A clogging recirculating sand filter and effluent breaking out of the pressure distribution field in the parking lot of a Chinese restaurant in Middleton, Mass., forced the owner to shut down the system and call a pumper to handle 1,000 gpd of wastewater.The owner hired Dan Otten-heimer, R.S., of Mill River Consulting in Gloucester, Mass., to find a solution. His investigation revealed that the sand filter’s ruptured rubber liner was allowing 500 gpd of infiltration. He found no record of any regular maintenance other than pumping of the grease trap and septic tank.Testing showed septic tank effluent BOD5 at 1,500
