Exhibit 4.1

MARKWEST ENERGY PARTNERS, L.P.,

MARKWEST ENERGY FINANCE CORPORATION, as Issuers,

THE SUBSIDIARIES NAMED HEREIN, as Subsidiary Guarantors

AND

WELLS FARGO BANK, NATIONAL ASSOCIATION, as Trustee

8¾% Series A Senior Notes due 2018

8¾% Series B Senior Notes due 2018

INDENTURE

Dated as of April 15, 2008

CROSS-REFERENCE TABLE*

N.A. means not applicable.

*This Cross-Reference Table is not part of the Indenture.

TABLE OF CONTENTS

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SCHEDULES, EXHIBITS AND ANNEXES

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THIS INDENTURE dated as of April 15, 2008 is among MarkWest Energy Partners, L.P., a Delaware limited partnership (the “Partnership”), MarkWest Energy Finance Corporation, a Delaware corporation (“MarkWest Finance” and, collectively with the Partnership, the “Issuers”), the Subsidiary Guarantors (as defined herein) listed on Schedule A hereto, and Wells Fargo Bank, National Association, a national banking association, as trustee (the “Trustee”).

The Issuers, the Subsidiary Guarantors, and the Trustee agree as follows for the benefit of each other and for the equal and ratable benefit of the Holders of the 8¾% Series A Senior Notes due 2018 (the “Series A Notes”) and the 8¾% Series B Senior Notes due 2018 (the “Exchange Notes” and, together with the Series A Notes, the “Notes”):

ARTICLE 1
DEFINITIONS AND INCORPORATION BY REFERENCE

Section 1.01.                  Definitions.

“ 144A Global Note ” means the Global Note in the form of Exhibit A hereto bearing the Global Note Legend and the Private Placement Legend and that has the “Schedule of Exchange of Interests in the Global Note” attached thereto and deposited with and registered in the name of the Depositary or its nominee that will be issued in a denomination equal to the outstanding principal amount of the Notes sold in reliance on Rule 144A, subject to adjustment as provided in Section 2.06 hereof.

“ Acquired Debt ” means, with respect to any specified Person: (1) Indebtedness of any other Person existing at the time such other Person is merged with or into or became a Subsidiary of such specified Person, whether or not such Indebtedness is incurred in connection with, or in contemplation of, such other Person merging with or into, or becoming a Subsidiary of, such specified Person, but excluding Indebtedness that is extinguished, retired or repaid in connection with such Person merging with or becoming a Subsidiary of such specified Person; and (2) Indebtedness secured by a Lien encumbering any asset acquired by such specified Person.

“ Additional Interest ” means all additional interest then owing pursuant to a Registration Rights Agreement.  Unless the context indicates otherwise, all references to “interest” in this Indenture or the Notes shall be deemed to include any Additional Interest.

“ Affiliate ” of any specified Person means any other Person directly or indirectly controlling or controlled by or under direct or indirect common control with such specified Person.  For purposes of this definition, “control,” as used with respect to any Person, shall mean the possession, directly or indirectly, of the power to direct or cause the direction of the management or policies of such Person, whether through the ownership of voting securities, by agreement or otherwise; provided that beneficial ownership of 10% or more of the Voting Stock of a specified Person shall be deemed to be control by the other Person; provided, further, that any third Person which also beneficially owns 10% or more of the Voting Stock of a specified Person shall not be deemed to be an Affiliate of either the specified Person or the other Person merely because of such common ownership in such specified Person.  For purposes of this definition, the terms “controlling,” “controlled by” and “under common control with” shall have

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correlative meanings.  Notwithstanding the preceding, the term “Affiliate” shall not include a Restricted Subsidiary of any specified Person.

“ Agent ” means any Registrar or Paying Agent.

“ Applicable Procedures ” means, with respect to any transfer or exchange of or for beneficial interests in any Global Note, the rules and procedures of the Depositary, Euroclear and Clearstream that apply to such transfer or exchange.

“ Asset Sale ” means:

(1)           the sale, lease, conveyance or other disposition of any assets, other than sales of inventory in the ordinary course of business; provided that the sale, lease, conveyance or other disposition of all or substantially all of the assets of the Partnership and its Restricted Subsidiaries taken as a whole will be governed by the provisions of Section 4.06 and/or the provisions of Article 5 hereof and not by the provisions of Section 4.07; and

(2)           the issuance of Equity Interests by any of the Partnership’s Restricted Subsidiaries or the sale by the Partnership or any of its Restricted Subsidiaries of Equity Interests in any of its Restricted Subsidiaries.

Notwithstanding the preceding, the following items shall not be deemed to be Asset Sales:

(1)           any single transaction or series of related transactions that: (a) involves assets having a fair market value of less than $5.0 million; or (b) results in net proceeds to the Partnership and its Restricted Subsidiaries of less than $5.0 million;

(2)           a transfer of assets between or among the Partnership and its Restricted Subsidiaries;

(3)           an issuance or sale of Equity Interests by a Restricted Subsidiary to the Partnership or to another Restricted Subsidiary of the Partnership;

(4)           a Restricted Payment that is permitted under Section 4.08 hereof or a Permitted Investment;

(5)           the sale or other disposition of cash or Cash Equivalents, Hedging Obligations or other financial instruments in the ordinary course of business;

(6)           any trade or exchange by the Partnership or any of its Restricted Subsidiaries of properties or assets for properties or assets owned or held by another Person, provided that the fair market value of the properties or assets traded or exchanged by the Partnership or such Restricted Subsidiary (together with any cash) is reasonably equivalent to the fair market value of the properties or assets (together with any cash) to be received by the Partnership or such Restricted Subsidiary, and provided further that any cash received must be applied in accordance with the provisions of Section 4.07 hereof;

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(7)           surrender or waiver of contract rights or the settlement, release or surrender of contract, tort or other claims of any kind;

(8)           the creation or perfection of a Lien that is not prohibited by Section 4.10;

(9)           dispositions in connection with Permitted Liens; and

(10)         the grant in the ordinary course of business of any non-exclusive license of patents, trademarks, registrations therefor and other similar intellectual property.

“ Attributable Debt ” in respect of a sale and lease-back transaction means, at the time of determination, the present value of the obligation of the lessee for net rental payments during the remaining term of the lease included in such sale and lease-back transaction, including any period for which such lease has been extended or may, at the option of the lessor, be extended.  Such present value shall be calculated using a discount rate equal to the rate of interest implicit in such transaction, determined in accordance with GAAP.

“ Available Cash ” has the meaning assigned to such term in the Partnership Agreement, as in effect on the Issue Date.

“ Bankruptcy Law ” means Title 11, U.S. Code or any similar federal or state law for the relief of debtors.

“ Beneficial Owner ” has the meaning assigned to such term in Rule 13d-3 and Rule 13d-5 under the Exchange Act, except that in calculating the beneficial ownership of any particular “person” (as that term is used in Section 13(d)(3) of the Exchange Act), such “person” will be deemed to have beneficial ownership of all securities that such “person” has the right to acquire by conversion or exercise of other securities, whether such right is currently exercisable or is exercisable only upon the occurrence of a subsequent condition.  The terms “Beneficially Owns” and “Beneficially Owned” have correlative meanings.

“ Board of Directors ” means, with respect to the Partnership, the Board of Directors of the General Partner, or any authorized committee of such Board of Directors, and with respect to MarkWest Finance or any other Subsidiary of the Partnership, the Board of Directors or managing members of such Person.

“ Board Resolution ” means a copy of a resolution certified by the Secretary or an Assistant Secretary of the applicable Person to have been duly adopted by the Board of Directors of such Person and to be in full force and effect on the date of such certification, and delivered to the Trustee.

“ Business Day ” means any day other than a Legal Holiday.

“ Capital Lease Obligation ” means, at the time any determination thereof is to be made, the amount of the liability in respect of a capital lease that would at that time be required to be capitalized on a balance sheet in accordance with GAAP.

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“ Cash Equivalents ” means:

(1)           United States dollars or, in an amount up to the amount necessary or appropriate to fund local operating expenses, other currencies;

(2)           securities issued or directly and fully guaranteed or insured by the United States government or any agency or instrumentality thereof (provided that the full faith and credit of the United States is pledged in support thereof) having maturities of not more than one year from the date of acquisition;

(3)           certificates of deposit, time deposits and eurodollar time deposits with maturities of one year or less from the date of acquisition, bankers’ acceptances with maturities not exceeding 365 days, demand and overnight bank deposits and other similar types of investments routinely offered by commercial banks, in each case, with any domestic commercial bank having a combined capital and surplus in excess of $500.0 million and a Thomson BankWatch Rating of “B” or better or any commercial bank of any other country that is a member of the Organization for Economic Cooperation and Development (“OECD”) and has total assets in excess of $500.0 million;

(4)           repurchase obligations with a term of not more than seven days for underlying securities of the types described in clauses (2) and (3) above entered into with any financial institution meeting the qualifications specified in clause (3) above;

(5)           commercial paper having one of the two highest ratings obtainable from Moody’s or Standard & Poor’s and in each case maturing within six months after the date of acquisition; and

(6)           money market funds at least 95% of the assets of which constitute Cash Equivalents of the kinds described in clauses (1) through (5) of this definition.

“ Certificated Note ” means a certificated Note registered in the name of the Holder thereof and issued in accordance with Section 2.06 hereof, in the form of Exhibit A hereto, except that such Note shall not bear the Global Note Legend, shall not have the phrase identified by footnote 3 thereto and shall not have the “Schedule of Exchanges of Interests in the Global Note” attached thereto.

“ Change of Control ” means the occurrence of any of the following:

(1)           the direct or indirect sale, lease, transfer, conveyance or other disposition (other than by way of merger or consolidation), in one or a series of related transactions, of all or substantially all of the properties or assets (including Equity Interests of the Restricted Subsidiaries) of the Partnership and its Restricted Subsidiaries taken as a whole, to any “person” (as that term is used in Section 13(d)(3) of the Exchange Act);

(2)           the adoption of a plan relating to the liquidation or dissolution of the Partnership or the removal of the General Partner by the limited partners of the Partnership;

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(3)           the consummation of any transaction (including, without limitation, any merger or consolidation) the result of which is that any “person” (as that term is used in Section 13(d)(3) of the Exchange Act), excluding the MarkWest Hydrocarbon Group, becomes the Beneficial Owner, directly or indirectly, of more than 50% of the Voting Stock of the General Partner, measured by voting power rather than number of shares;

(4)           the consummation of any transaction (including, without limitation, any merger or consolidation) the result of which is that any “person” (as that term is used in Section 13(d)(3) of the Exchange Act), excluding the Persons referred to in clause (1) of the definition of “MarkWest Hydrocarbon Group,” becomes the Beneficial Owner, directly or indirectly, of more than 50% of the Voting Stock of the Partnership, measured by voting power rather than number of shares, at a time when the Partnership still Beneficially Owns more than 50% of the Voting Stock of the General Partner, measured by voting power rather than number of shares; or

(5)           the first day on which a majority of the members of the Board of Directors of the General Partner are not Continuing Directors.

Notwithstanding the preceding, a conversion of the Partnership from a limited partnership to a corporation, limited liability company or other form of entity or an exchange of all of the outstanding limited partnership interests for capital stock in a corporation, for member interests in a limited liability company or for Equity Interests in such other form of entity shall not constitute a Change of Control, so long as following such conversion or exchange the MarkWest Hydrocarbon Group Beneficially Owns, directly or indirectly, in the aggregate more than 50% of the Voting Stock of such entity, or continues to Beneficially Own a sufficient percentage of Voting Stock of such entity to elect a majority of its directors, managers, trustees or other persons serving in a similar capacity for such entity.

“ Clearstream ” means Clearstream Banking, S.A. or any successor securities clearing agency.

“ Code ” means the Internal Revenue Code of 1986, as amended from time to time, and the rules and regulations thereunder, and any successor thereto.

