D office decline east portal D Highway 1 Highway 2 Highway 3 Crosscut 4 Crosscut 3 Crosscut 2 Crosscut 1 TEAM AND FRESH AIR BASE MAP vent shaft sump D warehouse North

Team Briefing Statement The Wilmington Mine is an underground limestone mine. Limestone is drilled and blasted from multiple faces. After a face has been mechanically scaled and bolted, LHD’s are used to load the shot rock into haulage trucks for transport to the surface for crushing and screening into various products for the construction aggregates market. All equipment is rubber-tired and diesel-powered. Entries are nominally 10 feet wide by 7 feet high. The mine operates one production shift and one maintenance shift per day, 6 days per week. Regionally, the limestone bed dips slightly to the northwest, but within the mine, the bed undulates, and there are localized areas where the bed dips in other directions. Access to the underground is from the east portal, which is at the level of the limestone bed being mined, and the decline, which is on the west side of the mine and slopes down from the portal, reaching the level of the limestone bed at crosscut 3. The mine roof consists of a 12-foot thick dolomite unit with clay partings every 18 to 36 inches. Use of 6-foot resin bolts on a 5-foot by 5-foot pattern is generally effective for ground support, but the mine has experienced a few significant falls. Ventilation is provided by an 80 horse- power propeller-type exhaust fan located at the top of a 110-foot upcast vent shaft. The fan is not reversible, and the shaft is not equipped with a ladder or any type of conveyance. The mine typically makes between 10,000 and 12,000 gallons of water per day. Water is pumped in two stages; first from a collection point in Crosscut 2 to a sump at the bottom of the decline, and then from the sump to a surface quarry about ¼ mile from the decline portal. There are no other underground mines known to exist in the area, and there has never been any methane detected in the mine. At 8:00 PM yesterday evening, the maintenance shift began normally. The maintenance shift generally consists of a supervisor, an electrician, three mechanics, an oiler, and a warehouse worker. Production mining activities may also be scheduled during a maintenance shift. This practice has become more common lately with increasing demand for stone. At 2:00 AM this morning, the supervisor called to the surface from the underground mine office to report smoke in Highway 2. He said he was leaving the office to investigate. The oiler and the warehouse worker arrived at the surface at 2:35 AM, followed twenty minutes later by the supervisor, who was wearing his self-rescuer. The supervisor said when he left the mine office to investigate, he encountered heavy smoke in Highway 2 north of crosscut 2. Although the smoke prevented him from advancing further to locate the source, it was clear to him that the mine needed to be evacuated immediately. The mine doesn’t have an emergency alarm system. Its up to the supervisor to travel to the various work places and tell the workers to evacuate. He found the oiler and warehouse worker in the warehouse and told them to evacuate. He then continued to search for anyone else who might still be underground. He thought two of the mechanics were working on a stalled loader, and the other mechanic and the electrician were working on a pump, but he was unable to reach any of them before he was forced by heavy smoke to exit the mine. It is now 4:00 AM. There have been no further communications from underground, no one else has exited the mine, and the tag in / tag out board shows four miners unaccounted for; the three mechanics and the electrician. The mine fan and underground mine power have been shut down, locked out and guarded, and a back-up mine rescue team has arrived at the site. The mine map was believed to be accurate when printed about 6 weeks ago. All necessary federal and state agencies and officials have been notified. If your team is willing, we would like you to explore and map all accessible parts of the mine, find and extinguish or seal any fires, account for the missing miners, and rescue any survivors. All materials needed to work this problem are located in the mine and are identified with placards. Good luck.

MINE INFORMATION SHEET Mining & Equipment: Single level stone mine uses conventional room and pillar methods to extract limestone. Shot rock is loaded by LHD and transported to the surface by truck. Average mining height is 7 feet and mine entries are nominally 10-feet wide. All mobile equipment is rubber-tired and diesel-powered. Electricity: Underground electrical power is off and locked out, but power can be restored at any time if necessary. Ventilation: The main fan is an 80 horsepower propeller-type exhaust fan installed at the top of a 110- foot upcast shaft. Electrical power to the fan is off and locked out, but it can be started at any time. Air enters the mine through the east portal and travels roughly counter-clockwise through the workings to the upcast shaft near the top of the decline. Sliding mandoors are provided at various locations to regulate airflow as needed. No CH4, H2S, or SO2 gas has ever been detected in the mine. Water: Water inflows vary with the season. Due to the undulating floor, water can accumulate from time to time in the active workings. These accumulations can reach a considerable depth in some places. Approximately 10,000 to 12,000 gallons per day are pumped in two stages out of the mine. Ground Control: The mine roof consists of a 12-foot thick dolomite unit. At a few locations in the mine, there are clay partings in the roof at spacings of 18 to 36 inches. Use of 6-foot resin bolts on a 5-foot by 5-foot pattern is generally effective for ground support, but the mine has experienced a few significant falls, especially in areas where the partings are prominent. Communications There is a telephone in the underground mine office. Mine Map: The mine map was updated approximately 6 weeks ago. There are no other known mines or oil/gas wells in the area. Explosives: Explosives are available and stored on the surface. Only enough explosives for a day’s use are stored underground on the powder wagon. Materials: All equipment and materials required to work the problem are located in the mine and are identified with placards.

