Document:

<PAGE>

                                                                 EXHIBIT 10.BB.4

                            LIMESTONE ELECTRON TRUST

                   THIRD AMENDED AND RESTATED TRUST AGREEMENT

                                       BY

                            WILMINGTON TRUST COMPANY,
                     as Trustee and Securities Intermediary

                              EL PASO CORPORATION,
                        as holder of the El Paso Interest

                                 ELECTRON TRUST,
                            as sole Certificateholder

                                       AND

                            LIMESTONE ELECTRON TRUST

                           Dated as of April 12, 2002

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                                TABLE OF CONTENTS

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                                                                                                           Page Nos.
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ARTICLE I  GENERAL................................................................................................2
         Section 1.01.  Appointment of Wilmington Trust Company...................................................2
         Section 1.02.  Formation of the Trust....................................................................2
         Section 1.03.  Name, Principal Office, and Name and Address of Trustee as
                          Agent for Service of Process............................................................2
         Section 1.04.  Purpose and Powers........................................................................2
         Section 1.05.  Claims Against the Trust..................................................................4
         Section 1.06.  Beneficial Ownership......................................................................4
         Section 1.07.  Certain Covenants Relating to the Separateness of the Trust...............................5

ARTICLE II  DEFINITIONS...........................................................................................7

ARTICLE III  CONTRIBUTIONS.......................................................................................10
         Section 3.01.  Initial Contribution.....................................................................10
         Section 3.02.  Contributions by the Certificateholders..................................................10
         Section 3.03.  Contributions by the Holder of the El Paso Interest......................................11
         Section 3.04.  Holding of the Trust Estate..............................................................12
         Section 3.05.  Limitation on the Liability of the Depositor and the
                          Certificateholders.....................................................................12

ARTICLE IV  THE LIMESTONE CERTIFICATES...........................................................................12
         Section 4.01.  Ownership................................................................................12
         Section 4.03.  Form of Certificates; Denominations; Yield...............................................12
         Section 4.04.  Execution of Certificates................................................................13
         Section 4.05.  Registration of Issuance, Transfer and Exchange of Limestone
                          Certificates...........................................................................13
         Section 4.06.  Mutilated, Destroyed, Lost or Stolen Certificates........................................15
         Section 4.07.  Persons Deemed Owners....................................................................15
         Section 4.08.  Access to List of Certificateholders' Names and Addresses................................16
         Section 4.09.  Maintenance of Office or Agency..........................................................16
         Section 4.10.  Limestone Certificates Held by El Paso...................................................16
         Section 4.11.  ERISA Information........................................................................16
         Section 4.12.  FERC Information.........................................................................16

ARTICLE V  THE EL PASO INTEREST..................................................................................17
         Section 5.01.  The El Paso Interest.....................................................................17
         Section 5.02.  Execution of El Paso Interest............................................................17
         Section 5.03.  Transfer of El Paso Interest.............................................................17
         Section 5.04.  Rights of Holder of El Paso Interest.....................................................17

ARTICLE VI  COLLECTIONS; DISTRIBUTIONS...........................................................................18
         Section 6.01.  Payments From Trust Estate...............................................................18
</Table>

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         Section 6.02.  Establishment of Limestone Distribution Account and Limestone
                          Collection Account.....................................................................18
         Section 6.03.  Distributions from the Limestone Distribution Account....................................21
         Section 6.04.  Distributions from the Limestone Collection Account......................................22
         Section 6.05.  Limestone Distribution Date Statements...................................................23
         Section 6.06.  Withholding..............................................................................23
         Section 6.07.  Information Provided by the Trustee......................................................24

ARTICLE VII  LIMESTONE CERTIFICATE TRIGGER EVENTS; SPECIFIED EQUITY EVENTS; LIMESTONE
                     CERTIFICATE PURCHASE RIGHT; CERTIFICATE PURCHASE OPTION; EARN-OUT PERIOD;
                     CANCELLATION OF LIMESTONE CERTIFICATES......................................................26
         Section 7.01.  Consequences of a Limestone Certificate Trigger Event or Specified Equity Event..........26
         Section 7.02.  Limestone Certificate Purchase Right; Certificate Purchase Option........................26
         Section 7.03.  Earn-Out Period..........................................................................27
         Section 7.04.  Cancellation of Limestone Certificates...................................................28

ARTICLE VIII  RIGHTS, OBLIGATIONS, POWERS AND STATUS OF THE CERTIFICATEHOLDERS AND THE HOLDER
                     OF THE EL PASO INTEREST.....................................................................28
         Section 8.01.  Management of the Trust..................................................................28
         Section 8.02.  Bankruptcy, Dissolution or Termination of any Certificateholder..........................29
         Section 8.03.  Creditors of the Certificateholders......................................................29
         Section 8.04.  Certain Rights of the Majority Certificateholders........................................29
         Section 8.05.  Voting and Other Rights of the Holder of the El Paso Interest............................29

ARTICLE IX  CONCERNING THE TRUSTEE, THE SECURITIES INTERMEDIARY AND WILMINGTON TRUST COMPANY.....................30
         Section 9.01.  General..................................................................................30
         Section 9.02.  Acceptance of the Trust..................................................................32
         Section 9.03.  Authority and Duties of the Trustee......................................................32
         Section 9.04.  Representations and Warranties of Wilmington Trust Company...............................34
         Section 9.05.  Resignation of the Trustee...............................................................34
         Section 9.06.  Liability................................................................................35
         Section 9.07.  Indemnification..........................................................................35
         Section 9.08.  Fees and Expenses........................................................................36
         Section 9.09.  Litigation, Action Outside Delaware......................................................36
         Section 9.10.  Rights of the Securities Intermediary....................................................37
         Section 9.11.  Resignation; Appointment of Successor Securities Intermediary............................37
         Section 9.12.  Acceptance of Appointment by Successor Securities Intermediary...........................37
         Section 9.13.  Merger or Consolidation of Securities Intermediary.......................................37

ARTICLE X  DISSOLUTION, BANKRUPTCY AND LIQUIDATION OF THE TRUST..................................................38
         Section 10.01.  Dissolution of the Trust................................................................38
         Section 10.02.  Termination.............................................................................39
</Table>

                                       ii
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ARTICLE XI  NOTICES..............................................................................................39
         Section 11.01.  Notices.................................................................................39

ARTICLE XII  MISCELLANEOUS PROVISIONS............................................................................40
         Section 12.01.  Entire Agreement........................................................................40
         Section 12.02.  Governing Law...........................................................................40
         Section 12.03.  Severability of Provisions..............................................................41
         Section 12.04.  Amendment or Waiver; Effect on Agreement................................................41
         Section 12.05.  Binding Upon Assigns....................................................................41
         Section 12.06.  Survival................................................................................41
         Section 12.07.  Tax Characterization....................................................................41
         Section 12.08.  Counterparts............................................................................42
         Section 12.09.  Effectiveness...........................................................................42
</Table>

Exhibit A         Form of Limestone Certificate
Exhibit B         Form of Certificate of Holder of El Paso Interest
Exhibit C         Form of Investment Certificate

                                      iii
<PAGE>

                            LIMESTONE ELECTRON TRUST

                   THIRD AMENDED AND RESTATED TRUST AGREEMENT

                  This THIRD AMENDED AND RESTATED TRUST AGREEMENT (this
"Agreement") of Limestone Electron Trust, a Delaware statutory business trust
(the "Trust"), is made and entered into as of April 12, 2002 by WILMINGTON TRUST
COMPANY, a Delaware banking corporation (not in its individual capacity but
solely as trustee hereunder, the "Trustee", and as securities intermediary), EL
PASO CORPORATION (formerly El Paso Energy Corporation), a corporation organized
under the laws of Delaware, as holder of the El Paso Interest, ELECTRON TRUST, a
Delaware statutory business trust, as sole Certificateholder, and LIMESTONE
ELECTRON TRUST, the Delaware statutory business trust continued hereby.
Capitalized terms used herein but not defined in Article II hereof have the
meanings assigned to such terms in Annex A to the Participation Agreement dated
as of March 15, 2000, as amended, supplemented, amended and restated or
otherwise modified from time to time (the "Participation Agreement"), among the
Trust, Credit Suisse First Boston (USA), Inc., as successor to DLJ Inc., El
Paso, El Paso Chaparral Holding, El Paso Chaparral Holding II, El Paso
Chaparral, the Management Company, Chaparral, Mesquite, the Share Trust, the
Overfund Trust, Electron, Wilmington Trust Company and The Bank of New York, as
successor to United States Trust Company of New York (each, as defined in the
Participation Agreement).

                  WHEREAS, as of December 22, 1999, Wilmington Trust Company and
El Paso, as Depositor, entered into a Trust Agreement (the "Original Trust
Agreement");

                  WHEREAS, as of December 28, 1999, Wilmington Trust Company,
the Depositor and the Trust amended and restated the Original Trust Agreement in
its entirety (the "First Amended and Restated Trust Agreement");

                  WHEREAS, as of March 27, 2000, Wilmington Trust Company, El
Paso, as holder of the El Paso Interest, Electron, as sole Certificateholder,
and the Trust amended and restated the First Amended and Restated Trust
Agreement in its entirety (the "Second Amended and Restated Trust Agreement");

                  WHEREAS, as of March 27, 2002, Wilmington Trust Company and El
Paso, as holder of the El Paso Interest entered into an amendment to the Second
Amended and Restated Trust Agreement ("Amendment No. 1");

                  WHEREAS, Wilmington Trust Company, El Paso, the sole
Certificateholder and the Trust desire to amend and restate the Second Amended
and Restated Trust Agreement, as amended by Amendment No. 1, in its entirety to
become effective on and as of the Effective Date in accordance with Section
12.09;

                  NOW THEREFORE, in consideration of the premises and the mutual
covenants herein contained, the parties hereto agree that the Second Amended and
Restated Trust Agreement, as amended by Amendment No. 1, is hereby amended and
restated to read in its entirety as set forth herein:

                                       1
<PAGE>

                                    ARTICLE I

                                     GENERAL

                  Section 1.01. Appointment of Wilmington Trust Company.
Pursuant to the Original Trust Agreement, the Depositor appointed Wilmington
Trust Company as Trustee of the Trust effective as of December 22, 1999, to have
all the rights, powers and duties set forth therein and in the Act. Pursuant to
the First Amended and Restated Trust Agreement, the Depositor and Wilmington
Trust Company agreed that Wilmington Trust Company would continue to be the
Trustee of the Trust. Pursuant to the Second Amended and Restated Trust
Agreement, El Paso, all of the Certificateholders and Wilmington Trust Company
agreed that Wilmington Trust Company would continue to be Trustee of the Trust.
Pursuant to this Agreement, El Paso, all of the Certificateholders and
Wilmington Trust Company agree that Wilmington Trust Company shall continue to
be the Trustee of the Trust upon the terms and conditions set forth herein.

                  Section 1.02. Formation of the Trust. The Trust was formed and
continued as a statutory business trust under and pursuant to the Act, the
Original Trust Agreement and the Certificate of Trust of the Trust. It is the
intention of the parties hereto that this Agreement amend, restate and supersede
the Second Amended and Restated Trust Agreement, as amended by Amendment No. 1,
and from and after the Effective Date, constitute the sole governing instrument
of the Trust. All Persons owning or otherwise holding interests of beneficial
ownership in the Trust shall own or otherwise hold such interests of beneficial
ownership pursuant to the provisions of this Agreement.

