PURPOSE:  To evaluate the effects of explosions on specific mine ventilation seals at the NIOSH Lake Lynn Experimental Mine (LLEM) at the request of the Mine Safety and Health Administration (MSHA) and the West Virginia Office of Miners´ Health, Safety and Training (WVOMHST). Accurate forensics from this study will be important for thorough accident interpretation and follow-up recommendations to prevent future occurrences.

RESEARCH SUMMARY:  On January 2, 2006, there was an explosion at the Sago Mine near Tallmansville, WV. The explosion claimed the lives of 12 coal miners. This tragic accident was due to a methane explosion that occurred in an abandoned area of the mine that destroyed the seals that were used to isolate this abandoned area from the active mine workings. MSHA and WVOMHST requested the technical assistance of NIOSH to evaluate the explosion effects on specific seals within the LLEM.

A testing program was instituted by NIOSH-MSHA-WVOMHST developing a joint protocol that would best simulate the seal construction techniques and conditions within the Sago Mine. This work was also relevant to the “Mine Explosion Prevention” project, which is developing improved forensics for investigating explosion accidents. From March through October of 2006, a total of 7 explosion tests were conducted against the full-scale seal designs at the Pittsburgh Research Laboratory's LLEM. The initial tests were to determine if these seals could withstand a 20 pounds per square inch (psi) side-on explosion overpressure as well as a 20 psi head-on reflected explosion overpressure. Federal regulations at that time required seals to withstand a horizontal static load of 20 psi. Later tests with higher level head-on reflected explosion overpressures of 50 psi and upwards of 100 psi were conducted to evaluate the ultimate strengths of these seals. The debris field of each destroyed seal within the LLEM was mapped to compare with investigators´ observations at Sago. Additionally, other typical mine equipment and structures were installed within the LLEM to evaluate the pressure effects on these objects. These included wood crib roof support structures, coated dry-stacked concrete-block ventilation stoppings, a battery charger, manikins, fire sensor boxes, metal conveyor belt hangers, and sets of various types of roof bolt support plates.