62 MINING CONDITIONS UNDER CITY OF SCRANTON, PA.
In addition to this source of supply of filling material, it would probably be found practicable to install handling and crushing machinery at each of the mining operations within the city limits, to pick up refuse material, such as old rock banks, ash banks and slag, and to grade off humps and hills of earth and comparatively soft rock, and to treat this material in the same manner. The cost of handling and flushing such foreign material in connection with the going operations of the several mines, would, of course, be very much less per cubic yard than it would be in the case of an independent plant established for obtaining and handling flushing material elsewhere.
RIVER SAND.
The next source of supply of material for flushing purposes, and one that we deem of considerable importance, is the Lackawanna River. It is a well-known fact that this stream of water carries in suspension large quantities of culm, sand, and loam at all times, and especially during the flood season. Of course it is impossible to determine without careful tests the quantity of this material in cubic yards, but we do not hesitate to express the opinion that there is enough of it, and will continue to be, to justify the establishing of settling basins and of a pumping plant for distributing the material thus impounded to points in the mine workings where artificial pillars are to be inserted.
To utilize this source of supply, it would, in our opinion, be advisable either to purchase, or to procure long-term leases on, river-bottom lands at various points where suitable catch basins could be excavated, and to procure a site for a central pumping plant for the purpose of handling this material. When such a plant is established, arrangements could be made to let down from the catch basins, at points upstream, the accumulated material; this would be carried by the stream to a central basin somewhere within the city limits.
We believe similar impounding basins on a smaller scale might be practicable on Roaring Brook, and that such material, if gathered at a higher elevation, might be flushed to near-by mine workings by gravity.
CITY REFUSE.
Another source of supply of material for flushing purposes would be city ashes and refuse from the streets and catch basins; also material from cellar excavations, grading of streets, parks, etc., which of course would have to be put through a crushing plant and reduced to such a size that it could be handled by flushing. For the proper distribution of the material just mentioned it would be necessary to drill bore holes to the mine workings at convenient points in the city streets and alleys—preferably in the latter, because there would be less inter-