                  Section 1.03. Name, Principal Office, and Name and Address of
Trustee as Agent for Service of Process. The Trust shall continue to be
conducted under the name "Limestone Electron Trust," in which name the Trust or
the Trustee on behalf of the Trust shall enter into contracts and agreements
with respect to the transactions contemplated hereby. The principal place of
business and office of the Trust shall be c/o Wilmington Trust Company, Rodney
Square North, 1100 North Market Street, Wilmington, Delaware 19890-0001,
Attention: Corporate Trust Administration. The Trustee, who is hereby designated
to accept service of process, shall continue to be Wilmington Trust Company and
its current office is located at the address provided in the preceding sentence.

                  Section 1.04. Purpose and Powers. (a) The purpose of the Trust
shall be limited to engaging in the following activities:

                  (i) entering into, complying with its obligations under,
consummating the transactions and engaging in the activities contemplated by,
(A) the Participation Agreement, (B) the Chaparral LLC Agreement (including
exercising its right to act as Managing Member of Chaparral in accordance with
the Chaparral LLC Agreement), (C) the Indenture, (D) the Security Agreement, (E)
the Remarketing Agreement, (F) this Agreement, (G) the Limestone Account Control
Agreement dated as of March 27, 2000 among the Trust, United States Trust
Company of New York, as indenture trustee, and Wilmington Trust Company, as
securities intermediary, (H) the Closing Agreement, (I) the New Indenture, (J)
the Dealer Manager Agreement and (K) any other Transaction Documents to which it
is to be a party;

                                       2
<PAGE>

                  (ii) (A) entering into any document necessary or appropriate
to commence and/or consummate the Exchange Offer and the transactions
contemplated thereby (including, without limitation, the Closing Agreement and
the Dealer Manager Agreement), (B) entering into any document necessary or
appropriate to amend, supplement or modify any Transaction Document to which the
Trust is a party or by which it is bound to the extent necessary or appropriate
to commence and/or consummate the Exchange Offer and the transactions
contemplated thereby and (C) undertaking any other action necessary or
appropriate to enter into, proceed with, effect and/or consummate the Exchange
Offer, in each case pursuant to the terms and conditions of the Offering
Circular and Consent Solicitation Statement;

                  (iii) owning all the outstanding shares of the Co-Issuer,
which shares shall be registered in the name of the Trust and held by the
Trustee on behalf of the Trust;

                  (iv) issuing the El Paso Interest to El Paso;

                  (v) issuing the Original Certificates pursuant to the First
Amended and Restated Trust Agreement, selling the Original Certificates, issuing
the Subsequent Certificates pursuant to the Second Amended and Restated Trust
Agreement and selling the Subsequent Certificates;

                  (vi) issuing, together with the Co-Issuer, (A) the Limestone
Notes pursuant to the Indenture and selling the Limestone Notes and (B) the New
Limestone Notes pursuant to the New Indenture in exchange for Limestone Notes;

                  (vii) assigning, granting, transferring, pledging, mortgaging
and conveying the Trust Estate to the Indenture Trustee for the benefit of the
holders of the Limestone Notes and holding, managing and distributing to the
Certificateholders and the holder of the El Paso Interest any portion of the
Trust Estate released from the Lien of, and remitted to the Trust pursuant to,
the Indenture in accordance with this Agreement;

                  (viii) making payments to the Indenture Trustee for the
benefit of the holders of the Limestone Notes pursuant to and in accordance with
the Indenture, making payments to the New Indenture Trustee for the benefit of
the holders of the New Limestone Notes pursuant to and in accordance with the
New Indenture and this Agreement (after the repayment in full of the Outstanding
Limestone Notes) and making distributions to the holders of the Limestone
Certificates and the holder of the El Paso Interest pursuant to and in
accordance with this Agreement;

                  (ix) notwithstanding any other provision hereof, repaying the
principal amount of the Limestone Loan with a portion of the proceeds from the
sale of the Limestone Notes and the Subsequent Certificates and paying all
accrued interest on the Limestone Loan with the proceeds of a distribution from
Chaparral, and discharging any obligations of the Trust under the Limestone
Credit Agreement, the security documents related thereto and the Assignment and
Assumption Agreement;

                  (x) (A) holding the Class A Member Interest and (B) upon (I)
the repayment of all of the Limestone Notes on the Maturity Date with Cash
contributed by the holder of the El Paso Interest pursuant to Section 3.03, (II)
the redemption of all or any portion of the Limestone

                                       3
<PAGE>

Notes pursuant to Section 14.01(a)(ii)(A) or 15.01(c)(i) of the Indenture, (III)
the redemption of all or any portion of the New Limestone Notes pursuant to
Section 14.01(a)(ii)(A) or 15.01(c)(i) of the New Indenture, or (IV) a payment
by El Paso, as Guarantor, pursuant to Section 3.09 of the New Indenture,
acquiring an Additional Class B Member Interest and being admitted to Chaparral
as a Class B Member pursuant to Section 3.2(b)(iii) of the Chaparral LLC
Agreement;

                  (xi) making an additional Cash Capital Contribution of
$1,027,250,000 to Chaparral to increase the Class A Member's Capital Account by
such amount;

                  (xii) receiving payments and other distributions from
Chaparral with respect to the Class A Member Interest and any Additional Class B
Member Interest;

                  (xiii) engaging in those activities that are necessary to
accomplish the foregoing or are incidental thereto;

                  (xiv) subject to compliance with the Transaction Documents,
engaging in such other activities as may be required in connection with
conservation of the Trust Estate and making distributions to the
Certificateholders and the holder of the El Paso Interest; and

                  (xv) executing and making, at the request of Chaparral, the
Overfund Trustee or the holder of the El Paso Interest, but at no cost to the
Trust, such filings and registrations, and taking such other actions, as may be
reasonably necessary or appropriate under Applicable Law, Contractual
Obligations to which the Trust is a party, or otherwise, to conduct the business
of Chaparral or its subsidiaries or to transfer member interests in Chaparral or
to comply with, or to consummate the transactions contemplated by, the
Transaction Documents to which the Trust is a party.

                  (b) The Trust is hereby authorized to engage in the foregoing
activities. The Trust shall not engage in any activity other than (i) the
activities described in clause (a) above or (ii) subject to the terms of this
Agreement, as the Certificateholders and, where appropriate, the holder of the
El Paso Interest, may from time to time direct.

                  Section 1.05. Claims Against the Trust. All Persons extending
credit to, contracting with or having any claim against the Trust shall look
only to the Trust for payment under such credit, contract or claim. None of the
Trustee (including in its individual capacity), the Depositor, the
Certificateholders, the holder of the El Paso Interest or any of the Trust's
officers, employees or agents, whether past, present or future, shall be
personally liable therefor.

                  Section 1.06. Beneficial Ownership. The beneficial ownership
interests in the Trust will be evidenced by (i) the Limestone Certificates
issued on December 28, 1999 pursuant to the First Amended and Restated Trust
Agreement and exchanged for new Limestone Certificates on March 27, 2000
pursuant to the Second Amended and Restated Trust Agreement, (ii) the Limestone
Certificates issued in accordance with Article IV of the Second Amended and
Restated Trust Agreement and (iii) the El Paso Interest issued on December 28,
1999 pursuant to the First Amended and Restated Trust Agreement, each of which
shall constitute undivided beneficial interests in the Trust Estate, provided,
that the rights of the holder of the El Paso Interest are limited as set forth
in Sections 5.04 and 8.05.

                                       4
<PAGE>

                  Section 1.07. Certain Covenants Relating to the Separateness
of the Trust. The Trust shall maintain its separate existence and, specifically,
shall conduct its affairs in accordance with, and El Paso agrees that it will
not take any actions in its dealings with the Trust that are inconsistent with,
the following:

                  (a) The Trust shall: (i) maintain and prepare separate
financial reports (if any) and financial statements (if any) in accordance with
GAAP, showing its assets and liabilities separate and apart from those of any
other Person (other than the Co-Issuer), and will not have its assets listed on
the financial statement of any other Person (provided, however, that the Trust's
assets may be included in a consolidated financial statement of the
Certificateholders if inclusion on such consolidated financial statement is
required to comply with the requirements of GAAP, but only if (a) such
consolidated financial statement shall be appropriately footnoted to the effect
that the Trust's assets are owned by the Trust and that they are being included
on the consolidated financial statement of the Certificateholders solely to
comply with the requirements of GAAP, and (b) such assets shall be listed on the
Trust's own separate balance sheet); (ii) maintain its books, records and bank
accounts separate from those of its Affiliates, any constituent party and any
other Person; and (iii) not permit any Affiliate or constituent party (other
than the Trustee in its capacity as Trustee) independent access to its bank
accounts.

                  (b) The Trust shall not commingle or pool any of its funds or
other assets with those of any Affiliate or constituent party or any other
Person, and it shall, through the Trustee, hold all of its assets in its own
name, except as provided in the Indenture.

                  (c) The Trust, through the Trustee, shall conduct its own
business in its own name and shall not operate, or purport to operate,
collectively as a single or consolidated business entity with respect to any
Person (other than the Co-Issuer).

                  (d) The Trust shall, insofar as is consistent with commercial
and business circumstances affecting its business and financial condition,
remain solvent and pay its own debts, liabilities and expenses (including
overhead expenses, if any) only out of its own assets as the same shall become
due (other than, if at all, pursuant to Section 6.06 and except for certain
legal fees, accounting fees and other out-of-pocket costs and expenses incurred
by the Trust in connection with the formation, administration and activities of
the Trust, which items may be paid by the holder of the El Paso Interest or an
Affiliate of the holder of the El Paso Interest, and except for certain costs
and liabilities of the Trust indemnified against by the holder of the El Paso
Interest pursuant to the Transaction Documents) (provided, that this covenant
shall not constitute a guaranty or "keep well" obligation by the Trustee, any
administrator of or with respect to the Trust or any other Person in respect of
the Trust or its debts, liabilities or expenses, or any financial or balance
sheet condition or ratio of or relating to the Trust).

                  (e) The Trust has done, or caused to be done, and shall do,
all things necessary to observe all Delaware statutory business trust
formalities and other organizational formalities, and preserve its existence
(subject to Article X and the other express provisions hereof), and it shall
not, nor will it permit any Affiliate or constituent party to, amend, modify or
otherwise change this Agreement in a manner which would adversely affect the
existence of the Trust as a special purpose entity.

                                       5
<PAGE>

                  (f) The Trust shall not have any employees.

                  (g) The Trust does not, and shall not, (i) guarantee, become
obligated for, or hold itself or its credit out to be responsible for or
available to satisfy, the debts or obligations of any other Person or (ii)
control the decisions or actions respecting the daily business or affairs of any
other Person.

                  (h) The Trust shall, to the extent it utilizes stationery,
invoices and checks, maintain and utilize separate stationery, invoices and
checks bearing its own name.

                  (i) The Trust shall, at all times, hold itself out to the
public as a legal entity separate and distinct from any other Person and shall
correct any known misunderstanding regarding its separate identity.

                  (j) The Trust shall not identify itself as a division of any
other Person.

                  (k) The Trust shall maintain its assets in such a manner that
it will not be costly or difficult to segregate, ascertain or identify its
individual assets from those of any Affiliate, constituent party or any other
Person, except as provided in the Indenture.

                  (l) The Trust shall not use its separate existence to abuse
creditors or to perpetrate a fraud, injury, or injustice on creditors in
violation of Applicable Law.

                  (m) The Trust shall not, in connection with the Transaction
Documents, act with an intent to hinder, delay, or defraud any of its creditors
in violation of Applicable Law.

