We report on our fair share of unique pool concepts at Pool Magazine. None so far this year, with the exception of possibly the Sky Pool in London, has managed to capture people’s imagination the way this project has. Plus Pool is a unique floating pool concept design that is shaped like a plus sign (+). The project has been discussed for a long time. For the past few months photos have of the pool concept have begun circulating on social media once again. After years and years of pushback from the city, the Plus Pool project finally got the green light. The 285,000 gallon floating pool will have a permanent address in the East River.

The Plus Pool Design Team

The minimalist pool design is the brainchild of four designers. Dong-Ping Wong and Oana Stanescu of the architecture firm Family and Archie Lee Coates IV and Jeff Franklin of the design firm PlayLab. The group originally conceived of the idea for Plus Pool back in 2010.

Wong, a New York state licensed architect with a Masters Degree in Architecture from Columbia University, first conceived of the project with his friends one hot summer night roughly ten years ago.

Pool Magazine had the chance to catch up with Dong Ping Wong, founder of the architectural firm FOOD New York and one of the lead designers behind the Plus Pool. We had a laundry list of questions for him from folks in the pool industry that wanted to know more about this project. Particularly, folks like Dave Penton of Ask The Masters, expressed interest in the filtration technology and how pool designers intend to safely filter a million gallons of water from the East River each day.

The floating pool concept is an Olympic sized pool at least in length explained Wong. The design is shaped like a plus which gave it the moniker “Plus Pool”.

Let’s Dive In: Plus Pool Fast Facts

• Total Length & Width: 217 feet
• Total Depth: 11′ to 6″
• Total Area: 29,700 sqf
• Pool Volume: 285,500 gallons
• Pool Length: 164′ – 1 (Olympic)
• Pool Width: 32′ – 8 (4 Lanes)
• Pool Depth: 5′ to 0″
• Max Capacity: 300 people

“Basically the whole idea is to find a way to swim in natural water around New York City,” said Wong, “In this case East River water, which as you would imagine is not what you would think of as the cleanest water. So how could we swim in that safely?” asked Wong, a question we wanted to know the answer to as well.

The question itself has many skeptics wondering how designers plan to pull it off. Wong explained the basic premise behind what he plans to do. “In concept, the filtration system is a big strainer. Filtration is built into the walls of the pools. Water literally flows through the walls of the pool itself into the basin.” said Wong.

“In normal operation we expect to filter over a million gallons of water a day, but in comparison to the entire volume of the East River it’s really a drop in the bucket.” continued Wong.

Plus Pool Filtration

“The filtration is a combination of technologies we’ve already found in place for other uses,” said Wong, “Industrial water waste treatment, municipal uses. We’re not really cleaning it to drinking water standards. We don’t really need to. It’s a combination of textiles, ultra-filtration membranes, some very rudimentary filtration as well.” explained Wong.

“The basic idea of a Brita filter is that it filters water in stages from the largest materials down to the smallest and what you’re left with is a pretty clean piece of water you can swim in.” said Wong.

“Our biggest concern is bacteria.” explained Wong “There’s I forget how many numbers of different parameters we’re looking at. There’s bacteria counts, pH, oxygen levels, color… but bacteria is the main one. Obviously the reason being that the coliform count is what the Department of Health and the state looked at as the main measure of cleanliness of any body of water that you’re swimming in.” explained Wong.

“In New York state there’s something known as a ‘Bathing Beach’ which is a man made pool. There’s a coliform count that we try to get under. I believe it’s 35 cfu’s per hundred million for bathing beaches.” said Wong, as he explained the requirements his filtration system needs to meet in order to adhere to state health guidelines.

A Concept in Good Company

Wong’s concept for a floating barge style pool is unique in design but has been executed to some degree before. There are similar style concept floating pools such as the Badeschiff in Berlin, La Piscine Josephine Baker in Paris, and Islands Brygge Harbour Bath in Coppenhagen. It’s the ultrafiltration membrane system Wong plans to use that may be unique for a project of this scope and magnitude.

