Implementation of In Situ Activated Carbon
Remedies at Contaminated Sediment Sites

MONITORING

FRICTION SOUND PROBE

The sediment friction-sound-probe (SED-FSP) tool is used to provide direct, in-situ measures of in the field of the horizontal and vertical extent of grain size. Developed by US Navy scientists under SERDP Project ER-200919, this tool is especially effective for conformational sampling for placement and long-term resiliency of AC remedies that include a sand cover, or for other remedies such as Enhanced Monitored Natural Recovery or conventional sand covers.

The SED-FSP technology was developed based on the well-established principle that the friction-sound intensity at a particle/sensor interface is a linear function of the radius of particles in contact with the sensor surface and the velocity of the probe. SED-FSP employs this relationship to infer grain size by measuring the acoustic response as a probe with an imbedded microphone penetrates a sediment matrix.

The microphone signal is processed through an on-board electronics interface package and transmitted to recording software. A pneumatic drive unit mounted on an aluminum frame assembly is used to drive the probe into the sediment bed at a controlled speed. Grain size is determined by comparing the acoustic response to responses of prepared sediments of known grain sizes, the calibrations are performed prior to the field deployment.



SED-FSP was demonstrated as part of the ER-200919 project at the Active Capping Pilot Study Site on the Anacostia River in Washington DC. That cap, first installed in March 2004, included a sand cover and SED-FSP was used to demonstrate the capability of the SED-FSP to acquire grain size measurements in subsurface sediments, to delineate the capping material/native sediment interface, and to provide information on the capping thickness. Of the 44 core sections submitted for validation, the SED-FSP correctly predicted 42 size classification results. The SED-FSP identified the subsurface capping material/sediment interface and confirmed that its thickness and boundaries have remained intact. This was confirmed with the sediment cores, which showed that the capping material remained intact with little dispersion beyond the cap boundaries or into the underlying native sediment.

SED-FSP was employed as a post-placement and long term monitoring tool for an EMNR site at Quantico, and is reported in ESTCP project ER-201368. Used in conjunction with sediment coring and Sediment Profile Imaging, SED-FSP was effective in delineating the placed cover material from native sediments, and confirmed the aerial extent and depth of the sand during subsequent monitoring events.

SED-FSP was tested as part of an in-lab treatability study to determine the ability to detect placed AC as AquaBlock® prior to field demonstration at the Puget Sound Naval Shipyard. The Treatability Study results, which are presented in the Case Study for the PSNS project, was also able to distinguish between unamended and amended sediment layers. SED-FSP, coupled with the SPI camera and core samples was important in verifying placement, stability and mixing of amendment post-placement.  

The sediment friction-sound-probe (SED-FSP) tool is used to provide direct, in-situ measures of in the field of horizontal and vertical extent of grain size.

The microphone signal is processed through an on-board electronics interface package and transmitted to recording software. A pneumatic drive unit mounted on an aluminum frame assembly is used to drive the probe into the sediment bed at a controlled speed. Grain size is determined by comparing the acoustic response to responses of prepared sediments of known grain sizes, the calibrations are performed prior to the field deployment.”

SED-FSP profiles from the ER-201368 post-placement monitoring at the Quantico Enhanced Monitored Natural Recovery project. Blue lines and diamonds are the SED-FSP data; orange square symbols (and green for one station duplicate) are measured grain size D50s from the cores collected at these stations. Blue colors indicate native material, green tones indicated mixed zones, and yellow color indicates predominate sand.

Additional Resources

Demonstration of an In-Situ Friction-Sound Probe for Mapping Particle Size at Contaminated Sediment Sites. SERDP/ESTCP ER-200919 project web page, including the Final Report.

Demonstration of an In-Situ Friction-Sound Probe for Mapping Particle Size at Contaminated Sediment Sites. SPAWAR Systems Center Pacific. Technical Report 2040. April, 2014.

Demonstration and Validation of Enhanced Monitored Natural Recovery at Department of Defense Sediment Sites. SERDP-ESTCP ER-201368 project web page, including the Final Report.

New Tools for Improving the Management of Contaminated Sediment Sites
Webinar presented by Dr. Philip Gschwend, Massachusetts Institute of Technology, and Dr. Bart Chadwick, SPAWAR Systems Center Pacific. Presented November 20, 2014 – Webinar Slides