Some of the concrete facilities resting on the seabed on the Norwegian shelf are nearing the end of their lifetimes. In the coming years, the authorities need to address how to dispose of these.
A report has been prepared on disposal of concrete facilities on initiative from the Norwegian Petroleum Directorate (NPD), which invited the Petroleum Safety Authority Norway (PSA) and the Climate and Pollution Agency (Klif) to delve deeper into the agencies’ respective disciplines.
“In the new study we’ve looked at different technological solutions for disposal of the concrete facilities, and assessed these in relation to health, safety and the environment. The report will be included in the background material for assessment of future disposal solutions,” says Arne Holhjem, director for technology and the environment in the NPD, director for professional competence Øyvind Tuntland in the PSA and Signe Nåmdal, head of department in Klif.
The Convention for the protection of the marine environment of the North East Atlantic (OSPAR), stipulates joint provisions and recommendations for offshore petroleum activities. Pursuant to OSPAR decision 98/3 relating to disposal of disused offshore installations, all facilities must in principle be removed. As regards concrete facilities, licensees can apply for an exemption from the ban on disposal at sea.
There is little experience from removal and scrapping of concrete facilities, and little data to base analyses on. The assessment by the NPD, PSA and Klif shows that, although some facilities have installed equipment that enables them to float again (re-floating), there are many uncertainties as regards whether such operations can be implemented in a controlled manner.
The advantage of disposal on land will primarily be that the reinforcement rods, and possibly the concrete, can be recycled and the seabed can be returned to its natural condition. An alternative to scrapping and material recycling could be using all or parts of the facility, e.g. as bridge foundations or to create artificial land.
Removing facilities is not risk-free. In a worst case, an accident during preparation, re-floating, transport or scrapping could have serious consequences such as loss of life or negative environmental impact. Landing the concrete facilities for scrapping and material recycling could result in risk of discharges to sea and demolition operations on land will result in noise and dust. Available area, both onshore and offshore is required, and conflicts with the local environment can arise.
Abandoning concrete facilities on site is an alternative to landing, which can also have advantages as regards safety and be environmentally acceptable. Abandonment will have little impact on fish populations, but might conflict with fishery interests due to tied-up area. Lights and navigation equipment must be installed on abandoned facilities; the risk of conflicts with ship traffic will then be relatively small.
Source: NPD, March 21, 2012