Why Antrim road is slipping (Part 1)

Dr. Lennox Honychurch/photo taken from: www.facebook.com

The ongoing slippage of the Imperial Road at Antrim Valley is a serious challenge to communications across the island. This road is the main link between the capital and Douglas-Charles Airport as well as communities along the north and east coasts. With the alternative Layou Valley road under repair and the Warner-Soltoun road seriously compromised, the situation at Antrim is even more crucial. A side road from Canefield through Cochrane village to Springfield provides an emergency by-pass but it is too narrow for regular use.

Long before Tropical Storm Erika in 2015 and Hurricane Maria last year, engineers, both local and foreign, have been debating the cause and possible solutions. The reason they do not appear to be finding the answers may be that they are not fully aware of the history of this section of the road. They may not have grasped the geology of this valley’s formation which is causing the constant slippage. It is important that all civil engineers working on our roads know the background to their construction. This includes former routes and building methods and even the administrative politics at the time.

First, the geology: The surrounding mountains are part of the rim of a huge ancient crater forming a semi-circle around Morne Trois Pitons. If you stand at a viewpoint just past Sylvania you will see this rim forming an arc of peaks to the northwest all the way around to Morne Neg Mawon. The Antrim peak itself is called Morne Cabwit Mawon and the other peaks and ridges in the line have names such as Bona Vista, Morne Cola Anglais, Morne Boyer, Despor, Deux Saisons and Morne Couronne.

This rim of mountains was formed thousands of years before Morne Trois Pitons emerged. The rim is composed of hard igneous rock that turned solid as lava came out of the volcano. The later, Trois Pitons eruption, covered these earlier igneous rock mountains with volcanic debris. This includes ignimbrite, ash, and red ferrous clays. These clays can be seen at Red Gully and all along the sides of the valley. They are constantly slipping over the smooth, older rock layers beneath. But Antrim is a special case.

What is happening at Antrim is that volcanic material from these two seperate geological periods are converging on one critical spot. A large lake once existed in this part of the valley. Eventually, its western wall collapsed and burst down the gorge to Check Hall. The old lake bed is still there, covered with thick grey silt clay that holds water and is sliding into the river.

If you cross the Antrim River to the other side of the valley, the lake bed continues. Pools of swampy water dot the landscape between huge boulders. The villagers of Massacre used to grow dasheen here and interestingly their name for the area was ‘L’etang’, Kweole for ‘lake’. The former borders of the lake can be clearly seen as a bowl spanning the entire valley.

If you go into the bush opposite where DOWASCO is now building a new tank you will see huge smooth boulders the size of small houses that once formed the sides of the old lake. Go further and you will see the cracked concrete floor of the Bunting’s house abandoned because it was splitting in half as the earth moved.

The hillside along the road is made up of earth and fallen rocks. This debris is from the top of the plateau of Morne Cabwit Mawon and it is resting against the solid mountain. Water from a ravine on the mountaintop is seeping between the hard rock and the loose debris causing it to slide into the old lake bed. The main road lies along this zone of seepage and therefore the road slides also. A bad engineering decision a few years ago to dump thousands of tons of excavated Red Gully clay on this delicate site has made it even more volatile. The more ‘tarrish’ that is dumped to shore up the road, the more the added weight causes it to slide. It is a vicious circle.

In 1900, British Administrator, Hesketh Bell, directed the construction of his ill-fated ‘Imperial Road’ through this area. Road workers were killed by a slide here. Again, in the 1916 hurricane the whole hillside collapsed. Although appearing safe for some years it has never been entirely stable. Now it has reached crisis point. Next week we look at the early engineering politics of the road and possible solutions, including the construction of a completely new highway elsewhere.

 

A diagram of the situation at Antrim Valley causing the slippage of the main road.

Article Link: Why Antrim road is slipping part 2

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58 Comments

  1. Rassheed
    May 17, 2018

    According to the sketch the road is build/constructed on water. Therefore, the only solution to this never ending problem would be to build a tunnel under the Antrim Valley. But isn’t it where Lennox Honeychurch has his property? Just asking.

  2. Nan
    May 17, 2018

    Dr Honychurch has a wealth of knowledge regarding Dominica and its structure. The Government should utilise that knowledge and include him, or seek his advice, in decisions such as this.

    • Rassheed
      May 21, 2018

      The government has been “utilising” him already.

  3. Wil
    May 16, 2018

    Very interesting. As someone with geotechnical engineering experience, this makes perfect sense. Now is that sleeping water can be diverted away from that area, and lightweight backfill use replace some of the existing soil, that might help. Still needs some extensive studies to verify the slip surface to come up with a possible cost-effective solution. The heavy rainfall in Dominica would require massive diversion drains. This is no easy or cheap fix.

