State officials want to know what Mount Airy and borough officials plan to do with its waste once a proposed mini-casino opens its doors. The state Department of Environmental Protection wants Big Beaver officials to submit an official sewage facility plan to the state before it will give its blessing to Mount Airy Pittsburgh. The plan would outline the borough’s wastewater and sewage-disposal needs and its proposed treatment solution. The facility would be just off Interstate 376 at the intersection of Shenango Road and Fairlane Boulevard in Big Beaver.