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 Exhibit 10.1  

 EXECUTION  

 
    FIRST AMENDMENT TO CREDIT AGREEMENT    
    

        THIS FIRST AMENDMENT TO CREDIT AGREEMENT (this "Amendment") is entered into as of
January 28, 2009 (the "First Amendment Signing Date"), among MARKWEST ENERGY PARTNERS, L.P., a Delaware limited partnership, as borrower
(the "Borrower"), the undersigned Guarantors (collectively, the "Guarantors"), ROYAL BANK OF CANADA, as
Administrative Agent and Collateral Agent for the Lenders parties to the hereinafter defined Credit Agreement (in such capacities, the "Administrative
Agent" and "Collateral Agent," respectively) and as L/C Issuer, the undersigned Agents, Required Lenders and New Lender. 

        Reference
is made to the Credit Agreement dated as of February 20, 2008 among Borrower, the Administrative Agent, the Collateral Agent, the Syndication Agents, the Documentation
Agents and the Lenders parties thereto (the "Credit Agreement"). Unless otherwise defined in this Amendment, capitalized terms used herein shall have
the meaning set forth in the Credit Agreement; all section,
exhibit and schedule references herein are to sections, exhibits and schedules in the Credit Agreement; and all paragraph references herein are to paragraphs in this Amendment. 

        Borrower
repaid in full the Term Loans and pursuant to Section 2.02 of the Credit Agreement, the Term Loan Commitment has been
reduced to zero and cancelled and no amount of Term Loans may be reborrowed. 

 RECITALS  

         A.    The Borrower has proposed entering into a joint venture, through its Wholly-Owned Subsidiary, MarkWest Liberty Gas Gathering, L.L.C.,
 with M&R MWE
Liberty, L.L.C., to form a Delaware limited liability company to be known as MarkWest Liberty Midstream & Resources, L.L.C. ("MWLM&R"),
which will engage in natural gas gathering and processing and natural gas liquids fractionation, transportation and marketing within the Appalachian Basin. Upon consummation of the transactions
contemplated by the MWLM&R Contribution Agreement (as such term is defined below), MWLM&R will be 60% owned indirectly by Borrower. Borrower has requested certain amendments to the Credit Agreement to
permit the investment in MWLM&R and to exclude MWLM&R from being considered a Subsidiary for various purposes of the Credit Agreement and the Loan Documents. The Required Lenders are willing, on the
terms and conditions set forth herein, to amend the Credit Agreement as hereinafter set forth. 

        B.    One of the terms of the Credit Agreement being amended is the covenant that would require MWLM&R to guarantee and pledge its
assets to secure
Indebtedness owing under the Credit Agreement. To permit the Borrower to form MWLM&R more than 30 days prior to the First Amendment and Increase Effective Date (as such term is defined below),
Borrower has requested a waiver of the covenant in Section 6.14 of the Credit Agreement that would otherwise require MWLM&R to guarantee and
pledge its assets to secure Indebtedness owing under the Credit Agreement within 30 days of its formation. The Required Lenders are willing, on the terms and conditions set forth herein, to
waive such covenant as hereinafter set forth in Paragraph 3. 

         C.    Pursuant to Section 2.15(a) of the Credit Agreement, upon notice to the
Administrative
Agent, Borrower has the right to cause from time to time an increase in the Aggregate Revolver Commitments by allowing one or more Lenders to increase their respective Revolver Commitment (such
Lenders being referred to herein as the "Increasing Lenders") or to solicit Eligible Assignees to become Revolver Lenders (each solicited Eligible
Assignee who becomes a Revolver Lender being referred to herein as the "New Lender"), subject to the limitations contained in such  Section 2.15(a)
. The Borrower has requested an increase in the Aggregate Revolver Commitment of $100,000,000 (or such greater
 

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(but
not exceeding $200,000,000 in any event) or lesser amount as may be committed) and the Lenders and New Lender whose signatures appear below on this Amendment and which are designated as
"Increasing Lenders" or "New Lender" have agreed to increase their respective Revolver Commitment as set forth on Amended Schedule 2.01 attached
to this Amendment. 

        Accordingly,
for adequate and sufficient consideration, the parties hereto agree, as follows: 

        Paragraph 1.    Amendments.    Effective
as of the First Amendment and Increase Effective Date (as defined in Paragraph 4 below), the Credit Agreement is amended as follows: 

        Paragraph 1.1    Definitions.    Section 1.01
of the Credit Agreement is amended as follows: 

        (a)   The
following definitions are amended in their entirety to read as follows: 

        "Aggregate Commitments means on and after the First Amendment and Increase Effective Date, the sum of (i) the Aggregate Revolver
Commitments as of the Closing Date which were $350,000,000 and (ii) the Initial Revolver Commitment Increase Amount of  $85,600,000, for a total
Aggregate Commitments as of the First Amendment and Increase Effective Date of  $435,600,000." 

        "Agreement means this Credit Agreement, as amended by the First Amendment." 

        "Base Rate means for any day a fluctuating rate per annum equal to the highest of (a) the Federal Funds Rate plus
1/2 of 1%, (b) the Prime Rate for such day, and (c) the Eurodollar Rate (which shall never be less than 2.00% per annum) for a one-month Interest Period on
such day (or if such day is not a Business Day, the immediately preceding Business Day) plus one and one-quarter percent (1.25%); provided
that, for the avoidance of doubt, (i) if Base Rate is
determined using the Eurodollar Rate in clause (c) above, the appropriate margin set forth in the pricing grid in the definition of "Applicable Rate" under the Base Rate column will be added to
the amount calculated pursuant to clause (c) above for purposes of calculating interest accruing on each Base Rate Loan and (ii) the Eurodollar Rate for any day shall be based on the
rate appearing on the LIBOR I screen (or any successor thereto) that displays an average British Bankers Association Interest Settlement Rate for deposits in Dollars at approximately 11:00 a.m.
(London time) on such day. Any change in the Base Rate due to a change in the Prime Rate, Federal Funds Rate or the Eurodollar Rate shall be effective automatically and without notice to Borrower or
any Lender on the effective date of such change in the Prime Rate, Federal Funds Rate or Eurodollar Rate, respectively." 

        "Consolidated Net Income means, for any period, for the Borrower and its Subsidiaries on a consolidated basis, the net income or net loss
of the Borrower and its Subsidiaries from continuing operations, provided that there shall be excluded from such net income (to the extent otherwise included therein): (a) the income (or loss)
of any entity (other than a consolidated Subsidiary) in which the Borrower or any Subsidiary has an ownership interest, except to the extent that any such income has been actually received by the
Borrower or such Subsidiary in the form of cash dividends or similar cash distributions (or in the form of a deemed distribution to the extent cash flow has been utilized to pay for Capital
Expenditures in the case of Starfish Pipeline Company, LLC only and in a maximum annual amount not to exceed $2,000,000); (b) net extraordinary gains and losses (other than, in the case
of losses, losses resulting from charges against net income to establish or increase reserves for potential environmental liabilities and reserves for exposure under rate cases), (c) any gains
or losses attributable to non-cash write-ups or write-downs of assets, (d) proceeds of any insurance on property, plant or equipment other than business interruption
insurance, (e) any gain or loss, net of taxes, on the sale, retirement or other disposition of assets (including the capital stock or other equity ownership of any other Person, but excluding
the sale of inventories in the ordinary course of business), and (f) the cumulative effect of a change in accounting principles; provided,
however, notwithstanding whether MWLM&R is treated as a consolidated Subsidiary for financial reporting and accounting purposes generally, it 

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shall
not be treated as a consolidated Subsidiary for purposes of computing Consolidated Net Income as used in this Agreement and the MWLM&R income actually received by the Borrower or a Subsidiary in
the form of cash dividends or similar cash distributions shall be included in (a) above." 

        "Eurodollar Rate means for any Interest Period with respect to any Eurodollar Rate Loan a per annum rate described below;  provided such rate shall never be less
than 2.00% per annum: 

        (a)   the
rate per annum equal to the rate determined by the Administrative Agent to be the offered rate that appears on the page of the LIBOR I screen (or any successor
thereto) that displays an average British Bankers Association Interest Settlement Rate for deposits in Dollars (for delivery on the first day of such Interest Period) with a term equivalent to such
Interest Period, determined as of approximately 11:00 a.m. (London time) two Business Days prior to the first day of such Interest Period, or 

        (b)   if
the rate referenced in the preceding subsection (a) is not available, the rate per annum determined by the Administrative Agent as the rate of interest
(rounded upward to the next 1/100th of 1%) at which deposits in Dollars for delivery on the first day of such Interest Period in same day funds in the approximate amount of the Eurodollar Rate
Loan being made, continued or converted by the Administrative Agent and with a term equivalent to such Interest Period would be offered by the Administrative Agent's London Branch to major banks in
the offshore Dollar market at their request at approximately 11:00 a.m. (London time) two Business Days prior to the first day of such Interest Period." 

        "Lender has the meaning specified in the introductory paragraph hereof and, as the context requires, includes the L/C Issuer and New
Lender." 

        "Lender Hedging Agreement means a Swap Contract between the Borrower or any of its Subsidiaries and a Lender or an Affiliate of a Lender;
and for the avoidance of doubt MWLM&R is not a Subsidiary and no Swap Contract with MWLM&R will be a Lender Hedging Agreement. In addition, for the avoidance of doubt, all Swap Contracts in existence
on the Closing Date between the Borrower or any of its Subsidiaries and any Lender or any Affiliate of a Lender shall constitute Lender Hedging Agreements." 

        "Loan Party means each of the Borrower, each Guarantor, and each other entity that is an Affiliate of the Borrower that executes one or
more Loan Documents; provided, however that MWLM&R shall not be considered a Loan Party for purposes of this Agreement or any Loan Document solely as a
consequence of MWLM&R executing an Acknowledgment of Pledge to evidence its acknowledgment of the pledge by MarkWest MWLM&R Member of its 60% ownership interest in MWLM&R." 

        "Material Project means the construction or expansion of any capital project of Borrower, any Subsidiary or MWLM&R, the aggregate capital
cost of which exceeds $20,000,000." 

        "Maturity Date means (a) February 20, 2012, or (b) such earlier effective date of any other termination,
cancellation, or acceleration of the Aggregate Commitments under this Agreement." 

        "Revolver Commitment means, as to each Revolver Lender, its obligation to make Revolver Loans to the Borrower pursuant to  Section 2.01 and to purchase
participations in L/C Obligations pursuant to Section 2.14,
in an aggregate principal amount at any one time outstanding not to exceed the amount stated beside such Revolver Lender's name on the most-recently amended  Schedule 2.01 to this Agreement
(which amount is subject to increase, reduction, or cancellation in accordance with the Loan Documents) and
collectively for all Revolver Lenders an amount (subject to increase, reduction or cancellation as herein provided) equal to $435,600,000

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(collectively,
the Revolver Commitments of all the Revolver Lenders herein the "Aggregate Revolver Commitments")." 

        "Senior Unsecured Notes means collectively (i) the 6.875% Series A and Series B Senior Notes due 2014 of the Borrower
and MarkWest Energy Finance Corporation, as Issuers, in the original principal amount of $225,000,000 issued pursuant to an Indenture dated October 25, 2004 among the Borrower, its Subsidiaries
party thereto and Wells Fargo Bank, National Association, as trustee, (ii) the 8.5% Series A and Series B Senior Notes due 2016 of the Borrower and MarkWest Energy Finance
Corporation, as Issuers, in the original principal amount of $275,000,000 issued pursuant to an Indenture dated July 6, 2006 among the Borrower, its Subsidiaries party thereto and Wells Fargo
Bank, National Association, as trustee, and (iii) the 8.75% Series A and Series B Senior Notes due 2018 of the Borrower and MarkWest Energy Finance Corporation, as Issuers, in the
original principal amount of $500,000,000 issued pursuant to an Indenture dated April 15, 2008 among the Borrower, its Subsidiaries party thereto and Wells Fargo Bank, National Association, as
trustee." 

        "Subsidiary of a Person means a corporation, partnership, joint venture, limited liability company or other business entity of which a
majority of the shares of securities or other interests having ordinary voting power for the election of directors or other governing body (other than securities or interests having such power only by
reason of the happening of a contingency) are at the time beneficially owned, or the management of which is otherwise controlled, directly or indirectly through one or more intermediaries, or both, by
such Person. Unless otherwise specified, all references herein to a "Subsidiary" or to "Subsidiaries"
shall refer to a Subsidiary or Subsidiaries of the Borrower; provided, however, unless otherwise indicated the term
"Subsidiary" and "Subsidiaries" shall exclude MWLM&R and any Subsidiaries of MWLM&R." 

        "Triggering Sale means receipt of any Insurance Payment and any Disposition (including sales of stock or other equity interests in
Subsidiaries or MWLM&R and Dispositions by MWLM&R of all or substantially all of its assets) (other than a Disposition permitted by  Section 7.07(a) or (b)
 or any Disposition relating directly to the Merger Transaction) by the
Borrower or any Subsidiary of the Borrower (or MWLM&R in connection with the sale of all or substantially all of its assets) to any other Person (other than to the Borrower or to a Wholly-Owned
Subsidiary of the Borrower) with respect to which the Net Cash Proceeds realized by the Borrower or any Subsidiary (or, in the case of a Disposition by MWLM&R of all or substantially all of its
assets, the MarkWest MWLM&R Member's pro rata share of such Net Cash Proceeds), for such Disposition, when aggregated with the Net Cash Proceeds from all such other Dispositions by the Borrower, any
of its Subsidiaries and MWLM&R occurring since the Closing Date and all Insurance Payments received by the Borrower or
any of its Subsidiaries since the Closing Date, equals or exceeds the Threshold Amount. The portion of the Net Cash Proceeds in excess of the Threshold Amount is herein called the
"Reduction Amount." 

        (b)   The
following definitions are inserted alphabetically into Section 1.01 of the Credit Agreement: 

        "First Amendment means that certain First Amendment to Credit Agreement dated as of January 28, 2009 but effective as of the First
Amendment and Increase Effective Date, among the Borrower, the Guarantors, Royal Bank of Canada, as Administrative Agent and Collateral Agent, the Required Lenders and the New Lender;  provided that the
waiver set forth in Paragraph 3 thereof shall become effective as of
January 28, 2009 if the First Amendment has been consented to by Required Lenders." 

        "First Amendment and Increase Effective Date means the date the First Amendment and the increase in the Aggregate Revolver Commitments
provided for therein by their terms becomes effective among the parties thereto." 

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        "Increasing Lenders means each of Royal Bank of Canada, JPMorgan Chase Bank, N.A., U.S. Bank National Association, Deutsche Bank Trust
Company Americas, Compass Bank, Wachovia Bank, National Association and Morgan Stanley Bank who have agreed to increase their respective Revolver Commitment pursuant to  Section 2.15(a) in
the amounts set forth on Amended Schedule 2.01 attached to the First
Amendment." 

        "Initial Revolver Commitment Increase Amount means an aggregate $85,600,000 increase in
the Aggregate Revolver Commitments of the Lenders, allocated among the Increasing Lenders and New Lender as set forth on Amended Schedule 2.01
attached to the First Amendment." 

        "MarkWest MWLM&R Member means MarkWest Liberty Gas Gathering, L.L.C., a Delaware limited liability company." 

        "MWLM&R means MarkWest Liberty Midstream & Resources, L.L.C., a Delaware limited liability company, whose membership interest will
be owned sixty percent (60%) by the MarkWest MWLM&R Member, and forty percent (40%) by the NGP MWLM&R Member upon consummation of the transactions contemplated by the MWLM&R Contribution Agreement." 

        "MWLM&R Available Cash means "Available Cash" as defined in the MWLM&R LLC Agreement." 

        "MWLM&R Contribution Agreement means that certain Contribution Agreement dated as of January 22, 2009 among the MarkWest MWLM&R
Member, the NGP MWLM&R Member and MWLM&R." 

        "MWLM&R LLC Agreement means that certain Amended and Restated Limited Liability Company Agreement of MWLM&R dated as of the First
Amendment and Increase Effective Date." 

        "MWLM&R Services Agreement means that certain Services Agreement dated as of the First Amendment and Increase Effective Date, among
Hydrocarbon, the MarkWest MWLM&R Member and MWLM&R." 

        "New Lender means Barclays Bank PLC, who has agreed to become a Revolver Lender and have a Revolver Commitment pursuant to  Section 2.15(a) in the
amounts set forth on Amended Schedule 2.01 attached to the First
Amendment." 

        "NGP MWLM&R Member means M&R MWE Liberty, LLC, a Delaware limited liability company." 

        "Prime Rate means for any day, the rate of interest in effect for such day as publicly announced from time to time by the Administrative
Agent as its "prime rate." Such rate is a rate set by the Administrative Agent based upon various factors including the Administrative Agent's costs and
desired return, general economic conditions and other factors, and is used as a reference point for pricing some loans, which may be priced at, above, or below such announced rate." 

        "Senior Note Indenture means collectively each indenture pursuant to which any of the Senior Unsecured Notes have been issued." 

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        (c)   The
pricing grid in the definition of the term "Applicable Rate" is deleted and the following is substituted therefor: 

													
	Pricing

Level

 
	 	Total Leverage Ratio 	 	Commitment

Fee

+ (basis points) 	 	Letter of Credit and

Eurodollar Rate

+ (basis points) 	 	Base Rate

+ (basis points) 	 
	1	 	Less than 3.75 to 1.00	 	 	37.5	 	 	250.0	 	 	150.0	 
	
2	
 	
Less than 4.25 to 1.00 but equal to or greater than 3.75 to 1.00	
 	
 	
37.5	
 	
 	
275.0	
 	
 	
175.0	
 
	
3	
 	
Less than 4.75 to 1.00 but equal to or greater than 4.25 to 1.00	
 	
 	
50.0	
 	
 	
300.0	
 	
 	
200.0	
 
	
4	
 	
4.75 to 1.00 or greater	
 	
 	
50.0	
 	
 	
325.0	
 	
 	
225.0	
 

        Paragraph
1.2    Section 2.04(b)(iv).    Section 2.04(b)(iv) of the Credit
Agreement is amended to read in its entirety as follows: 

        "(iv) The
prepayments provided for in this Section 2.04(b) shall be applied as follows,  unless a Default or Event of Default has occurred and is
continuing or would arise as a result thereof (whereupon the provisions of  Section 2.11(d) shall apply): as a repayment of the Revolver Principal Debt; provided that such
repayment of Revolver Principal Debt will not result in or require a corresponding reduction in the Aggregate Revolver Commitments; provided further,
however, if Net Cash Proceeds in excess of 25% of Borrower's consolidated assets (valued as of the close of the then most recent fiscal quarter-end) are or would be
received in connection with any Triggering Sale and on a pro forma basis the Borrower would not be in compliance with the financial covenants set forth in  Section 7.15 taking such Triggering
Sale (or the events giving rise to such Triggering Sale) into account, then the Borrower shall use 100% of
such Net Cash Proceeds to reduce the Aggregate Revolver Commitments (with a corresponding reduction in the Revolver Principal Debt in an amount equal to the amount by which the Revolver Principal Debt
exceeds the reduced Aggregate Revolver Commitments) until the Revolver Principal Debt is reduced to zero at which point no further prepayment of Revolver Principal Debt using the Net Cash Proceeds
from such Triggering Sale is required; provided, however, notwithstanding whether MWLM&R is treated as a consolidated Subsidiary for financial reporting
and accounting purposes generally, the MarkWest MWLM&R Member's proportionate share of MWLM&R's assets shall be included in the Borrower's consolidated assets for purposes of this Section." 

        Paragraph 1.3    Section 2.13.    Section 2.13
of the Credit Agreement is amended in its entirety to read as follows: 

        "2.13    Pari Passu Lien Securing Lender Hedging Agreements and Banking Service
Obligations.    All Obligations arising under the Loan Documents, including, without limitation, Obligations under this Agreement, Banking Service Obligations and
Obligations under any Lender Hedging Agreement (but not Indebtedness of the Borrower or any of its Subsidiaries owing to any non-Lender or non-Lender Affiliate which enters
into a Swap Contract with the Borrower or any of its Subsidiaries), shall be secured pari passu by the Collateral. For the avoidance of doubt, no
Indebtedness of MWLM&R owing to any Lender, any Lender-Affiliate, any non-Lender or any non-Lender Affiliate party to a Swap Contract with MWLM&R shall be secured by the
Collateral. No Lender or any Affiliate of a Lender shall have any voting rights under any Loan Document as a result of the existence of obligations owed to it under any such Lender Hedging Agreement
or as a result of any Banking Service Obligation being owed to it." 

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        Paragraph 1.4    Section 2.15(a).    The
first sentence of Section 2.15(a) of the Credit Agreement is amended in its entirety to read as follows: 

        "Upon
notice to the Administrative Agent and subject to the Administrative Agent's consent (which shall not be unreasonably withheld or delayed), the Borrower may request, from time to
time, an increase in the Aggregate Revolver Commitments by an amount for all such requests not exceeding the sum of (i) the amount of the Initial Revolver Commitment Increase Amount plus
(ii) $200,000,000; provided that any such request for an increase in the Aggregate Revolver
Commitments shall be in a minimum amount of $25,000,000; and provided further that any such increased Aggregate Revolver Commitments shall be secured
pari passu with the Obligations." 

        Paragraph 1.5    Section 5.13.    Section 5.13
of the Credit Agreement is amended by adding a new sentence at the end thereto to read in its entirety as follows:: 

"As
of the First Amendment and Increase Effective Date the Borrower will have no Subsidiaries or other equity investments other than those specifically disclosed in Amended
Schedule 5.13, all of the outstanding equity interests in such Subsidiaries and in MarkWest MWLM&R Member's membership interest in MWLM&R have been validly issued, are
fully paid and non-assessable (such representations and warranties regarding full payment and non-assessability being made only with respect to each Subsidiary that is
organized as a corporation), and the Borrower will have no equity investment in any other corporation or other entity other than those specifically disclosed in Amended
Schedule 5.13." 

