How rotomoulding changed safety and debris control forever2 April 2020
IWP&DC spoke with Paul Meeks of Worthington Waterway Barriers and discovered how log booms went from environmentally unfriendly pressure treated lumber that was heavy, costly and difficult to work with to lightweight, durable, highly visible and cost effective designs thanks to rotationally molded plastics
Public safety tailrace barrier at the new 125MW Holtwood Powerhouse in Pennsylvania (US)
Log booms have a long history in the hydropower and dams industry. Historically, log booms were usually made of cut timber or trees, chained together using chain or wire rope – a practise that is still going on today. However, as the industry became ever more concerned with environmental and safety issues, the use of timber and trees started to change. The historical log boom served a singular purpose. Today’s booms are used for multiple purposes and functions. Traditional wooden booms no long fit the need.
One company that has a long history in this particular sector is Worthington Waterway Barriers. CEO Paul Meeks cited an interesting example from around two decades ago where the issues with the historical log boom was made clear. A large federal agency operating dams across the US had purchased a new traditional timber log boom. As with past practices, in order to extend the life of the wooden booms, they would coat and inject them with creosote or other preservatives to slow the process of wood rot. Things went wrong on this particular project. The booms had too much creosote and quickly sank to the bottom of the reservoir after installation.
“This incident forced the owner to look at their practices,” he explained. “They questioned why they were continuing to inject a toxic substance in to the booms that could have detrimental effects on wildlife. They knew they needed booms that were not just environmentally friendly, but less costly to purchase and install.”
Worthington’s TUFFBOOM(R) debris barrier holding massive amounts of post-fire debris following the devastating 2017 fire season in California (US)
TUFFLOAT and TUFFBOOM
Worthington, at that time, was producing a polymer boom for dam owners – originally introduced by its predecessor company, California based RRS industries, who had worked with Sacramento Municipal Utility district to develop a plastic log boom. This product – TUFFLOAT – was the predecessor to the company’s current TUFFBOOM product. Originally designed specifically to replace logs, it has since become the de-facto worldwide standard with utilization in over 63-countries.
Meeks believes the product’s popularity is largely because of its longevity – the plastic polymer log doesn’t corrode. It also offered the project owner the ability to have safety colours on their booms, which meant the boom now has two purposes – safety and debris control. The less dense polymer booms floated higher in the water aiding in visibility. Dam owners quickly saw the benefits for public safety, particularly as the recreational use of reservoirs began to increase considerably.
Debris field in front of the Tillery hydro plant following the 2018 Hurricane Florence in South Carolina (US)
There are of course other reasons for the popularity of these booms. They are lightweight and much easier to install, environmentally friendly, and shipping costs are much lower. Installation costs are typically lower because smaller more standardized equipment can be used. On one occasions Meeks witnessed a jet ski pulling a 300m boom into place!
The boom shells are also non-porous, which can have major benefits as Meeks explained. “The very first sales call I ever made, and this was 25 years ago, was for a flood control dam operated by the US Army Corps of Engineers in Pennsylvania. The project manager there said to me ‘every winter when our reservoirs freeze we are snapping cables and chains that are over1 inch in diameter’. Snapping chain and cable that size means there are tremendous forces on them. In reality, what was happening was the wooden booms they had out there were porous! The ice would freeze into the wood thereby locking the booms into the ice sheet. When the ice sheet moved, it took the boom line with it.
“Worthington’s polymer booms are non-porous so it was impossible for the ice to adhere to the boom itself. The boom line could move independently of the ice sheet. It could rise above the ice sheet, or if the force was high enough it would go underneath it. The bottom line is it wouldn’t snap.”
Benefits of booms
According to Meeks, these booms offer a smarter, more cost effective way of operating. He suggests the three primary benefits of booms are; dam safety; public safety/security and generation efficiency at hydropower dams..
