Amends the Internal Revenue Code to: (1) make permanent provisions allowing the expensing of environmental remediation costs; (2) revise the definition of "qualified contaminated site" to include toxic as well as hazardous substances; (3) include within the definition of "hazardous or toxic substances" extremely hazardous substances, as defined by Federal law, and petroleum contaminants; and (4) eliminate the recapture of the expensing deduction upon the sale of environmental remediation property.