The $3.25-billion effort to build massive new locks on both entrances of the Panama Canal has been delayed by six months beyond the previously announced schedule, said officials with the Panama Canal Authority, the agency that oversees the canal.

The international consortium handling the lock's construction, Grupos Unidos por El Canal, notified the authority—known by its Spanish-language acronym, ACP — of the new altered schedule on April 3.

The delay follows a weeklong work stoppage in January organized by SUNTRACS, one of Panama's largest construction labor unions. The walkout, which only affected workers for Grupo Unidos por el Canal, ended when the consortium agreed to a 13% wage hike.

The locks are the centerpiece of the $5.2-billion third-lane expansion of the canal that, when finished, is projected to double the historic waterway's capacity. The October 2014 completion date had been targeted in part because it marks the canal's centenary anniversary.

The delay is attributed to problems with the concrete mix, which didn't meet the 100-year standard set by the ACP.

According to agency officials, the locks are now on track to be flooded in September, and pre-commissioning tests should go forward in April 2015. The rest of the canal expansion efforts, such as excavation and dredging work, remain on schedule.

The consortium now faces significant fines for the delay that could reach a maximum of $54 million. That amount could increase to $200 million if the completed locks fail the pre-commissioning tests to measure how fast the enclosures can fill with water and the length of time it takes the lock gates to open.

Grupos Unidos por el Canal won the contract to design and construct the locks portion of the project in July 2009 with a bid $36 million below the canal authority's estimate. The consortium is composed of Spain's Sacyr Vallehermoso, Italy's Impregilo SpA, Belgium's Jan De Nul NV, Panama's Constructora Urbana SA (CUSA) and the Netherlands' Heerema Fabrication Group. n By C.J. Schexnayder