Bitcoin Citadels Poll

[gwestcot]

I am a land surveyor by profession and current events led me to looking for a suitable citadel to be free and to lay low. I discovered, by looking through open source bathymetric data, an area that is highly suitable for dredging up an artificial island and also not in any national EEZ. Basically, the area is extremely shallow but also located in international waters. At any rate, below is a link to a survey that will aid me in planning for the project to create a citadel for bitcoiners and even altcoiners alike. If you are interested then please spread the survey link so that I can get the maximum amount of feedback.

https://www.surveymonkey.com/r/6DJQRPC

[Poker Player]

I have two doubts about what you are raising.

The first is whether one can effectively "appropriate" what are international waters and establish an artificial island and a system of government there. I doubt it, because if that were the case, many countries could expand their territories by doing the same.

The other is about the sustainability of creating an artificial island there. We would have to transport everything on a regular basis. Starting with drinking water.

I don't see it.

[gwestcot]

I have two doubts about what you are raising.

The first is whether one can effectively "appropriate" what are international waters and establish an artificial island and a system of government there. I doubt it, because if that were the case, many countries could expand their territories by doing the same.

The other is about the sustainability of creating an artificial island there. We would have to transport everything on a regular basis. Starting with drinking water.

I don't see it.

Pertaining to your first comment that is indeed permitted under UNCLOS if you are talking about international law. However, under international law the artificial island will not get territorial waters which are 12 nmi or an EEZ which is 200 nmi. Don't quote me on this but I believe these created island would only get 500m of protection from the baseline. That being said, international law does not have any real enforcement arm and the only thing that would matter would be recognition from other nations.

As far as drinking water is concerned, You could establish rain water collection systems on every roof which would likely be more than sufficient for personal consumption. However, I am guessing some level of desalination would also be needed for commercial interests. Additionally, it is very likely that a fresh water reservoir would begin to form under the island as seen on one of China's artificial island in the South China Sea. Look at the source below.

https://www.scmp.com/news/china/science/article/3090761/freshwater-reservoir-found-one-beijings-artificial-islands-south

[stompix]

Pertaining to your first comment that is indeed permitted under UNCLOS if you are talking about international law. However, under international law the artificial island will not get territorial waters which are 12 nmi or an EEZ which is 200 nmi. Don't quote me on this but I believe these created island would only get 500m of protection from the baseline. T

After what happened to Elwar, it's not a case about distance but about from who you are 12 miles away..
While I doubt the danish navy will start firing cruise missiles at you, Thailand we already know how it deals with this and I think both cases like Somalia or Iran would be clear no.

But that aside, the biggest problem would be to convince poeple to move there, and the reasons are pretty simple, why would somebody leave their country for this? All these types of projects have attracted millions of tweets and thumbs up but almost no clients.
Just because it's a country or small nation full of poeple who like Bitcoin it doesn't mean it will be heaven on Earth, you can see even in this forum we're not all friends, we have different opinions, we have different views on the economy or society, not even mentioning our language, culture and many other small things that would lead to poeple calling it Babel's Island.

[tertius993]

I will be brief: it’s a bonkers idea.

[SFR10]

a suitable citadel to be free and to lay low.
~Snipped~
to create a citadel for bitcoiners and even altcoiners alike.

Personally, if such a place already existed, occasionally I might visit it but I would never relocate to a place that "can't" achieve its main objectives! Most bitcoiners ^{[and altcoiners]} rightly have trust issues and I don't think they'd prefer to permanently move to a place that might expose them to other potential risks, that are present within the community ^{[looks can be deceiving and being inside a certain circle, doesn't guarantee that you'd be completely safe]}!

[South Park]

You are talking about forming your own micronation and as other similar experiments have shown before, this is bound to fail, if you want to be free and lay low I cannot think of a worst way to do it than this, by doing this you will immediately become a target of every single country of the world, after all forming a country is not something that happens in such arbitrary fashion, and even if you think you got all your bases covered and you think you can do it there is nothing stopping the governments to change those same laws and regulations to give themselves permission to appropriate any land you happen to bring to the surface.

