Posted on May 3, 2023
A ‘rainbow’ of sand shot out from the MV Ham316 into Kingstown Bay on Tuesday morning at 10:45, signalling the beginning of a process to reclaim land on which a new EC$458.4 million container port will be built in Kingstown.
And, over the next seven weeks, a total of 1.17 million cubic metres of sand will be taken from the seabed off the south east coast of St Vincent, between Milligan Cay and Argyle. The material will be transported to Kingstown, then dumped on to the footprint of the project.
He said Canadian construction firm Aecon was given permission to begin dredging on Monday, April 24, the same day they signed an agreement to pay the state EC$20 million for the material.
Douglas highlighted that under the Port Modernization Project, which is the second largest capital project in the history of St Vincent and the Grenadines, the government has been “technically able to accrue savings” amounting to EC $20 million under the construction contract.
“This is important as persons always concern themselves about project cost overruns, but rarely you hear of a project accruing significant saving during its implementation.”
But the dredging at Argyle has raised concerns among some citizens, including Dr Andrew Simmons, a Vincentian climate change and sustainable development consultant.
Simmons, in posts made on Facebook said residents of the communities along the coast have not been consulted about the project and feel the dredging would have a detrimental effect on their communities.
“The boat was there yesterday and again this morning raking the seabed of the limited sand that remains after forty years of sand mining on the beaches of Stubbs, Diamond and Brighton.
“It seems as though no consideration was given to whether the dredging of the seabed will severely impact the EC$1.5 billion Argyle International Airport, the 1000s of fisherfolks and their families who fish in the area to eke out a living, and the over 25,000 residents from Brighton to Biabou who are now being exposed to the impact of storms, sea level rise and tsunamis,” Simmons said on Tuesday.
But assistant project manager Douglas, who holds a Bachelor’s degree in civil with environmental engineering and a Master’s degree in project management told SEARCHLIGHT that the key issues of livelihoods, impact on infrastructure, feasibility and alternative sources have been addressed through scientific investigation, independent studies and supervised studies.
He said the conclusion of the studies is that the approved dredge area is a barren seabed, the livelihoods of fishermen will not be impacted, and the dredging will not affect wave size or patterns even under extreme weather circumstances.
HOW WAS THE DREDGE SITE CHOSEN?
The Argyle site was chosen after considering six locations around the country, Douglas said, with some locations being eliminated because they did not have the conditions for optimal operation of the dredger vessel, or because the size of the sand grain found there fell outside the required range.
“To the untrained eye, any material that looks like sand, is sand. But on the science of it, sand falls within a certain spectrum when you sift,” the engineer said.
He also explained that in order to facilitate the operation of a dredger vessel, there must be an abundant and uniform resource, a seabed that is relatively flat and water depths within a certain range to make dredging feasible.
The area between Milligan Cay and Argyle that has been approved for dredging contains an estimated volume of 10 million cubic metres of sand, Douglas said. He explained that the material that settles there originates from the Rabacca area and is swept south by a current that comes down from the north.
“… As you come down the east coast, you have a situation where the finer materials will travel further. By the time you get to Argyle, the material that is settling out in Argyle is a uniform deposit of sand, and that makes it feasible for dredging.”
He said navigational charts show that there are significant sand deposits at Argyle and in one other area, to the extent that sand waves are forming on the seabed.
“We are only removing 10 per cent of the total estimated material deposited in the vicinity, so 90 per cent remains…, the resource [is] not being over exploited.”
The dredging will take place at a distance of 750 metres from the shore, at a depth of 15 metres.
When the vessel gets to Kingstown, the bottom of the vessel will open to allow the sand to drop out into the footprint of the project. During each trip, the dredger will transport between 3,500 and 5,000 cubic metres of sand, Douglas said.
The other location where navigational charts show significant sand deposits is at Blue Lagoon, but this site was rejected because it is located within the South Coast Marine Park, a protected marine conservation area since 1987.
Douglas said in addition to publicly available information like navigational charts and earlier studies, the contractor, the government and independent consultant Selhorn commissioned other technical studies.
HOW WILL THE LIVELIHOOD OF FISHERFOLK BE AFFECTED?
The civil engineer said the results of a multi-beam bathymetric survey done to map a sonar image of the seafloor concluded that there is an absence of coral, rocks and seagrass within the dredge zone.
“If you can’t have extended sea grass, you can’t have coral, you don’t have rock ledges, quite naturally, … any fish that you catch in that area is basically a fish that is passing through, which we refer to as transient species.
“If you do not have the ecosystem to facilitate the habitat to allow for them to have shelter and protection and … a food source, … then you don’t have a thriving fishing ground.”
Douglas said when the fisherfolk who claimed to use the location were taken to the site, they did not “stitch together a compelling story” to prove that where they fish is 750 metres from the shoreline, at water depths greater than 15 metres, which is where the dredging is to occur.
“ …We also observed the location for fishing activity, which is a prudent step to do, and the observations over a period of time show- you would see boats passing through, but definitely not standing, stable to set their fish pots, etc.”
He said based on the bathymetric survey and their observations, it was concluded that “the livelihood of the fishermen will not be impacted because whatever fish they may catch there, is transient and transiency will not stop. But it certainly it is not a primary fish location.”
Douglas said consultations were also done with fisherfolk, of which the one at Calliaqua was “explosive”, but internal consultations were also done with the fisheries department … and local governmental stakeholders, who agree that the area is a barren seabed.
