The union and the county had been operating under the terms of the expired agreement until March 18, when the commissioners voted to end collective bargaining and give the union members raises that other employees had already received.
The Maryland General Assembly then approved legislation to force the County Commissioners to reinstate collective bargaining.
Gisin said his union, which represents 87 roads, landfill and park workers, hoped to retain the same contract it had with the county last year.
"We did not seek to improve our position at all. We were only attempting to maintain the status quo," he said.
The county had to reject the proposal for two reasons, County Administrator Rodney Shoop said.
First, its language is contrary to the new state law, Shoop said.
Second, restoring last year's contract would have left union members without the average 3 percent raise granted by the Board of County Commissioners, he said.
Shoop said the County Commissioners felt it was in the best interest of those employees to retain the pay raise.
He said the interim agreement, made during a meeting on July 8, was key because it makes union members subject to the county's new classification and compensation plan.
"We're going to insist on treating employees equal across the board," Shoop said.
The plan, which provides for new wage grades, new job titles in some cases, merit increases based on job performance evaluations and wage adjustments, became effective on July 1.
Shoop said he's optimistic that the county and union will complete negotiations in a short time.
Negotiators are scheduled to meet on Thursday, Gisin said.