The SPT hammer drops 30 inches onto the anvil, driving the split-spoon sampler 18 inches into the subsurface. That blow count — recorded every six inches — is the first data point we need for liquefaction analysis in Newark. The city sits on unconsolidated Quaternary sediments, with a shallow water table barely 5 to 8 feet below grade in much of the Ironbound and along the Passaic River. We process those field numbers through cyclic stress ratio calculations back at our AASHTO-accredited lab, correlating corrected N-values with fines content from wash sieving. A single boring can reveal whether saturated loose sands will fluidize during a design-level earthquake. For deeper profiling where SPT refusal occurs, we often pair the fieldwork with a CPT test to capture continuous tip resistance and pore pressure data through interbedded silts and clays.
In Newark, liquefaction isn't theoretical — it's a shallow-hazard problem where the water table meets loose hydraulic fill within the first 15 feet.