He noted that the Environmental and Social Impact Assessment (ESIA) done of that area in 2008, prior to the construction of the Argyle International Airport described the biological diversity in the area as “insignificant” and said the area “suffers from a significant land based pollution”. The Argyle ESIA also said that the fishing biodiversity increases north of the Yambou River, which is beyond the area approved for dredging.
IMPACT OF DREDGING ON THE NEAR SHORE, INCLUDING THE AIA
Douglas said importantly, the project implementation unit commissioned an independent report through the Hamburg University of Technology in collaboration with Wasserbau Institute of River and Coastal Engineering “to look at specifically the near shore impact of the dredging in the vicinity of Argyle, … meaning the impact on beaches, the impact on wave height, the impact on the sedimentology and the most importantly, the impact on the airport, because it’s important that we know we’re not going to impact the infrastructure.
“…The conclusions of that report state that the dredging scheme will not change the wave conditions at the coast significantly…. It also will not change the actual sediment transport conditions, and it also will not change the … forces that a wave will exert on the airport.”
He explained that the reason why the wave forces will not change is because the average height of significant waves in the area is around 4.2 metres, while the dredging will be at a depth of at least 15 metres.
Douglas explained that the fact that the dredging is occurring at a depth of over three times the height of the waves is critical, because … once the waves do not touch the bottom of the seabed, there will be no impact on sedimentology.
“That’s why fishes survive during storms. They go to a depth where they do not get all of this turmoil from the rolling motion of the surface waves. So they just sink deeper. So our operation is being done at a water depth where it is over three times the height of the significant waves that pass through the location in Brighton.
“As a consequence of the depths, you’re not going to have issue with the sediment transport. You are not going to have issue of the beach erosion, because if the waves are not touching the bottom, the waves are not moving any sand from out the dredge zone to carry it on to the beach.”
Douglas also made the point that the approved dredging area spans from Milligan Cay up towards the Rawacou Recreational Park, a distance of 750 metres.
“If we are to use the entire area, you’re going to be removing half metre (1.5 feet) of material … over a large area, at a location where the waves do not touch the bottom.”
He said the Hamburg/Wasserbau study also concludes that the dredging will not impact the force with which the waves hit the shore infrastructure, as for the wave energy to increase, the wave heights will have to increase, because the wave height is what carries the energy.
WILL THE DREDGING WORSEN IMPACT OF EXTREME WEATHER?
Douglas said the scientists from Germany created a computer model which rerouted Hurricane Irma over St Vincent to see what impact the hurricane would have after the dredging scheme was implemented.
Hurricane Irma was a category five hurricane which passed over the Caribbean in 2017, resulting in severe infrastructure damage and loss of lives.
He said again, the conclusion was that, even under extreme hurricane conditions, removing upwards of two metres of material from within the dredge zone will not create any significant increases to the wave heights.
“…Under normal circumstances, there should be no issue, and under extreme weather circumstances, they should be no issue,” Douglas said.
BANNING OF SAND MINING AND EROSION OF SAND
The Hamburg/Wasserbau study also reviewed a report that was done by USAID in September 2010 which justified the banning of sand mining in the Brighton/Diamond area.
Douglas said the report gives all of the coastal parameters at the time when the authorities were contemplating banning sand mining along the south east coast of St Vincent.
“Fundamentally, one of the principal reasons for banning the sand mining in the Brighton area had not so much to do with the fact that they were removing sand from the beach, but more to do with the fact that they would have destroyed the [sand] dunes and the destruction of the dunes resulted in a change in the wind pattern of the Brighton Bay area.
“…But our dredging scheme is not changing the impact on wind and it is not changing the impact on waves,” Douglas assured.
“So that’s key because it means that the report from the German university thoroughly looked at the dynamics that existed at the location in the vicinity of Brighton, Diamond and Stubbs to factor that into the modelling and processes.”
IS THE MATERIAL SUITABLE?
Douglas said the sand from the Argyle area was found to be adequate for the purpose of reclamation, and importantly, meets compactibility requirements.
“When you move the material from Argyle and you place it in Kingstown, in order for you to start building on it, you need to compact that material and the seabed in Kingstown to a density that will make it safe for construction, considering all technical circumstances.”
He said the laboratories did multiple relevant tests and found that the sand was “suitable for the purpose”.
HOW LONG WILL IT TAKE FOR THE SAND TO BE REGENERATED?
The minimum replenishment time for the vicinity is three years, but this will be dependent on nothing unforeseen happening.
“So if we have, for example, huge rainfall during the rainy season, and a large volume of material is washed down from the mountain, you can find the three years becoming less, because the material will end up at Rabacca and more material will come down and deposit out at Argyle and therefore replenish much quicker.
“It can also take a little longer, again, depending on circumstances, because if you have a hurricane, maybe it can create some other issues. But the fact of the matter is a minimum of three years.”
Douglas however said even if it does not replenish in this time, only 10 per cent of the total estimated material that has been deposited there will be removed.
OTHER SOCIAL IMPACTS
The assistant project manager said noise from the dredger vessel is not perceptible onshore because of the setback of 750 metres of the dredging zone from the coastal residents of Brighton/Diamond.
Additionally, Douglas said, “… you’re not going to have traffic impact and an infrastructure impact in terms of trucks mashing up the road and so on. And all the dust and noise that may be associated with that, even in Kingstown, the process of placement of the material on site.”
The civil engineer said due diligence has been done in relation to the project.
“We have exercised our technical expertise and issued the relevant advice with regard to how we see this process going forward and the government through Cabinet was satisfied that it is indeed feasible and we’re now moving ahead.”