In 1974, two engineers came together in the United Kingdom and did what few builders before them had been able to do: come up with a technology that would divert water to allow for in- water construction projects. The cofferdam they created was not only effective; it was temporary, portable, and eco-friendly due to its non-subsurface penetrating design. The novel Portadam® was born, and the construction industry was never the same.

Dating back to Roman times, builders have experimented with dozens of ways to safely divert water from their construction sites, particularly those built in part or fully underwater. For centuries, sandbags were the primary solution. And while they are still employed today, sandbags are no longer the preferred method in commercial construction.

The UK-based engineers tested and perfected the Portadam® in construction sites throughout Great Britain before presenting the North American cofferdam market with their novel solution. The technology, Portadam®, was patented and marketed to the UK construction business in the next few years.


It didn’t take long before news about the new invention traveled across the pond and changed the course of the American construction industry’s history, many thanks to a family of divers in Williamstown, NJ.

In the late 1970s, William Streit operated a family-owned commercial diving operation in South Jersey, outside of Philadelphia. By the age of 20, he had already spent years performing highly specialized construction work underneath various bodies of water around the U.S. If anyone understood the complexities of commercial work under the Atlantic, bays, lakes, and rivers, it was Bill Streit.

One day, he was asked to take on the highly complex job of repairing a leaky pipeline 10 feet deep in a river in Virginia. What he needed to locate and seal the hole was to create a dry environment —a tricky thing to do on a muddy, murky riverbed. To do this, he would need a product to divert the millions of gallons of water surrounding the pipeline. When he came across a trade magazine advertisement for a newly launched water diversion product, he knew that this portable cofferdam product could be just the equipment he needed.

He called the two engineers in the UK, and they flew over with the Portadam®. Streit took the equipment on its “maiden voyage” underneath that Virginia River, and he told its inventors that the Portadam® kept the work site dry as a bone. The pipeline leak was fixed faster than expected, and oil started moving back through in a mere day. Streit’s team safely completed the project while minimizing any environmental damage —from the structure or the leakage.

During those first years, Streit would rent the Portadam® each time he went on one of his marine construction jobs. The equipment proved increasingly valuable to Streit’s projects– as well as to his own business —that he approached the UK inventors about taking a long-term financial stake in the Portadam® company.

What started as a case-by-case rental agreement soon became a partnership, and in 1985, Portadam Inc., the company, was born. While the projects became increasingly complex, Streit found that the Portadam® equipment was up for most challenges that came their way. The team continually made safety and technical improvements to the technology to ensure success for each project as the team expanded their work throughout the U.S., serving key customers around the country.


In the early 2000s, the Streit Family stepped down from the business. The following decade was followed by projects across the US and Canada, as well as internationally, as Portadam Inc. was called in for projects supporting federal and local governments as well as private corporations. The small crew of a handful of employees was now a company comprised of dozens, controlling the water across the USA —including major projects in the Potomac, Mississippi, Schuylkill, and Missouri rivers, to mention a few.

Portadam® became a familiar name in Washington, DC. The U.S. Army Corp of Engineers (USACE), FEMA, National Park Service, and the Bureau of Land Management began calling upon the company to handle complex projects throughout the US.

Over the years, Portadam® cofferdams have been used to implement an extraordinary array of construction projects —all in order to keep the water away and the work site dry. Throughout the years, the very same DNA used to create the original Portadam® in 1974 —from frames to liner

— has remained at the core of every project undertaken by the company.

2000s Continued

The team soon realized: if they could keep water out, perhaps a similar technology could be created to keep water in. It was a problem that had defied builders for centuries: how to keep water where you need it and move it entirely to where you don’t. Thus, Portadam Inc. expanded its service offerings to include Water Storage as well. Revolutionizing the space, Portadam Inc. offered large-scale temporary water storage for unique projects all over the country and overseas.

In the late 2004, the Portadam team began re-configuring the original cofferdam model, creating the company’s first flood-protection solution driven by a request by USACE. Originating from the technologies used to control whether water stays in and stays out, the team developed a system to keep water away. USACE tested the original Portadam system and, in 2005, based on excellent results, purchased five thousand feet to protect critical infrastructure throughout the US.


The flood protection arena was not mature, and while Portadam provided flood protection solutions from time to time, the market only began to show signs of maturation in the 2017/2018 timeframe. With rising waters and changing weather patterns came the increased need to protect assets and people from the dangers of flooding. The increased frequency of devasting floodings became too significant to ignore. As the sea level rises, so too does the need to keep people and property from floods. At that time, Portadam began planning its full-fledged entry into the flood space and thus launched its efforts in 2018, offering best-in-class perimeter barriers. The company officially entered the flood protection industry just as the danger from flooding was clearly heading to its highest in history. To meet the country’s needs, the team developed and engineered the proprietary rapidly deployable barrier system, FloodDefenderTM, based on feedback from USACE and other large commercial and industrial customers.


In 2024, Poseidon Barge, a leading provider of sectional barges and marine construction assets, acquired Portadam, Inc’s assets. Portadam’s expertise and product line added to the Poseidon family brings more complete marine solutions to their customer base.

In all, whether to keep water out or in —or away altogether— Portadam’s three- dimensional business, Water Diversion, Flood Protection, and Water Storage, has become known the world over as a leader in managing the flow of the world’s Number One resource: Water.