        Paragraph 1.6    Article V.    Article V
of the Credit Agreement is amended by adding a new Section 5.21 thereto to read in its entirety as follows: 

        "5.21  Representations
Regarding MWLM&R. 

        (a)   As
of the First Amendment and Increase Effective Date and upon consummation of the transactions contemplated by the MWLM&R Contribution Agreement, Borrower, through the
MarkWest MWLM&R Member, will indirectly own a sixty percent (60%) membership interest in MWLM&R. 

        (b)   As
of the First Amendment and Increase Effective Date, Borrower has delivered to the Administrative Agent true and correct copies of (i) MWLM&R's Certificate of
Formation and the MWLM&R LLC Agreement, (ii) the MWLM&R Contribution Agreement and (iii) the MWLM&R Services Agreement. 

        (c)   As
of the First Amendment and Increase Effective Date, MWLM&R has no Subsidiaries." 

        Paragraph 1.7    Section 6.01.    Section 6.01
of the Credit Agreement is amended by deleting the word "and" at the end of Section 6.01(b), deleting the period at the end of Section 6.01(c) and replacing it with a semicolon followed
by the word "and" and inserting a new Section 6.01(d) to read in its entirety as follows: 

        "(d) provided, however, if MWLM&R is treated as a consolidated Subsidiary for financial reporting and accounting purposes
generally, the financial statements referred to in Sections 6.01(a) and (b) shall include MWLM&R as a consolidated Subsidiary and regardless of whether MWLM&R is treated as a
consolidated Subsidiary for financial reporting and accounting purposes generally, Borrower shall, in any case within 45 days after the end of each Fiscal Year, deliver a one year
projection/budget for MWLM&R for the year following such Fiscal Year." 

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        Paragraph
1.8    Section 6.02(f).    Section 6.02(f) of the Credit
Agreement is amended to read in its entirety as follows: 

        "(f)  promptly,
such additional information regarding the business, financial or corporate affairs of MWLM&R or any Loan Party as the Administrative Agent, at the request of
any Lender, may from time to time reasonably request, which information may include copies of any detailed audit reports, if any, management letters or recommendations submitted to the board of
directors (or the audit
committee of the board of directors) of the Borrower by independent accountants in connection with the accounts or books of the Borrower, any Subsidiary or MWLM&R, or any audit of any of them." 

        Paragraph 1.9    Section 6.03(b).    Section 6.03(b)
of the Credit Agreement is amended in its entirety to read as follows: 

        "(b) of
any matter that has resulted or could reasonably be expected to result in a Material Adverse Effect, including any of the following events if such has resulted or
could reasonably be expected to result in a Material Adverse Effect: (i) breach or non-performance of, or any default under, a Contractual Obligation of any Loan Party or of MWLM&R;
(ii) any litigation, investigation by or required by a Governmental Authority, proceeding or suspension of licenses or permits between MWLM&R or any Loan Party and any Governmental Authority;
and (iii) any dispute, litigation, investigation or proceeding involving MWLM&R or any Loan Party related to any Environmental Law;" 

        Paragraph
1.10    Section 6.03(c).    Section 6.03(c) of the Credit
Agreement is amended in its entirety to read as follows: 

        "(c) of
any litigation, investigation or proceeding known to and affecting the Borrower, any other Loan Party or MWLM&R in which (i) the amount involved exceeds
(individually or collectively) $3,500,000, or (ii) injunctive relief or other relief is sought, which could be reasonably expected to have a Material Adverse Effect; and;" 

        Paragraph
1.11    Section 6.04.    Section 6.04 of the Credit Agreement is
amended by adding a new sentence at the end thereof to read in its entirety as follows: 

"Additionally,
Borrower shall use commercially reasonable efforts to cause MWLM&R to pay and discharge as the same shall become due and payable, all of MWLM&R's obligations and liabilities, including
(a) all tax liabilities, assessments and governmental charges or levies upon MWLM&R or its properties or assets and (b) all lawful claims which, if unpaid, would by Law become a Lien
upon MWLM&R's property; except, in the case of clause (a) or (b), where (x) the validity thereof are being contested in good faith by
appropriate proceedings and (y) adequate reserves in accordance with GAAP are being maintained by MWLM&R." 

        Paragraph 1.12    Section 6.05.    Section 6.05
of the Credit Agreement is amended to read in its entirety as follows: 

        "6.05    Preservation of Existence, Etc.    (a) Preserve, renew and
maintain, and use commercially reasonable efforts to cause MWLM&R to preserve, renew and maintain, in full force and effect its legal existence and good standing under the Laws of the jurisdiction of
its organization, except in a transaction permitted by Sections 7.06 and 7.07, (b) take
all reasonable action, and use commercially reasonable efforts to cause MWLM&R to take all reasonable action, to maintain all rights, privileges, permits, licenses and franchises material to the
conduct of its business, except in a transaction permitted by Sections 7.06 and 7.07." 

8

 

        Paragraph 1.13    Section 6.06.    Section 6.06
of the Credit Agreement is amended in its entirety to read as follows: 

        "6.06    Maintenance of Assets and Business.    (a) Maintain, and use
commercially reasonable efforts to cause MWLM&R to maintain, all material properties, equipment, licenses, permits, and franchises necessary for its normal business; (b) keep, and use
commercially reasonable efforts to cause MWLM&R to keep, all of its assets which are useful in and necessary to its business in good working order and condition (ordinary wear and tear excepted) and
make all necessary repairs thereto and replacements thereof; (c) do, and use commercially reasonable efforts to cause MWLM&R to do, all things necessary to obtain, renew, extend, and continue
in effect all Authorizations which may at any time and from time to time be necessary for the operation of its business in compliance with applicable Law, except where the failure to so maintain,
renew, extend, or continue in effect could not reasonably be expected to have a Material Adverse Effect; (d) preserve or renew, and use commercially reasonable efforts to cause MWLM&R to
preserve or renew, all of its registered patents, trademarks, trade names and service marks, the non-preservation of which could reasonably be expected to have a Material Adverse Effect;
and (e) use, and use commercially reasonable efforts to cause MWLM&R to use, the standard of care typical in the industry in the operation and maintenance of its facilities." 

        Paragraph 1.14    Section 6.07(a).    Section 6.07(a)
of the Credit Agreement is amended in its entirety to read as follows: 

        "(a) Maintain,
and use commercially reasonable efforts to cause MWLM&R to maintain, with responsible insurance companies insurance with respect to its properties and
business (including business interruption insurance) against such casualties and contingencies and of such types and in such amounts as is customary in the case of similar businesses and which is
satisfactory to the Administrative Agent and the Required Lenders and will (i) furnish to the Administrative Agent on each anniversary of the Closing Date a certificate or certificates of
insurance from the applicable insurance company evidencing the existence of insurance required to be maintained by this Agreement and the other Loan Documents and evidencing that Administrative Agent
is listed as sole loss payee on property insurance and the Administrative Agent and Lenders are additional insureds on liability insurance (except that the MWLM&R insurance policies shall not be
required to list the Administrative Agent or Lenders as
sole loss payee or additional insured), and (ii) upon request of the Administrative Agent, furnish to each Lender at reasonable intervals a certificate of an Authorized Officer of the Borrower
setting forth the nature and extent of all insurance maintained in accordance with this Section." 

        Paragraph 1.15    Section 6.08.    Section 6.08
of the Credit Agreement is amended to add after the word "Comply" at the beginning of such Section the following: ", and use commercially reasonable efforts to cause MWLM&R to comply,". 

        Paragraph 1.16    Section 6.09.    Section 6.09
of the Credit Agreement is amended to add after the word "Maintain" at the beginning of such Section, the following: ", and use commercially reasonable efforts to cause MWLM&R to maintain,". 

        Paragraph 1.17    Section 6.10.    Section 6.10
of the Credit Agreement is amended to add after the word "Permit" at the beginning of such Section, the following: ", and use commercially reasonable efforts to cause MWLM&R to permit," and by adding
after the word "Subsidiaries"' in the last sentence of such Section the words "and MWLM&R's". 

        Paragraph 1.18    Section 6.12(b)(iii).    Section 6.12(b)(iii)
of the Credit Agreement is amended in its entirety to read as follows: 

        "(iii)  finance
working capital requirements and other general corporate purposes of the Borrower, its Subsidiaries and MWLM&R;" 

9

 

        Paragraph 1.19    Section 6.14.    Section 6.14
of the Credit Agreement is amended by adding a new sentence at the end thereof to read as follows: 

        "If
and when Borrower or its Subsidiaries own, directly or indirectly, 100% of the membership interest in MWLM&R, Borrower shall cause MWLM&R to comply with the provisions of
clauses (a) and (b) of this Section; provided, however, unless a Default or Event of Default then exists, whenever Borrower's or any of its Subsidiaries ownership interest falls to 90%
or less, the guarantee and pledge of assets by MWLM&R shall automatically terminate and be released." 

        Paragraph 1.20    Section 6.15(b).    Section 6.15(b)
of the Credit Agreement is amended by adding a new sentence at the end thereof to read as follows: 

        "Additionally,
Borrower shall cause MWLM&R to execute an acknowledgment of the pledge by the MarkWest MWLM&R Member of its Class B Interest in MWLM&R to the Administrative Agent
and Collateral Agent, on behalf of the Secured Parties, and shall pledge or cause the MarkWest MWLM&R Member and any other Subsidiary of the Borrower that owns or acquires any additional membership
interest in MWLM&R to pledge such additional membership interests in MWLM&R to the Administrative Agent and Collateral Agent, on behalf of the Secured Parties." 

        Paragraph 1.21    Section 7.02.    Section 7.02
of the Credit Agreement is amended by deleting the word "and" at the end of Section 7.02(f), deleting the period at the end of  Section 7.02(g)
 and substituting a semicolon therefor and adding the word "and" at the end thereof and adding a new  Section 7.02(h) to read in its entirety as follows:
 

        "(h) Investments
in MWLM&R consisting of (i) the initial contribution of approximately $100,000,000 of assets by the MarkWest MWLM&R Member and (ii) subsequent
capital contributions (A) on an as needed basis to achieve and maintain the MarkWest MWLM&R Member's 60% investment balance in MWLM&R and (B) other capital contributions that increase
the percentage of MarkWest MWLM&R Member's investment balance in MWLM&R." 

        Paragraph 1.22    Section 7.15(c).    Section 7.15(c)
of the Credit Agreement is amended in its entirety to read as follows: 

        "(c)    Senior Leverage Ratio.    Permit the Senior Leverage Ratio at any fiscal
quarter-end to be greater than 3.0 to 1.0 unless such quarter-end occurs during any Acquisition Adjustment Period, in which case
the Senior Leverage Ratio cannot be greater than 3.5 to 1.0." 

        Paragraph 1.23    Section 7.15(e).    Section 7.15(e)
of the Credit Agreement is amended in its entirety to read as follows: 

        "(e)    Adjustments for Material Projects.    For purposes of determining compliance with  Sections 7.15(a), (b) and (c)
 in the event the Borrower or any of its consolidated Subsidiaries (or MWLM&R) undertakes a Material Project,
a Material Project Consolidated EBITDA Adjustment may be made at Borrower's option. As used herein a "Material Project Consolidated EBITDA Adjustment"
means, with respect to each Material Project: 

          (i)  prior
to the Commercial Operation Date of a Material Project (but including the fiscal quarter in which such Commercial Operation Date occurs), a percentage (equal to
the then-current completion percentage of such Material Project) of an amount to be approved by the Administrative Agent as the projected Consolidated EBITDA of the Borrower (or in the
case of MWLM&R, projected distributions of MWLM&R Available Cash to the MarkWest MWLM&R Member) attributable to such Material Project for the first 12-month period following the scheduled
Commercial Operation Date of such Material Project (such amount to be determined based on contracts relating to such Material Project, the creditworthiness of the other parties to such contracts, and
projected revenues from such contracts, capital costs and 

10

 

expenses,
scheduled Commercial Operation Date, and other factors reasonably deemed appropriate by the Administrative Agent, including, in the case of MWLM&R, the ownership percentage of the MarkWest
MWLM&R Member), which may, at the Borrower's option, be added to actual Consolidated EBITDA for the fiscal quarter in which construction of such Material Project commences and for each fiscal quarter
thereafter until the Commercial Operation Date of such Material Project (including the fiscal quarter in which such Commercial Operation Date occurs, but net of any actual Consolidated EBITDA of the
Borrower (or in the case of MWLM&R, any actual distributions of Available Cash distributed to the MarkWest MWLM&R Member) attributable to such Material Project following such Commercial Operation
Date); provided that if the actual Commercial Operation Date does not occur by the scheduled Commercial Operation Date, then the foregoing amount shall
be reduced, for quarters ending after the scheduled Commercial Operation Date to (but excluding) the first full quarter after its actual Commercial Operation Date, by the following percentage amounts
depending on the period of delay (based on the period of actual delay or then-estimated delay, whichever is longer): (i) 90 days or less, 0%, (ii) longer than
90 days, but not more than 180 days, 25%, (iii) longer than 180 days but not more than 270 days, 50%, and (iv) longer than 270 days, 100%; and 

         (ii)  beginning
with the first full fiscal quarter following the Commercial Operation Date of a Material Project and for the two immediately succeeding fiscal quarters, an
amount to be approved by the Administrative Agent as the projected Consolidated EBITDA of the Borrower (or in the case of MWLM&R, projected distributions of MWLM&R Available Cash to the MarkWest
MWLM&R Member) attributable to such Material Project (determined in the same manner as set forth in clause (i) above) for the balance of the four full fiscal quarter period following such
Commercial Operation Date, which may, at Borrower's option, be added to actual Consolidated EBITDA for such fiscal quarters (but net of any actual Consolidated EBITDA of the Borrower (or in the case
of MWLM&R, net of any actual distributions of Available Cash distributed to the MarkWest MWLM&R Member) attributable to such Material Project following such Commercial Operation Date). 

        (iii)  Notwithstanding
the foregoing: (A) no such additions shall be allowed with respect to any Material Project unless: (y) not later than 30 days
prior to the delivery of any Compliance Certificate required by the terms and provisions of Section 6.02(a) to the extent Material Project
Consolidated EBITDA Adjustments will be made to Adjusted Consolidated EBITDA in determining compliance with this Section 7.15, the Borrower shall
have delivered to the Administrative Agent written pro forma projections of Consolidated EBITDA of the Borrower (or its consolidated Subsidiary) attributable to such Material Project (or in the case
of MWLM&R, projected distributions of Available Cash to be distributed to the MarkWest MWLM&R Member attributable to such Material Project), and (z) prior to the date such Compliance
Certificate is required to be delivered, the Administrative Agent shall have
approved (such approval not to be unreasonably withheld, conditioned or delayed) such projections and shall have received such other information and documentation as the Administrative Agent may
reasonably request, all in form and substance reasonably satisfactory to the Administrative Agent, and (B) the aggregate amount of all Material Project Consolidated EBITDA Adjustments during
any period shall be limited to 15% of the total actual Consolidated EBITDA of the Borrower and its consolidated Subsidiaries for such period and cash dividends or cash distributions actually received
by the Borrower and its Subsidiaries from MWLM&R for such period (which total actual Consolidated EBITDA shall be determined without including any Material Project Consolidated EBITDA Adjustments)." 

11

 

        Paragraph 1.24    Article VII.    Article VII
of the Credit Agreement is amended by adding a new Section 7.16 thereto to read in its entirety as follows: 

        "7.16    Negative Covenants Pertaining to MWLM&R.    The Borrower
agrees that it shall use commercially reasonable efforts to not permit MWLM&R to, directly or indirectly: 

        (a)   create,
incur, or assume any Indebtedness except: 

          (i)  Indebtedness
(contingent or otherwise) of MWLM&R existing or arising under any Swap Contract to the extent permitted by  Section 7.16(c); 

         (ii)  Indebtedness
of MWLM&R in respect of purchase money obligations for fixed or capital assets; 

        (iii)  Indebtedness
of MWLM&R not to exceed $10,000,000 which may be secured or unsecured. 

        (b)   create,
incur, assume or suffer to exist any Lien upon any of its property, assets or revenues, whether now owned or hereafter acquired, other than the following: 

          (i)  Liens
securing Indebtedness permitted pursuant to Sections 7.16(a)(i),  (ii) and (iii);
provided in the case of  Section 7.16(a)(ii) such Liens do not extend to cover property other than the property being acquired; 

         (ii)  Liens
described in Section 7.01(c), (d), (e) and (f); 

        (iii)  easements,
rights-of-way, restrictions and other encumbrances affecting real property; 

        (iv)  judgment
Liens; 

         (v)  any
Lien existing on any asset prior to acquisition thereof by MWLM&R so long as any such Lien encumbers only such asset after its acquisition; 

        (vi)  Liens
reserved in or exercisable under any lease or sublease to which MWLM&R is a lessee which secure the payment of rent or compliance with the terms of such lease or
sublease; 

       (vii)  any
interest or title of a lessor under any lease entered into by MWLM&R in the ordinary course of its business and covering only the assets so leased; and 

      (viii)  a
Lien in favor of the NGP MWLM&R Member on the "escrow account" (as defined in the MWLM&R LLC Agreement). 

        (c)   enter
into any Swap Contracts other than in the ordinary course of business for the purpose of protecting against fluctuations in interest rates, commodity prices, or
foreign exchange rates and not for purposes of speculation; 

        (d)   consummate
any Asset Sale (as defined in any Senior Note Indenture) in breach of the provisions of any Senior Note Indenture (as the same may be amended, waived or
modified from time to time); 

        (e)   alter,
or permit the MarkWest MWLM&R Member to alter, the provisions of the MWLM&R LLC Agreement providing for distributions of MWLM&R Available Cash (or change
any of the definitions used in or otherwise applicable to such provisions) within 45 days following the end of each calendar quarter as follows: 

          (i)  following
the end of each calendar quarter on or prior to the earlier to occur of (A) the calendar quarter ending December 31, 2010 and (B) the
"equalization date" (as defined in the MWLM&R LLC Agreement), MWLM&R Available Cash will be retained by MWLM&R for reinvestment, and with respect to the Class B Member (which initially
includes 

12

 

only
the MarkWest MWLM&R Member) such MWLM&R Available Cash will be distributed and automatically reinvested as additional capital contributions; 

         (ii)  following
the end of each calendar quarter on or after the earlier to occur of (A) the calendar quarter ending December 31, 2010, and (B) the
"equalization date" (as defined in the MWLM&R LLC Agreement), MWLM&R Available Cash will be distributed first to the Class A Member (which initially includes only the NGP MWLM&R Member)
until the preferred return accruing that quarter on its overfunded capital amount is reduced to zero and thereafter will be distributed to the MWLM&R "members" (as defined in the MWLM&R LLC
Agreement) in accordance with their respective "percentage interests" (as defined in the MWLM&R LLC Agreement); and 

        (iii)  after
"equalization" (as defined in the MWLM&R LLC Agreement) is achieved, MWLM&R Available Cash will be distributed to the MWLM&R "members" (as defined in the
MWLM&R LLC Agreement) in accordance with their respective "percentage interests" (as defined in the MWLM&R LLC Agreement). 

        (f)    engage
in any Affiliate Transaction (as defined in any Senior Note Indenture) in breach of the provisions of any Senior Note Indenture (as the same may be amended,
waived or modified from time to time); 

        (g)   engage
in any sale and leaseback transaction in breach of the provisions of any Senior Note Indenture (as the same may be amended, waived or modified from time to time); 

        (h)   engage
in any line of business other than the Midstream Business or make any Capital Expenditures except in connection with the Midstream Business; 

        (i)    enter
into any Contractual Obligation (other than the MWLM&R LLC Agreement) or permit any amendment to the MWLM&R LLC Agreement that would (i) have
the effect of reducing distributions of MWLM&R Available Cash to the MarkWest MWLM&R Member to an amount less than its investment balance in MWLM&R or (ii) change the characterization of the
membership interest in MWLM&R as a "security" or "general intangible" (as those terms are defined in the Texas Uniform Commercial Code) from that existing on the First Amendment and Increase Effective
Date." 

        Paragraph 1.25    Section 8.01.    Section 8.01
of the Credit Agreement is amended by deleting the word "or" at the end of Section 8.01(m), deleting the period at the end of Section 8.01(n) and substituting therefor a semicolon and
adding the word "or" at the end thereof and adding a new Section 8.01(o) to read in its entirety as follows: 

        "(o)    MWLM&R Insolvency Proceedings, Etc.    (i) MWLM&R institutes or consents
to the institution of any proceeding under any Debtor Relief Law, or makes an assignment for the benefit of creditors; or applies for or consents to the appointment of any receiver, trustee,
custodian, conservator, liquidator, rehabilitator or similar officer for it or for all or any material part of its property or takes any action to effect any of the foregoing; or (ii) any
receiver, trustee, custodian, conservator, liquidator, rehabilitator or similar officer is appointed without the application or consent of MWLM&R and the appointment continues undischarged or unstayed
for 60 calendar days; or (iii) any proceeding under any Debtor Relief Law relating to MWLM&R or to all or any part of its property is instituted without the consent of MWLM&R and continues
undismissed or unstayed for 60 calendar days, or an order for relief is entered in any such proceeding." 

        Paragraph 1.26    Amended
Schedule 2.01.    Schedule 2.01 to the Credit Agreement is hereby amended in its entirety
by Amended Schedule 2.01 "Aggregate Commitments" attached to this Amendment. Any reference in the Credit Agreement to such Schedule shall be deemed to refer to such
Schedule as amended by Amended Schedule 2.01. 

