MASTER LEASE AGREEMENT

Exhibit 10.21

MASTER LEASE AGREEMENT

This MASTER LEASE AGREEMENT (this “ Master Lease ”), dated as of February 26, 2009, is between Caterpillar Financial Services Corporation (“ Lessor ”), a Delaware corporation whose address is 2120 West End Avenue, Nashville, Tennessee 37203, and CDM Resource Management LLC (“ Lessee ”), a Texas limited liability company with a principal address of 20405 Tomball Pkwy, Suite 310, Houston, TX, 77070.

In consideration of the mutual covenants and agreements hereinafter set forth, the parties hereto agree as follows:

Section 1 . Definitions . The capitalized terms used in this Master Lease and not otherwise defined herein shall have the respective meanings specified in Appendix A hereto, unless the context hereof shall otherwise require.

Section 2 . Master Lease . Lessor hereby leases to Lessee and Lessee hereby leases from Lessor the Equipment and other property described on each Lease Schedule executed from time to time by Lessor and Lessee in a form acceptable to Lessor (each a “ Schedule ”). Each Schedule shall expressly incorporate the terms of this Master Lease and shall constitute a separate lease along with any other writing expressly incorporated into the Master Lease or the Schedule. The terms “ Lease ” or “ this Lease ” as used herein shall refer to each and every Schedule that incorporates this Master Lease and any other writing expressly incorporated into the Master Lease or such Schedule. In the event of any conflict between the Master Lease and any Schedule, the terms of the Schedule shall control. Upon Lessee’s satisfaction of all conditions precedent to effectiveness of this Master Lease, including those set forth in Section 9 with respect to the execution of Schedules: (a) this Master Lease shall constitute a legal commitment by Lessor to lease equipment in accordance with the terms herein and in each such Schedule and (b) Lessor shall be obligated to enter into Schedules and purchase and lease the equipment or other property pursuant thereto. After executing a Schedule, Lessor shall have no obligation to purchase or finance any Equipment until the satisfaction of all conditions precedent to Lessor’s purchase of Equipment pursuant to the terms of the Master Lease and said Schedule.

Section 3 . Title; UCC 2A Finance Lease; Waivers .

(a) Lessee and Lessor intend that: (i) each Lease constitutes a true “lease” that is a “finance lease” as such terms are defined in Article 2A of the UCC and does not create a “security interest” as defined in the UCC; (ii) Lessor is and shall remain the owner of the Equipment (unless sold by Lessor pursuant to any Lease Document); (iii) Lessee shall not acquire any right, title, equity or interest in or to such Equipment other than the right to possess and use the Equipment in accordance with Lessee’s leasehold interest under the Lease. If, notwithstanding the intention of the parties and the economic realities of this Lease, this Lease is deemed to create a security interest, Lessee shall be deemed to have granted to Lessor as security for Lessee’s obligations hereunder, a first priority security interest in the Equipment and all proceeds thereof. Until Lessee’s obligations under each Schedule are satisfied in full, if requested by Lessor or if required by Applicable Law, Lessee shall at Lessee’s sole cost and expense permanently affix and maintain on any or all Equipment or as many items as required, as determined by Lessor or as required by Applicable Law, a sign, legend, plate, plaque, tag or other identifying label in a prominent place that discloses Lessor’s ownership or that such Equipment is leased from Lessor under such Schedule.

(b) Lessee further acknowledges that at least one of the following is true: (i) Lessee has selected the Supplier (as defined in Article 2A of the UCC), has directed Lessor to purchase the Equipment from the Supplier and has been informed by Lessor in writing (and is so hereby informed) that (A) Lessee is entitled under Article 2A of the UCC to certain rights under the Supply Contract (as defined in Article 2A of the UCC), and (B) Lessee may contact the Supplier to receive an accurate and complete

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statement from the Supplier of any such rights and any disclaimers and limitations of them or of remedies; or (ii) Lessee has received, reviewed and approved a copy of the Supply Contract covering the Equipment purchased from the Supplier thereof for lease to Lessee. To the fullest extent permitted by Applicable Law, Lessee hereby waives any and all rights and remedies conferred upon lessees by Sections 2A-508 through 2A-522 of the UCC as currently in force on the date hereof or otherwise conferred upon Lessee by the UCC. Lessee further waives, to the extent permitted by Applicable Law notice of sale or other disposition of the Equipment.

Section 4 . Term, Rent Termination and Purchase Option

4.1 Lease Obligation; Term . The Term of each Schedule (the “ Term ”) will consist of: (a) the Initial Term set forth on the Schedule, if any; (b) the Base Term and (c) the Renewal Term. The “ Initial Term ” (if any) shall commence on the date set forth on the Schedule and end on the Base Term Commencement Date. The “ Base Term ” shall commence on the Base Term Commencement Date and, unless terminated or extended as provided herein, shall end on the same day of the month as the Base Term Commencement Date at the end of One Hundred Twenty (120) months. Any Renewal Term will be as set forth in Section 5.3 hereof.

