<ARTICLE> 5
<MULTIPLIER> 1,000
        
                                                          
<PERIOD-TYPE>                   6-MOS                         6-MOS
<FISCAL-YEAR-END>                          DEC-31-1998                   DEC-31-1997
<PERIOD-START>                             JAN-01-1998                   JAN-01-1997
<PERIOD-END>                               JUN-30-1998                   JUN-30-1997
<CASH>                                           6,047                         2,668
<SECURITIES>                                         0                             0
<RECEIVABLES>                                    8,439                         5,431 
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<CURRENT-ASSETS>                                25,405                        14,326
<PP&E>                                         113,538                        87,653
<DEPRECIATION>                                  54,304                        47,081
<TOTAL-ASSETS>                                 158,895                        81,951
<CURRENT-LIABILITIES>                           20,003                        19,899
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<PREFERRED-MANDATORY>                                0                             0
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<OTHER-SE>                                      66,922                        26,151
<TOTAL-LIABILITY-AND-EQUITY>                   158,895                        81,951
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<TOTAL-REVENUES>                                60,857                        52,311
<CGS>                                           44,886                        38,128
<TOTAL-COSTS>                                   54,671                        46,826
<OTHER-EXPENSES>                                     1                          (39)
<LOSS-PROVISION>                                     0                             0
<INTEREST-EXPENSE>                               1,263                         1,630
<INCOME-PRETAX>                                  4,922                         3,894
<INCOME-TAX>                                     1,895                           251
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<NET-INCOME>                                     3,027                         3,643
<EPS-PRIMARY>                                      .24                           .46
<EPS-DILUTED>                                      .23                           .45