[gwestcot]

You are talking about forming your own micronation and as other similar experiments have shown before, this is bound to fail, if you want to be free and lay low I cannot think of a worst way to do it than this, by doing this you will immediately become a target of every single country of the world, after all forming a country is not something that happens in such arbitrary fashion, and even if you think you got all your bases covered and you think you can do it there is nothing stopping the governments to change those same laws and regulations to give themselves permission to appropriate any land you happen to bring to the surface.

All other attempts were inside the territorial waters of another nation. The most prominent example was probably Minerva Atolls and Tonga. This is dissimilar to that right from the get go. It is 600 miles away from the next closest EEZ. Laying low is not being free it is simply hiding. That is the life of a rat and they will come for you with the full power of the intelligence community and military when the time comes. The narrative within a country is a lot different than if one is outside said country. To me, the worst thing to do is to "lay low" in a western country.

I will be brief: it’s a bonkers idea.

Well history is littered with successes that were bonkers ideas. From an engineering perspective, the person that built the Florida Keys Overseas Railroad was thought to be certifiably insane but the task was accomplished. I suppose it did get partially destroyed during a very strong and almost unprecedented hurricane but the point still stands.

Pertaining to your first comment that is indeed permitted under UNCLOS if you are talking about international law. However, under international law the artificial island will not get territorial waters which are 12 nmi or an EEZ which is 200 nmi. Don't quote me on this but I believe these created island would only get 500m of protection from the baseline. T

After what happened to Elwar, it's not a case about distance but about from who you are 12 miles away..
While I doubt the danish navy will start firing cruise missiles at you, Thailand we already know how it deals with this and I think both cases like Somalia or Iran would be clear no.

But that aside, the biggest problem would be to convince poeple to move there, and the reasons are pretty simple, why would somebody leave their country for this? All these types of projects have attracted millions of tweets and thumbs up but almost no clients.
Just because it's a country or small nation full of poeple who like Bitcoin it doesn't mean it will be heaven on Earth, you can see even in this forum we're not all friends, we have different opinions, we have different views on the economy or society, not even mentioning our language, culture and many other small things that would lead to poeple calling it Babel's Island.

I would like to think there are many people willing to venture into the unknown. It is definitely fraught with risk but the payout is immense. Besides, I am not entirely naïve in the thinking that bitcoiners uniting makes some utopian society. I just think the current ones are too broken and starting anew with a stronger foundation would have greater chances of success than staying within the rotting legacy system. But yes this location is not close to any world power at all. It is exceedingly remote and is not near any fault lines, volcanoes, or storm prone areas. I have already requested a quote for satellite bathymetric data and it is actually very cheap. Preliminary findings are that there are potentially areas that are already sticking above the ocean. However, satellite bathymetry is not terrible accurate so my guess is that it is a meter or two below the ocean because it is hard for me to believe that any piece of land sticking out is unclaimed in this day and age.    

[tertius993]

I will be brief: it’s a bonkers idea.

Well history is littered with successes that were bonkers ideas. From an engineering perspective, the person that built the Florida Keys Overseas Railroad was thought to be certifiably insane but the task was accomplished. I suppose it did get partially destroyed during a very strong and almost unprecedented hurricane but the point still stands.

Well I certainly admire tenacity … though you pick an unusual example of a “success” … wasn’t the railway company already bankrupt at the time much of the Overseas Railroad was destroyed by the hurricane you mention? Perhaps a not wholly encouraging comparison to draw?

[gwestcot]

I will be brief: it’s a bonkers idea.

Well history is littered with successes that were bonkers ideas. From an engineering perspective, the person that built the Florida Keys Overseas Railroad was thought to be certifiably insane but the task was accomplished. I suppose it did get partially destroyed during a very strong and almost unprecedented hurricane but the point still stands.

