Sanitary Sewer Discharge Compliance
A large retail company was experiencing a history of discharging an oily sand mixture into the sanitary sewer system, which caused solid material to accumulate in the sewer pipes downstream of the facility.
Several sewer back-ups had occurred and the sanitation district requested a meeting to resolve the discharge problem. Sierra attended several meetings with the sanitation district and proposed a sampling program to identify the source of the oily sand mixture and provided an engineered solution to the problem. The team expected that the source was likely from the truck wash facility; however, the sampling program identified additional source areas that included the fueling island floor drain discharge and the discharge from the floor washing machine inside the warehouse.
Sierra designed and obtained construction bids for the installation of three new oil/water separator systems that will remove the oils and solids from the waste stream much more efficiently than the existing systems. The new oil/water separator systems will include a sediment chamber designed to remove settleable solids followed by a parallel plate coalescer designed to more efficiently separate the smaller solid particles and oil material from the waste stream. Additionally, the system includes a polypropylene fiber coalescer designed to remove smaller droplets of oil that pass through the parallel plate coalescer. A major focus of this project was the coordination and communication with the local sanitary sewer district and to maintain a positive attitude toward correcting the problem.