Underwater MEC Technology and Investigation
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Underwater MEC Technology and Investigation Bryan Harre Naval Facilities Engineering & Expeditionary Warfare Center Topic Outline . Provide short background on policy for inclusion of underwater munitions and explosives of concern (MEC) and munitions constituents (MC) sites into the Navy’s Munitions Response Program (MRP) . Describe the current status of the Navy MRP and the number of underwater sites identified to date . Discuss some of the technologies that are currently available to investigate an underwater munitions response site 2 Navy Underwater MRP Site Policy . Shallow water areas where munitions relkleases are known or suspec tdthted to have occurred and where: • Navy actions are responsible for the release • Munitions in <120 ft of water ♦ Munitions in waters between high and low tides will be considered terrestrial Scuba diving experience and training class. Photo courtesy of US Navy. 3 UW Sites per Facilities Engineering Command . 57 Underwater Sites (includes both ERN and BRAC sites) • NAVFAC Washington – 17 • NAVFAC Mid-Lant – 14 • NAVFAC Southeast – 5 • NAVFAC Midwest – 2 • NAVFAC Southwest – 8 • NAVFAC Nor thwes t – 8 • NAVFAC Pacific – 2 • NAVFAC Lant – 1 . Additional Underwater Sites (not part of the MRP) The Navy performs dredging for new construction and to maintain waterwayyys around Navy installations but aren’t part of the MRP 4 Underwater MRS Characteristics . Before you investigate, know your site ’s envi ronment • Ocean, bay, river, lake, island • Depth, currents, wave action, tides, water clarity, turbulence • Local weather • Bottoms (soft, hard, sediments) • Habitat (sea grass beds, coral reefs, open bottom, swamps, marshes) • Inhabiting biota (especially T&E UXO laying proud on rock species) bottom. Photo courtesy of US Navy. 5 Underwater CSM 6 Survey Design and Rationale (1) . Transect survey • Oriented perpendicular to long axis of AOPC to maximize chances of defining area • Best implemented at sites with easy topography/terrain and minimal obstacles/ vegetation • Follow semi-fixed path with start/end points . Potential mobility of items must be considered in design and timing of investigation • BdCSMitditiBased on CSM, site conditions, and investigation objective 7 Survey Design and Rationale (2) . Transect spacing must ensure proper site character- ization to determine nature and extent of MEC contamination Graphic courtesy of US Navy. 8 Detection Technologies . Depth drives selection of right technology • Sonar – map the bottom • Visual/laser line scanner • Magnetometer/ EMI – detect and map ferrous/metallic anomalies • Platforms – diver, ROV, AUV, surface vessels 9 Multi-beam Sonar (1) Simplistic view of multi-beam sonar Graphics courtesy of US Navy. 10 Side-scan Sonar (1) Graphics courtesy of US Navy and NOAA. 11 Imaging Sonar (1) Contact and Manta mines. Photo courtesy of US Navy. Hand-held imaging sonar with diver mask display. Photos courtesy of Sound Metrics. Hand-held sonar image of Cone mine. Video courtesy of Sound Metrics. 12 Array Length Determines Resolution of the System . “Aperture” = “length of sonar array” . Beam Width ~ Acoustic wavelength/aperture . Resolution of single-ping sidescan sonars degrades with range For side-looking sonar effective pixel size increases with range . Longer arrays provide finer spatial resolution, however handling and cost considerations limit arrays to ~10 feet 13 Multi-Ping SAS Processing Produces Range- indepp,gendent, High-resolution Seafloor Images SLS image Close-up of signal history aperture locations data samples (constant phase arc) SAS image 14 Small Synthetic Aperture Minehunter II SSAMII sonar capabilities snapshot : REMUS600 UUV capabilities snapshot: • The SSAM II sensor concept employs multiple • Navigation: GPS, 1.2 MHz DVL, Kearfott T-24 IMU simultaneous transmitters (HF and BBLF) and • RF communication: Wi-Fi and Iridium BroadBand (BB) hydrophone arrays to combine high- • Acoustic communication: WHOI μModem, tracker resolution imagery and acoustic target