Replacing the roof on McMinnville’s Wastewater Treatment Plant on Cope Street has revealed damage that almost doubled the cost, from $27,294 to $53,974. According to Water Department director Anthony Pelham, roof replacement was bid last year at a cost of $27,294 to Porter Roofing.“Once they got inside, we had significant rot and there’s no good way to give a full price,” he said. “I had negotiated material and labor and not-to-exceeds.