[CPEO-MEF] Underwater OE detection

[Lenny Siegel <lsiegel@cpeo.org>]

Over the past several years, the U.S. military, its contractors, and
regulatory agencies have made slow but steady progress in understanding
how to find ordnance buried beneath the surface of the land. However,
little has been done to address ordnance found under water, either on
the surface of underwater sediment , or buried beneath the surface of
that sediment.

On the positive side, the Navy (Pacific Division, Naval Facilities
Engineering Command) sponsored a field test of ordnance detection
systems at Mare Island Naval Shipyard (MINS), in Vallejo, California.
The Validation of Detection Systems (VDS) was conducted by Environmental
Chemical Corporation (ECC), of Burlingame, California. Its July, 2000
Final Report provides valuable information that should lead to practical
programs of underwater ordnance detection and removal, at Mare Island
and elsewhere.

Mare Island is closing military industrial facility northeast of San
Francisco. The Navy has identified three onshore and four offshore sites
that potentially contain ordnance and explosives (OE). The facility
never contained a high explosive range, so the ordnance found there is
believed to result primarily from discarding or disposal.

The report explains, "The primary objective of the VDS Test Program was
to identify, select, and validate detection equipment and technologies
that could be used to locate and detect OE at the four offshore sites at
MINS." The program also sought a minimum of 85% probability of
detection, and it hoped to demonstrate the ability to use sensors to
acquire digital data that could be used to for post-processing and the
re-acquisition of targets.

ECC identified a test site on the tidelands at the southeastern tip of
the island. At low tide, it cleared metallic debris - there was no
ordnance found - from the sediment surface. It seeded a
3750-square-meter Test Area with mock ordnance and debris, and it
selected five teams of technology experts/vendors to characterize the
site. It also seeded a 300-square-meter Reference Area so technology
developers could test and calibrate their equipment.

Each team was given up to 20 hours over a three-day period to
demonstrate their equipment. Unlike ECC, they worked when the tide was
in. That is, the site was beneath two to six feet of water. Some of the
teams had equipment trouble or difficulty managing the boats they used
to tow their equipment. But overall the test did a good job of measuring
the competence of the teams and the suitability of their equipment.

Only one participant, NAEVA Geophysics of Charlottesville, Virginia,
exceeded the 85% detection goal, and it achieved an impressive 99%, a
detection rate that would be impressive on dry land. Moreover, its
method appeared to screen out interference from a simulated metal pier,
placed along one edge of the Test Area. NAEVA used a waterproof version
of the Geonics EM-61 electromagnetic induction device. Since NAEVA was
the only participant to tow its instrument on an underwater sled, the
test appears to have demonstrated the superiority of that approach over
the flotation of instruments, used by the other four teams.

A second participant, Geophex Ltd. of Raleigh, North Carolina, also
scored well. It achieved an 84% detection rate, but it outscored NAEVA
on a number of other criteria, including reducing false alarms, accuracy
of detection, and ability to handle simulated ordnance clusters . It
used a combination of four Geometrics G-858 Cesium Vapor magnetometers
and its own GEM-3 electromagnetic sensor. Geophex appeared to have more
experience than the other teams in processing the data generated by its sensors.

The VDS test program achieved its objectives, with accurate digital
recording demonstrated by most teams. However, like most successful
research programs, it raised additional questions. Here are my top two:

First, should the Navy (or any other responsible party at an ordnance
site) simply select the "winner" of a field test? Or should it design a
cleanup that combines the qualifications of more than one team. My
reading of the final report suggests that Geophex's instruments and
processing skills would achieve maximum success on NAEVA's underwater sled.

Second, how does one determine the "winner" when there are multiple
criteria, and who determines which criteria are most important? NAEVA
easily outscored the other participants in achieving a near-perfect
probability of detection, but Geophex scored well on technical criteria
designed to reflect the need to hold down costs. My guess is that the
people who expect to live, work, and recreate near such underwater
ordnance sites would prefer certainty over frugality, but a
cost-effective solution would make it possible to address more sites or
more area with the same funding.

One thing is clear, with a growing number of near-shore ordnance sites
potentially requiring cleanup, the Navy needs to organize more such
tests. And it should be given credit for this one.

(The Navy contact for this project is Patricia McFadden, <McFaddenPA@efdsw.navfac.navy.mil>.)

LS

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Lenny Siegel
Director, Center for Public Environmental Oversight
c/o PSC, 278-A Hope St., Mountain View, CA 94041
Voice: 650/961-8918 or 650/969-1545
Fax: 650/961-8918
<lsiegel@cpeo.org>
http://www.cpeo.org

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