Loch a Bhraoin Hydro Begins Generating Using Pneumatic Mobile Weir Supplied by Dyrhoff Ltd

Loch a Bhraoin hydro began generating clean electricity in October. This 2MW project has the potential to generate enough electricity for 1,700 average UK homes, saving more than 3,800t of CO2 emissions annually. The scheme turned Loch a Bhraoin into a storage reservoir, with an innovative Obermeyer weir to control flood levels. The pneumatic weir, measuring 2.89m high x 18m wide, was supplied by Dyrhoff Ltd and installed in the summer, under supervision from Dyrhoff engineers. Dyrhoff Ltd are the European agents for Obermeyer.


The scheme also benefits from storage and aims to offer balancing services to the grid. It was developed by Inverbroom Hydro Ltd and Hugh Wallace’s Glendevon Energy Co Ltd and received funding from Clydesdale Bank and Thrive.

“It’s fantastic to see Loch a Bhraoin begin generating clean electricity, supporting the UK’s journey to net zero. Glendevon and other contractors have done a brilliant job completing this project on time despite the challenges COVID has presented. We’re really pleased to have been able to provide the mezzanine funding which helped get this project running.” Said Matthew Clayton, Managing Director, Thrive Renewables.

For more information click here.



Dyrhoff Ltd Celebrates 15th Anniversary

Dyrhoff Limited is celebrating fifteen years of successful operation from its base in Folkestone, Kent.

Recognised globally as one of the leaders in the rubber dam and pneumatic gate field, Dyrhoff Ltd has, since 2005, designed, supplied and supervised the installation of 136 rubber dams and spillway gates, across 87 sites in 29 countries across Europe, the Americas, Asia and Africa. In addition, Dyrhoff Ltd is currently working on a further 28 projects for completion in the next three years.

Dyrhoff AS began its association with rubber dams in 1989 as the Scandinavian agent for Sumitomo Electric. At the time the Japanese company was the leading manufacturer and supplier of rubber dams in the world. In 2003, Sumitomo granted Dyrhoff a worldwide licence to sell rubber dams to the Sumitomo design. Dyrhoff Ltd was established in June 2005 to develop this side of the business.

Whilst taking its technical knowhow from the Japanese specialist, Dyrhoff Ltd developed partnerships with suppliers around the world, enabling it to respond to very specific client requirements and remain competitive in this ever-evolving market.

In parallel to its burgeoning rubber dam activities, in 1997 Dyrhoff became the European Agent for Obermeyer Hydro Inc., an American manufacturer of pneumatic spillway gates, supplying the first European Obermeyer spillway gate for the Denkpal Flood Diversion project in Hungary in the same year. This activity was also further developed by Dyrhoff Ltd from 2005 on.

Rubber dams were first thought of as a concept in the 1930s, but it wasn’t until the 1950s when the first rubber dams were constructed by Norman Imbertson of the Los Angeles Department of Water and Power. The idea of using a sealed rubber body attached to a concrete foundation which could be raised or lowered by the addition or removal of air or water proved highly effective, as well as economical. Nowadays rubber dams are a relatively common sight in the US and Asia. Today’s technology enables rubber dams to reach heights of up to 8m, with single spans measuring up to 100 meters in length. As in the 1950s, their relatively low build cost, low environmental impact – they require practicality no maintenance – and long life, make them an attractive solution.


Dyrhoff’s Water Filled Rubber Dam at Azmak, one of three 5m high x 48m wide rubber dams installed at the power plant in Southern Turkey

The Obermeyer gate was developed in the US in the late 1980s, as a bottom hinged, pneumatically inflated spillway gate. Its popularity has grown around the world, particularly in the small hydropower sector, where its ability to control upstream water flow with great precision makes it ideally suited. In addition, Obermeyer pneumatic gates are a popular solution for navigation applications, especially in urban environments where their low visual impact makes them an attractive solution. As with rubber dams, Obermeyer gates are increasingly being selected for flood defence projects.

As one of the world leaders in this highly specialised engineering field, Dyrhoff Ltd now employs a team of ten at its headquarters in Folkestone’s Shearway Business Park, and maintains a sales office in the USA. Among the many projects in the company’s history, supplying five pneumatic spillway gates as part of the UK Environment Agency’s Leeds Flood Alleviation scheme remains one of the highlights.