Studies have been conducted on whether ultrafiltration techniques are a viable means of containing coliform counts in pools with higher than average bather loads. Wong along with his team conducted a trial on a smaller scale prototype to see if they could achieve the desired results in terms of maintaining required water sanitization standards.

This pool’s water source and guestimated bather count make the project a unique challenge in terms of keeping the swimming pool within the mandated requirements. Wong elaborated on how he plans to accomplish the daunting task of using water from the East River and making it safe enough to swim in.

“We’re moving water through a series of geotextiles.” said Wong, “It’s really just smaller and smaller pore sizes that you’re passively passing water through and essentially all that’s doing is capturing particles.”

“The good thing is that bacteria tends to ride on larger particles so it’s actually fairly easy to capture in terms of water filtration. The other aspect is we’re doing this completely without chemicals and one of the reasons is to maintain the natural quality of the water. It’s also for the effect of not swimming in a chemically chlorinated environment.” explained Wong.

“We’re maintaining a flow rate within the pool that mimics any natural body of water. So that the body of water is constantly refreshed.” said Wong.

Typically, ultrafiltration captures fine solids, colloids, bacteria, and viruses through a sieve-like structure which does not allow solids larger than the pore diameter to pass through. The technology of microfiltration and ultrafiltration has been used in numerous industrial applications; a science Wong and his team are confident will work in terms of making the water quality suitable for bathers.

Initially, Wong and his associates were able to raise $41,000 through a Kickstarter campaign to test drive the filtration system they plan to use for the real life Plus Pool. The feasibility tests were conducted in conjunction with the help of fellow researchers from Columbia University.

Arup, an engineering firm, approached the team and offered to give resources. They studied water quality, structure configurations, energy utilization, site potentials, and the filtration system throughout the winter. By May 2011, they had determined that the idea was feasible.

“We’ve been doing a lot of health modeling to show that flow rate combined with our filtration system can keep the cleanliness of the water compared to chemically treated bodies of water.”

The Stigma of The East River

Wong’s plan seems solid given the current technology available. Perhaps it’s the reputation of the East River itself that has a bad rap. For decades in recent memory the East River was known as a polluted waterway that was unsuitable to swim in. However, in recent years, not only has the river become swimmable again, it’s actually the cleanest it’s ever been since the days of the Civil War.

Still, many New Yorkers themselves have trouble getting their mind past the stigma of swimming in the East River. Although it’s been twenty four years since the episode of Seinfeld first aired, folks still laugh at the notion of Kramer finding a new zest for life swimming in what was at the time still a very polluted East River.

There is still a lot of conflicting information pertaining to whether the East River is safe to swim in. In the days of a bygone era, the East River was once a very popular swimming hole for New York City locals.

A glance at the topic on Wikipedia flat out tells readers that the East River may be dangerous to swim in. Not particularly because a large percentage of the city’s sewage runoff winds up in the East River, but because strong tidal currents of up to 5 knots that can make swimming unadvisable for most recreational swimmers.

It’s impossible for many folks to ignore raw sewage and gloss over the ‘yuck’ factor associated with the idea of swimming amidst the city’s flotsam and jetsam. Although the biodiversity has come back incredibly, and you can fish and boat in the river – many still struggle with the notion of eating fish from the East River. In years past odds were good one could fish an old boot out of the river just as frequently as they would a bass.

The CSO (combined sewage overflow) annually accounts for roughly 26 billion gallons of raw sewage and polluted storm water discharging into New York Harbor via 460 combined sewage overflows throughout the city. Experts say that as little as a twentieth of an inch of rain can overflood the city’s antiquated sewage system and cause the CSO’s to kick in and begin dumping sewage into the river.

Those issues and the structural engineering challenges of stabilizing the pool are ones that we addressed with Wong. He and his team envision a safe space in the East River dedicated for recreational swimming. “During non-rainy times the water seems to be ‘cleanish’.” said Wong, however he agreed that during rainy times, the Enterococci levels of the water made it unsuitable for swimming.