The two most common uses of log booms are to prevent debris from blocking power plant intakes, in order achieve maintain generation efficiency, and to improve dam safety by preventing plugging of spillways or spill gates. Meeks mentioned at incident at the Lake Lynn hydro plant in Pennsylvania two decades ago when a freak summer storm dumped record rainfall over the Lake Lynn watershed. “The result was a dual threat of PMV flows packed with massive amounts of debris. The debris blocked their spillgates to the point where they could no longer pass the design flows. You had a situation where water levels continued to increase because the dam’s ability to pass flow had decreased by nearly 40%. They came very close to overtopping that dam.”
Log booms are essential elements to deflecting debris and aquatic vegetation away from powerplant intakes. Meeks recalls sitting in the plant manager’s office at a newly constructed 3900MW hydro project in Brazil. The manager told him point blank that ‘without these debris booms, the multi-billion dollar powerplant would be inoperable’.
More recently however, Meeks has been consumed by the public safety aspect of booms. People see dams as great recreational sources yet they are often unaware of the dangers. Hydroelectric power plants are industrial power production facilities. Booms, Buoys and Signage are essential elements used by dam owners to safeguard the public from entering into dangerous zones around the dam where the risk of injury or death is elevated.
Xayaburi Dam, Laos
Photograph taken five days after the Worthington debris barrier was installed at the Xayaburi Dam project
Hey...you’re the Tuffboom guy!
People often approach Meeks to say “Hey! I know you! You’re the Tuffboom guy”. When this happens, Meeks smiles, says that is true, and then politely points out that Worthington is more than just the TUFFBOOMproduct. TUFFBOOM is one of many waterway barrier products the company designs and produces. In fact, TUFFBOOM is just a small portion of Worthington’s worldwide business. Today, Worthington is a global powerhouse in the waterway barrier industry with installations in more than 63 countries. To support that broad install base, the company maintains production ncapabilities in the US, France, India, Brazil and Canada.
TUFFBOOM was the world’s first polymer log boom introduced 25 years ago in 1994. All of Worthington’s waterway barrier products incorporate 25-years of lessons learned starting with the first TUFFBOOM installation. The company offers boom units made from rotomolded plastic, HDPE pipe, steel pipe and heavy steel structures where the floats merely serve to float the entire barrier system.
Over the past two years, Worthington has introduced multiple new barrier products, patented safety features and an entirely new method to connect boom units together. “We’ve been able to leverage our nearly 20 years of experience, mostly good but some bad, to design waterway barrier solutions that work. And our focus on modular design principals assures our boom designs are easy to install and for a fraction the cost of other systems.”
“Our customers often see either the familiar orange or yellow float that so distinguishes our barriers, “ Meeks said. “What is not obvious however are the engineered steel frames and screens. Those items are the real barriers. The orange and yellow floats, for the most part, allow these high strength steel debris barriers to float and hold back huge amounts of debris.” Think of it as a high strength steel curtain across a dam. These barriers are designed for long term exposure to tough environmental and operational conditions. The company has developed proprietary design formulas to allow it to accurately determine loads and reactions on boom lines. “In the past we would build a scale model to test some of our barriers. One time we actually contracted with a large Ohio River Barge operator to string a 30m (100ft) boom line in front of the barge train and then drive up and down the river to validate our engineers assumptions. Today however, we operate on a more high tech level. We’ve invested heavily in Flow3D modelling capability and industry leading 3D design software to allow us to model the movement and interaction of debris, ice, hyacinth and people as they encounter our boom lines. We work closely with many of the worlds leading civil engineering firms to assist their project engineering staff to locate, design and implement effective debris, safety and security systems.”
Today you can find a Worthington barrier protecting the nuclear powered submarine fleet of a major NATO country, deflecting floating hyacinth on the Nile river at multiple sites near Cairo, preventing ice blockage at a nuclear power plant in Pennsylvania, and deflecting mass amounts of debris and trash at a just opened hydro plant in Laos. You’ll find Worthington public safety signs warning boaters of the dangers of a dam up ahead. Worthington’s fish guidance systems are allowing for the safe passage of juvenile salmonids as they migrate downstream at dams across the US and Canada. The company’s buoy division provides standard safety and regulatory floats all over. The company just completed a major hyacinth control project in Malawi and are starting on an important debris control project in Pakistan and a security project in the US.