Argentina's government also disclosed a new gas export request.
The key interest rate is currently at a record low of 6.5%.
The project is part of Sabesp's strategy to diversify revenues.
Ramping up investments, the government is accelerating efforts to complete roads, railways, ports and airports by the time it steps down in mid-2021.
The document reportedly points out flaws and possible offenses, and calls for continued investigations.
The Canadian company forecasts that a third phase at the Chilean mine would take annual production to over 600,000t of copper.
The US$69mn project was originally awarded last year but the process was voided by the procurement authority.