Characterization of antimony mineralized rock masses and of the excavated rock and soil for the construction of road infrastructures
Client: Nuovo Farma S.c.a.r.l.
Location: S.S. 223 “del Paganico”, Municipality of Civitella Paganico (GR) and Monticiano (SI)
The infrastructural work consists in widening the Grosseto – Siena track (SS 223 “of Paganico”) of the SGC Grosseto – Fano (from km 30 + 040 to km 41 + 600) to 4 lanes. It is located in the territory of Civitella Paganico (GR) and Monticiano (SI) municipalities, in one of the richest areas in Tuscany in terms of mineral deposits.
The area is interested by a mineralization, extending for about 20 km in N-S direction, which includes important antimony deposits, extracted in Pietratonda (Fogna’s valley), La Selva and Belagaio (Farma’s valley), Tocchi and Vallerano ( Merse’s valley), and Cetine of Cotorniano (Figure 1). The mining activity in the area lasted from the late ‘800 and early’ 900 (“La Selva” mine, Figure 2).
The mineralizations (antimony oxides and sulfides, sometimes associated, in smaller amounts, with mixed sulphides, barite and cinnabar) make very difficult, or at least uncertain, any survey aimed at determining the distribution of the heavy metals concentrations.
- To evaluate the effectiveness and adequacy of the investigation plans and of the sampling and analysis procedures adopted in the design phase and during construction, to verify the presence of heavy metals in the area surrounding the infrastructural work;
- To propose a mining approach to sampling, taking into account the site peculiarities.
- Overview of the infrastructure work and analysis of the environmental context;
- Critical analysis of the technical – legislative, regulatory and administrative contexts, of the current regulations and the technical standards relating to the environment and wastes;
- Thorough literature survey in order to identify the mineralization characteristics and the mining activities that affected the examined area;
- Analysis of the modifications to the previous land conditions induced by the mining activities and the construction works of the existing road;
- Analysis of the investigation results, performed in the design phase and during the construction works, to verify the presence of heavy metals in the rock masses and soils interested by the road works;
- Critical review of the survey plans, the sampling and analysis procedures adopted in the design phase and during the construction works, verifying their effectiveness and adequacy compared to the typical approaches of mining engineering;
- Proposal for a “mining” approach to the rock masses and soils characterization, which takes into account the site peculiarities.