                  (n) The Trust shall not be consensually merged or legally
consolidated with any other Person (other than certain Affiliates for financial
reporting and federal tax purposes), but without prejudice to the right to
dissolve, liquidate or wind up in accordance with its Organizational Documents
or Applicable Law.

                  (o) The Trust's ability to enter into transactions with
Affiliates is limited only to transactions on an arms' length basis and on
commercially reasonable terms (the parties hereto each agreeing that the
Transaction Documents satisfy the aforementioned standard).

                  (p) The Trust shall not acquire Equity Interests of any
Affiliate (except Chaparral and the Co-Issuer).

                  (q) The Trust shall not incur any Relevant Indebtedness other
than any Relevant Indebtedness incurred in connection with or pursuant to the
Transaction Documents.

                  (r) The Trust shall not make loans or advances to any Person,
other than pursuant to Section 6.06 and except as permitted by the Transaction
Documents.

                  (s) The issuance of the Limestone Certificates and the El Paso
Interest to the Certificateholders and the holder of the El Paso Interest,
respectively, was and is intended to be, and shall be accounted for on the
books, records, and financial statements of the Trust, the Certificateholders
and the holder of the El Paso Interest, as applicable, as the issuance of equity

                                       6
<PAGE>

capital and not as a loan by the Certificateholders and the holder of the El
Paso Interest, as applicable, to the Trust.

                  (t) The Trust shall make no transfer of its assets except in
accordance with the Transaction Documents.

                  (u) The Trust shall not pledge its assets for the benefit of
any Person, except pursuant to the Transaction Documents.

                  (v) The Trust shall not, nor will it permit any Affiliate or
constituent party to, amend this Section 1.07 in a manner which would adversely
affect the existence of the Trust as a special purpose entity.

                                   ARTICLE II

                                   DEFINITIONS

                  "Amendment No. 1" has the meaning set forth in the preliminary
statements hereto.

                  "Available Funds" means, with respect to any Limestone
Distribution Date, the aggregate amount of Cash on deposit in the Limestone
Distribution Account or the Limestone Collection Account, as the case may be.

                  "Bankruptcy Action" has the meaning set forth in Section
10.01.

                  "Benefit Plan Investor" means a "benefit plan investor" as
defined in the Plan Asset Regulations.

                  "Certificate Face Amount" means, with respect to each
Limestone Certificate, the portion of the aggregate face amount of Limestone
Certificates outstanding corresponding to such Limestone Certificate.

                  "Certificate of Trust" means the Certificate of Trust of the
Trust filed under the Act with the Secretary of State on December 22, 1999, as
such Certificate of Trust may be amended or restated from time to time.

                  "Certificate Purchase Option" has the meaning assigned to such
term in Section 7.02(b).

                  "Certificate Record Date" has the meaning set forth in Section
6.03(d).

                  "Certificate Register" has the meaning set forth in Section
4.05(a).

                  "Certificate Registrar" has the meaning set forth in Section
4.05(a).

                                       7
<PAGE>

                  "Certificateholder" means, with respect to any date, the
Person or Persons in whose name Limestone Certificates (other than Limestone
Certificates that have been cancelled or deemed cancelled pursuant to Section
7.04) are registered in the Certificate Register.

                  "Competitor of El Paso" means any Person who conducts any
significant operations in energy and energy related businesses, including
businesses relating to Energy Assets, except for Persons whose primary business
is banking, insurance, investment banking, investment management or other
investing and financial services.

                  "Depositor" means El Paso, as depositor pursuant to the
Original Trust Agreement.

                  "El Paso Interest" means the Class B beneficial ownership
interest in the Trust issued and authenticated pursuant to the First Amended and
Restated Trust Agreement.

                  "EP Purchase Option Deposit Amount" has the meaning set forth
in Section 7.02(a).

                  "Equity Event Notice" has the meaning set forth in Section
6.07(g).

                  "First Amended and Restated Trust Agreement" has the meaning
set forth in the preliminary statements hereto.

                  "Indemnified Trustee Person" has the meaning set forth in
Section 9.07.

                  "Limestone Certificate Purchase Right" has the meaning set
forth in Section 7.02(a).

                  "Limestone Collection Account" has the meaning set forth in
Section 6.02.

                  "Limestone Distribution Account" has the meaning set forth in
Section 6.02.

                  "Limestone Distribution Date" means each Business Day on which
there are Available Funds in the Limestone Distribution Account or the Limestone
Collection Account; provided that after the satisfaction and discharge of the
Indenture and the New Indenture, "Limestone Distribution Date" shall mean
"Distribution Date" as defined in Annex A.

                  "Limestone Distribution Date Statement" has the meaning set
forth in Section 6.05.

                  "Majority Certificateholders" means at any time
Certificateholders holding, collectively, Limestone Certificates evidencing more
than 50% of the aggregate Certificate Face Amount of all Limestone Certificates
outstanding. At any time when there are no Certificateholders, the holder of the
El Paso Interest shall constitute the "Majority Certificateholders."

                                       8
<PAGE>
                  "Original Certificates" means the Limestone Certificates
issued on December 28, 1999 pursuant to the First Amended and Restated Trust
Agreement having an original Certificate Face Amount, in the aggregate, of
$50,000,000.

                  "Operating Account" means Limestone's account (account number
49273-0) at Wilmington Trust Company.

                  "Periodic Filings" means any tax filings or submissions that
the Trust is required to make with any Federal, state or local taxing authority
or regulatory agency.

                  "Plan Asset Regulations" means the U.S. Department of Labor
regulations at 29 C.F.R. Section 2510.3-101, as in effect from time to time.

                  "Proportionate Interest" at any time, means the proportion
that each Certificateholder's Certificate Face Amount bears to the aggregate
Certificate Face Amount of the Limestone Certificates.

                  "PTP Relevant Person" means each Tax Matters Representing
Purchaser and each Indirect Tax Matters Representing Purchaser that, in each
case, is able to make the representations described in clauses (B)(1) or (B)(2)
of the definition of Tax Matters Representing Purchaser.

                  "Required Certificateholders" means at any time
Certificateholders holding, collectively, Limestone Certificates evidencing more
than 25% of the aggregate Certificate Face Amount of all Limestone Certificates
outstanding. At any time when there are no Certificateholders, the holder of the
El Paso Interest shall constitute the "Required Certificateholders."

                  "Second Amended and Restated Trust Agreement" has the meaning
set forth in the preliminary statements hereto.

                  "Secretary of State" means the office of the Secretary of
State of the State of Delaware.

                  "Subsequent Certificates" means the $100,000,000 aggregate
Certificate Face Amount of Limestone Certificates issued on the Closing Date
pursuant to the Second Amended and Restated Trust Agreement.

                  "Tax Matters Representing Purchaser" means a Person that is
able to represent that (A) it is acting for its own account and not as the
nominee or agent of any other Person, (B) either (1) it is not a partnership,
grantor trust, or S corporation for United States Federal income tax purposes (a
"Flowthrough Entity"), (2) it is a Flowthrough Entity, but less than 50% of the
assets of the Flowthrough Entity will be represented, directly or indirectly, by
Limestone Certificates or (3) it is a Flowthrough Entity (x) whose nominal
owners are able to make the representations in (A) and either (B)(1) or (B)(2)
or, (y) to the extent that any of its direct or indirect nominal owners cannot
make the representations in (B)(1) or (B)(2) and is itself a Flowthrough Entity
(an "Upper Tier Flowthrough Entity"), the nominal owners of any such Upper Tier
Flowthrough Entity are able to make the representations in (A) and either (B)(1)
or

                                       9
<PAGE>

(B)(2) (each such nominal owner described in clause (3) that makes the
representations in either (B)(1) or (B)(2), an "Indirect Tax Matters
Representing Purchaser"), and (C) it has not acquired, and will not transfer any
Limestone Certificates (or any derivative interest therein) on or through an
established securities market within the meaning of Section 7704(b)(1) of the
Code (and Treasury regulations thereunder).

                  "Trust" means the Delaware statutory business trust known as
"Limestone Electron Trust" which was formed on December 22, 1999, under the Act
pursuant to the Original Trust Agreement and the filing of the Certificate of
Trust and continued pursuant to the First Amended and Restated Trust Agreement,
the Second Amended and Restated Trust Agreement, as amended by Amendment No. 1,
as amended and restated by this Agreement.

                  "Trust Estate" means all right, title and interest of the
Trust in, to and under the Class A Member Interest, any Additional Class B
Member Interest, any Transaction Document to which the Trust is a party
(including all rights of the Trust to any amounts payable to the Trust under any
Transaction Document) and any other property contributed to the Trust or
otherwise acquired by the Trust, together with all distributions, payments,
revenues, issues, profits or proceeds thereof and therefrom, and all
appurtenances thereto.

                  "Trustee" means Wilmington Trust Company, not in its
individual capacity but solely as a trustee hereunder, and any successor trustee
appointed in accordance with Section 3807 of the Act and Section 9.05.

                  The rules of construction set forth in Annex A to the
Participation Agreement shall apply to this Agreement as if set forth herein.

                                   ARTICLE III

                                  CONTRIBUTIONS

                  Section 3.01. Initial Contribution. On December 22, 1999, the
Depositor assigned, transferred, conveyed and set over to the Trustee the sum of
one dollar, which initial contribution shall constitute part of the Trust
Estate.

                  Section 3.02. Contributions by the Certificateholders. (a) On
December 28, 1999, Electron purchased the Original Certificates for $50,000,000,
which contribution constituted (and shall continue to constitute) a part of the
Trust Estate and was used by the Trust to make a Capital Contribution to
Chaparral to increase the Class A Member's Capital Account by such amount.

                  (b) Each Certificateholder purchasing Subsequent
Certificates, simultaneously with the delivery thereto of a Limestone
Certificate issued by the Trust in accordance with the provisions of the Second
Amended and Restated Trust Agreement, paid to the Trust or the account
designated by the Trust an amount equal to the applicable Certificate Face
Amount, which contribution on the Closing Date constituted a part of the Trust
Estate and was used by the Trust to make an additional Capital Contribution to
Chaparral to increase the Capital Account of the Trust, as Class A Member of
Chaparral.

                                       10
<PAGE>

                  (c) Reserved.

                  (d) The Certificateholders may, at any time and from time
to time, contribute Cash to the Trust for the purpose of causing an Optional
Redemption of all or a portion of the Limestone Notes or, if such contribution
occurs following a Limestone Note Trigger Event but prior to the Asset Remedy
Standstill Expiration Date, a Mandatory Redemption of all of the Limestone
Notes. The Trustee shall, immediately upon its receipt of any such contribution,
irrevocably deposit such contribution into the Indenture Collection Account with
the Indenture Trustee to cause (a) an Optional Redemption of all or a portion of
the Limestone Notes pursuant to and in accordance with Section 14.01(a)(ii)(B)
of the Indenture or (b) a Mandatory Redemption of all of the Limestone Notes
pursuant to and in accordance with Section 15.01(c)(ii) of the Indenture.

                  Section 3.03. Contributions by the Holder of the El Paso
Interest.