“ Consolidated Cash Flow ” means, with respect to any Person for any period, the Consolidated Net Income of such Person for such period plus:

(1)           an amount equal to any net loss realized by such Person and its Restricted Subsidiaries in connection with an Asset Sale, to the extent such losses were deducted in computing such Consolidated Net Income; plus

(2)           provision for taxes based on income or profits of such Person and its Restricted Subsidiaries for such period, to the extent that such provision for taxes was deducted in computing such Consolidated Net Income; plus

(3)           the consolidated interest expense of such Person and its Restricted Subsidiaries for such period, whether paid or accrued (including, without limitation, amortization of debt issuance costs and original issue discount, non-cash interest

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payments, the interest component of any deferred payment obligations, the interest component of all payments associated with Capital Lease Obligations, imputed interest with respect to Attributable Debt, commissions, discounts and other fees and charges incurred in respect of letter of credit or bankers’ acceptance financings, and net of the effect of all payments made or received pursuant to interest-rate Hedging Obligations), to the extent that any such expense was deducted in computing such Consolidated Net Income; plus

(4)           depreciation, depletion and amortization (including amortization of goodwill and other intangibles but excluding amortization of prepaid cash expenses that were paid in a prior period) and other non-cash expenses (excluding any such non-cash expense to the extent that it represents an accrual of or reserve for cash expenses in any future period or amortization of a prepaid cash expense that was paid in a prior period) of such Person and its Restricted Subsidiaries for such period to the extent that such depreciation, depletion, amortization, impairment and other non-cash expenses were deducted in computing such Consolidated Net Income; plus

(5)           unrealized non-cash losses resulting from foreign currency balance sheet adjustments required by GAAP to the extent such losses are deducted in computing such Consolidated Net Income; plus

(6)           all extraordinary, unusual or non-recurring items of gain or loss, or revenue or expense; minus

(7)           non-cash items increasing such Consolidated Net Income for such period, other than items that were accrued in the ordinary course of business, in each case, on a consolidated basis and determined in accordance with GAAP.

Notwithstanding the preceding, the provision for taxes based on the income or profits of, and the depreciation, depletion and amortization and other non-cash charges of, a Restricted Subsidiary of the Partnership shall be added to Consolidated Net Income to compute Consolidated Cash Flow of the Partnership only to the extent that a corresponding amount would be permitted at the date of determination to be dividended or distributed to the Partnership by such Restricted Subsidiary without prior approval (that has not been obtained), pursuant to the terms of its charter and all agreements (other than this Indenture, the Notes or its Guarantee), instruments, judgments, decrees, orders, statutes, rules and governmental regulations applicable to that Restricted Subsidiary or its stockholders, partners or members.

“ Consolidated Net Income ” means, with respect to any specified Person for any period, the aggregate of the Net Income of such Person and its Restricted Subsidiaries for such period, on a consolidated basis, determined in accordance with GAAP; provided that:

(1)           Net Income (but not loss) of any Person that is not a Restricted Subsidiary or that is accounted for by the equity method of accounting will be included, but only to the extent of the amount of dividends or distributions paid in cash to the specified Person or a Restricted Subsidiary of the Person;

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(2)           the Net Income of any Restricted Subsidiary shall be excluded to the extent that the declaration or payment of dividends or similar distributions by that Restricted Subsidiary of that Net Income is not at the date of determination permitted without any prior governmental approval (that has not been obtained) or, directly or indirectly, by operation of the terms of its charter or any agreement (other than this Indenture, the Notes or its Guarantee), instrument, judgment, decree, order, statute, rule or governmental regulation applicable to that Restricted Subsidiary or its stockholders, partners or members;

(3)           the cumulative effect of a change in accounting principles shall be excluded;

(4)           unrealized losses and gains under derivative instruments included in the determination of Consolidated Net Income, including, without limitation, those resulting from the application of Statement of Financial Accounting Standards No. 133, shall be excluded; and

(5)           any nonrecurring charges relating to any premium or penalty paid, write off of deferred finance costs or other charges in connection with redeeming or retiring any Indebtedness prior to it Stated Maturity shall be excluded.

“ Consolidated Net Tangible Assets ” means, with respect to any Person at any date of determination, the aggregate amount of total assets included in such Person’s most recent quarterly or annual consolidated balance sheet prepared in accordance with GAAP less applicable reserves reflected in such balance sheet, after deducting the following amounts: (1) all current liabilities reflected in such balance sheet, and (2) all goodwill, trademarks, patents, unamortized debt discounts and expenses and other like intangibles reflected in such balance sheet.

“ Continuing Directors ” means, as of any date of determination, any member of the Board of Directors of the General Partner who (1) was a member of such Board of Directors on the Issue Date or (2) was nominated for election or elected to such Board of Directors with the approval of a majority of the Continuing Directors who were members of such Board at the time of such nomination or election.

“ Corporate Trust Office of the Trustee ” shall be at the address of the Trustee specified in Section 12.02 hereof or such other address as to which the Trustee may give notice to the Issuers.

“ Credit Agreement ” means that certain Credit Agreement, dated February 20, 2008, among the Partnership, the banks parties thereto and Royal Bank of Canada, as administrative agent, consisting of a revolver loan and a term loan, including any related notes, guarantees, collateral documents, instruments and agreements executed in connection therewith, and in each case as amended, restated, modified, renewed, refunded, replaced or refinanced in whole or in part from time to time.

“ Credit Facilities ” means, with respect to the Partnership, MarkWest Finance or any Restricted Subsidiary, one or more credit facilities or commercial paper facilities, including the Credit Agreement, providing for revolving credit loans, term loans, receivables financing

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(including through the sale of receivables to lenders or to special purpose entities formed to borrow from lenders against such receivables) or letters of credit, in each case, as amended, restated, modified, renewed, refunded, replaced or refinanced in whole or in part from time to time.

“ Default ” means any event that is or with the passage of time or the giving of notice or both would be, an Event of Default.

“ Depositary ” means, with respect to the Notes issuable or issued in whole or in part in global form, the Person specified in Section 2.03 hereof as the Depositary with respect to the Notes, and any and all successors thereto appointed as depositary hereunder and having become such pursuant to the applicable provision of this Indenture.

“ Disqualified Equity ” means any Equity Interest that, by its terms (or by the terms of any security into which it is convertible, or for which it is exchangeable, in each case at the option of the holder thereof), or upon the happening of any event, matures or is mandatorily redeemable, pursuant to a sinking fund obligation or otherwise, or redeemable at the option of the holder thereof, in whole or in part, on or prior to the date that is 91 days after the date on which the Notes mature.  Notwithstanding the preceding sentence, any Equity Interest that would constitute Disqualified Equity solely because the holders thereof have the right to require the Partnership or any of its Restricted Subsidiaries to repurchase such Equity Interests upon the occurrence of a change of control or an asset sale shall not constitute Disqualified Equity if the terms of such Equity Interests provide that the Partnership or Restricted Subsidiary may not repurchase or redeem any such Equity Interests pursuant to such provisions unless such repurchase or redemption is conditioned upon, and subject to, compliance with Section 4.08 hereof.

“ Distribution Compliance Period ” means the 40-day distribution compliance period as defined in Regulation S.

“ Equity Interests ” means:

(1)           in the case of a corporation, corporate stock;

(2)           in the case of an association or business entity, any and all shares, interests, participations, rights or other equivalents (however designated) of corporate stock;

(3)           in the case of a partnership or limited liability company, partnership or membership interests (whether general or limited);

(4)           any other interest or participation that confers on a Person the right to receive a share of the profits and losses of, or distributions of assets of, the issuing Person; and

(5)           all warrants, options or other rights to acquire any of the interests described in clauses (1) through (4) above (but excluding any debt security that is convertible into, or exchangeable for, any of the interests described in clauses (1) through (4) above).

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“ Equity Offering ” means any public or private sale for cash of Equity Interests of the Partnership (excluding sales made to any Restricted Subsidiary and excluding sales of Disqualified Equity) after the Issue Date; provided that a private placement of Equity Interests will not be deemed an Equity Offering unless net cash proceeds of at least $10.0 million are received.

“ Euroclear ” means the Euroclear System or any successor securities clearing agency.

“ Exchange Act ” means the Securities Exchange Act of 1934, as amended.

“ Exchange Notes ” means the 8¾% Series B Senior Notes due 2018, having terms substantially identical to the Series A Notes, offered to the Holders of the Series A Notes under an Exchange Offer Registration Statement.

“ Exchange Offer ” means an offer that may be made by the Issuers pursuant to a Registration Rights Agreement to the Holders of the Series A Notes to exchange their Series A Notes for a like aggregate principal amount of the Exchange Notes registered under the Securities Act.

“ Exchange Offer Registration Statement ” means a registration statement filed by the Issuers and the Subsidiary Guarantors with the SEC to register the Exchange Notes for issuance in an Exchange Offer.

“ Existing Indebtedness ” means the aggregate principal amount of Indebtedness of the Partnership and its Restricted Subsidiaries in existence on the Issue Date.

“ Fixed Charge Coverage Ratio ” means, with respect to any specified Person for any four-quarter reference period, the ratio of the Consolidated Cash Flow of such Person for such period to the Fixed Charges of such Person for such period.  In the event that the specified Person or any of its Restricted Subsidiaries incurs, assumes, guarantees, repays or redeems any Indebtedness (other than revolving credit borrowings not constituting a permanent commitment reduction) or issues or redeems Disqualified Equity subsequent to the commencement of the period for which the Fixed Charge Coverage Ratio is being calculated but prior to the date on which the event for which the calculation of the Fixed Charge Coverage Ratio is made (the “Calculation Date”), then the Fixed Charge Coverage Ratio shall be calculated giving pro forma effect to such incurrence, assumption, guarantee, repayment or redemption of Indebtedness, or such issuance or redemption of Disqualified Equity, and the application of the net proceeds thereof as if the same had occurred at the beginning of the applicable four-quarter reference period.

In addition, for purposes of calculating the Fixed Charge Coverage Ratio:

(1)           acquisitions that have been made by the specified Person or any of its Restricted Subsidiaries, including through mergers, consolidations or otherwise (including acquisitions of assets used in a Permitted Business), and including in each case any related financing transactions (including repayment of Indebtedness) during the four-quarter reference period or subsequent to such reference period and on or prior to the Calculation Date will be given pro forma effect as if they had occurred on the first day of

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the four-quarter reference period, including any Consolidated Cash Flow and any pro forma expense and cost reductions that have occurred or are reasonably expected to occur, in the reasonable judgment of the chief financial or accounting officer of the Partnership (regardless of whether those cost savings or operating improvements could then be reflected in pro forma financial statements in accordance with Regulation S-X promulgated under the Securities Act or any other regulation or policy of the SEC related thereto);

(2)           the Consolidated Cash Flow attributable to discontinued operations, as determined in accordance with GAAP, and operations or businesses disposed of prior to the Calculation Date, shall be excluded;

(3)           the Fixed Charges attributable to discontinued operations, as determined in accordance with GAAP, and operations or businesses disposed of prior to the Calculation Date, shall be excluded, but only to the extent that the obligations giving rise to such Fixed Charges will not be obligations of the specified Person or any of its Restricted Subsidiaries following the Calculation Date;

(4)           interest on outstanding Indebtedness of the specified Person or any of its Restricted Subsidiaries as of the last day of the four-quarter reference period shall be deemed to have accrued at a fixed rate per annum equal to the rate of interest on such Indebtedness in effect on such last day after giving effect to any Hedging Obligation then in effect; and

(5)           if interest on any Indebtedness incurred by the specified Person or any of its Restricted Subsidiaries on such date may optionally be determined at an interest rate based upon a factor of a prime or similar rate, a eurocurrency interbank offered rate or other rates, then the interest rate in effect on the last day of the four-quarter reference period will be deemed to have been in effect during such period.

“ Fixed Charges ” means, with respect to any Person for any period, the sum, without duplication, of:

(1)           the consolidated interest expense of such Person and its Restricted Subsidiaries for such period, whether paid or accrued, including, without limitation, amortization of debt issuance costs and original issue discount, non-cash interest payments, the interest component of any deferred payment obligations, the interest component of all payments associated with Capital Lease Obligations, imputed interest with respect to Attributable Debt, commissions, discounts, and other fees and charges incurred in respect of letter of credit or bankers’ acceptance financings, and net of the effect of all payments made or received pursuant to interest-rate Hedging Obligations; plus

(2)           the consolidated interest expense of such Person and its Restricted Subsidiaries that was capitalized during such period; plus

(3)           any interest expense on Indebtedness of another Person that is guaranteed by such Person or one of its Restricted Subsidiaries or secured by a Lien on assets of such

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Person or one of its Restricted Subsidiaries, whether or not such guarantee or Lien is called upon; plus

(4)           all dividend payments, whether paid or accrued and whether or not in cash, on any series of Disqualified Equity of such Person or any of its Restricted Subsidiaries, other than dividend payments on Equity Interests payable solely in Equity Interests of the Partnership (other than Disqualified Equity) or to the Partnership or a Restricted Subsidiary of the Partnership;

in each case, on a consolidated basis and in accordance with GAAP.

“ GAAP ” means generally accepted accounting principles in the United States, which are in effect from time to time.

