<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY INFORMATION EXTRACTED FROM THE BALANCE SHEET AS
OF SEPTEMBER 30, 1997 AND THE INCOME STATEMENT FOR THE NINE MONTHS ENDED
SEPTEMBER 30, 1997 AND IS QUALIFIED IN ITS ENTIRETY TO SUCH FINANCIAL
STATEMENTS.
</LEGEND>
<MULTIPLIER> 1000
       
                             
<PERIOD-TYPE>                   9-MOS
<FISCAL-YEAR-END>                          DEC-31-1997
<PERIOD-END>                               SEP-30-1997
<CASH>                                           5,400
<SECURITIES>                                         0
<RECEIVABLES>                                   57,100
<ALLOWANCES>                                     2,500
<INVENTORY>                                     14,600
<CURRENT-ASSETS>                                95,700
<PP&E>                                       1,642,900
<DEPRECIATION>                               1,030,400
<TOTAL-ASSETS>                                 725,900
<CURRENT-LIABILITIES>                          103,400
<BONDS>                                              0
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                         1,000
<OTHER-SE>                                     449,600
<TOTAL-LIABILITY-AND-EQUITY>                   725,900
<SALES>                                        425,100
<TOTAL-REVENUES>                               425,500
<CGS>                                          321,700
<TOTAL-COSTS>                                  321,700
<OTHER-EXPENSES>                                     0
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                              15,500
<INCOME-PRETAX>                                 90,100
<INCOME-TAX>                                    34,300
<INCOME-CONTINUING>                             51,100
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                    51,100
<EPS-PRIMARY>                                     0.40
<EPS-DILUTED>                                     0.40