text: of estimated permitted airspace plus an estimate of probable expansion airspace. These estimates are 
  developed annually by engineers utilizing information provided by annual aerial surveys. As of December 31, 
  2004, total available disposal capacity is estimated to be 1.5 billion in-place cubic yards of permitted airspace 
  plus .2 billion in-place cubic yards of probable expansion airspace. Before airspace included in an expansion 
  area is determined to be probable expansion airspace and, therefore, included in our calculation of total 
  available disposal capacity, it must meet our expansion criteria. See Note 3, Accrued LandÑll and 
  Environmental Costs of the Notes to our Consolidated Financial Statements for further information. 
  
  As of December 31, 2004, twelve of our landÑlls meet the criteria for including probable expansion 
  airspace in their total available disposal capacity. At projected annual volumes, these twelve landÑlls have an 
  estimated remaining average site life of 30 years, including probable expansion airspace. The average 
  estimated remaining life of all of our landÑlls is 30 years. 
  
  The following table reÖects the estimated operating lives of our active landÑll sites based on available 
  disposal capacity using current annual volumes as of December 31, 2004: 