  4. Me
    May 16, 2018

    My grandpa worked on this road. I recall he saying that this area was always waterlogged and many landslides happened. He said they once had to get big trees from norway to put below to stabilize the ground and then used soil to cover it up. That is why I am always fearful in using that road

  5. Lennox Honychurch
    May 16, 2018

    Just trying to provide some information and as usual get it in the guts from some. So it is. We persevere regardless. And here is some background:

    1. Although I may not be an engineer I have researched over 150 years of engineering reports on Dominica since the first department of Public Works was established in the 19th century. If this was an academic paper you would get the references but these articles are restricted to 750 words.

    2. As to geology, papers produced by the Seismic Research Unit of UWI at St. Augustine, Trinidad, cover much of this ground. Their publication: Volcanic Hazard Atlas of the Lesser Antilles, has geological maps and diagrams of Dominica which explain the whole Trois Pitons complex.

    3. My family used to own Antrim Valley estate and over the two decades that I lived there I have explored every corner of these ridges and valleys. I know the place by heart and I have explored it with geographers and geologists.
    So sorry that I upset some people so much.

    • Shaka Zulu
      May 17, 2018

      No need to apologize. “Long before Tropical Storm Erika in 2015 and Hurricane Maria last year, engineers, both local and foreign, have been debating the cause and possible solutions. The reason they do not appear to be finding the answers may be that they are not fully aware of the history of this section of the road. They may not have grasped the geology of this valley’s formation which is causing the constant slippage”. After 150 years we are still trying to figure out what you explained then we have a learning problem. I honestly think your atempt to put historical perspective is noble and i think some of what you explained may be occuring. However assumption of subsurface activities based on what you see at the top will lead to inaccuracies without the availability of subsurface investigations. I also said if that wasvyour opinion you expose yourself to questions and nothing wrong with that. The only way to find solutions is by asking critical questions and analysing every

      • Shaka Zulu
        May 17, 2018

        Aspect. Some of your readers may be versed in other things. If the engineers geographers and geologist were not made aware of all the historical info you knew nor did they research prior to making recommendations then thats bad. Even if it is not an academic paper if you got info from UWI seismic research center cite it. Whether you like it or not your are Dr. Hunychurch so every document you post write in the public domain is an academic paper.
        The problem with US Dominicans we afraid to question things when we know better. I hold you to a higher standard because of who you are so your problem if you want to take it personal. Through questions we find answers and my response was not meant to be critical but to stimulate discussion and thinking which we dont seem ro be able ro do these days. I can also tell you the in and out of all ridge and valley where i grew up in Dominica but can only speculate on subsurface without geotechnical work and boring logs.

    • we are watching you
      May 17, 2018

      This road has been dangerous from day one and when it was initially constructed it was the only way of getting from the east to west of the island unless you went by boat. It used to be that one way to get to Portsmouth and Scotts head was by fishing boat before a road was built. When Antrim Valley road was constructed it was done with pick and shovel and had to be a very dangerous operation.

  6. My name
    May 16, 2018

    This Government will not listen, they simply cannot do the work, they failed Public Works, all they studying is Elections and money. Time for them to go! Thanks Mr. Honeychurch for this information hope all Engineers start studying this.

  7. PayAttentionMyPeople.
    May 16, 2018

    Thanks Dr. Most informative indeed .Google earth recently poblished new images of the planet , a very close study of the topograpy of the island would revele shocking truths about out island , and even provide us with a greater understanding of why nature seems to be on a rampage on our island these days . Starting from the south a close examination would indicate that new landslides in the interior of the island have cut new pathways forming new gullys and creating new water catchment zones where there were none. A serious drone study of island is needed so we could really determine what is really going on .
    THE HISTORY OF THE ISLAND IN THAT REGARD IS PRICELESS.

    IS IT POSSIBLE THAT THE AREA IN QUESTION MAY ACTUALLY BE SEATING ON AN ANCIENT VOLCANO……?

  8. Francis O. Severin
    May 16, 2018

    This is a very informative article, written in Dr. Honychrurch’s characteristic and signature accessible and interesting style. It is edifying to know what is happening beneath and around us as we traverse this evidently treacherous path. The article also confirms that indeed we must not exclude the historians as well as the social scientists from what, at first blush, appears to be solely engineering/scientific decisions. Indeed it is a truism to say that “all societies have been shaped by geography and history” (Gordon K. Lewis in Mintz & Price, 1985, p. 219). I look forward to Part II next week. Well done!

