KNOXVILLE, Tenn. (AP) - A consultant's report says a massive
coal ash spill in Tennessee resulted from a combination of factors
that developed over five decades of operation.
      Engineer Bill Walton of AECOM USA Inc. told a news conference
Thursday that the huge coal ash storage facility at the Tennessee
Valley Authority's Kingston Fossil Plant was "on the verge of
failure" for some time before it actually collapsed in December.
      But he said it took a combination of elements - from the high
water content of the ash to the increasing height of the ash pile
to the construction of sloping dikes over wet ash - that led to the
release of more than 5 million cubic yards of ash into the Emory
River and a lakeside community.
      Walton noted in particular the existence of a 6-inch thick
bottom layer of ash and silt or "slime" that began to creep and
propelled the earthen structure's collapse.