Dewie, a 3-year-old golden retriever, stood watch as repair crews filled a 30-plus-foot deep mine vent Thursday that the pooch plummeted into in January.

The mine vent on state land near Auburn was filled with expanding polyurethane foam, rendering it safe for animals and humans alike.

“This is a great outcome,” said Erica Roper, Dewie’s owner. “We’re happy no one will get hurt in this hole.”

Dewie was out with his owners Marc and Erica Roper as they ran along the Maidu Canal Jan. 21. The dog was chasing a rock down an embankment adjacent to the canal along the American River Canyon when he disappeared.

Dewie, who was not injured, was pulled to safety by Auburn firefighters.

The California Department of Conservation worked with California State Parks to come up with a solution to filling the cavernous hole.

Cy Oggins, manager of the Abandoned Mine Lands Unit of the Department of Conservation Office of Mine Reclamation, said a false bottom was placed in the mine vent and the foam, which expands to 30 times its original size, was added on top followed by a layer of dirt.

“You could literally drive a vehicle over it,” Oggins said. “Now no one will be subjected to the same occurrence as with Dewie.”

There are an estimated 47,000 abandoned mines in California, more than 740 in Placer County and several in the immediate Auburn area that may pose a risk to residents and animals.

The Auburn State Recreation Area is responsible for mines and mine vents within its park boundaries.

State parks personnel placed wire fencing around the opening of the mine vent and placed downed brush and trees to impede a person or dog’s progress prior to the hole being filled with foam.

The foothills are scattered with these old abandoned mine shafts. Most of the shafts are sealed as they are discovered.

Roper said she’s just glad it was her dog that fell down the opening rather than a child.

“There are people all over the canyon,” she said. “A child wouldn’t have survived. I still don’t know how Dewie wasn’t injured.”

The Journal’s Penne Usher can be reached at penneu@goldcountrymedia.com or post a comment.