The Presentation by Southwest Research and Information Center (SRIC) and Concerned Citizens for Nuclear Safety (CCNS):


Mr. Parker received a M.S. in Geology, Michigan Tech, 1960; a B.S. in Geological Engineering and a B.S. in Mining Engineering, Michigan Tech, 1958. Mr. Parker is a Registered Professional Geologist.

Mr. Parker has over 50 years of experience in problems of mine stability in England, Canada, and the United States. Since 1971, Mr. Parker has been self-employed as a mining and geological consultant, specializing in practical rock mechanics, at Jack Parker and Associates, Inc. His clients include about 100 mining companies. Mr. Parker has worked in several hundred mines. He is frequently called to help solve an unexpected problem, like a roof-fall.

Mr. Parker was part of the 1991 panel of experts set up by the DOE to give outside opinions concerning the stability of Panel 1 after the roof-fall in the Site and Preliminary Design Validation (SPDV) Room 1. When Mr. Parker last visited the WIPP underground, in December of 1998, he observed that the rooms in Panel 1 had deteriorated-- especially the roofs. The roofs were broken and supported by roof bolts, which were themselves breaking regularly and requiring continual replacement. Mr. Parker concluded from his observations that the roofs were not stable and that freshly excavated (by nature more stable) rooms should be used for waste emplacement.

Mr. Parker defined the following terms:

Stable: standing without change, neither improving nor getting worse.

Creep: gradual deformation of material under constant stress. The material continually moves plastically. Vertical pressure induces sideways pressure. The salt is behaving like a fluid and flows towards zones of lowest pressure.

Fracture: squeezed salt extrudes sideways. This term is usually applied to more brittle material, but rock salt will do the same thing where it is not confined.

Failure: when roof beams eventually break. A failed roof could be supported artificially, but if not supported it will fall. In Panel 1 there is already roof failure. The supports mask the failure, but one can see shear along the ribs, cracks, and joints in the ceilings. Broken roof bolts and sag in the roof are also visible.

Two convergence graphs were described. [Convergence occurs when two or more objects approach the same point from different directions.] Convergence graphs are used as a tool to predict roof-falls. Figure 8 compares roof-to-floor convergence for SPDV-1 and SPDV-2. [Both rooms eventually had roof falls.] Figure 9 shows SPDV -1 rates per year of convergence. Figure 8 demonstrates that different rooms have different convergence rates. This is not unusual in evaporite mines. [Evaporite is the sedimentary deposit created by the evaporation of seawater.] Failure would not occur at the same time in 2 rooms unless there was a chain reaction. Figure 8 appears to show an annual cycle of convergence in each of the rooms. If the cycle in Figure 8 were broken for SPDV-1 and convergence rates rose sharply and continued to rise, Mr. Parker would predict a fall "soon." However, graphs can be complicated by other variables (for instance, bolting).

The failure mechanism for SPDV-1 was salt from the tops of the pillars on each side of the unit pushing or flowing toward the center of the room. This caused the roof to buckle and fall. Mr. Parker would have liked to inspect SPDV-1 and SPDV-2 after their roof falls, as well as the other closed experimental rooms, but the DOE prohibited access by installing a concrete barricade. For a proper analysis of a rock-fall, it is essential to see the worst, best, and average rooms in order to see a whole range of conditions.

WIPP is not unusual for a deep salt mine in bedded salt. The Cayuga Mine in New York state was a salt mine that had similar problems. In fact it had dozens of roof-falls bigger than SPDV-1. The pillars were too big and pushed into the roof and floor. Reducing the size of the pillars solved the problem. Each large pillar had holes excavated in it and then was divided into 4 smaller pillars to reduce roof-falls.

HOW FAR IN ADVANCE CAN A ROOF FALL BE PREDICTED? One could probably tell with certainty a week or two in advance of a roof-fall, maybe a month or two. Sometimes one could predict earlier when a roof would fall, but other times there are surprises. Because of the different roof support systems in the different rooms there will be a differing ability to predict failure in each room. The different support systems mask effects that are normally used to predict falls. The roofs have probably failed already and are just suspended by the bolts. The DOE believes it can predict failure 18 months in advance. Mr. Parker does not agree.

The Hearing Officer asked if Mr. Parker could give a percentage of confidence on when a roof would fail. Mr. Parker answered that predictability in this science is crude. In some mines without roof bolts and with predictable geology, one could see a break in the convergence curve and predict failure 3 months in advance, but this is not always possible to see from the graphs.

