Guiding and Supporting Environmental Compensations. A Tool for Identifying, Estimating and Disseminating Best Offset Measures in Italian Environmental Impact Assessment and Strategic Environmental Assessment Processes

Territorial transformations are processes that increasingly require control and analysis with respect to environmental protection issues. In order to mitigate the negative effects of these transformations, environmental mitigations have been implemented. However, when these fail to limit all remaining negative effects, environmental compensations become necessary. In the Italian normative, the concept of environmental compensation was introduced through the integration of European directives on Environmental Impact Assessment (EIA), Strategic Environ-mental Assessment (SEA), and other environmental authorization procedures into national law. Today, the regulatory framework is the Environmental Code (Legislative Decree No. 152/2006), which is transposed by regulations at the regional level. In this context, institutional bodies, such as the Turin Metropolitan Authority (TMA), are configured as competent subjects with environmental expertise capable of negotiating with stakeholders to promote a spatial transformation. To support the decision-making process regarding the most suitable compensation measure for plans and projects, this study aims to develop a tool that can guide the selection of the most appropriate compensation measure according to the characteristics of the spatial context and provide a detailed description of the works to be carried out for its implementation. In the future development of the research, the proposed tool will be enriched with the parametric cost for implementing the compensation measures to assess the economic feasibility of the intervention. The tool described is a portfolio of interventions produced in collaboration with the TMA and strongly related to the objectives of metropolitan urban planning tools. From these goals, a set of specific interventions that include Nature-Based Solutions (NBS), Natural Water Retention Measures (NWRM), and Sustainable Urban Drainage Systems (SUDS) was identified. Each intervention was accompanied by a detailed description, draws and figures, and a parametric estimation, supported by existing price lists and case studies. This tool is designed to be adaptable over time, following what are the rapid developments in the market, and constantly updating the proposed estimations and possible interventions.