A new wave of protests led by thousands of campesinos has erupted against the Tia Maria mining project in the Valley of Tambo in southwestern Peru. The fight against Grupo Mexico's project has been Peru's largest social struggle in 2015 and has claimed nine lives in violent protests. Peasant farmers charge that the mining operations will severely damage the local environment and contaminate their fertile valley. The government is backing Grupo Mexico. Rael Mora reports from Lima.