A planned development at the former Twin Cities Army Ammunition Plant site can contain higher density housing — with nearly 2,000 units — under key zoning changes the Arden Hills City Council approved Monday.

After a long discussion that turned testy at times, council members voted 3-2 to approve the changes, which bump up by 500 the maximum number of housing units allowed at the planned development known as Rice Creek Commons — from 1,460 to 1,960.

Housing density at the 427-acre former superfund site, one of the last large undeveloped pieces of land in the metro area, has been a point of conflict between the city and Ramsey County, which jointly govern the site's development, with county officials pushing for as many as 2,500 units.

Council Member Tena Monson called the vote a milestone in the life of the project. "The number of housing units and the number of affordable housing units was the primary sticking point," she said. Twenty percent of units will be affordable at 60% of area median income or less.

Monson and fellow council members Thomas Fabel and Emily Rousseau, all elected in 2022 on a platform of moving the Rice Creek Commons development ahead after years of gridlock, voted in favor of the zoning changes. Mayor David Grant and Council Member Brenda Holden voted against the changes.

The plan for up to 1,960 units was pitched to Arden Hills residents at an open house in November.

The increased density would go into two areas of the Rice Creek Commons site.

Town Center South, near the center of the development, will now allow up to 142 additional units, with part of the area zoned to allow more types of multifamily housing.

Arden Hills will allow as many as 358 additional units on the southwest edge of the development, changing some of the area previously dedicated to office space to residential. This could potentially include single family homes, townhouses and apartment buildings of varying sizes.

Many Arden Hills residents at the meeting Monday spoke in favor of the zoning changes, citing the need for more affordable housing in the region.

"The fact that we are actually talking about development details instead of the 'just say no' period that we went through for so long, that just says we're moving forward, and I'm very excited about that," said Arden Hills resident Chris Hughes. He said he hoped a range of housing options at the site would offer local seniors an affordable place to downsize within their community, as well as offer more housing options for residents with families.

Grant said he felt the density had gone through the roof on the project, and he worries that lot sizes under the plan would be too small. "I think it's going to look like a small version of St. Paul," he said, in contrast to the rest of Arden Hills where lots are larger and residents have more space.

Others have cited concerns over increased congestion on area roads. A Ramsey County traffic study presented to the Joint Development Authority in January found the new plan would result in a 3% reduction in car trips at the site compared to a previous traffic study. Some intersections would see additional stress, the study found, and mitigation, such as signals, could be needed.

Ramsey County Engineer Brad Estochen told development authority members the decrease in projected traffic was due to residential use generating fewer trips than commercial or industrial uses.

Ramsey County commissioners Nicole Frethem, the area's representative, and Victoria Reinhardt, who serve on the Joint Development Authority (JDA), praised the council's approval of the zoning changes at Tuesday's county board meeting.

The county spent tens of millions of dollars to buy Rice Creek Commons in 2013 and clean it up.

The changes will need to be approved by the Ramsey County Board and the Metropolitan Council, which reviews changes to city comprehensive plans.

Monson, who also serves on the JDA, said there's still much to be done as the parties work toward an agreement with developer, Alatus.

"Now we can actually move forward on important details to make sure that we're creating a really good development agreement that would be a win-win-win for the city, the county and the residents," Monson said.