Wong’s team has performed 2 in water tests to confirm the notion of whether they could use the filtration technology to keep the water clean. “The first one in 2013, we were just testing all these different textiles.” said Wong, “We built a tank and put it onto a pier in Brooklyn Bridge Park and pumped raw water though it just to see the effects of the filtration. It showed some promise but certainly at that point it wasn’t hitting the mark yet.”

“In 2015, we built ‘Float Lab’ a very small, very DIY version of Plus Pool. It allowed us to swap materials in and out and we sat it in the river and just kind of let it passively filter, and had an additional sort of mechanical system to pump through much more dense filtration material to see what the effects were.” said Wong. “That was the one where we said ‘We can actually clean this, we can actually hit consistent clean water quality levels we need to hit.'”

The East River may not be ready to swim in… yet. Backers like Heineken have sponsored the project and have faith that Wong and his associates can pull it off. During our conversation with Wong, we mentioned some other force factors such as strong tidal currents that could make this a particularly challenging endeavor from an engineering standpoint.

Dong Ping Wong responded to questions regarding his plans to stabilize the structure for the choppy conditions. “One of the site constraints as we’re looking for sites was trying to find pockets along the East River where those currents were a little bit more mitigated. The location we’re looking at now is shielded by a pier structure to the north a little bit of the footing of the Manhattan bridge to the south.” explained Wong.

Wong explained some ways the team plans to stabilize the pool. “There is still a lot of current let alone wave action from boat traffic that passes up and down the river.” said Wong, “There’s 3 things we’re doing. One is just the size of the thing itself. It’s quite large and wide. That alone gives us some stability you find in larger barges. The second thing is how we anchor it. We’re using pre-tension anchors that can ride the currents and tides and weather those hundred year storms we anticipate. The third is and we’re still determining if we need this or not, but adding a layer of wave attenuation to the outside of the pool towards the center.” explained Wong.

Why The Plus Pool?

“We wanted a way so that people who are there for athletic reasons can swim. People who there just to hangout can get a suntan. People who are there swimming for the first time feel comfortable. So basically like 4 pools kind of stuck together in one, that’s the idea,” said Wong “There’s a lap pool, and a sports pool, a lounge pool and a kids pool.” explained Wong as he broke down the various quadrants of the intended design concept.

The second reason for the Plus Pool said Wong “I knew that we needed something that looked different. That looked iconic. That looked striking when you saw it in an image, saw it overhead and for the first time. I think it’s very exciting to do a pool in the East River that filters water but we also knew it needed to look incredible, like something you’ve never seen before. The plus gave us that, the shape gave us that.” continued Wong.

Wong and his associates have been trying to get this project approved for over a decade. The concept has been written about and discussed practically since it’s inception. There has never been a fizzling off point in interest. To be clear, New Yorkers want this pool, and it is evident by the number of independent backers and supporters the project has drawn.

This latest surge on social media and the news comes on the tail end of the project finally getting the green light for approval from the city. It’s a great sign that the project will go ahead as planned, but we asked Wong why this project has taken so long to get off the ground.

“It’s just something that’s never been done before,” said Wong, “Here or elsewhere. You know there’s obviously floating pools. There’s natural pools, but I don’t think there’s ever been one at this scale and one that’s filtering the water the way that we are for public use.”

“Additionally, I think as amazing as New York City is, it’s not the easiest place in the world to do innovative public work because it’s a very large city and legally very complicated.” continued Wong, “There’s definitions for good reason, on what a pool is and what a beach is. There is not a definition for what our thing is, which is sort of a combination of the two.”

Wong and his team definitely hit the nail on the head in that regard. The Plus Pool design concept has been shared all over the world and has been written about everywhere from CNN to Architectural Digest. People everywhere are eagerly anticipating the project.

Dong Ping Wong said that he’s open to a Q&A from the pool industry. If you’d like to learn more about how the actual nuts and bolts work, feel free to ask your questions in the comments.

Want to make an impact and contribute to the project? Buy a Pool Tile and donate to the Plus Pool concept.

Listen to the entire interview with Dong Ping Wong on the Pool Magazine Podcast

Featured Photo Credit, Interior Photos / Design Renderings: Plus Pool