Ramsey County officials want an outside mediator to thaw stalled negotiations between the county and the city of Arden Hills about the future development of Rice Creek Commons — the largest shovel-ready tract of land in the county.

County Commissioner Blake Huffman said the county has a responsibility to taxpayers to develop the 427-acre site that was once home to the Twin Cities Army Ammunition Plant (TCAAP).

“Over the last three years we have negotiated in good faith only to be stuck in neutral at what feels like an impasse,” Huffman said at a meeting Monday night.

But Arden Hills officials pushed back on mediation, saying the county first needs to more clearly identify sticking points. After several sharp exchanges, city and county officials agreed to compile a list of obstacles. They’ll meet Feb. 20 to talk about them.

The city and county have been negotiating and sparring over Rice Creek Commons for years.

In 2012, the city and county formed a joint development authority to oversee the redevelopment of the former Army site.

The county bought the land in 2013 and cleaned it up, but the land is part of Arden Hills and any development needs city approval.

In 2016, the city and county seemed to reach an agreement for a mix-used development with 1,460 housing units with 10 percent classified as affordable, but county officials now believe the project should include more homes and make more of them affordable.

In November, the County Administrator Ryan O’Connor sent a terse letter to Arden Hills. The county has already spent more than $40 million on the project.

“Density and affordable housing are core issues in building a sustainable community at Rice Creek Commons,” he said in the letter. “But Arden Hills does not appear open to negotiating these issues further.”

Arden Hills officials appear to view the project as an inconvenience rather than as a benefit, O’Connor said.

City Council members accused the county of presenting them with a “moving target.”

“We’ve been at those numbers for years. I am shocked at the 11th hour, there is a proposal to change it,” said Arden Hills Mayor David Grant.