Momentum is gaining on a new major round of redevelopment in Over-the-Rhine that calls for more than 150 apartments, roughly a dozen renovated condos and new office space to be built in the next two years.

The work, valued at more than $100 million, is part of a fourth phase of development under way by the Cincinnati Center City Development Corp. in an area of the Cincinnati neighborhood that's become known as the Gateway Quarter.

Since 2005, the non-profit development firm has helped fuel more than $90 million in new investment that's yielded rehabbed condos and new storefronts - mostly along Vine Street.

Once complete in 2011, this upcoming phase will more than double the size of the Gateway Quarter and the investment that 3CDC has made in to Over-the-Rhine.

"It's really widening the footprint," said Joe Pichler, vice chairman of the board of 3CDC. "This is going to be a significant development for the future of Music Hall, Washington Park and it has a lot of implications for the neighborhood in terms of the potential for more positive spin-offs."

The upcoming work includes the renovation of three, four-story buildings along the 1400 block of Race Street into roughly 32,000 square feet of office space. The buildings, just north of the park, will become the new home of 3CDC next summer when the non-profit corporation moves its 19-employee operation from the Kroger building on Vine Street downtown.

"So many other people have invested in this neighborhood by buying a home or opening a business," said Steve Leeper, president and CEO of 3CDC. "We think it's important for us to show that same commitment to the neighborhood by relocating our offices here."

3CDC plans to lease 7,500 square feet in the building, which will be called Saenger Halle, named after a historic music venue that preceded Music Hall on Elm Street in the late 1800s.

Over-the-Rhine developer Northpointe Group says it also plans to lease 2,000 square feet in the building.

Work on Saenger is expected to begin in December and wrap up by next summer.

Farther north on the 1400 block of Race, a new development partnership between Loveland-based John Hueber Homes and Northpointe Group is preparing to begin a $3.4 million project in December called Westfalen Lofts.

The work includes the renovation of three historic buildings into nine condominiums and one single-family home. A later phase calls for 24 more condos in several buildings located farther north on Race Street.

But the majority of the work staged for this fourth phase is expected to include roughly 152 apartments that will be part of two separate projects.

The move toward rental units - some of which will subsidized for low-income residents - is a step away from the first three phases of the Gateway Quarter, which emphasized home ownership through the development of 157 condominiums. So far, more than 55 percent have been sold.

Officials at 3CDC have said the swing toward developing apartment communities is two-fold. There's a need for a balanced mix of newly renovated rental along with the condos, and planners don't want to be slowed-down by the challenges facing the housing and credit markets.

To that end, work is under way along the west side of the 1400 block of Vine on a $10.5 million development that's expected to include 32-market rate apartments and roughly 14,675 square feet of commercial space. All told, 11 buildings are being renovated, and units will range from studios to one-, two- and three-bedroom apartments. The apartments are expected to be finished by next August.

Just south of that work, planning continues on a $40 million remake of the former Mercer Commons site - a three-acre stretch of roughly 19 vacant buildings and lots between Vine, Walnut, 13th and 14th streets.

Developers say they envision 120 apartments, 30 for-sale units, about 16,000 square feet of commercial space and a 225-space public parking garage on Vine Street.

3CDC has said some of the apartments will be made available to low-income residents, but has yet to disclose how many.

"We're waiting for all of the financing to come together," said Chad Munitz, executive vice president of development for 3CDC. "Once we figure that out, we'll be able to determine what's going to be most feasible."

3CDC has tapped St. Louis-based McCormack, Baron and Salazar to assist on the project, which could be ready by 2011.

Meanwhile, planners say construction is likely to begin in early 2010 on a $40 million facelift for historic Washington Park next to Music Hall between Elm and Race streets. Plans there include a 500-space underground parking garage at the southeast corner of Race and 13th streets. The park will be expanded above the garage about two acres.

Park amenities are likely to include new concession buildings, a civic lawn, a staging area for outdoor concerts and a new playground.