A section of Forest Avenue in Portland will be reduced to one lane in each direction this week while crews make an emergency sewer repair, city officials said.The work will begin Monday, July 6, and is expected to be completed within the week, according to the city. Gorham Sand & Gravel, the city's contractor, is handling the repair of a collapsed sewer.Inbound traffic on Forest Avenue will be reduced to one lane between Avalon Road and Allen Avenue.