New details surfaced Friday about Opus Development Co.’s next project, a key link in downtown Minneapolis’ march toward the river.

The project will include two ­towers built in two phases on a site commonly known as the Ritz Block for the hotel that stood on the site until 1990. The Minnetonka-based developer first plans to build a 32-story residential tower with 12,000 square feet of ground-level retail — construction targeted to begin in the third-quarter this year.

It will be one of a handful of new high-rise residential towers in a three-block radius looking to capitalize on the revival of Minneapolis’ urban population, raising the question of whether the market is becoming oversaturated.

“We think the demand is still there,” said Dave Menke, president of Opus Development. “The metrics that we pay attention to will, and have proved to, support that kind of supply. And we think we have a very strong site.”

Located along 3rd and 4th streets S. between two of downtown’s most recognizable arteries, Nicollet Mall and Marquette Avenue, the new tower will stare directly into the­ ­Minneapolis Central Library.

Opus has been planning the development for months but gained momentum with city planners after the hullabaloo surrounding the Nicollet Hotel Block — also an existing surface parking lot next to the library that lost its namesake hotel in the early ’90s. City officials recently announced plans to sell the latter block — which is kitty-corner from the Ritz Block — to Bloomington-based United Properties.

The latest details of Opus’ plan were published on the city of Minneapolis’ website in an environmental assessment work sheet. While not a complete concept design, the documents show some tweaks to the developer’s original vision for the site after the city requested more commercial, ground-level activity.

“We are just always listening to and addressing feedback we are getting from city staff,” Menke said. “The near-term focus has been on the streetscape and really activating the lower portions of the project. For that whole stretch along the mall, we’ve introduced a very generous setback from the property line and incorporated the greening from the Nicollet Mall, and we will have that strong block of green that will continue down to the river.”

A makeover of Nicollet Mall will begin this spring, stretching from Loring Park up to the Nicollet Hotel Block on Washington Avenue. Meanwhile, Opus is building Xcel Energy’s second corporate headquarters tower across S. 4th Street and plans to include a skyway connection between it and the new tower on the Ritz Block. Xcel’s new building will share a city block with M.A. Mortenson’s new 30-story 4Marq apartment tower and the Nic on Fifth apartment building, which Opus recently completed and quickly sold off.

The footprint with Opus’ first phase on Ritz will be more than 60,000 square feet and include a residential tower with 364 units and 430 ­parking stalls.

Phase two is contingent on the market and could either be another 32-story residential complex or a 20-story office building.

City Council Member Jacob Frey, who represents part of downtown and has championed efforts for a green gateway to the river, said he is happy with the changes Opus has made to the streetscape and ground-level activity.

“The status quo is a surface parking lot. If you put a shack up and painted it red, that would be an improvement in tax revenue and eyes on the street, but obviously we can do better than that,” Frey said. “We are trying to raise the bar on the developers at a time when the market is hot.”

The project’s environmental assessment work sheet will be available for public comment until April 1. The zoning and planning committee is scheduled to discuss the staff’s report April 23. The City Council is expected to vote on the proposal May 1.