Christwigg wrote ;
"Marine Minerals Limited is yet to announce the method of dredging they will use to remove tens of millions of tonnes of sediment from the North Cornish coast......"
In 1976 Marine Mining ( Apparently the previous name of the present company) did some sampling tests and they used 'Quote' - ".....a suction dredger to obtain two bulk samples of several hundred tonnes each......"
The flow rate into the dredger from the sea bed was 35 cubic metres per minute ( 😮 ) or 8000 gallons per minute, with screening to desired sizes on-board ship. The ship in this case had a hold capable of carrying 500 tonnes of sand.
All the waste water and oversized material was sent over the side of the ship, and the cargo drained through a layer of coir for the bilge pumps to take away.
The oversize spillway was sampled at regular intervals too, and most of the material consisted of coarse shell fragments and very occasionally large fragments of rock.
Not wanting to step into any particular camp here :flowers: , I do wonder what effect this will have on the local sealife in the area. The sand on the seabed plays an important role in the water cycle, treating waste materials and dealing with the Nitrogen/Ammonia cycle which is critical to good water purity for all sealife. Disturbing this substrate churns up tons of anaerobic bacteria which is deleterious to sealife.
Curiously (?) I haven't seen any reports contained within dredging proposals, that deal with this aspect.
Anyone who has kept a marine aquarium will be familiar with the importance of this.
"You Chinese think of everything!"
"But I''m not Chinese!"
"Then you must have forgotten something!"