RAINBOW -- Another informational meeting about the controversial Liberty Quarry, proposed for 311 acres slightly north of the San Diego-Riverside county line, is scheduled for Thursday night.

The public meeting starts at 7 p.m. at the Rainbow Grange, 2160 Rainbow Valley Blvd. in Rainbow.

Organizers say the event will feature a panel of people who have extensive knowledge of subjects such as real estate and air quality, and who will answer questions from the public about what effect the quarry could have on those matters.

Since Granite Construction Co. proposed the quarry in 2005, the project has been buffeted by waves of opposition from individuals and groups in Rainbow and Temecula.

Critics of the plan say the quarry would add noise, air pollution and more highway traffic to communities close to the quarry, which would sit at the southern edge of Riverside County, west of Interstate 15 and near Rainbow Valley Boulevard.

Other critics have raised concerns about what the quarry would do to the area's wildlife and natural habitats.

"We're trying to get information out to people who probably don't know about this quarry plan," said Kathleen Hamilton, one of the organizers of Thursday's meeting.

Hamilton, a Temecula resident, is a leader of Save Our Southwest Hills, a grassroots group that opposes the quarry. Thursday's meeting is a joint effort by Save Our Southwest Hills and Rainbow Against the Quarry, another opposition group.

"We want people to speak out against this quarry, but you have to get people informed before they can petition against something," Hamilton added.

Gary Johnson of Granite Construction has said that operations at the Liberty Quarry site would not intrude on the lives of nearby residents.

Plans for the quarry must be approved by Riverside County officials before Granite Construction can move forward with the proposal at the eastern border of the Santa Margarita Ecological Reserve. The reserve has protected sites for research and education on Southern California ecosystems.

A draft of the project's environmental impact report - the legally mandated study of the quarry's potential environmental effects - is expected to be completed in the spring.

The meeting Thursday will be one of several community meetings held in the Rainbow area. The last one, held Dec. 5, included a presentation by Granite representative Johnson, who spoke in front of a crowd of about 200 people.

In his overview of the Liberty site plans, Johnson addressed several issues raised by the opponents, such as the noise at the quarry. He said there would be five rock "blasting events" per week between the hours of 10 a.m. and 4 p.m., but that the blasts would be done in a way to minimize the noise and vibration.

Johnson isn't scheduled to be at Thursday's meeting.

"Thursday's meeting is about getting some basic information out there, and giving people a chance to talk to people knowledgeable in these areas of concern," said Jerri Arganda, a leader of the Rainbow Against the Quarry group.

- Contact staff writer Lorell Fleming at (760) 731-5798 or lfleming@nctimes.com.