SAN FRANCISCO — In one of their craziest scouting experiences, the Minnesota Twins have reached a deal with a 24-year-old pitching prospect who has thrown 100 mile per hour fastballs but has never been drafted.

Brandon Poulson was pitching earlier this month for the Healdsburg Prune Packers in a collegiate summer league. His manager was Joey Gomes, the brother of big leaguer Jonny Gomes.

Now, the Twins are about to give him $250,000.

“It’s a great story,” Twins West Coast scouting supervisor Sean Johnson said Tuesday. “This kid came out of nowhere.”

The Twins knew about Poulson from his recent season with Academy of Art University, where he had an 8.38 ERA for the San Francisco school.

Poulson played there after taking a couple of years off to work in his father’s business — “John’s Excavating” — with the thought he’d take it over someday and leave athletics behind for good.

The 6-foot-6 right-hander previously played baseball, but chose football at Santa Rosa Junior College. The Twins think Poulson’s story could make a great movie.

“I played for the Prune Packers summer of ‘13, but missed nearly three-fourths of the games because I was busy working,” said Poulson, who didn’t make his high school baseball team as a freshman.

The Twins are giving him about 10 times more than an undrafted player would typically receive as a bonus. Poulson will begin as a reliever.

Poulson traveled to Minneapolis last week to undergo a physical at Target Field before returning to Northern California, then was cleared Tuesday. He is set to travel Wednesday to the Twins’ rookie club in the Appalachian League in Elizabethton, Tennessee.

Poulson will sign his contract once he reports. He could pitch in a game as soon as this weekend.

Until last fall, Poulson was operating heavy machinery — driving 18-wheelers, front-loaders and backhoes. All the while, he played baseball in a Sunday night men’s league, fittingly called the “Wine Country” league.

“I went to work with my father and didn’t want to gamble with sports anymore,” Poulson said.

He later changed his mind and decided to give baseball one last chance, spending months retooling his delivery with Prune Packers pitching coach Caleb Balbuena.

Poulson’s stats this summer: 31 strikeouts and six hits in 12 1-3 innings, with four saves in 12 appearances.

The Twins consider him among the best athletes they have pursued: A health nut, Poulson weighs 240 pounds and ran a 6.6-second 60-yard dash. He has a 40-inch vertical leap.

The San Francisco Giants wanted to sign Poulson, who also drew interest the Oakland Athletics, Seattle Mariners and Philadelphia Phillies. Those teams didn’t have enough money remaining in their draft pool to match Minnesota.

“He’s a physical specimen. He’s got the best pure arm strength I’ve ever seen,” Twins scout Elliott Strankman said.

Strankman is the only member of the organization who watched Poulson pitch. It took all of 18 throws to convince him.

“We’re cautiously optimistic because we don’t want to put a bunch of pressure on the kid. He could be pretty good. This is uncharted territory for us,” he said.

At Academy of Art’s scout day, only the position players were running 60-yard dashes until Poulson turned up and insisted on sprinting. He hadn’t warmed up and was wearing only socks.

“I had cold legs,” he said. “Maybe I would have run it faster.”

Strankman went to see him pitch for the Prune Packers on July 15. Poulson reached agreement on a contract two days later.

This week, Poulson is headed for the minor leagues.

“I’m excited,” he said. “I know it’s just the first step of what the real goal is to make it in the bigs.”

Poulson said one of his first purchases will be a therapy device to help his father with his diabetes.

Poulson went 0-0 with a high ERA in 14 appearances and 19 1-3 innings for Academy of Art this season. He struck out 24, walked 24 and opponents hit .189 against him.

The Twins, who selected shortstop Nick Gordon with the fifth overall pick in last month’s draft, had the financial flexibility to pull this off.

“It was a group effort. You just don’t see stuff like this every day,” Strankman said. “It’s one of those great days as a scout you hope you have every five years.”