Well I certainly admire tenacity … though you pick an unusual example of a “success” … wasn’t the railway company already bankrupt at the time much of the Overseas Railroad was destroyed by the hurricane you mention? Perhaps a not wholly encouraging comparison to draw?

Haha not exactly the point I was trying to make. The point is that people thought it was impossible from an engineering perspective but now some of it serves as the highway to the Florida Keys. What many think is impossible is simply something that hasn't been done yet. But honestly, the engineering side of this might actually be easier than I at first thought. The other aspects may prove somewhat more challenging.

[stompix]

Besides, I am not entirely naïve in the thinking that bitcoiners uniting makes some utopian society. I just think the current ones are too broken and starting anew with a stronger foundation would have greater chances of success than staying within the rotting legacy system.

Stronger foundation..
Take a look at the Bitcoin foundation and what happened and who its members were, just because you replace the current governing body with a brand new one that is full of revolutionary ideas it means nothing, how many revolutions were triggered by the same "unfair" and "rotten" system have ended costing more lives than the previous? And you're going to build it with the same people, the poeple who have been actually been advantaged by the current system since the ones who will afford to move there are the ones who could afford things previously too.

Sorry , but an utopia is an utopia

I would like to think there are many people willing to venture into the unknown. It is definitely fraught with risk but the payout is immense.

Rather the bill is immense, let's forget about the island itself and the whole infrastructure you're going to have to build.
Everything that is at a small scale is losing money economically when providing basic services, for example, you're going to have to build hospitals with every doctor for every major disease otherwise it would make no sense, right, for everything you need to take the plane and fly 1000 km to receive treatment. And with a small community of <25 000 you won't be able to do it, neither will you manage to get the education right, and a lot of other things, no small community will ever be independent, you can see this in small towns that rely completely on the major metropolis close by for everything.

And the payout? Payout in what?
Quantify this payout in anything cause I'm really curious about it.

But yes this location is not close to any world power at all. It is exceedingly remote and is not near any fault lines, volcanoes, or storm prone areas.

Hmm, so we delete locations near fault lines, we cut seas close to US, EU, IN, CN, we stay between the tropics lines, we ditch the Atlantic area, so what is left is the western Indian ocean or Polynesia. For the second I don't see anyone letting you build something there, not with the current geopolitics and all the eco-movement drama. If you're wondering why not, simply, because nobody wants to have an island popping out of nowhere that can be taken over by a foreign power and drive a wedge on the current influence map.

[gwestcot]

Besides, I am not entirely naïve in the thinking that bitcoiners uniting makes some utopian society. I just think the current ones are too broken and starting anew with a stronger foundation would have greater chances of success than staying within the rotting legacy system.

Stronger foundation..
Take a look at the Bitcoin foundation and what happened and who its members were, just because you replace the current governing body with a brand new one that is full of revolutionary ideas it means nothing, how many revolutions were triggered by the same "unfair" and "rotten" system have ended costing more lives than the previous? And you're going to build it with the same people, the poeple who have been actually been advantaged by the current system since the ones who will afford to move there are the ones who could afford things previously too.

Sorry , but an utopia is an utopia

I would like to think there are many people willing to venture into the unknown. It is definitely fraught with risk but the payout is immense.

Rather the bill is immense, let's forget about the island itself and the whole infrastructure you're going to have to build.
Everything that is at a small scale is losing money economically when providing basic services, for example, you're going to have to build hospitals with every doctor for every major disease otherwise it would make no sense, right, for everything you need to take the plane and fly 1000 km to receive treatment. And with a small community of <25 000 you won't be able to do it, neither will you manage to get the education right, and a lot of other things, no small community will ever be independent, you can see this in small towns that rely completely on the major metropolis close by for everything.

And the payout? Payout in what?
Quantify this payout in anything cause I'm really curious about it.

