CPT/ROST™

The Cone Penetration Testing/Rapid Optical Screening Tool (CPT/ROST™) application represents an efficient application that combines in-situ geologic and real-time hydrocarbon screening data to evaluate the presence and distribution of light non-aqueous phase liquid (LNAPL) in the stratigraphic environment. The CPT characterizes the stratigraphy while ROST™ identifies the presence of hydrocarbons. This technology application is well-suited for sites with complex stratigraphy and multiple hydrocarbon sources and types.

CPT consists of a cone with strain gauges mounted on a probe that is advanced hydraulically through the soil column. The strain gauges measure physical soil properties to produce a continuous, real-time stratigraphic record of the boring. The ROST™ uses an ultraviolet wavelength laser source with an optical detector to measure fluorescence response to polycyclic aromatic hydrocarbon (PAH) compounds present in the soil matrix as the probe is advanced. The fluorescence response is measured simultaneously at each of the monitoring wavelengths (340, 390, 440, and 490 nanometers) that cover the range of fluorescence produced from short chain hydrocarbons (shorter wavelengths) to long-chain hydrocarbons (longer wavelengths). The relative percentage of fluorescence response at each of the four wavelengths is measured and plotted continuously on the ROST™ logs as four color bands.

SMA begins CPT/ROST™ investigations by advancing borings adjacent to monitoring wells containing LNAPL to develop a correlation between the ROST™ results and the presence of mobile LNAPL. Upon completion of the investigation, SMA makes interpretations regarding extent of mobile LNAPL (LNAPL that can accumulate in a monitoring well) versus residual LNAPL based on correlation with wells containing LNAPL, the fluorescence response intensity, and the vertical extent of the response represented on the ROST™ log. SMA also utilizes various software programs to integrate the CPT/ROST™ investigation data into cross sections and 3D maps to visualize the relationship between stratigraphy and LNAPL.