ESTCP-funded researchers at Pacific Northwest National Laboratory (PNNL) designed an underwater unexploded ordnance (UXO) test bed site for technology demonstrators to test and operate detection, classification, and geolocalization technologies.
By Dana E. Fahey
Many sites worldwide contain munitions or unexploded ordnance (UXO). These are the lasting result of military conflicts or use on firing ranges or installations that are now closed. While many land sites have been successfully remediated with advanced technologies, over 400 underwater sites have been identified as potentially impacted by UXO, making underwater munitions response a critical priority for the Department of Defense (DoD).
Figure 1. Examples of inert UXO (PNNL photo by Shanon Dell)
There are many added challenges compared to land sites, e.g., the unpredictable effects of water on explosives and the need for advanced technology and skilled dive personnel.
“One of the biggest problems is the question of where these [UXO] are located. It’s the unknown; and the ability to detect them is key,” shared PNNL’s Dr. Dana Woodruff, coastal marine scientist and Principal Investigator (PI) with the Strategic Environmental Research and Development Program (SERDP) and the Environmental Security Technology Certification Program (ESTCP).
The SERDP and ESTCP program office determined the first step to illuminating these unknowns was establishing standardized test bed sites, demonstration sites where they could evaluate the performance of technologies that detect, classify, and locate (DCL) the underwater UXO. The ESTCP program office then put out a call for proposals to establish underwater test beds, and Dr. Woodruff and her team responded.
SERDP and ESTCP hosted an underwater test bed workshop, and researchers determined that underwater test beds would need to geolocate munitions within one meter accuracy, so that divers can relocate the ordnance quickly, even with poor visibility underwater.
“Early on, most everyone said, ‘no way, you can’t do that in deep water,’” said Dr. Woodruff. On land, a GPS antenna can locate UXO within 1- to 2- centimeters, but working underwater is far more difficult. However, Dr. Woodruff and her team were ready—and excited—to respond to that challenge.
Figure 2. PNNL Marine and Coastal Research Laboratory staff project staff on the ESTCP underwater test bed in Sequim Bay (PNNL photo by Shanon Dell)
Drs. Dana Woodruff (PI) and Joe Haxel (Co-PI) at Pacific Northwest National Laboratory (PNNL) have since been ardently working to advance research on underwater UXO response efforts. Under Dr. Woodruff’s previous SERDP project, Sequim Bay in Washington was identified, evaluated, characterized, and designed as a test site for UXO detection technologies. The second phase was then a prototype demonstration, in which strengths were identified and weaknesses corrected. The resulting test design informed by this SERDP project led to the ESTCP project (phase III of the overall effort), wherein the operational test bed is used to support the evaluation of underwater UXO DCL technologies.
The PNNL team was one of the first to establish an operational deep water test bed, where performers could test their technology. It is important for munitions detection technologies to be tested at different types of sites (e.g., shallow, deep, clear water, opaque water) to assess technology performance across environmental conditions and various coastal settings where UXO may be found (e.g., beaches, harbors, tidal estuaries). The team selected Sequim Bay as the location for the test bed for a couple of reasons, including its proximity to Seattle, PNNL’s Marine and Coastal Research Laboratory (MCRL), and a nearby marina. Sequim Bay also “has various types of sediment and substrates, which is advantageous to the program and demonstrators when looking at how technology performance varies with sediment type,” shared Dr. Haxel. Since the Sequim Bay test bed is a large, deeper water site, it is optimal for autonomous and towed systems, providing ample space for operating these technologies that require more room and a significant turning radius for making a series of passes over the test bed areas.
To gauge UXO recovery, the team conducts regular support activities for the developers who are demonstrating technologies at the test bed, including collecting daily water quality and underwater sound speed profiles. This allows the developers to focus solely on their technology.
“Our team is always outside—we're diving, using boats, on the water a lot. An advantage of having the test bed right outside the lab door is the easy access. We can get out there and do things within a short amount of time,” Dr. Haxel shared.
Figure 3. PNNL research divers John Vavrinec and Sue Southard prepare for target placement and data collection in Sequim Bay (PNNL photo by Noelani Boise)
A skilled scientific dive team places the targets in the preplanned locations and relays multifaceted information about the object’s position and orientation on the sea floor using an acoustic system and under water diver communications. They provide the program office data on the location, type, and number of targets to aid in the performance assessment of the technology.
“The key is the detection and geolocation of targets of interest,” said Dr. Haxel. “The pieces of information that we provide are the geolocated position of the target with sub meter accuracy; how it's oriented on the seafloor; and other additional information with regards to burial, or if seaweed and algae has clumped on it. Those types of things may be of interest during the scoring or evaluations of the technologies.”
Detecting and geolocating objects underwater is a challenge. The PNNL team uses an acoustic system that allows them to get a 3D position of an object with submeter accuracy. They then use the data points to map the geolocated targets and an independent scoring team can then determine the extent to which a technology demonstrator’s detection points deviate from the PNNL-derived groundtruth data points.
This allows the program office to compare the strengths and weaknesses of each technology.
The first team that the PNNL team collaborated with at the test bed was from University of Washington’s Applied Physics Lab (UW-APL). The UW-APL team brought their Multi-Sensor Tow Body (MuST) system, an acoustic-based system, which Dr. Haxel explained is “towed behind the vessel and uses several different types of acoustic technologies that can penetrate the sea floor, as well as detect and classify UXO with a sophisticated approach.” The UW-APL MuST team was critical in getting the test bed from a prototype demonstration to an operational stage.
Underwater test sites like Sequim Bay are critical for testing, improving, and iterating on UXO DCL technologies to move them towards operational status. Test beds significantly speed up the process of demonstrating technologies, as researchers are freed up from logistical design and implementation of individual test sites for each technology, and able to focus on the technology’s development and performance. As test beds have helped fill critical data gaps and accelerate technology refinement, munitions response projects are now shifting to focus on transition to the user community through controlled site demonstrations and live site operations under ESTCP.
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About SERDP & ESTCP
The Strategic Environmental Research and Development Program (SERDP) and the Environmental Security Technology Certification Program (ESTCP) harness the latest science and technology to improve the Department of Defense’s environmental performance, reduce costs, and enhance and sustain mission capabilities. The programs respond to energy and environmental technology requirements across the military services. SERDP and ESTCP are independent DoD programs managed jointly to coordinate the full spectrum of research and development efforts, from the laboratory to field demonstration and validation. For more information, visit https://serdp-estcp.mil. Follow us on Twitter, Facebook, and LinkedIn.