13

 

        Paragraph 1.27    Amended
Schedule 5.13.    Schedule 5.13 to the Credit Agreement is hereby amended by
Amended Schedule 5.13 "Subsidiaries and Other Equity Investment" attached to this Amendment. Any reference in the Credit Agreement to such Schedule shall be deemed
to refer to such Schedule as amended by Amended Schedule 5.13. 

        Paragraph 1.28    Amendment to
Schedule 7.04    Schedule 7.04 to the Credit Agreement is hereby amended in its entirety
by Amended Schedule 7.04 "Existing Indebtedness" attached to this Amendment. Any reference in the Credit Agreement to such Schedule shall be deemed to refer to such Schedule as amended by
Amended Schedule 7.04. 

        Paragraph 1.29    Supplements to
Exhibits.    Exhibit A-1 "Borrowing Notice" and  Exhibit C "Compliance
Certificate" to the Credit Agreement are hereby supplemented with Supplemental
Exhibit A-1 "Borrowing Notice" and Supplemental Exhibit C "Compliance Certificate" attached to this Amendment. Any reference in
the Credit Agreement to such Exhibits shall be deemed
to refer to such Exhibits as supplemented by Supplemental Exhibit A-1 and Supplemental Exhibit C. 

        Paragraph 1.30    Acknowledgment of Repayment of Term
Loans.    Borrower, Guarantors and Lenders acknowledge that the Term Loans have been repaid. The Term Loan Commitment has been reduced to zero and
cancelled and no amount of Term Loans may be reborrowed. References in the Credit Agreement to "Term Lender," "Term Loan Commitment," "Term Loan Facility," "Term Loan Principal Debt," "Term Loan Pro
Rata Share," "Term Loans" and "Term Note" have no force or effect and shall be disregarded for all purposes. 

        Paragraph 1.31    Release of Lien on Collateral Contributed to
MWLM&R.    The Administrative Agent and/or Collateral Agent is authorized to release the Liens securing the Obligations on the Collateral described on
the Annexes to this Amendment (the "Released Property") which Collateral is being contributed to MWLM&R by the MarkWest MWLM&R Member pursuant to the
MWLM&R Contribution Agreement. The Administrative Agent and Collateral Agent hereby agree that immediately upon consummation of the transactions contemplated by the MWLM&R Contribution Agreement, the
Administrative Agent's and Collateral Agent's security interests in, security titles to and other Liens on the Released Property will be automatically terminated and released, and the Administrative
Agent and/or Collateral Agent will execute any and all other lien release documents in form and substance reasonably acceptable to the Administrative Agent and the Collateral Agent as Borrower may
deem necessary or appropriate in order to evidence or otherwise give public notice of such collateral terminations and releases (provided,
however, that any and all such releases and other such documents must be prepared and recorded at Borrower's expense) and thereafter the Administrative Agent and
Collateral Agent will not seek to enforce any lien or other interest in the Released Property against any new owner. 

14

 

 
        Paragraph 2.    Revolver Commitment
Increase.    

        (a)   The
Borrower and the parties signatory to this Amendment as Increasing Lenders and New Lender hereby agree that, from and after the First Amendment and Increase
Effective Date, the Increasing Lenders and New Lender shall have the respective Revolver Commitments as set forth as follows: 

												
	Increasing Lender or New

Lender

 
	 	Existing Revolver

Commitment 	 	Revolver Commitment

Increase 	 	New Revolver

Commitment 	 
	 Royal Bank of Canada
	 	$	23,130,434.79	 	$	20,000,000.00	 	$	43,130,434.79	 
	 JPMorgan Chase Bank, N.A. 
	 	$	18,869,565.22	 	$	4,600,000.00	 	$	23,469,565.22	 
	 U.S. Bank National Association
	 	$	18,869,565.22	 	$	15,000,000.00	 	$	33,869,565.22	 
	 Deutsche Bank Trust Company Americas
	 	$	15,217,391.30	 	$	10,000,000.00	 	$	25,217,391.30	 
	 Compass Bank
	 	$	18,869,565.22	 	$	5,000,000.00	 	$	23,869,565.22	 
	 Wachovia Bank, National Association
	 	$	18,869,565.22	 	$	5,000,000.00	 	$	23,869,565.22	 
	 Morgan Stanley Bank
	 	$	9,130,434.78	 	$	6,000,000.00	 	$	15,130,434.78	 
	 Barclays Bank PLC
	 	$	0.00	 	$	20,000,000.00	 	$	20,000,000.00	 
	 	 TOTAL:
	 	 	 	 	$	85,600,000.00	 	 	 	 

Such
increase in the Revolver Commitments of the Increasing Lenders and new Revolver Commitment of the New Lender shall represent an increase in the Aggregate Revolver Commitments pursuant to  Section 2.15(a)
 of the Credit Agreement. 

        (b)   Administrative
Agent and Borrower hereby consent to and approve the increase in the Revolver Commitment of each Increasing Lender and the new Revolver Commitment of the
New Lender, and such resulting increase in the Aggregate Revolver Commitments pursuant to Section 2.15(a) of the Credit Agreement. 

        (c)   Each
Increasing Lender and New Lender hereby represents and warrants to the Administrative Agent and L/C Issuer as follows: (a) it has full power and authority,
and has taken all action necessary, to execute and deliver this Amendment, to consummate the transactions contemplated hereby and to continue to be (or become, in the case of a New Lender) a Lender
under the Credit Agreement, and (b) from and after the First Amendment and Increase Effective Date, it shall be bound by the provisions of the Credit Agreement as a Lender thereunder and, to
the extent of its increased Revolver Commitment, shall have the obligations of a Lender thereunder. The New Lender shall be entitled to the benefits afforded to Lenders under the Credit Agreement and
the other Loan Documents, including without limitation the benefits of Sections 3.07, 10.04 and  10.05. This Amendment shall serve as a joinder agreement for the New Lender to become a Revolver Lender and Administrative Agent acknowledges and agrees
that this Amendment is in form and substance satisfactory to it for such purpose. 

        (d)   The
increase in the Aggregate Revolver Commitment shall be effective on the First Amendment and Increase Effective Date. 

        (e)   Notwithstanding
that the Revolver Commitment Increase Amount is being effected by means of this Amendment, this is for convenience of the Borrower, Administrative Agent
and Increasing Lenders only and no other Lender's approval or consent is necessary or required and Required Lender approval or consent is also not required to increase the Aggregate Revolver
Commitments by the Revolver Commitment Increase Amount. 

        Paragraph 3.    Waiver.    

        (a)   The
Borrower has requested that the Lenders waive the requirement of Section 6.14 of the Credit Agreement insofar
as it would otherwise require MWLM&R to execute a Guaranty and Collateral Documents to guarantee and secure the Indebtedness within 30 days of MWLM&R's 

15

 

formation,
to permit Borrower to form MWLM&R more than 30 days prior to the First Amendment and Increase Effective Date. The foregoing waiver shall cease to be of any force or effect on and
after April 1, 2009, if the First Amendment and Increase Effective Date does not occur on or before March 31, 2009. 

        (b)   The
foregoing waiver shall not be deemed to be a waiver by the Lenders of any other covenant, condition or obligation on the part of the Borrower under the Credit
Agreement or any other Loan Document, except as set forth in Paragraph 3 of this Amendment. In addition, the foregoing waiver shall in no respect
evidence any commitment by the Lenders to grant any future consents or waivers of any covenant, condition or obligation on the part of the Borrower under the Credit Agreement or any other Loan
Document. Any further waivers or consents must be specifically agreed to in writing in accordance with Section 10.01 of the Credit Agreement. 

        (c)   NOTWITHSTANDING THAT THE AMENDMENTS EFFECTED BY THIS AMENDMENT AND THE INCREASE IN THE REVOLVER COMMITMENT SHALL NOT BE EFFECTIVE UNTIL THE
OCCURRENCE OF THE FIRST AMENDMENT AND INCREASE EFFECTIVE DATE, THE FOREGOING WAIVER IS EFFECTIVE FOR ALL PURPOSES UPON THE OCCURRENCE OF THE FIRST AMENDMENT SIGNING DATE PROVIDED REQUIRED LENDERS HAVE
CONSENTED THERETO, WHICH CONSENT SHALL BE EVIDENCED BY A LENDER'S EXECUTION OF ITS SIGNATURE PAGE ATTACHED TO THIS AMENDMENT.

        Paragraph 4.    First Amendment and Increase Effective
Date.    This Amendment shall not become effective (other than as set forth in Paragraph 3 with
respect to the waiver set forth therein) until the date (such date, the "First Amendment and Increase Effective Date") the Administrative Agent receives
all of the agreements, documents, certificates, instruments, and other items described below: 

        (a)   this
Amendment, executed by the Borrower, the Guarantors, the Required Lenders, each Increasing Lender, each New Lender, the Administrative Agent and the L/C Issuer; 

        (b)   replacement
Revolver Notes for the Increasing Lenders and a new Revolver Note for the New Lender executed by the Borrower in favor of each such Lender requesting such
Notes, each Revolver Note in a principal amount equal to such Revolver Lender's Revolver Commitment and each Revolver Note dated as of the First Amendment and Increase Effective Date; 

        (c)   amendments
or supplements to Mortgages that have been requested by the Administrative Agent or its counsel prior to the First Amendment Signing Date; 

        (d)   an
amendment to the Security Agreement from the MarkWest MWLM&R Member evidencing the pledge of its membership interest in MWLM&R; 

        (e)   an
acknowledgment from MWLM&R of the pledge by MarkWest MWLM&R of its membership interest in MWLM&R; 

        (f)    from
the Borrower and the Guarantors, such certificates of secretary, assistant secretary, manager, or general partner, as applicable, as the Administrative Agent may
require, certifying (i) resolutions of its board of directors, managers or members (or their equivalent) authorizing the execution and performance of this Amendment which such Person is
executing in connection herewith, (ii) the incumbency and signature of the officer executing this Amendment, and (iii) there has been no change in such Person's Organization Documents
from the copies of such Person's Organization Documents most recently delivered to the Administrative Agent and Lenders or attaching any amendments or restatements thereof; 

        (g)   a
certificate from Borrower (i) representing and warranting that, on and as of the First Amendment and Increase Effective Date, before and after giving effect to
the increase in Aggregate Revolver Commitments resulting hereunder (A) no Default or Event of Default exists or would exist immediately after giving effect to the increase in the Aggregate
Revolver Commitments, (B) the representations and warranties contained in Article V and the other Loan Documents are true and 

16

 

correct
in all material respects on and as of the First Amendment and Increase Effective Date, except to the extent that such representations and warranties specifically refer to an earlier date, in
which case they are true and correct in all material respects as of such earlier date, and except that the representations and warranties contained in  subsections (a) and (b) of Section 5.05
shall be deemed to refer to the most recent financial statements furnished pursuant to clauses (a) and  (b), respectively, of
Section 6.01, and (C) all financial covenants in
Section 7.15 would be satisfied on a pro forma basis as of the most recent testing date and on the First Amendment and Increase Effective Date
after giving effect to actual Credit Extensions on the First Amendment and Increase Effective Date, if any, (ii) ratifying and confirming each of the Loan Documents, (iii) agreeing that
all Loan Documents shall apply to the Obligations as they are or may be increased by this Amendment, (iv) agreeing that its obligations and covenants under each Loan Document are otherwise
unimpaired by this Amendment and shall remain in full force and effect, and (iv) certifying, pursuant to Section 7.07(c) of the Agreement
that the Disposition of assets by the MarkWest MWLM&R Member to the Joint Venture will be for fair market value. 

        (h)   payment
on the First Amendment and Increase Effective Date to the Administrative Agent of an amendment and waiver fee equal to fifty (50) basis points on the
amount of the Aggregate Revolver Commitments of all approving Lenders (without giving effect to any Revolver Commitment Increase Amount), which amendment and waiver fee will be paid to each Lender
(based on each such Lender's Aggregate Revolver Commitment without giving effect to any Revolver Commitment Increase Amount) that sends a signed consent form to the Administrative Agent by
5:00 p.m. New York time on January 26, 2009 and a signed signature page to this Amendment to the Administrative Agent's counsel by noon, New York time on January 28, 2009, which
fee once paid will be fully earned and nonrefundable; 

        (i)    payment
on the First Amendment and Increase Effective Date to the Administrative Agent of a commitment increase fee of two hundred (200) basis points, calculated
on the Initial Revolver Commitment Increase Amount, which fee will be shared among each Increasing Lender and New Lender that sends a signed commitment letter to the Administrative Agent by
5:00 p.m. New York time on January 26, 2009 and a signed signature page to this Amendment to the Administrative Agent's counsel by noon, New York time on January 28, 2009, which
fee will be shared among the Increasing Lenders and New Lender in accordance with their respective pro rata share of the Initial Revolver Commitment Increase Amount, which fee once paid will be fully
earned and nonrefundable; 

        (j)    fees
and expenses required to be paid pursuant to Paragraph 7 of this Amendment, to the extent invoiced prior to
the First Amendment and Increase Effective Date; 

        (k)   evidence
satisfactory to the Administrative Agent that any necessary consents to the transactions contemplated in this Amendment from the holders of the Senior Unsecured
Notes have been obtained and are in full force and effect; 

        (l)    a
certificate of a Responsible Officer of Borrower certifying that (1) MWLM&R has been formed, (2) the transactions contemplated by the MWLM&R Contribution
Agreement have been consummated, and (3) the NGP MWLM&R Member has been admitted as a member of MWLM&R and attaching true and correct copies of the Organization Documents of MWLM&R (including
its Certificate of Formation and the MWLM&R LLC Agreement), the MWLM&R Contribution Agreement and the MWLM&R Services Agreement; 

        (m)  an
opinion from Hogan & Hartson, L.L.P., counsel to each Loan Party and the General Partner, in form and substance satisfactory to the Administrative Agent
and its counsel (it being understood and agreed that the form and substance of the draft opinion delivered to the Administrative Agent and its counsel on the First Amendment Signing Date is
satisfactory); and 

17

 

        (n)   such
other assurances, certificates, documents and consents as the Administrative Agent may request prior to the First Amendment Signing Date. 

        Paragraph 5.    Acknowledgment and
Ratification.    As a material inducement to the Administrative Agent and the Lenders to execute and deliver this Amendment, each of the Borrower and
the Guarantors (i) consents to the agreements in this Amendment, (ii) agrees and acknowledges that the execution, delivery, and performance of this Amendment shall in no way release,
diminish, impair, reduce, or
otherwise affect the respective obligations of the Borrower or any Guarantor under the Loan Documents to which it is a party, which Loan Documents shall remain in full force and effect, and all rights
thereunder are hereby ratified and confirmed. 

        Paragraph 6.    Representations.    As
a material inducement to the Administrative Agent and the Lenders to execute and deliver this Amendment, each of the Borrower and the Guarantors represents and warrants to the Administrative Agent and
the Lenders that as of the First Amendment and Increase Effective Date and as of the date of execution of this Amendment, (a) all representations and warranties in the Loan Documents are true
and correct in all material respects as though made on the date hereof, except to the extent that any of them speak to a different specific date (in which case such representations and warranties
shall be true and correct in all material respect as of such specific date), and (b) no Default or Event of Default exists. 

        Paragraph 7.    Expenses, Funding
Losses.    The Borrower shall pay on demand all reasonable costs, fees, and expenses paid or incurred by the Administrative Agent incident to this
Amendment, including, without limitation, Attorney Costs in connection with the negotiation, preparation, delivery, and execution of this Amendment and any related documents, filing and recording
costs, and the costs of title insurance endorsements, if any. 

        Paragraph 8.    Miscellaneous.    

        (a)   This
Amendment is a "Loan Document" referred to in the Credit Agreement. The provisions relating to Loan Documents in  Article X of the Credit Agreement are incorporated in this Amendment by
reference. Unless stated otherwise (a) the singular number
includes the plural and vice versa and words of any gender include each other gender, in each case, as appropriate, (b) headings and captions may not be construed in interpreting provisions,
(c) this Amendment must be construed, and its performance enforced, under Texas law and applicable federal law, (d) if any part of this Amendment is for any reason found to be
unenforceable, all other portions of it nevertheless remain enforceable, and (e) this Amendment may be executed in any number of counterparts with the same effect as if all signatories had
signed the same document, and all of those counterparts must be construed together to constitute the same document. 

        Paragraph 9.    ENTIRE
AGREEMENT.    THIS AMENDMENT REPRESENTS THE FINAL AGREEMENT BETWEEN THE PARTIES ABOUT THE SUBJECT MATTER OF THIS AMENDMENT AND
MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

        Paragraph 10.    Parties.    This
Amendment binds and inures to the benefit of the Borrower, the Guarantors, the Administrative Agent, the Collateral Agent, the other Lenders, and their respective successors and assigns. 

        Paragraph 11.    Further
Assurances.    The parties hereto each agree to execute from time to time such further documents as may be necessary to implement the terms of this
Amendment. 

        Paragraph 12.    Release.    As
additional consideration for the execution, delivery and performance of this Amendment by the parties hereto and to induce the Administrative Agent, the Collateral Agent, the other Agents and the
Lenders to enter into this Amendment, the Borrower warrants and represents to the Administrative Agent, the Collateral Agent, the other Agents and the Lenders that to the best of 

18

 

its
knowledge no facts, events, statuses or conditions exist or have existed which, either now or with the passage of time or giving of notice, or both, constitute or will constitute a basis for any
claim or cause of action against the Administrative Agent, the Collateral Agent, any other Agent or any Lender or any defense to (i) the payment of Obligations under the Revolver Notes and/or
the Loan Documents, or (ii) the performance of any of its obligations with respect to the Revolver Notes and/or the Loan Documents. In the event any such facts, events, statuses or conditions
exist or have existed, Borrower unconditionally and irrevocably hereby RELEASES, RELINQUISHES and forever DISCHARGES Administrative Agent, the Collateral Agent, the other Agents and the Lenders, as
well as their predecessors, successors, assigns, agents, officers, directors, shareholders, employees and representatives, of and from any and all claims, demands, actions and causes of action of any
and every kind or character, past or present, which Borrower may have against any of them or their predecessors, successors, assigns, agents, officers, directors, shareholders, employees and
representatives arising out of or with respect to (a) any right or power to bring any claim for usury or to pursue any cause of action based on any claim of usury, and (b) any and all
transactions relating to the Loan Documents occurring prior to the date hereof, including any loss, cost or damage, of any kind or character, arising out of or in any way connected with or in any way
resulting from the acts, actions or omissions of any of them, and their predecessors, successors, assigns, agents, officers, directors, shareholders, employees and representatives, including any
breach of fiduciary duty, breach of any duty of fair dealing, breach of confidence, breach of funding commitment, undue influence, duress, economic coercion, conflict of interest, negligence, bad
faith, malpractice, intentional or negligent infliction of mental distress, tortious interference with contractual relations, tortious interference with corporate governance or prospective business
advantage, breach of contract, deceptive trade practices, libel, slander or conspiracy, but in each case only to the extent permitted by applicable Law. 

        The
parties hereto have executed this Amendment in multiple counterparts to be effective as of the First Amendment and Increase Effective Date. 

Remainder of Page Intentionally Blank

Signature Pages to Follow.  

19

 

 
        IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be duly executed as of the date first above written. 

									
	 	 	BORROWER:	 	MARKWEST ENERGY PARTNERS, L.P.,

a Delaware limited partnership,
	

 	
 	
By:	
 	
MarkWest Energy GP, L.L.C.,

its General Partner
	

 	
 	
 	
 	
By:	
 	
/s/ Andrew L. Schroeder

  Andrew L. Schroeder

Vice President and Treasurer

Signature Page 1

 

							
	 	 	GUARANTORS:	 	MARKWEST ENERGY GP, L.L.C,

a Delaware limited liability company
	

 	
 	
By:	
 	
/s/ Andrew L. Schroeder

  Andrew L. Schroeder

Vice President and Treasurer
	

 	
 	
MARKWEST ENERGY FINANCE CORPORATION
	

 	
 	
By:	
 	
/s/ Andrew L. Schroeder

  Andrew L. Schroeder

Vice President and Treasurer
	

 	
 	
MARKWEST ENERGY OPERATING COMPANY, L.L.C.
	

 	
 	
By:	
 	
MarkWest Energy Partners, L.P.

its Managing Member
	

 	
 	
By:	
 	
MarkWest Energy GP, L.L.C.,

its General Partner
	

 	
 	
By:	
 	
/s/ Andrew L. Schroeder

  Andrew L. Schroeder

Vice President and Treasurer
	

 	
 	
MARKWEST HYDROCARBON, INC.
	

 	
 	
By:	
 	
/s/ Andrew L. Schroeder

  Andrew L. Schroeder

Vice President and Treasurer

Signature Page 2

 

							
	 	 	BASIN PIPELINE, L.L.C.,

MASON PIPELINE LIMITED LIABILITY COMPANY

WEST SHORE PROCESSING COMPANY, L.L.C.,

MARKWEST ENERGY APPALACHIA, L.L.C.,

MARKWEST MICHIGAN PIPELINE COMPANY, L.L.C.,

MARKWEST OKLAHOMA GAS COMPANY, L.L.C.,

MARKWEST PIONEER, L.L.C.,

MARKWEST GAS SERVICES, L.L.C.,

MARKWEST POWER TEX, L.L.C.,

MARKWEST PINNACLE, L.L.C.,

MARKWEST PNG UTILITY, L.L.C.,

MARKWEST TEXAS PNG UTILITY, L.L.C.,

MARKWEST BLACKHAWK, L.L.C.,

MARKWEST NEW MEXICO, L.L.C.,

MARKWEST ENERGY EAST TEXAS GAS COMPANY, L.L.C.,

MARKWEST PIPELINE COMPANY, L.L.C.,

MARKWEST JAVELINA COMPANY, L.L.C,

MARKWEST JAVELINA PIPELINE COMPANY, L.L.C.

