Retaining Walls With Tyres

BY pure coincidence I read an article on the Government of St Lucia’s website which spoke of efforts of the SSDF to teach local tradesmen in the construction of retaining walls using scrap tyres. I found it heartening and disheartening, heartening because of its novelty and disheartening because the SSDF never saw it fit to engage the local Association of Professional Engineers in this project.

Engineers from the Conseil Generale of Martinique in collaboration with the Saint Lucia Social Development Fund (SSDF) held presentations for tradesmen that demonstrated how to use scrap tires for slope reinforcement..

The report said that SSDF Director Joachim Henry applauded the initiative and commented as follows:

“Today the engineers will demonstrate to workers from the community how to attach the tires to construct a retaining wall. The French are interested in our approach and our ability to conduct effective community mobilization. During this week we hope to see the construction of a retaining wall.”

The stated aim is to build two retaining walls using a total of 10,000 scrap tyres and the report went on to say that the utilization of scrap tyres as reinforcement, especially for slope repairs, is particularly useful to countries like Saint Lucia, where slope failures (landslides) are common and scrap tires are abundant. The presentation on the construction of retaining walls using recycled tyres was held at the Marigot Secondary School.

One must applaud the SSDF for this initiative as I believe that the Mount Deglos we have created with scrap tyres at the landfill can be placed to use. The simplicity of the construction allows the engagement of non-skilled labour and can prove to be an effective employment generator.

I have long lamented that our bright sons and daughters of Saint Lucia have not been used in effective research of relevance to our society. We have hundreds of professionals who have done their Masters and PhD degrees on subject matter that is completely irrelevant to our society. The government must begin to influence this new approach. We cannot be funding a student’s education and the research that is being done is on the effect of snow on structures, or frost heave. We must begin to see research as important to our development.

I believe that there are exciting possibilities for the use of scrap tyres in engineering structures. I am of the opinion that they can be combined with geogrids to create effective earth retaining systems. I am also of the opinion that a mat of scrap tyres with one side wall cut and effectively tied with pvc coated galvanized wire and encased with mass concrete can become a sound sea defence structure. There are exciting possibilities, and the research must begin now.

It would be interesting to find out the level of involvement of the Ministry of Infrastructure in this SSDF Initiative and to also observe the readiness to accept the technology within the activities of the Ministry. We have to begin to be bold and try new ideas and concepts.

I recently went down the West Coast Road and observed some experiments that were done in 1992 – 1995, during my stint as Chief Engineer and the resultant effects. Firstly, during the construction of the West Coast Road the Ministry supported experiments in Bio-Engineering done by Dr. Helen Clarke. One such experiment looked at the use of the Vewtive grass. You would observe that on the side of the concrete drain there are some rocks and vetiver grass planted. The Vewtive due to its very deep fibrous roots becomes an effective retainer of soil and filter. This has reduced significantly the blockage of the drains from eroded soil.

The second experiment looked at the use of stress absorbing membranes ( SAM) on asphalt layers to reduce the oxidation of the asphalt. We added a material from Australia with bitumen and applied it as a surface dressing on the road. The idea is that this layer will become a sacrificial layer in the oxidation process and extend the life of the road. This saved certain sections of the West Coast Road.

We must begin to see the importance of research to our development. Economists cannot continue to present economic models that have failed us for the last 50 years. If in the 1960’s Calixte George, Francis Leonce and the host of other leaders in our agricultural sector could see the importance of home grown research, why has that thirst died?

Our solutions must be home grown. We have developed a tourism industry as a pillar of our economy which has no causal relationship to increases in arrivals. So we boast and shout from the mountain top of increases in tourist arrivals and hang our heads and mutter that the economy is in decline. The increases are definitely not in the hotels as Cotton Bay is empty, Smuggler’s has been demolished, and several other hotels are crying about low occupancy. Just maybe they are in private villas where the government gets nothing as revenue.

The only time that there is an impact on our economy is during the construction of the hotel, we need to do the research to see why the tourism sector has had so little effect on the economy despite the huge concessions and money poured into it.