**Exhibit 31.2**

 

**CERTIFICATION**

** **

I, Donald C. Heppermann, certify that:

 

1. I have reviewed this quarterly report onForm 10-Q of MarkWest Hydrocarbon, Inc.:

 

2. Based on my knowledge, this quarterlyreport does not contain any untrue statement of a material fact or omit tostate a material fact necessary to make the statements made, in light of thecircumstances under which such statements were made, not misleading withrespect to the period covered by this quarterly report.

 

3. Based on my knowledge, the financialstatements, and other financial information included in this quarterly report,fairly present in all material respects the financial condition, results ofoperations and cash flows of the registrant as of, and for, the periodspresented in this quarterly report.

 

4. The registrant’s other certifying officerand I are responsible for establishing and maintaining disclosure controls andprocedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) for theregistrant and we have:

 

a)              Designed such disclosure controls andprocedures, or caused such disclosure controls and procedures to be designedunder our supervision, to ensure that material information relating to theregistrant, including its consolidated subsidiaries, is made known to us by otherswithin those entities, particularly during the period in which this quarterlyreport is being prepared;

 

b)             Evaluated the effectiveness of theregistrant’s disclosure controls and procedures****and presented in this report our conclusions about the effectivenessof the disclosure controls and procedures, as of the end of the period coveredby this report based on such evaluation**;**and

 

c)              Disclosed in this report any change in theregistrant’s internal control over financial reporting that occurred during theregistrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarterin the case of an annual report) that has materially affected, or is reasonablylikely to materially affect, the registrant’s internal control over financialreporting; and

 

5. The registrant’s other certifying officerand I have disclosed, based on our most recent evaluation of internal controlover financial reporting, to the registrant’s auditors and the audit committeeof registrant’s board of directors (or persons performing the equivalentfunction):

 

a)              All significant deficiencies and materialweaknesses in the design or operation of internal control over financialreporting which are reasonably likely to adversely affect the registrant’sability to record, process, summarize and report financial information;

 

b)             Any fraud, whether or not material, thatinvolves management or other employees who have a significant role in theregistrant’s internal controls over financial reporting.

 

 
| Date:  | August 14, 2003                                                           |
|--------|---------------------------------------------------------------------------|
|   |
|   |
|   | /s/ Donald  C. Heppermann                                                 |   |
|   |                                                                      |
|   | Donald C.  Heppermann                                                     |
|   | Senior Vice  President Finance,   Chief Financial Officer and   Secretary |
|        |                                                                           |  |  |

 

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