                  (a) The holder of the El Paso Interest may, at any time
and from time to time, contribute Cash to the Trust for the purpose of causing
(x) an Optional Redemption of all or a portion of the Limestone Notes if no
Limestone Note Trigger Event has occurred, (y) if such contribution occurs prior
to the 120th day before the Maturity Date and no Limestone Note Trigger Event
has occurred, the repayment of the Limestone Notes on the Maturity Date, or (z)
if such contribution occurs following a Limestone Note Trigger Event but prior
to the Asset Remedy Standstill Expiration Date, a Mandatory Redemption of all of
the Limestone Notes. Simultaneously with such contribution, if made prior to the
occurrence of a Limestone Note Trigger Event, the holder of the El Paso Interest
shall notify the Trustee and the Indenture Trustee in writing as to the purpose
to which such contribution is to be applied. The Trustee shall, immediately upon
its receipt of any such contribution, irrevocably deposit such contribution into
the Indenture Collection Account with the Indenture Trustee to cause (in
accordance with the notice received from the holder of the El Paso Interest, if
such contribution is received prior to the occurrence of a Limestone Note
Trigger Event) (a) an Optional Redemption of all or a portion of the Limestone
Notes pursuant to and in accordance with Section 14.01(a)(ii)(A) of the
Indenture, (b) repayment of the Limestone Notes on the Maturity Date in
accordance with Section 5.04(b) of the Indenture or (c) a Mandatory Redemption
of all of the Limestone Notes pursuant to and in accordance with Section
15.01(c)(i) of the Indenture.

                  (b) If any proceeds from the Asset Remedy, any Asset
Disposition or asset sales (in connection with an enforcement proceeding
following a judgment against the Issuers) are distributed to the New Noteholders
pursuant to Section 5.04 of the New Indenture, the holder of the El Paso
Interest shall, no later than the earlier of (x) 12:00 noon New York City time
on the 10th Business Day following the repayment in full of the New Limestone
Notes and (y) the occurrence of an "Event of Default" described in Section
7.1(e) of the June 11 Agreement with respect to El Paso, regardless of whether
notice is given by the Trustee under Section 6.07(f), contribute Cash to the
Trust for deposit into the Limestone Distribution Account in an amount equal to
the lesser of (i) the amount of such proceeds used to repay the New Limestone
Notes and (ii) the Certificate Purchase Amount as of such date (net of any funds
or the proceeds of the sale of any investments then held for the benefit of the
Limestone Certificateholders in the Limestone Distribution Account, Limestone
Collection Account or, to the extent such amounts

                                       11
<PAGE>

are available for distribution by the Indenture Trustee to Limestone for the
benefit of the Limestone Certificateholders under the Indenture, the Indenture
Accounts).

                  (c) Any payments by El Paso, as Guarantor, pursuant to
Section 3.09 of the New Indenture shall be deemed to constitute a contribution
by the holder of the El Paso Interest of Cash to the Trust in respect of the El
Paso Interest in the amount of such payment.

                  Section 3.04. Holding of the Trust Estate. In furtherance of
Sections 1.01 and 1.02, the Trustee hereby declares and agrees that it will hold
all estate, right, title and interest in and to the Trust Estate until this
Agreement terminates pursuant to the terms of this Agreement, in trust under and
subject to the conditions and agreements hereinafter set forth, for the use and
benefit of the Certificateholders from time to time and the holder of the El
Paso Interest.

                  Section 3.05. Limitation on the Liability of the Depositor and
the Certificateholders. None of the Depositor, any Certificateholder or the
holder of the El Paso Interest shall be liable for any debt, claim, demand,
judgment or obligation of any kind of, against or with respect to the Trust by
reason of its being the Depositor, a Certificateholder or the holder of the El
Paso Interest, nor shall the Depositor, any Certificateholder or the holder of
the El Paso Interest, by reason of its status as such, be subject to any
personal liability whatsoever, in tort, contract or otherwise, to any Person in
connection with the property, liabilities or affairs of the Trust.

                                   ARTICLE IV

                           THE LIMESTONE CERTIFICATES

                  Section 4.01. Ownership. (a) On December 28, 1999, the Trust
issued (i) the Original Certificates to Electron and (ii) the El Paso Interest
to El Paso, in accordance with the First Amended and Restated Trust Agreement.

                  (b) On the Closing Date, the Trust issued the Subsequent
Certificates to Electron in accordance with the Second Amended and Restated
Trust Agreement.

                  (c) The holders of the Limestone Certificates and the
holder of the El Paso Interest are the beneficiaries and beneficial owners
(within the meaning of the Act) of the Trust. All outstanding Limestone
Certificates shall share pari passu in the Trust Estate to the extent set forth
herein and any payments distributable to the Certificateholders therefrom, each
in accordance with its Proportionate Interest.

                  Section 4.02. Reserved.

                  Section 4.03. Form of Certificates; Denominations; Yield. The
Limestone Certificates shall be offered and sold in their initial distribution
to a number of institutions that are Qualified Purchasers that make the
representations set forth in Exhibit C hereto, in transactions exempt from
registration under the Securities Act, and shall be issued in definitive fully
registered form, without interest coupons, in substantially the form attached as
Exhibit A

                                       12
<PAGE>

hereto, with such applicable legends as are provided for in Exhibit A. The
Limestone Certificates shall be issued in minimum denominations of $100,000 and
integral multiples of $1,000 in excess thereof. The Limestone Certificates shall
be executed on behalf of the Trust by manual or facsimile signature of any
authorized signatory of the Trustee having such authority. Limestone
Certificates bearing the manual or facsimile signatures of individuals who were,
at the time when such signatures were affixed, authorized to sign on behalf of
the Trustee shall be validly issued and entitled to the benefits of this
Agreement, notwithstanding that such individuals or any of them have ceased to
be so authorized prior to the authentication and delivery of such Limestone
Certificates. The Limestone Certificates shall accrue yield as set forth in each
such Limestone Certificate.

                  Section 4.04. Execution of Certificates. No Limestone
Certificate shall entitle its holder to any benefit under this Agreement, or
shall be valid for any purpose, unless such certificate is executed by the
Trustee, by manual or facsimile signature. All Limestone Certificates shall be
dated the date of their execution. The Original Certificates and the Subsequent
Certificates shall be treated as a single class for all purposes under this
Agreement, including, without limitation, with respect to waivers, amendments,
redemptions and offers to purchase.

                  Section 4.05. Registration of Issuance, Transfer and Exchange
of Limestone Certificates. (a) The Certificate Registrar shall maintain, or
cause to be maintained, at the office or agency maintained pursuant to Section
4.09, a certificate register (the "Certificate Register") in which, subject to
such reasonable regulations as it may prescribe, the Trustee shall provide for
the registration of Limestone Certificates and of transfers and exchanges of
Limestone Certificates as provided in this Agreement. Pursuant to the Second
Amended and Restated Trust Agreement, Wilmington Trust Company was appointed
"Certificate Registrar" for the purpose of registering Limestone Certificates
and transfers and exchanges of Limestone Certificates as provided in this
Agreement.

                  (b) Upon surrender for registration of transfer of any
Limestone Certificate at the office or agency maintained pursuant to Section
4.09, the Trustee, on behalf of the Trust, shall execute and deliver, in the
name of the designated transferee or transferees, one or more new Limestone
Certificates in authorized denominations of a like Certificate Face Amount dated
the date of execution by the Trustee, subject to the applicable restrictions on
transfer set forth herein. At the option of a Certificateholder, the Limestone
Certificates may be exchanged for other Limestone Certificates in authorized
denominations of a like Certificate Face Amount upon surrender of the Limestone
Certificates to be exchanged at the office or agency maintained pursuant to
Section 4.09.

                  (c) Every Limestone Certificate presented or surrendered
for registration of transfer or exchange shall be accompanied by a written
instrument of transfer in form satisfactory to the Trustee and the Certificate
Registrar duly executed by the Certificateholder or its attorney duly authorized
in writing, including the representations set forth in Section 4.12. Each
Limestone Certificate surrendered for registration of transfer or exchange shall
be cancelled and subsequently disposed of by the Trustee in accordance with its
customary practice.

                                       13
<PAGE>

                  (d) No service charge shall be made for any registration of
transfer or exchange of Limestone Certificates, but the Trustee or the
Certificate Registrar may require payment of a sum sufficient to cover any tax
(other than income taxes) or governmental charge that may be imposed in
connection with any transfer or exchange of Limestone Certificates.

                  (e) Each Limestone Certificate shall be subject to the
restrictions on transfer provided in the applicable legends required to be set
forth in the face of each Limestone Certificate pursuant to Exhibit A hereto.
Whenever any Limestone Certificate is presented or surrendered to the Trustee
for registration of transfer or for exchange for a Limestone Certificate
registered in a name other than that of the Certificateholder, such Limestone
Certificate must be accompanied by, and each proposed transferee, as a condition
to the issuance to such transferee by the Trust of any Limestone Certificate,
shall deliver to the Trustee (A) an appropriately completed certificate of the
proposed transferee (an "Investment Certificate") substantially in the form set
forth in Exhibit C hereto to stating, among other things, (1) that such proposed
transferee is (x) a Qualified Purchaser that has acquired the Limestone
Certificates in compliance with the restrictions on transfer provided in the
applicable legends required to be set forth on the face of each Limestone
Certificate and (y) a Tax Matters Representing Purchaser, (2) that the
representations set forth in Section 4.12 are true and correct with respect to
such proposed transferee, (3) whether the proposed transferee is (x) a Benefit
Plan Investor (and/or if such proposed transferee is an insurance company and it
is using assets of its general account to acquire such Limestone Certificates,
the proportion of its general account that constitutes plan assets for purposes
of the determination described in clause (A) of paragraph (f) below) and/or (y)
a Person who has discretionary authority or control with respect to the assets
of the Trust or provides investment advice with respect to such assets for a fee
(direct or indirect) or an Affiliate of any such Person and (4) if the proposed
transferee is a Benefit Plan Investor subject to ERISA and/or Section 4975 of
the Code, that the transfer will not result in a non-exempt prohibited
transaction within the meaning of Section 406 or 407 of ERISA or Section 4975 of
the Code, and (B) a completed Tax Information Schedule (in the form attached to
the Investment Certificate) for itself and each of its direct or indirect
nominal owners that are Indirect Tax Matters Representing Purchasers. The
Trustee shall forward a copy of each Investment Certificate to the Depositor for
its records.

                  (f) No transfer of a Limestone Certificate shall be effective,
and the Trustee will not recognize any such transfer if, immediately after
giving effect to such transfer, (A) Limestone Certificates corresponding to 25%
or more (as determined under the Plan Asset Regulations) of (i) the aggregate
face amount of Limestone Certificates outstanding and (ii) any other beneficial
ownership interest in the Trust would be held by Benefit Plan Investors or (B)
there would be more than 99 PTP Relevant Persons. For purposes of making the
determination in clause (A) of the immediately preceding sentence, Limestone
Certificates held by or for the benefit of any Person (other than a Benefit Plan
Investor) that has discretionary authority or control over the assets of the
Trust or that provides investment advice for a fee (direct or indirect) with
respect to such assets, or an Affiliate of any such Person, shall be
disregarded.

                  (g) Unless and until (i) a Limestone Note Trigger Event has
occurred, (ii) a Specified Equity Event has occurred or (iii) the Earn-Out
Period Commencement Date has occurred, no Limestone Certificate may be
transferred (except in connection with the exercise of

                                       14
<PAGE>

the Limestone Certificate Purchase Right or the Certificate Purchase Option
hereunder or the Purchase Option under the Chaparral LLC Agreement) unless the
transferor provides the Trustee with a certificate of transfer stating that (x)
the transferee is not a Competitor of El Paso or (y) the consent of El Paso to
such transfer has been obtained.