“ General Partner ” means MarkWest Energy GP, L.L.C., a Delaware limited liability company, and its successors and permitted assigns as general partner of the Partnership.

“ Global Note Legend ” means the legend set forth in Section 2.06(g)(ii), which is required to be placed on all Global Notes issued under this Indenture.

“ Global Notes ” means, individually and collectively, each of the Restricted Global Notes and the Unrestricted Global Notes, in the form of Exhibit A hereto issued in accordance with Section 2.01, 2.06(b) or 2.06(f) hereof.

The term “ guarantee ” means a guarantee, other than by endorsement of negotiable instruments for collection in the ordinary course of business, direct or indirect, in any manner, including, without limitation, by way of a pledge of assets, or through letters of credit or reimbursement, “claw-back,” “make-well,” or “keep-well” agreements in respect thereof, of all or any part of any Indebtedness.  The term “guarantee” used as a verb has a corresponding meaning.  The term “guarantor” shall mean any Person providing a guarantee of any obligation.

“ Guarantee ” means, individually and collectively, the guarantees given by the Subsidiary Guarantors pursuant to Article 10 hereof, including a notation in the Notes substantially in the form attached hereto as Exhibit D.

“ Guarantee Obligations ” means, with respect to each Subsidiary Guarantor, the obligations of such Guarantor under Article 10.

“ Guarantor Subordinated Obligation ” means, with respect to a Subsidiary Guarantor, any Indebtedness or other Obligations of such Subsidiary Guarantor (whether outstanding on the Issue Date or thereafter incurred) which are expressly subordinate in right of payment to the Obligations of such Subsidiary Guarantor under its Guarantee pursuant to a written agreement.

“ Hedging Obligations ” means, with respect to any Person, the obligations of such Person under interest rate and commodity price swap agreements, interest rate and commodity price cap agreements, interest rate and commodity price collar agreements and foreign currency and commodity price exchange agreements, options or futures contracts or other similar agreements or arrangements or Hydrocarbon hedge contracts or Hydrocarbon forward sales contracts, in

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each case designed to protect such Person against fluctuations in interest rates, foreign exchange rates, or commodities prices.

“ Holder ” means the Person in whose name a Note is registered on the Registrar’s books.

“ Hydrocarbons ” means crude oil, natural gas, casinghead gas, drip gasoline, natural gasoline, condensate, distillate, liquid hydrocarbons, gaseous hydrocarbons and all constituents, elements or compounds thereof and products refined or processed therefrom.

“ IAI Global Note ” means the Global Note in the form of Exhibit A hereto bearing the Global Note Legend and the Private Placement Legend and that has the “Schedule of Exchange of Interests in the Global Note” attached thereto and deposited with and registered in the name of the Depositary or its nominee that will be issued in a denomination equal to the outstanding principal amount of the Notes transferred to Institutional Accredited Investors in accordance with 2.06(b)(iii)(C), subject to adjustment as provided in Section 2.06 hereof.

“ Indebtedness ” means, with respect to any specified Person, any indebtedness of such Person, whether or not contingent:

(1)           in respect of borrowed money;

(2)           evidenced by bonds, notes, debentures or similar instruments or letters of credit (or reimbursement agreements in respect thereof);

(3)           in respect of bankers’ acceptances;

(4)           representing Capital Lease Obligations;

(5)           representing all Attributable Debt of such Person in respect of any sale and lease-back transactions not involving a Capital Lease Obligation;

(6)           representing the balance deferred and unpaid of the purchase price of any property, except any such balance that constitutes an accrued expense or trade payable incurred in the ordinary course of business;

(7)           representing Disqualified Equity; or

(8)           representing any Hedging Obligations;

if and to the extent any of the preceding items (other than the item referred to in clause (5), letters of credit, Disqualified Equity and Hedging Obligations) would appear as a liability upon a balance sheet of the specified Person prepared in accordance with GAAP.  In addition, the term “Indebtedness” includes all Indebtedness of others secured by a Lien on any asset of the specified Person (whether or not such Indebtedness is assumed by the specified Person) and, to the extent not otherwise included, the guarantee by such Person of any Indebtedness of any other Person, provided that a guarantee otherwise permitted by this Indenture to be incurred by the Partnership or any of its Restricted Subsidiaries of Indebtedness incurred by the Partnership or a

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Restricted Subsidiary in compliance with the terms of this Indenture shall not constitute a separate incurrence of Indebtedness.

The amount of any Indebtedness outstanding as of any date shall be:

(1)           the accreted value thereof, in the case of any Indebtedness issued with original issue discount;

(2)           in the case of any Hedging Obligation, the termination value of the agreement or arrangement giving rise to such Hedging Obligation that would be payable by such Person at such date;

(3)           in the case of any letter of credit, the maximum potential liability thereunder; and

(4)           the principal amount thereof, together with any interest thereon that is more than 30 days past due, in the case of any other Indebtedness.

For purposes of clause (7) of the first paragraph of this definition, Disqualified Equity shall be valued at the maximum fixed redemption, repayment or repurchase price, which shall be calculated in accordance with the terms of such Disqualified Equity as if such Disqualified Equity were repurchased on any date on which Indebtedness shall be required to be determined pursuant to this Indenture; provided, however, that if such Disqualified Equity is not then permitted by its terms to be redeemed, repaid or repurchased, the redemption, repayment or repurchase price shall be the book value of such Disqualified Equity.  The amount of Indebtedness of any Person at any date shall be the outstanding balance at such date of all unconditional Obligations as described above and the maximum liability of any guarantees at such date; provided that for purposes of calculating the amount of any non-interest bearing or other discount security, such Indebtedness shall be deemed to be the principal amount thereof that would be shown on the balance sheet of the issuer thereof dated such date prepared in accordance with GAAP, but that such security shall be deemed to have been incurred only on the date of the original issuance thereof.

“ Indenture ” means this Indenture, as amended or supplemented from time to time.

“ Indirect Participant ” means a Person who holds a beneficial interest in a Global Note through a Participant.

“ Initial Purchasers ” means J.P. Morgan Securities Inc., RBC Capital Markets Corporation, Wachovia Capital Markets, LLC, Banc of America Securities LLC, Credit Suisse Securities (USA) LLC, Deutsche Bank Securities Inc., Fortis Securities LLC and SunTrust Capital Markets, Inc.

“ Institutional Accredited Investor ” means an institution that is an “accredited investor” as defined in Rule 501(a)(1), (2), (3) or (7) of the rules and regulations promulgated under the Securities Act.

“ Interest Payment Date ” means Stated Maturity of an installment of interest on the Notes.

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“ Investment Grade Rating ” means a rating equal to or higher than Baa3 (or the equivalent) by Moody’s and BBB- (or the equivalent) by Standard & Poor’s.

“ Investments ” means, with respect to any Person, all investments by such Person in other Persons (including Affiliates) in the forms of direct or indirect loans (including guarantees of Indebtedness or other Obligations), advances (other than advances to customers in the ordinary course of business that are recorded as accounts receivable on the balance sheet of the lender and commission, moving, travel and similar advances to officers and employees made in the ordinary course of business) or capital contributions, purchases or other acquisitions for consideration of Indebtedness, Equity Interests or other securities, together with all items that are or would be classified as investments on a balance sheet prepared in accordance with GAAP.  For purposes of the definition of “Unrestricted Subsidiary,” the definition of “Restricted Payment” and the covenant in Section 4.08 hereof, (1) the term “Investment” shall include the portion (proportionate to the Partnership’s Equity Interest in such Subsidiary) of the fair market value of the net assets of any Subsidiary of the Partnership or any of its Restricted Subsidiaries at the time that such Subsidiary is designated an Unrestricted Subsidiary; provided, however, that upon a redesignation of such Subsidiary as a Restricted Subsidiary, the Partnership or such Restricted Subsidiary shall be deemed to continue to have a permanent “Investment” in such Subsidiary at the time immediately before the effectiveness of such redesignation less the portion (proportionate to the Partnership’s or such Restricted Subsidiary’s Equity Interest in such Subsidiary) of the fair market value of the net assets of such Subsidiary at the time of such redesignation, and (2) any property transferred to or from an Unrestricted Subsidiary shall be valued at its fair market value at the time of such transfer, in each case as determined in good faith by the Board of Directors of the General Partner.  If the Partnership or any Restricted Subsidiary of the Partnership sells or otherwise disposes of any Equity Interests of any direct or indirect Restricted Subsidiary of the Partnership such that, after giving effect to any such sale or disposition, such Person is no longer a Restricted Subsidiary of the Partnership, the Partnership shall be deemed to have made an Investment on the date of any such sale or disposition equal to the fair market value of the Equity Interests of such Restricted Subsidiary not sold or disposed of in an amount determined as provided in the last paragraph of Section 4.08(b) hereof.

“ Issue Date ” means April 15, 2008.

“ Issuers ” means the Partnership and MarkWest Finance, collectively; “Issuer” means the Partnership or MarkWest Finance.

“ Joint Venture ” means any Person that is not a direct or indirect Subsidiary of the Partnership in which the Partnership or any of its Restricted Subsidiaries makes any Investment.

“ Legal Holiday ” means a Saturday, a Sunday or a day on which banking institutions in the City of Denver, Colorado, Dallas, Texas or New York, New York or at a place of payment are authorized by law, regulation or executive order to remain closed.  If a payment date is a Legal Holiday at a place of payment, payment may be made at that place on the next succeeding day that is not a Legal Holiday, and no interest shall accrue for the intervening period.

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“ Letter of Transmittal ” means the letter of transmittal to be prepared by the Issuers and sent to all Holders of the Series A Notes for use by such Holders in connection with an Exchange Offer.

“ Lien ” means, with respect to any asset, any mortgage, lien (statutory or otherwise), pledge, charge, security interest, hypothecation, assignment for security, claim, preference, priority or encumbrance of any kind in respect of such asset, whether or not filed, recorded or otherwise perfected under applicable law, including any conditional sale or other title retention agreement or any lease in the nature thereof, any option or other agreement to grant a security interest in and any filing of or agreement to give any financing statement under the Uniform Commercial Code (or equivalent statute) of any jurisdiction other than a precautionary financing statement respecting a lease not intended as a security agreement.

“ Make Whole Amount ” means, with respect to any Note at any redemption date, the excess, if any, of (1) an amount equal to the present value of (a) the redemption price of such Note at April 15, 2013 plus (b) the remaining scheduled interest payments on the Notes to be redeemed (subject to the right of Holders on the relevant record date to receive interest due on the relevant Interest Payment Date) to April 15, 2013 (other than interest accrued to the redemption date), computed using a discount rate equal to the Treasury Rate plus 50 basis points, over (2) the aggregate principal amount of the Notes to be redeemed.

“ MarkWest Finance ” means the Person named as such in the preamble of this Indenture under and until a successor replaces it pursuant to the applicable provision of this Indenture and thereafter means such successor.

“ MarkWest Hydrocarbon ” means MarkWest Hydrocarbon, Inc., a Delaware corporation, and its successors.

“ MarkWest Hydrocarbon Group ” means, collectively, (1) John M. Fox and any of his Affiliates, (2) MarkWest Hydrocarbon, (3) the Partnership and (4) each Person which is a direct or indirect Subsidiary of the Partnership.

“ Moody’s ” means Moody’s Investors Service, Inc. or any successor to the rating agency business thereof.

“ Net Income ” means, with respect to any Person, the consolidated net income (loss) of such Person and its Restricted Subsidiaries, determined in accordance with GAAP and before any reduction in respect of preferred stock dividends, excluding, however:

(1)                                  the aggregate gain (but not loss in excess of such aggregate gain), together with any related provision for taxes on such gain, realized in connection with:

(a)                       any Asset Sale; or

(b)                      the disposition of any securities by such Person or any of its Restricted Subsidiaries or the extinguishment of any Indebtedness of such Person or any of its Restricted Subsidiaries; and

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(2)           any extraordinary gain (but not loss), together with any related provision for taxes on such extraordinary gain (but not loss).