MARKWEST LIBERTY GAS GATHERING, LLC

MARKWEST MARKETING, L.L.C.

MARKWEST GAS MARKETING, L.L.C.
	

 	
 	
By:	
 	
MarkWest Energy Operating Company, L.L.C.,

its sole Member
	

 	
 	
By:	
 	
MarkWest Energy Partners, L.P.

its Managing Member
	

 	
 	
By:	
 	
MarkWest Energy GP, L.L.C.,

its General Partner
	

 	
 	
 	
 	
By:	
 	
/s/ Andrew L. Schroeder

  Andrew L. Schroeder

Vice President and Treasurer

Signature Page 3

 

							
	 	 	MATREX L.L.C.
	

 	
 	
By:	
 	
Basin Pipeline, L.L.C.,

its sole Member
	

 	
 	
By:	
 	
MarkWest Texas GP, L.L.C.

its sole Member
	

 	
 	
By:	
 	
MarkWest Energy Operating Company, L.L.C.,

its sole Member
	

 	
 	
By:	
 	
MarkWest Energy Partners, L.P.

its Managing Member
	

 	
 	
By:	
 	
MarkWest Energy GP, L.L.C.,

its General Partner
	

 	
 	
By:	
 	
/s/ Andrew L. Schroeder

  Andrew L. Schroeder

Vice President and Treasurer
	

 	
 	
MARKWEST McALESTER, L.L.C.
	

 	
 	
By:	
 	
MarkWest Oklahoma Gas Company, L.L.C.

its sole Member
	

 	
 	
By:	
 	
MarkWest Energy Operating Company, L.L.C.,

its sole Member
	

 	
 	
By:	
 	
MarkWest Energy Partners, L.P.

its Managing Member
	

 	
 	
By:	
 	
MarkWest Energy GP, L.L.C.,

its General Partner
	

 	
 	
 	
 	
By:	
 	
/s/ Andrew L. Schroeder

  Andrew L. Schroeder

Vice President and Treasurer

Signature Page 4

 

					
	AGENTS AND LENDERS:	 	ROYAL BANK OF CANADA,

as Administrative Agent and Collateral Agent
	

 	
 	
By:	
 	
/s/ Renuka Gnanaswaran

 
	 	 	Name:	 	Renuka Gnanaswaran
	 	 	Title:	 	Manager, Agency

Signature Page 5

 

					
	 	 	ROYAL BANK OF CANADA,

as L/C Issuer, Lender and Increasing Lender
	

 	
 	
By:	
 	
/s/ Jason S. York

 
	 	 	Name:	 	Jason S. York
	 	 	Title:	 	Authorized Signatory

Signature Page 6

 

					
	 	 	JPMORGAN CHASE BANK, N.A.,

as Co-Syndication Agent, Lender and Increasing Lender
	

 	
 	
By:	
 	
/s/ Stephanie Casas

 
	 	 	Name:	 	Stephanie Casas
	 	 	Title:	 	Vice President

Signature Page 7

 

					
	 	 	WACHOVIA BANK, NATIONAL ASSOCIATION,

as Co-Syndication Agent, Lender and Increasing Lender
	

 	
 	
By:	
 	
/s/ Leanne S. Phillips

 
	 	 	Name:	 	Leanne S. Phillips
	 	 	Title:	 	Director

Signature Page 8

 

					
	 	 	FORTIS CAPITAL CORP.,

as Co-Documentation Agent and Lender
	

 	
 	
By:	
 	
/s/ Casey Lowary

 
	 	 	Name:	 	Casey Lowary
	 	 	Title:	 	Director
	

 	
 	
By:	
 	
/s/ Darrell Holley

 
	 	 	Name:	 	Darrell Holley
	 	 	Title:	 	Managing Director

Signature Page 9

 

					
	 	 	SUNTRUST BANK,

as Co-Documentation Agent and Lender
	

 	
 	
By:	
 	
/s/ Andrew Johnson

 
	 	 	Name:	 	Andrew Johnson
	 	 	Title:	 	Director

Signature Page 10

 

					
	 	 	U.S. BANK NATIONAL ASSOCIATION,

as Co-Documentation Agent, Lender

and Increasing Lender
	

 	
 	
By:	
 	
/s/ Justin M. Alexander

 
	 	 	Name:	 	Justin M. Alexander
	 	 	Title:	 	Vice President

Signature Page 11

 

					
	 	 	WELLS FARGO BANK, N.A.,

as a Lender
	

 	
 	
By:	
 	
/s/ Oleg Kogan

 
	 	 	Name:	 	Oleg Kogan
	 	 	Title:	 	Vice President

Signature Page 12

 

					
	 	 	BNP PARIBAS,

as a Lender
	

 	
 	
By:	
 	
/s/ Gregory E. George

 
	 	 	Name:	 	Gregory E. George
	 	 	Title:	 	Managing Director
	

 	
 	
BNP Paribas,

as a Lender
	

 	
 	
By:	
 	
/s/ Greg Smothers

 
	 	 	Name:	 	Greg Smothers
	 	 	Title:	 	Director

Signature Page 13

 

					
	 	 	CALYON NEW YORK BRANCH,

as a Lender
	

 	
 	
By:	
 	
 

 
	 	 	Name:	 	 
	 	 	Title:	 	 
	

 	
 	
By:	
 	
 

 
	 	 	Name:	 	 
	 	 	Title:	 	 

Signature Page 14

 

					
	 	 	BANK OF AMERICA, N.A.,

as a Lender
	

 	
 	
By:	
 	
 

 
	 	 	Name:	 	 
	 	 	Title:	 	 

Signature Page 15

 

					
	 	 	DEUTSCHE BANK TRUST COMPANY AMERICAS,

as a Lender and Increasing Lender
	

 	
 	
By:	
 	
/s/ Erin Morrissey

 
	 	 	Name:	 	Erin Morrissey
	 	 	Title:	 	Vice President
	

 	
 	
By:	
 	
/s/ Mary Kay Coyle

 
	 	 	Name:	 	Mary Kay Coyle
	 	 	Title:	 	Managing Director

Signature Page 16

 

					
	 	 	BANK OF SCOTLAND PLC

NEW YORK BRANCH,

as a Lender
	

 	
 	
By:	
 	
/s/ Julia R. Franklin

 
	 	 	Name:	 	Julia R. Franklin
	 	 	Title:	 	Assistant Vice President

Signature Page 17

 

					
	 	 	MORGAN STANLEY BANK,

as a Lender and Increasing Lender
	

 	
 	
By:	
 	
/s/ Christopher Whelan

 
	 	 	Name:	 	Christopher Whelan
	 	 	Title:	 	Senior Credit Officer

Signature Page 18

 

					
	 	 	WESTLB AG,

NEW YORK BRANCH,

as a Lender
	

 	
 	
By:	
 	
 

 
	 	 	Name:	 	 
	 	 	Title:	 	 

Signature Page 19

 

					
	 	 	COMPASS BANK,

as a Lender and Increasing Lender
	

 	
 	
By:	
 	
/s/ Greg Determann

 
	 	 	Name:	 	Greg Determann
	 	 	Title:	 	Vice President

Signature Page 20

 

					
	 	 	CREDIT SUISSE, CAYMAN ISLANDS BRANCH

as a Lender
	

 	
 	
By:	
 	
/s/ Nupur Kumar

 
	 	 	Name:	 	Nupur Kumar
	 	 	Title:	 	Vice President
	

 	
 	
By:	
 	
/s/ Shaheen Malik

 
	 	 	Name:	 	Shaheen Malik
	 	 	Title:	 	Vice President

Signature Page 21

 

					
	 	 	UNION BANK OF CALIFORNIA, N.A.,

as a Lender
	

 	
 	
By:	
 	
/s/ Union Bank of California

 
	 	 	Name:	 	Joshua Patterson
	 	 	Title:	 	Assistant Vice President

Signature Page 22

 

					
	 	 	COMERICA BANK,

as a Lender
	

 	
 	
By:	
 	
/s/ Caroline M. McClurg

 
	 	 	Name:	 	Caroline M. McClurg
	 	 	Title:	 	Vice President

Signature Page 23

 

					
	 	 	NATIXIS,

as a Lender
	

 	
 	
By:	
 	
/s/ Louis P. Laville, III

 
	 	 	Name:	 	Louis P. Laville, III
	 	 	Title:	 	Managing Director
	

 	
 	
By:	
 	
/s/ Daniel Payer

 
	 	 	Name:	 	Daniel Payer
	 	 	Title:	 	Director

Signature Page 24

 

					
	 	 	GUARANTY BANK, FSB,

as a Lender
	

 	
 	
By:	
 	
/s/ David M. Butler

 
	 	 	Name:	 	David M. Butler
	 	 	Title:	 	SVP

Signature Page 25

 

					
	 	 	AMEGY BANK, NATIONAL ASSOCIATION,

as a Lender
	

 	
 	
By:	
 	
/s/ Gregory J. Petruska

 
	 	 	Name:	 	Gregory J. Petruska
	 	 	Title:	 	Senior Vice President

Signature Page 26

 

					
	 	 	BANK OF OKLAHOMA, N.A.,

as a Lender
	

 	
 	
By:	
 	
/s/ Michael M. Logan

 
	 	 	Name:	 	Michael M. Logan
	 	 	Title:	 	Senior Vice President

Signature Page 27

 

					
	 	 	SOCIÉTÉ GÉNÉRALE,

as a Lender
	

 	
 	
By:	
 	
/s/ Stephen W. Warfel

 
	 	 	Name:	 	Stephen W. Warfel
	 	 	Title:	 	Managing Director

Signature Page 28

 

					
	NEW LENDER:	 	BARCLAYS BANK PLC,

as a New Lender
	

 	
 	
By:	
 	
/s/ Maria Lund

 
	 	 	 	 	Maria Lund
	 	 	 	 	Vice President

Signature Page 29

QuickLinks

FIRST AMENDMENT TO CREDIT AGREEMENTQuickLinks
 -- Click here to rapidly navigate through this document

 

 Exhibit 10.2  

SPECIFIC TERMS IN THIS EXHIBIT HAVE BEEN REDACTED BECAUSE CONFIDENTIAL TREATMENT FOR THOSE TERMS HAS BEEN REQUESTED. THE REDACTED MATERIAL HAS BEEN SEPERATELY FILED WITH THE
SECURITIES AND EXCHANGE COMMISSION, AND THE TERMS HAVE BEEN MARKED AT THE APPROPRIATE PLACE WITH TWO ASTERISKS (**).

Execution Version  

 
    CONTRIBUTION AGREEMENT    
    
    BY AND AMONG    
    
    MARKWEST LIBERTY GAS GATHERING, L.L.C.,    
    
    M&R MWE LIBERTY, LLC,    
    
    AND    

  
    MARKWEST LIBERTY MIDSTREAM & RESOURCES, L.L.C.    
    

 

 
 

  TABLE OF CONTENTS    
    

					
	 
	 	 
	 	Page 
	ARTICLE 1

DEFINITIONS; INTERPRETATION
	
 Section 1.1	
 	
Definitions	
 	
1
	Section 1.2	 	Headings; References; Interpretation	 	1
	

ARTICLE 2

CONTRIBUTIONS, ASSUMED LIABILITIES AND CLOSING
	
 Section 2.1	
 	
Contributions and Payments	
 	
2
	Section 2.2	 	Assumption of Liabilities	 	2
	Section 2.3	 	Closing	 	3
	Section 2.4	 	Closing Deliveries	 	3
	

ARTICLE 3

REPRESENTATIONS AND WARRANTIES OF MWE LIBERTY
	
 Section 3.1	
 	
Organization; Qualification	
 	
4
	Section 3.2	 	Authority; Enforceability	 	4
	Section 3.3	 	No Violation; Consents and Approvals	 	5
	Section 3.4	 	Capitalization	 	5
	Section 3.5	 	Compliance with Law	 	6
	Section 3.6	 	No Default	 	6
	Section 3.7	 	Title to Properties and Assets	 	6
	Section 3.8	 	Rights-of-Way	 	6
	Section 3.9	 	Financial Statements	 	7
	Section 3.10	 	Environmental Matters	 	7
	Section 3.11	 	Material Contracts	 	8
	Section 3.12	 	Legal Proceedings	 	8
	Section 3.13	 	Permits	 	8
	Section 3.14	 	Taxes	 	8
	Section 3.15	 	Employees	 	8
	Section 3.16	 	Brokers' Fee	 	9
	Section 3.17	 	Insurance	 	9
	Section 3.18	 	Intellectual Property	 	9
	Section 3.19	 	Affiliate Transactions	 	9
	

ARTICLE 4

REPRESENTATIONS AND WARRANTIES OF NGPMR
	
 Section 4.1	
 	
Organization	
 	
9
	Section 4.2	 	Authority; Enforceability	 	10
	Section 4.3	 	No Violation; Consents and Approvals	 	10
	Section 4.4	 	Brokers' Fee	 	10
	

ARTICLE 5

INDEMNIFICATION
	
 Section 5.1	
 	
Survival	
 	
10
	Section 5.2	 	Indemnification by the Company	 	11
	Section 5.3	 	Indemnification by MWE Liberty	 	11
	Section 5.4	 	Indemnification by NGPMR	 	11

i

 

					
	 
	 	 
	 	Page 
	Section 5.5	 	No Effect on Services Agreement and Company Operating Agreement	 	12
	Section 5.6	 	Third Party Claims Procedures	 	12
	Section 5.7	 	Satisfaction of Claims for Indemnification	 	13
	Section 5.8	 	Limits on Indemnification	 	13
	Section 5.9	 	Extent of Indemnification	 	14
	Section 5.10	 	No Reliance	 	14
	

ARTICLE 6

COVENANTS
	
 Section 6.1	
 	
HSR Filing	
 	
15
	Section 6.2	 	Tax Effect	 	15
	Section 6.3	 	Tax Matters	 	15
	Section 6.4	 	Further Assurances	 	16
	Section 6.5	 	Consents	 	17
	Section 6.6	 	Expenses	 	17
	Section 6.7	 	Public Statements	 	17
	Section 6.8	 	Conduct of Business	 	17
	

ARTICLE 7

CONDITIONS PRECEDENT
	
 Section 7.1	
 	
Conditions to Each Party's Obligations	
 	
18
	Section 7.2	 	Conditions to NGPMR's Obligations	 	18
	Section 7.3	 	Conditions to MWE Liberty's Obligations	 	19
	

ARTICLE 8

TERMINATION
	
 Section 8.1	
 	
Termination	
 	
19
	Section 8.2	 	Effect of Termination	 	20
	

ARTICLE 9

GENERAL PROVISIONS
	
 Section 9.1	
 	
Effective Time	
 	
20
	Section 9.2	 	Costs; Taxes	 	20
	Section 9.3	 	Notices	 	20
	Section 9.4	 	Binding Effect	 	21
	Section 9.5	 	No Third Party Rights	 	21
	Section 9.6	 	No Waiver	 	22
	Section 9.7	 	Applicable Law	 	22
	Section 9.8	 	Severability	 	22
	Section 9.9	 	Amendment or Modification	 	22
	Section 9.10	 	Assignment; Deed; Bill of Sale	 	22
	Section 9.11	 	Conspicuousness of Provisions	 	22
	Section 9.12	 	Counterparts	 	22
	Section 9.13	 	No Recourse Against Officers or Directors	 	23
	Section 9.14	 	Entire Agreement; Supersedure	 	23

ii

 

			
	EXHIBITS	 	 
	
 Exhibit A	
 	
Defined Terms
	Exhibit B	 	Assets
	Exhibit C	 	Company Operating Agreement
	Exhibit D	 	Services Agreement
	Exhibit E	 	Bill of Sale, Assignment and Assumption Agreement
	
 SCHEDULES	
 	

 
	
 Schedule 1.1	
 	
Knowledge Individuals
	Schedule 3.3	 	Consents or Approvals
	Schedule 3.4(b)	 	Capitalization
	Schedule 3.6	 	No Default
	Schedule 3.7(a)	 	Title to Properties and Assets
	Schedule 3.7(b)	 	Valid Transfer of Properties and Assets
	Schedule 3.8	 	Rights-of-Way
	Schedule 3.9	 	Trial Balance
	Schedule 3.10	 	Environmental Matters
	Schedule 3.11	 	Material Contracts
	Schedule 3.15(a)	 	Employees
	Schedule 3.15(b)	 	Benefit Plans
	Schedule 3.18	 	Intellectual Property
	Schedule 3.19	 	Affiliate Transactions
	Schedule 5.3(d)	 	Specific Indemnity Items **
	Schedule 5.3(e)	 	Specific Indemnity Items **
	Schedule 7.2(c)	 	Required Consents

iii

 

 
 

  CONTRIBUTION AGREEMENT    
    

        THIS CONTRIBUTION AGREEMENT, dated as of January 22, 2009, is entered into by
and among MarkWest Liberty Gas Gathering, L.L.C., a Delaware limited liability company ("MWE Liberty"), M&R MWE Liberty, LLC, a Delaware limited
liability company ("NGPMR"), and MarkWest Liberty Midstream & Resources, L.L.C., a Delaware limited liability company (the
"Company"). The parties to this Agreement are collectively referred to herein as the "Parties." 

 R E C I T A L S  

        WHEREAS, MWE Liberty has formed the Company, pursuant to the Act, for the purpose of engaging in the natural gas midstream business,
including, but not limited to, natural gas gathering and processing, and the natural gas liquids processing, fractionation, transportation, storage and marketing business within the Area of Mutual
Interest and certain other purposes (the "Business"); 

        WHEREAS,
at the Closing MWE Liberty and NGPMR (the "Members") shall execute and agree to that certain Amended and Restated Limited
Liability Company Agreement of the Company (the "Company Operating Agreement") in the form attached hereto as
Exhibit C, which Company Operating Agreement shall become effective at the Closing; 

        WHEREAS,
at the Closing MWE Liberty, MarkWest Hydrocarbon, Inc. and the Company shall execute and agree to that certain Services Agreement (the "Services
Agreement") in the form attached hereto as Exhibit D, which Services Agreement shall become effective at the Closing; 

        WHEREAS,
subject to the terms and conditions of this Agreement, NGPMR desires to contribute to the Company, and the Company desires to accept from NGPMR, certain cash consideration in
exchange for all of the Class A Interests; and 

        WHEREAS,
subject to the terms and conditions of this Agreement, MWE Liberty desires to contribute, convey, assign and transfer to the Company, and the Company desires to accept from MWE
Liberty, all of MWE Liberty's right, title and interest in and to the Assets in exchange for all of the Class B Interests and the assumption of certain liabilities by the Company. 

 A G R E E M E N T S  

        NOW, THEREFORE, in consideration of their mutual undertakings and agreements hereunder, the Parties undertake and agree as follows: 

 
 

  ARTICLE 1
  DEFINITIONS; INTERPRETATION  
    

        Section 1.1    Definitions.    Capitalized terms used in this Agreement but not defined
in the body hereof shall have the meanings ascribed to them in Exhibit A. 

        Section 1.2    Headings; References; Interpretation.    In this Agreement, unless a
clear contrary intention appears: (a) the singular includes the plural and vice versa; (b) reference to a person includes such Person's successors and assigns but, in the case of a
Party, only if such successors and assigns are permitted by this Agreement, and reference to a Person in a particular capacity excludes such Person in any other capacity; (c) reference to any
gender includes each other gender; (d) reference to any agreement (including this Agreement), document or instrument means such agreement, document, or instrument as amended or modified and in
effect from time to time in accordance with the terms thereof and, if applicable, the terms of this Agreement; (e) reference to any Section or Article means such Section or Article of this
Agreement, and references in any Section or Article or definition to any clause means such clause of such Section, Article or definition; (f) "hereunder," "hereof," "hereto" and words of
similar import are references to this Agreement as a whole and not to any particular provision hereof; and (g) the word "or" is not exclusive, and the word "including" (in its various forms)
means including without limitation. Section titles and headings in this Agreement are inserted for convenience 

 

of
reference only and are not intended to be a part of, or to affect the meaning or interpretation of, this Agreement. 

 
 

  ARTICLE 2
  CONTRIBUTIONS, ASSUMED LIABILITIES AND CLOSING  
    

        Section 2.1    Contributions and Payments.    Subject to the terms and conditions of
this Agreement, at the Closing, the following contributions, equity issuances and payments shall be made: 

        (a)   NGPMR
shall contribute $50,000,000.00 to the Company in immediately available funds in exchange for all of the Class A Interests. In its capacity as a holder of
such interests, NGPMR shall have the obligations set forth in the Company Operating Agreement with respect to a Class A Member to contribute additional capital to the Company, but shall have no
other obligation to contribute any additional capital to the Company. 

