AUBURN — Officials at the Maine Department of Transportation are talking to George and Ruth Benjamin about possibly moving their 200-year-old house away from a stretch of Route 136 that caved in last week.

Engineers said Wednesday that they tried shoring up the eroded bank of the Androscoggin River by driving vertical metal sheets into the ground in an effort to save the elderly couple’s house on the other side of the road. But that design failed in dramatic fashion when a 40-foot wall of sand and clay collapsed, taking a tall crane and two workers with it. No one was injured in the accident.

Now, state officials say they’d prefer to build a slope with a more gradual pitch that would rise one foot for every three feet of run. But that would involve taking out a portion of the existing road as well as the Benjamins’ house.

Officials have been discussing their options with the Benjamins, who are in their 90s, and live on the other side of the road from the cave-in. The couple has lived there for the past 40 years following his retirement from the military. They own 108 acres, including vacant land stretching about a mile behind their house.

“It’s a very, very tricky site,” said Jeff Tweedie, the project manager who was involved in the engineering of the riverbank stabilization. Bound on one side by the river and the other side by the house, Tweedie said, “It’s a very, very tight corridor.”

Before designing a new plan to shore up the crumbling wall, state workers are attempting to explain why the sheet-pile plan failed.

Crews were at the site Wednesday collecting soil samples and surveying the area. A combination of factors possibly led to the collapse, Tweedie said.

Vibrations created by the sheet-pile driver and the weight of the crane, coupled with excessive scouring of the riverbank, might all have contributed to the collapse, Tweedie said. And the soils at the base of the metal sheets might not have been resistant enough at the base to support the wall, he said.

“That’s just a theory as to what caused it,” he said.

The new plan will involve putting in a wall aimed at preventing further erosion by river water and ice, and building a more gradual slope to stabilize the upland area, he said.

The shape of the river is eating up that bank “quite quickly,” he said.

Engineers are devising the best way to retrieve the toppled metal sheets and crane from the bottom of the unstable 40-foot wall of sand and clay.

Officials had considered approaching the site from the water by putting a crane on a barge, but that would have involved rebuilding the Durham Boat Launch at a price of roughly $250,000, and dredging the river in the area of the collapse. That option also would have required getting government permits, an often time-consuming process. The price for that option could have run more than $1 million.

The option chosen by officials cost $250,000.

Stabilizing the riverbank with a gradual slope makes the most sense, said Bill Pulver, assistant director of the Bureau of Project Development at MDOT.

“That’s the solution or alternative that’s best equipped to handle the river,” he said Wednesday.

There are inherent risks associated with public works projects, Tweedie said. “It’s unfortunate that this happened, obviously. The department wants everybody to know that we’re working diligently on this right now and hopefully, we’ll get a game plan together as soon as we can to get this fixed.”