The most common call we get after a rainy week in Eugene isn't about foundation design — it's about fill that failed compaction. A crew runs a smooth-drum roller over silty subgrade near the Willamette River, the nuclear gauge reads 92%, and suddenly the project stalls. The problem almost always traces back to a missing or outdated Proctor reference curve. Without a site-specific Proctor test, you're guessing at maximum dry density, and in the layered alluvium that defines Eugene's flatlands, guesswork is expensive. We run both Standard (ASTM D698) and Modified (ASTM D1557) Proctor tests from our Eugene lab, often pairing them with sand cone density checks in the field to close the loop between lab optimum and real-world lift compaction. For deeper subgrade evaluation, we'll sometimes correlate results with test pits to visually confirm soil type against the lab curve before the fill operation scales up.
A Proctor curve is not a universal constant — it's a snapshot of a specific soil at a specific compactive effort, and in Eugene's heterogeneous Willamette Valley deposits, assuming otherwise is the fastest route to a failed density test.
