Nature-Based Solutions for Water Management

SMAT’s Raw Water Lagoon was designed on the premise that increasing storage capacity through reservoir construction would ensure water availability and improve quality for the residents of Turin. The unconventional project involved refurbishing inactive gravel quarry sites into reservoirs to access a cleaner and more reliable source of water than that extracted from the River Po. SMAT engaged with their local water regulatory authority, Autorità d’Ambito Torinese, who was responsible for reviewing the initial feasibility study. The project proposal required a two-stage review and approval process from both the local and central regulatory authorities. The strength of SMAT’s business case relied on the principle that the Raw Water Lagoon project would not incur more costs than the existing cost of treatment. Capital expenditures would increase with the construction of the reservoir and pumping station, but in the long-term SMAT could justify a cost reduction using natural infrastructure instead of chemical inputs. The initial review stages were greeted with a high level of interest and requests for additional information from the local government (Autorità d’Ambito Torinese). SMAT recognizes that early engagement with authorities regarding the project design was advantageous as it helped the project pass smoothly through later stages of authorization. 

The project’s construction involved reinforcement of gravel quarry’s slopes and creation of a new pumping facility to deliver the reservoir’s raw water to the existing treatment plant, located 7km away. While it may seem inefficient to transport the water, SMAT calculated that these additional costs were well absorbed when compared to the operational costs of chemicals and filter replacements required to treat dirty water from the River Po. The reservoir’s water is guaranteed to be of higher quality since it undergoes a process of natural filtration while passing through the gravel quarry walls. The utility has additional time to monitor and detect contamination levels in the River before they reach the reservoir supply, rather than having to react immediately to contaminated water pumped directly from the River Po.

Seeing immediate results from the lower chemical inputs and energy usage in their treatment plant, SMAT was convinced to expand the capacity of the Raw Water Lagoon. They have plans to construct a second reservoir by 2024 (IWA/TNC, 2018). The new reservoir will be connected to the existing one, which serves to increase resiliency and avoid the cost of constructing another pumping system. In addition to promoting stakeholder engagement and awareness in this next phase of development, it will be key to strike a balance between the economic and technical prerequisites, notes Armando Quazzo, Development & Marketing Manager at SMAT. For example, it was crucial that SMAT acquired the gravel quarries at the end of their productive lifespans, to guarantee a good price and promote the sustainability of a project that would truly revitalize an idle site. Entering negotiations for these properties at the right moment was an important consideration in the financial analysis of the project.

The slow authorization process for SMAT’s Raw Water Lagoon project is an important consideration when analysing the potential of NBS programs in Italy. Bureaucratic delays are a great hindrance to promising infrastructure projects and can hinder momentum for utilities that have acquired funding and prepared plans. SMAT claims it took a total of 720 days from the date the project was conceptualized to the construction start date. This procedural barrier is an area for evaluation, particularly when considering the potential of infrastructure investments or projects (either NBS, hybrid or grey infrastructure) to address urgent water threats.

Climate change’s role in increasing global temperatures threatens the long-term operation and maintenance of SMAT’s reservoirs. Southern Europe has experienced higher temperatures over the past few years, which can result in a proliferation of algae in the reservoirs. This issue presents a risk to the reservoir’s capacity since it would increase weed growth in the reservoir and subsequent treatment costs for the utility. However, these costs are marginal and in the worst-case scenario of extreme drought or a poisonous substance spill, SMAT would be able to rely on their original abstraction points along river.

The Raw Water Lagoon project transforms an otherwise unproductive gravel construction site into a valuable resource for obtaining high quality raw water. The project improves SMAT’s operational resilience in the face of increasing water scarcity. SMAT calculates that the construction of these two reservoirs guarantees an additional storage capacity of 8 million m3 in raw water supplies (their first reservoir can withstand a volume of 2 million m3 and the second is expected to supply an additional 6 million m3 water) (IWA and TNC, 2018). “With the construction of a second reservoir, we can ensure the availability of water for the City of Turin, with 1 million inhabitants, for at least two months” explains Armando Quazzo.