                  (h) If the holder of the El Paso Interest or its designee or
assignee has given notice of the exercise of its rights under Section 7.02(a) or
(b) and has duly made the deposit of the EP Purchase Option Deposit Amount
referred to in Section 7.02, no transfer of a Limestone Certificate shall be
effective, and the Trustee shall not recognize any such transfer, unless the
holder of the El Paso Interest shall have given prior written consent to such
transfer.

                  (i) Notwithstanding anything contained herein to the contrary,
the Trustee shall not be responsible for ascertaining whether any transfer
complies with the registration provisions or exemptions from the PUHCA, the FPA,
the Securities Act, the Exchange Act, applicable state securities law or the
Investment Company Act; provided, however, that if a certificate is specifically
required to be delivered by the Trustee by a purchaser or a transferee of a
Limestone Certificate, the Trustee shall be obligated to examine such
certificate to determine whether it conforms to the requirements of this
Agreement.

                  Section 4.06. Mutilated, Destroyed, Lost or Stolen
Certificates. In case any Limestone Certificate becomes mutilated or defaced or
lost, destroyed or stolen, then on the terms herein set forth, and not
otherwise, the Trustee on behalf of the Trust shall execute, authenticate and
deliver to the registered Certificateholder a new Limestone Certificate of like
tenor and date, and bearing such identifying number or designation as the
Trustee may determine, in exchange and substitution for, and upon cancellation
of, the mutilated or defaced Limestone Certificate, or in lieu of and in
substitution for the same if lost, destroyed or stolen. The applicant for a new
Limestone Certificate pursuant to this Section 4.06 shall, in the case of any
mutilated or defaced Limestone Certificate, surrender such Limestone Certificate
to the Trustee and furnish to the Trustee, in the case of any lost, destroyed or
stolen Limestone Certificate, evidence satisfactory to the Trustee of such loss,
destruction or theft and, in each case, evidence satisfactory to the Trustee of
the ownership and authenticity of such Limestone Certificate and shall pay all
expenses and charges of such substitution and furnish such security or indemnity
as may be reasonably required by the Trustee to indemnify and defend and save
the Trustee and the Trust harmless (provided, that the unsecured agreement of
indemnity of any Certificateholder shall be deemed satisfactory, it being
understood, that the Trustee may reasonably request information necessary to
establish that any such holder is a Qualified Purchaser). Any defaced or
mutilated Limestone Certificate shall be destroyed by the Trustee, or retained
in accordance with its standard retention policy, upon delivery by it of a new
Limestone Certificate to the Certificateholder.

                  Section 4.07. Persons Deemed Owners. Prior to due presentation
of a Limestone Certificate for registration of transfer, the Trustee, the
Certificate Registrar, and any agent of the Trustee or the Certificate Registrar
may treat the Person in whose name any Limestone Certificate is registered as
the owner of such Limestone Certificate for the purpose of receiving
distributions pursuant to Section 6.03 and for all other purposes whatsoever,
and neither the Trustee, the Certificate Registrar, nor any agent of the Trustee
or the Certificate Registrar shall be affected by any notice to the contrary.

                                       15
<PAGE>

                  Section 4.08. Access to List of Certificateholders' Names and
Addresses. The Trustee shall furnish or cause to be furnished to each
Certificateholder or the holder of the El Paso Interest, within 15 days after
receipt by the Trustee of a written request therefor from such Certificateholder
or the holder of the El Paso Interest, a list, in such form as such party may
reasonably require, of the names and addresses of the Certificateholders as of
the most recent practicable date. Every Certificateholder, by receiving and
holding a Limestone Certificate, agrees that neither the Trustee nor any agent
thereof, shall be held accountable by reason of the disclosure of any such
information as to the names and addresses of the Certificateholders under this
Agreement, regardless of the source from which such information was derived.

                  Section 4.09. Maintenance of Office or Agency. The Trustee
shall maintain in Wilmington, Delaware, an office or offices or agency or
agencies where Limestone Certificates may be surrendered for registration of
transfer or exchange and where notices and demands to or upon the Trustee in
respect of the Limestone Certificates and the Transaction Documents may be
served. The Trustee initially designates Wilmington Trust Company, Rodney Square
North, 1100 North Market Street, Wilmington, Delaware 19890-0001 as its
principal corporate trust office for such purposes. The Trustee shall give
prompt written notice to the Certificateholders and the holder of the El Paso
Interest of any change in the location of the Certificate Register or any such
office of agency.

                  Section 4.10. Limestone Certificates Held by El Paso. For the
purposes of determining whether the Certificateholders of the requisite
Certificate Face Amount have taken any action authorized by this Agreement with
respect to the giving of instruction, consents or approvals or with respect to
any other matter, any Limestone Certificates actually known by a Responsible
Officer of the Trustee to be directly or indirectly owned by El Paso or any of
its Affiliates shall be disregarded and deemed not to be outstanding, unless El
Paso is the sole Certificateholder.

                  Section 4.11. ERISA Information For purposes of the
determination described in Section 4.05(f)(A), each Certificateholder that is an
insurance company will be required to promptly provide a written statement to
the Trustee setting forth (a) the then current proportion of its general account
that constitutes such plan assets and (b) other relevant information, in each
case, at any time requested by the Trustee in connection with a proposed
transfer or exchange of any Limestone Certificate and/or any proposed transfer
or exchange of any other beneficial ownership interest in the Trust. If so
requested by any Certificateholder or the holder of the El Paso Interest, the
Trustee shall request the statements referred to in the preceding sentence.
Promptly upon its receipt of any statement described in the second sentence of
this Section 4.11 or any Investment Certificate, the Trustee shall provide a
complete copy of such statement or certificate to the person making such request
and the Depositor.

                  Section 4.12. FERC Information. Each Certificateholder and any
transferee thereof will be required to provide a written statement to the
Trustee representing that:

                  (a) it is not in the business of producing, transmitting or
selling electric power;

                                       16
<PAGE>

                  (b) its principal business is other than that of a "public
utility" as that term is defined by Section 201 of the FPA and the orders of the
FERC interpreting such section; and

                  (c) it is not a "holding company" as that term is defined by
Section 2 of the PUHCA.

                                    ARTICLE V

                              THE EL PASO INTEREST

                  Section 5.01. The El Paso Interest. The El Paso Interest
represents an undivided, beneficial ownership interest in the Trust Estate;
provided, that the rights of the holder of the El Paso Interest are limited as
set forth in Sections 1.06, 5.04 and 8.05.

                  Section 5.02. Execution of El Paso Interest. On December 28,
1999, the Trustee issued and authenticated the El Paso Interest on behalf of the
Trust and delivered the certificate evidencing the El Paso Interest to El Paso.

                  Section 5.03. Transfer of El Paso Interest. The holder of the
El Paso Interest may not transfer or otherwise dispose of the El Paso Interest
without the consent of the Majority Certificateholders, except that no such
consent shall be required in connection with the transfer to a designee with
respect to, or an assignee of, the Limestone Certificate Purchase Right or the
Certificate Purchase Option. Each transferee of the El Paso Interest shall
deliver to the Trustee an appropriately completed certificate of the proposed
transferee substantially in the form set forth in Exhibit C (or in the case of
any transferee who is an Affiliate of El Paso, Exhibit B) hereto.

                  Section 5.04. Rights of Holder of El Paso Interest. (a) Until
the cancellation of all Limestone Certificates outstanding pursuant to Section
7.04, the El Paso Interest shall entitle the holder thereof only to the specific
voting rights set forth in Section 8.05 and to the Limestone Certificate
Purchase Right and the Certificate Purchase Option (and, in each case, rights of
designation and assignment with respect thereto), the other rights set forth in
Section 3.03, Section 8.05 and Article VII, and the right to receive
distributions in the circumstances set forth in Sections 5.04(b) and 5.04(c).
Notwithstanding the foregoing, the holder of the El Paso Interest shall have the
right to direct the Trustee to take any action required to be taken by Limestone
for El Paso to comply with El Paso's obligations under Section 5.1 of the
Participation Agreement. The holder of the El Paso Interest agrees to provide
the indemnities and defenses and pay the costs and expenses described in
Sections 9.07, 9.08 and 9.09.

                  (b) Immediately upon the cancellation or deemed cancellation
of all Limestone Certificates outstanding pursuant to Section 7.04, but not
before, the El Paso Interest shall be entitled to distributions from the Trust
as provided in Sections 6.03(a)(iv), 6.04(c)(v) and 10.01.

                  (c) Once (i) the holder of the El Paso Interest makes a
contribution pursuant to Section 3.03(a) and, as a result thereof, all or a
portion of the Limestone Notes have been

                                       17
<PAGE>

repaid or redeemed pursuant to the Indenture or (ii) the holder of the El Paso
Interest is deemed to make a contribution pursuant to Section 3.03(c) and all or
a portion of the New Limestone Notes have been repaid or redeemed pursuant to
the New Indenture, the El Paso Interest shall entitle the holder to the right to
receive all allocations and distributions to which the Additional Class B Member
Interest held by the Trust (pursuant to Section 3.2(b)(iii) of the Chaparral LLC
Agreement) is entitled under the Chaparral LLC Agreement; provided that no such
distribution shall be made to the holder of the El Paso Interest prior to the
cancellation or deemed cancellation of the Limestone Certificates pursuant to
Section 7.04.

                                   ARTICLE VI

                           COLLECTIONS; DISTRIBUTIONS

                  Section 6.01. Payments From Trust Estate. All payments to be
made by the Trustee on behalf of the Trust or otherwise under this Agreement or
any of the documents to which the Trust is a party shall be made only from the
income and proceeds of the Trust Estate or, in the event that the holder of the
El Paso Interest shall have made a contribution pursuant to Section 3.03 or the
Limestone Certificate Purchase Right or the Certificate Purchase Option shall
have been exercised by the holder of the El Paso Interest or its designee or
transferee, from the funds deposited with the Trustee in connection with such
contribution or exercise and only to the extent that the Trust shall have
received income or proceeds from the Trust Estate, or such deposit of a
contribution under Section 3.03 or the EP Purchase Option Deposit Amount,
respectively, as aforesaid, to make such payments in accordance with the terms
hereof.

                  Section 6.02. Establishment of Limestone Distribution Account
and Limestone Collection Account. (a)(i) The Securities Intermediary hereby
acknowledges and agrees that it has established, on the books and records of its
office in Delaware, the "Limestone Distribution Account" and the "Limestone
Collection Account" in the name of the Trust, each of which are under the
"control" (as defined in Sections 8-106 and 9-106 of the Delaware UCC) of the
Trust. In addition, the Securities Intermediary hereby agrees that (A) each of
the Limestone Distribution Account and the Limestone Collection Account is and
shall be maintained by the Securities Intermediary as, a "securities account"
(within the meaning of Section 8-501 of the Delaware UCC), (B) the "securities
intermediary's jurisdiction" (within the meaning of Article 8 of the Delaware
UCC) of the Securities Intermediary is the State of Delaware, (C) all cash and
other property in each of the Limestone Distribution Account and the Limestone
Collection Account will be treated by the Securities Intermediary as a
"financial asset" (as defined in Section 8-102(a)(9) of the Delaware UCC) for
the purposes of Article 8 of the Delaware UCC, (D) the "entitlement holder" (as
such term is defined in Section 8-102(a)(7) of the Delaware UCC) for the
purposes of Article 8 of the Delaware UCC shall be the Trust, and (E) the
Securities Intermediary shall act as a "securities intermediary" (within the
meaning of Section 8-102(a)(14) of the Delaware UCC) in maintaining the
Limestone Distribution Account and the Limestone Collection Account and shall
credit to each of the Limestone Distribution Account and the Limestone
Collection Account each financial asset to be held in or credited to each of the
Limestone Distribution Account and the Limestone Collection Account pursuant to
this Agreement. To the extent, if any, that the Trust is deemed to hold
directly, as opposed to having a security entitlement in, any financial asset
held by the Securities Intermediary for the Trust, the

                                       18
<PAGE>

Securities Intermediary hereby agrees that it is holding such financial asset as
the agent of the Trust and hereby expressly acknowledges and agrees that it has
received notification of the Trust's security interest in such financial asset
and that it is holding possession of such financial asset for the benefit of the
Trust.

