A Waynesville rock quarry where a major slide occurred last year was operating without rules governing the stability or safety of its massive walls, which tower hundreds of feet in the air.
There are no state or federal engineering standards that apply to quarries, nor do state or federal agencies oversee the excavation plans. Quarry operators are free to blast and excavate the mountainside, unburdened by slope rules — unlike average developers who are regulated by local ordinances and engineering standards for building on steep slopes.
“We don’t have slope stability analysis on (quarry) high walls as a general rule,” said Judy Wehner, assistant state mining specialist with the Department of Environment and Natural Resources.
There are no rules limiting how steep or tall quarry walls can be. A quarry could go years without a geotechnical expert or engineer even laying eyes on the rock face, as far as state and federal standards are concerned.
If such rules were in place, however, the massive and potentially fatal slide last year could have been prevented — as could future slides — according to state and federal inspectors who visited the Waynesville quarry following the accident.
In March 2009, a massive section of rock broke off the quarry wall and buried a drilling rig 300 feet below. Luckily, the slide happened at 5 p.m., and the workers operating the drill had knocked off for the day just 10 minutes earlier or they would have been killed.
The slab of rock was more than 500 feet long and 200 feet high — weighing an estimated 350,000 tons and rivaling the size of the massive slide that occurred in October 2009 on Interstate 40. Blasting on the quarry wall had taken place five hours earlier.
The slide got the attention of federal mine inspectors with the Mine Safety and Health Administration, which cited the quarry for “moderate” negligence.
“The mine operator failed to have a mining method in place to maintain the stability of the wall, bank, slope where people work or travel in performing their assigned tasks,” the federal citation stated.
Quarry managers balked at the citation, according to federal inspection reports.
“Mine operator thought that the citation was bullshit, and said that MSHA was only there to write citations and not to help the operator,” inspectors wrote in a report summarizing a meeting held with quarry managers following the slide.
The quarry, operated by Harrison Construction, has recently come under fire from the surrounding community for expansion plans. The proposed expansion is a direct result of the slide. A large portion of the mining pit is off-limits until the slide can be stabilized and repaired, and the quarry is eager to resume work in that section.
The towering, sheer-vertical walls where the slide occurred must be recontoured with a more gentle incline and a series of benches or terraced steps. To do so, the quarry says it must shave off the top of the mountain to achieve the proper slope.
Neighbors fighting the expansion are mad that the whole community will suffer due to the quarry’s mistake.
“No doubt they have problems over there, but they brought it on themselves,” said Michael Rogers, who lives in the shadow of the ridge the quarry hopes to level off.
The quarry walls rises more than 800 feet from the floor of the mine at their highest point.
“My question is why didn’t they bench it to start with?” asked Ronnie Deweese, another neighbor opposed to the expansion.
However, there were no regulations requiring the quarry to do so. When excavating a mountainside, benches — a series of flat steps or terraces — are often used to break up the vertical rise. The quarry indeed had benches, but not enough, according to post-accident assessments.
The interval or width of benches it isn’t something the state mandates.
“We don’t like to see anything over 50 feet without a bench, but that is just a rule of thumb. There is no rule. We don’t have any rules,” Wehner said.
Quarries must provide drawings and maps when applying for a permit, denoting the slope of the walls and location of benches. But the schematics show what the pit will look like when the mining is complete — not the incremental steps of blasting and excavating to reach that point over the course of many years.
Residential contractors building on steep slopes in Haywood and Jackson counties must hire a certified engineer to design slope stability plans. The local ordinances also spell out criteria for building on steep slopes.
The state does neither when it comes to quarries. That said, state mining officials may choose to insert engineering requirements into a quarry’s permit.
“If we feel like a slope stability analysis needs to be done, then we ask for it,” Wehner said. “We can condition the permit anyway we feel we need to. It depends.”
Wehner could not say how often the state actually does so, however. There were no engineering mandates pertaining to the quarry walls in the 2008 permit the Waynesville quarry was operating under at the time of the slide.
What went wrong
Drillers at the quarry were interviewed by federal inspectors following the slide, and all of them said the wall had shown no signs of trouble. One of the drillers working below the wall minutes before the collapse stated: “the wall looked very good and saw nothing to indicate that there was a problem.” The drillers’ names were redacted from the accident report when it was released as part of a Freedom of Information Act request.
However, geologists or geotechnical engineers — as opposed to rank-and-file quarry workers — may have been able to detect the disaster before it was too late.
“I think the key is having the right people looking at it that are trained to notice those thing as the quarry develops,” said Rick Wooten, senior geologist with the N.C. Geological Survey. “It makes sense to have someone on hand that knows how to recognize or evaluate those things.”
Blasting and excavations by the quarry had exposed a plane of weakness in the mountain, said Wooten, who investigated the slide shortly after it happened. Often, the planes of weakness are visible simply by looking at the rock face.
“A lot of times you don’t have to see all of it to know it is there,” Wooten said.
In this case, no one knows whether signs of problem were indeed noticeable or not.
Another option is to drill a core sample into the mountainside, revealing hazards the naked eye can’t see.
“You can get a pretty good idea where those planes of weakness are and what to expect,” Wooten said.
The state doesn’t require quarries to take core samples, however. The federal inspector investigating the massive slide at the Waynesville quarry noted the lack of core samples with dismay.
“The operator had not done any core drilling to determine the make up of the strata of the wall,” the federal inspection report states.
