Coal Mining in Colorado Springs, Colorado

1 coal

1.1 colorado springs coalfield
1.2 mining
1.3 subsidence , other hazards
1.4 real estate development

coal

colorado springs coalfield

the colorado springs coalfield located in southwestern part of denver basin, lower part of laramie formation ranges 150 200 feet thick, , upper part ranges 100 150 feet thick. lower part of laramie in colorado springs coal field includes alternating beds of fine fine-grained sandstone, claystone, , coal, whereas upper part composed of claystone thin interbeds of fine-grained sandstone.

in 1910, marcus i. goldman designated 3 coal beds in lower part of formation coal beds a–c in ascending order; other unnamed thin , lenticular coal beds present in area. of mines in colorado springs coal field produced coal , b coal beds. coal bed present 30 65 feet above base of formation, , single bed, thick 20 feet locally. elsewhere in coal field, coal bed splits 2 coal beds separated 8 feet of rock; in more extreme cases, bed splits series of 4 5 thin coal beds separated rock partings. coal bed b present 25 50 feet above coal bed a, massive sandstone typically separating 2 coal beds. coal bed b as 13 feet thick locally, although bed more typically 5 feet thick or less throughout of colorado springs coal field. coal bed c lenticular , in places absent. coal bed c present, lies 20 50 feet stratigraphically above coal bed b , less 2 feet thick.

by 1922, there 9 active coal mines, pikeview, keystone, city #1 , #2, old patterson, danville, cottonwood, altitude, , black mariah. year, workers of pikes peak coal company (owner of pikeview mines) complained of working conditions, particularly smoke generated firing shots clear mines. ths common problem state had not been able resolve. state mine inspection department reported company had found solution; shot firer fire shots when mine had been vacated.

over years, there more 16 million tons of coal mined colorado springs coal field.

mining

shaft or lode mining, lithograph, 1866, lithograph julius bien, pikes peak library district collection. interior of coal mine shaft, depicting workers , mining activities.

beginning 1859, area mined coal. there 50 coal mines in colorado springs, in rockrimmon , cragmor - colorado springs country club area. mining in rockrimmon area occurred between 250 500 feet (76 152 m) below surface, while cragmor mines shallow, 30 feet (9.1 m) below surface. deeping upon depth of coal bed, mines entered through vertical mine shafts or through inclined openings.

the mines in rockrimmon area corley, columbine, knights of industry, 3 pikeview, , klondike mines, deepest of klondike mine @ 500 feet. cragmor mines city mine, altitude, williamsville mine, curtis mine, patterson mine, climax mines, conley, busy bee, , danville. country club area mines city #3, keystone, new keystone, rapson, austin bluffs, el paso, , unknown mines. further southeast, near academy , constitution city #4, tudor, , cardiff mines.

coal mined using room , pillar method, in areas of unmined coal acted pillars while coal removed shafts, creating rooms. sometimes, rather leaving pillar support, supporting coal removed. seams of coal 1 fourteen feet deep in colorado springs area.

subsidence , other hazards

subsidence process , effects

of city s 50 abandoned mines, 22 have become hazardous because shallow mines —some no more 30 feet (9.1 m) below surface—that subject sinking under developed land. in study of mine subsidence in colorado springs coal field dames , moore consulting firm in 1985, trough-like subsidence on room-and-pillar mines observed irregular, , authors of report interpreted interior of given subsidence trough undergo varying periods of tension , compression, depending on timing required failure of existing coal pillars , supports. suggested overburden above room-and-pillar mine decreases, trough subsidence series of sinkholes resulting collapse of mine rooms scattered larger depressions (troughs) forming general failure of pillars or mine floor on larger areas.

many of hazardous, abandoned mines near cragmor, such cragmor country club estates had 3,000 residents in late 1980s. there more 2,400 crack , sinkholes in cragmor country club estates area, while there total of 7 in other areas of colorado springs during 1985 study supervised colorado mined land reclamation division. in 2005, there collapse on country club circle threatened 5 houses. because hazardous subsidence area in state, study conducted in 2008 using geophones locate mining tunnels. plan fill in voids sand , gravel.

strategies mitigating risk due sinkholes , subsidence include filling voids, can costly due amount of material needed, , construction techniques structures not prone sinking. strategies managing risk include insurance subsidence , sinkholes.

there hazards due mine openings, drainage of metals or other pollutants mines groundwater, or fires within mines or outside waste banks. there no known occurrences of groundwater contamination or fires, ongoing risks. in april 1979, surface plug of 500-foot klondike mine shaft @ woodman road , i-25 had deteriorated , reopened. 2 mine opening hazards remain @ cragmor-country club , wilson ranch area.

real estate development

by 1950s, coal no longer mined in cragmor area , land developed construction of 3,500 houses, completed in 1960s. then, initial instances of subsidence began, such 1 on mount view lane in 1963. in case, dog died when earth sunk in backyard beneath dog became trapped in falling dirt , died due suffocation. in 1979, earth fell through old mine shaft fourplex on magnolia street in cragmor area, forcing evacuation of residents , requiring means brace building. year, subsidence resulted in 12 7 feet (3.7 2.1 m) sinkhole in park. discovered 31 feet (9.4 m) below surface of park mine shafts , pool slipping shafts. sinkhole filled , pool braced when tons of concrete poured shafts.