“ Net Proceeds ” means, with respect to any Asset Sale or sale of Equity Interests, the aggregate proceeds received by the Partnership or any of its Restricted Subsidiaries in cash or Cash Equivalents in respect of any Asset Sale or sale of Equity Interests (including, without limitation, any cash received upon the sale or other disposition of any non-cash consideration received in any such sale), net of, without duplication, (1) the direct costs relating to such Asset Sale or sale of Equity Interests, including, without limitation, brokerage commissions and legal, accounting and investment banking fees, sales commissions, recording fees, title transfer fees and any relocation expenses incurred as a result thereof, (2) taxes paid or payable as a result thereof, in each case after taking into account any available tax credits or deductions and any tax sharing arrangements and amounts required to be applied to the repayment of Indebtedness secured by a Lien on the asset or Equity Interests that were the subject of such Asset Sale or sale of Equity Interests, (3) all distributions and payments required to be made to minority interest holders in Restricted Subsidiaries as a result of such Asset Sale and (4) any amounts to be set aside in any reserve established in accordance with GAAP or any amount placed in escrow, in either case for adjustment in respect of the sale price of such asset or Equity Interests or for liabilities associated with such Asset Sale or sale of Equity Interests and retained by the Partnership or any of its Restricted Subsidiaries until such time as such reserve is reversed or such escrow arrangement is terminated, in which case Net Proceeds shall include only the amount of the reserve so reversed or the amount returned to the Partnership or its Restricted Subsidiaries from such escrow arrangement, as the case may be.

“ Non-Recourse Debt ” means Indebtedness as to which:

(1)           neither the Partnership nor any of its Restricted Subsidiaries (a) provides credit support of any kind (including any undertaking, agreement or instrument that would constitute Indebtedness), (b) is directly or indirectly liable as a guarantor or otherwise, or (c) constitutes the lender of such Indebtedness;

(2)           no default with respect to which (including any rights that the holders thereof may have to take enforcement action against an Unrestricted Subsidiary) would permit upon notice, lapse of time or both any holder of any other Indebtedness (other than the Notes) of the Partnership or any of its Restricted Subsidiaries to declare a default on such other Indebtedness or cause the payment thereof to be accelerated or payable prior to its Stated Maturity; and

(3)           the lenders have been notified in writing that they will not have any recourse to the stock or assets of the Partnership or any of its Restricted Subsidiaries, except as contemplated by clause (15) of the definition of “Permitted Liens.”

“ Non-U.S. Person ” means a person who is not a U.S. Person.

“ Note Custodian ” means the Trustee, as custodian with respect to the Notes in global form, or any successor entity thereto.

“ Notes ” has the meaning assigned to it in the preamble to this Indenture.

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“ Obligations ” means any principal, interest, penalties, fees, indemnifications, reimbursement obligations, damages and other liabilities payable under the documentation governing any Indebtedness.

“ Offering ” means the offering of the Series A Notes by the Issuers pursuant to the Offering Memorandum.

“ Offering Memorandum ” means the offering memorandum of the Issuers dated April 10, 2008 relating to the Offering.

“ Officer ” means, with respect to any Person, the Chairman of the Board, the Chief Executive Officer, the President, the Chief Operating Officer, the Chief Financial Officer, the Chief Accounting Officer, the Treasurer, any Assistant Treasurer, the Controller, the Secretary or any Vice-President of such Person (or, with respect to the Partnership, so long as it remains a partnership, the General Partner).

“ Officers’ Certificate ” means a certificate signed on behalf of each of the Partnership and MarkWest Finance by two of its Officers, one of whom must be the principal executive officer, the principal financial officer or the principal accounting officer of such Person, that meets the requirements of Section 12.05 hereof.

“ Operating Company ” means MarkWest Energy Operating Company, L.L.C., a Delaware limited liability company, and its successors.

“ Operating Surplus ” shall have the meaning assigned to such term in the Partnership Agreement, as in effect on the Issue Date.

“ Opinion of Counsel ” means an opinion from legal counsel who is reasonably acceptable to the Trustee, that meets the requirements of Section 12.05 hereof.  The counsel may be an employee of or counsel to the Partnership, MarkWest Finance or the General Partner (or any Subsidiary Guarantor, if applicable), any Subsidiary of the Partnership or the Trustee.

“ Participant ” means, with respect to DTC, Euroclear or Clearstream, a Person who has an account with DTC, Euroclear or Clearstream, respectively (and, with respect to DTC, shall include Euroclear and Clearstream).

“ Participating Broker-Dealer ” has the meaning set forth in the Registration Rights Agreement relating to the Series A Notes issued on the Issue Date.

“ Partnership ” means the Person named as such in the preamble of this Indenture unless and until a successor replaces it pursuant to the applicable provisions of this Indenture and thereafter means such successor.

“ Partnership Agreement ” means the Third Amended and Restated Agreement of Limited Partnership of MarkWest Energy Partners, L.P., dated as of February 21, 2008, as such may be amended, modified or supplemented from time to time.

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“ Permitted Business ” means either (1) gathering, transporting, treating, processing, marketing or otherwise handling Hydrocarbons, or activities or services reasonably related or ancillary thereto including entering into Hedging Obligations to support these businesses, or (2) any other business that generates gross income that constitutes “qualifying income” under Section 7704(d) of the Code.

“ Permitted Business Investments ” means Investments by the Partnership or any of its Restricted Subsidiaries in any Unrestricted Subsidiary of the Partnership or in any Joint Venture, provided that:

(1)           either (a) at the time of such Investment and immediately thereafter, the Partnership could incur $1.00 of additional Indebtedness under Section 4.09(a) or (b) such investment is made with the proceeds of Incremental Funds;

(2)           if such Unrestricted Subsidiary or Joint Venture has outstanding Indebtedness at the time of such Investment, either (a) all such Indebtedness is Non-Recourse Debt with respect to the Partnership and its Restricted Subsidiaries or (b) any other Indebtedness of such Unrestricted Subsidiary or Joint Venture could, at the time such Investment is made and, if later, at the time any such Indebtedness is incurred, be incurred by the Partnership and its Restricted Subsidiaries in accordance with the limitation on Indebtedness set forth in Section 4.09(a); and

(3)           such Unrestricted Subsidiary’s or Joint Venture’s activities are not outside the scope of the Permitted Business.

“ Permitted Investments ” means:

(4)           any Investment in, or that results in the creation of, any Restricted Subsidiary of the Partnership;

(5)           any Investment in the Partnership or in a Restricted Subsidiary of the Partnership (excluding redemptions, purchases, acquisitions or other retirements of Equity Interests in the Partnership);

(6)           any Investment in cash or Cash Equivalents;

(7)           any Investment by the Partnership or any Restricted Subsidiary of the Partnership in a Person if as a result of such Investment:

(a)                                  such Person becomes a Restricted Subsidiary of the Partnership; or

(b)                                 such Person is merged, consolidated or amalgamated with or into, or transfers or conveys substantially all of its assets to, or is liquidated into, the Partnership or a Restricted Subsidiary of the Partnership;

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(8)           any Investment made as a result of the receipt of consideration consisting of other than cash or Cash Equivalents from an Asset Sale that was made pursuant to and in compliance with Section 4.07;

(9)           any Investment in a Person solely in exchange for the issuance of Equity Interests (other than Disqualified Equity) of the Partnership;

(10)         Investments in stock, obligations or securities received in settlement of debts owing to the Partnership or any of its Restricted Subsidiaries as a result of bankruptcy or insolvency proceedings or upon the foreclosure, perfection or enforcement of any Lien in favor of the Partnership or any such Restricted Subsidiary, in each case as to debt owing to the Partnership or any such Restricted Subsidiary that arose in the ordinary course of business of the Partnership or any such Restricted Subsidiary;

(11)         any Investment in Hedging Obligations permitted to be incurred under Section 4.09 hereof; and

(12)         other Investments in any Person engaged in a Permitted Business (other than an Investment in an Unrestricted Subsidiary) having an aggregate fair market value (measured on the date each such Investment was made and without giving effect to subsequent changes in value), when taken together with all other Investments made pursuant to this clause (9) since the Issue Date and existing at the time of the Investment, which is the subject of the determination, was made, not to exceed the greater of (a) $25.0 million and (b) 2.50% of Consolidated Net Tangible Assets.

“ Permitted Liens ” means:

(1)           Liens securing Indebtedness under any of the Credit Facilities;

(2)           Liens in favor of the Partnership or any of its Restricted Subsidiaries;

(3)           any interest or title of a lessor in the property subject to a Capital Lease Obligation;

(4)           Liens on property of a Person existing at the time such Person is merged with or into or consolidated with the Partnership or any Restricted Subsidiary of the Partnership, provided that such Liens were in existence prior to, and were not obtained in contemplation of, such merger or consolidation and do not extend to any assets other than those of the Person merged into or consolidated with the Partnership or such Restricted Subsidiary; !

(5)           Liens on property existing at the time of acquisition thereof by the Partnership or any Restricted Subsidiary of the Partnership, provided that such Liens were in existence prior to, and were not obtained in contemplation of, such acquisition and relate solely to such property, accessions thereto and the proceeds thereof;

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(6)           Liens to secure the performance of tenders, bids, leases, statutory obligations, surety or appeal bonds, government contracts, performance bonds or other obligations of a like nature incurred in the ordinary course of business;

(7)           Liens on any property or asset acquired, constructed or improved by the Partnership or any Restricted Subsidiary, which (a) are in favor of the seller of such property or assets, in favor of the Person constructing or improving such asset or property, or in favor of the Person that provided the funding for the acquisition, construction or improvement of such asset or property, (b) are created within 360 days after the date of acquisition, construction or improvement, (c) secure the purchase price or construction or improvement cost, as the case may be, of such asset or property in an amount not to exceed the lesser of (i) the cost to the Partnership and its Restricted Subsidiaries of such acquisition, construction or improvement of such asset or property and (ii) 100% of the fair market value (as determined by the Board of Directors of the General Partner) of such acquisition, construction or improvement of such asset or property, and (d) are limited to the asset or property so acquired, constructed or improved (including proceeds thereof, accessions thereto and upgrades thereof);

(8)           Liens to secure performance of Hedging Obligations of the Partnership or any Restricted Subsidiary;

(9)           Liens existing on the Issue Date and Liens in connection with any extensions, refinancing, renewal, replacement or defeasance of any Indebtedness or other obligation secured thereby, provided that (a) the principal amount of the Indebtedness secured by such Lien is not increased and (b) no assets are encumbered by any such Lien other than the assets permitted to be encumbered immediately prior to such extension, refinancing, renewal, replacement or defeasance;

(10)         Liens on pipelines or pipeline facilities that arise by operation of law;

(11)         Liens arising under operating agreements, joint venture agreements, partnership agreements, oil and gas leases, farmout agreements, division orders, contracts for sale, transportation or exchange of oil and natural gas, unitization and pooling declarations and agreements, area of mutual interest agreements and other agreements arising in the ordinary course of the Partnership’s or any Restricted Subsidiary’s business that are customary in the Permitted Business;

(12)         Liens securing the Obligations of the Issuers under the Notes and this Indenture and of the Subsidiary Guarantors under the Guarantees;

(13)         Liens upon specific items of inventory or other goods and proceeds of any Person securing such Person’s Obligations in respect of bankers’ acceptances issued or created for the account of such Person to facilitate the purchase, shipment or storage of such inventory or other goods and permitted by Section 4.09 hereof;

(14)         Liens securing any Indebtedness equally and ratably with all Obligations due under the Notes or any Guarantee pursuant to a contractual covenant that limits liens in a manner substantially similar to Section 4.10 hereof;

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(15)         Liens on and pledges of the Equity Interests of any Unrestricted Subsidiaries or any Joint Venture owned by the Partnership or any Restricted Subsidiary of the Partnership to the extent securing Non-Recourse Debt or other Indebtedness of such Unrestricted Subsidiary or Joint Venture; and

(16)         Liens incurred in the ordinary course of business of the Partnership or any Restricted Subsidiary of the Partnership, provided that, after giving effect to any such incurrence, the aggregate principal amount of all Indebtedness then outstanding and secured by any Liens incurred pursuant to this clause (16) does not exceed the greater of $25.0 million or 2.5% of the Consolidated Net Tangible Assets of the Partnership.

After the termination of the covenants pursuant to Section 4.19 hereof, for purposes of complying with Section 4.10, the Liens described in clauses (1) and (16) of this definition of “Permitted Liens” shall be Permitted Liens only to the extent those Liens secure Indebtedness not exceeding, at the time of determination, 10% of the Consolidated Net Tangible Assets of the Partnership.  Once effective, this 10% limitation on Permitted Liens will continue to apply during any later period in which the Notes do not have an Investment Grade Rating from both Rating Agencies.