        (b)   MWE
Liberty shall grant, contribute, bargain, convey, assign, transfer, set over and deliver to the Company, its successors and assigns, and for its and their own use
forever, all of MWE Liberty's right,
title and interest in and to the Assets in exchange for all of the Class B Interests. In its capacity as a holder of such interests, MWE Liberty shall have the obligations set forth in the
Company Operating Agreement with respect to a Class B Member to contribute additional capital to the Company, but shall have no other obligation to contribute any additional capital to the
Company. The term "Assets" shall mean (i) all of the assets owned by MWE Liberty, including the natural gas gathering systems described in
Exhibit B attached hereto, together with all natural gas gathering and processing and natural gas liquids processing, fractionation, transportation, storage and
marketing plants and facilities constituting a part thereof or related thereto, and all easements, rights of way, privileges, franchises, tracts of land, surface leases, other interests in land,
pipelines, equipment, permits, licenses, contract rights and personal property constituting a part thereof or necessary for the ownership and operation thereof including the easements, rights of way,
permits and other instruments referenced in Exhibit B and (ii) all of the assets owned by Affiliates of MWE Liberty that are related exclusively to the
Business within the Area of Mutual Interest, but in any event, excluding any and all amounts payable by Range Resources-Appalachia, LLC pursuant to Section 4.3(d) of that certain Interim
Gas Processing Agreement dated March 5, 2008, between MarkWest Energy Appalachia, L.L.C. and Range Resources-Appalachia, LLC, for procuring, constructing and installing the interim plant
prior to January 1, 2008 and representing 115% of all Installation Costs (as defined therein) incurred in the procurement, construction and installation of the interim plant (the
"Excluded Assets"). The Excluded Assets shall be retained by MWE Liberty and its Affiliates and shall not be considered Assets hereunder. 

        (c)   The
Company shall pay to MWE Liberty in immediately available funds the amount of any **; provided that any such ** by
MWE Liberty after the date hereof shall be consistent with Section 6.8. 

        Section 2.2    Assumption of Liabilities.    As part of the consideration for the
contribution of the Assets by MWE Liberty to the Company, effective as of the Closing, the Company will assume and agree to duly and timely pay, perform and discharge, pursuant to the Assignment and
Assumption, all of the liabilities and obligations of any kind whatsoever of MWE Liberty arising from or relating to the Assets, whether known or unknown, liquidated or contingent, and regardless of
whether the same are deemed to have arisen, accrued or are attributable to periods prior to, on or after the Closing Date, including, but not limited to, obligations and liabilities of MWE Liberty:
(a) concerning the use, ownership, management or operation of the Assets, (b) under or relating to any contracts, agreements, Permits and instruments existing as of the Closing Date by
which the Assets are bound or subject or that relate to or are otherwise applicable to the Assets (other than obligations of MWE Liberty under 

2

 

the
Transaction Documents) and (c) which are Disclosed Liabilities, (all of the liabilities and obligations described in this Section 2.2 are collectively
referred to as the "Assumed Liabilities"); provided, however, that the Company does not assume (and
Assumed Liabilities shall not include) any costs or expenses included within the amount of MWE Liberty's initial capital contribution to the Company. 

        Section 2.3    Closing.    Subject to the terms and conditions of this Agreement, the
closing of the transactions contemplated by this Agreement (the "Closing") shall take place at the offices of Vinson & Elkins LLP, First
City Tower, 1001 Fannin Street, Suite 2500, Houston, Texas 77002 on the second Business Day after all of the conditions precedent set forth in Article 7 have
been satisfied, or if permissible, waived,
or at such other place, time and date as is agreed to in writing by the Parties (the "Closing Date"). The Closing will be deemed effective as of
11:59 p.m., Houston, Texas time on the Closing Date. 

        Section 2.4    Closing Deliveries.    

        (a)    NGPMR Deliveries.    At the Closing, NGPMR will execute and deliver, or cause to
be executed and delivered, to the other Parties, as applicable, each of the following documents, where the execution or delivery of documents is contemplated, and will take or cause to be taken the
following actions, where the taking of action is contemplated: 

          (i)  a
certificate of the Secretary of State of the State of Delaware, dated not more than five days prior to the Closing Date, as to the existence and good standing of
NGPMR; 

         (ii)  a
certificate of an officer of NGPMR providing the following documents and certifying that each is a true and correct copy: (A) the Organizational Documents of
NGPMR and (B) resolutions of NGPMR's governing body authorizing the transactions contemplated hereby (including designation of the Persons authorized to execute this Agreement on behalf of
NGPMR and the Transaction Documents to which it is a party); 

        (iii)  a
duly executed counterpart of the Company Operating Agreement; and 

        (iv)  a
certificate of an officer of NGPMR, dated as of the Closing Date, certifying that all of the conditions set forth in
Sections 7.1(a) and 7.3(a) have been satisfied. 

        (b)    MWE Liberty Deliveries.    At the Closing, MWE Liberty will execute and deliver,
or cause to be executed and delivered, to the other Parties, as applicable, each of the following documents, where the execution or delivery of documents is contemplated, and will take or cause to be
taken the following actions, where the taking of action is contemplated: 

          (i)  a
certificate of the Secretary of State of the State of Delaware, dated not more than five days prior to the Closing Date, as to the existence and good standing of MWE
Liberty; 

         (ii)  a
certificate of an officer of MWE Liberty providing the following documents and certifying that each is a true and correct copy: (A) the Organizational
Documents of MWE Liberty and (B) resolutions of MWE Liberty's governing body authorizing the transactions contemplated hereby (including
designation of the Persons authorized to execute this Agreement on behalf of MWE Liberty and the Transaction Documents to which it is a party); 

        (iii)  a
duly executed counterpart of the Company Operating Agreement; 

        (iv)  a
duly executed counterpart of the Services Agreement; 

         (v)  counterparts
of the Bill of Sale, Assignment and Assumption Agreement, in substantially the form attached as Exhibit E hereto (the
"Assignment and Assumption"); and 

        (vi)  a
certificate of an officer of MWE Liberty, dated as of the Closing Date, certifying that all of the conditions specified in
Section 7.1(e) and Section 7.2(a) have been satisfied. 

3

 

        (c)    Company Deliveries.    At the Closing, MWE Liberty will cause the Company to
execute and deliver: 

          (i)  a
certificate of the Secretary of State of the State of Delaware, dated not more than five days prior to the Closing Date, as to the existence and good standing of the
Company; 

         (ii)  a
copy of the Certificate of Formation of the Company certified by the Secretary of State of the State of Delaware; 

        (iii)  a
duly executed counterpart of the Assignment and Assumption; and 

        (iv)  a
duly executed counterpart of the Services Agreement; 

        The
transactions described above, together with the issuance and sale of the Class A Interests and the Class B Interests pursuant to this Agreement and the entry into the
Company Operating Agreement,
are referred to herein as the "Transactions." The "Transaction Documents" shall mean this Agreement, the
Company Operating Agreement, and the Services Agreement. 

 
 

  ARTICLE 3
  REPRESENTATIONS AND WARRANTIES OF MWE LIBERTY  
    

        MWE Liberty hereby makes the following representations and warranties to the Company and NGPMR: 

        Section 3.1    Organization; Qualification.    Each of MWE Liberty and the Company is a
limited liability company duly formed, validly existing and in good standing under the laws of the State of Delaware and has all requisite limited liability company power and authority to own, lease
and operate its properties and to carry on its business, and is duly qualified, registered or licensed to do business as a foreign limited liability company and is in good standing in each
jurisdiction in which the property owned, leased or operated by it or the nature of the business conducted by it makes such qualification necessary, except where the failure to be so duly qualified,
registered or licensed and in good standing would not have or be reasonably expected to have, individually or in the aggregate, a Material Adverse Effect. 

        Section 3.2    Authority; Enforceability.    

        (a)   Each
of MWE Liberty and the Company has the requisite limited liability company power and authority to execute and deliver the Transaction Documents to which it is a
party, and to consummate the Transactions. The execution and delivery by MWE Liberty and the Company of the Transaction Documents to which either of them is a party, and the consummation by MWE
Liberty and the Company of the Transactions, have been duly and validly authorized by MWE Liberty and/or the Company, as applicable, and no other limited liability company proceedings on the part of
MWE Liberty or the Company are necessary to authorize the Transaction Documents or to consummate the Transactions. 

        (b)   Each
of the Transaction Documents to which MWE Liberty or the Company is a party has been (or will be, in the case of Transaction Documents to be delivered at the
Closing) duly executed and delivered by MWE Liberty and/or the Company, as applicable, and, assuming the due authorization, execution and delivery by the other parties thereto, each Transaction
Document constitutes (or will constitute, in the case of Transaction Documents to be delivered at the Closing) the valid and binding agreement of MWE Liberty and the Company, and is enforceable
against MWE Liberty and/or the Company, as applicable, in accordance with its terms, except as such enforceability may be limited by applicable bankruptcy, insolvency, fraudulent transfer,
reorganization, moratorium and similar laws relating to or affecting creditors' rights generally and by general principles of equity (regardless of whether such enforceability is considered in a
proceeding in equity or at law). 

4

 

        Section 3.3    No Violation; Consents and Approvals.    Except as set forth on
Schedule 3.3: 

        (a)   The
execution, delivery and performance of the Transaction Documents by MWE Liberty and the Company and the consummation by MWE Liberty and the Company of the
Transactions do not and will not: (i) result in any breach of any provision of the organizational, governing or charter documents, as amended, of MWE Liberty or the Company;
(ii) constitute a default (or an event that with notice or lapse of time or both would give rise to a default) under, or give rise to any right of termination, cancellation, amendment or
acceleration (with or without notice, lapse of time or both) under any of the terms, conditions or provisions of any contract, note, bond, mortgage, indenture, license, agreement or other instrument
or obligation to which MWE Liberty or the Company is a party or by which any of the Assets is bound or affected, except to the extent that such default, termination, amendment, acceleration or
cancellation right (A) would not have or be reasonably expected to have, individually or in the aggregate, a Material Adverse Effect or (B) results from obtaining the Miscellaneous
Consents after the Closing pursuant to Section 6.5; (iii) result in a violation of any law, statute, rule, regulation, order, judgment, injunction, decree or
other restriction of any Governmental Authority to which MWE Liberty or the Company is subject (including federal and state securities laws and regulations) or by which any of the Assets is bound or
affected except as may result from obtaining the Miscellaneous Consents after the Closing pursuant to Section 6.5; or (iv) result in the creation or
imposition of any lien, charge or encumbrance upon any of the Assets, except for Permitted Liens or as may result from obtaining the Miscellaneous Consents and contractual consents listed on
Schedule 3.3 after the Closing pursuant to Section 6.5. 

        (b)   No
declaration, filing or registration with, or notice to, or authorization, consent or approval of, any Governmental Authority or other third party is necessary for the
consummation by MWE Liberty or the Company of the Transactions contemplated by the Transaction Documents, other than such declarations, filings, registrations, notices, authorization, consents or
approvals that have been or will be obtained or made prior to the Closing and other than the Miscellaneous Consents that may be obtained after the Closing pursuant to
Section 6.5. 

        (c)   No
consents are required under the Indentures to permit the consummation of the Transactions. 

        Section 3.4    Capitalization.    

        (a)   Except
for the Company, MWE Liberty does not (i) own, directly or indirectly, any capital stock, equity interests or other securities of any Person, or
(ii) have any Subsidiaries. 

        (b)   Except
as set forth on Schedule 3.4(b), prior to the Closing, the Company has not conducted any business operations, has no assets or
liabilities and is not a party to any contract or agreement of any kind or nature (other than the Organizational Documents of the Company). 

        (c)   Upon
Closing, the Class A Interests and the Class B Interests issued and sold pursuant to this Agreement (i) will constitute all of the issued and
outstanding membership interests of the Company and (ii) will be duly authorized, validly issued and fully paid (to the extent required under the Company Operating Agreement). Except as set
forth in the Company's Organizational Documents, there are no existing subscriptions, rights, warrants, calls, options, convertible or exchangeable securities, "phantom" equity rights, equity
appreciation rights, equity-based performance units, commitments, contracts, agreements or undertakings of any character to which the Company is bound: (i) obligating the Company to issue,
deliver or sell, or cause to be issued, delivered or sold, additional equity interests in, or any security convertible or exercisable for, or exchangeable into, any equity interest in the Company, or
(ii) obligating the Company to issue, grant, extend or enter into any such option, warrant, call, right, security, commitment, contract, arrangement or undertaking. There are no outstanding
contractual obligations of the Company to 

5

 

repurchase,
redeem or otherwise acquire any equity interests of the Company. There are no outstanding securities or other instruments convertible into or exchangeable for equity interests of the
Company and no commitments to issue such securities or instruments. Except as set forth in the Company's Organizational Documents, there are no voting trusts, proxies or other agreements or
understandings to which the Company is bound with respect to the voting of any equity interests or other securities of the Company. 

        Section 3.5    Compliance with Law.    (a) MWE Liberty is (and to MWE Liberty's
Knowledge has been) in compliance in all material respects with all Laws of any Governmental Authority applicable to the use, ownership and operation of the Assets; (b) MWE Liberty has not
received written notice of any material violation of any such Law relating to the use, ownership and operation of the Assets; and (c) MWE Liberty is not in material default or violation of any
order, writ, judgment, award, injunction or decree of any Governmental Authority applicable to the use, ownership or operation of the Assets. 

        Section 3.6    No Default.    MWE Liberty is not in violation of its organizational,
governing or charter documents. Except as set forth on Schedule 3.6, MWE Liberty is not in default, and no event has occurred which, with notice or lapse of time or
both, would give rise to a default, under, or give to others any rights of termination, amendment, acceleration or cancellation of or under, any agreement, credit facility, debt or other instrument
(evidencing a debt or other obligation of MWE Liberty) to which MWE Liberty is a party, by which any of the Assets are bound or affected, except to the extent that such default, termination,
amendment, acceleration or cancellation right (i) would not have or be reasonably expected to have, individually or in the aggregate, a Material Adverse Effect or (ii) results from
obtaining the Miscellaneous Consents after the Closing pursuant to Section 6.5. 

        Section 3.7    Title to Properties and Assets.    Except as set forth on
Schedule 3.7(a), MWE Liberty and its Affiliates have good, valid and defensible title to all real property (other than real property and buildings held under lease
by MWE Liberty) and personal property to be transferred pursuant to this Agreement and the constituent documents contemplated hereby, free and clear of all liens, encumbrances, security interests,
equities, charges or claims or other restrictions whatsoever, except for Permitted Liens. With respect to any real property and buildings held under lease by MWE Liberty or its Affiliates, such real
property and buildings are held under valid and subsisting and enforceable leases with such exceptions as do not materially interfere with the present or intended use of such properties by MWE Liberty
and its Affiliates taken as a whole. Except as set forth on Schedule 3.7(b), pursuant to the Assignment and Assumption, MWE Liberty and its Affiliates are validly
transferring at Closing all of their ownership interests in the Assets to the Company, and the Assets so transferred (together with the Services (as defined in the Services Agreement) to be provided
pursuant to the Services Agreement) constitute all rights and properties necessary in all material respects to operate the Business in a manner consistent with MWE Liberty's operation of the Business
immediately prior to the Closing, other than the Miscellaneous Consents and contractual consents listed on Schedule 3.3 that may be obtained after the Closing
pursuant to Section 6.5. 

        Section 3.8    Rights-of-Way.    Except as set forth on
Schedule 3.8, the Company, as of Closing, will have such easements or rights-of-way from each person (collectively,
"Rights-of-Way") as are necessary in all material respects to use, own and operate the Assets in the manner the Assets were
used, owned and operated by MWE Liberty immediately prior to the Closing. Except as set forth on Schedule 3.8, MWE Liberty has fulfilled and performed all of its
material obligations with respect to such Rights-of-Way and no event has occurred that allows, or after notice or lapse of time would allow, revocation or termination thereof
or would result in any impairment of the rights of the holder of any such Rights-of-Way, except for such revocations, terminations and impairments that would not have a
Material Adverse Effect and the Miscellaneous Consents that may be obtained after the Closing pursuant to Section 6.5. 

6

 

        Section 3.9    Financial
Statements.    Schedule 3.9 is an accurate copy of the trial balance (the "Trial
Balance") of MWE Liberty as of December 31, 2008 (the "Trial Balance Date") which accurately reflects the assets and
material liabilities of MWE Liberty as of such date subject to normal year-end adjustments. Except as set forth on Schedule 3.9, since the Trial Balance
Date, there has not been any change in financial condition, properties, assets, liabilities, business or results of operations of the Business, which, individually or in the aggregate, has had or is
reasonably likely to have a Material Adverse Effect. Since the Trial Balance Date, the Company has not incurred any obligation or liability (whether accrued, absolute, contingent or otherwise) of the
type required to be reflected on a consolidated balance sheet of the Company prepared in accordance with GAAP applied on a basis consistent with the Trial Balance except liabilities and obligations
incurred in the ordinary course of business and consistent with the Initial Budget or Section 6.8 hereof. 

        Section 3.10    Environmental Matters.    Except as set forth in
Schedule 3.10: 

        (a)   MWE
Liberty and the Assets and operations thereof, are and, during the relevant time periods specified in all applicable statutes of limitations, have been in compliance
in all material respects with Environmental Laws; 

        (b)   MWE
Liberty possesses, and is in compliance in all material respects with, all Environmental Permits for MWE Liberty's operation of the Assets as presently conducted and
such Permits are in full force and effect subject to obtaining the Miscellaneous Consents after the Closing pursuant to Section 6.5; 

        (c)   MWE
Liberty is not subject to any pending or, to MWE Liberty's Knowledge, threatened, Proceeding with respect to its operation of the Assets, nor has MWE Liberty
received any written notice of violation, noncompliance, or enforcement with respect to its operation of the Assets that remains pending or any written notice that it is or is suspected of being a
potentially responsible party under CERCLA or any similar law with respect to its operation of the Assets that remains pending, or any written notice of investigation, remediation or request for
information pursuant to Environmental Law from any Governmental Authority with respect to operation of the Assets that would reasonably be expected to result in a material liability to MWE Liberty
pursuant to Environmental Laws, which notice of investigation, remediation or request for information remains pending; 

        (d)   Except
for such matters that would not reasonably be expected to give rise to any material liability, costs or remedial or corrective action obligations under
Environmental Laws, (i) there has been no Release or, to MWE Liberty's Knowledge, threatened Release of Hazardous Substances by MWE Liberty or, to MWE Liberty's Knowledge, any third party; and
(ii) no Hazardous Substances are present in, on, at, under or from any of the Assets, or otherwise in connection with the operation of the Assets by MWE Liberty; 

        (e)   In
connection with the operation of the Assets, MWE Liberty has not assumed or retained by written contract, or to MWE Liberty's Knowledge, by operation of law, any
material liabilities (including STRICT LIABILITY) under any Environmental Laws for any Hazardous Substances; and 

        (f)    MWE
Liberty has made available to NGPMR and the Company complete and correct copies of all environmental assessment and audit reports and studies in its possession
addressing potentially material environmental liabilities or obligations relating to MWE Liberty or its operation of the Assets. 

        Notwithstanding
any other provisions of this Agreement to the contrary, this Section 3.10 contains the sole and exclusive representations and
warranties of MWE Liberty on environmental matters, including
Environmental Laws, Environmental Claims, Environmental Responses, Environmental Permits and Hazardous Substances. 

7

 

        Section 3.11    Material Contracts.    Each Material Contract is valid, binding and
enforceable in accordance with its terms, and is in full force and effect. MWE Liberty has provided to NGPMR a true and complete copy of each Material Contract. MWE Liberty has not received any
written notice of default under any Material Contract in the 12-month period prior to the date of this Agreement. Except as set forth on Schedule 3.11,
there are no (a) uncured defaults of MWE Liberty under any Material Contract that would give the counterparty thereto the right to terminate such Material Contract and (b) to MWE
Liberty's Knowledge, defaults by any of the counterparties to such Material Contracts. 

        Section 3.12    Legal Proceedings.    There are no Proceedings pending or, to the MWE
Liberty's Knowledge, threatened, against MWE Liberty, the Company or the Assets. To MWE Liberty's Knowledge, there are no events or circumstances that have occurred which would reasonably be expected
to result in Proceedings against MWE Liberty, the Company or the Assets. 

        Section 3.13    Permits.    MWE Liberty has, and upon Closing, MWE Liberty will
transfer to the Company and the Company will have (or have the benefit of pursuant to Section 6.5), all permits, approvals, consents, licenses, franchises,
exemptions and other governmental authorizations, consents and approvals (collectively, "Permits") necessary to use, own and operate the Assets as
presently used, owned and operated, except for any such Permits the failure to have (or have the benefit of) would not, individually or in the aggregate, reasonably be expected to have a Material
Adverse Effect. MWE Liberty has not received any written notification that it is in violation of any material Permits. MWE Liberty is in material compliance with all Permits. 

        Section 3.14    Taxes.    All Tax Returns required to be filed with respect to MWE
Liberty and the Assets have been filed and all such Tax Returns are complete and correct in all material respects; all Taxes due relating to MWE Liberty and the Assets have been paid in full (whether
or not shown to be due on such Tax Returns). MWE Liberty has not received any written notice of deficiency or assessment from any taxing authority with respect to liabilities for Taxes of MWE Liberty
or associated with the ownership or operation of the Assets, which have not been fully paid or finally settled, unless being contested in good faith through appropriate proceedings and for which
adequate reserves have been established in the Trial Balance. All Taxes required to be withheld, collected or deposited by or with respect to MWE Liberty or associated with the ownership or operation
of the Assets have been timely withheld, collected or deposited as the case may be, and to the extent required, have been paid to the relevant taxing authority. There are no outstanding agreements or
waivers extending the applicable statutory periods of limitation for Taxes of MWE Liberty or that are associated with the ownership or operation of the Assets for any period. MWE Liberty, which was
formed on March 26, 2008, is treated
as a partnership or a disregarded entity for U.S. federal income Tax purposes and no election has been made to treat MWE Liberty as an association taxable as a corporation. 

        Section 3.15    Employees.    

        (a)   Except
as set forth on Schedule 3.15(a), (i) neither MWE Liberty nor the Company has or previously had any employees and
(ii) no Affiliate of MWE Liberty or the Company is a party to a collective bargaining agreement with its employees. 

