Stormwater tanks with HUBER Multi-Rake Bar Screen RakeMax® – Spain's response to the challenges posed by increasingly frequent heavy rainfall events
Spain and the wider Mediterranean region experience intense rainfall repeatedly within very short time periods. This has increased over the last decade. During such events, when several hundred millimetres of rain fall in a short space of time, the ground can no longer absorb the water. This is particularly the case when the heavy rainfall follows a long period of hot weather with no precipitation. Even the smallest streams can quickly turn into frightening rivers that sweep everything away, causing great damage to people and the environment. Recent events in the greater Valencia area in 2024 have shown how quickly heavy rainfall can turn into a disaster.
To avoid such disasters, space must be created for excess rainwater so it does not flow uncontrollably through cities and cause devastation.
Spain’s solution: storm water tanks
Spain's answer to this is storm water tanks. Rainwater is collected in large channels, some of which are up to six metres wide, and fed into an underground storage facility. This reduces the strain on sewage treatment plants and enables valuable rainwater to be stored temporarily or discharged in a controlled manner. However, this rainwater is heavily polluted, carrying all the coarse materials that accumulate on the streets and in the sewers during periods of heavy rainfall.
HUBER Multi-Rake Bar Screen RakeMax® in use
The HUBER Multi-Rake Bar Screen RakeMax® can be used here to effectively remove screenings from the rainwater – fully automatically. This protects the environment and significantly reduces operating costs, as manual cleaning is no longer necessary.
In the Madrid region, great efforts are being made to meet the challenges of today and tomorrow. Canal de Isabel II, a state agency responsible for managing all phases of the integral water cycle in the greater Madrid area, currently supplies and connects more than 6.6 million people. The existing sewer network is approximately 16,000 km long and comprises 155 wastewater treatment plants with a total capacity of 3.2 million m3 per day.
Spain currently has a total of 470 rainwater retention tanks. Of these, 70 are located in the greater Madrid area and are the responsibility of Canal de Isabel II.
Storm water tanks Butarque and Arroyofresno
With the Butarque and Arroyofresno (Pinos) rainwater retention tanks, each with a capacity of up to 400,000 m³ (the largest capacity in the EU), the Spanish HUBER subsidiary HUBER Technology España, S.L.U. has already implemented significant projects with the Multi-Rake Bar Screen RakeMax® for screening storm water. In both plants, the HUBER RakeMax® screens reliably ensure that rainwater is freed of floating matter and waste, allowing the water to be pumped into the sewage treatment plants for further treatment without overloading them.
Storm water tank Abronigales
With the Abronigales project, HUBER Technology España, S.L.U. was able to secure another contract for the treatment of rainwater in storm water tanks. The Abronigales storm water tank has a capacity of around 200,000 m³, which is significantly smaller than Butarque and Arroyofresno. However, the incoming volume flow of 100 m³/s is the largest to date.
The request from the Canal de Isabel II authority reached HUBER Technology España, S.L.U. at the end of 2023 and the project was completed within just six months.
Previous heavy rainfall events had demonstrated that manually cleaning the Abronigales underground rainwater retention basin was costly. Therefore, a quick and effective solution had to be implemented within a very short time
As there were no channels in this underground building to date, we were free to design the channels, and Canal de Isabel II built them based on our proposals and hydraulic calculations.
20 of HUBER Multi-Rake Bar Screen RakeMax®
The decision was made to use 20 HUBER Multi-Rake Bar Screen RakeMax® 5760x1775/40 75°, which then discharge the screenings into a conveyor belt provided by the customer.
Thanks to excellent cooperation between HUBER Technology España, S.L.U., Canal de Isabel II, and HUBER SE's internal departments, the order was placed in April 2024 and production could begin.
As planned, the 20 HUBER RakeMax® screens were delivered in four stages by the end of September 2024.
The aim was to install and commission all 20 machines before the rainy season in autumn 2024.
Unfortunately, the weather was uncooperative, resulting in a delay of installation of a few weeks. Commissioning was successfully completed in December 2024.
The first rainfall events have already shown that the HUBER RakeMax® screens can be relied upon: a reliable partner for screening rainwater – state of the art.
Further projects in the pipeline
And the success story continues: At the end of 2025, another storm water tank in Madrid (La China with a capacity of 130,000 m³) is to be equipped with HUBER RakeMax® screens.
In addition, we are already in discussions with Canal de Isabel II regarding the emergency relief of the Abronigales storm water tank, equipped with HUBER Storm Screen ROTAMAT® RoK2 systems.
Our RakeMax® screen is a success story, and we look forward to many more future storm water projects we will complete together!
