St. Paul and the Minnesota United have big plans for the area around the Major League Soccer stadium, including a new park, updated streets and an unusual stormwater management system. But the costs are adding up.

City leaders agreed last year to spend $18.4 million on infrastructure around the stadium. City Council members voted Wednesday to contribute another $4 million for facilities in the 34.5-acre site at the intersection of University and Snelling avenues.

The stadium will be a key part of that site in the Midway neighborhood, where United and RD Management are expected to build a mixed-use development.

“This is a short-term investment for a much bigger long-term gain,” said Council Member Dai Thao, who represents the area. He was one of four council members who approved the additional funds.

Council Members Dan Bostrom, Rebecca Noecker and Jane Prince all opposed putting any new city money into the project, beyond the $18.4 million.

The largest new expense will be an additional $2.3 million for a stormwater system that uses captured rain to irrigate the site. It will be the largest stormwater system of its kind in the state and the first such system in St. Paul, according to city staff. The city eventually will recoup about half the cost by charging private developers to connect to the stormwater system. The other half of the $2.3 million will come from a grant and tax dollars.

The city also agreed to contribute $250,000 for expenses like sidewalks, lighting and trees at the so-called “Great Lawn.” The soccer team will own and maintain the .63-acre park for 52 years and it will be publicly available when there are not team events.

“We were able to expand the public’s access to green space in the parks system while sharing some of those costs,” Parks and Recreation Director Mike Hahm said.

The majority of council members said the park was a good deal for the city, but Bostrom, Noecker and Prince said the city should not help pay for a park that the team controls.

Other new expenses include $750,000 to move a traffic signal and improve street medians and $400,000 for “soft costs” like developing a transportation management plan, Planning and Economic Development Department Director Jonathan Sage-Martinson said.

After these improvements, roughly two-thirds of the streets on the 34.5-acre site will be complete, he said.