  9. Peace
    May 16, 2018

    Then why don’t you do some research and come back with your view on the matter? Unless you do that, you will continue to come across as angry and ill-informed.

    • Peace
      May 16, 2018

      Sorry … that was meant to be a response to notinterestedintheleast soft drink’s rant below.

  10. i will speak
    May 16, 2018

    i thought he was historian not a geologist? thats just my 2 cents

  11. gramaxone
    May 16, 2018

    :mrgreen: :mrgreen: ….most of allyou that saying good job dr. honeychurch never been to the places he is talking about… I am not saying that what he wrote is wrong, but it looks like it was just lapped up (except SZ) although no sources were quoted…last time I checked, history and geology were two separate things….although intertwined.. :lol:
    ….waiting to see when “climate resilient infrastructure” will be built, and not just “reasons” why antrim is “flocked”….it looks like he is trying to make excuses for the government…..see?…is god’s fault… :mrgreen: :mrgreen: :mrgreen:

    • langlou
      May 16, 2018

      poison. what u dontbrealise is that most of these information about Dominica can.be found in the archives in england….these people documented everything.. so take yoir head from your @$$ and educate yourself.

  12. jungle
    May 16, 2018

    As Dr. Honychurch clearly points out, road construction (with bridge construction, building construction) must start with geological or bedrock analysis. It must include analysis of water catchment areas and drainage pathways, climatic analysis etc. – an integrated approach. In addition, as he has emphasized in the Antrim case, local historical knowledge may be of key importance. Listen to the people and pay close attention to the past.

  13. jihan
    May 16, 2018

    Always a pleasure sir,well informed and makes sense,only if the fools in charge would take note.

  14. CONSCIOUS
    May 16, 2018

    This is why i have said bringing outsiders to work in Dominica cannot always be a good thing when this people do not know the history of the terrain. In the older days every corner in Dominica road had culvert. technology is always but to keep public works out of the country roads business is like removing the base of the country road network. We need new roads for sure to accommodate the increase in vehicles on the island. We are in need of safer roads as well. I realized after the Chinese resurfaced the road the was the first time we had so much water problem from Roseau.
    I guess we do not want to use the information of those who came before us.

  15. Eddie
    May 16, 2018

    Good work Dr. Honychurch. I home this historical and geological aspects will be considered in the future plans for the area

  16. Roger Burnett
    May 16, 2018

    Now that the Technical Officers in the Ministry of Public Works have this information at hand, I hope they will reconsider their present plan of cutting into the hillside and placing the road at a higher level. In doing so they would not lose face, but gain credit.

    Eight years ago, they were advised against placing the spoil from Red Gully at Antrim. Regrettably the advice went unheeded.

    The Ministry has on file details of a cost effective alternative solution, the essence of which is to take weight off the road rather than putting weight on. You don’t add more ballast to a sinking ship! The alternative solution offers recommendations for easing the steep gradient where the road passes over the eastern fault line, improving drainage and cushioning the effect of instability.

  17. UDOHREADYET
    May 15, 2018

    Dominicans haven’t yet realized that in certain places, instead of building a road you must build an overpass, elevated road, tunnel or bridge… even when there’s no obvious signs of water the majority of the time. While in Dominica on multiple occasions I saw engineers repeatedly try to build a road that was constantly washed away and all they kept doing was clearing debris and repaving, repaving repaving, its as if they kept making the same mistake but expected a different result. Challenge yourself to build something that hasn’t been done on the Island, try something new, it might be less expensive and more resilient in the long run.

  18. May 15, 2018

    When it is all said and done we are all to do for ourselves the good of living. Tell you the truth you see it as lies . Tell you the lies and from it comes the truth. I truly believe this article and its explanation of whats happening . With disbelief we can only seek further explanation our different source of info. Do this your self anyone mr.lennox said enough when no other came close. I believe and thank you again for a clear picture as a novis i think its stil clear.

  19. Zead Lloyd
    May 15, 2018

    Thanks Doc. A perfect example of why an integrative process is always necessary for proper solutions to be arrived at. Thank you.

  20. dasheen
    May 15, 2018

    This is the type of new I like. Please keep on producing topics like these. Very informative

    • Pas toutes D'cen aveg- plessieur ka garde'
      May 16, 2018

      Lol what are you thinking? BC your name is dasheen you think ideas are plants ?lol

  21. skepticalone
    May 15, 2018

    Excellent and useful information that anyone can see makes sense and explains why the road just keeps sliding no matter how much they “fix” it. Well maybe not anyone, there are still plenty of idiots who just want to get personal but they are not relevant to informed conversation anyway.