        (b)   Except
as set forth on Schedule 3.15(b), neither MWE Liberty nor the Company sponsors, maintains, has liability under or has an
obligation to contribute to any "employee benefit plans" (within the meaning of Section 3(3) of the Employee Retirement Income Security Act of 1974, as amended
("ERISA"), including, without limitation, multiemployer plans within the meaning of Section 3(37) of ERISA), or any stock purchase, stock option,
severance, employment, change-in-control, fringe benefit, collective bargaining, bonus, incentive, deferred compensation, employee loan or any other employee benefit plans,
agreements, programs, policies or other arrangements, whether or not subject to ERISA (all such plans, agreements, programs, policies and 

8

 

arrangements,
collectively, the "Benefit Plans"). Neither MWE Liberty nor the Company, nor any of their ERISA Affiliates, have any liability under
Section 412 of the Code or Title IV of ERISA. 

        Section 3.16    Brokers' Fee.    Except for the fee payable to Morgan Stanley, which
shall be paid by MWE, no broker, finder or similar intermediary has acted for or on behalf of, or is entitled to any broker, finder or similar fee or other commission from MWE Liberty, the Company or
any of their Affiliates in connection with this Agreement or the transactions contemplated hereby. 

        Section 3.17    Insurance.    MWE Liberty has provided or made available to NGPMR and
the Company a true and complete list of all liability, property, workers' compensation and other insurance policies currently in effect that insure or relate to the Assets. 

        Section 3.18    Intellectual Property.    Except as set forth on
Schedule 3.18, (a) MWE Liberty owns or has the right to use, and upon Closing and subject to the Miscellaneous Consents to be obtained after the Closing
pursuant to Section 6.5, the Company will own or have the right to use pursuant to license, sublicense, agreement (including the Services Agreement) or otherwise
all items of Intellectual Property used in the operation of the Business as presently conducted, except for such Intellectual Property the failure of which to own or have the right to use, would not,
individually or in the aggregate, reasonably be expected to have a Material Adverse Effect, (b) no third party has asserted in writing delivered to
MWE Liberty a claim that MWE Liberty is infringing on the Intellectual Property of such third party and (c) to MWE Liberty's Knowledge, no third party is infringing on the Intellectual Property
owned by MWE Liberty. 

        Section 3.19    Affiliate Transactions.    Except as set forth
on Schedule 3.19, there are no existing agreements or transactions relating to the provision of material services (or otherwise providing for the payment of
material amounts) between MWE Liberty, on the one hand, and any of its officers, managers, directors, employees, or any of their respective Affiliates, on the other hand. Except for any ownership
interest in MWE, no officer, director, manager or employee of MWE Liberty has any direct or indirect material ownership interest in any Person with which MWE Liberty has any material business
relationship. 

 
 

  ARTICLE 4
  REPRESENTATIONS AND WARRANTIES OF NGPMR  
    

        NGPMR hereby makes the following representations and warranties to the Company: 

        Section 4.1    Organization.    NGPMR is a limited liability company duly formed,
validly existing and in good standing under the laws of the State of Delaware and has all requisite limited liability company power and authority to own, lease and operate its properties and to carry
on its business. 

9

 

        Section 4.2    Authority; Enforceability.    

        (a)   NGPMR
has the requisite limited liability company power and authority to execute and deliver the Transaction Documents to which it is a party, and to consummate the
Transactions. The execution and delivery by NGPMR of the Transaction Documents to which it is a party, and the consummation by NGPMR of the Transactions, have been duly and validly authorized by NGPMR
and no other limited liability company proceedings on the part of NGPMR is necessary to authorize the Transaction Documents or to consummate the Transactions. 

        (b)   Each
of the Transaction Documents to which NGPMR is a party has been (or will be, in the case of Transaction Documents to be delivered at Closing) duly executed and
delivered by NGPMR and, assuming the due authorization, execution and delivery by the other parties thereto, each Transaction Document to which NGPMR is a party constitutes (or will constitute, in the
case of Transaction Documents to be delivered at Closing) the valid and binding agreement of NGPMR, and is enforceable against NGPMR in accordance with its terms, except as such enforceability may be
limited by applicable bankruptcy, insolvency, fraudulent transfer, reorganization, moratorium and similar laws relating to or affecting creditors' rights generally and by general principles of equity
(regardless of whether such enforceability is considered in a proceeding in equity or at law). 

        Section 4.3    No Violation; Consents and Approvals.    

        (a)   The
execution, delivery and performance of the Transaction Documents by NGPMR and the consummation by NGPMR of the Transactions do not and will not: (i) result in
any breach of any provision of the Organizational Documents, as amended, of NGPMR; (ii) constitute a default (or an event that with notice or lapse of time or both would give rise to a default)
under, or give rise to any right of termination, cancellation, amendment or acceleration (with or without notice, lapse of time or both) under any of the terms, conditions or provisions of any
contract, note, bond, mortgage, indenture, license, agreement or other instrument or obligation to which NGPMR is a party or by which any of its
assets is bound, except to the extent that such default, termination, amendment, acceleration or cancellation right would not have or be reasonably expected to have, individually or in the aggregate,
a Material Adverse Effect; or (iii) result in a violation of any law, statute, rule, regulation, order, judgment, injunction, decree or other restriction of any Governmental Authority to which
NGPMR is subject (including federal and state securities laws and regulations) or by which any of its assets is bound. 

        (b)   Other
than the filings with respect to the HSR Act set forth in Section 6.1, no declaration, filing or registration with, or notice
to, or authorization, consent or approval of, any Governmental Authority is necessary for the consummation by NGPMR of the Transactions contemplated by the Transaction Documents, other than such
declarations, filings, registrations, notices, authorization, consents or approvals that have been obtained or made prior to the Closing. 

        Section 4.4    Brokers' Fee.    No broker, finder or similar intermediary has acted for
or on behalf of, or is entitled to any broker, finder or similar fee or other commission from NGPMR or any of its Affiliates, in connection with this Agreement or the transactions contemplated hereby. 

 
 

  ARTICLE 5
  INDEMNIFICATION  
    

        Section 5.1    Survival.    

        (a)   The
representations and warranties of MWE Liberty contained in Article 3 shall survive the Closing until the date that is ** after
the date of the Closing, with the exception that the representations and warranties in (i) ** shall survive the Closing until ** after the ** and (ii) ** shall survive **. The
representations and warranties of NGPMR contained in ** shall survive **, 

10

 

with
the exception that the representations and warranties in ** shall survive the Closing until the date that is ** after the date of the Closing. 

        (b)   All
covenants and agreements contained herein that by their terms are to be performed in whole or in part subsequent to the Closing, shall survive the Closing in
accordance with their terms; provided that the agreement by MWE Liberty to indemnify the NGPMR Covered Persons pursuant to ** shall
survive the Closing until the date that is ** after the Closing Date; provided further that the covenants contained in Section 6.3 shall survive **. 

        (c)   The
period of time a representation or warranty or covenant or agreement survives the Closing pursuant to this Section 5.1 shall be
the "Survival Period" with respect to such representation or warranty or covenant or agreement. In the event notice of any claim for indemnification
under this Article 5 shall have been asserted in writing within the applicable Survival Period and such claim has not been finally resolved by the expiration of
such Survival Period, the representations or warranties or covenants or agreements that are the subject of such claim shall survive, but only to the extent of the underlying facts of the claim (so
long as the facts or circumstances alleged to give rise to such claim have been specified in reasonable detail and are not based on speculative facts, circumstances or other events) as made prior to
the expiration of the Survival Period, until such claim is finally resolved. 

        Section 5.2    Indemnification by the Company.    

        (a)   Subject
to the terms of this Article 5, from and after the Closing, the Company shall indemnify, defend and hold harmless MWE Liberty
and its Affiliates and their respective directors, members, managers, stockholders, officers, partners, employees, agents, consultants, attorneys, representatives, successors, transferees and
assignees (collectively, the "MWE Liberty Covered Persons") from and against any losses, claims, damages, liabilities (including STRICT LIABILITY),
costs and expenses (including reasonable attorneys' fees and expenses), interest, penalties, judgments and settlements of any and every kind and character, known or unknown, fixed or contingent
(collectively, "Losses"), incurred, arising out of, or relating to, the Assumed Liabilities except to the extent such Losses arise from the same facts
and circumstances as a good faith indemnification claim by the Company or NGPMR pursuant to Section 5.3. 

        (b)   Subject
to the terms of this Article 5, from and after the Closing, the Company shall indemnify, defend and hold harmless the NGPMR
Covered Persons to the fullest extent permitted by law, from and against any Losses incurred, arising out of or related to those items set forth in Section 5.3 (for
which MWE Liberty has an obligation to indemnify the NGPMR Covered Persons) to the extent that MWE Liberty fails to remedy such Losses pursuant to Section 5.7(b). 

        Section 5.3    Indemnification by MWE Liberty.    Subject to the terms of this
Article 5, from and after the Closing, MWE Liberty shall indemnify, defend and hold harmless the Company, NGPMR and its Affiliates and their respective directors,
members, managers, stockholders, officers, partners, employees, agents, consultants, attorneys, representatives, successors, transferees and assignees (collectively, the "NGPMR
Covered Persons") to the fullest extent permitted by law, from and against any Losses, incurred, arising out of or relating to (a) any breach of any of the
representations or warranties (in each case, when made) of MWE Liberty contained in Article 3, (b) any breach of any of the covenants of MWE Liberty
contained in this Agreement, (c) the ownership, management or operation of the Assets prior to the Closing Date, other than the Specified Liabilities, (d) those items listed on
Schedule 5.3(d) or (e) those items listed on Schedule 5.3(e). It is acknowledged and agreed by the Parties that the
indemnity obligations of MWE Liberty under Section 5.3(d) and Section 5.3(e) shall ** by ** in the **. 

        Section 5.4    Indemnification by NGPMR.    Subject to the terms of this
Article 5, from and after the Closing, NGPMR shall indemnify and hold harmless the MWE Liberty Covered Persons, to the fullest 

11

 

extent
permitted by law, from and against Losses incurred, arising out of or relating to (i) any breach of any of the representations or warranties (in each case, when made) of NGPMR contained
in Article 4 or (ii) any breach of any of the covenants of NGPMR in this Agreement. 

        Section 5.5    No Effect on Services Agreement and Company Operating
Agreement.    Notwithstanding anything to the contrary contained in this Agreement, no provision of Section 5.2 or
Section 5.3 shall be construed to have any effect upon, or to otherwise limit, any indemnification obligation contained in the Services Agreement or the Company
Operating Agreement. 

        Section 5.6    Third Party Claims Procedures.    

        (a)   In
the event that any action, suit, claim or proceeding is commenced by a third party involving a claim for which a party required to provide indemnification hereunder
(an "Indemnifying Party") may be liable to a party entitled to indemnification (an "Indemnified Party")
hereunder (a "Third Party Claim"), the Indemnified Party shall promptly notify the Indemnifying Party in writing of such Third Party Claim indicating
the nature of such claim and the basis therefore (the "Claim Notice") and the Indemnifying Party shall assume the defense thereof, including the
employment of counsel reasonably satisfactory to the Indemnified Party and the payment of all fees and expenses incurred in connection with defense thereof; provided
that if the Indemnifying Party does not promptly take reasonable action to assume such defense, the Indemnified Party may lead the defense of such potentially indemnified claim
and the Indemnifying Party shall be liable for all additional costs and expenses incurred by the Indemnified Party in connection therewith, provided
further, that no failure of any Indemnified Party to give such Claim Notice and no delay on the part of the Indemnified Party in giving any such Claim Notice shall relieve the
Indemnifying Party of any indemnification obligation hereunder except (and only) to the extent that it shall be finally determined by a court of competent jurisdiction (which determination is not
subject to appeal or further review) that such failure shall have proximately and materially adversely prejudiced the Indemnifying Party. 

        (b)   An
Indemnified Party shall have the right to employ separate counsel in any such Proceeding and to participate in the defense thereof, but the fees and expenses of such
counsel shall be at the expense of such Indemnified Party or Parties unless: (i) the Indemnifying Party has agreed in writing to pay such fees and expenses; (ii) the Indemnifying Party
shall have failed promptly to assume the defense of such Proceeding and to employ counsel reasonably satisfactory to such Indemnified Party in any such Proceeding; or (iii) the named parties to
any such Proceeding (including any impleaded parties) include both such Indemnified Party and the Indemnifying Party, and such Indemnified Party shall have been advised by counsel that a conflict of
interest is likely to exist if the same counsel were to represent such Indemnified Party and the Indemnifying Party (in which case, if such Indemnified Party notifies the Indemnifying Party in writing
that it elects to employ separate counsel at the expense of the Indemnifying Party, such counsel shall be at the expense of the Indemnifying Party). It being understood, however, that the Indemnifying
Party shall not, in connection with any one such Proceeding, be liable for the fees and expenses of more than one separate firm of attorneys at any time for all Indemnified Parties, which firm shall
be appointed by a majority of the Indemnified Parties; provided, however, that in the case a single firm of attorneys would be inappropriate due to
actual or potential differing interests or conflicts between such Indemnified Parties and any other party represented by such counsel in such Proceeding or otherwise, then the Indemnifying Party shall
be liable for the fees and expenses of one additional firm of attorneys with respect to such Indemnified Parties. The Indemnifying Party shall not be liable for any settlement of any such Proceeding
effected without its written consent, which consent shall not be unreasonably withheld. No Indemnifying Party shall, without the prior written consent of the Indemnified Party (which in the event that
the Indemnified Party is the Company shall include the written consent of NGPMR, not to be unreasonably withheld), effect any settlement of any pending Proceeding in respect of which any 

12

 

Indemnified
Party is a party, unless (A) such settlement includes a full and unconditional release of such Indemnified Party from all liability on claims that are the subject matter of such
Proceeding, (B) does not contain any admission of wrongdoing or illegal conduct and (C) the Indemnifying Party has agreed in writing that it is liable to the Indemnified Party for an
indemnification payment in respect of the full amount of the settlement. 

        Section 5.7    Satisfaction of Claims for Indemnification.    

        (a)   The
Parties agree that in the event any Losses are determined to have been incurred as a result of an indemnification claim pursuant to
Section 5.3, MWE Liberty shall have the right to first satisfy and discharge any such Losses by either (i) ** for such Losses and/or (ii) ** such
Losses; provided that, (i) if and to the extent any such ** for any ** for which it is entitled to indemnity hereunder, MWE Liberty shall
indemnify NGPMR ** for any such Losses pursuant to Section 5.7(b) and (ii) in no event shall ** a claim for indemnification made pursuant to this
Article 5 has been satisfied **, or that ** any obligation hereunder, **. 

        (b)   In
the event that MWE Liberty fails to satisfy in full any Losses in accordance with Section 5.7(a) ** such Losses being finally
determined, MWE Liberty shall satisfy any such claim for indemnification by either (i) ** for any Losses incurred by NGPMR ** or (ii) having ** (as such term is defined in the Company
Operating Agreement) ** the amount of any such Company Loss that has not been satisfied
in full pursuant to Section 5.7(a); provided that ** set forth above by providing ** within 30 days of such
Losses being finally determined. In the event that unremedied Losses are to be indemnified pursuant to clause (ii) of this Section 5.7(b), MWE Liberty and
NGPMR shall ** the Company Operating Agreement ** an amount equal to such unremedied Loss. 

        Section 5.8    Limits on Indemnification.    

        (a)   In
calculating amounts payable to an Indemnified Party, the amount of any indemnified Losses shall be determined without duplication of any other Loss for which an
indemnification claim has been made or could be made under any other representation, warranty, covenant, or agreement and shall be computed net of (i) payments actually recovered by the
Indemnified Party under any insurance policy with respect to such Losses and (ii) any prior or subsequent actual recovery by the Indemnified Party from any Person with respect to such Losses
and (iii) any Tax Benefit accruing to any Indemnified Party on account of such Losses. 

        (b)   Notwithstanding
any other provision of this Agreement, in no event shall any Party be liable for punitive, special, incidental, indirect, consequential or lost profits
damages of any kind or nature, regardless of the form of action through which such damages are sought, except for any such damages recovered by any third party against any Party in respect of which
such Party would otherwise be entitled to indemnification pursuant to the terms hereof. 

        (c)   In
addition to being entitled to exercise all rights provided herein, including recovery of damages, the Parties will be entitled to specific performance under this
Agreement. The Parties agree that monetary damages may not be adequate compensation for any loss incurred by reason of any breach of obligations described in the foregoing sentence and hereby agree to
waive in any action for specific performance of any such obligation the defense that a remedy at law would be adequate. 

        (d)   If
the Closing occurs, neither the Company nor NGPMR will be entitled to indemnity under ** of this Agreement for Losses with respect to any claim under ** until the
aggregate amount of all such claims **, and thereafter, the Company and/or NGPMR shall ** Losses **; provided however, that all Losses resulting from or
arising out of any ** shall be indemnified against ** to the **. Except for a claim of actual fraud involving a knowing and intentional misrepresentation or omission of a material fact or willful or
intentional breach, in no event will 

13

 

the
aggregate liability of (i) ** under ** and (ii) ** under ** in respect of ** claims of ** under ** exceed **; provided, however, that
the aggregate liability of ** under ** with respect to ** shall not exceed **; provided, further that the aggregate liability of ** under ** in respect
of ** claims of ** under ** with respect to ** shall not exceed **. Notwithstanding anything to the contrary in this Agreement, in no event shall the aggregate liability of (i) ** arising under
this Agreement and from the transactions contemplated hereby exceed ** and (ii) ** arising under this Agreement and from the
transactions contemplated hereby exceed **. The reimbursement and indemnification obligations set forth in ** shall not be subject to any of the limitations set forth in this
Section 5.8. 

        (e)   In
no event shall the ** recovery of any Losses pursuant to this Article 5 be duplicative. 

        (f)    The
remedies provided in this Article 5 shall be the sole and exclusive legal remedies of the Parties, from and after the Closing,
with respect to this Agreement and the transactions contemplated hereby; provided that nothing in this
Section 5.8(f) shall prevent either Party from (i) seeking specific performance, injunctive and/or equitable relief for claims of breach or failure to
perform covenants performable under this Agreement at any time after the Closing or (ii) pursuing, and recovering in respect of, any claim based on actual fraud involving a knowing and
intentional misrepresentation or omission of a material fact or willful or intentional breach. 

        Section 5.9    Extent of Indemnification.    WITHOUT LIMITING THE SCOPE OF THE
INDEMNIFICATION, DISCLAIMER, RELEASE AND ASSUMPTION OBLIGATIONS SET FORTH IN THIS AGREEMENT, TO THE FULLEST EXTENT PERMITTED BY LAW, AN INDEMNIFIED PERSON SHALL BE ENTITLED TO INDEMNIFICATION
HEREUNDER IN ACCORDANCE WITH THE TERMS HEREOF, REGARDLESS OF WHETHER THE INDEMNIFIABLE LOSS GIVING RISE TO ANY SUCH INDEMNITY OBLIGATION IS THE RESULT OF THE SOLE, ACTIVE, PASSIVE, CONCURRENT OR
COMPARATIVE NEGLIGENCE, STRICT LIABILITY OR OTHER LEGAL FAULT OR VIOLATION OF ANY LAW OF OR BY ANY SUCH INDEMNIFIED PERSON. 

        Section 5.10    No Reliance.    THE REPRESENTATIONS AND WARRANTIES OF MWE LIBERTY
CONTAINED IN ARTICLE 3 CONSTITUTE THE SOLE AND EXCLUSIVE REPRESENTATIONS AND WARRANTIES OF MWE LIBERTY TO THE COMPANY IN CONNECTION WITH THE TRANSACTIONS CONTEMPLATED
HEREBY. THE REPRESENTATIONS AND WARRANTIES OF NGPMR CONTAINED IN ARTICLE 4 CONSTITUTE THE SOLE AND EXCLUSIVE REPRESENTATIONS AND WARRANTIES OF NGPMR TO THE COMPANY IN
CONNECTION WITH THE TRANSACTIONS CONTEMPLATED HEREBY. EXCEPT FOR SUCH REPRESENTATIONS AND WARRANTIES (IN EACH CASE, AS MODIFIED BY THE SCHEDULES HERETO), NONE OF MWE LIBERTY, THE COMPANY, NGPMR OR ANY
OTHER PERSON MAKES ANY OTHER EXPRESS OR IMPLIED REPRESENTATION OR WARRANTY WITH RESPECT TO SUCH PARTIES, THE ASSETS OR THE TRANSACTIONS CONTEMPLATED BY THIS AGREEMENT, AND EACH PARTY DISCLAIMS ANY
OTHER REPRESENTATIONS OR WARRANTIES, WHETHER MADE BY SUCH PARTIES OR ANY OF THEIR AFFILIATES, OFFICERS, DIRECTORS, EMPLOYEES, AGENTS OR REPRESENTATIVES (INCLUDING WITH RESPECT TO THE DISTRIBUTION TO,
OR ANY SUCH PERSON'S RELIANCE ON, ANY INFORMATION, DOCUMENTS OR OTHER MATERIAL MADE AVAILABLE TO SUCH PERSON IN ANY DATA ROOM, MANAGEMENT PRESENTATION OR IN ANY OTHER FORM IN EXPECTATION OF, OR IN
CONNECTION WITH, THE TRANSACTIONS CONTEMPLATED HEREBY). EXCEPT FOR SUCH REPRESENTATIONS AND WARRANTIES (IN EACH CASE, AS MODIFIED BY THE SCHEDULES HERETO), EACH PARTY HEREBY DISCLAIMS ALL LIABILITY
AND RESPONSIBILITY FOR ANY REPRESENTATION, WARRANTY, PROJECTION, FORECAST, STATEMENT, OR INFORMATION MADE, COMMUNICATED, OR FURNISHED (ORALLY OR IN WRITING) TO ANY OTHER PARTY OR ITS AFFILIATES,
OFFICERS, DIRECTORS, 

14

 

EMPLOYEES,
AGENTS OR REPRESENTATIVES (INCLUDING OPINION, INFORMATION, PROJECTION, OR ADVICE THAT MAY HAVE BEEN OR MAY BE PROVIDED TO ANY PARTY OR ANY DIRECTOR, OFFICER, EMPLOYEE, AGENT, CONSULTANT, OR
REPRESENTATIVE OF SUCH PARTY OR ANY OF ITS AFFILIATES). 