Not my job
While the state Department of Environment and Natural Resources has a mining division that signs off on quarry permits, there is little oversight by the agency to ensure the stability of quarry walls.
The N.C. Department of Labor has a mining bureau, but slope stability and engineering don’t come under its purview either. It inspects mines for worker safety — making sure miners wear their hard hats and safety railings are installed around the edge of the mining pit.
The giant quarry walls and rock faces that workers toil below — and whether they are at risk of collapsing — aren’t part of the inspection.
“We are not geologists so to speak,” said William Gerringer, chief of the N.C. Department of Labor’s Mining?Bureau.
The state does have a team of geologists in the N.C. Geological Survey, but they aren’t tasked with inspecting quarries or signing off on mining plans as a matter of course.
On occasion, Dr. Kenneth Taylor, the head of the N.C. Geological Survey, has been asked to walk a proposed quarry site when the state mining agency was short-staffed. And it’s a good thing, since he noticed red flags that his mining counterparts didn’t see.
Taylor uncovered signs of recent and recurring landslide activity at a proposed quarry site in Jackson County that had gone unnoticed by the mining officials. And at a proposed quarry down East, Taylor merely had to glance at the site to recognize subtle depressions in the ground as evidence of sink holes. He stopped the mining official who was with him from going any further given the risk of being swallowed.
“There are areas where my specialty of geological hazards can make us realize, ‘OK, that’s not a smart thing to do there,’” Taylor said.
State officials suggested engineering oversight might fall under the purview of the federal Mine Safety and Health Administration. But the feds pointed the finger back at the state.
“The state regulates the permitting,” said Don Ratliff, the regional supervisor of the MSHA out of Knoxville. “Our agency does not require them to submit a written plan.”
That changes after an accident, however, like the one at the Waynesville quarry.
“Once they have a slide develop, if we come in and find they weren’t maintaining the stability of the wall, they have to tell us how they are going to fix it,” Ratliff said.
The federal agency won’t offer an independent assessment of the plan that got submited, however.
“As far as us critiquing it or telling them how they have to do it, we are not allowed to do that,” Ratliff said. “We are not allowed to tell the mine operator how to conduct business.”
The MSHA inspect quarries, including the Waynesville quarry, twice a year. They check the electrical systems, drilling and blasting equipment, company logs, fire prevention and the like. The Mine Safety Act has a section that specifically refers to the stability of quarry walls.
“Mining methods shall be used that will maintain wall, bank and slope stability in places where persons work or travel in performing their assigned tasks,” the act states. But apparently, neither federal nor state regulators monitor exactly how this is being achieved.
Following the March 2009 slide, state and federal agencies perked up. An investigation of the slide was conducted by Dr. Dai Choi, a geotechnical expert with the federal MSHA based in West Virginia, resulting in a citation.
On the state side, mining officials required a certified geotechnical engineer to develop a plan for fixing the slide.
In his investigation, Choi noticed signs that would have clued a geologist into a potential hazard.
He noted a slip displacement of the mountainside above the quarry wall. Choi could also see joints indicating a plane of weakness lurked behind the rock face. Choi also noticed evidence of smaller slides that occurred around the quarry.
“Smaller slope failures were either not noticed or the company could not tell us when they occurred, even though such failures could lead to a larger slide,” Choi said.
Choi also found the quarry failed to divert rainwater running off the mountain from spilling over the quarry wall into joints in the rock, cracking the rock as it froze and thawed.
“Drainage was not provided and [rain] was allowed to run freely down the slope and over the edge of the highwall,” Choi wrote in his report. “Surface run-off ditches were draining into the joint where the slide occurred.”
Choi said it was a primary contributing factor in the slide.
The quarry’s poor rainwater management had contributed to another slide, albeit much smaller, in 2005, according to state reports.
A large stockpile of unwanted material — primarily the top layer of dirt and debris stripped off the mountainside before reaching granite bedrock — partially collapsed in 2005. The stockpile is essentially a big heap, and prior to 2005 it was not being properly compacted, according to a report by outside engineers called in after the slide. Quarry workers would add to the pile from the top down, dumping loads off a hillside onto the pile below. The pile had grown more than 100 feet high.
The slopes of the giant stockpile did not have adequate drainage for rainwater and were not being properly compacted, triggering a partial collapse of the pile, according to the report of an outside engineer hired to assess the slide.
The engineers said the quarry’s method of dumping loads onto the crest of the pile was “not an acceptable method.” Instead, the base of the pile needed to be made wider. The pile should then grow from the bottom up, using a series of benches to access the growing pile. The pile should be compacted as it grows, according to the report by Foundation Systems Engineering based in Knoxville.
One of the grounds for denying a quarry permit is past performance. The criteria specifically cites landslides, and whether past performance “indicates a substantial possibility” of a slide occurring.
State environmental regulators in Asheville were unaware that the Waynesville quarry had been cited following the 2009 slide, even though they are tasked with making regular inspections to ensure the quarry is complying with its permit.
“There were no violations cited after the March 2009 slide,” Janet Boyer, regional land quality supervisor with the Department of Environment and Natural Resources, said after checking the quarry’s file.
Judy Wehner, assistant mining specialist in Raleigh, said the state last week received its first copy of the citation issued more than a year ago. Wehner said she had known about it, however, even though it was not part of the quarry’s record on file with the state.