Gardens to prevent floods, the new project from the Government of Navarra starts working in the UPNA´s Tudela campus

Gardens that can prevent floods. That is how the new sustainable urban drainage system, implemented by the Government of Navarra in the UPNA´s Tudela campus through the public society NILSA, is presented.

The system was installed in three areas of the campus´ car parking and, in appearance, it looks like a garden. The sustainable urban drainage system operates imitating nature´s processes and managing rainwater in its source of generation. In this way, rainfall percolates through surfaces specifically prepared without artificial canalisation to pipes.

Moreover, it allows delaying the entry of runoff water into the municipal sewage networks, enabling its regulation in case of high flow produced by a storm or flood; it reduces pollution washed by water such as plastic bags, wrapping, cigarette butts, hydrocarbons, etc. and optimises wastewater treatment processes.

The regional minister of Territory Cohesion, Bernardo Ciriza, has visited the new installation that has been finished after a 3-year joint work of NILSA and UPNA. During the visit, the General Director of Local Administration and Depopulation, Jesús Mª Rodríguez; the UPNA´s vicerector of Economy, Planification and Strategy, Martín Larraza; the Area Director of the Tudela Campus, Juan Ignacio Latorre; and NILSA manager Fernando Mendoza also took part in the visit.

The implementation of this infrastructure has potential to drain a surface of 3,983 and 2,293 square meters distributed in several differentiated areas. The system installed in the UPNA has measurement devices that will broaden the existing knowledge on the efficacy and efficiency of this kind of infrastructures, as well as on its management.

This action had a budget of 80,000 euros (VAT excluded), funded by NILSA and project LIFE NAdapta.

Resources optimization in wastewater treatment

Up to date, the campus had separated collectors for wastewater and rainwater that converged eventually in a single collector, which means that both rainwater and domestic wastewater mixed and ended up in the wastewater treatment plant (WWTP). This situation, which is the most common one in Navarra municipalities, implies that a big amount of rainwater is treated needlessly as it could infiltrate into the ground instead.

The optimal solution lies on building separated sewer networks that differentiate wastewater to be driven to a WWTP from rainwater that not needs to be treated. Other options is to achieve that rainwater percolates into the ground through these sustainable urban drainage systems.

It must be remembered that the grounds where the UPNA´s Tudela campus is located were crop fields until the 70s of last century, and, since 1945, there is evidence that ditches were built to collect water excess. With this project, the water can filtrate again into the ground.

Hydraulic overload in Tudela

Historically, Tudela suffered problems due to the flow excess that collectors must take, which can be too much in flood situations. NILSA, along wih the Tudela Council and the Water Board, carried out several actions during the last 15 years in order to mitigate this problem. One of the most significant was the construction of a storm tank with a capacity of 4,000 cubic meters and an investment of over 2.5 millions euros.

The UPNA action is oriented towards the improvement of this situation and remarks the suitability of the sustainable urban drainage, as well as its positive impact if used across the whole basin of a collectors network.

This drainage system not only includes the construction of this kind of infrastructures, but also management practices and control strategies designed to drain superficial runoff rainwater in an efficient and sustainable way, to reduce pollution washed from streets and to keep the good quality of underground water bodies.

More pictures and a video available in navarra.es.