                           (ii) Each of the Limestone Distribution Account and
         the Limestone Collection Account shall remain at all times with a
         securities intermediary (within the meaning of Section 8-102(a)(14) of
         the Delaware UCC) having a combined capital and surplus of at least
         $150,000,000 and having a long-term debt rating of at least "A3" by
         Moody's and at least "A-" by S&P or otherwise acceptable to such rating
         agencies. The Securities Intermediary shall give notice to the Trust of
         the location of the Limestone Distribution Account and the Limestone
         Collection Account and of any change thereof (provided that, subject to
         Section 9.10, no such change shall be made without the prior approval
         of the Trust), prior to the use thereof. Any income received by the
         Trust with respect to the balance from time to time on deposit in each
         of the Limestone Distribution Account and the Limestone Collection
         Account, including any interest or capital gains on investments in
         overnight securities made with amounts on deposit in each of the
         Limestone Distribution Account and the Limestone Collection Account,
         shall be credited to the Limestone Distribution Account or the
         Limestone Collection Account, as applicable. All right, title and
         interest in and to the cash amounts on deposit from time to time in
         each of the Limestone Distribution Account and the Limestone Collection
         Account together with any investments in overnight securities from time
         to time made pursuant to this Article VI shall constitute part of the
         Trust Estate and shall be held for the benefit of the Trust as its
         interests shall appear hereunder and shall not constitute payment of
         any obligations to which such funds are provided hereunder to be
         applied until applied thereto as hereinafter provided.

                           (iii) In the event that the Securities Intermediary
         has or subsequently obtains by agreement, operation of law or otherwise
         a security interest in the Limestone Distribution Account or the
         Limestone Collection Account, or any "financial asset" (as defined in
         Section 8-102(a)(9) of the Delaware UCC) credited thereto, or any
         "securities entitlement" (as defined in Section 8-102(a)(17) of the
         Delaware UCC) with respect thereto, the Securities Intermediary hereby
         agrees that such security interest shall be subordinate to the security
         interest of the Trust. The financial assets (as defined in Section
         8-102(a)(9) of the Delaware UCC) or any "securities entitlement" (as
         defined in Section 8-102(a)(17) of the Delaware UCC) with respect
         thereto, standing to the credit of the Limestone Distribution Account
         and the Limestone Collection Account will not be subject to deduction,
         set-off, banker's lien, or any other right in favor of any Person other
         than the Trust (except the face amount of any checks which have been
         credited to any of the Limestone Distribution Account or the Limestone
         Collection Account but are subsequently returned unpaid because of
         uncollected or insufficient funds).

                           (iv) There are no other agreements entered into
         between the Securities Intermediary and the Trust with respect to the
         Limestone Distribution Account and the Limestone Collection Account. In
         the event of any conflict between this Section 6.02(a) (or any portion
         thereof), any other provision of this Agreement or any other agreement
         now existing or hereafter entered into, the terms of this Section
         6.02(a) shall prevail.

                                       19
<PAGE>

                           (v) The Trustee shall make or direct the Securities
         Intermediary to make, to the extent required or authorized hereunder,
         withdrawals from each of the Limestone Distribution Account and the
         Limestone Collection Account: (i) to withdraw any amount deposited in
         each of the Limestone Distribution Account and the Limestone Collection
         Account and not required to be deposited therein; (ii) to make required
         payments to the parties entitled thereto pursuant to Sections 6.03 and
         6.04; and (iii) to clear and terminate each of the Limestone
         Distribution Account and the Limestone Collection Account pursuant to
         Article X.

                  (b) Unless otherwise instructed by the holder of the El Paso
Interest pursuant to Section 8.05(c) prior to the occurrence of an El Paso Debt
Obligation Repayment Event, the Trustee shall invest all funds deposited in the
Limestone Distribution Account (which shall be funds received from (i) the
Indenture Trustee pursuant to the Indenture, (ii) the New Indenture Trustee
pursuant to the New Indenture, (iii) El Paso pursuant to the Tax Indemnification
Agreement, (iv) Chaparral in respect of any Special Class A Tax Distribution
pursuant to Section 5.1(c) of the Chaparral LLC Agreement, (v) the holder of the
El Paso Interest or its designee or assignee pursuant to Section 7.02, (vi)
Chaparral in respect of the Additional Class B Member Interest, if any, held by
the Trust, (vii) the Remarketing Agents, El Paso or the Share Trust pursuant to
the Remarketing Agreement following the payment in full of the Limestone Notes,
(viii) the holder of the El Paso Interest pursuant to Section 3.03(b), (ix) the
Overfund Trust pursuant to Section 5.5(b) of the Participation Agreement upon
and after the discharge of the Indenture and (x) the Share Trust in respect of
any Redemption Proceeds pursuant to Section 4.03(a) of the Share Trust Agreement
following the payment in full of the Limestone Notes) in Financial Investments
consisting of overnight repurchase obligations for underlying securities of the
type described in clause (b) of the definition of Financial Investments that are
otherwise consistent with Financial Investments described in clause (d) of the
definition thereof until withdrawn in accordance with this Agreement. Only the
Trustee, on behalf of and for the benefit of the Trust, shall be entitled to
withdraw funds from the Limestone Distribution Account and only the Trustee
shall be an authorized signatory on the Limestone Distribution Account. The
Trustee shall withdraw funds from the Limestone Distribution Account only
pursuant to and in accordance with this Agreement.

                  (c) Unless otherwise instructed by the holder of the El Paso
Interest pursuant to Section 8.05(c) prior to the occurrence of an El Paso Debt
Obligation Repayment Event, the Trustee shall invest all funds deposited in the
Limestone Collection Account (which shall be funds received from (i) Electron in
respect of the Subsequent Certificates on the Closing Date, (ii) Chaparral in
respect of the Class A Member Interest (including in respect of any Additional
Financing Costs, any proceeds of the Asset Remedy, any proceeds of an Asset
Disposition or any proceeds of an asset sale (in connection with an enforcement
proceeding following a judgment against the Issuers) distributed to the holder
of the Class A Member Interest) other than any Special Class A Tax Distribution,
(iii) the Primary Class B Member or its designee or assignee, as Electing
Purchasers pursuant to Section 11.2 of the Chaparral LLC Agreement, (iv)
Chaparral pursuant to Section 11.1 of the Chaparral LLC Agreement, (v) the
Certificateholders pursuant to Section 3.02(d), and (vi) the holder of the El
Paso Interest pursuant to Section 3.03(a)) in Financial Investments consisting
of overnight repurchase obligations for underlying securities of the type
described in clause (b) of the definition of Financial Investments that are
otherwise consistent with Financial Investments described in clause (d) of the
definition thereof until

                                       20
<PAGE>

withdrawn in accordance with this Agreement. Only the Trustee, on behalf of and
for the benefit of the Trust, shall be entitled to withdraw funds from the
Limestone Collection Account and only the Trustee shall be an authorized
signatory on the Limestone Collection Account. The Trustee shall withdraw funds
from the Limestone Collection Account only pursuant to and in accordance with
this Agreement.

                  (d) If on any Limestone Distribution Date the Trustee
ascertains that the Available Funds in the Limestone Distribution Account or the
Limestone Collection Account, as applicable, are then insufficient to pay in
full the amount required to be paid from the Limestone Distribution Account or
the Limestone Collection Account, as applicable, then, if any investments are
held in the Limestone Distribution Account and/or the Limestone Collection
Account, as applicable, the Trustee shall sell or otherwise liquidate all or
such portion of such investments as is necessary to pay in full the required
amount. If at any time the Trustee is required to certify as to the Available
Funds in the Limestone Distribution Account and the Limestone Collection Account
in connection with the calculation of the Share Trust Amount (including any
certification pursuant to Section 6.07(c)), then the Trustee shall liquidate the
investments, if any, then held in the Limestone Distribution Account or
Limestone Collection Account up to an amount that, in the aggregate with all
other funds then held in the Limestone Distribution Account and Limestone
Collection Account, shall cause the Share Trust Amount to equal zero.

                  Section 6.03. Distributions from the Limestone Distribution
Account. The Trustee shall direct the Securities Intermediary to withdraw and
distribute all Available Funds held in the Limestone Distribution Account
pursuant to and in accordance with this Section 6.03.

                  (a) To the extent funds are received by the Trust on or prior
to 12:00 noon (New York City time) on any Limestone Distribution Date, then, on
or before 2:00 p.m. New York City time on such date, the Trustee, on behalf of
and for the benefit of the Trust, shall distribute or cause to be distributed
all Available Funds (other than funds received as a result of a distribution or
payment described in Section 6.03(b) and without duplication of payments made
under Section 6.04) then on deposit in the Limestone Distribution Account in the
following order of priority, with the amount of each such distribution (and the
components thereof) being determined by the Trustee and set forth in the related
Limestone Distribution Date Statement:

                           (i) first, pro rata to the Certificateholders, the
         accrued and unpaid Limestone Certificate Yield then due and payable in
         respect of the Limestone Certificates held by such Certificateholders
         and accrued and unpaid Default Yield with respect to any overdue
         payment of Limestone Certificate Yield, if any;

                           (ii) second, pro rata to the Certificateholders, all
         amounts the Trust is entitled to receive in respect of the Class A
         Member Interest or, when the EP Purchase Option Deposit Amount has been
         paid under Section 7.02, an amount equal to the EP Purchase Option
         Deposit Amount (in each case less any amounts distributed in accordance
         with priority first above);

                           (iii) third, until the cancellation or deemed
         cancellation of all Limestone Certificates pursuant to Section 7.04,
         any amounts remaining in the Limestone

                                       21
<PAGE>

         Distribution Account to be invested in Financial Investments; provided
         that if an El Paso Debt Obligation Repayment Event has occurred, such
         amounts shall be invested in Financial Investments other than El Paso
         Debt Obligations and commercial paper issued by El Paso; and

                           (iv) fourth, following the cancellation or deemed
         cancellation of all Limestone Certificates pursuant to Section 7.04, to
         the holder of the El Paso Interest, any remainder.

                  (b) (i) If Chaparral makes a Special Class A Tax
Distribution pursuant to Section 5.1(c) of the Chaparral LLC Agreement, (ii) El
Paso makes any payments pursuant to the Tax Indemnification Agreement, (iii) the
Trust receives any payment in respect of the Share Trust Amount from any of the
Indenture Trustee, the Share Trust, the Remarketing Agents or El Paso, or (iv)
the Trust receives any payment from the holder of the El Paso Interest pursuant
to Section 3.03(b), in each case, to the extent funds are received by the Trust
on or prior to 12:00 noon New York City time on any such date, on or before 2:00
p.m. New York City time on such date, the Trustee, on behalf of and for the
benefit of the Trust, shall distribute or cause to be distributed all Available
Funds then on deposit in the Limestone Distribution Account to the
Certificateholders (in the case of amounts described in clauses (iii) or (iv),
on a pro rata basis and first to the payment of yield as described in Section
6.03(a)(i)), with the amount of each such distribution (and the components
thereof) being determined by the Trustee and set forth in the related Limestone
Distribution Date Statement.

