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A Quarterly Publication of the Division of Geological Survey Fall 1995 THE HAZARDS OF MINE SUBSIDENCE by Douglas L. Crowell ine subsidence, like an earthquake, is a showed that the Murray Hill No. 2 mine is partly geologic hazard that can strike with little overlain by unconsolidated material (clays, silts, Mor no warning and can result in very costly and minor lenses of sands and gravels) ranging damage. Mine subsidence, unlike an earthquake, from 23 to 53 feet in thickness; most range from 40 generally affects very few people. But, when a mine to 50 feet thick. Bedrock between the unconsoli- collapses under an interstate highway, many lives dated material and the mine void includes and industries are affected. On Saturday, March 4, interbedded sandy shale and shaly sandstone 10 to 1995, at about 7 p.m., mine subsidence caused a 25 feet thick. According to a 1995 report by Hoffman portion of the eastbound lane of Interstate Route 70 and others, the Upper Freeport coal was 5 to 7 feet (I-70) in Guernsey County to collapse. This subsid- thick and underlain by soft clay. ence event and the ensuing repair work closed the Between the first subsidence in March 1994 eastbound and westbound lanes of I-70 between and completion of the repair work on I-70 in Au- March 4 and August 16, 1995. Approximately 3.4 gust 1995, about eight subsidence events, including million vehicles using I-70 had to be rerouted onto Interstate Route 77 and U.S. Route 40, a two-lane 0 0.5 1 mile highway, through the community of Old Washing- 0 1 kilometer I-77 ton. According to Renee Payette, Project Engineer for the Ohio Department of Transportation (ODOT), the cost of the repair work has been estimated at collapse area $3.8 million. (Murray Hill No. 2 mine) The I-70 collapse occurred over a portion of the CAMBRIDGE Murray Hill No. 2 coal mine, located about 41/2 miles east of the interchange of I-70 and I-77 in Center Township, Guernsey County. This mine, operated by the Akron Coal Company, was opened I-70 in 1912 and abandoned in August 1935. A report by I-70 the State Inspector of Mines stated that the Murray Hill No. 2 mine used a slope opening 125 feet in length to mine the Upper Freeport (No. 7) coal, which was 5 to 51/2 feet thick. The style of mining was room and pillar, using double main and cross entries developed in a somewhat regular pattern. Many entries were developed at right angles; how- I-77 ever, some entries were developed at odd angles, so that some rooms and pillars were quite variable in shape and dimension. Generally, the cross entries BYESVILLE are every 440 feet, the rooms are 30 feet wide and up to 400 feet long, breakthroughs are every 60 to 80 feet, and the pillars are 30 feet wide. The State Location of March 1995 mine collapse along I-70 in Guernsey County. Black areas represent Inspector of Mines stated in a 1913 report that known extent of underground coal mines in the region. electric coal-cutting machines and motor and mule haulage were used in this mine. Because mules the subsidence of March 4, 1995, occurred along a were used for coal haulage, the height of the entries quarter-mile stretch of I-70. Stabilization of the was enlarged by removing some of the roof or floor subsidence required drilling nearly 2,200 boreholes, rock to provide a working height sufficient to ac- averaging 66 feet deep, on approximate 12-foot commodate the mules. A 1914 report by the State centers along 1,800 feet of I-70. The top halves of Inspector of Mines indicates that some miners in these holes were 8 inches in diameter and drilled to the Murray Hill No. 2 mine were involved in pillar bedrock. The bottom halves of the holes were 6 work. A common practice in Ohio deep mines, inches in diameter and drilled into either a pillar of prior to abandonment of a portion of the mine, was coal or the mined-out area. Following drilling, the to mine the pillars of coal that provide roof support mined-out area and the drill holes were filled with during mining. It is suspected that many pillars in 30,385 tons of grout (18,740 tons of fly ash and the Murray Hill No. 2 mine had been removed prior 11,645 tons of cement, sand, and gravel). In addi- to abandonment. tion, two reinforced-concrete land bridges, 110 feet Instability beneath I-70 was first indicated on and 700 feet long, respectively, were constructed on March 16, 1994, when minor subsidence occurred the westbound lanes of I-70 to protect the highway along the westbound lane. Between April and De- from subsidence due to collapse voids in the uncon- cember 1994, ODOT drilled 49 boreholes along I-70 solidated material underlying the westbound lanes. overlying the Murray Hill No. 2 mine. These borings These collapse voids are a result of mine-roof col- continued