SMB sand conveyor drain

| 15/10/2019 | 53 Comments

Courtney Platt writes: While studying marine biology in college, the main point I learned about marine sediment transport is its fluidity. When I was piloting Cayman’s deep subs in George Town Harbour, the scariest moments were the occasional, massive silt clouds that would spill over the wall. They descended upon the sub, suddenly carrying us downward in zero visibility under a hundred yards of falling sand. Tremendous volumes of sand regularly slip off the reef shelf, never to return.

According to two respected old salts, Bob Soto and Kem Jackson, we will theoretically lose sand faster from Seven Mile Beach by deepening the spill-way, which I also believe plausible and which is consistent with Seymour’s report quoted in government’s rebuttal to CCMI.  

Seymour concludes: “At the south end, there is no transport into the system because it is the end of the line. As a result, the beach begins to disappear, beginning from the south and working northward.” Seymour assumes that because the harbour is at the end of the line for sand transport and not the origin, that what happens there is of no consequence to SMB. And yet, he points out that the sand begins to disappear from south to north! This makes the harbour the main exit point over the wall for sand moving south from SMB. It’s the drain!

Severely depleted from extremely common to very rare, two of our largest squab (Rainbow Parrotfish and Midnight Parrotfish) thrill visitor Stacy Frank on the stern of the Kittiwake (Photo by Courtney Platt, click to enlarge)

Physics suggests that creating a pit on the edge of the spill-way and then stirring the sand in that newly enhanced drain basin with ships’ thrusters could only accelerate the sand loss there.  The resulting cascade effect could reach all the way back to the beaches from whence it came. It would certainly affect the volume of sand returning north from the harbour in the summer.

Sand acts like a liquid, always seeking the lowest point. It will inexorably flow into and toward the pit if we dredge the harbour from its current 20-40′ sloping depth down to the desired working depth. It would certainly affect the volume of sand returning north from the harbour in the summer.

Though the annual net shift is to the south, we have long known that the sand moves south in the winter and back north to a lesser degree in the summer. Any sand that might normally shift back north past the pit will be effectively cut off right there, ending the seasonal resupply from Jackson Point. This doesn’t look good, especially for the southern end of SMB, where it would be felt first. It’s a very reasonable theory worth serious consideration before dredging the harbor. 

We have already done great harm to SMB by building too close to the sea and not on stilts, creating energy reflectors that back-wash sand off the beach and according to Seymour, eventually down to the harbor and over the drop-off. Numerous sand chutes also spill off the wall all along the way. 

At the same time that we constantly lose uncounted tons of sand we have also alarmingly reduced, and continue to reduce, the major producers of sand… our big parrotfish (squab). A recent study by the University of Exeter in the Maldives found that over 80% of all new sand there actually is parrotfish poop.  

We know we already have a problem. SMB is visibly shrinking. I believe we need more stilts and/or greater set-backs in shoreline planning and we need to let the parrotfish recover through regulation and public education. Add the fact that live hard coral coverage has dropped from 80% to 20% and SMB looks to be in serious trouble. 

There is hope if we care enough. Given enough political will, we can change our destructive behaviour. Are we willing to learn and change? Build smarter? Protect our parrotfish? Ready to support and listen to marine biologists? Having said this, is it wise to risk adding yet another detriment to SMB’s precious gift by enlarging the drain at the south end of the sand conveyor?

Good stewards do not wantonly destroy God’s gifts of renewable natural resources in exchange for concrete. Want a murky parking lot instead of coral reefs in clear water? Those of us who have spent a lot of time looking at this have many legitimate, serious concerns and not just for the harbour itself or the sand on SMB. 

This plan seems to be heavily weighted in red ink. If you are a registered voter, you owe it to yourself and to Cayman to learn about that ink and then get out and vote your conscience for Cayman’s future. Be sure to secure and deliver an absentee ballot if you will be away on vacation or are living off-island.

The referendum vote has been set for 19th December, 2019.  Because the bar is 50% of all registered voters, every failure to vote is by default a yes vote for the port.


