EMBANKMENT FAILURE PRODUCES RAPID COOPERATIVE RESPONSE

TRAFFIC ON A MUCH-TRAVELLED SECTION OF INTERSTATE 80, ABOUT 20 MILES NORTH OF SAN FRANCISCO, HAD TO BE PARTIALLY HALTED ON MAY 6, 1969, DUE TO THREATENED SLIDES OF THE SUBSIDENCE OF A DEEP FILL. BY NOON OF MAY 11, 5 OF THE 6 LANES WERE CLOSED; BY 5:30 ALL OF THE SOUTHBOUND LANES AND 2 NORTHBOUND LANES HAD COLLAPSED. ON MAY 13, THE REMAINING LANE ALSO COLLAPSED, A VERTICAL DROP OF ABOUT 50 FEET. THE SLIDE RUPTURED TWO AVIATION FUEL LINES, BUT QUICK ACTION BY 4 FIRE DEPARTMENTS DIVERTED THE FLOW OF FUEL MAKING IT UNNECESSARY TO EVACUATE THE COMMUNITY. A CONTRACT WAS APPROVED FOR IMMEDIATE CONSTRUCTION OF A BY-PASS AT AN ESTIMATED COST OF $350,000 IN AN EFFORT TO RESTORE TRAFFIC SERVICE AS RAPIDLY AS POSSIBLE. THE DETOUR WAS TO BE APPROXIMATELY 2400 FT LONG WITH 6 12-FOOT WIDE LANES. THE NEW DETOUR WAS OPEN TO TOTAL TRAFFIC OPERATION ON MAY 18, JUST 6 DAYS LATER. THE EMBANKMENT SLIPOUT RESULTED FROM WEAKENED FOUNDATION SOILS DUE TO UNPRECEDENTED RISE IN WATER TABLE ELEVATION. THE SUBSURFACE OVER WHICH THE FILL WAS CONSTRUCTED HAD BEEN EXAMINED IN 1954 AND, WHEN NO APPRECIABLE AMOUNT OF WATER WAS FOUND, THE FOUNDATION WAS JUDGED ADEQUATE; THE EMBANKMENT WAS OF A DRY, WELL-COMPACTED HIGH-QUALITY MATERIAL. FOR PERMANENT CORRECTION OF THE SLIDE AREA, IT WILL BE NECESSARY TO DRILL TWO LINES OF WELLS PARALLEL TO THE ROADWAY, ONE ABOVE THE DETOUR TOE AND ONE BELOW BUT IN THE VICINITY OF THE ORIGINAL TOE EMBANKMENT. THE WELLS WILL BE 3 FEET ON 4-FOOT CENTERS, BILLED FOR CONTINUOUS INNER CONNECTION, SUNK TO DEPTHS BETWEEN 45 AND 50 FEET. UPHILL WELLS ARE TO BE INTERCEPTED BY HORIZONTAL DRAINS AND LOWER DRAINS ARE TO BE DRAINED BY PERFORATED PIPE IN GRAVEL BEDS. TO INCREASE STABILITY OF THE EMBANKMENT, A COMPACTED BEAM MUST BE CONSTRUCTED ABOUT 25 FEET HIGH AND 50 FEET BEYOND THE SLIDE.

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  • Supplemental Notes:
    • Vol 101, No 2, PP 68-70, 1 FIG, 3 PHOT
  • Authors:
    • Labernik, J W
  • Publication Date: 0

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  • Accession Number: 00232818
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Apr 16 1970 12:00AM