MONTPELIER, Vt. (AP) – The city is planning to spend at least $725,000 to stabilize a cliff above Elm Street that poured tons of rocks on the street last month and threatened two apartment buildings.

The city council voted unanimously Wednesday night to enter into negotiations with a company that specializes in cliff stabilization.

Officials said there was little chance of additional rocks slides because freezing temperatures should stabilize the cliff.

No one was hurt in the Dec. 26 slide that sent tons of earth, rocks and trees tumbling into the street.

A state geologist said the slide was likely caused by water that seeped into cracks in the rock.

“As precipitation comes down in the form of snow and rain, water gets down in between the slabs of rock and over time freezing and thawing in spring and wintertime tends to dilate the partings in the rock,” said Transportation Agency Geologist Tom Eliassen. “So the expansion opens up the rock more and repeated cycles of that over the years weakens rock. And then gravity takes hold.”

The block of Elm Street where the slide happened remains closed to traffic and concrete barriers keep people away from the cliff area. Officials say they expect the block to remain closed for two or three months.

Next week, Janod and Associates will begin erecting a fence that will deflect even the largest boulders.

The rubble in the street will remain until the cliff has been stabilized. The construction workers will fix the cliff from the top down, repelling from ropes, removing loose pieces of rock and then installing bolts to hold the cliff together.

“It’s considered a permanent solution. Not interim, not stopgap permanent,” said City Manager Bill Fraser.

The total cost could exceed $1 million.