“ Permitted Refinancing Indebtedness ” means any Indebtedness of the Partnership or any of its Restricted Subsidiaries issued in exchange for, or the net proceeds of which are used to extend, refinance, renew, replace, defease or refund other Indebtedness of the Partnership or any of its Restricted Subsidiaries (other than intercompany Indebtedness); provided that:

(1)           the principal amount of such Permitted Refinancing Indebtedness does not exceed the principal amount of, plus accrued interest on, the Indebtedness so extended, refinanced, renewed, replaced, defeased or refunded (plus the amount of necessary fees and expenses incurred in connection therewith and any premiums paid on the Indebtedness so extended, refinanced, renewed, replaced, defeased or refunded);

(2)           such Permitted Refinancing Indebtedness has a final maturity date no earlier than the final maturity date of, and has a Weighted Average Life to Maturity equal to or greater than the Weighted Average Life to Maturity of, the Indebtedness being extended, refinanced, renewed, replaced, defeased or refunded;

(3)           if the Indebtedness being extended, refinanced, renewed, replaced, defeased or refunded is subordinated in right of payment to the Notes or the Guarantees, such Permitted Refinancing Indebtedness is subordinated in right of payment to, the Notes or the Guarantees, as the case may be, on terms at least as favorable to the Holders of Notes as those contained in the documentation governing the Indebtedness being extended, refinanced, renewed, replaced, defeased or refunded; and

(4)           such Indebtedness is not incurred by a Restricted Subsidiary if the Partnership is the obligor on the Indebtedness being extended, refinanced, renewed, replaced, defeased or refunded.

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“ Person ” means any individual, corporation, partnership, joint venture, association, joint-stock company, trust, unincorporated organization, limited liability company or government or any agency or political subdivision thereof or any other entity.

“ Private Placement Legend ” means the legend set forth in Section 2.06(g)(i) to be placed on all Notes issued under this Indenture except where otherwise permitted by the provisions of this Indenture.

“ QIB ” means a “qualified institutional buyer” as defined in Rule 144A.

“ Rating Agency ” means each of Standard & Poor’s and Moody’s, or if Standard & Poor’s or Moody’s or both shall not make a rating on the Notes publicly available, a nationally recognized statistical rating agency or agencies, as the case may be, selected by the Issuers (as certified by a resolution of the Board of Directors of the General Partner) which shall be substituted for Standard & Poor’s or Moody’s, or both, as the case may be.

“ Registrable Securities ” has the meaning set forth in the Registration Rights Agreement applicable to such Notes.

“ Registration Rights Agreement ” means (1) with respect to the Series A Notes issued on the Issue Date that certain agreement among the Issuers, the Subsidiary Guarantors and the Initial Purchasers requiring the Issuers and the Subsidiary Guarantors to file an Exchange Offer Registration Statement and a Shelf Registration Statement, a form of which is attached to this Indenture as Annex B hereto, and (2) any other registration rights agreement relating to any additional Notes issued by the Issuers after the Issue Date pursuant to Section 2.02.

“ Regulation S ” means Regulation S promulgated by the SEC under the Securities Act.

“ Regulation S Global Note ” means a Global Note in the form of Exhibit A hereto bearing the Global Note Legend and the Private Placement Legend and that has the “Schedule of Exchange of Interests in the Global Note” attached thereto and deposited with or on behalf of and registered in the name of the Depositary or its nominee, issued in a denomination equal to the outstanding principal amount of the Notes initially sold in reliance on Rule 903 of Regulation S, subject to adjustment as provided in Section 2.06 hereof.

“ Reporting Default ” means a Default described in Section 6.01(d) hereof.

“ Responsible Officer ,” when used with respect to the Trustee, means the officer in the Corporate Trust Department of the Trustee having direct responsibility for administration of this Indenture.

“ Restricted Certificated Note ” means a Certificated Note bearing the Private Placement Legend.

“ Restricted Global Note ” means a Global Note bearing the Private Placement Legend and that bears the Global Note Legend and that has the “Schedule of Exchanges of Interests in the Global Note” attached thereto.

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“ Restricted Investment ” means an Investment other than a Permitted Investment or a Permitted Business Investment.

“ Restricted Subsidiary ” of a Person means any Subsidiary of the referenced Person that is not an Unrestricted Subsidiary.  Notwithstanding anything in this Indenture to the contrary, each of MarkWest Finance and the Operating Company shall be a Restricted Subsidiary of the Partnership.

“ Rule 144 ” means Rule 144 promulgated by the SEC under the Securities Act.

“ Rule 144A ” means Rule 144A promulgated by the SEC under the Securities Act.

“ Rule 903 ” means Rule 903 of Regulation S promulgated by the SEC under the Securities Act.

“ Rule 904 ” means Rule 904 of Regulation S promulgated by the SEC under the Securities Act.

“ SEC ” means the Securities and Exchange Commission.

“ Securities Act ” means the Securities Act of 1933, as amended.

“ Series A Notes ” has the meaning set forth in the preamble of this Indenture.

“ Shelf Registration Statement ” means a shelf registration statement filed with the SEC by the Issuers and the Subsidiary Guarantors in accordance with the applicable Registration Rights Agreement to register resales of the Series A Notes or the Exchange Notes.

“ Significant Subsidiary ” means any Subsidiary that would be a “significant subsidiary” as defined in Article 1, Rule 1-02 of Regulation S-X, promulgated pursuant to the Securities Act and the Exchange Act, as such Regulation is in effect on the Issue Date.

“ Standard & Poor’s ” means Standard & Poor’s Ratings Services, a division of The McGraw-Hill Companies, Inc., or any successor to the rating agency business thereof.

“ Stated Maturity ” means, with respect to any installment of interest or principal on any series of Indebtedness, the date on which such payment of interest or principal was scheduled to be paid in the original documentation governing such Indebtedness, and shall not include any contingent Obligations to repay, redeem or repurchase any such interest or principal prior to the date originally scheduled for the payment thereof.

“ Subordinated Obligation ” means any Indebtedness of the Partnership or MarkWest Finance (whether outstanding on the Issue Date or thereafter incurred) that is subordinate or junior in right of payment to the Notes pursuant to a written agreement.

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“ Subsidiary ” means, with respect to any Person:

(1)           any corporation, association or other business entity (other than an entity referred to in clause (2) below) of which more than 50% of the total Voting Stock is at the time owned or controlled, directly or indirectly, by such Person or one or more of the other Subsidiaries of that Person (or a combination thereof); and

(2)           any partnership (whether general or limited), limited liability company or joint venture (a) the sole general partner or member of which is such Person or a Subsidiary of such Person, or (b) if there is more than a single general partner or member, either (i) the only general partners, members, managing general partners or managing members of which are such Person or one or more Subsidiaries of such Person (or any combination thereof) or (ii) such Person owns or controls, directly or indirectly, a majority of the outstanding general partner interests, member interests or other Voting Stock of such partnership, limited liability company or joint venture, respectively.

“ Subsidiary Guarantors ” means each of:

(1)           the Operating Company, MarkWest Hydrocarbon, the General Partner, Basin Pipeline L.L.C., MarkWest Blackhawk, L.L.C., MarkWest Energy Appalachia, L.L.C., MarkWest Energy East Texas Gas Company, L.L.C., MarkWest Gas Services, L.L.C., MarkWest Javelina Company, L.L.C., MarkWest Javelina Pipeline Company, L.L.C., MarkWest Michigan Pipeline Company, L.L.C., MarkWest New Mexico, L.L.C., MarkWest Pinnacle, L.L.C., MarkWest Pioneer, L.L.C., MarkWest Pipeline Company, L.L.C., MarkWest PNG Utility, L.L.C., MarkWest Power Tex, L.L.C., MarkWest Texas PNG Utility, L.L.C., MarkWest Oklahoma Gas Company, L.L.C., Mason Pipeline Limited Liability Company, Matrex, L.L.C., MarkWest Liberty Gas Gathering, L.L.C. and West Shore Processing Company, L.L.C.; and

(2)           any other Subsidiary of the Partnership that becomes a Subsidiary Guarantor in accordance with the provisions of Section 4.13 and Article 10 of this Indenture; and

(3)           their respective successors and assigns;

in each case until such Subsidiary Guarantor ceases to be such in accordance with this Indenture.  Notwithstanding anything in this Indenture to the contrary, MarkWest Finance shall not be a Subsidiary Guarantor.

“ Tax Payment ” means any payment of foreign, federal, state or local tax liabilities.

“ TIA ” means the Trust Indenture Act of 1939 (15 U.S.C. Sections 77aaa-77bbbb) as in effect on the date on which this Indenture is qualified under the TIA, except as provided in Section 9.03 hereof.

“ Treasury Rate ” means, at the time of computation, the yield to maturity of United States Treasury securities with a constant maturity (as compiled and published in the most recent Federal Reserve Statistical Release H.15(519) which has become publicly available at least two

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Business Days prior to the redemption date or, if such Statistical Release is no longer published, any publicly available source of similar market data) most nearly equal to the period from the redemption date to April 15 , 2013; provided, however , that if such period is not equal to the constant maturity of a United States Treasury security for which a weekly average yield is given, the Treasury Rate shall be obtained by linear interpolation (calculated to the nearest one-twelfth of a year) from the weekly average yields of United States Treasury securities for which such yields are given, except that if the period from the redemption date to April 15, 2013 is less than one year, the weekly average yield on actually traded United States Treasury securities adjusted to a constant maturity of one year shall be used.  The Treasury Rate shall be calculated on the third Business Day preceding the redemption date.  Any weekly average yields calculated by interpolation shall be rounded to the nearest 1/100th of 1%, with any figure of 1/200th of 1% or above being rounded upward.

“ Trustee ” means the party named as such in the preamble of this Indenture until a successor replaces it in accordance with the applicable provisions of this Indenture and thereafter means the successor serving hereunder.

“ U.S. Government Obligations ” means securities that are (1) direct Obligations of the United States of America for the payment of which its full faith and credit is pledged; (2) Obligations of a Person controlled or supervised by and acting as an agency or instrumentality of the United States of America the payment of which is unconditionally guaranteed as a full faith and credit obligation by the United States of America, which, in either case under clauses (1) or (2) above, are not callable or redeemable at the option of the issuers thereof; or (3) depository receipts issued by a bank or trust company as custodian with respect to any such U.S. Government Obligations or a specific payment of interest on or principal of any such U.S. Government Obligation held by such custodian for the account of the holder of a depository receipt, provided that (except as required by law) such custodian is not authorized to make any deduction from the amount payable to the holder of such depository receipt from any amount received by the custodian in respect of the U.S. Government Obligation evidenced by such depository receipt.

“ U.S. Person ” means a U.S. person as defined in Rule 902(k) of Regulation S promulgated by the SEC under the Securities Act.

“ Unrestricted Certificated Note ” means one or more Certificated Notes that do not bear and are not required to bear the Private Placement Legend.

“ Unrestricted Global Note ” means a permanent Global Note in the form of Exhibit A attached hereto that bears the Global Note Legend and that has the “Schedule of Exchanges of Interests in the Global Note” attached thereto, and that is deposited with or on behalf of and registered in the name of the Depositary, representing a series of Notes that do not bear the Private Placement Legend.

“ Unrestricted Subsidiary ” means any Subsidiary of the Partnership (other than MarkWest Finance or the Operating Company) that is designated by the Board of Directors of the General Partner as an Unrestricted Subsidiary pursuant to a Board Resolution, but only to the extent that such Subsidiary: (1) has no Indebtedness owing to any Person other than the Partnership or any

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of its Restricted Subsidiaries other than Non-Recourse Debt, except to the extent permitted by subclause (2)(b) of the definition of “Permitted Business Investments”; (2) is not a party to any agreement, contract, arrangement or understanding with the Partnership or any Restricted Subsidiary of the Partnership unless the terms of any such arrangement, contract, arrangement or understanding are no less favorable to the Partnership or such Restricted Subsidiary than those that might be obtained at the time from Persons who are not Affiliates of the Partnership; (3) is a Person with respect to which neither the Partnership nor any of its Restricted Subsidiaries has any direct or indirect obligation (a) to subscribe for additional Equity Interests or (b) to maintain or preserve such Person’s financial condition or to cause such Person to achieve any specified levels of operating results; and (4) has not guaranteed or otherwise directly or indirectly provided credit support for any Indebtedness of the Partnership or any of its Restricted Subsidiaries.  Notwithstanding anything in this Indenture to the contrary, neither MarkWest Finance nor the Operating Company shall be designated as an Unrestricted Subsidiary.

Any designation of a Subsidiary of the Partnership as an Unrestricted Subsidiary shall be evidenced to the Trustee by filing with the Trustee a Board Resolution of the General Partner giving effect to such designation and an Officers’ Certificate certifying that such designation complied with the preceding conditions and was permitted by Section 4.08 hereof.  If, at any time, any Unrestricted Subsidiary would fail to meet the preceding requirements as an Unrestricted Subsidiary, it shall thereafter cease to be an Unrestricted Subsidiary for purposes of this Indenture and any Indebtedness of such Subsidiary shall be deemed to be incurred by a Restricted Subsidiary of the Partnership as of such date and, if such Indebtedness is not permitted to be incurred as of such date under Section 4.09 hereof, the Partnership shall be in default of such covenant.

