Colonial Pipeline employees and contractors started Friday afternoon digging out a leaking underground pipeline that spilled hundreds of thousands of gallons of gasoline south of Birmingham and shut down a major cog of the country's fuel distribution network, sparking fears of a gas shortage.

The latest update from Colonial Pipeline states that federal, state and company officials have cleared crews to begin the excavation process, which they had not previously been able to do because of the dangerous conditions created by pooled gasoline and fumes.

Colonial Pipeline also raised its estimate of the size of the spill. The company announced last week that the spill leaked around 6,000 barrels of gasoline, which is 252,000 gallons. They now say the leak is likely between 6,000 and 8,000 barrels, which is 336,000 gallons. A barrel is 42 gallons.

The pipeline was shut down Sept. 9, when the leak was confirmed. Colonial says the flow of the leak is greatly diminished, and temporary plugs have been installed on either side of the leak to minimize the impact.

Representatives of Colonial Pipeline and EPA on-scene coordinator Chuck Berry said the gasoline is contained in a mining retention pond and does not pose a threat to the nearby Cahaba River, which contains numerous threatened and endangered species. Berry said the nearest home is about 2.5 miles from the spill and that the gasoline and vapors do not pose a threat to nearby residents.

The repairs are expected to continue over the weekend, with the leaking pipeline potentially returning to service as early as next week. The company's Line 1, which contains the leaking section, normally transports 1.3 million barrels of gasoline each day to distribution centers throughout the Southeast and the East Coast.

Shutting down the pipeline for seven days represents a potential disruption of 9.1 million barrels or 382 million gallons or gas, though Colonial Pipeline and other companies are finding alternate means to transport the gasoline throughout the country.

The governors of Alabama, Georgia, North Carolina and South Carolina have each declared a state of emergency this week allowing truckers to work longer hours to avoid fuel shortages. Some suppliers have begun shipping gasoline by boat from Houston to New York.

Colonial began using its Line 2, which normally ships diesel fuel and other distillate products, to ship gasoline beginning on Thursday to avoid potential disruption. Line 2 now alternates between shipping gasoline and shipping distillates to try to avoid shortages of either product.

Line 1 is flowing from Houston to west Alabama, but stops short of the leak site. Gasoline from Line 2 is transferred back to Line 1 in Atlanta before moving northeast toward New York.

In addition, the company said it is "exploring alternatives, including the construction of a temporary segment of pipeline around the leak site to allow Line 1 to return to service as rapidly and safely as possible."

The cause and exact location of the leak have not been determined, but more information should be available once the pipeline is excavated.