Workers trying to plug up an apparent sinkhole at a bridge site in Connecticut ended up with a stinkhole insteadone that will cost an estimated $1 million to repair. Some 18 pilings for an abutment punched through a 72-in.-dia sewer main 24 ft deep, and now temporary bypass lines are being built to divert the 5 million gal of sewage that travels through on a normal day. But if rainfall exceeds 1 in. in 24 hours in the next few days, it could "blow out the streets" of Bridgeport, says John Ryan, collection systems manager for U.S. Filter, the private contractor operating the sewer system for Bridgeport's water authority. Soil that the joint venture of M. DeMatteo Construction Co. and Brunalli Construction Co. dumped into what had appeared to be a sinkhole began showing up at the main plant two months ago, says Ryan. Last week, crews on the $115-million contract "could smell the sewage," says Brian Castler, manager of construction operations for the Connecticut Dept. of Transportation. But the abutment, some 20 ft wide and 40 ft high, has been poured on top of the line, says Ryan. Castler says investigations are ongoing to find out why the joint venture didn't know about the sewer main. The contractor declined comment.