But yes this location is not close to any world power at all. It is exceedingly remote and is not near any fault lines, volcanoes, or storm prone areas.

Hmm, so we delete locations near fault lines, we cut seas close to US, EU, IN, CN, we stay between the tropics lines, we ditch the Atlantic area, so what is left is the western Indian ocean or Polynesia. For the second I don't see anyone letting you build something there, not with the current geopolitics and all the eco-movement drama. If you're wondering why not, simply, because nobody wants to have an island popping out of nowhere that can be taken over by a foreign power and drive a wedge on the current influence map.

Well you fill in the discovered vulnerabilities in the structure of existing governments that cannot now be patched due to political reasons. That is what I meant in regards to building a stronger foundation. However, there may be some yet unforeseen vulnerabilities in a particular constitutional structure so sure it could, with enough time, end up in the same place as today. That being said, that is basically the summation of the entirety of human history with human civilization repeating the same basic patterns over and over.

Small communities or nations can also do some things that don't necessarily scale at large. An example of this would be Singapore and a few others I am sure we can create a short list of. I imagine tourism, banking, bitcoin mining are all possible industries if infrastructure is planned properly. I haven't gotten to the comprehensive list of the cost of infrastructure on the island itself but from preliminary calculations and research I believe that the dredging would likely be more expensive than the infrastructure itself. However, my idea is that everything would be circular and self sufficient in nature. Basically, near zero waste and life essential items such as water and food are mostly created or grown on the island. This would require a lot of forethought in the zoning and city planning department but it is not outside the realms of possibilities given that we can learn from previous examples of island nations.  Additionally, the area is rather large being 46 square miles in total but I am fairly confident that not all of it would be usable due to some of it being needed for dredging material. It would likely need to be done in 2 year phases due to the enormity of the task. As far as location, you are indeed terribly off base. However, the eco-movement would surely be an inhibiting factor as it is with everything but there are definitely ways to assuage the eco-crazies. Admittedly, I haven't thought much about the geopolitical aspects but I do know it holds absolutely zero strategical advantage to anyone. I have also looked at fishing vessel traffic to the location and it is extremely sparse to the point that only a few ships have visited there in the past year with none staying longer than a few hours. If there is a location it is possible to do this, then it is definitely the one that I have discovered. There is one other area that is possible but it would likely cause a greater uproar given the fishing traffic there. Additionally, there are 8 others in which it is technically possible but are too cold for anyone to really want to live there. Anyways, I enjoy the constructive criticism so please do give me more. Additionally, take the very quick survey above to provide me with a little feedback.

[Slow death]

I will be brief: it’s a bonkers idea.

 

I agree


I see no reason to do such a thing, there are already countries, cities, towns, villages why not focus on convincing these people to use bitcoin as a means of payments and investments? creating an island and taking them away from where they live to go live on an island, I don't see how that could be good. who would leave his house, town, friends to go live on an island just because he's a bitcoin fan if he can be in his house, in his town, with his friends and be using bitcoin?

[gwestcot]

I will be brief: it’s a bonkers idea.

 

I agree


I see no reason to do such a thing, there are already countries, cities, towns, villages why not focus on convincing these people to use bitcoin as a means of payments and investments? creating an island and taking them away from where they live to go live on an island, I don't see how that could be good. who would leave his house, town, friends to go live on an island just because he's a bitcoin fan if he can be in his house, in his town, with his friends and be using bitcoin?

Well because said countries will never give up their power over currency nor will they allow their citizens to live free or truly own anything. I mean we all have opinions and many would not want to come but I am sure there are others that would willingly do so given the current political climate.

