[Herman Melville]

Possibly another stupid question, but can landfill be used to combat rising sea levels? Can sea walls, coastal fortifications and so on be constructed out of compacted waste in a way that would effectively kill two birds (rubbish disposal, rising sea waters) with one stone?

[Mazurka]

There are techniques such as baling of waste tyres that could provide useful blocks for engineering works, but there are a number of problems with using general mixed waste for such a purpose.

URRO (Used Rubber Recycling Operations) blocks  made from baling approximately 100 tyres into a block approx .5 x.5 x1 m have been successfully used to replace conventional materials in road construction and landfill lining operations. More information at http://www.northerntyre.com/

As waste rots down so does it volume - which makes it unstable thus unsuitable for engineering works.  Also in an erosive situaiton, the waste that does not break down such as some plastics, glass etc, would get washed out.  Certainly in the UK, the specification of landfil linning systems required throught the environmental permitting regime adminstered by the Environment Agency would not allow this use for general waste.  It would also be harder to install landfill gas and leachate management systems to control pollution if there is a risk that the lining will become damaged and air/ seawater get in.   There is an old landfill site on Walney Island which was the focus of costal defence works to prevent the site from being washed away into the Irish Sea!   

Where land reclamation schemes have involved significant "landfill" it has typically been inert and/ or mining waste such as earth and rock.  Samphire Hoe in Kent is an example of this - where some fo the muck from the channel tunnel was disposed of and the newly created land turned into a nature reserve.

[Herman Melville]

Thanks, Mazurka. The Samphire Hoe site is quite interesting: http://www.samphirehoe.com/creation.asp