scattering over • Energy: 5.4 kWh rechargeable Lithium ion battery pack. a wide range of frequencies for improved detection • Frontal fins for improved stability and control. and classification of underwater proud and buried targets. Overall system characteristics: • Utilizes Synthetic Aperture imaging techniques to • Length: 14 feet Weight: ~ 675 lbs generate imagery of constant cross-range resolution. • Endurance: ~10 hours Nominal speed: ~ 3 knots • Design supports: • Maximum operational depth: 600 feet – HF bathymetry estimation • Area coverage rate: ~ 0.19 square nautical miles per hour – Multi aspect imaging • Deployed/recovered from small boat, ship or pier using – Closed synthetic aperture sonar imaging for near crane or ramp ID quality acoustic imagery. 15 SSAMII Sample Images Examples of subsurface imaging HF bathymetry 16 MEC Detection/Mag and EMI . Magnetometers and EMI • TdTowed arrays ESTCP- sponsored • Hand-held demonstration of SAIC’s instru me nts undtderwater multiple-towed • Sled mounted array. Photo systems courtesy of ITRC. • Aerial systems Surface towed EMI system. Photo courtesy of US Navy. 17 Hand-held Systems Photos courtesy of US Navy and US Army. 18 REMUS 600 Buried Mine Identification (BMI) System Photo courtes y of US Navy. Length = 168” Mission Speed = 3 kts (vehicle rated up to 5 kts) Diameter = 12.75” Endurance = 12 Hours at 3 knots Weight Dry = 660 lbs Max Depth = 90 m with LSG in composite paylldoad (ve hic le rate d to 600 meters ) This system can be launched/recovered from small boat, ship or pier using crane or ramp 19 19 Platforms . In order to make measurements to determine whthhether th ere i s MEC or not , some t ype of platform must be used • Man-portable • ROVs • AUVs • ASVs • Vessels with or without towed systems Diver performing seafloor search Photo courtesy of US Navy. 20 Diver Search/Survey Methods . Jackstay method • Stationary • Walking . Circ le-line search meth od Diver swims down lower right buoy line, then swims to opposite buoy line along Diver swims down a search line, looking 2 ft buoy line and ties either side. Diver then off knotted line to moves the line (stationary clump. Diver methd)hod) or th e b uoy cl ump swims in a circle (walking method) 4-5 ft, holding each then swims back to first succeeding knot buoy line, repositions, and until reaching end repeats process. of search line. 21 ROVs and Crawlers . ROVs are typically controlled and powered fthfbtthdlifrom the surface by an tethered line • Micro, mini and work-class ROVs • Sonar, magnetometer and video equipped • Some with manipulator arms VideoRay ROV. Photo Manipu lato r ROV. courtesy of US Navy. Photo courtesy of US Navy's ROV "Deep WHOI TV. Drone“ recovers a piece of Alaska Air Flight 261. Photo courtesy of US Navy. 22 AUVs (1) . AUVs can be thought of as robotic submarines and can carry a wide array of payloads • Fly-by data collection using depth sensors, sonars, magnetometers, thermistors, ONR’s X-Ray underwater glider. and chemical sensors Photo courtesy of US Navy. • Range in size from cm to m • Powered by rechargeable batteries • Ultra low power gliders being developed AUV mine clearing in Iraq. Photo courtesy of US Navy. 23 Vessels (1) Graphic courtesy of US Navy. 24 MEC Evaluation/Recovery . Some type of evaluation and/or recovery thltechnology of fMECldb MEC could be empl oyed • Divers • Lift b ags/b ask et s • Robotics/ROVs • Magnetic lift systems • Dredging and screening Graphics and photo courtesy of US Navy, ESTCP, and Subsalve. 25 25 ROVs Step 1 - Spot Basket Step 2 - Load Step 3 - Transfer ROUMRS used at Ordnance Reef, HI. Step 4 – Recovery Rigging Step 5 – Tow to demil barge. Treatment/Bubble Curtain . Bubble curtains are mitigation technology to augment MEC treatment by BIP . Bubble curtains are designed to reduce pressure waves and noise from MEC BIPs to protect marine life . Bubble curtains required by National Marine Fisheries Service (NMFS) to mitigate offshore oil pla tform demoliti ons and underwater pile driving . Navy’s SPAWAR has developed a successful R&D prototype for Graphic courtesy of ESTCP. large MEC 27.