  22. Concerned Water Advocate
    May 15, 2018

    Thank you Dr. Lennox Honeychurch. This is very informative article, a reminder that as we talk “Resilient” and building better. There is indeed an urgent need to focus on the proper management of our Rivers and Watersheds.

  23. Fran
    May 15, 2018

    Not sure why they won’t consult you Dr. Honeychurch

    • Jheri
      May 16, 2018

      maybe because he isn’t a Civil Engineer

  24. Pedro
    May 15, 2018

    Great article Lenox! Clearly there is the need for a lot more technical geological analysis but also listening to stakeholders and others like yourself would be helpful. The gut reactions is always to clear and overlay again with tarish. But this begs the question of what next for the water system as well? I hope the government speeds up its risk assessment of the island as the past hurricane experiences might be only a small indication of what it is to come. Overlay on this the likelihood of a volcanic eruption and/or major earthquakes. Indeed looks ominous! Let’s hope it does not happen but start think of this risks. In addition the island needs to b ringed with alternate and safe road connections. Indeed the threat from threat from rainfall and runoff is very real and more immediate than a potential hurricane. Let us remember too that the number one priority of government is protecting its citizens. Gov’t can and should do more, if its only to raise the alarm on these things!

  25. Roger Burnett
    May 15, 2018

    I am very pleased that DNO is carrying these essential articles.

    ADMIN: Thank you for being one of the people who suggested it to us.

    • Jheri
      May 16, 2018

      good work Roger!

    • google
      May 16, 2018

      This article was in the New Chronicle and now its published by DNO.
      I guess with the approval Dr. Honeychruch.

  26. Sammy Ettiene
    May 15, 2018

    Wow, good information. Thanks Dr. Honychurch. I always loved history and believe we can learn from it. I hope the powers that be take heed to the information you are giving.

    Keep up the good work

  27. CIA Agent
    May 15, 2018

    Thanks for the explanation Dr. Honychurch.
    Looking forward to the next part.

  28. Real truth
    May 15, 2018

    The only solution is a man made tunnel…….

  29. Breathe
    May 15, 2018

    Wow! This is great info and an eye-opener. Thanks Dr. Honeychurch.

  30. PFPM
    May 15, 2018

    Lennox . Thanks for this. Excellent stuff!!

  31. LifeandDeath
    May 15, 2018

    Thanks for this edifying piece Dr. Honychurch. If you will please integrate the option of road from Mahaut up through Despor and out to Sylvannia..

  32. notinterestedintheleast soft drink
    May 15, 2018

    Once i see is lennox that write that i start to stupse already. Lennox is the man that had the whole Caribbean calling Kalinagos Caribs. I swear he does make up half his history as he goes along, until proven otherwise. Keep in mind that he is our most honored historian, even wrote the history of Dominica “According to him”. I think maybe our history needs to be cross checked, especially when concerning information around dominica’s independence. Maybe what is resorted to have happened, did not, or did not as he said it did.

    • Facts are Facts
      May 15, 2018

      Here’s an idea. Why don’t you go and research the facts yourself! Then you can come back and make factual pointers instead of spouting nonsense.

      Thank you Dr. Honychurch for that insightful article. Looking forward to more!

      • notinterestedintheleast soft drink
        May 16, 2018

        Here’s a better idea, while i research my own facts, why dont you double check what you think is facts as well and stop eating everything people put in your mouth. Clearly you are one of those who need to. not saying honeychurch is wrong about this one, but that we must stop accepting everything this man says as that. good advice thank you, but i hope you follow it as well

    • Sam Sara
      May 15, 2018

      I think you probably need to be cross-checked. Have you had your head up your ****** for long or is it a recent thing?

    • Dominica
      May 16, 2018

      The Kalinagos were called Caribs long before Lennox was even born, so what are you talking about. People do show their ignorance as a base of honour in Dominica, shame!

  33. BG
    May 15, 2018

    Thanks Mr Honychurch for providing knowledge outside of the “noise”.

  34. BG
    May 15, 2018

    Thanks for providing knowledge outside of the “noise”.

  35. Shaka Zulu
    May 15, 2018

    Mr. Honeychurch please put references for your geology information so the curious among us can check. It is strange that engineering fix was applied without proper geological reference and geotechnical assessment at the site. I would like to see the boring logs and the lithologic description of formations at the site and the scientific methods used to collect that data. Also what techniques were used to date the different strata or nonconformity.

