Memphis sits atop the New Madrid Seismic Zone, where liquefiable sands and silts are common in the alluvial plain. The water table is often shallow here, sometimes less than 10 feet, which complicates sampling. We run SPT according to ASTM D1586-18 using an automatic hammer on a CME-75 rig, extracting split-spoon samples at 5-foot intervals. In deeper Holocene deposits east of the Wolf River, blow counts can drop below 5 in loose sands, triggering the need for liquefaction analysis per NCEER guidelines. Samples are logged in our AASHTO-accredited lab for grain size and fines content the same day.
In the Mississippi Embayment, SPT N-values below 10 in saturated fine sands require mandatory liquefaction screening per ASCE 7-22 Section 11.8.
