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Letters: Tidal barrier solution better than dredging

Dredging

False economy: Dredging on the Levels will not solve historic flooding issueshe Levels will not solve historic flooding issues

I wish to comment on Murray Palmer’s letter relating to comments attributed to me advising that dredging of the Somerset Levels and Moors would have little or no effect, in the article “Tidal power barrage could protect Somerset Levels” (NCE 27 March).

My comments about dredging, although broadly correct, relate to only one of my points. To clarify, my main points are that: (i) the weather conditions last winter were extreme, both rainfall on land and high water levels in the Bristol Channel, with these unique conditions needing new and more comprehensive modelling studies, rather than simply making judgements based on past flood mitigation measures; and (ii) the hydraulic gradient in the region is very small, and dredging by itself is unlikely to have much effect, and we need more substantial flood mitigating measures, including improved catchment management.

Secondly, Murray Palmer also advises that “civil engineering students will know that the conveyance of an open channel is a function of hydraulic gradient, bed friction, channel slope and cross-sectional area” etcetera.

However, students will have also have been taught in the first year at my own university about non-uniform and unsteady flows, which occur in this region. Our students will appreciate that for the Somerset Levels the conveyance is far more complicated than just assuming steady uniform flow and that it would be more productive to focus on increasing the hydraulic gradient than the area of flow, where the velocity is small.

To convince any hydraulic engineer that dredging will be effective, we need a full dynamic model from the outer estuary right up to the catchments.

In my experience such a model is likely to show that a tidal exclusion barrier and including pumps - similar to Cardiff Bay Barrage, or a Bridgwater Bay lagoon - will be much more effective than dredging alone and a better long-term solution.

  • Roger Falconer (F) FalconerRA@cf.ac.uk

 

As a civil engineering ‘student’ now in his 80th year, I would courteously remind Murray Palmer that open channel hydraulics is a complex matter, and the parameter of sediment charge or load may be another matter to include in his definitive list for analysis of the sediment laden River Parrett.

How much simpler and economic it would have been to have adopted the recommendation of 30 years ago to construct a tidal barrier on the River Parrett to prevent the twice daily ingress of sediment from the River Severn that everyone is now so exercised about.

  • Patrick McMillan (M) patrick.mcmillan@icloud.com

 

Swallow

Capped: The ‘swallow’ as recorded by the Dorking & Leatherhead Advertiser

Geotechnical: Swallows pictured in the Mole Gap

Clive Edmonds in his interesting article refers to “sinkholes” (NCE 27 March) in the Mole Gap. Where the river Mole flows through the North Downs over fractured chalk, they are known as “swallows”.

The attached article from the Dorking and Leatherhead Advertiser of 1 January 1937 (courtesy of the Dorking Museum archive) describes a swallow 60 feet (20m) deep and how a dome was built over it when the A24 was being widened and realigned. The size of the dome can be judged from the men in the photograph.

  • Ben Tatham, St Anthony, Pilgrims Way, Westhumble, Dorking, Surrey RH5 6AW

 

Profession: A childish approach to sexism

In the sexism debate it’s vital to understand the difference between conscious discrimination and subconscious preference.

It is well established that about 70% of people carry a subconscious link between males and scientific careers - Google “gender/science IAT” and you’ll see what I mean.

Evidence suggests this association is set in our heads before we turn eight, so no wonder STEM (science, technology, engineering and mathematics) ambassadors like me struggle converting girls who are doing GCSEs.

Yes we need to remove prompts like “manpower” and the “men at work” sign that reinforce our preference, but we also need to look at what cues our kids are picking up.

Maybe the answer lies in children’s books…

  • Matt Humphrey (M), humpyjeff41@hotmail.com

 

Profession: Man, I feel like a human

The misuse of the word “man” is getting tiresome and it is time common sense was applied.

The Oxford English Dictionary primary definition of “man” is: “a human being.” Consequently there is no need to use “chair” or “chairperson” instead of chairman and certainly not “staffed” instead of “manned”.Enough is enough of this outdated feminist perversion of the English language. Let us be sensible.

  • Donald Wroe (F), Barnside, Bouth, Ulverston LA12 8JB

 

Profession: I can’t sustain these awful practices

I was pleased when Mark Hansford began editing NCE, as his pieces have always been well-written and thought-provoking and the change marked a noticeable reduction in management mumbo-jumbo in your pages.

But your 27 March editorial… what on earth are “sustainable business practises”?

Attempts to add a gloss of green credibility to articles by slipping the word “sustainable” into every other sentence should be banned by your style guide.

And while we are at it, please learn to spell the word “practices” (the noun)!

  • Peter Watts (F retd), peterwatts@fastmail.fm
  • Editor’s note: Apologies Peter, got swept up in a little awards fever there. Hopefully, normal service has now resumed.

 

Profession: When the client is not always right

The winner of the Young Consultant of the Year is quoted saying: “As engineers we need to be working on our client’s behalf and not pushing things just because we think it’s right” (NCE Consultants File 2014).

I agree with Gavin White’s wish for engineers to be involved early in the design process, but engineers should not withhold their views from the client on important design and construction matters if “we think it’s right”.

  • Peter Mason, peterfordmason@hotmail.co.uk

 

Health & safety: Time to review attitudes to insurance

John Carpenter’s article enquires why crucial data relating to the causes of serious incidents is not obtainable in the UK (NCE 20 March). Based on personal experience derived from many collapse investigations on behalf of insurers, engineering claims are invariably settled in confidence under terms dictated by the insurers and their lawyers - forensic evidence remaining sub judice.

Vested interests cannot be allowed to indefinitely withhold forensic evidence through which civil engineering understanding evolves. Accident investigation is transparent in other professions such as aerospace - so why not civil engineering?