    • Shaka Zulu
      May 15, 2018

      I kindly request Mr. Honeychurch provide reference for this reason. With his stature and name what he has presented above may seem factual to many readers. I am a Geologist by education who have done some field work mapping formations in Colorado. I have also taught Caribbean Geography for a couple years in Dominica prior to going to study. I am by no means an expert on Dominica geology but i have some knowledge and understanding to point out a few things. If Mr. Honeychurch is pointing out this scientific info as facts he has to reference documents and geologic research done because the last i checked he is not a PhD in geology. If the information above is his opinion or conlusion based on his observations he should state that and it is ok. However, when he does there are people like me who are going to have questions.
      Mr. Honeychurch included red clays as volcanic debris that seems to indicated clays came directly from volcanoes when infact clays are weathered material.

      • Shaka Zulu
        May 15, 2018

        Like bauxite clays are formed fron in situ weathering and the red colour may be as a result of the iron content in the clays. Mr. Honeychurch also seems to indicate that the reason for antrim issue is water seepage and erosion. I do not doubt this may be happening but that is a huge mass of soil and if that soil was moved by erosion it would have had to be transported and deposited somewhere. Is the stream cutting through antrim carrying that much load to cause such visible displacement? A geologist depend on visual observations, outcrops of formation boring logs, radiometric dating and other remote sensing tools in addition the previous geologic studies among other tools to make an reasonably accurate scientific conclusion on what is happening in the subsurface. The place is covered with vegetation so deformation and geologic observations are difficult. I have in my posession a geologic map of Dominica that shows possible graben fault in that area which may better explain

      • Shaka Zulu
        May 15, 2018

        the subsidence. There are several other possible faults that run near that area. I do not doubt that Mr. Honeychurch has good intentions but we have to make sure opinions are not presented as facts especially for someone with his stature. Unless a thorough geotechnical assessment is done in that area with proper scientific data collection and analysis anything about that area is pure speculation. Some may be reasonable but innacurate but must have backup. A simple drive around and observation of the area is not good enough to tell what is happening subsurface.
        Check out the following:
        http://www.charim.net/datamanagement/35
        I will leave it at that. Hopefully readers will want to be informed and do thier own research. Untill then i will wait for the Dr put out his references on geology. If he does not then i will count it as his personal conclusions.

      • Zandoli
        May 15, 2018

        Shaka
        I am also a geolgist by training and I felt the same way as you did. I saw a drawing, but as you said I did not see the scientific data to back up the position.

      • Shaka Zulu
        May 16, 2018

        Zandoli
        The drawing itself is qestionable. I dont know any river in Dominica that sits on silt beds especially for thousands of years. Our rivers are constantly in flood stage and silt is easiest thing to erode. The last time there was a natural dam break on dominica was layou. Any geography student can go there see the depositional evidence. He has not showed how he observed the evidence of the old natural dam break. The problem is since he discredited the engineering work he has to show scientific evidence. I understand his historical perspective but geology is a science and civilization history and earth history is not the same and has different methods of data collection and analysis. Its ok for him to write his opinions but in providing such an explanation he has to show research data or cite other scientific data. Its like me going to a dentist and telling him i need him do open heart surgery on me.

      • Roger Burnett
        May 17, 2018

        In response to Shaka Zulu’s most recent comment:

        The river at Antrim has dammed twice since the placement of spoil from Red Gully. On both occasions the wall of water did considerable damage at Check Hall. Up until Maria a huge log lodged on the river bank indicated the high water mark.

        The river did not dam during Maria because in recent years the collapse and erosion of the high banks has considerably widened the channel.

        Likewise, I am not a geologist. But then again, Leonardo da Vinci was not an engineer and Michelangelo was not an architect.

      • Shaka Zulu
        May 17, 2018

        @ Roger Burnett
        What you indicated justs tell me we either stupid and have a learning problem. You don’t need to be a geologist or engineer to observe nature. If a natural damn busrt once chances are it will happen again. In fact manmade earth dams pose great risk in many places. Anyone with some observation skills can see what is happening. However there are subsurface activities that can only be observed through scientific data collection. All i asked Honeychurch to do is present citations dor his work. Wouldd you take advise for your heart condition from a dentist? Or your mechanic?
        Leonardo de vinci was an engineer and Michelangelo was an architect/painter they both had talent skills and unique abilities. They did not just born and start doing stuff. They still had trial and error. However there is no magic in determination of subsurface conditions. You have to collect data and make an analysis based on experience (trial and error) or education.

  36. anonymous2
    May 15, 2018

    Thank God for Honychurch. He knows his stuff, especially when it comes to DA. Maybe he can suggest another place to put the cross country road. It doesn’t look like there is any hope with the current Imperial Hwy as it is essentially built on a narrow edge. The other route is through Jimmit.

  37. winston warrington
    May 15, 2018

    This information is vital to design and construction.

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