Salvage work is part of Aqua-Nautik’s Underwater-Work division. Here, the company is flipping back a 400-ton gravel plant excavator from 60’ below the water.

An Aqua-Nautik crew finalized their valve installation on a Miami, Florida, project. CEO and Commercial Master Diver Carsten Thoermer said building underwater has value in areas like Miami, where available land is a premium.

When it comes to construction, there is likely more buildable space out there than you think—underwater, or below the water table, for example.

It’s a message Aqua-Nautik Underwater-Work LLC (Aqua-Nautik) delivers to potential clients early in the planning stages of their projects—when they can get the most benefit from the solutions that underwater construction can offer.

“We provide invisible steps for visible success,” says Carsten Thoermer, Aqua-Nautik Founder, CEO and Commercial Master Diver.

Specialized civil engineering is a large part of Aqua-Nautik’s business in Europe. The company is on a mission to make building below the water table a possibility that is more front of mind for many here in the U.S. The company is working to ensure that more developers know of the value in this kind of construction—especially in areas like Miami, says Thoermer, where finding available land isn’t always easy.

“We can take, for example, a four-story structure and put it underground,” says Bill Mulder, Aqua-Nautik’s Chief Marketing Officer. “It’s often cheaper and faster.”

Below the Surface

Founded in Germany in 2001 and operating in South Florida for about two years now, Aqua-Nautik has made a name for itself in this innovative segment of civil engineering.

A large part of the company’s focus is to spread the word and educate developers on this method of building, says Thoermer. “Installing underwater concrete basements in the water table is not necessarily a well-known technique,” he says, “nor is it always done successfully by other companies.”

The water table is the transition area below the ground level where water saturation begins. An aquifer is the pocket of water underneath. Thoermer explains that his team’s work offers a similar analogy to digging a hole in wet sand at the beach—it eventually starts filling with water from the base of the hole. Putting in a concrete foundation under the hole may seem counterintuitive but mastering the technique has served Aqua-Nautik and its clients well.

“Our Founder, Carsten, has been doing it for years now,” says Mulder. Cofferdams—enclosures built in or around water—are created at the job site to make the company’s specialized type of work feasible.

He adds, “In Florida, many companies try to get the flooding pits dry, which creates pressure on the ground, risking ruptures on the bottom of the pit. We leave the water at its natural level and use special suction pumps to excavate to the proper depth without any risk of ground breaks. Then we remove the sludge and sand and get it ready for the underwater concrete. The sludge is replaced with clear water, so that divers can clearly observe the work underway.”

Calling the installation process a “special recipe,” Mulder says that the pH balance of water increases with the concrete installation, to above-acceptable conditions. “We have a system where we adjust the pH level back to where it’s supposed to be,” he adds.

Aqua-Nautik uses a special tremie-pipe system to pour concrete underwater up to 90 feet below the water table. The bottom section of this system is in fresh concrete, with the water displaced as the concrete rises. Tremies prevent the flowing cement from coming into contact with the water around it and altering the makeup of the cement.

The end result? “The client gets a dry pit where they can build,” says Mulder—where they originally may not have known a new structure could even exist.

High-Flying Teamwork

Aqua-Nautik is most proud of its involvement with a major project now underway at Frankfurt Airport in Frankfurt, Germany. Part of the facility is a former U.S. military air base, Rhein-Main.

Working with 12 American divers and 10 German divers, the tremies on this project will bring 55,000 cubic yards of concrete under the water table in order to build a third terminal at the facility.

Mulder says that the project involves large cofferdams in five areas of the airport property. The work must be completed step by step, with ample time for the concrete to dry in between. Other parts of the new terminal’s construction depend on Aqua-Nautik’s phases of work being completed first.

“The terminal will be one level, with supporting infrastructure such as a monorail located below the water table,” Mulder says. The new terminal will allow the airport to handle over 15 million more passengers each year.

Space-Creating Solutions

Frankfurt Airport’s adoption of this kind of specialized civil engineering, of course, is evidence of it being a viable construction solution for smaller organizations here in Florida as well. It’s an area of building without much competition, Mulder says, because few companies do it.

The key for companies wanting to use underwater cement services from Aqua-Nautik is to involve Thoermer and his team early in the process. The planning phase is vital, he says. Knowing options—early—is to everyone’s best advantage.

“If a general contractor has a plan to build, they already know what they are doing for parking,” Mulder says. But that plan may take up more land and be more expensive than utilizing space available underground, he notes.

But, through conversations early in the process, Aqua-Nautik can deliver its space-creating services, backed by its founder’s 20-plus years of experience. “We need to get to the designers and architects first. They could use this method,” he says, “and know that it’s possible to put parking underneath a building, for example.”

EU Business News has certainly taken notice, awarding Aqua-Nautik its Best Inshore Underwater Services Provider recognition for 2020.

Creating Space, Safety

About 30 of Aqua-Nautik’s 45 employees are commercial divers. Their safety is first and foremost to Thoermer, who was himself a diver in the German military. The company invests in the latest, most reliable diving equipment and underwater tools.

For example, Mulder says that the company has a remotely operated vehicle, so divers don’t have to go into structures such as pipes or culverts underwater without knowing if there is wildlife or other potential hazards inside. Aqua-Nautik offers sonar scanning and imaging to support its divers as well.

Another safety advantage revolves around Aqua-Nautik’s expertise in employing underwater cementing to alleviate flooded roadways. With Florida’s heavy rains, the ability to create underground rainwater retention basins connected with tunnels provides a reliable way to collect and funnel water. Thoermer says it’s a technique used on the Autobahn in Germany, as it helps to keep roads drier and safer. He’d like to see this approach used more often in the Sunshine State as well.

“We are capable of creating rainwater-retention basements with capacity to store thousands of cubic yards of rainwater within the water table,” he adds.

In addition to making space for development below the water’s surface and creating relief on rain-soaked roadways, Aqua-Nautik has mastered water and wastewater treatment work as well.

“For wastewater facilities, many municipalities just assume they need to shut down their plant and drain tanks in order to repair leaks or do other work,” Mulder says. But that’s not the case. “We can do that while fluid or liquid is still there. Some don’t know that’s an option,” he notes, adding that his team uses different diving equipment to service facilities processing clean drinking water.

Project planners and architects can benefit by knowing about the technology Aqua-Nautik has worked to perfect over the past two decades. Mulder says the company’s process for installing concrete underwater offers a range of applications for a wide array of industries.

“We want to put it in the minds of construction companies and other industry professionals because it really is a very big advantage,” Mulder affirms.