 
 

  ARTICLE 6
  COVENANTS  
    

        Section 6.1    HSR Filing.    

        (a)   As
promptly as reasonably possible following the execution of this Agreement, but in no event later than 10 Business Days following such date, NGPMR shall make such
filings as may be required under the Hart-Scott-Rodino Anti-Trust Improvements Act of 1976 ("HSR Act") with respect to the
transactions contemplated by this Agreement and, in making such filings, NGPMR
shall request early termination of the waiting period specified in the HSR Act. Thereafter, NGPMR shall file as promptly as possible all reports or other documents required or requested by the U.S.
Federal Trade Commission ("FTC") or the U.S. Department of Justice ("DOJ") pursuant to the HSR Act or
otherwise including requests for additional information concerning such transactions. Without limiting the foregoing, NGPMR and MWE Liberty shall use commercially reasonable efforts to cooperate and
oppose any preliminary injunction sought by any Governmental Authority under the HSR Act preventing the consummation of the transactions contemplated by this Agreement. NGPMR and MWE Liberty shall
cause their respective counsel to furnish the other party such necessary information and reasonable assistance as the other may reasonably request in connection with NGPMR's preparation of necessary
filings or submissions under the provisions of the HSR Act. NGPMR shall cause its counsel to supply to MWE Liberty copies of the date stamped receipt copy of the cover letters delivering the filings
or submissions required under the HSR Act to the FTC or DOJ, as applicable. Notwithstanding anything in this Section 6.1 to the contrary, neither NGPMR nor MWE, nor
any of their Affiliates, shall be required by this Section 6.1 to take any action that would require or result in holding separate or divesting assets or operations
of NGPMR, MWE Liberty or any of their Affiliates in order to have satisfied their obligation to use their commercially reasonable efforts under this Section 6.1. 

        (b)   The
cost all filing or application fees associated with filings under the HSR Act shall be **. Within two Business Days of filing under the HSR Act, **. 

        Section 6.2    Tax Effect.    

        (a)   None
of the Parties (nor such Parties' counsel or accountants) has made or is making any representations to any other Party (nor such Party's counsel or accountant)
concerning any of the Tax effects of the transactions provided for in this Agreement. Each Party hereto represents that it has obtained, or may obtain, independent Tax advice with respect thereto and
upon which it, if so obtained, has solely relied. 

        Section 6.3    Tax Matters.    

        (a)   Each
of the Parties agrees to cooperate fully with each other Party to enable each Party to more accurately determine its own tax liability and to minimize such
liability to the extent legally permissible. Each Party shall provide and make available to each other Party such records as a Party may reasonably request for the defense of any audit, examination,
administrative appeal or litigation of any Tax Return or other similar governmental report or form. 

        (b)   MWE
Liberty shall be liable for, and shall indemnify, defend and hold harmless the Company for, any and all liability for Taxes with respect to the Assets for any
taxable period ending on or before the Closing Date ("Pre-Closing Tax Period") and with respect to any taxable period that begins on or
before and ends after the Closing Date ("Straddle Period"), for the 

15

 

portion
thereof ending on the Closing Date. In the case of any Straddle Period, the amount of Taxes with respect to the Assets allocable to the portion of the Straddle Period ending on the Closing
Date shall be deemed to be the amount of such Taxes for the entire period (or, in the case of such Taxes determined on an arrears basis, the amount of such Taxes for the immediately preceding period)
multiplied by a fraction, the numerator of which is the number of calendar days in the applicable period ending on and including the Closing Date and the denominator of which is the number of calendar
days in the entire relevant period. 

        (c)   Ad
valorem property Taxes imposed on or with respect to the Assets for the taxable period (for purposes of this section, "taxable period" means the period beginning on
the assessment date for ad valorem property Taxes through the day before the next assessment date for such Taxes) that contains the Closing Date shall be prorated between MWE Liberty and Company based
on the relative number of days prior to the Closing Date and on and after the Closing Date during the taxable period, with MWE Liberty being responsible for such prorated ad valorem property Taxes for
the period prior to the Closing Date and Company being responsible for such prorated ad valorem property Taxes for the period beginning on the Closing Date. Upon receipt of the ad valorem property Tax
bills for the taxable period that contains the Closing Date, MWE Liberty shall calculate the prorated ad valorem property Taxes and shall bill Company for such amount, with Company making such payment
within 20 days of receipt of such bill. Company shall promptly forward to MWE Liberty any ad valorem property Tax bills for the taxable period that contains the Closing Date that are received
by Company. MWE Liberty shall be responsible as between MWE Liberty and Company for the payment of the total amount of ad valorem property Taxes imposed on or with respect to the Assets for the
taxable period that contains the Closing Date. 

        Section 6.4    Further Assurances.    From time to time after the Closing Date, and
without any further consideration, the Parties agree to, and MWE Liberty agrees to cause its Affiliates to, as applicable, execute, acknowledge and deliver all such additional deeds, assignments,
bills of sale, conveyances, instruments, notices, releases, acquittances and other documents, and will do all such other acts and things, all in accordance with applicable Laws, as may be reasonably
necessary to give effect to the transactions consummated by this Agreement and to collect and reduce to the possession of the Company the Assets and to effect the assumption by the Company of the
Assumed Liabilities. 

16

 

 

        Section 6.5    Consents.    Except for those consents listed on
Schedule 7.2(c), which are required to be obtained prior to the Closing, MWE Liberty shall use commercially reasonable efforts to obtain and, to the extent that any
Assets are held in the name of an Affiliate of MWE Liberty, cause its Affiliates to use commercially reasonable efforts to obtain, any other consents of third parties, including Governmental
Authorities, which are required to be obtained for the assignment of the Assets to the Company (the "Consents") prior to the Closing. Prior to obtaining
the Consents, any Asset that is not otherwise assignable or transferable (each a "Non-Assigned Asset") shall be deemed to be held by MWE
Liberty or such Affiliate, as applicable, at all times during the Holding Period in accordance with this Section. During the Holding Period, MWE Liberty shall and shall cause its Affiliates to, to the
extent MWE Liberty or its Affiliates may lawfully and validly do so, grant to the Company a non-exclusive right and license to use each such Non-Assigned Asset and provide the
Company with the economic benefits and risks of ownership of the Non-Assigned Assets, the intent of the parties being to provide the Company, to the extent the same can be reasonably done,
with the same access and ability to utilize such Non-Assigned Assets as if such Non-Assigned Assets had been included within the Assets. Upon receipt of the Consent related to
a Non-Assigned Asset, such Non-Assigned Asset shall automatically be deemed to be an Asset without the need for any further action on the part of the parties or any other
Person and without the payment of any additional consideration, but subject to the provisions of Section 6.4. The Company shall cooperate in good faith with MWE
Liberty and its Affiliates in connection with the pursuit of the Consents. 

        Section 6.6    Expenses.    Except to the extent otherwise specifically provided
herein, all costs and expenses incurred by NGPMR in connection with the Transaction Documents and the Transactions shall be paid by **, including all fees of its legal counsel, financial and business
advisers and accountants; provided that the ** to be **. MWE Liberty shall bear its own expenses incurred in connection with the Transaction Documents
and the Transactions whether or not the Transactions are consummated, including all fees of its legal counsel, financial and business advisers and accountants (which for clarity purposes shall include
the fees of Morgan Stanley). 

        Section 6.7    Public Statements.    The Parties shall consult with each other prior to
issuing any public announcement, statement or other disclosure with respect to this Agreement, the other Transaction
Documents or the transactions contemplated hereby or thereby and neither MWE Liberty on one hand nor NGPMR on the other shall issue any such public announcement, statement or other disclosure without
having first received the written consent of the other Party, except as may be required by law. 

        Section 6.8    Conduct of Business.    From the date of this Agreement through the
Closing, MWE Liberty shall operate the Business in the ordinary course and, without limiting the generality or effect of the foregoing, MWE Liberty shall use reasonable efforts to maintain the Assets,
comply with all applicable Laws, and preserve intact the Business and its relationships with customers, suppliers and others having business relationships with it, in each case in all material
respects. Without limiting the generality or effect of the foregoing, except as set forth on Schedule 3.4(b) or as contemplated in
Section 7.2(e), prior to the Closing, without the prior written consent of NGPMR, which consent shall not be unreasonably withheld, neither MWE Liberty nor the
Company shall (a) enter into any commercial contracts with an expected annual revenue in excess of ** (b) enter into any commercial, capital or construction contracts reasonably expected
to cause the Company to incur obligations in excess of ** or (c) make any capital expenditures in excess of ** in the aggregate. 

17

 
 
 

  ARTICLE 7
  CONDITIONS PRECEDENT  
    

        Section 7.1    Conditions to Each Party's Obligations.    The respective obligation of
each Party to effect the transactions contemplated hereby is subject to the satisfaction at or prior to the date hereof of the following conditions: 

        (a)   NGPMR
shall have made all filings required under the HSR Act and the applicable waiting periods shall have expired or been terminated without any conditions that would
require or result in either NGPMR or MWE Liberty holding separate or divesting assets or operations. 

        (b)   No
temporary restraining order, preliminary or permanent injunction or other order (whether temporary, preliminary or permanent) issued by any court or other
Governmental Authority of competent jurisdiction or other legal restraint or prohibition shall be in effect which prevents the consummation of the transactions contemplated by this Agreement. 

        (c)   No
legal proceeding shall be pending that involves any challenge to or seeking damages or other relief in connection with the transactions contemplated by this Agreement
or that may have the effect of preventing, delaying, making illegal, imposing limitations or conditions on or otherwise interfering with the transactions contemplated by this Agreement. 

        (d)   The
Credit Agreement shall be amended concurrent with the Closing to (i) exclude the Company as a Subsidiary and as a Loan Party (as such terms are defined in the
Credit Agreement), (ii) release the Assets to be contributed to the Company at Closing from any Liens (as such term is defined in the Credit Agreement) under the Credit Agreement and
(iii) permit MWE Liberty's initial contribution to, and future investments in, the Company. 

        (e)   (i)
The Company shall ** (as such term is defined in the **) under the ** and (ii) MWE Liberty shall provide a certificate to NGPMR, dated as of the Closing Date,
certifying that the condition specified in this Section 7.1(e) have been satisfied, together with supporting documentation that **. 

        Section 7.2    Conditions to NGPMR's Obligations.    The obligation of NGPMR to
consummate the transactions contemplated by this Agreement is subject to the satisfaction of the following conditions, any one or more of which may be waived in writing by NGPMR: 

        (a)    Representations, Warranties and Covenants of MWE Liberty.    (i) Each of the
representations and warranties of MWE Liberty made in this Agreement will be true and correct as of the date of this Agreement (except to the extent such representations and warranties speak to an
earlier date, in which case as of such earlier date) and as of the Closing (as if made anew at and as of the Closing, except to the extent such representations speak to an earlier date, in which case
as of such earlier date) except to the extent the failure of such representations and warranties to be true and correct as of the Closing Date has not had, and is not reasonably expected to have,
individually or in the aggregate, a Material Adverse Effect (provided that for purposes of determining whether the condition set forth in this sentence has been satisfied, all "Material Adverse
Effect" and other materiality qualifiers contained in the MWE Liberty's representations and warranties shall be disregarded), and (ii) MWE Liberty shall have performed or complied in all
material respects with all of the covenants and agreements required by this Agreement to be performed or complied with by MWE Liberty on or before the Closing; 

        (b)    No Material Adverse Effect.    Since the date of the Agreement, there shall not
have been any Material Adverse Effect with respect to MWE Liberty or the Assets; 

        (c)    Third Party Consents; Governmental Approvals.    The consents, authorizations,
approvals, exemptions and/or waivers listed on Schedule 7.2(c) shall have been received or obtained by MWE Liberty; 

18

 

        (d)    Purchase and Sale Agreement.    The closing contemplated by that certain Purchase
and Sale Agreement, dated as of **, between ** and MWE Liberty and/or the Company, shall have occurred; 

        (e)    ** Agreements.    The agreements between MWE Liberty and ** to (i) include
** from the **, (ii) provide for an ** to result in an ** and (iii) increase ** to **; and 

        (f)    Closing Documents.    MWE Liberty shall have delivered or caused to be delivered
all of the closing deliveries set forth in Section 2.4(b). 

        Section 7.3    Conditions to MWE Liberty's Obligations.    The obligation of MWE
Liberty to consummate the transactions contemplated by this Agreement is subject to the satisfaction of the following conditions, any one or more of which may be waived in writing by MWE Liberty: 

        (a)    Representations, Warranties and Covenants of NGPMR.    (i) Each of the
representations and warranties of NGPMR made in this Agreement will be true and correct as of the date of this Agreement (except to the extent such representations and warranties speak to an earlier
date, in which case as of such earlier date) and as of the Closing (as if made anew at and as of the Closing, except to the extent such representations and warranties speak to an earlier date, in
which case as of such earlier date) except to the extent the failure of such representations and warranties to be true and correct as of the Closing Date has not had, and is not reasonably expected to
have, individually or in the aggregate, a Material Adverse Effect (provided that for purposes of determining whether the condition set forth in this sentence has been satisfied, all "Material Adverse
Effect" and other materiality qualifiers contained in the NGPMR's representations and warranties shall be disregarded), and (ii) NGPMR shall have performed or complied in all material respects
with all of the covenants and agreements required by this Agreement to be performed or complied with by NGPMR on or before the Closing; and 

        (b)    Closing Documents.    MWE shall have delivered or caused to be delivered all of
the closing deliveries set forth in Section 2.4(a). 

 
 

  ARTICLE 8
  TERMINATION  
    

        Section 8.1    Termination.    At any time prior to the Closing, this Agreement may be
terminated and the transactions contemplated hereby abandoned: 

        (a)   by
the mutual consent of NGPMR and MWE Liberty as evidenced in writing signed by each of NGPMR and MWE Liberty; 

        (b)   by
NGPMR, if there has been a breach by MWE Liberty of any representation, warranty or covenant contained in this Agreement that has prevented the satisfaction of any
condition to the obligations of NGPMR at the Closing and, if such breach is of a character that it is capable of being cured, such breach has not been cured by MWE Liberty within thirty
(30) days after written notice thereof from NGPMR; provided that NGPMR is not then in material breach of the condition set forth in
Section 8.1(c); 

        (c)   by
MWE Liberty, if there has been a breach by NGPMR of any representation, warranty or covenant contained in this Agreement that has prevented the satisfaction of any
condition to the obligations of MWE Liberty at the Closing and, if such breach is of a character that it is capable of being cured, such breach has not been cured by NGPMR within thirty
(30) days after written notice thereof from MWE Liberty provided that MWE Liberty is not then in material breach of the condition set forth in
Section 8.1(b); 

        (d)   by
either NGPMR or MWE Liberty if any Governmental Authority having competent jurisdiction has issued a final, non-appealable order, decree, ruling or
injunction (other than a 

19

 

temporary
restraining order) or taken any other action permanently restraining, enjoining or otherwise prohibiting the transactions contemplated by this Agreement; or 

        (e)   by
either NGPMR or MWE Liberty, if the transactions contemplated hereby have not been consummated by March 13, 2009, provided
that neither NGPMR nor MWE Liberty will be entitled to
terminate this Agreement pursuant to this Section 8.1(e) if such Person's breach of this Agreement has prevented the consummation of the transactions contemplated
by this Agreement. 

        Section 8.2    Effect of Termination.    If this Agreement is terminated under
Section 8.1, all further obligations of the Parties under this Agreement will terminate without further liability or obligation of either Party to the other Parties hereunder;  provided, however,
nothing herein shall prejudice the ability of the non-breaching party from seeking damages from any other Party for any
actual fraud involving a knowing and intentional misrepresentation or omission of a material fact or willful or intentional breach of this Agreement, including attorneys' fees and the right to pursue
any remedy at law or in equity; provided further that if NGPMR terminates this Agreement as a result of a failure of a condition set forth in
Section 8.1(b) due to a material misrepresentation or inaccuracy of a representation or warranty by MWE Liberty made as of the date hereof, then MWE Liberty shall
** as set forth in **. The Confidentiality Agreement shall not be affected by a termination of this Agreement. Nothing in this Section 8.2 will relieve any Party of
their obligation to ** as set forth in **. 

 
 

  ARTICLE 9
  GENERAL PROVISIONS  
    

        Section 9.1    Effective Time.    If the transactions contemplated hereby are
consummated in accordance with the terms and conditions of this Agreement, the ownership of the Assets and the Assumed Liabilities shall be deemed transferred as of 11:59 p.m., Houston, Texas
time, on the Closing Date. 

        Section 9.2    Costs; Taxes.    The Company shall be responsible for recording and
filing documents associated with the transfer of the Assets to it and for all costs and fees associated therewith, including (i) filing the assignments with appropriate federal, state and local
Governmental Authorities as required by applicable Law and (ii) the payment of any and all stamp, documentary, real property transfer, sales, gross receipts, use or similar Taxes or assessments
(if any) arising out of the conveyance of the Assets and the assumption of the Assumed Liabilities as contemplated by this Agreement (collectively, the "Transfer
Taxes"). Each Party shall cooperate with the other in timely making all filings, returns, reports and forms as may be required in connection with the payment of the expenses,
fees and costs contemplated by the previous sentence, including delivering all instruments and certificates as are reasonably necessary to minimize such expenses, fees and costs and to enable the
other Party to timely comply with the filing of any tax return that relates to such expenses, fees and costs. 

        Section 9.3    Notices.    Any notice, demand or communication required or permitted
under this Agreement shall be in writing and delivered personally or by reputable overnight delivery service or 

20

 

other
courier, and shall be deemed to have been duly given as of the date and time reflected on the delivery receipt, addressed as follows: 

If
to the Company: 

MarkWest
Liberty Midstream & Resources, L.L.C.

1515 Arapahoe Street

Tower 2, Suite 700

Denver, Colorado 80202-2126

Attention: Senior Vice President and Chief Operations Officer 

and

MarkWest
Liberty Midstream & Resources, L.L.C.

1515 Arapahoe Street

Tower 2, Suite 700

Denver, Colorado 80202-2126

Attention: General Counsel 

If
to MWE Liberty: 

MarkWest
Liberty Gas Gathering, L.L.C.

1515 Arapahoe Street

Tower 2, Suite 700

Denver, Colorado 80202-2126

Attention: Senior Vice President and Chief Operations Officer 

and 

MarkWest
Liberty Gas Gathering, L.L.C.

1515 Arapahoe Street

Tower 2, Suite 700

Denver, Colorado 80202-2126

Attention: General Counsel 

If
to NGPMR: 

M&R
MWE Liberty, LLC

1401 McKinney, Suite 1025

Houston, Texas 77010

Attention: ** 

with
a copy to: 

Locke
Lord Bissell & Liddell, LLP

600 Travis Street, Suite 3400

Houston, Texas 77002

Fax (713) 229-2518

Attention: ** 

A
Party may change its address for the purposes of notices hereunder by giving notice to the other Party specifying such changed address in the manner specified in this
Section 9.3. 

        Section 9.4    Binding Effect.    This Agreement will be binding upon, and will inure
to the benefit of, the Parties and their respective successors, permitted assigns and legal representatives. 

        Section 9.5    No Third Party Rights.    The provisions of this Agreement are intended
to bind the Parties as to each other and are not intended to and do not create rights in any other Person or confer 

21

 

upon
any other Person (other than the express beneficiaries of the indemnity provisions contained in Sections 5.2, 5.3 and 5.4) any benefits, rights or remedies and
no Person is or is intended to be a third party beneficiary of any of the provisions of this Agreement. 

        Section 9.6    No Waiver.    No waiver or consent, express or implied, by any Party to
or of any breach or default by any Person in the performance by such Person of its obligations hereunder shall be deemed or construed to be a consent or waiver to or of any other breach or default in
the performance by such Person of the same or any other obligations of such Person hereunder. Failure on the part of a Party to complain of any act of any Person or to declare any Person in default,
irrespective of how long such failure continues, shall not constitute a waiver by such Party of its rights hereunder until the applicable statute of limitations period has run. 

        Section 9.7    Applicable Law.    THIS AGREEMENT AND THE RIGHTS OF THE PARTIES
HEREUNDER SHALL BE INTERPRETED IN ACCORDANCE WITH THE LAWS OF THE STATE OF DELAWARE AND ALL RIGHTS AND REMEDIES SHALL BE GOVERNED BY SUCH LAWS WITHOUT REGARD TO PRINCIPLES OF CONFLICT OF LAWS;  PROVIDED, HOWEVER, THAT MATTERS CONCERNING TITLE TO THE TRANSFERRED ASSETS SHALL BE GOVERNED AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE
JURISDICTION WHERE SUCH TRANSFERRED ASSETS ARE LOCATED. THE PARTIES FURTHER AGREE THAT ANY LEGAL ACTION OR PROCEEDING WITH RESPECT TO THIS AGREEMENT OR ANY DOCUMENT RELATING HERETO MAY BE BROUGHT ONLY
IN A FEDERAL OR STATE COURT OF COMPETENT JURISDICTION IN HOUSTON, TEXAS. EACH PARTY HEREBY IRREVOCABLY WAIVES ANY OBJECTION, INCLUDING, BUT NOT LIMITED TO, ANY OBJECTION TO THE LAYING OF VENUE OR
BASED ON THE GROUNDS OF FORUM NON-CONVENIENCE, WHICH IT MAY NOW OR HEREAFTER HAVE TO THE BRINGING OF SUCH ACTION OR PROCEEDING IN ANY SUCH RESPECTIVE JURISDICTION. 