on page 3 Fall 1995 2 From The State Geologist... Thomas M. Berg OUR ROLE IN FORMING PUBLIC POLICY I recently had the privilege of speaking to a mixed audience on a Saturday morning at Miami University here in Ohio. The audience included people from the general public who had an interest in science, Thomas M. Berg, Division particularly geology, but it was not an audience of other geologists. I was not preaching to the choir, as Chief and State Geologist sometimes happens. Most gratifying was the large number of high-school students present. My general theme was the importance of geology and minerals in our everyday lives and the urgent need to increase general public awareness about geological issues. I began by poking a little fun at the various images that people have of geologists and what geologists do. There is the rugged outdoorsman image of geologists trudging through uncharted terrains in search of who knows what. There is the crusty prospector image. There is the pallid, bespectacled, white-lab-coat scientist image as well. Rarely does anyone have the image of a geologist as one who spends time in the State House or on Capitol Hill trying to educate legislators about geoscience issues or pressing for legislation that clearly reflects geologic facts. Rarely do we have the image of the geologist testifying before legislative committees or serving on vital advisory commissions or committees. In fact, there are geologists who do spend a lot of time working with legislators and serving in A quarterly publication of the advisory capacities. Most people just never hear about those geologists. Ohio Department of Natural Resources As I spoke to the people in that audience, I particularly tried to encourage the young people that geology Division of Geological Survey is a worthwhile career, but that being a geologist today cannot continue in the prevailing images. I tried to 4383 Fountain Square Drive Columbus, Ohio 43224-1362 encourage them that being a geologist is terribly important now, and that geologists should have a significant impact on the reshaping of our society as we head toward the next millennium. Whether we like it or not, the (614)265-6576 functions and concerns of geologists (and therefore, their images) must change as the general public and as (614)447-1918 (FAX) government leaders question or change their own positions on scientific research, environmental problems, e-mail: [email protected] and mineral economics. Ohio Geology is a free publication. To Many state government geological surveys, and the U.S. Geological Survey, have come under close become a subscriber please contact the scrutiny as government is being “reinvented.” Some state surveys and the USGS have been threatened with Division of Geological Survey at the above abolishment. It is a sad state of affairs when legislators and government policy-makers fail to perceive the address, phone numbers, or e-mail. present urgent need for strong government-supported geological agencies. Today, the State of Ohio faces increasingly serious geological concerns including water supplies, energy independence, waste manage- Editor: Michael C. Hansen ment, geological hazards, zoning and land-use planning, construction materials availability, and a host of Layout/Design: Lisa Van Doren environmental matters. New ground-water supplies need to be identified and aquifers need to be mapped to protect water quantity and quality. Coal, oil, and gas are precious fossil energy resources that need to be located and characterized systematically. Municipal-, hazardous-, and nuclear-waste management issues Administration/State Geologist need to be addressed in light of the best possible geologic information. Urban and suburban development is (614)265-6988 greatly expanding in Ohio and needs to be managed in balance with development of our rich mineral heritage. Geologic Records Center We are becoming increasingly aware of geologic hazards including earthquakes, sinkholes, landslides, coastal (614)265-6576 or (614)265-6585 erosion, indoor radon, and abandoned-mine collapse (see article by Doug Crowell in this issue). All of these Bedrock Geology Mapping Group growing geological concerns require a strong state geological survey. In addition, the value of fossil fuels and (614)265-6473 industrial minerals extracted in Ohio during 1994 amounted to $1.816 billion. The geological survey provides the basic data on the location, quantity, and quality of these resources. A strong, efficient, effective, and Cartography & Editing Group (614)265-6593 objective state geological survey is required so that legislators and policy-makers will have the impartial geologic information needed to make today’s heavy-duty environmental and economic decisions.

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