A number of projects are in development at any given time, ranging from small rubber dams for urban water treatment projects, to multiple span hydroelectric dams on large rivers. Among the projects Dyrhoff Ltd looks forward to completing in the next 36 months are hydropower projects in the USA, Canada, Portugal, Guatemala, Norway, the UK and Italy, irrigation projects in the USA and Africa, and a flagship tidal barrier project in Dubai, part of the 2020 Universal Expo (now to be hosted in 2021-22), as well as the modernisation of several weirs on the Belgian waterways.

Dyrhoff looks forward to the next fifteen years, and continues to develop its range of products to suit a growing number of applications. To view a comprehensive list of completed Dyrhoff projects, please click here.

Leeds moveable weirs help protect city from flooding during recent storms

The Leader of Leeds City Council Councillor Judith Blake has issued a thank you message to the community volunteers and everyone involved in managing the impact of the extreme stormy weather across the city in February.

As a result of the River Aire rising to such high levels, the moveable weir gates at both Knostrop and Crown Point, together with floodgates along Hol Beck as part of the first phase of the Leeds Flood Alleviation Scheme were activated simultaneously for the first time ever. Installed in 2014-16, the moveable weirs at Knostrop and Crown Point were supplied by Dyrhoff Ltd.


The impact of activating the weirs to create more space for the floodwater in the river saw the river level drop by more than 80 centimetres at Knostrop and more than 40 centimetres at Crown Point even as the river continued to rise elsewhere, providing effective resilience to the city centre from the threat of flooding.

Work has already started on the second phase of the Leeds Flood Alleviation Scheme to invest a further £112.1million in flood resilience measures along the Kirkstall corridor and upstream to the upper levels of the River Aire in a full catchment approach, but there remains a funding gap of approximately £25m before the scheme can be fully completed.

Community groups and flood wardens in the city were on alert and working around the clock together with officers from Leeds City Council, the emergency services, partner agencies and stakeholders including the Environment Agency to monitor, respond and help with the clean-up after three successive weekends of strong winds and heavy rainfall led by storms Ciara and Dennis.

Severe rainstorms delivering more than a month’s worth of rain in just 24 hours saw rivers in Leeds reach their highest levels since the Storm Eva floods caused devastation across the city and region at Christmas in 2015. Together with wind speeds of up to 70 miles per hour, issues were reported across the city including localised flooding in and around Otley, along the A660 corridor and in the Allerton Bywater area.

Leader of Leeds City Council Councillor Judith Blake said:

“I’d like to say a big thank you on behalf of the city to everyone involved in dealing with the impact of the recent storms and for the clean-up which followed. Working at all hours over successive weekends in such challenging conditions was tough but once again everyone pulled together and did everything possible to keep our city and communities safe. I’d like to pay a particular tribute to all of the volunteers, community groups and flood wardens who gave up their weekends and more to help, they are amazing people and the city owes them a real debt of gratitude.

“While we did have some localised flooding due to issues related to the severity of the storms, it was especially pleasing to see the flood scheme weir gates in full operation for the first time and making a real difference. As with any such new technology we are learning every time we use them, but they did prove effective and this is why we need the government to help us complete the next phase of the scheme in full as well as supporting us to provide the best level of resilience we can across all the watercourses in the city.”

Read the full press release here.

Boralex announces commissioning of 16-MW Yellow Falls hydroelectric station

Boralex Inc. has announced the commercial commissioning of its 16-MW Yellow Falls hydroelectric station, under the terms of a price-indexed power purchase agreement with the Independent Electricity System Operator (IESO) for a period of 40 years.

The station is located on the Mattagami River about 20 km south of Smooth Rock Falls, Ontario, and features two air-inflated rubber dams designed and supplied by Dyrhoff Ltd. The rubber dams measure 4.1m high x 25m and 45m.

Yellow Falls (small)

“It’s with great pride that we are officially commissioning our very first hydroelectric station in Ontario,” stated Patrick Decostre, vice president and chief operating officer of Boralex. “I would like to congratulate all the teams who worked on this project, which diversifies our assets in this province and strengthens our position as a leader in the renewable energy field in Canada.”

For several years, Boralex has worked closely with the local communities, represented by the Mattagami First Nation and Taykwa Tagamou Nation, as well as with the town of Smooth Rock Falls, to develop a project that respects their concerns and the surrounding environment and also provides local economic spinoffs, according to a press release.

