Texas
- Select Fill — for structural fill, pad prep, and foundation support
- C-33 Concrete Sand — ASTM C33-compliant fine aggregate
- Cushion Sand — for pipe bedding and utility applications
- Pea Gravel — 3/8″ embedment stone
- Structural Gravel — drainage and base applications
Save Your Schedule. Start the Submittal Early.
The most common mistake on projects requiring material testing: waiting too long to start the submittal process. Lab turnaround takes time. If you’re ordering select fill the week you need it in the ground, you’re already behind.
Call us early. Send us your spec. We’ll review it, pull samples from the right source, and get them to your lab, so by the time you’re ready to place material, the approval is already in hand.