“ Voting Stock ” of any Person as of any date means the Equity Interests of such Person pursuant to which the holders thereof have the general voting power under ordinary circumstances to elect at least a majority of the board of directors, managers, general partners or trustees of such Person (regardless of whether, at the time, Equity Interests of any other class or classes shall have, or might have, voting power by reason of the occurrence of any contingency) or, with respect to a partnership (whether general or limited), any general partner interest in such partnership.

“ Weighted Average Life to Maturity ” means, when applied to any Indebtedness at any date, the number of years obtained by dividing: (1) the sum of the products obtained by multiplying (a) the amount of each then remaining installment, sinking fund, serial maturity or other required payments of principal, including payment at final maturity, in respect thereof, by (b) the number of years (calculated to the nearest one-twelfth) that will elapse between such date and the making of such payment; by (2) the then outstanding principal amount of such Indebtedness.

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Section 1.02.                  Other Definitions.

Section 1.03.                  Incorporation by Reference of Trust Indenture Act.

Whenever this Indenture refers to a provision of the TIA, the provision is incorporated by reference in and made a part of this Indenture.

The following TIA terms used in this Indenture have the following meanings:

“indenture securities” means the Notes and the Guarantees;

“indenture security holder” means a Holder of a Note;

“indenture to be qualified” means this Indenture;

“indenture trustee” or “institutional trustee” means the Trustee;

“obligor” on the Notes means the Partnership, MarkWest Finance or any Subsidiary Guarantor and any successor obligor upon the Notes.

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All other terms used in this Indenture that are defined by the TIA, defined by TIA reference to another statute or defined by SEC rule under the TIA have the meanings so assigned to them.

Section 1.04.                  Rules of Construction.

Unless the context otherwise requires:

(1)           a term has the meaning assigned to it;

(2)           an accounting term not otherwise defined has the meaning assigned to it in accordance with GAAP;

(3)           “or” is not exclusive;

(4)           words in the singular include the plural, and in the plural include the singular;

(5)           provisions apply to successive events and transactions; and

(6)           references to sections of or rules under the Securities Act or the Exchange Act shall be deemed to include substitute, replacement of successor sections or rules adopted by the SEC from time to time.

ARTICLE 2
THE NOTES

Section 2.01.                  Form and Dating.

The Notes and the Trustee’s certificate of authentication shall be substantially in the form of Exhibit A hereto.  The notation on each Note relating to the Guarantees shall be substantially in the form set forth on Exhibit D, which is a part of this Indenture.  The Notes may have notations, legends or endorsements required by law, stock exchange rule or usage.  Each Note shall be dated the date of its authentication.  The Notes shall be in minimum denominations of $2,000 or integral multiples of $1,000 in excess thereof.

The terms and provisions contained in the Notes (including the Guarantees) shall constitute, and are hereby expressly made, a part of this Indenture and the Partnership, MarkWest Finance, the Subsidiary Guarantors, and the Trustee, by their execution and delivery of this Indenture, expressly agree to such terms and provisions and to be bound thereby.  However, to the extent permitted by law, if any provision of any Note conflicts with the express provisions of this Indenture, the provisions of this Indenture shall govern and be controlling.

Notes issued in global form shall be substantially in the form of Exhibit A attached hereto (including the Global Note Legend and the “Schedule of Exchanges in the Global Note” attached thereto).  Notes issued in definitive form shall be substantially in the form of Exhibit A attached hereto (but without the Global Note Legend, the phrase identified in footnote 3 thereto and without the “Schedule of Exchanges of Interests in the Global Note” attached thereto).  Each

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Global Note shall represent such of the outstanding Notes as shall be specified therein and each shall provide that it shall represent the aggregate principal amount of outstanding Notes from time to time endorsed thereon and that the aggregate principal amount of outstanding Notes represented thereby may from time to time be reduced or increased, as appropriate, to reflect exchanges and redemptions.  Any endorsement of a Global Note to reflect the amount of any increase or decrease in the aggregate principal amount of outstanding Notes represented thereby shall be made by the Trustee or the Note Custodian, at the direction of the Trustee, in accordance with instructions given by the Holder thereof as required by Section 2.06 hereof.

Section 2.02.                  Execution and Authentication.

One Officer of the Partnership and one Officer of MarkWest Finance shall sign the Notes for the Partnership and MarkWest Finance, respectively, by manual or facsimile signature.

If an Officer whose signature is on a Note no longer holds that office at the time a Note is authenticated, the Note shall nevertheless be valid.

A Note shall not be valid until authenticated by the manual signature of the Trustee.  The signature shall be conclusive evidence that the Note has been authenticated under this Indenture.

The Trustee shall, upon a written order of the Partnership and MarkWest Finance signed by one Officer of the Partnership and one Officer of MarkWest Finance, authenticate (i) $400,000,000 aggregate principal amount of Notes, with the Guarantees endorsed thereon, for original issue on the Issue Date and (ii) from time to time thereafter any amount of additional Notes specified by the Issuers, in each case, upon a written order of the Partnership and MarkWest Finance signed by one Officer of the Partnership and one Officer of MarkWest Finance.  Such order shall specify (a) the amount of the Notes of each series to be authenticated and the date of original issue thereof, and (b) whether the Notes are Series A Notes or Exchange Notes.  The aggregate principal amount of Notes of either series outstanding at any time may not exceed the aggregate principal amount of Notes of such series authorized for issuance by the Issuers pursuant to one or more written orders of the Issuers, except as provided in Section 2.07 hereof.  Subject to the foregoing, the aggregate principal amount of Notes of either series that may be issued under this Indenture shall not be limited.

The Series A Notes issued on the Issue Date and any additional Series A Notes subsequently issued, together with the Exchange Notes issued in exchange therefor, shall be treated as a single class for all purposes under this Indenture, including, without limitation, waivers, amendments, redemptions and offers to purchase.

The Trustee may appoint an authenticating agent acceptable to the Issuers to authenticate Notes.  An authenticating agent may authenticate Notes whenever the Trustee may do so.  Each reference in this Indenture to authentication by the Trustee includes authentication by such agent.  An authenticating agent has the same rights as an Agent to deal with Holders or an Affiliate of either of the Issuers.

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Section 2.03.                  Registrar and Paying Agent.

The Partnership, MarkWest Finance and the Subsidiary Guarantors shall maintain in the continental United States an office or agency where Notes may be presented for registration of transfer or for exchange (“Registrar”) and an office or agency where Notes may be presented for payment (“Paying Agent”).  The Registrar shall keep a register of the Notes and of their transfer and exchange.  The Issuers may appoint one or more co-registrars and one or more additional paying agents.  The term “Registrar” includes any co-registrar and the term “Paying Agent” includes any additional paying agent.  The Issuers may change any Paying Agent or Registrar without notice to any Holder.  The Issuers shall notify the Trustee in writing of the name and address of any Agent not a party to this Indenture.  If the Issuers fail to appoint or maintain another entity as Registrar or Paying Agent, the Trustee shall act as such.  The Partnership, MarkWest Finance or any of their Subsidiaries may act as Paying Agent or Registrar.

The Issuers initially appoint The Depository Trust Company (“DTC”) to act as Depositary with respect to the Global Notes.

The Issuers initially appoint the Trustee to act as the Registrar and Paying Agent and to act as Note Custodian with respect to the Global Notes at the Corporate Trust Office of the Trustee.

Section 2.04.                  Paying Agent to Hold Money in Trust.

The Issuers shall require each Paying Agent other than the Trustee to agree in writing that the Paying Agent will hold in trust for the benefit of Holders or the Trustee all money held by the Paying Agent for the payment of principal, premium, if any, or interest or Additional Interest, if any, on the Notes, and will notify the Trustee of any default by the Partnership, MarkWest Finance or the Subsidiary Guarantors in making any such payment.  While any such default continues, the Trustee may require a Paying Agent to pay all money held by it to the Trustee.  The Issuers at any time may require a Paying Agent to pay all money held by it to the Trustee.  Upon payment over to the Trustee, the Paying Agent (if other than an Issuer or a Subsidiary Guarantor) shall have no further liability for the money.  If an Issuer or a Subsidiary Guarantor acts as Paying Agent, it shall segregate and hold in a separate trust fund for the benefit of the Holders all money held by it as Paying Agent.  Upon any bankruptcy or reorganization proceedings relating to the Partnership or MarkWest Finance, the Trustee shall serve as Paying Agent for the Notes.

Section 2.05.                  Holder Lists.

The Trustee shall preserve in as current a form as is reasonably practicable the most recent list available to it of the names and addresses of all Holders and shall otherwise comply with TIA Section 312(a).  If the Trustee is not the Registrar, the Issuers shall furnish to the Trustee at least seven Business Days before each Interest Payment Date and at such other times as the Trustee may request in writing, a list in such form and as of such date as the Trustee may reasonably require of the names and addresses of the Holders of Notes and the Issuers shall otherwise comply with TIA Section 312(a).

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Section 2.06.                  Transfer and Exchange.

(a)                                 Transfer and Exchange of Global Notes.  A Global Note may not be transferred as a whole except by the Depositary to a nominee of the Depositary, by a nominee of the Depositary to the Depositary or to another nominee of the Depositary, or by the Depositary or any such nominee to a successor Depositary or a nominee of such successor Depositary.  All Global Notes may be exchanged by the Issuers for Certificated Notes if (i) the Issuers deliver to the Trustee notice from the Depositary that it is unwilling or unable to continue to act as Depositary or that it is no longer a clearing agency registered under the Exchange Act and, in either case, a successor Depositary is not appointed by the Issuers within 90 days after the date of such notice from the Depositary, or (ii) if an Event of Default occurs and is continuing and the Depositary notifies the Trustee of its decision to exchange the Global Notes for Certificated Notes.  Whenever a Global Note is exchanged as a whole for one or more Certificated Notes, it shall be surrendered by the Holder thereof to the Trustee for cancellation.  Whenever a Global Note is exchanged in part for one or more Certificated Notes, it shall be surrendered by the Holder thereof to the Trustee and the Trustee shall make the appropriate notations to the Schedule of Exchanges of Interests in the Global Notes attached thereto pursuant to Section 2.01 hereof.  All Certificated Notes issued in exchange for a Global Note or any portion thereof shall be registered in such names, and delivered, as the Depositary shall instruct the Trustee.  Global Notes also may be exchanged or replaced, in whole or in part, as provided in Sections 2.07 and 2.10 hereof.  Every Note authenticated and delivered in exchange for, or in lieu of, a Global Note or any portion thereof, pursuant to Section 2.07 or 2.10 hereof, shall be authenticated and delivered in the form of, and shall be, a Global Note.  A Global Note may not be exchanged for another Note other than as provided in this Section 2.06(a); however, beneficial interests in a Global Note may be transferred and exchanged as provided in Section 2.06(b) or (f) hereof.

(b)                                Transfer and Exchange of Beneficial Interests in the Global Notes.  The transfer and exchange of beneficial interests in the Global Notes shall be effected through the Depositary, in accordance with the provisions of this Indenture and the Applicable Procedures.  Beneficial interests in the Restricted Global Notes shall be subject to restrictions on transfer comparable to those set forth herein to the extent required by the Securities Act.  Transfers of beneficial interests in the Global Notes also shall require compliance with either subparagraph (i) or (ii) below, as applicable, as well as one or more of the other following subparagraphs as applicable:

(i)            Transfer of Beneficial Interests in the Same Global Note.  Beneficial interests in any Restricted Global Note may be transferred to Persons who take delivery thereof in the form of a beneficial interest in the same Restricted Global Note in accordance with the transfer restrictions set forth in the Private Placement Legend; provided, however, that prior to the expiration of the Distribution Compliance Period transfers of beneficial interests in the Regulation S Global Note may not be made to a U.S. Person or for the account or benefit of a U.S. Person (other than an Initial Purchaser).  Beneficial interests in any Unrestricted Global Note may be transferred only to Persons who take delivery thereof in the form of a beneficial interest in an Unrestricted Global Note.  No written orders or instructions shall be required to be delivered to the Registrar to effect the transfers described in this Section 2.06(b)(i).