upcast vent shaft; fan on surface D PROBLEM MAP fire out of control pump controls water over knee deep Mine information sheet says water pumping is 2 stage; 1 st stage to sump, then 2 nd stage to surface roof support timbers (enough to post through 8 feet of entry) FAB caved impassable sump pump controls water knee deep loose, unscalable roof loader scaler bolter face drill truck pickup truck roof support timbers (enough to post through 20 feet of entry) truck sissors lift water knee deep decline east portal loader caved tight R sliding door regulator wide open 2 sets of brattices exhausting fan 1 set of brattices gas box pump sump pump telephone T

upcast vent shaft; fan on surface D CONCENTRATIONS OF MINE GASES clear air light smoke, 17% O2, 1200 ppm CO, 15 ppm NO2 moderate smoke, 14% O2, 1600 ppm CO, 20 ppm NO2 heavy smoke, 12% O2, 2200 ppm CO, 20 ppm NO2 very heavy smoke, 10 % O2, 2500 ppm CO, 20 ppm NO2

upcast vent shaft; fan on surface D SOLUTION MAP 1 FAB R 398 T

upcast vent shaft; fan on surface D FAB 12 muck pile from moving caved material bring loader from highway 2 to remove caved material SOLUTION MAP after mucking out caved material with loader, use roof posts to support roof T

upcast vent shaft; fan on surface D FAB 13 SOLUTION MAP 3 D T

upcast vent shaft; fan on surface FAB 14 SOLUTION MAP 4 D T

upcast vent shaft; fan on surface FAB 15 SOLUTION MAP 5 T

upcast vent shaft; fan on surface FAB SOLUTION MAP 6 includes gas box T 16

upcast vent shaft; fan on surface FAB 2022 Fan on after 22 D SOLUTION MAP 7 T 21

upcast vent shaft; fan on surface FAB D 23 SOLUTION MAP 8 T

upcast vent shaft; fan on surface FAB D 24 SOLUTION MAP 9 T

upcast vent shaft; fan on surface FAB D 25 SOLUTION MAP 10 T

upcast vent shaft; fan on surface FAB D 26 SOLUTION MAP 11 water pumped to sump water over knee deep T

upcast vent shaft; fan on surface FAB D SOLUTION MAP 12 water over knee deep Fan on after T 29

upcast vent shaft; fan on surface FAB D 30 SOLUTION MAP 13 T Fan off after 30

5253 upcast vent shaft; fan on surface Placard Map FAB = post1-sided placard = caution tape2-sided placard = chalk on floor six T XX

1Fresh air base 2East mine entrance 3FRONT: Moderate smoke, 14% O2, 1600 ppm CO, 20 ppm NO2, 0% CH4 BACK: Clear air 4FRONT: Water knee deep BACK: Dry ground 5Caved impassible 6TOP: Water over knee deep BOTTOM: Water knee deep BACK: Dry ground 7Loader (miner in cab) 8FRONT: Moderate smoke, 14% O2, 1600 ppm CO, 20 ppm NO2, 0% CH4 BACK: Clear air 9Pump 10FRONT: End water knee deep BACK: Dry ground 11Controls for pump in Crosscut 2 12Pickup truck 13Brattice materials, 2 sets 14Haulage truck 15FRONT: Heavy smoke, 12% O2, 2200 ppm CO, 20 ppm NO2, 0% CH4 BACK: Clear air 16Face drill 17Face 18Roof support posts (enough to support 8 feet of entry) 19Scaler 20Bolter 21Face 22Loose, unscalable roof extends at least 15 feet west from this point 23Loader (door open, idling) 24Caved tight 25Caved tight 26Fire out of control 27Regulator (sliding door, completely open) 28FRONT: End water knee deep BACK: Dry ground 29FRONT: Heavy smoke, 12% O2, 2200 ppm CO, 20 ppm NO2, 0% CH4 BACK: Clear air 30TOP: Water over knee deep BOTTOM: Water knee deep Back: Dry ground 31Door 32Light smoke, 17% oxygen, 1200 ppm CO, 15 ppm NO2, 0% CH4 33End water knee deep 34Door 35Clear air 36Roof support posts (enough to support 20 feet of entry) 37Sump pump controls 38Telephone 39FRONT: Water knee deep BACK: Dry ground 40End of caved impassible 41West mine entrance door 42Heavy smoke, 12% O2, 2200 ppm CO, 20 ppm NO2, 0% CH4 43Scissors lift 44Brattice materials (1 set) 45Haulage truck 46Very heavy smoke, 10% O2, 2500 ppm CO, 20 ppm NO2, 0% CH4 47Fire out of control 48Fire out of control 49Gas box 50End of loose roof unscalable 51FRONT: Very heavy smoke, 10% O2, 2500 ppm CO, 20 ppm NO2, 0% CH4 BACK: Clear air 52FRONT: Very heavy smoke, 10% O2, 2500 ppm CO, 20 ppm NO2, 0% CH4 BACK: Clear air 53Barricade 54FRONT: Blank BACK: Water over knee deep on back 55Sump pump 56Sump Placard Key