South of downtown St. Paul, several hundred thousand pounds of limestone, sandstone, soil and other materials slid down the Wabasha Street bluff and covered the roadway on April 28.

Several hundred thousand pounds of overhanging rock still need to be removed before the city can reopen the street.

At least one large section of overhanging weathered limestone must go, and two more next to it are likely goners, as well, city officials said Friday.

Together with the dry shale beneath them and soil above them, the rocks constitute an estimated 400,000 pounds of road hazards that likely need to be drilled, hammered or wedged away. Consultants have recommended line-drilling as opposed to blasting, though nothing has been officially taken off the table.

St. Paul officials hope to have a better sense of when they’ll begin removing that rock, and how, by the third week in June.

“How are you going to remove these blocks and when are you going to do it?” said St. Paul Public Works Director Kathy Lantry, presenting a small gathering of reporters on Friday with initial findings from the Itasca Consulting Group. “We don’t know the answer to each of those questions. We don’t know what we’re going to find once we start peeling back that soil.”

The section of rock that needs to be removed is at least 10 feet thick, 12 to 14 feet wide and 15 to 20 feet deep, said Brent Christensen, a city of St. Paul bridge engineer.

The rock in question sits directly beneath private property — a house and garage — but Lantry said there’s no way that any homeowner can be expected to foot the bill for the work done to date, or the undertaking to come. Related Articles Wabasha Street closed after rock slide onto roadway

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Both St. Paul and Ramsey County declared a “local state of emergency” in the hope that expenses related to the rock slide will be reimbursed, at least in part, by the state and federal government.

ON THE WEB: StPaul.gov/construction and “Wabasha Bluff”

“I can tell you I’ve got two bills on my desk that add up to almost $300,000,” Lantry said.

Immediately following the April 28 rock slide, which drew large limestone slabs some 60 or 70 feet to the city right-of-way, the city cordoned off a 1/4-mile area and hired the St. Paul-based civil contractor Bolander to help secure the site. The Itasca Consulting Group has been working with city bridge engineers to complete a site assessment, based in part on information derived from aerial drones and laser scans.

Lantry said she met this week with the homeowners at the top of the bluff who “have been a little bit nervous and incredibly welcoming. … Our intention is not to assess the property owner. If you assess more than a property is worth, (an) owner would likely just walk away.”

That would leave the city shouldering the expenses anyway for a project that immediately impacts public safety and the public right-of-way.

MECHANICS OF A ROCK SLIDE

Lantry said she was sympathetic to businesses and residents whose daily routines have been altered by the rock slide, which forced the closure of a quarter-mile stretch from the incident location near Plato Boulevard almost to Cesar Chavez Street.

“Thankfully, there were no injuries,” Lantry said.

The weekend after the incident, the St. Paul Festival and Heritage Foundation held the West Side’s annual Cinco de Mayo festival as scheduled after switching staging locations for the popular parade.

Surrounding businesses such as the Wabasha Street Caves and Boca Chica Taco House remain open.

“Coming from the south, (customers) have been having a problem getting to us, but they’re getting to us eventually,” said Donna Bremer, owner of the Wabasha Street Caves, an event space and tour destination. “I don’t think we’ve lost business. But for the tours, people have been arriving late.”

Christensen, the bridge engineer, presented several pages of initial findings on Friday from the Itasca Consulting Group, which are available online by searching for “Wabasha Bluff” under StPaul.gov/construction. Site updates are posted there weekly.

Consultants noted that the bluff — which is topped by soil — consists of a combination of weathered limestone, fresh limestone, shale and more than 50 feet of exposed sandstone, as well as limestone “joints” or vertical channels created by water and natural elements.

Consultants also gathered data on on surface conditions, including groundwater, “which is very germane to erosion,” Christensen said.

Bob Bejblik, who lives at the top of the bluff, said that a smaller rock slide occurred in February 2017, forcing the city to put up guardrails at the the time at the bottom of the bluff along Wabasha Street. In 2011, a massive boulder fell from the cliff, hitting a bakery. The consultants have helped the city initiate a monitoring program that relies on technology to notify officials of any movement along the bluff.

City officials said they could not pinpoint why the rock slide occurred this time, or when the next one will take place.

“This bluff, it was created 10,000 years ago,” said Christensen, noting that the natural freeze and thaw cycle of water as winter becomes spring probably played a factor. “It’s a process of natural weathering. … The bluff is always sloughing off. It’s a river bluff. … I can’t really say why the rock would happen this year versus a different year.”