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(ii)                                 All Other Transfers and Exchanges of Beneficial Interests in Global Notes.  In connection with all transfers and exchanges of beneficial interests (other than a transfer of a beneficial interest in a Global Note to a Person who takes delivery thereof in the form of a beneficial interest in the same Global Note), the transferor of such beneficial interest must deliver to the Registrar (A) a written order from a Participant or an Indirect Participant given to the Depositary in accordance with the Applicable Procedures directing the Depositary to credit or cause to be credited a beneficial interest in another Global Note in an amount equal to the beneficial interest to be transferred or exchanged and (B) instructions given in accordance with the Applicable Procedures containing information regarding the Participant account to be credited with such increase.  Upon an Exchange Offer by the Issuers in accordance with Section 2.06(f) hereof, the requirements of this Section 2.06(b)(ii) shall be deemed to have been satisfied upon receipt by the Registrar of the instructions contained in the Letters of Transmittal delivered by the holders of such beneficial interests in the Restricted Global Notes.  Upon satisfaction of all of the requirements for transfer or exchange of beneficial interests in Global Notes contained in this Indenture, the Notes and otherwise applicable under the Securities Act, the Trustee shall adjust the principal amount of the relevant Global Note(s) pursuant to Section 2.06(h) hereof.

(iii)                              Transfer of Beneficial Interests to Another Restricted Global Note.  A beneficial interest in any Restricted Global Note may be transferred to a Person who takes delivery thereof in the form of a beneficial interest in another Restricted Global Note if the transfer complies with the requirements of clause (ii) above and the Registrar receives the following:

(A)           if the transferee will take delivery in the form of a beneficial interest in the 144A Global Note, then the transferor must deliver a certificate in the form of Exhibit B hereto, including the certifications in item (1) thereof;

(B)            if the transferee will take delivery in the form of a beneficial interest in the Regulation S Global Note, then the transferor must deliver a certificate in the form of Exhibit B hereto, including the certifications in item (2) thereof; and

(C)            if the transferee will take delivery in the form of a beneficial interest in the IAI Global Note, then the transferor must deliver (x) a certificate in the form of Exhibit B hereto, including the certifications and certificates and Opinion of Counsel required by item (3)(c) thereof, if applicable.

(iv)                              Transfer and Exchange of Beneficial Interests in a Restricted Global Note for Beneficial Interests in the Unrestricted Global Note.  A beneficial interest in any Restricted Global Note may be exchanged by any holder thereof for a beneficial interest in an Unrestricted Global Note or transferred to a Person who takes delivery thereof in the form of a beneficial interest in an Unrestricted Global Note if the exchange or transfer complies with the requirements of clause (ii) above and:

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(A)                              such exchange or transfer is effected pursuant to an Exchange Offer in accordance with the applicable Registration Rights Agreement and the holder of the beneficial interest to be transferred, in the case of an exchange, or the transferee, in the case of a transfer, is not (i) a broker-dealer, (ii) a Person participating in the distribution of the Exchange Notes or (iii) a Person who is an affiliate (as defined in Rule 144) of the Partnership;

(B)                                any such transfer is effected pursuant to a Shelf Registration Statement in accordance with the applicable Registration Rights Agreement;

(C)                                any such transfer is effected by a Participating Broker-Dealer pursuant to an Exchange Offer Registration Statement in accordance with the applicable Registration Rights Agreement; or

(D)                               the Registrar receives the following:

(i)              if the holder of such beneficial interest in a Restricted Global Note proposes to exchange such beneficial interest for a beneficial interest in an Unrestricted Global Note, a certificate from such holder in the form of Exhibit C hereto, including the certifications in item (1)(a) thereof;

(ii)             if the holder of such beneficial interest in a Restricted Global Note proposes to transfer such beneficial interest to a Person who shall take delivery thereof in the form of a beneficial interest in an Unrestricted Global Note, a certificate from such holder in the form of Exhibit B hereto, including the certifications in item (4) thereof; and

(iii)            in each such case set forth in this subparagraph (D), an opinion of counsel in form reasonably acceptable to the Issuers to the effect that such exchange or transfer is in compliance with the Securities Act, that the restrictions on transfer contained herein and in the Private Placement Legend are not required in order to maintain compliance with the Securities Act and such beneficial interest is being exchanged or transferred in compliance with any applicable blue sky securities laws of any state of the United States.

If any such transfer is effected pursuant to subparagraph (B) or (D) above at a time when an Unrestricted Global Note has not yet been issued, the Issuers shall issue and, upon receipt of an authentication order in accordance with Section 2.02 hereof, the Trustee shall authenticate one or more Unrestricted Global Notes (accompanied by a notation of the Guarantees duly endorsed by the Subsidiary Guarantors) in an aggregate principal amount equal to the principal amount of beneficial interests transferred pursuant to subparagraph (B) or (D) above.

Beneficial interests in an Unrestricted Global Note cannot be exchanged for, or transferred to Persons who take delivery thereof in the form of, a beneficial interest in a Restricted Global Note.

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(c)                                  Transfer or Exchange of Beneficial Interests for Certificated Notes.  A beneficial interest in a Global Note cannot be exchanged for, or transferred to Persons who take delivery thereof in the form of, a Certificated Note, except in the circumstances specified in Section 2.06(a).

(d)                                 Transfer and Exchange of Certificated Notes for Beneficial Interests.  Certificated Notes cannot be exchanged for, or transferred to Persons who take delivery thereof in the form of, a beneficial interest in a Global Note.

(e)                                  Transfer and Exchange of Certificated Notes for Certificated Notes.  Upon request by a Holder of Certificated Notes and such Holder’s compliance with the provisions of this Section 2.06(e), the Registrar shall register the transfer or exchange of Certificated Notes.  Prior to such registration of transfer or exchange, the requesting Holder shall present or surrender to the Registrar the Certificated Notes duly endorsed or accompanied by a written instruction of transfer in form satisfactory to the Registrar duly executed by such Holder or by his attorney, duly authorized in writing.  In addition, the requesting Holder shall provide any additional certifications, documents and information, as applicable, pursuant to the provisions of this Section 2.06(e).

(i)              Restricted Certificated Notes may be transferred to and registered in the name of Persons who take delivery thereof if the Registrar receives the following:

(A)           if the transfer will be made pursuant to Rule 144A under the Securities Act, then the transferor must deliver a certificate in the form of Exhibit B hereto, including the certifications in item (1) thereof;

(B)            if the transfer will be made pursuant to Rule 903 or Rule 904, then the transferor must deliver a certificate in the form of Exhibit B hereto, including the certifications in item (2) thereof; and

(C)            if the transfer will be made pursuant to any other exemption from the registration requirements of the Securities Act, then the transferor must deliver a certificate in the form of Exhibit B hereto, including the certifications, certificates and Opinion of Counsel required by item (3) thereof, if applicable.

(ii)           Any Restricted Certificated Note may be exchanged by the Holder thereof for an Unrestricted Certificated Note or transferred to a Person or Persons who take delivery thereof in the form of an Unrestricted Certificated Note if:

(A)           such exchange or transfer is effected pursuant to an Exchange Offer in accordance with the applicable Registration Rights Agreement and the Holder, in the case of an exchange, or the transferee, in the case of a transfer, is not (i) a broker-dealer, (ii) a Person participating in the distribution of the Exchange Notes or (iii) a Person who is an affiliate (as defined in Rule 144) of the Partnership;

(B)            any such transfer is effected pursuant to a Shelf Registration Statement in accordance with the applicable Registration Rights Agreement;

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(C)            any such transfer is effected by a Participating Broker-Dealer pursuant to an Exchange Offer Registration Statement in accordance with the applicable Registration Rights Agreement; or

(D)           the Registrar receives the following:

(i)            if the Holder of such Restricted Certificated Notes proposes to exchange such Notes for an Unrestricted Certificated Note, a certificate from such Holder in the form of Exhibit C hereto, including the certifications in item (1)(b) thereof;

(ii)           if the Holder of such Restricted Certificated Notes proposes to transfer such Notes to a Person who shall take delivery thereof in the form of an Unrestricted Certificated Note, a certificate from such Holder in the form of Exhibit B hereto, including the certifications in item (4) thereof; and

(iii)          in each such case set forth in this subparagraph (D), an opinion of counsel in form reasonably acceptable to the Issuers to the effect that such exchange or transfer is in compliance with the Securities Act, that the restrictions on transfer contained herein and in the Private Placement Legend are not required in order to maintain compliance with the Securities Act, and such Restricted Certificated Note is being exchanged or transferred in compliance with any applicable blue sky securities laws of any state of the United States.

(iii)          A Holder of Unrestricted Certificated Notes may transfer such Notes to a Person who takes delivery thereof in the form of an Unrestricted Certificated Note.  Upon receipt of a request for such a transfer, the Registrar shall register the Unrestricted Certificated Notes pursuant to the instructions from the Holder thereof.  Unrestricted Certificated Notes cannot be exchanged for or transferred to Persons who take delivery thereof in the form of a Restricted Certificated Note.

(f)            Exchange Offer.  Upon the occurrence of an Exchange Offer in accordance with a Registration Rights Agreement, the Issuers shall issue and, upon receipt of an authentication order in accordance with Section 2.02, the Trustee shall authenticate (i) one or more Unrestricted Global Notes (accompanied by a notation of the Guarantees duly endorsed by the Subsidiary Guarantors) in an aggregate principal amount equal to the principal amount of the beneficial interests in the Restricted Global Notes tendered for acceptance by Persons that are not (x) broker-dealers (excluding broker-dealers that acquired such beneficial interests in Restricted Global Notes as a result of market-making activities or other trading activities (other than such beneficial interests in Restricted Global Notes acquired directly from the Issuers or any of their affiliates (as defined in Rule 144) thereof)), (y) Persons participating in the distribution of the Exchange Notes or (z) Persons who are affiliates of the Partnership and accepted for exchange in the Exchange Offer and (ii) Unrestricted Certificated Notes (accompanied by a notation of the Guarantees duly endorsed by the Subsidiary Guarantors) in an aggregate principal amount equal to the principal amount of the Restricted Certificated Notes accepted for exchange in the

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Exchange Offer.  Concurrently with the issuance of such Notes, the Trustee shall cause the aggregate principal amount of the applicable Restricted Global Notes to be reduced accordingly, and the Issuers shall execute and the Trustee shall authenticate and deliver to the Persons designated by the Holders of Restricted Certificated Notes so accepted Unrestricted Certificated Notes in the appropriate principal amount.

(g)            Legends.  The following legends shall appear on the face of all Global Notes and Certificated Notes issued under this Indenture unless specifically stated otherwise in the applicable provisions of this Indenture.

(i)             Private Placement Legend.

(A)          Except as permitted by subparagraph (B) below, each Global Note and each Certificated Note (and all Notes issued in exchange therefor or substitution thereof) shall bear the legend in substantially the following form:

“THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), OR THE SECURITIES LAWS OF ANY STATE OR OTHER JURISDICTION.  NEITHER THIS SECURITY NOR ANY INTEREST OR PARTICIPATION HEREIN MAY BE REOFFERED, SOLD, ASSIGNED, TRANSFERRED, PLEDGED, ENCUMBERED OR OTHERWISE DISPOSED OF IN THE ABSENCE OF SUCH REGISTRATION OR UNLESS SUCH TRANSACTION IS EXEMPT FROM, OR NOT SUBJECT TO, SUCH REGISTRATION.  THE HOLDER OF THIS SECURITY, BY ITS ACCEPTANCE HEREOF, AGREES ON ITS OWN BEHALF AND ON BEHALF OF ANY INVESTOR ACCOUNT FOR WHICH IT HAS PURCHASED SECURITIES, TO OFFER, SELL OR OTHERWISE TRANSFER SUCH SECURITY, PRIOR TO THE DATE (THE “RESALE RESTRICTION TERMINATION DATE”) THAT IS [ IN THE CASE OF NOTES SOLD IN RELIANCE ON RULE 144A UNDER THE SECURITIES ACT :  ONE YEAR ] [ IN THE CASE OF NOTES SOLD IN RELIANCE ON REGULATION S UNDER THE SECURITIES ACT: 40 DAYS ] AFTER THE LATER OF THE ORIGINAL ISSUE DATE HEREOF AND THE LAST DATE ON WHICH EITHER ISSUER OR ANY AFFILIATE OF EITHER ISSUER WAS THE OWNER OF THIS SECURITY (OR ANY PREDECESSOR OF SUCH SECURITY), ONLY (A) TO AN ISSUER OR ITS SUBSIDIARY, (B) PURSUANT TO A REGISTRATION STATEMENT THAT HAS BEEN DECLARED EFFECTIVE UNDER THE SECURITIES ACT, (C) FOR SO LONG AS THE SECURITIES ARE ELIGIBLE FOR RESALE PURSUANT TO RULE 144A UNDER THE SECURITIES ACT, TO A PERSON IT REASONABLY BELIEVES IS A “QUALIFIED INSTITUTIONAL BUYER” AS DEFINED IN RULE 144A UNDER THE SECURITIES ACT THAT PURCHASES FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF A QUALIFIED INSTITUTIONAL BUYER TO WHOM NOTICE IS GIVEN THAT THE TRANSFER IS BEING MADE IN RELIANCE ON RULE 144A, (D) PURSUANT TO OFFERS AND SALES THAT OCCUR OUTSIDE THE UNITED STATES WITHIN THE MEANING OF REGULATION S UNDER

