Monday, June 1, 2026
Pamplona, Spain, is known worldwide for its rich history and the famous Running of the Bulls festival, but the city also faces a recurring environmental challenge — flooding. Situated along the Arga River, many low-lying neighborhoods are vulnerable during heavy rain events, creating risks for infrastructure, public health, and residential areas. To address ongoing backflow and stormwater issues, officials in the Navarra region turned to an engineered check valve solution that could withstand severe conditions while blending into the surrounding urban environment.
In 2021, the Commonwealth of the Pamplona Region initiated a large-scale infrastructure improvement effort to reduce flooding in neighborhoods bordering the river. One of the first areas targeted was Rochapea, one of Pamplona’s oldest districts located along the right bank of the Arga River. During heavy storms, floodwaters and sewage routinely overwhelmed the drainage network, resulting in dangerous backflow conditions that affected streets, homes, and public spaces.
Engineering firm Obras Especiales (OBENASA) was selected for the project, while Navarra-based water infrastructure specialist Hidrostank provided guidance on the valve solution. The project team needed a check valve system capable of preventing reverse flow while also meeting several important requirements. The selected valve needed to deliver long service life, resist corrosion, reduce maintenance demands, discourage theft and vandalism, and preserve the aesthetics of the historic neighborhood. Traditional metal flap-gate systems posed concerns because they are visible, susceptible to corrosion, and can become targets for theft due to scrap metal value.
After evaluating available options, Hidrostank worked closely with Proco Products, Inc. to develop a custom-engineered solution utilizing the ProFlex™ Style 790 Low Headloss In-Line Rubber Check Valve. The all-elastomer valve design offered several advantages over conventional metal alternatives, particularly for stormwater and wastewater applications exposed to harsh environmental conditions.
Unlike metal valves, the ProFlex™ Style 790 is not susceptible to rust, corrosion, or erosion. Its rubber construction also eliminates concerns related to scrap metal theft and significantly reduces long-term maintenance requirements. Designed for durability, the valve provides an expected service life of 35 to 50 years, making it an economical and dependable solution for municipalities seeking long-term infrastructure reliability.
Installation efficiency was another major advantage. The lightweight valve design allowed the system to be installed inside the existing pipeline without requiring extensive structural modifications or heavy equipment. By mounting the valve internally rather than at the pipe outlet, the installation remained hidden from public view — an important consideration within the historic Rochapea neighborhood. The concealed installation also protected the valve from external river conditions, including strong currents and wave action that could potentially damage externally mounted systems.
One of the most important technical considerations for the project was minimizing headloss. In stormwater systems, excessive headloss can delay valve opening and contribute to upstream flooding during major rain events. The low-headloss design of the ProFlex™ Style 790 allows the valve to open efficiently under relatively low flow pressure, helping stormwater evacuate more effectively while preventing reverse flow from re-entering the system.
The new 500-millimeter (20-inch) ProFlex™ 790 valves were installed in November 2021 — just ahead of one of the region’s most severe weather events in recent years. In December, Storm Barra brought record rainfall and significant flooding throughout the Navarra region. The Arga River surged dramatically, placing the newly installed valves under intense operating conditions. According to project officials, the valves remained submerged for two consecutive days under approximately 2.5 meters of water. Despite the extreme conditions, the system successfully prevented backflow events throughout the storm.
Following the flooding, inspections revealed that the drainage infrastructure remained in excellent condition. As water levels receded, the ProFlex™ valves effectively evacuated accumulated water and sediment from the pipeline, preparing the system for future storm events without requiring manual intervention. Project representatives also noted that the valves performed more reliably than other valves previously used in similar applications, which had experienced blockage issues caused by debris and sediment buildup.
The successful installation in Pamplona demonstrates the importance of selecting infrastructure solutions specifically engineered for real-world environmental challenges. By combining corrosion resistance, low-headloss performance, vandalism protection, and concealed installation capabilities, the ProFlex™ Style 790 provided the Commonwealth of the Pamplona Region with a durable and cost-effective answer to persistent stormwater backflow concerns.
Today, the Rochapea neighborhood benefits from improved flood protection and increased confidence in its drainage infrastructure — proving that with the right engineering solution, even severe storm conditions can be managed effectively.
