Floods have historically affected the Spanish city of Alicante. In recent years, there has also been a marked increase in the frequency and intensity of extreme rainfall as a consequence of climate change.
La Marjal is a public green space built in 2015 to protect the San Juan neighborhood in Alicante from floods caused by torrential rains. The park has 3.6 hectares of floodable surface, with the capacity to collect up to 45,000 m³ of water, and two collectors that collect and funnel the water to two large artificial lakes. The water in the lakes is filtered and purified in a completely natural way by gravel and vegetation.
Besides its role in managing stormwater and protecting the city from floods, the park contributes to people’s wellbeing and to the local biodiversity, serving as a haven for local flora and fauna, particularly birdlife. The lakes of La Marjal, located in the center of the park, fulfill a double function: they are a decorative water feature with a natural water purification system and they also act as stormwater reservoirs, protecting from flooding in a natural way.
La Marjal park is the result of the collaboration between Alicante’s City Council and Aguas de Alicante, the city's water supplier. The technical services of the City Council needed an infrastructure capable of cushioning the torrential rains that frequently flood the streets of this area of the Levant. The flexibility and durability of Firestone’s GeoGard EPDM geomembrane and the technical solutions offered for the different critical areas were decisive in the choice of the geomembrane.
To waterproof the artificial lakes, a geotextile layer was placed on top of the compacted soil, and about 8,000 m² of 1.1 mm thick GeoGard EPDM membrane were placed on top. The filtration zones, responsible for the biological purification of the lake, were given extra protection from root penetration by means of an anti-root barrier. In the perimeter areas, the GeoGard EPDM membrane was covered by gravel, vegetation and decorative rocks. The flexibility of the GeoGard EPDM membrane facilitated the installation process, providing a perfect fit to the organic forms of the lake, including the islands created within the lake.
Since its opening, La Marjal has proven its effectiveness time and time again. In August 2019, the city of Alicante registered very intense rainfall, with more than 100 liters of water per square meter. The La Marjal stormwater reservoir prevented flooding by storing 22,000 m³ of rainwater, a volume equivalent to that of 12 Olympic swimming pools.