After years of stagnation, construction activity has ramped up on a highly visible plot of land in the heart of Longmont.

The $70 million South Main Station development, located on a 6.8-acre parcel at 150 Main St., is expected to include 253 residential units and 10,000 square feet of retail space.

Construction on the site is "slated to begin immediately," according to a news release from the property's California-based ownership group, Mass Equities Inc. The Ezralow Co., another California real estate development firm, will also be involved in project.

The first residential units are expected to be ready to lease by fall of 2019.

"We're excited that South Main Station will play an important role in meeting the growing demand for new apartments and retail amenities in downtown," Brian Bair, Mass Equities vice president for Colorado development and acquisition, said in a statement.

The mixed-use project — which began with the 2015 demolition of the city's Butterball turkey plant on Main Street — had been dogged by delays in the start of construction due to financing snags and the discovery of possibly contaminated soil.

But heavy construction and excavation equipment was present Wednesday, moving earth around the previously tranquil site.

"We are so proud to have this caliber of development in Longmont," Mayor Brian Bagley said in a statement. "While it seemed to take a long time, we have been working tirelessly behind the scenes to make this vision a reality. Projects like this don't come to fruition overnight, and we are jazzed to be moving into the visible phase of this exciting and highly anticipated development."

A rendering of the future South Main Station. (Courtesy Image / Mass Equities Inc.)

As part of a public-private partnership, the city agreed in 2015 to reimburse $1.25 million in development costs so long as construction timeline benchmarks were reached. This agreement was subsequently amended later that year when soil contamination was discovered. It was amended again in 2016 when the developer struggled to secure financing.

"This is a great example of a public-private partnership, where we could leverage public expenditures to incentivize private investment," Longmont Downtown Development Authority board chair Alex Sammoury said in statement. "This is the kind of transformational project that will beget and catalyze more residential and commercial investment in the downtown area."

South Main is one of the largest developments underway in the city and will add much-needed housing, according to the development authority's 2017 master plan.

"For downtown Longmont, the South Main Station redevelopment offers the biggest opportunity to meet the demand for residential units in quantity," the plan says.

A 2012 study of that area by the city led to the creation of the 1st & Main Station Transit and Revitalization Plan. That plan highlights opportunities to transform the more industrial parcels just of south the downtown core into a pedestrian-friendly neighborhood with homes, shops and other businesses.

The city "has recently completed more than $100 million of public improvements along South Main Street, the Old Town area and St. Vrain River corridor," Bair said in a statement. Those improvements "underscore the city's commitment to the South Main area."

Lucas High: 303-684-5310, lhigh@times-call.com