[stompix]

Small communities or nations can also do some things that don't necessarily scale at large. An example of this would be Singapore and a few others I am sure we can create a short list of. I imagine tourism, banking, bitcoin mining are all possible industries if infrastructure is planned properly. I haven't gotten to the comprehensive list of the cost of infrastructure on the island itself but from preliminary calculations and research I believe that the dredging would likely be more expensive than the infrastructure itself. However, my idea is that everything would be circular and self sufficient in nature. Basically, near zero waste and life essential items such as water and food are mostly created or grown on the island. This would require a lot of forethought in the zoning and city planning department but it is not outside the realms of possibilities given that we can learn from previous examples of island nations.  

You see, this is the problem, you take only the good parts from everything and ignore the rest.
Singapore is a 6 million poeple nation which is in the middle of all trading routes and it imports 90% of its food and 97% of its energy.

You can't have a thing that is in the middle of nowhere become both a tourist attraction and a banking center, you can't have both tourism and self-sufficiency in food on a small island (both Maldive and Seychelles import tons of it) and you will not get mining going with solar panels.
Not even going to mention the other fact, and this is coming from the black sheep of a 4 generation farmer family you won't get crops from that thing, not with a ton of potassium-rich fertilizer. Of course, it can be done, but the bill is going to be insane.

Btw, what is the cost for dredging enough soil to make a 47 sq miles island, even if we assume what, 1-2 meters deep ocean at that place?

[gwestcot]

Small communities or nations can also do some things that don't necessarily scale at large. An example of this would be Singapore and a few others I am sure we can create a short list of. I imagine tourism, banking, bitcoin mining are all possible industries if infrastructure is planned properly. I haven't gotten to the comprehensive list of the cost of infrastructure on the island itself but from preliminary calculations and research I believe that the dredging would likely be more expensive than the infrastructure itself. However, my idea is that everything would be circular and self sufficient in nature. Basically, near zero waste and life essential items such as water and food are mostly created or grown on the island. This would require a lot of forethought in the zoning and city planning department but it is not outside the realms of possibilities given that we can learn from previous examples of island nations.  

You see, this is the problem, you take only the good parts from everything and ignore the rest.
Singapore is a 6 million poeple nation which is in the middle of all trading routes and it imports 90% of its food and 97% of its energy.

You can't have a thing that is in the middle of nowhere become both a tourist attraction and a banking center, you can't have both tourism and self-sufficiency in food on a small island (both Maldive and Seychelles import tons of it) and you will not get mining going with solar panels.
Not even going to mention the other fact, and this is coming from the black sheep of a 4 generation farmer family you won't get crops from that thing, not with a ton of potassium-rich fertilizer. Of course, it can be done, but the bill is going to be insane.

Btw, what is the cost for dredging enough soil to make a 47 sq miles island, even if we assume what, 1-2 meters deep ocean at that place?

Fine lets use the Cayman Islands as an example then? Are they sufficiently small? You can definitely get mining going with solar panels, a tidal array, wind power, and even biogas would be on the table. You can have strict zoning district for farming, industrial, tourism/shopping, and an urban center. It all really depends on the city planning. I mean the dutch turned the flevopolder into arable farmland and this is nowhere on the scale of that. In all honesty, you would create a zero waste environment in which everything is composted and that does also include the sludge from wastewater treatment. That is the part in which when treated properly you get nutrient rich compost and also biogas to be used for power generation. It is basically a win/win scenario. Modern agricultural practices of using chemical fertilizers are pretty damaging and do nothing to maintain the fertility of the soil in which you are growing in. Also, if you are worried about the salinity of the soil, I have grown food in an almost identical climate and soil conditions as would be present there. I basically just amended the sand with 6-8 inches of compost while adding compost made from my yard, garden, kitchen, and animal waste. After awhile you end up with a very fertile layer of topsoil that is also very well draining. As far as the dredging, it is too early to really say how much material is going to be needed to be dredged. The entire area is about 46 square miles but you wont be able to use it all. Maybe only 29 or so is usable and the rest will be used for material to create the island. The first four phases which would maybe be around 18 square miles in total and would be the most shallow areas. Possibly, with the state of the art process using cofferdams and vibro compaction, you could do it for maybe around a billion dollars. The price tag sounds pretty steep but its not really all that bad in regards to material moved nor price. There have actually been dredging projects that have moved more material than this one. You would likely need to presell lots among other things to get money flowing. Possibly this could be done by first doing a small proof of concept. At any rate, this is all preliminary as I have to wait for the survey to be conducted first before I can even really definitively say its possible on any level.

