The plant just around the corner from Minneapolis’ public works yard can churn out 175 tons of hot asphalt an hour — but very little of it ends up on city streets.

Instead, city trucks regularly drive by the Bituminous Roadways plant two blocks away to pick up asphalt from the suburbs, traveling up to 2,000 miles on their busiest summer days to fetch the material and bring it back.

A manager at Bituminous Roadways raised concerns to a public works supervisor last year about how Minneapolis calculates hauling costs when awarding one of its largest, multimillion-dollar contracts.

The city continued awarding work to Commercial Asphalt, with plants in Maple Grove and Burnsville, over Bituminous Roadways. The Minneapolis company finally stopped trying this spring, leaving Commercial Asphalt the sole bidder — and winner — of a $5.4 million contract in April.

While Commercial Asphalt has always offered the lowest bid, the prices between the companies are roughly the same when accounting for hauling costs, city records show. Some question whether the system makes sense.

The city must “look at the way they’re wasting hard-earned dollars that taxpayers pay in,” said Cam Winton, a former mayoral candidate who has regularly called for more efficiency at City Hall. “We’re putting more wear and tear on the trucks.”

When it buys asphalt for road repairs, Hennepin County takes the distance to asphalt plants into account. The county tends to buy asphalt from Bituminous Roadways for Minneapolis jobs, and contracts with Commercial Asphalt when doing work in the suburbs.

The Minneapolis school system’s grounds and trucking employees also pick up asphalt from Bituminous Roadways for pothole jobs because of its proximity.

In recent years, however, City Hall stopped dividing the work between several players and began choosing a single bidder.

“It’s something we may have missed,” said Council Member Cam Gordon. “The fact that Hennepin County is doing it tells me that … maybe this is something we ought to consider.”

He added: “It sounds like [city public works employees] were coming in with what was going to be the most economically prudent, but maybe not environmentally protective.”

Minneapolis has a policy that encourages city departments to take environmental concerns, including air pollution, into consideration during purchasing decisions. Gordon said he isn’t sure if “this is something we’ve been monitoring as carefully as we can.”

The start of summer is the city’s top time to repair potholes and repave battered roads — work that isn’t possible during Minnesota’s cold, snowy months.

As the weather warms, municipal trucks that plowed snow now haul asphalt heated at more than 300 degrees to work sites all over Minneapolis, arriving in the suburbs as early as 7 a.m. for their first delivery.

The system comes down to making the most of the city’s workers and trucks, according to Paul Ogren, city superintendent of environmental engineering.

“If we were to just use those trucks just for snowplowing, that means those trucks would probably be sitting all summer long,” he said. “And so to get the best [use] of those trucks and the drivers and that sort of thing, keeping them busy doing this type of work to and from sites is good for the entire organization.”

Traveling from the city’s North Side public works facility to Maple Grove is a 24-mile round trip, while driving from its two south Minneapolis public works yards to Burnsville is a 29-mile round trip. That can add up to hundreds of miles of truck driving in a single summer day.

Commercial Asphalt’s plants can produce as much as 700 tons of asphalt an hour, and they come in with the lowest bids because they are much closer to raw materials. They own a gravel pit on their Maple Grove site and can easily truck in other materials from St. Cloud. The sprawling facility has room for them to store large deliveries during the cheaper offseason.

Bituminous Roadways, by contrast, struggles to compete on the price of asphalt alone because it has less storage space and must pay higher rates to truck in materials to a crowded urban area.

“No doubt they’re closer,” Ogren said. “But their mix prices are higher. … We take the low bid unless there’s extenuating circumstances.”

Ogren noted that Bituminous Roadways’ materials still have to be trucked into the city. “It might be more efficient to drive out there [to Maple Grove and Burnsville] where the overall production is more efficient,” he said.

Records reviewed by the Star Tribune show that the difference is nearly negligible when hauling costs are taken into account. Records from 2013 show that when accounting for traveling expenses, it would cost the city up to 0.4 percent more — or $1,898 — for municipal trucks to haul asphalt from the Minneapolis plant instead of those owned by Commercial Asphalt.

The city once operated its own asphalt plant in south Minneapolis, starting in 1968. But in the 1990s, it began exploring alternatives.

The city rejected several proposals by Bituminous Roadways to jointly operate an asphalt plant on the northwest corner of East 28th Street and Hiawatha Avenue.

Citing high renovation expenses and declining production, the city decided it was cheaper to privatize the work and decommissioned its plant in 2004. It began awarding contracts to Bituminous Roadways and Commercial Asphalt.

A city report the following year noted the benefits of keeping its own plant. Those included reduced pollution from vehicles driving longer distances and less fleet maintenance.

Over the last five years, Commercial Asphalt has been one of the largest recipients of city contracts, taking in $25 million even before winning its April agreement.

A Star Tribune examination of asphalt receipts for June 2013 — a busy month for road repairs — found 1,613 trips made for asphalt delivery during that period, occasionally making 100 in a day. The trips spanned at least 38,000 miles.

One of the projects that crews were working on at the time was at 25th and Bloomington. It took 28 trips to Burnsville to deliver the asphalt needed.

The distance from the Minneapolis plant was eight blocks.