The city of Portland and a local brewer have agreed to bring in a third party to settle a dispute over an estimated $1.5 million in sewer bills the brewery says were never received. City spokeswoman Nicole Clegg tells The Portland Press Herald an independent arbitrator is expected to hear arguments from the city and Shipyard Brewing Co. and render a binding decision, likely by the end of March. Fred Forsley, president and co-owner of Shipyard, refused comment. The city is seeking back payments for a 6-inch water line installed in 1996, for which the brewery was never billed. The brewery was only making payments on about 9 percent of its water usage. The sewer billing error was discovered in 2011.