4.2 Rent; Late Payments . Lessee hereby covenants, agrees, and promises to pay to Lessor quarterly Rent, in arrears, plus applicable Taxes as increased from time to time in the amounts and pursuant to the terms and conditions of the applicable Schedule. Unless otherwise directed by Lessor, Rent and other amounts payable hereunder shall be paid to Lessor in the manner set forth in the applicable Schedule or in such other manner as Lessor shall specify in writing from time to time. All amounts payable to Lessor hereunder for which a payment date is expressly set forth herein (including Rent) shall be payable without notice or written demand by Lessor. All amounts payable to Lessor hereunder for which no payment date is expressly set forth herein shall be payable on written demand by Lessor to Lessee. Payments which are due on a day which is not a Business Day shall be payable on the next succeeding Business Day. If any Rent payment or any other Obligation under this Lease is not received by Lessor when due, Lessee shall pay to Lessor, in addition to such Rent or other payment, late fees on such amounts from the date due until payment is received by Lessor equal to the lesser of (a) five percent (5%) per annum on such amount (it being understood and agreed by the parties that such percentage shall be applied based on a calendar year of 365 days, with the interest on any given day being 1/365 of the total interest for the calendar year); and (b) the highest charge allowed by Applicable Law. The Lessee shall pay the reasonable expenses of Lessor (including fees and out-of-pocket expenses of Lessor’s attorneys and Lessor’s engineer) incurred at the request of Lessee, or in the performance of its duties under any of the Lease Documents, or in connection with any litigation which may at any time be instituted involving the Equipment or the Lease Documents, or in the pursuit of any remedies under the Lease Documents.

4.3 Termination . Each Lease shall terminate upon the earlier of (a) the end of the Term; or (b) the date upon which Lessor or Lessee terminates the Lease pursuant to any terms hereunder. No termination (whether by default or the passage of time) shall affect or impair the rights, powers or privileges of Lessor or the liabilities of Lessee relating to (i) any transaction or event occurring prior to the effective date of such termination or (ii) any of the undertakings, agreements, covenants, indemnifications, representations or warranties of Lessee contained in the Lease Documents. All such undertakings, agreements, covenants, indemnities, representations, and warranties of Lessee shall survive such termination and Lessor shall retain all of its rights and remedies under the Lease Documents.

4.4 Noncancellable; Absolute and Unconditional . Lessee agrees that each Schedule shall be NON-CANCELABLE and that Lessee’s obligation to pay any and all amounts due under the terms of each such Schedule promptly when due is ABSOLUTE AND UNCONDITIONAL, shall not be subject to cancellation, termination, modification or repudiation by Lessee, and shall be paid and performed by

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Lessee without notice or demand and without any abatement, reduction, diminution, setoff, defense, counterclaim or recoupment whatsoever, including: (i) any past, present or future claims that Lessee may have against Lessor, Vendor, any Permitted User or performance of any services relating to, any Equipment or any other part of the Equipment, or any other Person whatsoever; (ii) any defect in the title, condition, design, or operation of, or lack of fitness for use of, or any damage to, or loss of, all or any part of the Equipment or part of the Equipment from any cause; (iii) the existence of any Liens on the Equipment or any other part of the Equipment; (iv) the invalidity, unenforceability or disaffirmance of this Lease or any other Lease Document; (v) the prohibition of or interference with the use or possession by Lessee of all or any part of the Equipment or any other part of the Equipment, for any reason whatsoever, including by reason of: (A) claims for patent, trademark or copyright infringement; (B) present or future governmental laws, rules or orders; (C) the insolvency, bankruptcy or reorganization of any Person; and (D) any other cause whether similar or dissimilar to the above, any present or future law to the contrary notwithstanding (each, an “ Abatement ”). In no event will Lessee’s obligations under this Lease be excused or suspended by reason of strikes, embargoes, riot, war, acts of hostility, storm, fire, earthquake, acts of God or any other cause or event including frustration of purpose, impracticability or impossibility. Lessee may not cancel this Lease, and unless expressly provided otherwise herein or in the applicable Schedule, Lessee may not make any full or partial prepayments with respect to sums due hereunder.

Section 5 . Lessee Options

5.1 Early Buyout Option . Lessor hereby grants to Lessee the option, exercisable only as provided herein, to purchase all but not less than all Equipment leased pursuant to each Schedule prior to the expiration of the Term for such Schedule, subject to the following: (a) so long as no Event of Default, or event which with notice, lapse of time or both would become an Event of Default shall have occurred, Lessee shall have the right at its option to purchase all, but not less than all, Equipment leased pursuant to each Schedule (the “ EBO Equipment ”) on the Fifth (5th) and Seventh (7th) anniversaries of the Base Term Commencement Date (each an “ EBO Date ”); provided, however, that Lessee shall have given at least ninety (90) days but not more than one hundred fifty (150) days prior written notice (which notice shall be irrevocable without Lessor’s written consent) to Lessor; (b) on the EBO Date: (i) Lessee shall pay to Lessor an amount equal to: (A) Seventy-Five Percent (75%) of the Lessor’s Cost set forth on the Schedule in the event the EBO Date is the Fifth anniversary of the Base Term Commencement Date or Fifty-Six Percent (56%) of the Lessor’s Cost set forth on the Schedule in the event the EBO Date is the Seventh anniversary of the Base Term Commencement Date; plus (B) all other amounts due under such Schedule with respect to the EBO Equipment, including the Rent payment due on the EBO Date and applicable Taxes and other amounts due or payable with respect to such sale and (ii) Lessor shall sell such Equipment for cash to Lessee, AS IS, WHERE IS, without recourse or warranty (except that Lessor has whatever title (if any) to the Equipment that was conveyed to it by the Vendor free of any security interest arising solely by reason of a claim against Lessor that Lessee is not responsible to remove pursuant to this Lease). Provided that Lessee has complied with all obligations contained herein, such Schedule shall be deemed terminated on the EBO Date and Lessee shall have no further obligations to pay Rent thereunder. Notwithstanding anything to the contrary herein, Lessee hereby agrees that: (1) Lessee’s exercise of the Early Buyout Option under this Section 5.1 with respect to Equipment leased pursuant to one Schedule shall be automatically deemed to be an election of its Early Buyout Option to purchase all Equipment leased under all other Schedules to this Master Lease at the same EBO Date (Fifth or Seventh anniversary, as applicable) for such other Schedules in accordance with the terms thereof (which notice shall be irrevocable without Lessor’s written consent); and (2) if Lessee elects not to exercise its Early Buyout Option to purchase Equipment pursuant to this Section 5.1 on any EBO date with respect to any Schedule, it shall be deemed to have waived its rights to exercise its Early Buyout Option to purchase all Equipment leased under all other Schedules to this Master Lease on the same EBO Date.

