A group calling itself Portlanders for a Living Wage says it filed more than 3,000 signatures with city officials Friday to get a referendum on a $15-per-hour minimum wage on the ballot this fall.

The group needed petitions with at least 1,500 valid signatures to move the issue to the ballot.

Groups seeking citywide votes typically file more than the required number of signatures to make sure they meet the minimum in case some signatures are ruled invalid by the City Clerk’s Office.

The ballot question would ask Portland residents if they want to raise the minimum wage for large businesses to $15 an hour by 2017. Businesses with fewer than 500 employees would have until 2019 to raise the minimum wage to that level.

Tom MacMillan, chairman of the Portland Greens, said city officials told the backers of the referendum that they expect to validate signatures within about 10 days.

The referendum campaign was started by the Portland Green Independent Committee, and has since been joined by other local organizations.