Mar 18, 2017

Pilot Project Evaluated Three Different Geophysical Instruments

In November, our team completed the Pilot Project at three selected residential properties.  The collected data is currently being used to evaluate the suitability of using two newly developed “Advanced Classification” geophysical instruments [the Time domain Electromagnetic Multi-sensor Towed Array Detection System (TEMTADS) and Man Portable Vector (MPV)] within the Spring Valley residential area to detect and correctly identify buried munitions and explosives of concern related items during upcoming cleanup activities outlined in Site-Wide Decision Document being finalized ... For the purposes of the Pilot Project, all detected anomalies were intrusively investigated (dug up and removed from the ground).  About 200 anomalies on average were removed from each property.  The purpose of this effort was to verify if the new instruments were characterizing the anomalies correctly.  The majority of the items were innocuous non-military related cultural debris, such as nails, wire, bottle caps, and wire baskets.  Four pieces of munitions debris were also removed from the site: three fragments of munitions debris and one three inch Stokes mortar, which was determined to be an unfused practice round and did not contain any explosive or chemicals.  The TEMTADS and MPV both identified the Stokes mortar correctly.
Spring Valley USACE
The Corps'pondent
February 2017 (pg. 2)
[Project Manager Dan] Noble added that what is also interesting about the new technology is that it is the same technology as the EM-61 instrument that missed the target in previous investigations ... because the target was too close to the house.  These new instruments, because they are very focused on the ground immediately underneath the instruments, have very good resolution for what is directly underneath them.  The new instruments were able to clearly see that there was an anomalous area using the exact same EM (electromagnetic) technology that formerly was blind in the same area ... The previous instrument was the size of a lawnmower and recorded GPS coordinates of targets for later review.  The new technique includes the same dynamic scan, and when a target is located the team will go back and perform a cued investigation.  The cued investigation is the second part of the survey in which the instrument is parked directly over the target for approximately 30 to 60 seconds.  A tremendous amount of data calculations are created concerning decay constants of the target.  This allows the precision of location and identification of the target, leading to a better excavation decision.
Restoration Advisory Board
Meeting Minutes
January 10, 2017 (pg. 6)

The summary of the Pilot Project results did confirm that Advanced Geophysical Classification (AGC) is more effective at munitions detection than the current conventional EM-61 digital geophysical mapping methods used, but that there were some challenges.  It was also concluded that AGC should be used with the G-858 magnetometer in order to detect large items at deeper depths.  The report concluded that TEMTADS and the MPV each have their own advantages and disadvantages, but that either instrument could be efficiently used for the full scale munitions remediation throughout Spring Valley.  The AGC method would provide the highest level of confidence in the geophysical surveys.  USACE expects the AGC method will provide less anomaly investigation throughout the remedial action for the Spring Valley FUDS.
Spring Valley FUDS Partners
Meeting Minutes
February 9, 2017 (pg. 4)

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