5.2 Purchase Option . Provided that no Event of Default, and no event which with lapse of time or giving of notice or both would become an Event of Default, has occurred, Lessee may elect, by

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giving Lessor not less than one hundred eighty (180) days but not more than two hundred forty (240) days prior written notice (which notice shall be irrevocable without Lessor’s written consent), to purchase all, but not less than all, Equipment (the “ Purchased Equipment ”) as of the last day of the Base Term. In the event Lessee elects to purchase the Purchased Equipment from Lessor, it shall pay to Lessor on the date of expiration of the Base Term an amount equal to Twenty Four and Fifteen One-Hundredths Percent (24.15%) of the Lessor’s Cost set forth on the Schedule together with all other amounts due under such Schedule with respect to the Purchased Equipment plus applicable Taxes and other amounts due or payable with respect to such sale. All Purchased Equipment shall be sold to Lessee on an AS IS, WHERE IS BASIS, without recourse or warranty (except that Lessor has whatever title (if any) to the Equipment that was conveyed to it by the Vendor free of any security interest arising solely by reason of a claim against Lessor that Lessee is not responsible to remove pursuant to this Lease). Lessor and Lessee agree that the percentage multiplied by Lessor’s Cost in this Section 5.2 is a reasonable estimate of the fair market value of the Equipment at the end of the Base Term. Notwithstanding anything to the contrary herein, Lessee hereby agrees that: (a) Lessee’s exercise of its Purchase Option with respect to Equipment leased pursuant to one Schedule shall be automatically deemed to be an election of its option to purchase all Equipment leased under all other Schedules to this Master Lease at the end of the Base Term of such Schedules in accordance with the terms thereof (which notice shall be irrevocable without Lessor’s written consent); and (b) if Lessee elects not to exercise its Purchase Option right with respect to any Schedule, it shall be deemed to have waived its rights to exercise its option to purchase all Equipment leased under all other Schedules to this Master Lease.

5.3 Renewal Option .

(a) Provided that no Event of Default, and no event which with lapse of time or giving of notice or both would become an Event of Default has occurred, Lessee shall have the option, exercisable upon not less than one hundred eighty (180) days but not more than two hundred forty (240) days prior written notice (which notice shall be irrevocable without Lessor’s written consent), to extend the Base Term for an additional period of Sixty (60) months (the “ Renewal Term ”). During the Renewal Term, all of the terms and provisions of this Lease, shall continue to apply provided, however that quarterly Rent shall be adjusted at the beginning of the Renewal Term to equal the Fair Market Rental Value at such time. As used herein, the term “ Fair Market Rental Value ” means the rental value of the Equipment as determined on the basis of, and will be equal in amount to, the value which one would obtain in an arm’s-length transaction between an informed and willing lessee-user (other than a lessee currently in possession and a used equipment dealer) and an informed and willing lessor under no compulsion to lease and, in such determination it will be assumed that the Equipment is in the condition required to be maintained and returned under this Lease and is value on an installed basis and the costs of removal from current location shall not be a deduction from such valuation. For purposes of this Master Lease, the Fair Market Rental Value for the Equipment shall be determined by mutual agreement of Lessor and Lessee. If such mutual agreement cannot be reached, then it shall be determined by the Appraisal Process. If Fair Market Rental Value is not determined by the end of the Base Term, the Base Term shall, at Lessor’s election, be extended at the current Rental amount until Fair Market Rental Value is calculated as provided herein. At the end of the Renewal Term, Lessee shall comply with the provisions of this Lease regarding return or purchase of the Equipment.

(b) Notwithstanding anything to the contrary herein, Lessee hereby agrees that: (i) Lessee’s exercise of its Renewal Option with respect to Equipment leased pursuant to one Schedule shall be automatically deemed to be an election of its Renewal Option with respect to all Equipment leased under all other Schedules to this Master Lease at the end of the Base Term of such Schedules in accordance with the terms thereof (which notice shall be irrevocable without Lessor’s written consent); and (ii) if Lessee elects not to exercise its Renewal Option with respect to any Schedule, it shall be deemed to have waived its rights to exercise its Renewal Option with respect to all Equipment leased under all other Schedules to this Master Lease.

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5.4 Return of Equipment

(a) Unless Lessee purchases the Equipment, if allowed in accordance with the terms hereof: (i) Lessee shall be obligated to return the Equipment to Lessor at the end of the Term or as required by Lessor upon the occurrence of an Event of Default under Section 15.2; and (ii) Lessee shall at its sole expense demobilize, load, and transport the Equipment to any location in the Continental United States designated by Lessor such that possession is delivered to Lessor on the last day of the Term or immediately upon the occurrence of an Event of Default; provided, however, that if the location specified by Lessor is outside of the Return Radius from the Property where the Equipment was located pursuant to the applicable Permitted Use Agreement (the “ Site Location ”), Lessor shall pay that portion of the actual transportation costs which exceeds the transportation costs which would have been incurred by Lessee in transporting the Equipment a distance equal to the maximum Return Radius. As used herein the “ Return Radius ” shall mean the number of miles from the Vendor’s location from which the Equipment was originally delivered to the Site Location.

