A neighbor of ASML, which is undergoing a $100-million expansion at the facility on Danbury Road, is again complaining to town officials about noise, this time noise from normal operations of the microchip lithography machine plant.

The last complaint was in June, over rock crushing noises coming from the construction site where the company is expanding. Now, neighbor Rocky Delfino, who lives right behind the factory, has hired a lawyer, Christopher Russo, of Fairfield, to complain to the Planning and Zoning Commission about a screeching noise that disrupted his family’s barbecue on July 4.

Russo, acting on Delfino’s behalf, spoke to the commission on Sept. 11, the first meeting of the commission since it took its month-long August break.

“It is really loud,” Russo said of the noise, saying people can’t stay outside in the yard when it is occurring.

Russo said he has complained to ASML, but the company has been slow to respond.

ASML was meeting with the Planning and Zoning Commission Sept. 11 in a continued public hearing for the company’s application for a special permit to build a 25,170-foot addition to the south side of the existing facility, at 77 Danbury Road. It will be used as a truck loading dock. The company’s spokesman for the project, civil engineer Jeremy Oskandy, apologized for the slow response but said the company needs to be thorough.

Oskandy identified the noise Russo complained about as being the sound of a worn-out belt on the cooling tower. Workers check the belt three times a week, he said, but if the belt wears out on a holiday or a weekend, they get to it the next day.

“Imagine the screech the belt on your car makes,” Oskandy said, helping people in the audience to understand what kind of noise it is.

Russo asked for tall trees to block the view and provide a sound barrier. Oskandy said the company already has plans to provide such a barrier for the neighbors.

The expansion includes a 700-space parking garage on what was a former parking lot and office and manufacturing areas that would add more than 45,000 square feet of work space across three floors.

The next step in the expansion is that the Planning and Zoning Commission called for a resolution of approval for the parking garage addition, to be voted on at the next meeting.