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THE SECURITIES ACT, (E) TO AN INSTITUTIONAL “ACCREDITED INVESTOR” WITHIN THE MEANING OF RULE 501(a)(1), (2), (3) OR (7) UNDER THE SECURITIES ACT THAT IS AN INSTITUTIONAL ACCREDITED INVESTOR ACQUIRING THE SECURITY FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF SUCH AN INSTITUTIONAL ACCREDITED INVESTOR, IN EACH CASE IN A MINIMUM PRINCIPAL AMOUNT OF THE SECURITIES OF $250,000, FOR INVESTMENT PURPOSES AND NOT WITH A VIEW TO OR FOR OFFER OR SALE IN CONNECTION WITH ANY DISTRIBUTION IN VIOLATION OF THE SECURITIES ACT, OR (F) PURSUANT TO ANOTHER AVAILABLE EXEMPTION FROM THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT, SUBJECT TO THE ISSUERS’ AND THE TRUSTEE’S RIGHT PRIOR TO ANY SUCH OFFER, SALE OR TRANSFER PURSUANT TO CLAUSES (C), (D), (E) OR (F) TO REQUIRE THE DELIVERY OF AN OPINION OF COUNSEL, CERTIFICATION AND/OR OTHER INFORMATION SATISFACTORY TO EACH OF THEM.  THIS LEGEND WILL BE REMOVED UPON THE REQUEST OF THE HOLDER AFTER THE RESALE RESTRICTION TERMINATION DATE.”

(B)           Notwithstanding the foregoing, any Global Note or Certificated Note issued pursuant to subparagraphs (b)(iv), (e)(ii), (e)(iii) or (f) of this Section 2.06 (and all Notes issued in exchange therefor or substitution thereof) shall not bear the Private Placement Legend.

(ii)            Global Note Legend.  Each Global Note shall bear a legend in substantially the following form:

“THIS GLOBAL NOTE IS HELD BY THE DEPOSITARY (AS DEFINED IN THE INDENTURE GOVERNING THIS NOTE) OR ITS NOMINEE IN CUSTODY FOR THE BENEFIT OF THE BENEFICIAL OWNERS HEREOF, AND IS NOT TRANSFERABLE TO ANY PERSON UNDER ANY CIRCUMSTANCES EXCEPT THAT (I) THE TRUSTEE MAY MAKE SUCH NOTATIONS HEREON AS MAY BE REQUIRED PURSUANT TO SECTION 2.06 OF THE INDENTURE, (II) THIS GLOBAL NOTE MAY BE EXCHANGED PURSUANT TO SECTION 2.06(a) OF THE INDENTURE, (III) THIS GLOBAL NOTE MAY BE DELIVERED TO THE TRUSTEE FOR CANCELLATION PURSUANT TO SECTION 2.11 OF THE INDENTURE AND (IV) THIS GLOBAL NOTE MAY BE TRANSFERRED TO A SUCCESSOR DEPOSITARY WITH THE PRIOR WRITTEN CONSENT OF THE ISSUERS.”

“UNLESS AND UNTIL IT IS EXCHANGED IN WHOLE OR IN PART FOR NOTES IN DEFINITIVE FORM, THIS NOTE MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE BY THE DEPOSITARY TO A NOMINEE OF THE DEPOSITARY OR BY A NOMINEE OF THE DEPOSITARY TO THE DEPOSITARY OR ANOTHER NOMINEE OF THE DEPOSITARY OR BY THE DEPOSITARY OR ANY SUCH NOMINEE TO A SUCCESSOR

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DEPOSITARY OR A NOMINEE OF SUCH SUCCESSOR DEPOSITARY.  UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY (55 WATER STREET, NEW YORK, NEW YORK) (“DTC”), TO THE ISSUERS OR THEIR AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR SUCH OTHER NAME AS MAY BE REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT IS MADE TO CEDE & CO. OR SUCH OTHER ENTITY AS MAY BE REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.”

(h)            Cancellation and/or Adjustment of Global Notes.  At such time as all beneficial interests in a particular Global Note have been exchanged for Certificated Notes or a particular Global Note has been redeemed, repurchased or canceled in whole and not in part, each such Global Note shall be returned to or retained and canceled by the Trustee in accordance with Section 2.11 hereof.  At any time prior to such cancellation, if any beneficial interest in a Global Note is exchanged for or transferred to a Person who will take delivery thereof in the form of a beneficial interest in another Global Note or for Certificated Notes, the principal amount of Notes represented by such Global Note shall be reduced accordingly and an endorsement shall be made on such Global Note, by the Trustee or by the Depositary at the direction of the Trustee, to reflect such reduction; and if the beneficial interest is being exchanged for or transferred to a Person who will take delivery thereof in the form of a beneficial interest in another Global Note, such other Global Note shall be increased accordingly and an endorsement shall be made on such Global Note, by the Trustee or by the Depositary at the direction of the Trustee, to reflect such increase.

(i)             General Provisions Relating to Transfers and Exchanges.

(i)            To permit registrations of transfers and exchanges, the Issuers shall execute and the Trustee shall authenticate Global Notes and Certificated Notes (in each case, accompanied by a notation of the Guarantees duly endorsed by the Subsidiary Guarantors) upon the Issuers’ order or at the Registrar’s request.

(ii)           No service charge shall be made to a holder of a beneficial interest in a Global Note or to a Holder of a Certificated Note for any registration of transfer or exchange, but the Issuers may require payment of a sum sufficient to cover any transfer tax or similar governmental charge payable in connection therewith (other than any such transfer taxes or similar governmental charge payable upon exchange or transfer pursuant to Sections 2.10, 3.06, 3.09, 4.06 and 9.05 hereof).

(iii)          The Registrar shall not be required to register the transfer of or exchange any Note selected for redemption in whole or in part, except the unredeemed portion of any Note being redeemed in part.

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(iv)          All Global Notes and Certificated Notes (in each case, accompanied by a notation of the Guarantees duly endorsed by the Subsidiary Guarantors) issued upon any registration of transfer or exchange of Global Notes or Certificated Notes shall be the valid obligations of the Issuers and the Subsidiary Guarantors, evidencing the same debt, and entitled to the same benefits under this Indenture, as the Global Notes or Certificated Notes surrendered upon such registration of transfer or exchange.

(v)           The Issuers shall not be required (A) to issue, to register the transfer of or to exchange Notes during a period of 15 days before a selection of Notes for redemption, (B) to register the transfer of or to exchange any Note so selected for redemption in whole or in part, except the unredeemed portion of any Note being redeemed in part or (C) to register the transfer of or to exchange a Note between a record date and the next succeeding Interest Payment Date.

(vi)          Prior to due presentment for the registration of a transfer of any Note, the Trustee, any Agent, the Issuers and the Subsidiary Guarantors may deem and treat the Person in whose name any Note is registered as the absolute owner of such Note for the purpose of receiving payment of principal of and interest on such Notes and for all other purposes, and none of the Trustee, any Agent, the Issuers or any Subsidiary Guarantor shall be affected by notice to the contrary.

(vii)         The Trustee shall authenticate Global Notes and Certificated Notes (in each case, accompanied by a notation of the Guarantees duly endorsed by the Subsidiary Guarantors) in accordance with the provisions of Section 2.02 hereof.

(viii)        All certifications, certificates and opinions of counsel required to be submitted to the Registrar pursuant to this Section 2.06 to effect a transfer or exchange may be submitted by facsimile.

(ix)           Each Holder of a Note agrees to indemnify the Issuers and the Trustee against any liability that may result from the transfer, exchange or assignment of such Holder’s Note in violation of any provision of this Indenture and/or applicable United States federal or state securities law.

(j)             Each beneficial owner of an interest in a Note agrees to indemnify the Issuers and the Trustee against any liability that may result from the transfer, exchange or assignment by such beneficial owner of such interest in violation of any provision of this Indenture and/or applicable United States federal or state securities law.

(k)            The Trustee shall have no obligation or duty to monitor, determine or inquire as to compliance with any restrictions on transfer imposed under this Indenture or under applicable law with respect to any transfer of any interest in any Note (including any transfers between or among beneficial owners of interest in any Global Note) other than to require delivery of such certificate and other documentation or evidence as are expressly required by, and to do so if and when expressly required by the terms of, this Indenture, and to examine the same to determine substantial compliance as to form with the express requirements hereof.

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Section 2.07.                  Replacement Notes.

If any mutilated Note is surrendered to the Trustee or either of the Issuers and the Trustee receives evidence to its satisfaction of the destruction, loss or theft of any Note, the Issuers shall issue and the Trustee, upon the written order of the Issuers signed by one Officer of the Partnership and one Officer of MarkWest Finance, shall authenticate a replacement Note (accompanied by a notation of the Guarantees duly endorsed by the Subsidiary Guarantors) if the Trustee’s requirements are met.  An indemnity bond must be supplied by the Holder that is sufficient in the judgment of the Trustee and the Issuers to protect the Issuers, the Subsidiary Guarantors, the Trustee, any Agent and any authenticating agent from any loss that any of them may suffer if a Note is replaced.  The Issuers may charge for their expenses in replacing a Note.

Every replacement Note is an additional obligation of the Issuers and the Subsidiary Guarantors and shall be entitled to all of the benefits of this Indenture equally and proportionately with all other Notes duly issued hereunder.  The provisions of this Section 2.07 are exclusive and shall preclude (to the extent lawful) all other rights and remedies with respect to the replacement of mutilated, destroyed, lost or stolen Notes.

Section 2.08.                  Outstanding Notes.

The Notes outstanding at any time are all the Notes authenticated by the Trustee except for those canceled by it, those delivered to it for cancellation, those reductions in the interests in a Global Note effected by the Trustee in accordance with the provisions hereof, and those described in this Section as not outstanding.  Except as set forth in Section 2.09 hereof, a Note does not cease to be outstanding because an Issuer or an Affiliate of an Issuer holds the Note.

If a Note is replaced pursuant to Section 2.07 hereof, it ceases to be outstanding unless the Trustee receives proof satisfactory to it that the replaced Note is held by a bona fide purchaser.

If the principal amount of any Note is considered paid under Section 4.01 hereof, it ceases to be outstanding and interest (including Additional Interest, if applicable) on it ceases to accrue.

If the Paying Agent (other than an Issuer or a Subsidiary or an Affiliate of an Issuer) holds, on a redemption date or other maturity date, money sufficient to pay Notes payable on that date, then on and after that date such Notes shall be deemed to be no longer outstanding and shall cease to accrue interest (including Additional Interest, if any).

Section 2.09.                  Treasury Notes.

In determining whether the Holders of the required principal amount of Notes have concurred in any direction, waiver or consent, Notes owned by an Issuer, by any Subsidiary Guarantor or by any Person directly or indirectly controlling or controlled by or under direct or indirect common control with the Partnership or any Subsidiary Guarantor, shall be considered as though not outstanding, except that for the purposes of determining whether the Trustee shall be protected in relying on any such direction, waiver or consent, only Notes that a Responsible Officer of the Trustee actually knows are so owned shall be so disregarded.

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Section 2.10.                  Temporary Notes.

Until definitive Notes are ready for delivery, the Issuers may prepare and the Trustee shall authenticate temporary Notes (accompanied by a notation of the Guarantees duly endorsed by the Subsidiary Guarantors) upon a written order of the Issuers signed by one Officer of the Partnership and one Officer of MarkWest Finance.  Temporary Notes shall be substantially in the form of definitive Notes but may have variations that the Issuers consider appropriate for temporary Notes and as shall be reasonably acceptable to the Trustee.  Without unreasonable delay, the Issuers shall prepare and the Trustee shall authenticate definitive Notes (accompanied by a notation of the Guarantees duly endorsed by the Subsidiary Guarantors) in exchange for temporary Notes.

Holders of temporary Notes shall be entitled to all of the benefits of this Indenture.

Section 2.11.                  Cancellation.