(b) Any and all components of the Equipment returned to Lessor shall be in the same physical and mechanical condition as originally delivered (except for Reasonable Wear and Tear) and in Average Saleable Condition. For purposes of this Lease “ Reasonable Wear and Tear ” shall mean: (i) the results of normal use of the Equipment as originally intended assuming use and maintenance in accordance with the Vendor’s recommendations and the complete absence of any casualty, misuse, abuse, abandonment, improper care, accident, negligence or similar occurrence with respect to the Equipment, whether or not the Equipment is in use at the time of said occurrence; and (ii) use that does not, in any way, impair the function of the Equipment or prevent the Equipment from promptly being placed into use. For purposes of this Lease “ Average Saleable Condition ” shall mean such condition that: (A) all components have at least a fifty (50%) remaining life until the next scheduled overhaul; (B) the Equipment has been properly operated and maintained in accordance with prudent industry practice; (C) the Equipment operates at its rated horsepower, temperature, pressure, fuel consumption, capacity, and efficiency and energy requirement, Reasonable Wear and Tear excepted; and (D) in accordance with any additional return requirements set forth in the applicable Schedule.

(c) If Lessee is required to return the Equipment in accordance with the terms hereof, Lessee shall provide Lessor, at Lessee’s sole cost and expense at least ninety (90) days prior to the end of the Term (or immediately if the Equipment is returned due to an Event of Default), with a true, accurate and complete set of all material documentation for the Equipment setting forth a detailed description of its components and its operating and maintenance history, all in form reasonably satisfactory to Lessor. Lessee shall also, at its sole expense (but not to exceed $250.00 per compressor package) at least sixty (60) days prior to the end of the Base Term (or the Renewal Term if Lessee has exercised its Renewal Option) have an authorized manufacturers’ representative, or other person approved in advance in writing by Lessor, review each compressor package’s operating and maintenance history and, if requested by Lessor, conduct various field tests to confirm that natural gas compressor packages constituting the Equipment is in Average Saleable Condition. Lessor shall also have the right to make such inspections and tests as it deems necessary or desirable to determine if the Equipment is in conformance with the requirements listed in this Section 5.4.

(d) Lessor shall indicate its approval or rejection of the condition of the returned Equipment by having its authorized representative sign and deliver to Lessee the Form Acceptance upon Return. If the Equipment does not meet the physical and/or mechanical requirements set forth above, then Lessee is to make the necessary corrections specified on the Form Acceptance upon Return within thirty (30) days (during which time Rent shall accrue and become due). Once such corrections are satisfactorily made by Lessee as evidenced solely by Lessor’s execution of the acceptance portion of the Form Acceptance upon Return, the subject Equipment will be deemed accepted by Lessor for purposes of in this Section 5.4. If the Equipment is not in the condition required, Lessee shall pay to Lessor, on demand, all costs, and

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expenses incurred by Lessor to bring the Equipment into the required condition. Lessee expressly agrees that, in the event Lessee does not elect to purchase the Equipment in accordance with the terms hereof, Lessor has the right to arrange for the sale or other disposition prior to the Equipment’s return (provided that such sale shall not close until the end of the applicable Term) and Lessee agrees to facilitate any such sale or disposition of the Equipment and that Lessor, its agents or employees, shall have the right to enter the Property for the purpose of showcasing the Equipment for sale or other disposition.

(e) Any entrance on the Property for inspection, showcasing or other purposes under this Section 5.4 shall be conducted in accordance with the provisions of Section 7.3(b) hereof.

Section 6 . Warranty Disclaimer; Selection; Additional Disclaimers and Waivers

6.1 Warranty Disclaimer; No Representations . LESSOR DOES NOT MAKE ANY, AND HEREBY DISCLAIMS, EACH AND EVERY, WARRANTY OR REPRESENTATION, EITHER EXPRESS OR IMPLIED, AS TO: (A) THE MERCHANTABILITY OR FITNESS OF THE EQUIPMENT OR ANY OTHER PART OF THE EQUIPMENT FOR ANY PARTICULAR PURPOSE; (B) THE QUALITY, THE CAPACITY OF THE EQUIPMENT OR THE WORKMANSHIP OF THE EQUIPMENT OR THE ABILITY OF THE EQUIPMENT, OR ANY PORTION THEREOF TO SATISFY THE REQUIREMENTS OF ANY LAW, RULE, SPECIFICATIONS OR CONTRACT THAT MAY BE APPLICABLE THERETO OR AS TO TITLE TO THE EQUIPMENT OR ANY COMPONENT OR ITEM THEREOF; AND (C) THE LEGAL, TAX OR ACCOUNTING TREATMENT OF THE TRANSACTIONS CONTEMPLATED HEREBY. IT IS AGREED THAT ALL SUCH RISKS, AS BETWEEN LESSOR, ON THE ONE HAND, AND LESSEE, ON THE OTHER HAND, ARE TO BE BORNE BY LESSEE AT ITS SOLE RISK AND EXPENSE.

