Just before 5 a.m. on Monday, April 18, Capt. Billy Simmons' work cell phone started humming.

That's never good news.

Simmons, who oversees the marine hazard and navigation program for the U.S. Army Corps of Engineers' Norfolk District, holds the Corps' 24/7 hotline. If there's trouble in the district's hundreds of miles of federally regulated waterways, he's among the first to know.

On the other end of the line was the U.S. Coast Guard, which issued Simmons a directive: Figure out how a 750-foot coal collier ran aground in the center of the region's most important shipping channel and put together a plan to clear the waterway for navigation.

Just before 3 o'clock that morning, the MV Petalon — a Greek-flagged bulk carrier loaded down with 84,135 metric tons of Appalachian coal — ground to a sudden halt in the center of Hampton Roads' primary shipping channel, its speed dropping from 11 knots to zero in a matter of seconds, according to a harbor pilot's recounting of the event.

The vessel was drawing more than 47 feet of water and shouldn't have had any problems traversing the channel, which was dredged to a depth of at least 50 feet, according to a survey conducted just weeks before.

"It was completely surprising — a shock. No vessel should ever be able to run aground in that channel," said Lt. Cmdr. Aja Kirksey, who was standing watch for the Coast Guard during the incident.

Matters were made worse when the Petalon, per standard procedure when a ship runs aground, dropped its anchor. Within minutes, an outgoing current swung its stern perpendicular to Thimble Shoal Channel just east of the Chesapeake Bay Bridge-Tunnel, causing it to block about half of the 1,000-foot-wide shipping lane that connects Hampton Roads with the world.

The situation was dire, and the implications were huge.

Dangerous situation

Among the most important of the channel's users is Naval Station Norfolk, the world's largest Navy base, which depends on the water highway to move its largest vessels in and out of port, including aircraft carriers, the centerpieces of the fleet.

Economically, a long-term shutdown of the channel would be crippling. Each day the port is closed to marine traffic, the region loses about $112 million in economic activity, said Capt. Mark Ogle, commanding officer and captain of the port for Coast Guard Sector Hampton Roads.

Keeping the region's series of shipping channels open, dredged and free of obstructions is the job of the Corps' Norfolk District, which employs 554 workers, mostly civilians, and relies solely on Congress for funding.

The Corps' most important sea lane is the 13-nautical-mile-long Thimble Shoal Channel, which stretches from off the coast of the Atlantic, through the Chesapeake Bay and into harbor in Norfolk.

It feeds two channels heading up the Bay — one north to the Port of Baltimore and another west toward the York River. In Hampton Roads, the channel leads to various entrance reaches, including those that serve the Navy, the coal piers in Newport News and Norfolk and several port properties.

The Corps' mission has grown in importance over the last three decades, as ever-larger ships carrying ever-heavier loads flocked to Hampton Roads. And its role figures to become even more crucial as the port attempts to lure giant cargo vessels that are expected to arrive in waves once the Panama Canal expansion is completed in 2014.

Around the world, shipping lines have ordered hundreds of the new, larger vessels that stretch longer than four football fields and hold more than 12,000 twenty-foot container units — more than triple the capacity of most of the ships that call on the port today.

The larger vessels, called "Post Panamax" or "New Panamax" for their ability to squeeze through the enlarged canal once its completed, stretch longer than 1,200 feet and can draw as much as 49 or 50 feet of water.

"One of the critical components to the success of the Port of Virginia is our deep water," said J.J. Keever, a deputy executive director for the Virginia Port Authority. "As container ships continue to get larger and larger, we're in the enviable position among our East Coast competitors to be able to handle those vessels today."