CHAIN REACTION: Stress usually develops along the ribs (sides) of a room. Those bolts along the ribs fail first. One might or might not be able to tell whether the bolts have failed. At this point there would probably be rock- falls along the ribs which would be the initial signs of failure. In some of the Panel 1 rooms the supports are tied together with mesh and cable along the roof and down the sides of the walls. In this case, if there is failure of the bolts on the ribs, the stress could be transferred to the other bolts in the support system and may create a domino effect. Mr. Parker has seen this happen in other mines.

MAINTENANCE: With enough money and effort one could support a room indefinitely. Wooden cribs could slow down a roof-fall, and if one totally backfilled a room the roof might never fall. Waste could be recovered after a roof- fall, but more people would be at risk and it would take much more time and money. Bodies would be recovered after roof-falls. Mr. Parker also testified that such a considerable risk should not be undertaken at WIPP. At WIPP, there are cheaper and safer alternatives to using Panel 1.

Figure A-4-2 from the Permit Application was shown. This is a picture of a mined area underground. Mr. Parker stated that conditions are much worse underground now than when the picture was taken. The best way to handle the situation in Panel 1 would be to not use Panel 1, excavate a new room, stuff it with waste, and seal it. This would be more economical and safer than the DOE's current plan.


In Mr. Parker's 1991 affidavit he stated that there would be at least 6 months of advance warning of a roof-fall. Mr. Parker stated that the degree of prediction was different then. Six months is enough time to evacuate personnel in empty rooms, but if waste emplacement were being scheduled, he would not be giving any such dates.

Immediately after a new support system is installed, maintenance other than visual inspection is not required for some period of time. However, a new system could not be installed if there was a chain reaction type of failure. Maintenance of support systems in unfilled areas of disposal rooms could be performed if there were no unexpected chain reactions. Mr. Parker does not know what the conditions would be like for repairs. The DOE asked whether cost was a factor in the decisions made to prevent roof-falls in the Cayuga mine. It was.

Geotechnical data at WIPP is "good of a kind." Judging from the results of the observations of the Ground Control personnel at WIPP and their plans, Mr. Parker believes his observations are better. Some members of the 1991 expert panel who praised the geotechnical database for WIPP and promoted roof support systems were probably doing so to drum up business! However, the database could be described as better than at most mines. Generally the mine is well run.

If there was sufficient time to replace all the bolts in a roof support system, a chain reaction could be prevented. However, Mr. Parker believes there will be need for maintenance on the newest bolt system installed in Room 7 within the first 2 years after installation. Installation of up to 3 sets of roof bolts has not changed the rate of convergence significantly. The rate can still be measured at WIPP. If the rooms at WIPP were filled within 5 years of excavation, the design would be adequate. Mr. Parker would not, however, recommend this design.

Based on the Figure 8 convergence graph for SPDV-2 Mr. Parker could not have predicted when that roof would fall.

Evidence that support systems are masking roof failure could be such things as heads popping off the roof bolts, bolts falling out, or rib areas falling apart while the convergence point in the middle of the room still appeared to behave normally. Roof bolts can fail without being detected by visual examination when they hang up in the drill hole. There could be more roof bolt failures at WIPP than are detected by visual observation alone.

If waste were emplaced in a room, rock bolts could not be replaced above the waste. A chain reaction and collapse of the roof could take place.

A second fall into the void space of the first roof-fall can occur anywhere from a few minutes to a few years later. There is usually a limit to how far up a series of roof falls will go. Since the most favorable shape for a mine opening in rock salt is a sphere, the falls will approximate this shape. The sphere will be the limit for the zone of tension. At WIPP you will end up with a natural arch interrupted by partings.

At Cayuga, the Mine Safety and Health Administration (MSHA) closed the mine for a month after multiple roof- falls. Mr. Parker has seen MSHA close another mine because of instability. MSHA sometimes called in technical support to evaluate stability problems.

Brine is pressurized in pockets 700 or 800 feet below the WIPP site. Under similar circumstances in European mines, even with a 700-foot distance from the mine, there have been bursts of water and gas. The operations in Europe were more extensive than at WIPP. The same thing is possible at WIPP, but not probable.

METHANE GAS EXPLOSION: If there were a methane gas explosion in the repository, personnel in active areas could be hurt or killed. The severity of any damage would depend on the magnitude of the explosion and the quality of panel seals. There have frequently been methane gas explosions in closed portions of coalmines and in a few salt and potash mines that caused the death or injury of workers in the active parts of the mine.

The problems at WIPP are typical and Mr. Parker has seen similar situations in one or two dozen mines elsewhere. When his recommendations were followed, situations improved.

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