                  (c) Each Certificateholder shall be deemed to agree, by its
acceptance of a Limestone Certificate, that it shall promptly remit to the
Trustee for payment in accordance with this Section 6.03 any excess payment it
has received.

                  (d) All payments made to the Certificateholders on any
Limestone Distribution Date shall be made to the Certificateholders of record as
of the close of business on the last Business Day of the calendar month
immediately preceding such Limestone Distribution Date (the "Certificate Record
Date").

                  (e) The Certificateholders shall be entitled to receive
distributions hereunder on any Limestone Distribution Date or on such other date
as provided for in Section 6.03(b), by wire transfer to the account specified in
writing by the applicable Certificateholder to the Trustee. In each case, the
account must be specified in writing no later than the Certificate Record Date
for the Limestone Distribution Date on which wire transfers will commence.

                  Section 6.04. Distributions from the Limestone Collection
Account. The Trustee shall direct the Securities Intermediary to withdraw and
distribute all Available Funds on deposit from time to time in the Limestone
Collection Account pursuant to and in accordance with this Section 6.04.

                  (a) To the extent funds are received by the Trust on or prior
to 12:00 noon New York City time, on any Limestone Distribution Date prior to
the date upon which the Limestone Notes are repaid in full, then, on or before
2:00 p.m. New York City time on such date, the Trustee, on behalf of and for the
benefit of the Trust, shall distribute or cause to be

                                       22
<PAGE>

distributed all Available Funds then on deposit in the Limestone Collection
Account to the Indenture Trustee for deposit into the Indenture Collection
Account.

                  (b) Following the repayment in full of the Outstanding
Limestone Notes, but prior to the repayment in full of the New Limestone Notes,
to the extent funds are received by the Trust on or prior to 12:00 noon New York
City time, on any Limestone Distribution Date, then, on or before 2:00 p.m. New
York City time on such date, the Trustee, on behalf of and for the benefit of
the Trust, shall distribute or cause to be distributed all Available Funds then
on deposit in the Limestone Collection Account to the New Indenture Trustee for
deposit into the New Notes Account.

                  (c) Following the repayment in full of the Outstanding
Limestone Notes and the New Limestone Notes, to the extent funds are received by
the Trust on or prior to 12:00 noon New York City time on any Limestone
Distribution Date, then, on or before 2:00 p.m. New York City time on such date,
the Trustee, on behalf of and for the benefit of the Trust, shall distribute all
Available Funds then on deposit in the Limestone Collection Account in the
following order of priority, with the amount of each such distribution (and the
components thereof) being determined by the Trustee and set forth in the related
Limestone Distribution Date Statement:

                  (i) first, pro rata to the Certificateholders, the accrued and
unpaid Limestone Certificate Yield then due and payable in respect of the
Limestone Certificates held by such Certificateholders and accrued and unpaid
Default Yield, if any;

                  (ii) second, pro rata to the Certificateholders, all amounts
the Trust is entitled to receive in respect of the Class A Member Interest (less
any amounts distributed in accordance with priority first above);

                  (iii) third, to the Trustee for the payment of Administrative
Expenses;

                  (iv) fourth, until the cancellation or deemed cancellation of
all Limestone Certificates pursuant to Section 7.04, any amounts remaining in
the Limestone Collection Account to be invested in Financial Investments;
provided that if an El Paso Debt Obligation Repayment Event has occurred, such
amounts shall be invested in Financial Investments other than El Paso Debt
Obligations and commercial paper issued by El Paso; and

                  (v) fifth, following the cancellation or deemed cancellation
of all Limestone Certificates pursuant to Section 7.04, to the holder of the El
Paso Interest, any remainder.

                  Section 6.05. Limestone Distribution Date Statements. On each
Limestone Distribution Date, the Trustee shall prepare and deliver to the
Certificateholders and the holder of the El Paso Interest a statement (the
"Limestone Distribution Date Statement") setting forth for the period since the
preceding Limestone Distribution Date, as applicable (i) the amount, nature and
origin of all income, proceeds, payments and collections received in the
Limestone Distribution Account or the Limestone Collection Account, as
applicable, and (ii) the amounts to be paid or distributed pursuant to Section
6.03(a) or (b) or Section 6.04(a), (b) or (c).

                  Section 6.06. Withholding. Notwithstanding any other provision
of this Agreement to the contrary, each Certificateholder hereby authorizes the
Trustee to withhold and

                                       23
<PAGE>

to pay over any taxes (including any interest or penalties related thereto)
payable by the Trust as a result of such Certificateholder's participation in
the Trust. The Trustee will give each such Certificateholder at least five (5)
days notice prior to any such withholding. If and to the extent that the Trust
shall be required to withhold any such taxes (including any interest or
penalties related thereto), such Certificateholder shall, in the sole discretion
of the Trustee, (i) pay the amount of such withholding to the Trust within five
(5) days of being notified in writing of the amount to be withheld by the Trust
or (ii) be deemed for all purposes of this Agreement to have received a payment
from the Trust as of the time such withholding is required to be paid, which
payment shall be deemed to be a distribution to the extent that the
Certificateholder is then entitled to receive a distribution. To the extent that
the aggregate of such payments to a Certificateholder for any fiscal period
exceeds the distributions to which such Certificateholder is entitled for such
period, the amount of such excess shall be considered a loan from the Trust to
such Certificateholder, with interest at 10.35% per annum (which interest shall
be treated as an item of Trust income), until discharged by such
Certificateholder by repayment directly or out of distributions to which such
Certificateholder would otherwise subsequently be entitled. The withholdings
referred to in this Section 6.06 shall be made at the maximum applicable
statutory rate under the applicable tax law unless the Trustee shall have
received an opinion of counsel or other evidence, satisfactory to the Trustee,
to the effect that a lower rate is applicable, or that no withholding is
applicable.

                  Section 6.07. Information Provided by the Trustee. (a) The
Trustee shall provide to the Indenture Trustee and the New Indenture Trustee, if
applicable, promptly upon receipt any information which the Trust receives from
Chaparral in connection with any distribution in accordance with the Chaparral
LLC Agreement, including notice with respect to the use of any such distribution
to cause an Optional Redemption or Mandatory Redemption of the Limestone Notes
or the New Limestone Notes, or both.

                  (b) The Trustee shall provide to the Managing Member, promptly
upon receipt of written notice from Electron, written notice of any reduction in
the amount of the Limestone Equity Cash Component or Limestone Equity PIK
Component.

                  (c) The Trustee shall, upon the written request of the
Remarketing Agents or El Paso, promptly (but in any event within five Business
Days of such request) deliver to the Remarketing Agents, the Indenture Trustee
and El Paso an Officer's Certificate setting forth the amount of Available Funds
then on deposit in the Limestone Collection Account and the Limestone
Distribution Account (after giving effect to any liquidation of investments that
is required to be made pursuant to the last sentence of Section 6.02(d)), which
certification shall be used in connection with the calculation of the Share
Trust Amount, and hereby undertakes to notify the Remarketing Agents, the
Indenture Trustee and El Paso if any such amount should change prior to the Rate
Reset Date.

                  (d) The Trustee shall provide to the holder of the El Paso
Interest and the Share Trustee written notice of (i) the receipt by the
Certificateholders of proceeds of Collections received by the Trustee from the
Share Trust in an aggregate amount equal to the amount of the aggregate proceeds
received by the Noteholders from the Asset Remedy, any Asset Disposition or
asset sales (in connection with an enforcement proceeding following a judgment
against the Issuers) (in each case, as such amounts are certified by the
Indenture Trustee), (ii) the occurrence

                                       24
<PAGE>

of the Final Payment Date, if such date occurs after the satisfaction and
discharge of the Indenture, and (iii) the date on which the Share Trust Amount
equals zero, if such date occurs after the satisfaction and discharge of the
Indenture, in each case, promptly upon such receipt by the Certificateholders or
such occurrence, as the case may be (but in any event within five Business Days
after such receipt or occurrence).

                  (e) Upon the distribution to the Indenture Trustee of any
contributions received by the Trust pursuant to Sections 3.02(d) and 3.03(a)
which the Trustee has been notified are to be used to cause an Optional
Redemption of the Limestone Notes, the Trustee shall provide notice to the
Indenture Trustee that such amounts distributed to the Indenture Trustee are to
be used to cause an Optional Redemption of the Limestone Notes.

                  (f) Upon the repayment in full of the New Limestone Notes, if
any proceeds from the Asset Remedy, an Asset Disposition or asset sales (in
connection with an enforcement proceeding following a judgment against the
Issuers) were used to repay the New Limestone Notes, the Trustee shall provide
to the holder of the El Paso Interest a notice requesting payment pursuant to
Section 3.03(b), which notice shall include, to the extent applicable, (i) the
amount of proceeds from the Asset Remedy, Asset Disposition or asset sales (in
connection with an enforcement proceeding following a judgment against the
Issuers) received by the Trustee from Chaparral pursuant to the Chaparral LLC
Agreement, (ii) the amount of such proceeds distributed to the New Indenture
Trustee pursuant to Section 6.04(b) and (iii) any amounts received from the New
Indenture Trustee and deposited into the Limestone Distribution Account after
the repayment in full of the New Limestone Notes.

                  (g) Upon the occurrence of a Specified Equity Event and the
Trustee's receipt of written notice thereof from any Certificateholder, the
Trustee shall deliver a written notice (an "Equity Event Notice") to El Paso,
the Indenture Trustee (so long as any Limestone Notes are outstanding) and the
New Indenture Trustee (so long as any New Limestone Notes are outstanding),
which shall specifically state that it is an Equity Event Notice and that upon
the Trustee's receipt of proceeds from an Asset Disposition or, after the
satisfaction and discharge of the Indenture, proceeds from the exercise of the
Asset Remedy in connection with such Specified Equity Event, the Limestone Notes
and the New Limestone Notes will be subject to a Special Redemption in
accordance with Article XV of the Indenture and Article XV of the New Indenture,
as applicable.

                  Section 6.08. Limitations on Distributions to the
Certificateholders. For the avoidance of doubt, in no event shall the
Certificateholders receive distributions from the Trust in an amount exceeding
the Certificate Purchase Amount at any time; provided that, for purposes of this
Section 6.08, such distributions shall be deemed to exclude any indemnity or
expense reimbursement payments to which any Indemnified Persons are entitled
pursuant to any of the Transaction Documents.

                                       25
<PAGE>

                                   ARTICLE VII

         LIMESTONE CERTIFICATE TRIGGER EVENTS; SPECIFIED EQUITY EVENTS;
       LIMESTONE CERTIFICATE PURCHASE RIGHT; CERTIFICATE PURCHASE OPTION;
                                EARN-OUT PERIOD;
                     CANCELLATION OF LIMESTONE CERTIFICATES

                  Section 7.01. Consequences of a Limestone Certificate Trigger
Event or Specified Equity Event. (a) Until the Limestone Notes have been repaid
in full, upon the occurrence of a Limestone Certificate Trigger Event, the
Required Certificateholders shall have the right to direct the Indenture Trustee
to commence the Asset Remedy. Such Asset Remedy shall be exercised in accordance
with (i) Section 9.04(g) of the Indenture and (ii) Section 11.3 of the Chaparral
LLC Agreement, and any proceeds therefrom received by the Trust, as Class A
Member of Chaparral, shall be deposited into the Limestone Collection Account
and applied in accordance with Section 6.04 of this Agreement.

