A FINAL RULE EXPANDING THE DEFINITION OF HAZARDOUS WASTES WAS PUBLISHED IN THE FEDERAL REGISTER MARCH 29, 1990 AND BECOMES EFFECTIVE SEPTEMBER 25, 1990. THIS REGULATION, WHICH ADDS 25 NEW ORGANIC CONSTITUENTS TO THE TOXICITY CHARACTERISTIC AND REPLACES THE EP TEST WITH THE TCLP, IS EXPECTED TO CLASSIFY AN ADDITIONAL 730 MILLION TONS OF WASTE PER YEAR AS HAZARDOUS. EPA HAS ESTIMATED THAT 15,000 TO 17,000 FIRMS MAY BE AFFECTED, BUT THE NUMBER MAY BE HIGHER, SINCE MOST FACILITIES THAT GENERATE OR MANAGE WASTE WILL HAVE TO, AT A MINIMUM, RE-DETERMINE WHETHER ANY OF THEIR WASTES ARE HAZARDOUS BY THE NEW DEFINITION. THE MAJORITY OF WASTES EXPECTED TO BE HAZARDOUS UNDER THE NEW RULE ARE WASTEWATERS, MANY OF WHICH ARE MANAGED IN SURFACE IMPOUNDMENTS. FACILITIES MUST CEASE USE OF TREATMENT, STORAGE, OR DISPOSAL UNITS MANAGING NEWLY REGULATED WASTES PRIOR TO SEPTEMBER 25, 1990 TO AVOID PERMITTING