Image depicting cone penetrometer testing methodology. Sensors (Type 2 piezocone, pictured LEFT) measure the axial force on the cone, the upward friction, and the inward pore pressure to determine soil behavior which is interpreted (RIGHT) during cone advancement. (Credit: Courtesy of Hazen, T., et al., Effects of Cone Penetrometer Testing on Shallow Hydrogeology at a Contaminated Site, 2022, https://doi.org/10.3389/fenvs.2021.821882.)

The Science

Cone penetration testing, which consists of pushing an instrumental cone into the ground at a controlled rate and quantifying the resistance from the surrounding soil, is a widely-used, efficient method for mapping features below the earths’ surface to determine key soil characteristics or contaminants. While the small footprint and reproducibility of cone penetrometer testing makes it well-suited for collecting samples at contaminated sites, the effects to the local environment and groundwater wells are relatively unknown. In this study, ENIGMA researchers measured physical and geochemical effects of cone penetrometer testing on nearby shallow groundwater wells. They found that the effects of cone penetration on water level and conductivity were minimal, and that subsequent precipitation at the site caused a greater disturbance to the groundwater than any cone penetration testing.

The Impact

Results from the study indicate that cone penetration testing is a viable method for field sampling in that it causes relatively minimal impacts to surrounding groundwater.

Summary

Researchers found that the effects of cone penetration were only identifiable within the disturbed area and were similar in magnitude to the effects of local low-flow pumping. Subsequent precipitation had a significantly higher impact on the variability of groundwater geochemistry and water level than any penetration. They also found that at this site, water displacement during penetration was highest in material where fractures and macropores had formed from the dissolution of material by low-pH groundwater. This may indicate that although the effects of cone penetration testing on nearby groundwater are generally minimal, site-specific criteria should still be taken into account.

Contact

Terry Hazen, Subsurface Observatory Science Lead
University of Tennessee
tchazen@utk.edu
(707) 631-6763

Publications

Putt, A. D.; E. R. Kelly, K. A. Lowe, M. Rodriquez Jr., and T. C. Hazen. “Effects of Cone Penetrometer Testing on Shallow Hydrogeology at a Contaminated Site” Frontiers in Environmental Sciences. 9, (2022) [DOI]:10.3389/fenvs.2021.821882 OSTI:1839769