The new Walhalla High School on highway 11, scheduled for a 2015 opening, will add 2,400 gallons of wastewater a day to be processed by the county’s Coneross Wastewater Treatment Plant in Seneca. The flow is to be metered by the city of Walhalla. Bob Winchester, executive director of the Joint Regional Sewer Authority, announced the projection during last night’s meeting of the JRSA commissioners. And if that amount of flow is acceptable to DHEC, Winchester said it’s OK with him.