[aoluain]

Anything is possible with unlimited time and finance. These plans sound very
ambitious and will take many years to impliment.

Creating fertiliser for your own garden is not too much hassle, creating fertile
soil for 18sq miles is another.

Who is going to work on all these projects for the infrastructure, they would
have to be qualified people who know what they are doing.

I could see this working in any existing country, it would essentially be a "commune"
it would be far easier to be off grid, self-sufficient and have a sustainable living setup.

[tertius993]

Small communities or nations can also do some things that don't necessarily scale at large. An example of this would be Singapore and a few others I am sure we can create a short list of. I imagine tourism, banking, bitcoin mining are all possible industries if infrastructure is planned properly. I haven't gotten to the comprehensive list of the cost of infrastructure on the island itself but from preliminary calculations and research I believe that the dredging would likely be more expensive than the infrastructure itself. However, my idea is that everything would be circular and self sufficient in nature. Basically, near zero waste and life essential items such as water and food are mostly created or grown on the island. This would require a lot of forethought in the zoning and city planning department but it is not outside the realms of possibilities given that we can learn from previous examples of island nations.  

You see, this is the problem, you take only the good parts from everything and ignore the rest.
Singapore is a 6 million poeple nation which is in the middle of all trading routes and it imports 90% of its food and 97% of its energy.

You can't have a thing that is in the middle of nowhere become both a tourist attraction and a banking center, you can't have both tourism and self-sufficiency in food on a small island (both Maldive and Seychelles import tons of it) and you will not get mining going with solar panels.
Not even going to mention the other fact, and this is coming from the black sheep of a 4 generation farmer family you won't get crops from that thing, not with a ton of potassium-rich fertilizer. Of course, it can be done, but the bill is going to be insane.

Btw, what is the cost for dredging enough soil to make a 47 sq miles island, even if we assume what, 1-2 meters deep ocean at that place?

Fine lets use the Cayman Islands as an example then? Are they sufficiently small? You can definitely get mining going with solar panels, a tidal array, wind power, and even biogas would be on the table. You can have strict zoning district for farming, industrial, tourism/shopping, and an urban center. It all really depends on the city planning. I mean the dutch turned the flevopolder into arable farmland and this is nowhere on the scale of that. In all honesty, you would create a zero waste environment in which everything is composted and that does also include the sludge from wastewater treatment. That is the part in which when treated properly you get nutrient rich compost and also biogas to be used for power generation. It is basically a win/win scenario. Modern agricultural practices of using chemical fertilizers are pretty damaging and do nothing to maintain the fertility of the soil in which you are growing in. Also, if you are worried about the salinity of the soil, I have grown food in an almost identical climate and soil conditions as would be present there. I basically just amended the sand with 6-8 inches of compost while adding compost made from my yard, garden, kitchen, and animal waste. After awhile you end up with a very fertile layer of topsoil that is also very well draining. As far as the dredging, it is too early to really say how much material is going to be needed to be dredged. The entire area is about 46 square miles but you wont be able to use it all. Maybe only 29 or so is usable and the rest will be used for material to create the island. The first four phases which would maybe be around 18 square miles in total and would be the most shallow areas. Possibly, with the state of the art process using cofferdams and vibro compaction, you could do it for maybe around a billion dollars. The price tag sounds pretty steep but its not really all that bad in regards to material moved nor price. There have actually been dredging projects that have moved more material than this one. You would likely need to presell lots among other things to get money flowing. Possibly this could be done by first doing a small proof of concept. At any rate, this is all preliminary as I have to wait for the survey to be conducted first before I can even really definitively say its possible on any level.

