Oslo’s big cleanup
Despite the apparently pristine surface of Oslo Harbour, “we don’t know yet what’s really under the water,” said the port’s chief engineer Edvin Kongsten Wibetoe.
There may well be decades of detritus, he explained, as attitudes have changed dramatically: “I’ve seen newspaper ‘advice’ written in the 50s which said, ‘if you want to get rid of your car, just drive it out onto the ice over a deep spot in the Hornindalsvatnet lake and watch it disappear’... It was ‘out of sight, out of mind.
Therefore the harbour authority has purchased a small, portable Deep Trekker mini-ROV which gives the harbour authority “a fish-eye view of the problems” said Wibetoe. Usefully, the DTG2 is easy to manoeuvre as its outer shell and thrusters rotate while gravity keeps the frame in position, allowing 3D motion while keeping the cameras stable.
The initial scan uncovered quantities of trash: fishing gear, cage traps, rubber gloves, tires, bikes, miscellaneous bits of steel “and a moped”, he explained. This was followed up by an intensive, four-hour clearing session by volunteers from the Indre Oslofjord dive club, the Dykkerforbundet (national diving association) together with the Marinereperatørene, a professional organisation.
“A government fund is supporting volunteering clubs with money for extra tanks and so on,” said Wibetoe, but he added since the harbour settlement had existed for millennia, there’s also the potential for turning up valuable, historical artefacts.
However, while this operation focused on the 100m of seabed directly in front of the quay, he expects to find other patches where rubbish has accumulated after being picked up by the current: “We also know that in certain areas smaller vessels like fishing boats have been disposed of by sinking,” he said, and added that hired help might well be necessary for shifting larger objects.
On top of it all, there’s still today’s rubbish to deal with. Along with self-compacting landside litter receptacles, the harbour has a marine ‘bin’ which passively traps flotsam and retains it for pickup. “The Portbin works well, but it needs emptying every day and we don’t always have the resources for that,” said Wibetoe. Therefore the authority is collaborating with manufacturer Spilltech on a bigger, 1m3 capacity version which should hold a week’s worth of refuse.
By Stevie Knight
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