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Category: development, Local News, Viewpoint

Comments (53)

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  1. Courtney Platt says:

    All experienced Caymanian seamen know that throughout the winter NE winds are wrapping waves around NW Point, carrying sand around that point. Periodic norwesters then pump the sand south along SMB to a greater extent. Likewise, throughout the summer SE winds wrap waves around Pull or be Damned and Jackson Point. Periodic southwesters pump the sand back into the harbor and up SMB to a lesser extent. There is no visible physical interruption in the sand conveyor belt in aerial photos anywhere along the route between the harbor and SMB. It appears to be contiguous and there is no reason to assume there is a disconnect between the harbor and SMB. Less movement from south to north than vice versa, but not no movement, which is the concern.

  2. Rick says:

    Courtney, I have concerns over the way this port is being built and the ancillary issues surrounding it. However, your arguments lack merit and some are downright disingenuous. You are making a deliberate attempt to mislead viewers. As a person who is not sure whether or not I should vote for or against this port project, you simply push me away from voting against the port. If you want to increase support for the cause of not building a port, do not be so lazy; do proper research and deliver the arguments for and against. Your reasoning on the movement of sand is a joke, which makes me disbelieve most of what you claim to experience. BTW, did you take a photograph of all that sand you saw pouring over the drop-off? Publish the evidence. I simply do not believe you.

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  3. Anonymous says:

    Are the Baird people smart fish?

    • Anonymous says:

      Don’t know if they are smart fish, but looking at their website they sure have done a lot of impressive projects related to ports and the marine environment around the world. Wayne Panton made the right decision to bring them in to do the environmental assessment.

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  4. To says:

    Exactly! Thank you for joining me. I keep bringing it up again and again, but everyone seems to prefer being 🙈🙉🙊.
    Your comment must be repeated in capital letters until even the dumbest individual gets it!

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  5. Anonymous says:

    I am no rocket scientist or even a coastal one, but I will bet everything I have in this world on the surety that dredging the Harbour will not have a positive impact on Our greatest physical asset which is Seven Mike Beach.

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  6. Anonymous says:

    Where is all the environmental passion and interest in resolving and preventing the environmental disaster of the existing dump Mt. Trashmore. This single issue is far more important than all others for this country because toxic leachate seeps through the porosity of our under lying limestone geological sub-straits over to SMB and into north sound constantly for many many decades. This has already caused deterioration and damage to our corals and the marine environment yet you and all your followers have done nothing or said anything about the greatest environmental disaster in this country’s history.

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    • Anonymous says:

      Exactly! Thank you for joining me. I keep bringing it up again and again, but everyone seems to prefer being 🙈🙉🙊.
      Your comment must be repeated in capital letters until even the dumbest individual gets it!
      Not just coral, but every single living thing on this rock is deteriorating, gets damaged, ill, dies because of the Dump. On the land and in the surrounding sea.
      Meantime they spend money on all kind of crap, lavish entertainment and travel when every single dollar must be mobilized to resolve waste management crisis.
      National emergency must be declared and the brightest minds in the world recruited to address the crisis. Only Japanese can do it fast, efficient and in compliance with 21st century requirements. Japan is the country of islands. They know how.
      The cost would be astronomical, but the longer you wait the sooner Grand Cayman will become uninhabitable.

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    • Anonymous says:

      Bermuda used to dispose of its bulk waste such as scrap metal, cars, etc., and blocks of cement-stabilized incinerator ash (produced from burning garbage) in a foreshore reclamation site, i.e., a seafill.
      Chemical analyses showed [2010] that seawater leaching out of the dump [seafill] regularly exceeded water quality guidelines for Zn and Cu, and that the surrounding sediments were enriched in multiple contaminant classes (metals, polycyclic aromatic hydrocarbons, petroleum hydrocarbons, dioxins and furans, polychlorinated biphenyls and an organochlorine pesticide), i.e., there was a halo of contamination. When compared against biological effects-based sediment quality guidelines (SQGs), numerous sediment samples exceeded the low-range values (where biological effects become possible), and for Hg and Zn exceeded the mid-range value (where they become probable). A few meters away from the edge of the 25 acre seadump lies a small coral patch reef, proposed as most contaminated coral reef in the world. (paraphrased from Marine Pollution Bulletin
      Volume 60, Issue 11, November 2010, Pages 1993-2006)

      I don’t know what is happening in Bermuda right now. I used the above information for analogy to what is happening in Grand Cayman today.