Your biggest problem it seems to me is that the upfront costs are going to be very large and very real, whereas your benefits seem rather vague and ill-defined.

How did you come to your estimate of a billion dollars?  Its hard to find reasonable numbers for this sort of thing but the "World" the artificial islands that Dubai was (are?) building were meant to cover a total of 20 sq miles (rather less than your expected area) with a projected budget of $14billion.  They of course were close to a developed country and were actually part of an already functioning country.

[stompix]

Fine lets use the Cayman Islands as an example then?

Net importer of food, total imports of energy, 100% depended on fossil fuel.

You can definitely get mining going with solar panels, a tidal array, wind power, and even biogas would be on the table

Can you get energy for those at 2.5 cents per kWh, that's the price coal and gas flaring gets you?
Of course, you can get it with government subsidies, but in this case, the government will be you, so more money to throw away.

I mean the dutch turned the flevopolder into arable farmland and this is nowhere on the scale of that.

With the difference that most of those that are suited for agriculture are the podlers and fenlands along some marshes, much of the land used to compact the drained soil was rich land from the estuaries, of which there are a ton, on your land, you won't have one!
I'll not cover the other part about soil since you're talking about home gardening I'm talking about feeding thousands, once you go out of your garden and try to do the same on at least 1ha of land you're going to see the limits of home-brewed compost and no pesticides

Possibly, with the state of the art process using cofferdams and vibro compaction, you could do it for maybe around a billion dollars. The price tag sounds pretty steep but its not really all that bad in regards to material moved nor price.

Seeing how 45m mc3 project costs 1.2 billion and your island would need that only for one foot depth (or height) at 49 square miles I think you've missed a zero

[gwestcot]

Fine lets use the Cayman Islands as an example then?

Net importer of food, total imports of energy, 100% depended on fossil fuel.

You can definitely get mining going with solar panels, a tidal array, wind power, and even biogas would be on the table

Can you get energy for those at 2.5 cents per kWh, that's the price coal and gas flaring gets you?
Of course, you can get it with government subsidies, but in this case, the government will be you, so more money to throw away.

I mean the dutch turned the flevopolder into arable farmland and this is nowhere on the scale of that.

With the difference that most of those that are suited for agriculture are the podlers and fenlands along some marshes, much of the land used to compact the drained soil was rich land from the estuaries, of which there are a ton, on your land, you won't have one!
I'll not cover the other part about soil since you're talking about home gardening I'm talking about feeding thousands, once you go out of your garden and try to do the same on at least 1ha of land you're going to see the limits of home-brewed compost and no pesticides

Possibly, with the state of the art process using cofferdams and vibro compaction, you could do it for maybe around a billion dollars. The price tag sounds pretty steep but its not really all that bad in regards to material moved nor price.

Seeing how 45m mc3 project costs 1.2 billion and your island would need that only for one foot depth (or height) at 49 square miles I think you've missed a zero

I looked up the going rate for the latest large scale dredging projects and 3-4 dollars per cubic meter is right on par. As far as the farming goes, I have done it on a plot the size of 3 hectares which is still larger than the plot of land you are describing. You simply need a fast growing carbon source like bamboo and a steady supply of nitrogen sources such as kitchen waste, manure, garden waste, etc. They all work in relative harmony and as far as pesticides go you can grow neem trees and press the juice out of the seeds to get need oil. Neem oil is an organic pesticide and it has always done the trick for my fruit trees and vegetables. It simply requires farming a different way but yes mega farms would likely not be feasible. Fair point on the polders being rich land but having poor quality land can be remedied with time and good practices. Container ships can carry in compost/top soil if a seller is located. This is more of a question of money than it is about feasibility. Anything is really possible with enough determination, ingenuity, and creativity.