WITHIN 30 DAYS OF THE EFFECTIVE DATE OF THIS AGREEMENT, EITHER SAFETY-KLEEN OR MCKESSON (AS THE CONDITIONAL INDEMNITOR OF SAFETY-KLEEN) SHALL PAY $60,000 TO THE EPA HAZARDOUS SUBSTANCE SUPERFUND IN REIMBURSEMENT OF PAST RESPONSE COSTS. INTEREST SHALL BEGIN TO ACCRUE 30 DAYS AFTER THE EFFECTIVE DATE OF THIS AGREEMENT, AND SHALL CONTINUE TO ACCRUE ON THE UNPAID BALANCE THROUGH THE DATE OF PAYMENT. SHOULD MCKESSON FAIL TO PAY THE $60,000 OR ANY ACCRUED INTEREST, SAFETY-KLEEN SHALL PAY ALL OUTSTANDING SUMS. SAFETY-KLEEN SHALL PAY TO U.S. EPA A STIPULATED PENALTY IN THE AMOUNT OF $50 PER DAY THAT SUCH PAYMENT IS LATE.