      As 10:51 rightfully noted,
      ”…toxic leachate seeps through the porosity of our under lying limestone geological sub-straits over to SMB and into north sound constantly for many many decades…This has already caused deterioration and damage to our corals and the marine environment “. So the mechanism is no different than that of Bermuda.

    • Anonymous says:

      10:51am – That’s a different article. You are commenting on the wrong link.
      The dump is another big issue but this article is about sand.

      Why don’t you write a Viewpoint about that yourself?

  7. Anonymous says:

    Mr. Platt, like all the other alarmist you think and have determined that the dredging in GT harbour for the cruise berthing facility will produce and result in a huge deep hole and disrupt the flow of sand solids in suspension. Nothing could be further from the truth for there is no hole at all and the small thin wedge of seabed dredging in the harbour only extends out to the 35 to 36ft depth bathymetric and not out to the drop off as you infer. GT harbour sand does not move north into the SMB system and cruise berthing will eliminate the all day thrusting by cruise ships in GT Harbour to maintain their DP positioning in the harbour.

    The movement of sand in the sand conveyor along the south coast does not enter into the movement of sand on the west coast for the sand produced along the south coast by marine life, erosion and algae reaches southwest point at Sand Cay and is lost over the drop off wall as determined by the DOE consultant expert on the study of sand movements around the island, namely Dr. Richard Seymour. It does not do a hard right turn and flow north into GT harbour and enter the SMB system. The north coast sand conveyor transports sand along the north coast with some of that sand spilling into North Sound and the remainder flowing to North West Point where season weather and nature pushes it into SMB. SMB was once a mangrove strip and in Dr. Seymour’s own words, the only reason we have SMB on the lee side of our island is the occurrence of North Wester weather fronts passing through the region each winter transporting the north coast sand into SMB system. In Dr Seymour’s words the SMB system ends at the south end of SMB and there is no interaction between GT harbour or between south coast and north coast sand conveyors. For the general publics knowledge, there is not one single current flowing along our west coast, there are multiple currents both inshore and offshore which oscillate in opposing directions north and south each day. This has all been monitored, recorded and studied from data collected from multiple instruments deployed over recent years.

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    • Anonymous says:

      Who is Dr. Richard Seymour and what are his qualifications?

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      • Anonymous says:

        He is the DOE chosen consultant scientist from the Scripps Institute, Google his name he is a well known expert in his field.

    • Anonymous says:

      Don’t you think this is too much to risk for the greed of a few?

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    • lightbulb says:

      8:21am
      please share with us, where is the GT harbor you are referencing?
      For all the knowledge you think you posses, I am amazed you seem to not know what a harbor is.

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    • Chris Johnson says:

      What Northwester weather. That was years ago! Dr Seymour please get up to date by visiting Cayman again.

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  8. Anonymous says:

    Truly I admire Courtney’s passion, we all need some of that in our lives.
    But, studying some marine biology is a far cry from being a coastal process engineer or scientist which he is definitely not. He takes great pictures and spends a lot of time in the ocean but he is not qualified in any fields that are relevant to this project other than taking pictures for the new brochure.

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    • Anonymous says:

      Yes 8:06, but the Baird Report from 2015 written by engineers and scientists says basically the same thing as Pratt.

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  9. Anonymous says:

    Can someone explain why the cruise ships would build a dock which will destroy 7 mile beach which will in turn reduce cruise passengers wanting to come to Cayman. Cruise ships make money and 7 mile beach is their treasure.

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  10. Anonymous says:

    You lost your scientific argument when you brought God in to it. Other than that, valid concerns.

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    • Anonymous says:

      Ask a Scientist or google what the “God” particle is

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    • Anonymous says:

      I don’t take advice from Old Salts.

      I respect both of these men but they have no credibility with me about this topic.

