Swansea Bay, tarmac and sand dredging

Today was brisk, or bracing if you prefer. Mrs D and I took a walk between Swansea and Mumbles, dodging the showers. We ate a bargain lunch for two in Mumbles for £6.95! Not surprisingly the other clientele were of similar vintage and it was rather like an old folks home with walking sticks and zimmers galore. But the lunch was good and the walk very pleasant. We were keen to take in the Clyne Gardens where the rhododendrons are a mass of colour; really worth the visit.

Driving along the other day I suddenly wondered where does tarmac come from? I think you might have guessed by now that this is rhetorical, and I am going to inform you. Correct. Tarmac or asphalt was discovered by Edgar Purnell Hooley, born in Swansea in 1860. He noticed that tar, when accidentally spilt on crushed rock, made a remarkably dust-free pavement material. He named this material tarmacadam, by prefixing “tar” to the last name of John MacAdam, the Scotsman who developed the use of crushed stone for paths and roads. In 1904, Hooley patented a process of making tarmacadam, presumably refined in the patent from simply “take some tar and spill it on crushed rock”. The name tarmacadam soon became shortened to tarmac.

Tar was a by-product of coal gas production. Now we use natural gas, tar is no longer available and it has been completely replaced by bitumen. So what is bitumen?. Well, bitumen is an oil derived product; chemically it is a complex mix of high molecular weight hydrocarbons, and in that respect is quite similar to tar.   According to the Refined Bitumen Association, we use about 1.5 million tonnes of bitumen every year and 85-90% of this is used on roads.

I have had an ongoing interest in another construction material for over 15 years; sand and especially dredged sand. So I was interested to read of a recent two-volume book entitled “A Century of Sand Dredging in the Bristol Channel”. This book has apparently been nominated for the Diagram Award for “bizarre and sometimes intentionally strange book titles”. When I found out about this award, I could not help taking a peek at some previous winners:

1999: Weeds in a Changing World
2000: High Performance Stiffened Structures
2001: Butterworth’s Corporate Manslaughter Service
2002: Living With Crazy Buttocks (what!)
2003: The Big Book of Lesbian Horse Stories
2004: Bombproof Your Horse
2005: People Who Don’t Know They’re Dead: How They Attach Themselves to Unsuspecting Bystanders and What to Do About It
2006: The Stray Shopping Carts of Eastern North America: A Guide to Field Identification

I do not understand how Lightweight Sandwich Construction by J. M. Davies did not make the winning slot though.

My interest in dredging arose because I noticed a loss of sand on a beach I knew very well and, on further enquiry, discovered that sand dredging was taking place just down the coast from this beach. Cutting a long story short, dredging at that particular site has now stopped; principally due to economic rather than environmental reasons. Although it is difficult to tell conclusively, I think the beach is improving. However, as the two-volume books would tell you, dredging is still going on in the Bristol Channel, removing massive quantities of sand. Here is a picture, taken just a week ago, of a dredger off the Gower coast near Worms Head. The boat was static, probably waiting for the tide before it docked at Burry Port.

Indeed, there is a recent outline application for dredging of up to 1,800,000 tonnes of sand per year for a period of 15 years in a new area. This is a truly staggering amount of sand despite the fact that it represents, according to the dredging industry. less than 5% of the total sand apparently there.

There is plenty of very technical “scientific” judgement asserting that current and future dredging has negligible environmental impact. But the oceans and estuaries are exceedingly complex in terms of water, wind and sediment movements and I have no confidence that the mathematical and other models currently in use account for all of the complexity involved. I am very much aware that the Costa del Sol used to have many fine sandy beaches, according to locals that have not moved away. But the beaches have gone now and (or because) most of the sand used in the extensive building development was dredged from the sea. Almost all the building sand used in South Wales originates in the Bristol Channel and, of course, we cannot just stop dredging. But surely we should plan to be more sustainable in the future and not just exploit this resource to death.

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One Response to Swansea Bay, tarmac and sand dredging

  1. The First One says:

    You made me snort out loud with laughter x

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