MINING CONDITIONS UNDER CITY OP SCRANTON, PA. 49 MIDDLE BEDS.
HYDE PARK AND PROVIDENCE SECTIONS.
As before mentioned, under Hyde Park and Providence, the middle series of beds, the Diamond, Rock, Big, New County, and Clark (especially the first three of these), are quite thick and the intervening strata are comparatively thin and weak. On account of the failure in the past to columnize pillars, the workings in these beds, where now open, constitute a serious menace to the surface, and this portion of the city will be the most expensive and difficult to protect. However, it should be noted that very large areas of the three uppermost beds have been closed by crushing of the pillars and strata in the past. This condition was observed in parts of the Bellevue, Hyde Park, Hampton, Oxford, Mount Pleasant, Diamond, Brisbin, Cayuga, Yon Storch, Leggetts Creek, and Marvine mines. Where such complete crushing of the pillars, with consequent subsidence of the overlying strata and surface, has taken place in the past, no serious apprehensions need be entertained of future damage to the surface improvements, unless, in the process of mining lower veins, insufficient pillar support is left to carry the overburden and a creep or squeeze takes place. This has been the case recently at the Leggetts Creek mine in mining the lower Dunmore bed at a depth of 700 feet, where was applied the usual though here insufficient rule of leaving about one-third of the coal for support.
Where the workings in these thick and closely lying beds are not closed by a general crush (and no one knows how large or extensive such openings may be) there is always a liability to a repetition of the same kind of subsidence as that which wrecked No. 16 School. In this connection attention is particularly called to the conditions existing under No. 12 School. Here the Diamond bed is very near the surface, within 13 to 40 feet. Second mining is now in progress to win bottom coal formerly left in this bed, and the New County bed is being mined. An attempt is being made to drive openings in the New County bed under openings in the Big bed, but this attempt is not altogether successful. These conditions, we believe, are quite similar to those formerly existing under No. 16 School.
We strongly recommend that the pillars in the Diamond, Rock, Big, and New County beds under this building should not be disturbed, and that the openings in the Diamond, Rock, and Big beds should be filled as promptly as possible. Such filling could easily bo done by drilling one or two bore holes in the school lot. The filling of openings should not be confined to the school lot only, but should extend outside the lot some distance, as there is danger in case of a cave in any seam, of the side pull damaging the building.