Some of the most successful charter schools in the Twin Cities have been around for more than a decade, long enough to evolve from humble storefronts or converted office or industrial spaces.

Charter schools with strong track records and enrollment waiting lists are now able to tap financing to build new buildings from the ground up — providing, of course, they can find suitable urban infill locales, which is no easy task.

Tracking down potential building sites that are both big enough and relatively pollution-free can require some pretty creative thinking, which is how Twin Cities Academy — one of the top-rated charter schools in the country — came to settle on a former East Side St. Paul cement plant as the home for its new $12 million facility.

Twin Cities Academy's parade of venues since its 1999 founding mirrors the growth of the charter school phenomenon as a whole. The planned 9.2-acre campus at the longtime Cemstone plant at 1474-1520 E. Minnehaha Av. will be its fourth home.

After using two sites in the W. 7th Street neighborhood, it graduated six years ago to the former Sacred Heart Church Catholic school at 835 E. 5th St. Now the academy, which delivers an academically challenging curriculum to a largely low-income student base, has outgrown that facility as well.

Principal Betsy Lueth says its new digs will provide space for 600 students, in grades 6 to 12, and for the first time give them their own athletic facilities, including soccer and baseball fields. The new building is expected to be ready in August 2016.

"We really wanted to stay on the East Side to continue serving the demographic of students we have now, and this was the only site we found that could do that and also allow us to develop our own playing fields," she said. "We do have Minnesota State High School League sports, but we've been having to lease space for them."

The vision of bucolic green fields and a modern school building at the Cemstone site may seem like a stretch for East Siders familiar with the bleak, dusty plant.

The block bounded by Minnehaha Avenue and Birmingham and Hazelwood streets is the last remnant of what was once a gravel quarry that stretched over much of the neighborhood. While most of it was converted to residential uses long ago, the cement company still uses the remaining site to wash and store its mixer trucks.

While its looks are forbidding, actual contamination at the site was slight. It was cleaned up with the help of a Minnesota Department of Employment and Economic Development grant. Many other possible options were considered before deciding to build new on the cement site, Lueth said.

"Ultimately we found there aren't many existing school buildings or office parks out there that we could retrofit affordably," she said. "Once a charter school has matured like ours has, it's tougher to find a fit."

Colliers International Vice President Eric Rapp, who led the search for Twin Cities Academy's new home, said he's seeing more charter schools opt for either building new facilities or expanding existing buildings, such as when the Twin Cities German Immersion School built an addition onto the former St. Andrew's Catholic School in 2013.

"With the way they're growing, there really aren't many other viable options for them," Rapp said. "We've reached a time in Minnesota when some charter schools have matured and have strong enough enrollments where they can go into the bond market and get some pretty reasonable financing."

Twin Cities Academy's expansion is being underwritten by a tax-exempt bond issue, which is part of a surge in charter school bond financing across the United States, according to the Local Initiative Support Corp. The group reported that $2.5 billion in financing via 150 deals were completed during the 23-month period that ended in April 2014, including a single-year record of $1.3 billion in 2013.

This financing surge has come after a sharp downturn between 2008 and 2010.

Don Jacobson is a freelance writer in St. Paul. He is the former editor of the Minneapolis-St. Paul Real Estate Journal.