In 2014, Minneapolis demolished the Metrodome and diverted more than 80% of the stadium from landfill, including 80,000 tons of concrete and 4,500 tons of steel

A majority of stadiums send out the same message when they are taken down: rubble, a couple of impressive implosion videos, and a bit fuller landfill. That's not how the Minneapolis Metrodome was torn down, and it's not just for a headline. According to an April 17, 2014, joint announcement from the Minnesota Sports Facilities Authority and Mortenson Construction, the demolition of the Hubert H. Humphrey Metrodome was completed a month early in April 2014, and over 80 percent of the stadium was not sent to a landfill. Of the 80,000 tons of concrete and 4,500 tons of structural steel removed from the wreckage, it was sent for recycling to be used in new construction projects, and precious metals were trundled away from the old seats, as were cast iron and even roof cables. That's a rather unusual retirement plan for a 32-year-old air-supported dome that was home to one Super Bowl and two World Series.

The Metrodome's unglamorous afterlife

People consider games, crowd noise, and perhaps a few viral Vikings collapses when thinking about a stadium's legacy. No one is going to make a film on where the rebar ended up. However, the Metrodome's teardown quietly became one of the more efficient large-scale deconstruction processes in recent American sports history, precisely because the demolition contractor, Frattalone Companies, sorted recycling materials rather than dumping them in a dumpster. All of the material was removed from the stadium in 4,910 truckloads. The steel and concrete didn't go straight from the wrecking site into the new stadium's foundation, though, it was first hauled to off-site recycling yards, like AMG Alliance's facility across the river, where it was sorted, crushed, and processed before some of it was eventually reused, including in construction of the Metrodome's successor, U.S. Bank Stadium.


America's much bigger, much less flattering waste problem

This is where the feel-good part of the story ends. A recycled stadium is a good headline. It's not by itself proof that America has gotten the hang of demolition waste. This U.S. Environmental Protection Agency (EPA) report on construction and demolition materials estimates that more than 600 million tons of construction and demolition debris are produced annually, more than double that of regular household trash (municipal solid waste).

Much of the growth in those numbers is from the destruction of existing buildings, rather than construction of new blocks. The numbers in the press release of Metrodome are good, but they're the exception to the rule. The technology to increase diversion rates exists, but most projects in the U.S. do not achieve an 80 percent diversion rate due to the extra time and resources required for sorting and recycling versus dumping.

The part you may have missed

The only downside to any news about recycled concrete is this footnote: the industry that created the concrete isn't clean. A 2018 peer-reviewed study titled “Global CO2 emissions from cement production, 1928–2017,” published in the Earth System Science Data, compares the amount of fossil fuels being used in the chemical process of cement production with the rest of the cement industry's emissions.

According to the findings, cement production itself is about 4 percent of global fossil fuel emissions and, when energy consumption in firing and transport is included, the total could reach as high as 8 percent of global CO2 emissions. While reusing old concrete as aggregate is a step in reducing new mining and new manufacturing, it does not remove the carbon cost of tearing down the old concrete, as Minneapolis did before pouring a new, 66,000-seat stadium on the same site, U.S. Bank Stadium, which opened in 2016 and has now been hosting games for roughly a decade.

Why should this matter

When it comes to watching sports stadiums get imploded on YouTube for entertainment, there's a more helpful lens: demolition is a resource decision, not one that's simply about a wrecking ball. The teardown of the Metrodome is a good case study for the public authority putting pressure on the contractor to get majority of a building offsite responsibly, and there's little reason it couldn't work the same elsewhere. But it's not the all-in-one solution to the problem. Whether one dome got recycled well shouldn't be the subject of the press release, but it should be the emblem of the way we treat recycling as a once-in-a-blue-moon event rather than a regular occurrence, demanding that it happen everywhere.