INPEX Catalina Darwin
INPEX Operations Australia Pty Ltd
Cosmos Archaeology was tasked with analysing the potential impacts of dredging works on six WWII-era PBY Catalina aircraft wrecks, located at East Arm in Darwin Harbour. A portion of East Arm had been earmarked for dredging as part of the INPEX Ichthys Project to create a new shipping channel, turning basin and berthing area.
Though the wrecks were beyond the dredging footprint, potential threats were identified, including inadvertent direct interaction with project vessels and deleterious impacts arising from excessive sedimentation, erosion and scouring.
Due to the cultural heritage significance of the sites, a monitoring programme was established, to detect any changes to the wreck sites before, during and after the dredging works. The monitoring was undertaken by Cosmos Archaeology’s skilled maritime archaeologists and included diving inspections and pedestrian surveys at low tide. Archaeologists recorded sand levels at established datums around the wrecks and took video and still imagery when conditions allowed. The archaeologists’ observations of the condition of the wrecks was also an important component of the monitoring. When available, multi-beam sonar data was also used to supplement interpretations of changes and/or the stability of the sites. A range of management responses were available for implementation if any of the threshold limits were exceeded. During the 33 monitoring inspections, archaeologists also updated the site plans for each of the wrecks.
The threshold limits for deteriorating marine growth, sedimentation, sediment loss and scouring were not exceeded for any of the six Catalina wrecks, so no mitigation response was required.