Perhaps John Carpenter’s “better way” would be a Statute of Limitation on insurance confidentiality, maintaining claim settlement details sub judice for a given period (say 10 years).

Forensic evidence could be publicly available afterwards, on the understanding that previous insurance settlements are not revisited.

The ICE should contact the appropriate authority to initiate a long-overdue review of construction insurance attitudes.

  • Martin Rush, (M retd), rushmartin@yahoo.com

 

Energy: No more nuclear power stations

In his letter Jim McCluskey reminds us of the world’s four grave nuclear energy emergencies between 1957 and 2011, the last of which at Fukushima is reported to have economic consequences of £150bn to £300bn (NCE 13 March).

Do we not remember the uproar in America when BP was the cause of oil pollution in the Gulf of Mexico and livelihoods were affected? The clean-up cost there, although in the billions of pounds, is but a negligible fraction of that projected for Fukushima.

Scotland will not have new nuclear power stations, and following Japan’s disaster, nor will Germany; a blow for common sense.

If there is any doubt that the deaths, illnesses and human sufferings arising from the aforementioned radioactive accidents are not already too high a price to have paid for nuclear electricity, try adding up the taxpayer costs of decommissioning nuclear stations.

And if anyone is still unconvinced by the aforementioned and yet to be incurred costs, how palatable is it that the UK government is to pay guaranteed sums to the generator of the next nuclear power station?

Immediate cancellation of all such planned stations is a must, a “no-brainer” to use common parlance, with the budget provisions made in respect of these stations being re-allocated to research into the production of electricity by non-nuclear means.

  • Gordon Bathgate, gordon.bathgate@gbc51.com

 

Transport: Blackpool’s tramway copes with saltwater

Nigel Craddock raised questions about Great Western rail electrification (Letters last week). The restricted loading gauge of the Severn Tunnel is indeed a challenge.

A simple solution would be to re-track with the LR55 system that lowers the rail head by more than 300mm, without having to excavate the tunnel invert.

Meanwhile, the exposed track at Dawlish can be compared to the Blackpool promenade tramway, which has been exposed to salt water, wind and sand for well over 100 years without any serious problems to the wires or supply cables, even when the tracks are under water. Dawlish should be fine.

  • LJS Lesley, 30 Moss Lane, Liverpool L9 8AJ

 

Health & safety: Vietnam and Laos ditched road changes

I would agree with Michael Dunn’s comments in his letter “African lessons still need to be learned” (NCE 13 February).

Taking into account that in 2003 research body TRL, with Department for International Development (DfID) support, produced comprehensive guidelines, based on the Overseas Road Notes together with regional experience, for the construction, rehabilitation and maintenance of rural roads in Southern Africa (SADC Guidelines - Low Volume Sealed Roads) - it would indeed seem that “we are reinventing the wheel” in looking to pursue a programme, again with DfID support, on alternative surfaces.

The African trials are the third time to my knowledge that the multi-surface alternative programme, which caused Dunn’s ire, has been tried - the others being in Vietnam and Laos.


In the latter case, trial sections were built using bamboo reinforced concrete, concrete filled Geocells, hand packed stone, mortared stone, concrete paving blocks, sand seal, Otta seal and engineering natural surface.

However, the cost per kilometre of the trials was found to be greater than the cost of that country’s well tested standard double bituminous surface treatment, and were therefore not taken forward to full scale works.

  • Richard Tomkins, 27 Denmark Road, London SW19 4PG

 

Health & safety: Putting a price on machine safety

I refer to the Opinion piece by Malcolm Kent “Questioning machinery safety standards” (NCE 13 March). As chairman of the BSI mirror committee for CEN machinery safety standards I support much of what he says.

I agree that the ideal CEN committee consists of regulators, users and manufacturers. It is a great regret that recent financial cuts have drastically reduced participation in standards making by Health & Safety Executive specialists.

Regulators and users are needed to balance the manufacturers, who I have found are not always keen on embracing “state of the art” when the status quo has commercial attractions.

I would certainly encourage user participation. “If you are not in it you cannot win it” is the expression often used by standards makers. However, in that respect I think the UK has a good record, and by way of example would highlight machine categories such as drilling and foundation equipment as well as tunnelling machinery, where in my personal experience there has been extensive and successful participation by UK user organisations.

  • Donald Lamont, chairman BSI committee B/513, donald@hyperbaricandtunnelsafety.co.uk

 

Flooding: Baveystock right to call for UK flooding plan

I strongly support ICE director general Nick Baveystock’s call for swift action to develop a long-term flood protection plan (NCE 27 March).

The UK engineering profession is currently able to confidently solve the recent and growing number of major flooding problems, like those on the Somerset Levels.

The biggest and most significant challenges to achieving this are for society and its political representatives to decide what standard of service is appropriate, what is an acceptable price tag to provide this and how this should be funded.

Having decided on that, it is essential that cost effectiveness and sustainability are maximised regarding flooding solutions, and to achieve this we should adopt an integrated, risk based, river basin management approach. The tools to do this already exist, including verified simulation models and time series rainfall.

Major capital intensive solutions at the outlet end of river basins (for example a tidal barrage excluding turbines at mouth of estuary) should only be considered after upstream options (for example flow attenuation) have been exhausted and are not sufficient to achieve the required standard of service.

  • Gerry Moss (F retd), a-g@gandamoss.plus.com

 

  • NCE welcomes letters from readers. We attempt to print as many as possible, which means letters longer than 200 words are likely to be condensed. Send your views and opinions to: The Editor, NCE, Telephone House, 69-77 Paul Street, London, EC2A 4NQ; email: nceedit@emap.com

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