Boralex says almost 100 specialized workers were on site when construction was at its peak. The power station has one permanent employee, who ensures continuous operations and maintenance.

The station comprises two 8-MW turbine-generator units closely connected to a water intake, a concrete dam, water discharge facilities and related infrastructure on the Mattagami River.

The hydro facility is expected to contribute about C$7million (US$5.3 million) to Boralex’s annualized EBITDA(A), and its power production will avoid the emission of nearly 2,540 metric tons of CO₂ per year.

Boralex develops, builds and operates renewable energy power facilities in Canada, France, the United Kingdom and the U.S. The company’s asset base is in four power generation types —wind, hydroelectric, thermal and solar. About 15% of its business includes hydropower.

To access the official press release visit https://www.boralex.com/

Dyrhoff Completes Refurbishment and Upgrade of Ilovac HPP rubber dams in Croatia

Among the projects completed by Dyrhoff this year are two replacement rubber dams on the river Kupa, at the Ilovac hydropower facility in Croatia. Measuring 2.58m high by 33.4m each, the two water-filled structures at the 1.4MW run-of-river facility enable a degree of regulation.

As well as replacing the two rubber membranes, at the request of the plant operator, Dyrhoff designed and implemented a number of control system upgrades to enable independent operation of both spans. This will ensure optimum power generation is maintained all year round at the facility.

Ilovac (web)


Završnica power plant upgrade showcased at Slovenia’s Annual Conference for Electrical Power Engineers

The pneumatic gates installed at Slovenia’s Završnica power plant in 2018 were the subject of a paper presented at this year’s Slovenian hydropower conference, held in Laško from 21-23 March.

Zavrsnica (small)

Located in the north of the country close to the Austrian border, the hydroelectric power plant at Završnica opened in 1914 and throughout its long history has been subject to several upgrades. The old wooden flashboards, an upgrade originally installed in the mid-1970s, had reached the end of their life span and after a period of consultation the owners opted to replace them with four Obermeyer spillway gates, each 1m high x 7.3m wide, with the gates’ new PLC control system interfacing with the existing Moste HPP’s SCADA system. Competitive in price and offering the automated regulation required along with minimal maintenance and clean operation, the gates were commissioned in the second half of 2018 and are the first of their type in the country.

The illustrated conference paper can be downloaded in full here (text in Slovenian).

Leeds Flood Alleviation Scheme moveable weir used for first time to protect city centre as need for further defences reinforced

The Leader of Leeds City Council has reiterated the need for further flood defences across the city after a weekend when the Leeds Flood Alleviation Scheme was successfully put into action for the first time.

With heavy rainfall falling on already-saturated land, the trigger point was reached for the moveable weir at Knostrop to be lowered on Saturday for the first time since it was installed in 2017 as part of the £50million first phase of the Leeds Flood Alleviation Scheme.

WEB Knostrop (c) Knights Architects

Photo credit (c) Knights Architects

By lowering the weir, the on call Leeds Flood Alleviation Scheme incident team from Leeds City Council supported by the Environment Agency were able to control the flow of the River Aire in order to effectively protect city centre properties from the threat of flooding.

As river levels continued to rise, the team considered also activating the second weir at Crown Point, with the trigger level there coming within approximately 70mm of needing to be lowered, before the river level slowly stabilised as conditions improved.

Read the full article here.

Yellow Falls HPP nears completion in Canada

The 16MW run-of-river Yellow Falls project is nearing completion in Ontario, Canada, and contractors Pomerleau have recently released a video overview of the project.

Yellow Falls (small)

Dyrhoff was selected to supply two air inflated rubber dams for the project, measuring 4.1m high x 25m and 45m wide respectively. The rubber dams can be seen at 2’01”. The video can be viewed by clicking on the link below:

Environment Agency Flood Action Campaign 2018: help protect people from flooding

The Environment Agency (EA) runs an annual campaign to encourage people to know what to do to protect themselves and their property in a flood. This year, the campaign is aimed at young people aged 18 to 34, particularly renters and young families.

The EA have drafted some articles to explain the risks of flooding to their target audiences renters and young families. Click on the image below to find out more:

EA Flood Poster 2018(2)