For Market Street merchant Barry Newton, Friday’s ceremony kicking off the next phase of the city’s 160,000-gallon-per-minute drainage project was great news, including financially.

“The losses from the rain that inundates the Market area during one of those floods is probably into the hundreds of thousands of dollars,” he said of the storms known to regularly close shops, eateries and other businesses for hours and sometimes days.

“That also includes sales and property damage,” said Newton, who owns an art store and represents other businesses as head of the City Market Preservation Trust.

The ceremony detailed the next step in Charleston’s mega-million-dollar plan to combat flooding citywide.

This latest phase consists of excavating a vertical shaft 20 feet in diameter and 80 feet deep near the intersection of Market and Concord streets adjacent to where the cruise ships embark.

Below ground, the shaft will connect to a more than 4,000-foot-long linear tunnel that, with the aid of pumps, will help push tens of thousands of gallons of rainwater into Charleston Harbor.

Mayor Joe Riley said the drainage should be able to keep up the 160,000-gallon-per-minute pace, even at high tide.

While flooding is a problem all around low-lying parts of Charleston, the Market is particularly troublesome. A creek used to flow in the area before it was covered by landfill.

Because most of the work will be done below ground, the construction is not expected to greatly inconvenience traffic and pedestrians at street level.

Completion is expected by 2014. By 2020, more than $250 million will have been spent combating flooding in the city.

Reach Schuyler Kropf at 937-5551.