Baseball teams have a head groundskeeper. Golf courses have greenskeepers.

So it’s no surprise that the AMA Supercross circuit, which makes its annual Seattle visit on Saturday (CenturyLink Field, 7 p.m.), has a dirt director.

“That’s his sole job — he purchases our dirt, lines up the storage for it, the trucking for it and the equipment to move it in place,” said Tim Phend, event manager for Monster Energy Supercross, the man who coordinates the rapid construction and dismantling of huge dirt tracks inside 17 stadiums during the annual four-month Supercross tour.

It takes a village, plus a fleet of trucks and earthmovers, to get the work done in roughly a seven-day span. To do so, Phend leans on his dirt director (Dave Allen, based in Illinois), a traveling crew of six dirt specialists, a 14-member operations team and, when the last race is run, around 60 local temp workers who assist with the teardown.

“We’re staged in a corner, waiting for a call from TV that they have cut off the air,” Phend said. “As soon as we have that call, we’re on the floor.”

But where did all that dirt come from? Where does it go?

Phend says the Supercross tour owns the dirt and has storage deals in each city. Seattle’s dirt is stored in Federal Way and, like most cities, is shared with the Monster Jam truck tour.

“It’s been the same dirt for many, many years, way before I came here,” said Phend, in his seventh year. “There’s silty mixture in this stuff. It’s got to have come out of a riverbed. Softer dirt tends to break down.”

“This year we’re pretty lucky because the weather isn’t as bad as many years past. We got three of the lanes built Monday and got them covered with plastic before rain hit it. It’s in better shape than it’s ever been right now.”

Dirt varies by city.

“Houston had very good dirt last week,” Phend said. “It could be that it’s shared with the rodeo, so a bit of straw gets added every year. As that straw decomposes, it adds a little looser material so it’s not so hard-packed.

“The dirt in New Orleans must have come out of the ocean. “We’ve actually had to screen it for seashells.”

Track builds are fast and furious. At CenturyLink, the process began last Saturday morning when the field was covered with polyethylene plastic (Visqueen). A layer of interlocking vinyl panels went on top of that.

Next, two layers of plywood. Then a 5-inch layer of ground asphalt (“road base,” Phend calls it) to keep the track from becoming a bog if rain falls.

Finally about 500 truckloads of dirt, about 1.5 million pounds, are offloaded. Bulldozers and frontloaders (often eight or more) mold it into bumps, humps and tight turns. Then come 750 foam lane barriers, enough to fill three semis, plus a big finish-line video display and several crowd-wowing, fire-spewing towers.

“There’s plenty to do,” Phend said. “It keeps us busy.”

Hometown hero

Poulsbo native Ryan Villopoto has been AMA Supercross world champion the past three years and can clinch a fourth straight crown in Seattle. If he does it, he would be just the second rider (after Jeremy McGrath, 1993-96) to win four straight titles.

Villopoto, 25, won last week at Houston, his fourth 2014 victory. He enters Saturday’s race 45 points ahead of second-place James Stewart with three races left. A margin of 50 or more after Saturday’s main event would give him the 2014 crown.

Yet for all his success he has won in Seattle just once, in 2009, his first 450SX class win. A win Saturday would be his 39th, and he would love to pull it off in the Northwest.

“This is a challenging sport and sometimes things just don’t go the way you plan it,” he said. “Sure, I wish I could have more wins here, but I don’t have any frustrations about it. I come back each year looking to do the best I can, and my hope is to walk away healthy and feeling like I did all I could to win.”