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                                                                    EXHIBIT 24.2

                                POWER OF ATTORNEY

                  KNOW ALL MEN BY THESE PRESENTS, that the undersigned director
of OHM Corporation, an Ohio corporation, hereby constitutes and appoints James
L. Kirk and Pamela K.M. Beall, and each of them, as the true and lawful attorney
or attorneys-in-fact, with full power of substitution and revocation, for the
undersigned and in the name, place and stead of the undersigned, to sign on
behalf of the undersigned a Registration Statement on Form S-8 with respect to
the Retirement and Incentive Compensation Plan, pursuant to the Securities Act
of 1933 and to sign any and all amendments or supplements to such Registration
Statement, and to file the same, with all exhibits thereto, and other documents
in connection therewith, with the Securities and Exchange Commission, granting
to said attorney or attorneys-in-fact, and each of them, full power and
authority to do so and perform each and every act and thing requisite and
necessary to be done in and about the premises, as fully to all intents and
purposes as the undersigned might or could do in person, hereby ratifying and
confirming all that said attorney or attorneys-in-fact or any of them or their
substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

                  Executed as of this 22nd day of January 1997.

                                     /s/ William P. Hulligan
                                     --------------------------------
                                     William P. Hulligan
                                     Director





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