The U.S. Army Corps of Engineers has completed all field work related to the feasibility of deepening Charleston Harbor for larger vessels from an expanded Panama Canal, officials said Friday.

The federal agency made the announcement during a news conference this morning at Sunrise Point Park on James Island. The announcement followed the Army Corps’ recently completing a two-week project that retrieved samples of materials from 49 sites as far as 15 miles offshore.

The samples were retrieved from as deep as 62 feet underwater to see what exactly would be dredged from the bottom of the ocean. The materials are being sent to a laboratory in Marietta, Ga. for analysis, officials said.

Project manager Brian Williams said today that the study is ahead of schedule since the agency initially planned to complete the offshore sampling within six weeks.

Williams said the offshore samples were done quicker than planned and therefore cheaper than the $500,000 budgeted for the task.

Williams said that samples indicate the materials to be largely soft materials such as silt, clay and sand. That may not require the need for underwater explosions, but Williams added that details on how the dredge will happen will come after the materials are analyzed.

“It’s a very low possibility,” Williams said while holding a sample of the material. “As you can see it is flaking off in my hands.”

The $13 million feasibility study is one of the first stages in the lengthy process of deepening the harbor so it can accommodate the longer ships expected from an expanded Panama Canal to be completed in 2015.

The State Ports Authority wants to deepen the shipping lane an additional 5 feet from its current 45 feet.

Charleston Harbor can receive big ships that draft 48 feet and carry the equivalent of more than 9,500 20-foot shipping containers, but only when the tide is high enough.

The deepening is scheduled to be completed by 2020, with the total cost of as much as $350 million to be shared by the state and federal governments.

The study will be followed by a preconstruction engineering and design phase, which is the last step before dredges start pulling muck from the bottom of the harbor.

Last summer, the Obama administration included Charleston as part of its “We Can’t Wait” initiative to help speed up dredging projects.

The Army Corps has to finish its review in four years, half the time than initially planned. The draft of the feasibility study is scheduled to be completed by the summer of 2014, and a final version is expected to be submitted in September 2015.

Reach Tyrone Richardson at 843-937-5550 and follow him on Twitter @tyrichardsonPC.