TRUCKEE — An Emeryville development firm has purchased Union Pacific Railroad’s Truckee railyard, a 30-acre site east of this historic mountain town’s commercial row shopping area.

The firm, Holliday Development, specializes in creative residential and mixed-use developments throughout Northern California and will work with the town in planning commercial/housing development on the site, Truckee Mayor Josh Susman said.

The purchase is “a giant step toward realizing our vision of expanding our downtown …,” Susman said in a news release. “This now-vacant site is critical in achieving the town’s planning philosophy of infill development.”

The railyard, which is encircled by “balloon” tracks where trains turn around, has been vacant since a lumber mill on the site closed in the 1980s and its buildings were removed. Trains will continue using the tracks for now, Tony Lashbrook, the town’s community development director, said in an interview.

“I’m thrilled,” Lashbrook said of the purchase. “This is a huge deal.” Lashbrook said the mill site is fundamental to achieving the goals of the town’s general plan and downtown specific plan.

The latter plan, completed seven years ago, calls for development on the site of 100 multiplefamily residential units, 125,000 square feet of commercial buildings, 30,000 square feet of office space, 250 lodging units and 75,000 square feet of public/institutional space, such as a library, Lashbrook said.

“We’re expecting those numbers to move around somewhat, but that sets the ceiling,” he said, adding that the project will probably be in planning for 1 1/2 years before construction starts.

Recently, an effort by town officials, the Sierra Business Council and California Center for Land Recycling resulted in a $350,000 state grant for the site master plan. Susman said the grant “provided the visibility we needed to push this project forward.”

The project will include “housing opportunities that will meet the needs of Truckee residents,” Susman said, adding that the retail/commercial component “will complement the town’s historic downtown commercial core.”

Holliday Development, which has been known for affordable-housing projects, built residential and mixed-use projects in San Francisco’s South of Market district, Susman said.

The company also was involved in the conversion of San Francisco’s historic Clocktower building. Affordable housing has been identified as a critical need in the Truckee-Tahoe area, where housing costs have soared, and most of the jobs are low paying.