TO SAVE A SINKING CITY

THE POTENTIAL MINE COLLAPSE BELOW ROCK SPRINGS, WYOMING IS CONSTANTLY VISIBLE AS A RESULT OF SURFACE SUBSIDENCE THAT BEGAN IN 1967. IN RESOLVING THE SUBSIDENCE PROBLEM IT WAS ESTIMATED THAT ABOUT 200 ACRES BENEATH THE BUILT-UP PORTIONS OF THE CITY REQUIRE BACKFILL SUPPORT. HOWEVER, THE MINE VOIDS BENAEATH ROCK SPRING WERE GENERALLY INUNDATED. CONSEQUENTLY, IT WAS PROPOSED THAT BEFORE INITIATING A MAJOR PROJECT A DEMONSTRATION SHOULD BE UNDERTAKEN TO EVALUATE THE FEASIBILITY OF BAKCFILLING THE VOIDS BY A PROCESS DEVELOPED BY DOWELL. THE DOWELL PROCESS IS A BLIND FLUSHING TECHIQUE THAT UTILIZES A COMPLETELY CLOSED SYSTEM BETWEEN THE TOP AND BOTTOM OF THE INJECTION HOLE, PERMITTING CONTINUOUS FLOW OF FLUIDIZED SAND AND WATER INTO THE VOID AT HIGH VELOCITY UNDER PRESSURE. ALTHOUGH THE PROJECT FAILED TO ACHIEVE THE RELATIVELY COMPLETE FILLING OF THE VOIDS WITHIN THE PREDICTED CIRCULAR AREA, IT CLEARLY DEMONSTRATED THAT THE CLOSED SYSTEM HYDRAULIC TECHNIQUE IS CAPABLE OF FILLING A MUCH GREATER PORTION OF THE MINE FROM A SINGLE BOREHOLE THAN OTHER KNOWN TECHNIQUES. THE FAILURE TO ACHIEVE THE PREDICTED DISTRIBUTION IS TO BE ATTRIBUTED MORE TO A LACK OF EXPERIENCE IN THE PLANNING AND EXECUTION OF SUCH A PROJECT THAN TO LIMITATIONS IN THE TECHNIQUE ITSELF. THE DEGREE OF STABILIZATION ACHIEVED, OF COURSE, DEPENDS UPON THE SIZE OF THE REMAINING VOID AND THE DENSITY OF THE IN-PALCE BACKFILL. VOIDS COMPLETELY FILLED WITH THE BACKFILL MATERIAL USED COULD BE EXPECTED TO ALLOW CONSOLIDATION OF FROM 4 TO 12 INCHES, LIMITING POTENTAIL SURFACE SUBSIDENCE TO LESS THAN ONE INCH.

  • Availability:
  • Supplemental Notes:
    • VOL 103 NO 2 PP 74-7, 126-7
  • Authors:
    • Wataha, P J
  • Publication Date: 1972-2

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Filing Info

  • Accession Number: 00233261
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 16 1972 12:00AM