        Section 9.8    Severability.    If any of the provisions of this Agreement are held by
any court of competent jurisdiction to contravene, or to be invalid under, the laws of any political body having jurisdiction over the subject matter hereof, such contravention or invalidity shall not
invalidate the entire Agreement. Instead, this Agreement shall be construed as if it did not contain the particular provision or provisions held to be invalid and an equitable adjustment shall be made
and necessary provision added so as to give effect to the intention of the Parties as expressed in this Agreement at the time of execution of this Agreement. 

        Section 9.9    Amendment or Modification.    This Agreement may be amended, modified or
supplemented from time to time only by a written agreement executed by all the Parties. 

        Section 9.10    Assignment; Deed; Bill of Sale.    No Party shall have the right to
assign its right or obligations under this Agreement without the prior written consent of the other Parties. To the extent required and permitted by applicable Law, this Agreement shall also
constitute a "deed," "bill of sale" or "assignment" of the assets and interests referenced herein. 

        Section 9.11    Conspicuousness of Provisions.    THE PARTIES ACKNOWLEDGE AND AGREE
THAT THE PROVISIONS CONTAINED IN THIS AGREEMENT THAT ARE IN CAPITALIZED LETTERS SATISFY THE REQUIREMENT OF THE "EXPRESS NEGLIGENCE RULE" AND ANY OTHER REQUIREMENT AT LAW OR IN EQUITY THAT PROVISIONS
CONTAINED IN A CONTRACT BE CONSPICUOUSLY MARKED OR HIGHLIGHTED. 

        Section 9.12    Counterparts.    This Agreement may be executed in any number of
counterparts with the same effect as if all Parties had signed the same document. All counterparts shall be construed together and shall constitute one and the same instrument. Execution and delivery
of this Agreement 

22

 

by
exchange of facsimile or other electronically transmitted counterparts bearing the signature of a Party shall be equally as effective as delivery of a manually executed counterpart by such Party. 

        Section 9.13    No Recourse Against Officers or Directors.    For the avoidance of
doubt, the provisions of this Agreement shall not give rise to any right of recourse against any officer, director or manager of any Party. 

        Section 9.14    Entire Agreement; Supersedure.    This Agreement and the instruments
referenced herein supersede all previous understandings or agreements among the Parties, whether oral or written, with respect to their subject matter. This Agreement and such instruments contain the
entire understanding of the Parties with respect to the subject matter hereof and thereof. No understanding, representation, promise or agreement, whether oral or written, is intended to be or shall
be included in or form part of this Agreement unless it is contained in a written amendment hereto executed by the Parties hereto after the date of this Agreement. 

[Signature
Page Follows] 

23

 

 
        IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of the date first written above. 

					
	 	 	 MARKWEST LIBERTY GAS GATHERING, L.L.C.
	

 	
 	
By:	
 	
/s/ Frank M. Semple

  Frank M. Semple

President and Chief Executive Officer
	

 	
 	
 MARKWEST LIBERTY MIDSTREAM & RESOURCES, L.L.C.
	

 	
 	
By:	
 	
/s/ Frank M. Semple

  Frank M. Semple

President and Chief Executive Officer
	

 	
 	
 M&R MWE LIBERTY, LLC
	

 	
 	
By:	
 	
/s/ **

 
	 	 	Name:	 	**
	 	 	Title:	 	Managing Partner & Chief Executive Officer

Signature Page 1

 

 
 

  EXHIBIT A    
    
    DEFINED TERMS    
    

"Act" means the Delaware Limited Liability Company Act, 6 Del.C. §§ 18-101 et
seq., as it may be amended from time to time, and any successor thereto. 

"Affiliate" means with respect to a Person, any other Person that, directly or indirectly, Controls, is Controlled by, or is under Common Control with,
the specified Person. 

"Agreement" means this Contribution Agreement, as it may be amended, supplemented or modified from time to time. 

"Area of Mutual Interest" has the meaning ascribed to such term in the Company Operating Agreement. 

"Assets" shall have the meaning set forth in Section 2.1(b). 

"Assignment and Assumption" shall have the meaning set forth in Section 2.4(b)(v). 

"Assumed Liabilities" shall have the meaning set forth in Section 2.2. 

"Base Cap" means **. 

"Basket Amount" means **. 

"Benefit Plans" shall have the meaning set forth in Section 3.15(b). 

"Business" shall have the meaning set forth in the recitals. 

"Business Day" means any day that is not a Saturday, Sunday or other day on which commercial banks are required or authorized by law to be closed in the
State of Texas or the State of Colorado. 

"CERCLA" means the Comprehensive Environmental Response, Compensation and Liability Act, 42 U.S.C. §9601 et seq., as amended. 

"Class A Interests" has the meaning ascribed to such term in the Company Operating Agreement. 

"Class A Member" has the meaning ascribed to such term in the Company Operating Agreement. 

"Class A Percentage Interests" has the meaning ascribed to such term in the Company Operating Agreement. 

"Class B Interests" has the meaning ascribed to such term in the Company Operating Agreement. 

"Class B Member" has the meaning ascribed to such term in the Company Operating Agreement. 

"Claim Notice" shall have the meaning set forth in Section 5.6(a). 

"Closing" shall have the meaning set forth in Section 2.3. 

"Closing Date" shall have the meaning set forth in Section 2.3. 

"Code" means the Internal Revenue Code of 1986, as amended. 

"Company" shall have the meaning set forth in the preamble. 

**
means an amount equal to the lesser of (a) ** or (b) the ** at the time of an indemnification claim pursuant to **, in each case, less any amount paid by ** in respect of
indemnification claims under this Agreement. 

"Company Operating Agreement" shall have the meaning set forth in the recitals. 

"Confidentiality Agreement" shall mean that certain Amended and Restated Confidentiality Agreement, dated as of **, by and between MarkWest Energy
Partners, L.P. and NGP Midstream & Resources, L.P. 

A-1

 

"Consents" shall have the meaning set forth in Section 6.5. 

"Control," including the correlative terms "Controlling," "Controlled by" and "under Common Control with" means possession, directly or indirectly
(through one or more intermediaries), of the power to direct or cause the direction of the management or policies (whether through ownership of securities or any partnership or other ownership
interest, by contract or otherwise) of a Person. For the purposes of this definition, ownership of more than 50% of the voting interests of any entity shall be conclusive evidence that Control exists. 

"Credit Agreement" means that certain Credit Agreement, dated as of February 20, 2008, among MWE, certain subsidiary guarantors, Royal Bank of
Canada, as Administrative Agent and Collateral Agent, and the other lenders party thereto. 

"Disclosed Liabilities" means any and all liabilities of MWE Liberty and/or the Company (i) arising from or relating to matters set forth on the
disclosure schedules of MWE Liberty or (ii) set forth on the Trial Balance or arising after the date of the Trial Balance in the ordinary course of business. 

"DOJ" shall have the meaning set forth in Section 6.1(a). 

"Effective Date" means 12:01 a.m. on January 1, 2009. 

"Environmental Claim" means any Proceeding or Loss resulting from or arising out of: (i) violation of or liability (including STRICT LIABILITY)
under any Environmental Law or Environmental Permit; (ii) the performance of an Environmental Response; (iii) unlawful exposure to Hazardous Substances; or (iv) the Release of any
Hazardous Substances. 

"Environmental Laws" means any and all applicable laws (including common law), rules, ordinances, codes, decrees, judgments, directives, judicial or
administrative orders or regulations of any Governmental Authority having jurisdiction over MWE Liberty or its Assets pertaining to prevention of pollution, protection of the environment, remediation
of contamination, or workplace health and safety, including CERCLA; the Resource Conservation and Recovery Act, 42 U.S.C. § 6901 et seq.; the
Federal Water Pollution Control Act, 33 U.S.C. § 1251 et seq.; the Clean Air Act, 42 U.S.C. § 7401
et seq.; the Hazardous Materials Transportation Act, 49 U.S.C. § 5101 et seq.; the Toxic Substances Control
Act, 15 U.S.C. §§ 2601 through 2629; the Oil Pollution Act, 33 U.S.C. § 2701 et seq.; the Emergency Planning and
Community Right-to-Know Act, 42 U.S.C. § 11001 et seq.; the Safe Drinking Water Act, 42 U.S.C.
§§ 300f through 300j; the Occupational Safety and Health Act, 29 U.S.C. § 651 et seq.; each as amended, and all
similar laws, rules and regulations of any Governmental Authority having jurisdiction over MWE Liberty or its Assets. 

"Environmental Permits" means Permits required under Environmental Law. 

"Environmental Response" means any action required under Environmental Law: (i) to prevent, respond to, remove, remediate, abate, investigate or
monitor the release or threatened release of Hazardous Substances at, on, in, about, under, within or near the air, soil, surface water, groundwater, or other environmental media; or (ii) to
correct a violation under Environmental Law. 

"ERISA" shall have the meaning set forth in Section 3.15(b). 

"ERISA Affiliate" means any entity (whether or not incorporated) which is a member of a controlled group including MWE Liberty or the Company or which
is under Common Control with MWE Liberty or the Company within the meaning of Sections 414(b), (c), (m) or (o) of the Code. 

"Excluded Assets" shall have the meaning set forth in Section 2.1(b)(ii). 

"FTC" shall have the meaning set forth in Section 6.1(a). 

"GAAP" means generally accepted accounting principles in the United States. 

A-2

 

"Governmental Authority" means any governmental, quasi-governmental, state, county, city or other political subdivision of the United States or any
other country, or any agency, court or instrumentality, foreign or domestic, or statutory or regulatory body thereof. 

"Hazardous Substances" means and includes each substance, waste or material regulated, defined, designated or classified as a hazardous waste, hazardous
substance, hazardous material, pollutant, contaminant or toxic (or words of similar import) substance under any Environmental Law and any petroleum or petroleum products that have been Released into
the environment, radioactive materials, asbestos, urea formaldehyde foam insulation, polychlorinated biphenyls and naturally occurring radioactive material. 

"Holding Period" means, for any particular Non-Assigned Asset, the period beginning on the Closing Date and ending on the earlier of
(i) the date upon which the contract or agreement for which the Consent was not obtained expires, or (ii) the date upon which such Consent or an alternative arrangement is obtained on
terms that are substantially similar in operational and economic effects as would have been achieved if the Non-Assigned Asset had been included within the Assets. 

"HSR Act" shall have the meaning set forth in Section 6.1(a). 

"Indebtedness" of any Person means any obligations of such Person: (a) for borrowed money, (b) evidenced by notes, bonds, indentures or
similar instruments, (c) for the deferred purchase price of goods and services (other than trade payables incurred in the ordinary course of business), (d) under capital leases or
(e) in the nature of guarantees of the obligations described in clauses (a) through (d) above of any other Person. 

"Indemnified Party" shall have the meaning set forth in Section 5.6(a). 

"Indemnifying Party" shall have the meaning set forth in Section 5.6(a). 

"Indentures" means (a) that certain Indenture, dated as of April 15, 2008, by and among MWE, MarkWest Energy Finance Corporation, a
Delaware corporation, the Subsidiary Guarantors (as defined therein), and Wells Fargo Bank, National Association, a national banking association, as trustee, (b) that certain Indenture, dated
as of July 6, 2006, by and among MWE, MarkWest Energy Finance Corporation, a Delaware corporation, the Subsidiary Guarantors (as defined therein), and Wells Fargo Bank, National Association, a
national banking association, as trustee, as amended and supplemented, and (c) that certain Indenture, dated as of October 25, 2004, by and among MWE, MarkWest Energy Finance
Corporation, a Delaware corporation, the Subsidiary Guarantors (as defined therein), and Wells Fargo Bank, National Association, a national banking association, as trustee, as amended and
supplemented. 

"Initial Budget" shall have the meaning ascribed to such term in the Company Operating Agreement. 

"Intellectual Property" means intellectual property rights, statutory or common Law, worldwide, including (a) trademarks, service marks, trade
dress, slogans, logos and all goodwill associated therewith, and any applications or registrations for any of the foregoing; (b) copyrights and any applications or registrations for any of the
foregoing; and (c) patents, all confidential know-how, trade secrets and similar proprietary rights in confidential inventions, discoveries, improvements, processes, techniques,
devices, methods, patterns, formulae, specifications, and lists of suppliers, vendors, customers, and distributors. 

"Investment Balance" shall have the meaning ascribed to such term in the Company Operating Agreement. 

"Knowledge" means the actual knowledge of the Persons listed on Schedule 1.1. 

A-3

 

"Law" means any law, statute, code, ordinance, order, rule, rules of common law, regulation, judgment, decree, injunction, franchise, permit,
certificate, license, authorization, or other directional requirement of any Governmental Authority. 

"Losses" shall have the meaning set forth in Section 5.2. 

"Material Adverse Effect" means any effect, event, development or change, (a) which individually or in the aggregate with all effects, events,
developments or changes is or is reasonably likely to become materially adverse to the business, assets, liabilities, properties, results of operations or financial condition of the Person, taken as a
whole, or (b) prevents or has an adverse effect on the ability of the Person to execute and perform their obligations under this Agreement or the other Transaction Documents or to consummate
the transactions contemplated hereby and thereby in accordance with the terms hereof and thereof, excluding any such result or consequence resulting from or related to (i) changes in general
economic, political or business conditions which affect the Person, except any such changes that affect the Person in a disproportionate manner compared to similarly situated participants in the
industries in which the Person operates; (ii) conditions affecting the oil and gas industry or oil and gas services industry generally except any such changes that affect the Person in a
disproportionate manner compared to similarly situated participants in the industries in which the Person operates; (iii) any change in law or in accounting rules except any such change that
affects the Person in a disproportionate manner compared to similarly situated participants in the industries in which the Person operates; or (iv) conditions or effects that have been
demonstrated by the Person as resulting from the announcement of the existence of this Agreement. 

"Material Contracts" shall mean all contracts, agreements, personal property leases, commitments, understandings or instruments of MWE Liberty or by
which MWE Liberty is bound that (a) is reasonably expected to (i) result in expenditures or liabilities in excess of ** or (ii) generate annual revenues in excess of **,
(b) contains any provision or covenant, which after the Closing will apply to the Business, or the Company, prohibiting or materially restricting MWE Liberty from engaging in any lawful
business activity or competing with any person or entity within the Area of Mutual Interest (as such term is defined in the Company Operating Agreement), (c) relates to Indebtedness of MWE
Liberty or (d) is in respect of any partnership, joint venture or other similar agreement or arrangement or otherwise relates to the joint ownership or operation of the assets owned by MWE
Liberty. 

"Members" shall have the meaning set forth in the recitals. 

"Miscellaneous Consents" means (a) all Consents that are not set forth on Schedule 7.2(c) and which relate to
interests in real property, including, without limitation, leases, rights-of-way, easements and other property use agreements and (b) Permits or Environmental Permits
issued by Governmental Authorities which are required in connection with the ownership or operation of the Assets **, and which Consents shall include any requirements of the applicable Governmental
Authorities requiring the reissuance of any such Permits or Environmental Permits in connection with the Closing and by the Transaction Documents. 

"MWE" means MarkWest Energy Partners, L.P., a Delaware limited partnership. 

"MWE **" means an amount equal to MWE Liberty's ** as of the Closing Date after giving effect to ** the Company contemplated hereby (prior to the **). 

"MWE Liberty" shall have the meaning set forth in the preamble. 

"MWE Liberty Covered Person" shall have the meaning set forth in Section 5.2. 

"NGPMR" shall have the meaning set forth in the preamble. 

"NGPMR Covered Persons" shall have the meaning set forth in Section 5.3. 

"Non-Assigned Asset" is defined in Section 6.5. 

A-4

 

"Organizational Documents" means the articles of incorporation, certificate of incorporation, certificate of formation, certificate of limited
partnership, bylaws, operating agreement, partnership agreement, stockholders' agreement and all other similar documents, instruments or certificates executed, adopted or filed in connection with the
creation, formation or organization of a Person, including any amendments thereto. 

"Parties" shall have the meaning set forth in the preamble. 

"Permits" shall have the meaning set forth in Section 3.13. 

"Permitted Liens" means (a) statutory liens for current Taxes applicable to the assets of MWE Liberty or assessments not yet delinquent or the
amount or validity of which is being contested in good faith and for which adequate reserves have been established in the Trial Balance; (b) mechanics', carriers', workers', repairers',
landlords', and other similar liens arising or incurred in the ordinary course of business MWE Liberty relating to obligations as to which there is no default on the part of MWE Liberty; and
(c) any liens, encumbrances, security interests, equities, charges or other restrictions with respect to assets of MWE Liberty, which, together with all other liens, encumbrances, security
interests, equities, charges or other restrictions, do not materially detract from the value of the Assets or materially interfere with the present use of the Assets or the conduct of the business of
MWE Liberty. 

"Person" means any natural person, corporation, limited partnership, general partnership, limited liability company, joint stock company, joint venture,
association, company, estate, trust, bank trust company, land trust, business trust, or other organization, whether or not a legal entity, custodian, trustee-executor, administrator, nominee or entity
in a representative capacity and any Governmental Authority. 

** 

"Pre-Closing Tax Period" shall have the meaning set forth in Section 6.3(b). 

"Proceeding" means any legal action, litigation, arbitration, hearing, written claim, legal proceeding, prosecution, investigation (for which
investigation a Governmental Authority has provided notice to MWE Liberty), or suit (whether civil, criminal or administrative) commenced, brought, conducted, or heard by or before, or otherwise
involving, any Governmental Authority or any arbitrator. 

"Release" means any depositing, spilling, leaking, pumping, pouring, placing, emitting, discarding, abandoning, emptying, discharging, migrating,
injecting, escaping, leaching, dumping, or disposing. 

"Rights-of-Way" shall have the meaning set forth in Section 3.8. 

"Services Agreement" shall have the meaning set forth in the recitals. 

"Specified Liabilities" means (a) the Disclosed Liabilities and (b) liabilities first arising after the Closing Date and relating to the
ownership, management or operation of the Assets under any contract, agreement, Permit or other instrument existing as of the Closing Date. "Specified Liabilities" shall not include those items listed
on Schedule 5.3(d) and Schedule 5.3(e). 

"Straddle Period" shall have the meaning set forth in Section 6.3(b). 

"Subsidiary" of any Person (the "Subject Person") means any Person, whether incorporated or
unincorporated, of which (a) at least 50% of the securities or ownership interests having by their terms ordinary voting power to elect a majority of the board of directors or other Persons
performing similar functions, (b) a general partner interest or (c) a managing member interest, is directly or indirectly owned or Controlled by the Subject Person or by one or more of
its respective Subsidiaries. 

"Survival Period" shall have the meaning set forth in Section 5.1(c). 

A-5

 

"Tax" or "Taxes" means (a) any taxes, assessments, fees, unclaimed property and escheat
obligations and other governmental charges imposed by any Governmental Authority, including, but not limited to, income, profits, gross receipts, net proceeds, alternative or add-on
minimum, ad valorem, value added, turnover, sales, use, property, personal property (tangible and intangible), environmental, stamp, leasing, lease, user, excise, duty, franchise, capital stock,
transfer, registration, license, withholding, social security (or similar), unemployment, disability, payroll, employment, social contributions, fuel, excess profits, occupational, premium, windfall
profit, severance, estimated, or other charge of any kind whatsoever, including any interest, penalty, or addition thereto, whether disputed or not; (b) any liability for the payment of any
amounts of the type described in clause (a) arising by reason of transferee or successor liability; and (c) any liability for the payment of any amounts of the type described in
clause (a) or (b) as a result of the operation of all or any express or implied obligation to indemnify any other Person. 

"Tax Benefit" means the reduction in the amount of Taxes that otherwise would have been paid by any Indemnified Party as a result of incurring any
Losses. 

"Tax Return" means any return, declaration, report, claim for refund, or information return or statement relating to Taxes, including any schedule or
attachment thereto, and including any amendment thereof. 

"Third Party Claim" shall have the meaning set forth in Section 5.6(a). 

"Transaction Documents" shall have the meaning set forth in Section 2.4. 

"Transactions" shall have the meaning set forth in Section 2.4. 

"Transfer Taxes" shall have the meaning set forth in Section 9.2. 

"Trial Balance" shall have the meaning set forth in Section 3.9. 

"Trial Balance Date" shall have the meaning set forth in Section 3.9. 

**
means that certain **, by and between MWE Liberty and **, as amended by Amendment No. 1 to **, by and between MWE Liberty and **. 

A-6

QuickLinks

CONTRIBUTION AGREEMENT BY AND AMONG MARKWEST LIBERTY GAS GATHERING, L.L.C., M&R MWE LIBERTY, LLC, AND MARKWEST LIBERTY MIDSTREAM & RESOURCES, L.L.C.

TABLE OF CONTENTS

CONTRIBUTION AGREEMENT

ARTICLE 1 DEFINITIONS; INTERPRETATION

ARTICLE 2 CONTRIBUTIONS, ASSUMED LIABILITIES AND CLOSING

ARTICLE 3 REPRESENTATIONS AND WARRANTIES OF MWE LIBERTY

ARTICLE 4 REPRESENTATIONS AND WARRANTIES OF NGPMR

ARTICLE 5 INDEMNIFICATION

ARTICLE 6 COVENANTS

ARTICLE 7 CONDITIONS PRECEDENT

ARTICLE 8 TERMINATION

ARTICLE 9 GENERAL PROVISIONS

EXHIBIT A DEFINED TERMS

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