6.2 Selection; Additional Waivers; Purchase Agreements .

(a) Lessor shall have no responsibility or liability to Lessee or any other Person with respect to any of the following, regardless of any active or passive negligence of Lessor: (i) any liability, loss or damage caused or alleged to be caused directly or indirectly by any part of the Equipment or by any inadequacy thereof or caused or alleged to be caused directly or indirectly by any part of the Equipment or by any inadequacy thereof or deficiency or defect therein or by any other circumstance in connection therewith; (ii) the transportation, ownership, possession, use, construction, operation, performance, maintenance, storage, repair, reconstruction or return of any part of the Equipment or any risks relating thereto; (iii) any interruption of service, loss of business or anticipated profits or consequential damages. Lessee further acknowledges and agrees that (A) it has selected the Equipment and each and every part thereof and has not relied on any representation or warranty by Lessor in connection with such selection; (B) Lessor is not the manufacturer of the Equipment or any component of the Equipment; (C) the Equipment and all other components of the Equipment are, and will be upon execution by Lessee of the applicable Schedule, of a size, design and make selected by Lessee, suitable for Lessee’s purposes, containing all safety features deemed necessary by Lessee, (D) Lessor is not an agent of Vendor or supplier of any part of the Equipment or any services in connection therewith or any party representing or acting on behalf of any of the foregoing and no such parties are agents of Lessor or otherwise authorized to bind Lessor to any representation, warranty or agreement; and (E) Lessor disclaims, and Lessee hereby waives, any right to seek or recover from Lessor any punitive, consequential or incidental damages which might be alleged to arise from a breach of this Lease, any assignment of this Lease, the delivery or use of the Equipment or any other claim which might be made by Lessee or its assigns against Lessor.

(b) Lessee agrees that: (i) each Purchase Agreement shall identify Lessor as the Person with the right to purchase the Equipment pursuant to the applicable Purchase Agreement, the right to take title to such Equipment and the right to be named as the purchaser in the bill of sale for such Equipment; and (ii) each Purchase Agreement, or the bill of sale for such Equipment to be issued to Lessor in accordance with

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the terms thereof, shall afford Lessor the benefits of all warranty and indemnity provisions contained in any such Purchase Agreement. Notwithstanding anything to the contrary contained herein, Lessor shall have no liability under any Purchase Agreement, shall not be obligated to perform any of the obligations or duties of Lessee under any Purchase Agreement and shall not be obligated to make any payment thereunder for the benefit of Lessee (other than under the terms and conditions set forth in this Lease). Each Purchase Agreement shall be acceptable to Lessor and Lessee will have no right to bind Lessor to any change in the Purchase Agreement, any delivery schedule, or any other agreement whatsoever and Lessee not shall not change any Purchase Agreement without Lessor’s prior written consent. So long as Lessee is not in default hereunder, Lessor hereby appoints and constitutes Lessee as its agent and attorney-in-fact during the term of this Lease to assert and enforce from time to time, for the account of Lessor, at Lessee’s sole cost and expense, whatever claims and rights Lessor may have against any Vendor for breach of warranty.

Section 7 . Possession, Maintenance and Use

7.1 Maintenance and Use of Equipment . Lessee, at its expense, shall maintain the Equipment in good operating order, repair and condition and shall perform maintenance on the Equipment and other components of the Equipment at least as frequently as set forth in any applicable operator’s guide, service manual and/or lubrication and maintenance guide for the Equipment. Lessee covenants and agrees that: (a) it shall use, operate, maintain or store the Equipment properly, carefully, safely or in accordance with: (i) all Applicable Laws or regulations of any Governmental Authority; (ii) all instructions, warranty provisions, operating manuals prepared or released by the Vendor and any manufacturer, supplier or maintenance organization for the Equipment, including any service agreement; (iii) all requirements of insurance maintained hereunder; and (iv) all Permits and Related Rights; and (b) it will not: (i) permit the Equipment to be used for any purpose other than in the conduct of its business; (ii) abandon the Equipment; (iii) permit the use of the Equipment to be changed from that specified herein; (iv) permit any Equipment to be removed from the location set forth on the Schedule as the location of the Equipment without the prior written consent of Lessor; (v) create, incur or allow to exist any Lien on any of its rights hereunder or to the Equipment except for Liens granted to Lessor pursuant to the Lease Documents; or (vi) permit the Equipment to be operated Persons other than Persons who are well-trained, competent and have sufficient experience and training to operate the Equipment satisfactorily and correctly; (c) the ordinary maintenance and repairs performed by Lessee pursuant to any provisions of this Lease will not change the purpose or character of the Equipment or materially enhance its value (as opposed to preserving its value or slowing its depreciation); (d) at the end of the Term, the Equipment can be removed from the location in which it will be used by Lessee and the use of the Equipment by a Person other than Lessee or an affiliate of Lessee will be commercially feasible, assuming normal market conditions; (e) the Rent does not materially exceed the Fair Market Rental Value of the Equipment; (f) to the best of Lessee’s knowledge, pursuant to general business practices, it is not unusual or extraordinary for property the same as, or similar to, the Equipment to be the subject of a lease for use similar to the use intended by Lessee; (g) Lessee shall keep accurate records of (i) all inventory and supplies used in connection with the operation of the Equipment or stored at the Equipment (including any solvents, lubricants or Hazardous Materials), (ii) the operations of the Equipment, and (iii) the occurrence of any event that may reasonably be considered to violate a Environmental Law or result in Environmental Loss, and provide copies of such written records to Lessor within five (5) days of Lessor’s written request; and (h) Lessee (or a designee approved by Lessor) shall be the sole operator of the Equipment and Lessor shall not have any obligation or responsibility to operate the Equipment or with respect to any designee approved by Lessor.

