Local officials raised concerns this week over plans by Mirant Corp. to upgrade the Morgantown power plant, as residents near its site on the Potomac River in southern Charles County stepped up their protests.

Mirant, the Atlanta-based global energy firm that owns the Morgantown plant, plans to build an unloading station to receive coal from large barges traveling up the Potomac. The firm also plans to erect a third tower, called a wet scrubber, that is intended to lower the plant's chemical emissions to comply with Maryland's Healthy Air Act of 2006.

About 200 residents of Cobb Neck, the rural area near the plant that includes the planned golf community of Swan Point, met with the five Charles County commissioners, members of the county's state legislative delegation and representatives of several state agencies on Saturday. The Maryland Public Service Commission is considering Mirant's proposals.

Until now, the Charles commissioners have avoided commenting publicly on the Mirant proposals because they did not want to appear biased should they end up voting on the matter.

But in an interview Tuesday, Charles County Commissioners President Wayne Cooper (D-At Large) said he is concerned about the environmental and economic impact of the proposals.

Mirant spokeswoman Felicia Browder said Mirant has awarded a contract to Shaw, Stone & Webster, a Stoughton, Mass.-based environmental engineering and construction firm that is a subsidiary of the Shaw Group, to serve as the primary contractor managing the engineering and construction of the scrubber tower. She would not specify the price of the work but called it "a large contract."

Cooper said he is worried that the Massachusetts firm would reap the economic benefits of building the tower, and he called on Mirant to place a premium on hiring local companies as subcontractors.

"If [Mirant] hires people in here from all over the country and brings them in, then all that money is going to be going out of state," Cooper said. "We have an opportunity now to profit from that money being used in our county and our state, and that's what I'd like to see."

Browder said only six firms in the United States were qualified to bid on the primary contract, and none of those firms was based locally. But Browder said Shaw, Stone & Webster likely would hire local laborers for the construction project, which could take several years and require hundreds of workers.

"Given the fact that the Shaw Group has been awarded this on contract and they need to remain within a certain budget and time frame, it's in the best interest for the program for them to hire local labor where appropriate," Browder said.

Other concerns that have been raised by residents and officials include the impact the wet scrubber would have on the county's water supply.

The scrubber, which is designed to reduce the discharge of chemical pollutants into the air, would require about 1.5 million gallons of water each day to scrub the inside of the tower. That is more than the amount of water used daily by the town of La Plata.

Cooper said this would threaten the county's long-term water supply.

"My main concern is are we cleaning the air and destroying the water" supply, Cooper said.

Residents also are protesting how the coal barges would affect the scenic view along the Potomac River. Currently, the plant receives coal mined in the Appalachian Mountains via rail lines. Under Mirant's plan, the plant would import coal mined overseas, such as in Indonesia or South America, and ship it to the plant on barges.

State Del. Murray D. Levy (D-Charles) said in an interview this week that such concerns are legitimate.

"Everybody has concerns, legitimate concerns. There's some very real issues out there, but there's also a set of rules and laws that are to be followed," Levy said, referring to the state's air quality regulations.