One of Singapore's iconic tourist destinations is the Marina Bay.
Go there to see the stunning Marina Bay Sands casino, ogle the Merlion,
shop expensive goodies, and more. I have done all that and it is a blast.
But something most tourists are probably not aware of as they snap selfies with the
casino in the background is that they are standing at the edges of Singapore's 15th
and largest freshwater reservoir.
In this video, we are going to look at how that came to be.
How the Singaporean government dammed the entire Marina Bay.
And how their experience might inform other countries trying to beef up their water supply.
The Marina Bay is located in Singapore’s Central Area and has been styled to be its new downtown.
This central area has been around since Singapore's earliest years
and used to host wet markets and bazaars alike.
Starting in 1969, the government embarked on
clearing out the space and adding 360 hectares of waterfront land.
They intended to create a venue for staging international water events and celebrations.
On top of this prime waterfront land, the government began adding hotels, business offices,
and convention areas. The vision would be that it could serve as a 24/7 live-work-play area.
Water flows into the bay from upstream rivers like the Singapore River, the Geylang River,
and Kallang River. The extensive land reclamation redirected the rivers' flow
so that they no longer empty directly into the ocean.
In a previous video, I went into detail about Singapore's 50 year march towards
water independence. Part of that strategy involved
the expansion of local catchments for the country to store its freshwater.
Of course, being a small island, opportunities to build such reservoirs are limited.
In 1987, Minister Mentor Lee Kuan Yew had a proposal for the Marina Bay:
> "In 20 years, it is possible that there could be breakthroughs in technology,
both antipollution and filtration. Then we can dam up or put a barrage at the mouth of the Marina,
the neck that joins the sea. And we will have a huge freshwater lake".
In order to do this, the country had to first barricade the entire Marina Bay to keep the
freshwater from flowing into the South Chinese Sea. Once that dam is complete,
then the bay can slowly be transitioned from a body of saltwater to freshwater.
Singapore is subject to large torrential rains. That water tends to come fast and unpredictably.
Because all the rivers now flow into the Marina Bay,
a dam would rapidly need to open up to release stormwater into the open ocean
to prevent water from flooding into the surrounding low lying area.
Minister Mentor Lee's vision would be accomplished with the $250 million SGD Marina Barrage Project.
The Barrage spans the entire Marina Channel, roughly 350 meters wide.
Constructions began in 2005 and was completed in two phases over three years.
The dam is made up of multiple components. First is the barrage itself. It has nine crest gates
and a six meter wide pedestrian bridge on top of it. Each of the gates are nearly a hundred feet
or 29.75 meters wide. Individually they weigh nearly 70 tons. Or almost as much as your mom.
The other components help the dam do its job. There is a drainage pumping station,
a lift for taking boats in and out to sea, a hydroelectric power plant, and, of course,
a visitor's center with a green roof.
At the time of their installation, the pumps in the pumping station were the biggest in the world.
Each capable of emptying an entire Olympic sized swimming pool in a minute.
They are to engage to remove stormwater during high tide.
The first phase began with the construction of a cofferdam and four of the nine gates.
A cofferdam is a watertight enclosure built onto the sea floor that allows for construction
under the waterline. The Marina Barrage cofferdam is itself pretty cool achievement.
Double-walled and 40 feet or 12 meters wide, the inside was filled with sand.
The barrage itself was built on top of a foundation of 850 bored piles.
Each pile are four feet or 1.5 meters long and went up to 240 feet or 74 meters deep. The
cofferdam itself had to have sheetpiles drilled a hundred feet or 31 meters deep into the bedrock.
Installing the gates was pretty impressive. Each of the 70 ton gates have to be lifted
from a crane barge floating outside the cofferdam into position between the dam piers.
The precision of the placement has to be accurate to 2 millimeters.
As Phase 1 completed, a 100-meter section of that channel was left open for stormwater and ships to
pass through. Upon completion, the cofferdam was removed and the gates left in an open position.
The second phase saw a second cofferdam for the completion of the last five gates as well
as the installation of the pedestrian bridge's nine segments on top of the barrage. One of the
world's biggest cranes had to be commissioned to lift and carry the bridge's segments into place.
With the barrage's completion in 2008,
the reservoir was separated from the ocean but held a mix of salt and freshwater.
The reservoir needed to be desalinized. This process happened naturally over a span of 15
months as rainwater flowed into the bay and salty water was flushed out into the ocean.
The Marina Bay today provides up to 10% of Singapore’s water supply.
Thus far it has accomplished many of the goals the government had in mind for it. But
it is worth noting some of the consequences and concerns associated with barricading Marina Bay.
The first has to do with the cleanliness of the water. A lot of reservoirs are located
far away from population centers for a good reason: Humans are dirty, disgusting creatures.
The Marina Bay is Singapore's biggest reservoir and the only one located right in a downtown
urban area. It is inevitable that trash and waste will wash right into the reservoir.
The Singapore government asserts that the reservoir's water is cleaned daily.
Water samples and analyses though have found perfluorochemicals in the reservoir's sediments
and waters. These chemicals are used to make coatings resistant to oil, heat, or grease. The
long term health consequences of being exposed to these chemicals in high levels are unclear.
The second major concern has to do with the environment. As an estuary zone where
salt and fresh water meet, the Marina has provided a home for several animal species.
Fish traps set up during the dam's construction found 138
fish species from 57 families. Only 25 of them can survive in freshwater
without access to the sea. Another 17 can survive but require access to the sea for breeding.
Of course, I am not saying that we should forego the freshwater benefits
of Singapore's largest reservoir solely for the sake of a fish.
The tradeoff in Singapore is pretty cut and dry. But for other countries around the world with
different environmental, wildlife, and fishing conditions, it is something to think about.
Not every reservoir has to be built out of a massive,
towering dam in a gorge. Hong Kong's Plover Cove and Singapore's Marina Bay demonstrate
the possibility of making coastal reservoirs by barricading estuaries and coastlines.
As other countries find themselves more water challenged due to the effects of
global climate change, locations for traditional lake-style reservoirs
are few and far between. For countries finding themselves in such situations,
it might be prudent to look at coastal reservoirs as an alternative structure.
The Marina Barrage is a tourist attraction, a valuable piece of
infrastructure and an engineering marvel. I hope to be able to visit it one day.