Marcos Browne, the vice president of YPF's gas and energy division, says the state-controlled company has hired a bank to act as a consultant in negotiations with prospective buyers.
The project is expected to last two years and includes both the tunnel itself and accesses.
The comptroller of the Barranquilla district will perform a special audit into the ownership of local water utility Triple A, which is held by a subsidiary of a Spanish company subject to a corruption probe.
Planned investments to the tune of approximately US$720mn will be a combination of public and private funds.
São Paulo state water utility has called a tender for a civil works contract focused on improving water supply services in Brazil's largest city.