Non solo rischio di frana a Brienz: il villaggio grigionese protagonista di una spettacolare evacuazione sta anche scivolando verso valle. Per rallentare il fenomeno è stato deciso di costruire una galleria di drenaggio, che diminuisca la pressione dell'acqua nella roccia.
Per costruire l'opera serviranno 40 milioni di franchi: l'assemblea comunale di Albula/Alvra - il comune a cui fa riferimento la località - ha approvato ieri sera (venerdì) il relativo credito con 69 voti favorevoli, 4 astensioni e nessun contrario. Il 90% della somma dovrebbe comunque arrivare da contributi federali e cantonali.
Il problema geologico: il villaggio in questione si trova su una roccia instabile e sta scivolando verso il basso a un ritmo crescente, con un'area di circa tre chilometri quadrati che si sposta di oltre un metro all'anno. La soluzione è far sì che le acque sovrastanti esercitino meno pressione, allungando di 1'650 metri un tunnel esplorativo già esistente, per raggiungere una lunghezza di 2,3 chilometri, tutti costellati da pozzi di drenaggio. L'inizio dei lavori, che dovrebbero durare tre anni e mezzo, è previsto per il marzo 2024.
Il terreno instabile di Brienz
Telegiornale 13.07.2023, 20:00
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