7.2. Alterations to Equipment . Provided that no Event of Default exists under this Lease and no event which with lapse of time or giving of notice or both would become an Event of Default, Lessee may at its sole cost and expense make any alterations, additions, repairs, modifications or attachments (“ Improvements ”) to the Equipment or any other part of the Equipment provided that Lessee notifies

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Lessor in advance of such action in writing (except in those cases where Lessee must make emergency or other immediate Improvements to preserve or return the Equipment to operational status or comply with Applicable Law, in which case advance notice shall not be required and Lessee shall notify Lessor as soon as is practicable after making such Improvements) and provided further that such Improvements, in Lessor’s judgment: (a) do not reduce the value or general usefulness of any part of the Equipment; (b) do not impair the certification, performance, safety, quality, capability, use or character of any part of the Equipment, or alter the purpose for which such Equipment was leased under this Lease; (c) do not expose Lessor or any part of the Equipment to any Lien; (d) do not adversely affect insurance coverage benefiting Lessor; (e) are of a kind that customarily are made by lessees or purchasers of Equipments similar to the Equipment; and (f) will not cause the Equipment to become limited use property within the meaning of Revenue Procedure 76-30 or materially reduce its general usefulness. If no Event of Default has occurred and is continuing and such Improvements are readily removable without causing material damage to the Equipment, Lessee shall have the right to remove any Improvements at its own expense prior to the return of the Equipment to Lessor, provided that removal will not impair its originally intended function or use. If any Improvements are not readily removable without causing material damage to the Equipment (or if removable but not removed by Lessee as when returned to Lessor), such Improvement shall automatically and without payment by Lessor become the property of Lessor subject to all provisions of this Lease.

7.3 Inspection .

(a) Lessor and its agents shall have the right at Lessee’s sole expense to inspect the Equipment, observe its use and inspect any information, written or otherwise, relating to it and to perform due diligence examinations and audit Lessee not to exceed four times in any calendar year; provided that Lessor is not obligated to do so and provided, further, that no restrictions on how frequently Lessor may conduct such inspections shall be applicable if a default or Event of Default shall have occurred and then be continuing. Lessor assumes no responsibility and waives no rights as a result of any inspection or observation or the lack thereof.

(b) So long as no default or Event of Default shall have occurred and then be continuing: (i) Lessor shall provide Lessee with reasonable advance notice of such inspections; (ii) such inspections shall occur only at reasonable times during usual business hours; and (iii) Lessee shall have the right to have its representatives present during any such inspections or other entry on the Property by Lessor, and Lessor shall not enter the Property without having a Lessee representative present.

7.4 Personal Property . The Equipment shall remain personal property regardless of its use or manner of attachment to the Property. The Lessee recognizes that the Equipment and any improvements represented thereby are removable and separable from, and not essential to, the Property and recognizes the right of Lessor to remove any portion of the Equipment and each Permitted Use Agreement shall contain similar statements from the applicable Permitted Users in form and substance satisfactory to Lessor.

Section 8 . Representations, Warranties and Covenants .

8.1 Representations and Warranties . In order to induce Lessor to enter into this Lease, Lessee represents and warrants the following to Lessor as of the date of this Master Lease and as of the date of each and every Schedule entered into pursuant hereto unless otherwise stated herein:

(a) Lessee is a limited liability company duly organized, validly existing and in good standing under the laws of the State of Delaware and is duly licensed or qualified to transact business in all other jurisdictions where the character of the property owned or leased or the nature of the business transacted by it makes such licensing or qualification necessary.

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(b) To the Best of Lessee’s Knowledge, Parent is a master limited partnership duly organized, validly existing and in good standing under the laws of the State of Delaware and is duly licensed or qualified to transact business in all other jurisdictions where the character of the property owned or leased or the nature of the business transacted by it makes such licensing or qualification necessary. As used herein in this Section 8, “ To the Best of Lessee’s Knowledge ” shall mean that no President or Vice President is aware of any facts that would give such Person actual knowledge or actual notice, and that no such Person has any current actual knowledge or current actual notice, that any such representations or warranties are false. For the avoidance of doubt the term “To the Best of Lessee’s Knowledge” shall not include or in any way required any inquiry or other investigation on the part of Lessee or any of its officers, employees, agents or other representatives.

(c) Lessee has all requisite power and authority, corporate or otherwise, and is duly authorized and empowered to: (i) enter into, execute, deliver and perform all of its Obligations under the Lease Documents; (ii) conduct its business as presently conducted; and (iii) own and operate its property and to operate the Equipment. The execution, delivery and performance by Lessee of this Lease and each of the other Lease Documents and the leasing hereunder have been duly authorized by all necessary action and do not and will not (A) require any consent or approval of additional members of Lessee or any authorization, consent or approval by any Governmental Authority, commission, board, bureau, agency or instrumentality, domestic or foreign, (B) violate any provision of any Applicable Law, rule or regulation or of any order, writ, injunction or decree presently in effect having applicability to Lessee or of the formation or governing documents of either such entity, (C) result in a breach of or constitute a default under any indenture or loan or credit agreement (including any such agreements in effect as of the date hereof between Lessee and any bank) or any other agreement, lease or instrument to which Lessee is a party or by which Lessee or its property may be bound or affected (except for those with Persons who have consented in writing thereto with copies of such consents delivered to Lessor), which breach or default would reasonably be expected to have a material adverse effect as described in Section 15.1(j), or (D) To the Best of Lessee’s Knowledge, result in a breach of or constitute a default under any indenture or loan or credit agreement (including any such agreements in effect as of the date hereof between Parent and any bank) or any other agreement, lease or instrument to which Parent is a party or by which Parent or its property may be bound or affected (except for those with Persons who have consented in writing thereto with copies of such consents delivered to Lessor).

(d) This Lease is, and each of the other Lease Documents to which Lessee is a party, when delivered will be, a legal, valid, and binding obligation of Lessee enforceable against such entity in accordance with their respective terms.

(e) No fact is known to Lessee that has had or can reasonably be expected in the future to have a material adverse effect on the business, property or financial condition of Lessee (or, To the Best of Lessee’s Knowledge, Parent) which has not been previously disclosed to Lessor by Lessee.

