The sound of construction crews hammering away will echo throughout the north metro for much of the summer as a historic school building project gets underway.

Voters approved the largest school referendum in Minnesota history for Anoka-Hennepin schools last fall. The record $249 million plan will make over or add on to every one of the district's 38 buildings and construct two elementary schools in fast-growing Ramsey and Blaine.

"This is pretty unprecedented," said Chuck Holden, the district's chief operations officer. "There's nothing fluff in this request. There's a real need here."

The 37,000-student school district, the largest in Minnesota, is using the money to expand existing schools by adding classrooms as well as cafeteria and auditorium space to fit a growing enrollment. Some schools virtually unchanged since they were built in the 1950s and 1960s will finally get updated. Libraries, science labs and athletic facilities will be revamped.

And in the wake of heightened school safety concerns nationwide, the district is enhancing security by rebuilding secure front entrances and removing all 62 portable classrooms that have sat outside locked schools like trailers for years.

"Ever since Columbine back in 1999, we've been discussing it as a safety issue," Holden said, referring to the Colorado school shooting. "They were always meant to be a stopgap, but these portable classrooms have become permanent classrooms. They're not ideal."

While some Minnesota school districts are struggling with widening budget deficits, teacher layoffs and declining student enrollment, Anoka-Hennepin is one of the few school systems bucking that trend, adding 60 teachers next fall and building two brand-new elementary schools that will open in fall 2019.

Enrollment dipped slightly the past few years, but it has regained momentum, with more than 600 kids added to the district in 2016. Officials project another 1,200 will enroll by 2021, as the number of building permits soar.

Living in a construction zone

Several metro-area school districts also have asked voters in the past few years to support more than $100 million bond referendums. But Anoka-Hennepin far surpassed the record.

"They have such a strong tax base that they can raise that amount of money," said Greg Abbott of the Minnesota School Boards Association. "But you go outstate and they don't have the tax base and that would never have passed. It's not going to happen in a lot of school districts."

The $249 million price tag was jaw-dropping, but Superintendent David Law said it's because it's the state's largest school district and it serves students from 13 cities, and the money gets spread out for projects at many more schools. Roseville, for instance, passed a $144 million referendum last fall but has 7,500 students — one-fifth the number of students in Anoka-Hennepin.

He pointed out that including improvements to every school may have helped sway voters' support for the bond referendum — the district's first request of its kind since 1999.

"Every community will benefit," Law said, adding that the large scope of the project also means students will be dealing with a construction zone during renovations. "We're going to need to be patient with piles of dirt."

Voters also passed a $226.20 per-pupil operating levy, which will bring in $9.5 million a year for 10 years to cover such operational needs as hiring more custodians and cooks for the extra space, as well as 60 teachers so that class sizes can be reduced. With the two money requests, the owner of a $200,000 home has to pay $11 more a month in taxes to the school district.

"The school district has a good deal of support from its families," said Kate Thunstrom, a parent who helped lead a task force that came up with building recommendations. "It was pretty obvious each school had a need. It's very exciting for our school district to really be making that step."

Libraries were designed around now obsolete encyclopedias, not computers and other devices. Lunchrooms are too small for the increasing number of students. And the security problems of aging portables are a glaring contrast to the permanent buildings, where visitors check in at a front desk.

"It will change a lot of the schools," Thunstrom said of the plan dubbed "Fit for the Future."

Breaking ground

The massive construction project officially kicked off last month with crews breaking ground on the two elementary schools after a late start due to an April blizzard.

The district will start work on classroom and cafeteria additions this month at Andover and Champlin Park high schools. Anoka, Blaine and Coon Rapids high schools will get similar additions. A new entrance will be built at Coon Rapids to separate the auditorium from classrooms to boost security. All 62 portables, which were installed in the mid-1990s and early 2000s, will be removed by 2021.

And a second phase, starting in 2020, will improve athletic and fitness facilities and all schools' science labs and libraries. The district is also seeking input on a plan to shuffle 4,500 students, or 11 percent of students districtwide, to new schools in fall 2019 to relieve overcrowding at some schools and help fill the two new elementary schools.

The construction will take six years to finish, with most of the projects expected to be done within four years. And Holden is orchestrating it all, the biggest project in his 31 years in the district.

"It's very busy," he said. "People are excited about seeing work starting."

Kelly Smith • 612-673-4141

Twitter: @kellystrib