Independent mediator Edwin Benn says teachers deserve a 14.85 percent raise because the mandate for a longer day means they could be working 19.4 percent more time.

Benn’s recommendation falls midway between the initial offers put forth by the Chicago Teachers Union and Chicago Public Schools. The union reportedly requested a 30 percent raise and CPS offered 2 percent in the first year with pay based on performance in the following year.

The fact-finding process is new for CPS and CTU. It was part of a state education law championed by Mayor Rahm Emanuel and his schools team that paved the way for the longer day and made it harder for the union to strike.

Union President Karen Lewis says the fact finder’s proposal is a direct result of that law, commonly known as SB7.

“This is their process and these are their results,” Lewis said.

In remarks made to reporters Monday, Lewis said the law many thought would strip the union of its collective bargaining rights “backfired.”

CPS spokeswoman Becky Carroll said the fact finder’s recommendation would cost the financially strapped district $330 million in the first year alone. Earlier this month, the district released its budget proposal, which drains the system’s reserve fund in order to close a $665 million deficit. The budget proposal only factors in a 2 percent raise for teachers.

Both parties have 15 days to decide whether to accept or reject the fact finder’s proposal.

If either party rejects, the report is made public, bargaining continues and the union is required to wait 30 days before going on strike.

Union leaders say they will make a decision at the House of Delegates meeting on Wednesday.

The Chicago Board of Education also will hold a special session Wednesday to decide whether to accept or reject the report.