(f) As of the date of this Master Lease, the assets of Lessee are not subject to any Lien or the terms of any security agreement other than: (i) any Lien in favor of Lessor pursuant to the Lease Documents; (ii) any inchoate Lien incurred in the ordinary course of business that Lessee intends to remove in due course and (iii) any Liens set forth in that certain Fourth Amended and Restated Credit Agreement, dated as of December 1, 2004, among Regency Gas Services, LP, Parent and other parties set forth therein.

(g) Lessee is not in default in any material respect in the performance, observance or fulfillment of any indenture, loan or credit agreement, or to any lease or other agreement or instrument material to Lessee’s business to which it is a party or otherwise bound including this Lease or any other Lease Documents.

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(h) To the Best of Lessee’s Knowledge, Parent is not in default in any material respect in the performance, observance or fulfillment of any indenture, loan or credit agreement, or to any lease or other agreement or instrument material to Parent’s business to which it is a party or otherwise bound.

8.2 Covenants, Representations and Warranties . In order to induce Lessor to enter into this Lease, Lessee covenants, represents, warrants and agrees as of the date of this Master Lease and for the entire Term of each and every Schedule entered into pursuant hereto:

(a) All Financial Statements heretofore and hereafter furnished to Lessor present fairly in all material respects the financial condition of Lessee on the dates thereof and the results of Lessee’s operations for the periods then ended, and were prepared in accordance with GAAP. There are no liabilities of Lessee, fixed or contingent, which are material and are not reflected in the Financial Statements or the notes thereto, other than liabilities arising in the ordinary course of business since the date of the most recent Financial Statement. The Financial Statements do not contain any untrue statement of a material fact or omit a material fact necessary to make the statements contained herein or therein not misleading. Lessee shall at all times keep its books and records in accordance with GAAP. Lessor shall have access to the segment information for Lessee included in the public filings of the financial information filed by the Parent in accordance with Applicable Laws of the U.S. Securities and Exchange Commission. Lessee shall deliver, within thirty (30) days of issue, to Lessor its un-audited, internally generated, quarterly financial statements which are intended for internal use only.

(b) There has been no change in the business, assets, liabilities, business prospects, property, or condition (financial or otherwise) of Lessee (or, To the Best of Lessee’s Knowledge, Parent) which would have a material adverse effect on the business, property, or financial condition of Lessee since the date of the most recent Financial Statements.

(c) All information supplied to Lessor by Lessee (or on behalf of Lessee at Lessee’s direction) with respect to any assets or other properties of Lessee (whether prior to or subsequent to execution of this Lease), is and shall be true and correct in all material respects.

(d) To the Best of Lessee’s Knowledge, all information supplied to Lessor by Lessee (or on behalf of Lessee at Lessee’s direction) with respect to any assets or other properties of Parent (whether prior to or subsequent to execution of this Lease), is and shall be true and correct in all material respects.

(e) Lessee, in the conduct of all of its business affairs, has complied and will continue to comply in all material respects with the requirements of all Applicable Laws, including all Environmental Laws, the noncompliance with which would have a material adverse effect on the business, property or financial condition of Lessee and the ability of Lessee to perform under the Lease Documents. There have been no citations, notices, or orders of noncompliance (that have not been complied with or withdrawn) issued to Lessee under any Applicable Law which would have a material adverse effect on the business, property, or financial condition of Lessee. Lessee has, and is in good standing with respect to, all governmental consents, approvals, authorizations, permits, certificates, inspections and franchises necessary to continue and to conduct in all material respects such entity’s business as heretofore conducted (or proposed to be conducted) by it and to own or lease and operate in all material respects its properties as now owned or leased by it.

(f) Lessee represents and warrants that none of (i) the ownership, leasing or operation of the Equipment, (ii) the sale or use of electricity, steam or other outputs therefrom or (iii) the consummation of any transaction under this Lease or any of the other Lease Documents will cause Lessee to become subject to regulation under (A) the Public Utility Holding Company Act of 1935, as amended from time to time (“ PUHCA ”) as a “public-utility company,” a “holding company,” or an “affiliate” or “subsidiary company” of a “holding company” or of a “public utility holding company,” as those terms are used in PUHCA, or (B) the Federal Power Act, other than regulation with respect to which the Federal Energy Regulatory Commission, or any successor agency or commission thereto, may grant a waiver or pre-approval in an order authorizing Lessee to sell power.

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(g) Lessee has satisfied all judgments and Lessee is not in default in any material respect with respect to any judgment, writ, injunction, decree, rule, or regulation of any court, arbitrator, Governmental Authority, commission, board, bureau, agency, or instrumentality, domestic or foreign.

(h) There are no actions, suits, investigations or proceedings (“ Litigation ”) pending or, to the knowledge of Lessee, threatened against or affecting Lessee or the properties of Lessee before any court or Governmental Authority, commission, board, bureau, agency or instrumentality, domestic or foreign, which, if determined adversely to Lessee, could have a materially adverse effect on the financial condition, properties or operations of Lessee or the ability of Lessee to perform hereunder, under any other the Lease Document. Lessee shall promptly notify Lessor in writing of the occurrence of any such Litigation after execution of the Master Lease.

(i) To the Best of Lessee’s Knowledge, there is no Litigation pending or threatened against or affecting Parent or the properties of Parent before any court or Governmental Authority, commission, board, bureau, agency or instrumentality, domestic or foreign, which, if determined adversely to Parent, could have a material adverse effect on the financial condition, properties or operations of Parent or Lessee or the ability of Lessee to perform hereunder, under any other the Lease Document. Lessee shall promptly notify Lessor in writing of the occurrence of any such Litigation after execution of the Master Lease, but only in the event that Lessee acquires knowledge or notice or becomes aware of any such Litigation with respect to Parent or Parent’s properties and such knowledge, notice or awareness meets the definition of the term “To the Best of Lessee’s Knowledge” 8.1(b) above.