      Come on folks would you take advice from Old Salts about raising your children, buying a car or building a home in this era. Nooooooo

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    • An atheist says:

      It is a figure of speech. Has nothing to do with religion. I didn’t even notice that. God’s gifts, nature’ gifts, creator’ gifts, whatever. Life on earth is a miracle. Who created it is the question that won’t be answered.

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      • Anonymous says:

        At times. In this instance however it was deliberately used in an attempt to invoke the emotions of those who believe that crap.

    • Anonymous says:

      If you re-read this excellent article I do not think that you will find that God is part of the argument at all

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  11. BeaumontZodecloun says:

    Thank you for your thoughtful and thought-provoking viewpoint. Conservation should be one of our prominent endeavors in these difficult times. Without our natural resources, our tourism model, as well as our children’s future is very dismal.

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  12. Anonymous says:

    Wow

    Good bye seven mile !!!

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  13. Anonymous says:

    If you want to see the impact of sand movement on coral try diving the area off Dixie Cemetery.

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  14. Anonymous says:

    Why can’t people just accept progress for what it is?

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    • Anonymous says:

      Do you mean self destruction?

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    • Anonymous says:

      So doing a project that would effectively destroy Seven Mile Beach is progress?

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    • Anonymous says:

      If this progress you are referring to destroys and make the area worse off than it is presently then it is not progress-.more like wanton destruction. We might have to put up with it if the knucklehead Premier and deputy goes ahead with this disaster but we will never accept it. You can go and tell them that for those of us who are against it!

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  15. Anonymous says:

    I would be very interested to know if the Baird Consultants who are experts in this area, share the Courtney Platt view? Does anyone know?

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    • Anonymous says:

      Baird are now part of the verdant isle consortium – any assessment needs to be independent. I would no longer trust them than I do this Government sadly. Misinformation, spin, a complete lack of information provided to voters. Why is that?

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      • Anonymous says:

        Baird are professional and they are not going to suit their results to accommodate Verdant. That is not how it works in the environment assessment game.

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        • Anonymous says:

          That is how it should work. Professionals must be independent from parties that have an interest in the results.

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        • Anonymous says:

          LOL

        • Anonymous says:

          Hahahahahahaha! Good one 10:27p Put the rum down. It’s bed time.

          • Anonymous says:

            No 9:50 it’s time for you to read the Baird report from a few years ago on the proposed port and Seven Mile Beach. Don’t tell me they are now going to completely contradict what they wrote before. Baird are professional and have no political skin in this stupid Cayman game. Simply look at the studies they have done around the world.

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        • Anonymous says:

          Baird are deeply conflicted. After their 2015 PEIA, they were separately commissioned to produce a Port Authority report on the remediation of the cargo area. You can google it from Baird, or find on GIS.

    • Anonymous says:

      Baird Consultants are experts on Cayman??????

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      • Anonymous says:

        Baird are one of the top expert groups in the world. Just Google and see what they have done around the world. They are not going to sell out their professional reputations as scientists just because Verdant has hired them.

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      • Anonymous says:

        Yes they are experts on the port and Seven Mile Beach. Just read their report from a couple of years ago. Does not get more thorough than that.

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      • Anonymous says:

        Yes they are experts and being outsiders they can give an honest professional assessment. A Canadian company is not going to come to Cayman to trash their international reputation.

  16. Anonymous says:

    Courtney is an animal. I went down to 850ft years ago in a submersible that he piloted back in the 80s.
    He has always been a hero of mine.
    He is a genuine campaigner for the planet.
    God bless you, Courtney.

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    • Anonymous says:

      Courtney may be an animal but I want to know if he is a fish with the expertise to articulate effectively what is really happening to the sand, coral and fish on Seven Mile Beach.

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      • Anonymous says:

        Courtney is a smart animal and you are not!

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      • Chris Johnson says:

        May I suggest he knows more about the subject than you. Unless you can advise us of your own credentials may I recommend you keep your thoughts to yourself.

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        • Anonymous says:

          Chris, Suggest you read the Baird report from 2015. There are some/some differences between what Courtney is saying and what Baird is saying. Of course, if you think Courtney is more of an expert than Baird’s people then it will not make much difference to you.

    • Rick says:

      I think you just identified his motivations for lack of objectivity.

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