(j) Lessee possesses all material licenses, permits, franchises, patents, copyrights, trademarks and trade names or rights thereto, including all Permits and Related Rights, to conduct its business substantially as now conducted and as presently proposed to be conducted, and Lessee is not in violation of any valid rights of others with respect to any of the foregoing.

(k) Lessee has filed or caused to be filed all tax returns which are required to be filed by it pursuant to all applicable federal, state and local laws, regulations or orders. Lessee has paid, or made provision for the payment of, all Taxes which have or may have become due pursuant to said returns or otherwise or pursuant to any assessment received by Lessee or Parent. The charges, accruals, and reserves in respect of income taxes on the books of Lessee is adequate. Lessee knows of no proposed material Tax assessment against it and no extension of time for the assessment of federal, state or local Taxes of Lessee is in effect or has been required or applied for, except as disclosed in the Financial Statements.

Section 9 . Conditions Precedent . Any obligation of Lessor to lease the Equipment described in each Schedule shall be subject to the fulfillment to Lessor’s reasonable satisfaction of all of the following conditions as well as any additional conditions set forth in this Lease or any of the other Lease Documents and such other documents, certifications, or acknowledgments as Lessor shall reasonably request:

9.1 No Default . No Event of Default or event or condition that, with notice, lapse of time or both would become an Event of Default shall have occurred and be continuing;

9.2 Lease Documents . Lessor shall have received, in form and substance satisfactory to Lessor, the following items: (a) a fully executed and completed Schedule to which all exhibits, addenda and other attachments referenced therein are attached, which such Schedule shall contain any additional terms applicable to the Equipment and other portion of the Equipment leased thereunder; (b) evidence of Lessee’s insurance policies in accordance with Section 14 hereof with financially sound and reputable insurers, satisfactory to Lessor in its sole discretion; and (c) such other items as Lessor shall reasonably specify in this Lease or any Lease Documents.

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9.3 Permits and Related Rights . Lessee shall have obtained (and, if requested by Lessor, furnished to Lessor copies of) all Permits and Related Rights;

9.4 Organizational/Governing Documents; Existence and Good Standing . Lessor shall have received copies of the organizational and governing documents of Lessee that are certified by an authorized officer of Lessee, as applicable, as being true and correct copies thereof. Lessor shall have received a certificate of existence and good standing certificate with respect to Lessee, issued as of a recent date by the Secretary of State or other appropriate and authorized official of Lessee’s jurisdictions of organization and, if different, a good standing certificate issued with respect to Lessee as of a recent date by the Secretary of State or other appropriate and authorized official of the jurisdiction where the Equipment shall be located;

9.5 Title; Precautionary Lien Priority; No Liens . Lessor shall have received evidence that: (i) upon paying the purchase price of the Equipment to the Vendor, Lessor shall have good title, free of Liens and a precautionary first priority security interest in such Equipment; and (ii) placement of such Equipment at the location set forth on the Schedule will not cause any Lien in favor of any Person other than Lessor to attach to such Equipment.

9.6 Lessee’s Authorization . Lessee shall have provided in form and substance satisfactory to Lessor: (i) properly certified resolutions of Lessee’s manager, managing member or other governing body duly authorizing the execution and delivery of all Lease Documents to which it is a party; and (ii) such other authorizations and other documents as Lessor in its sole discretion may require;

9.7 Financial Statements . Lessor shall have received all financial statements required under Section 10(a);

9.8 Representations and Warranties . All representations and warranties herein shall be true and correct in all material respects as of such date, or to the extent they relate to an earlier date such representations and warranties shall be true and correct in all material respects as of such earlier date and Lessor shall have received a signed copy of a certificate in a form shown on Exhibit D of an authorized officer of Lessee certifying as to the foregoing;

9.9 No Material Adverse Change . There shall not have occurred any material adverse change in the business, assets, liabilities (actual or contingent), operations or condition (financial or otherwise) of the Lessee or, in the facts and information regarding Lessee as represented to date. The determination of what shall constitute a material adverse change shall be at Lessor’s sole reasonable discretion.

9.10 Payment of Fees and Expenses . Lessee shall have paid to Lessor all fees and expenses specified in this Lease as may then be due and payable;

9.11 Permitted Use Agreement; Access .

(a) Lessor shall have approved the Permitted Use Agreement related to the applicable Equipment and shall have received such documentation as Lessor reasonably requires to assure it of access to the Property for purposes of inspection and enforcement of its rights hereunder upon the occurrence of an Event of Default.

(b) Notwithstanding Section 9.11(a) hereof, Lessor agrees that Lessee may enter into one or more Schedules with respect to Equipment (“ Uncommitted Equipment ”) that is not subject to a Permitted Use Agreement at the time the Schedule is executed so long as: (i) the total Lessor’s Cost of all Uncommitted Equipment does not at any time exceed Seven Million Five Hundred Thousand Dollars ($7,500,000); (ii) any Uncommitted Equipment is stored at a location acceptable to Lessor; (iii) Lessee will take all action reasonably requested by Lessor to assure that the Equipment will not be sold or encumbered by any Lien including marking such Equipment conspicuously as property of Lessor; (iv)

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Lessee shall be diligently pursuing a Permitted Use Agreement for such Equipment; and (v) no such Schedule reduces the Fleet Utilization Rate or Equipment Utilization Rate below the amount permitted under Section 10.2 hereof. Upon Lessor’s written approval of a Permit