                  (b) After the Limestone Notes have been repaid in full, upon
the occurrence of a Specified Equity Event, the Required Certificateholders
shall have the right to direct the Trustee to commence the Asset Remedy;
provided that the Trustee may pursue the Asset Remedy only if (i) the Required
Certificateholders shall have directed the Trustee to commence the Asset Remedy
and delivered a copy of such direction to El Paso, (ii) the Special Management
Standstill Expiration Date shall have occurred without the Specified Equity Cure
occurring on or before the 30th day after the relevant Specified Equity Event
and (iii) the holder of the El Paso Interest has not consummated the Certificate
Purchase Option pursuant to Section 7.02(b). Such Asset Remedy shall be
exercised in accordance with Section 11.3 of the Chaparral LLC Agreement, and
any proceeds therefrom received by the Trust, as Class A Member of Chaparral,
shall be deposited into the Limestone Collection Account and applied in
accordance with Section 6.04(b) or Section 6.04(c), as applicable, of this
Agreement.

                  (c) Upon the occurrence of a Specified Equity Event, the
Required Certificateholders shall have the right to direct the Trustee to
exercise the rights of Limestone under Section 6.1(a) of the Chaparral LLC
Agreement in connection with such Specified Equity Event; provided that the
Trustee may exercise the rights of Limestone under Section 6.1(a) of the
Chaparral LLC Agreement only if (i) the Required Certificateholders shall have
directed the Trustee to exercise the rights of Limestone under Section 6.1(a) of
the Chaparral LLC Agreement in connection with such Specified Equity Event and
delivered a copy of such direction to El Paso, (ii) the Special Management
Standstill Expiration Date shall have occurred without the Specified Equity Cure
occurring on or before the 30th day after the relevant Specified Equity Event
and (iii) the holder of the El Paso Interest has not consummated the Certificate
Purchase Option pursuant to Section 7.02(b). If, as a result of or following
such exercise, an Asset Disposition has been consummated, any proceeds therefrom
received by the Trust, as Class A Member of Chaparral, shall be deposited into
the Limestone Collection Account and applied in accordance with Section 6.04(b)
or Section 6.04(c), as applicable, of this Agreement.

                  Section 7.02. Limestone Certificate Purchase Right;
Certificate Purchase Option. (a) The holder of the El Paso Interest or its
designees or assigns shall have the right (the "Limestone Certificate Purchase
Right"), concurrently with the repayment, at maturity or

                                       26
<PAGE>

otherwise, of the principal of the Limestone Notes and the New Limestone Notes
(in each case, to the extent then Outstanding), to purchase or cause a third
party to purchase the outstanding Limestone Certificates at a purchase price
(the "EP Purchase Option Deposit Amount") equal to the Certificate Purchase
Amount. The holder of the El Paso Interest or its designees or assigns shall
exercise such right by providing written notice of such exercise to the
Certificateholders and the Trustee within 10 days of the event giving rise to
the Limestone Certificate Purchase Right, which notice shall be irrevocable, and
by depositing or causing the deposit of the EP Purchase Option Deposit Amount
within 90 days of such notice in the Limestone Distribution Account to be
distributed to the Certificateholders in accordance with Section 6.03(a).

                  (b) The holder of the El Paso Interest or its designees
or assigns shall have the option at any time (the "Certificate Purchase Option")
to purchase or cause a third party to purchase the outstanding Limestone
Certificates at a price equal to the EP Purchase Option Deposit Amount. The
holder of the El Paso Interest or its designees or assigns shall exercise such
right by (i) providing written notice of such exercise to the Certificateholders
and the Trustee, which notice shall be irrevocable, no later than the earliest
to occur of (A) if a Specified Equity Event has occurred, the earlier of the
Special Management Replacement Date and the date on which Limestone, as Class A
Member, shall have delivered an Asset Remedy Notice pursuant to Section 11.3 of
the Chaparral LLC Agreement and such Asset Remedy Notice shall have become
effective pursuant to Section 11.3(a)(i) of the Chaparral LLC Agreement and (B)
the date on which Limestone, as Class A Member, shall have delivered a
Liquidation Notice pursuant to Section 12.10 of the Chaparral LLC Agreement and
such Liquidation Notice shall have become effective pursuant to Section 12.10(a)
of the Chaparral LLC Agreement and (ii) depositing or causing the deposit of the
EP Purchase Option Deposit Amount in the Limestone Distribution Account on or
prior to 12:00 noon New York City time on the date that is not more than five
Business Days after the earliest to occur of the dates referred to in clauses
(A) and (B) herein, to be distributed to the Certificateholders in accordance
with Section 6.03(a).

                  Section 7.03. Earn-Out Period. If the holder of the El Paso
Interest or its designee or assign has not (i) deposited the EP Purchase Option
Deposit Amount on or prior to the 90th day following notice of its exercise of
the Limestone Certificate Purchase Right in accordance with Section 7.02(a),
(ii) given notice of its exercise of the Limestone Certificate Purchase Right
within 10 days after the occurrence of the Earn-Out Period Commencement Date or
(iii) prior to the Earn-Out Period Commencement Date but after the satisfaction
and discharge of the Indenture and the New Indenture, and after the occurrence
of a Specified Equity Event, deposited the EP Purchase Option Deposit Amount on
or prior to the Special Management Standstill Expiration Date for such Specified
Equity Event, the Required Certificateholders shall have the right to direct the
Trustee to exercise the rights of the Trust as holder of the Class A Member
Interest, including, to cause an Asset Remedy Notice to be delivered to
Chaparral from time to time in accordance with Section 11.3(b) of the Chaparral
LLC Agreement and to cause the liquidation and sale of the assets of Chaparral
pursuant to Section 12.10(b) of the Chaparral LLC Agreement. Any proceeds from
the sale of the assets of Chaparral paid to the Trust as holder of the Class A
Member Interest and any distributions from Chaparral in respect of the Class A
Member Interest during the Earn-Out Period shall be deposited in the Limestone
Collection Account and applied in accordance with Section 6.04(b) or Section
6.04(c), as applicable.

                                       27
<PAGE>

                  Section 7.04. Cancellation of Limestone Certificates. (a)
Subject to Section 7.04(b) below, after the repayment in full of the Outstanding
Limestone Notes and the New Limestone Notes, upon the receipt by any
Certificateholder of such Certificateholder's Proportionate Interest of the
Certificate Purchase Amount, either as a result of distributions pursuant to
this Agreement or payments to which such Certificateholder is entitled pursuant
to any other Transaction Document, in each case attributable to the Limestone
Certificate(s) held by such Certificateholder, (i) such Limestone Certificate(s)
shall be deemed to be no longer outstanding for purposes of this Agreement, (ii)
such Certificateholder's right to receive distributions under Article VI shall
immediately terminate and (iii) such Certificateholder shall, within five
Business Days after request by the holder of the El Paso Interest, deliver its
original Limestone Certificate(s) to the Trustee, and such Limestone
Certificate(s) shall be immediately cancelled by the Trustee; provided that, for
all purposes of this Agreement, such Limestone Certificate(s) shall be deemed to
have been cancelled on the date on which the applicable Certificateholder
received its Proportionate Interest of the Certificate Purchase Amount; provided
further that such cancellation or deemed cancellation shall not affect such
Certificateholder's rights to indemnity or reimbursement. Upon cancellation (or
deemed cancellation) of any Limestone Certificate pursuant to this Section 7.04,
the Trustee shall promptly (but in any event, within five Business Days after
request therefor by the holder of the El Paso Interest) deliver a certificate of
the Trustee to each of the Indenture Trustee, the Share Trustee, the Overfund
Trustee, the Management Company and the holder of the El Paso Interest,
certifying (x) as to the aggregate Certificate Face Amount of the Limestone
Certificate(s) so cancelled and (y) as to the aggregate Certificate Face Amount
of all outstanding Limestone Certificates (after giving effect to such
cancellation) (or, if all outstanding Limestone Certificates shall have been
cancelled or deemed cancelled, certifying as to such cancellation).

                  (b) Notwithstanding Section 7.04(a) above, a
Certificateholder's Limestone Certificates shall not be cancelled upon receipt
by such Certificateholder of its Proportionate Interest of the Certificate
Purchase Amount if such receipt was as a result of the exercise of the Limestone
Certificate Purchase Right or the Certificate Purchase Option; provided that if
El Paso or any Affiliate of El Paso acquires any Limestone Certificates through
the exercise of the Limestone Certificate Purchase Right or the Certificate
Purchase Option, such Person shall have the option to deliver its Limestone
Certificates to the Trustee for cancellation.

                                  ARTICLE VIII

                     RIGHTS, OBLIGATIONS, POWERS AND STATUS
                            OF THE CERTIFICATEHOLDERS
                     AND THE HOLDER OF THE EL PASO INTEREST

                  Section 8.01. Management of the Trust. It is the intention of
the parties hereto and the Certificateholders by their acceptance thereof shall
be deemed to agree, that the Trustee's duties are to be ministerial in nature
only. Subject to Article VII, Sections 8.05 and 10.01(a) hereof, the
Certificateholders (or the portion thereof as provided herein) shall have the
exclusive right and obligation to determine the matters herein referenced to be
determined by the Certificateholders and to direct the Trustee to carry out and
accomplish such matters, and the Certificateholders, in that capacity, subject
to the provisions of the Act, the other provisions of

                                       28
<PAGE>

this Agreement and the Transaction Documents, shall direct the management of the
business and affairs of the Trust, in a manner consistent with the provisions of
this Agreement and the Act in order best to carry out the Trust's purposes.

                  Section 8.02. Bankruptcy, Dissolution or Termination of any
Certificateholder. The incapacity, dissolution, termination or bankruptcy of any
Certificateholder shall not result in the termination or dissolution of the
Trust.

                  Section 8.03. Creditors of the Certificateholders. As is
provided in paragraph (b) of Section 3805 of the Act, no creditor of a
Certificateholder shall have any right to obtain possession of, or otherwise
exercise legal or equitable remedies with respect to, the Trust Estate.

                  Section 8.04. Certain Rights of the Majority
Certificateholders. Subject to Section 8.05, the Majority Certificateholders
shall have the right to direct the following matters on behalf of all
Certificateholders:

                  (a) directing the Trustee in accordance with Sections 8.01 and
9.01(d) (including directing the Trustee to exercise the rights of the
beneficial owner of the Class A Member Interest under Section 7.4 of the
Chaparral LLC Agreement);

                  (b) instructing the Trustee to amend the Certificate of Trust
or this Agreement in accordance with Sections 9.03(a) or 12.04;

                  (c) appointing a replacement Trustee pursuant to Section 9.05;
and

                  (d) instructing the Trustee to appear in, prosecute or defend
any action in accordance with Section 9.09(a).

                  Section 8.05. Voting and Other Rights of the Holder of the El
Paso Interest. (a) Notwithstanding anything in this Agreement to the contrary,
the following actions by the Trust will require the prior written consent of the
holder of the El Paso Interest:

                  (i) the dissolution, liquidation, consolidation or merger of
the Trust (with or into any other person) or the sale of all or substantially
all of the Trust Estate;

                  (ii) the taking of any Bankruptcy Action with respect to the
Trust;

                  (iii) the amendment of any Transaction Document to which the
Trust is a party (including any amendment to this Agreement or the Certificate
of Trust);

                  (iv) the repudiation by the Trust of any of the Transaction
Documents (other than any action provided for in Section 7.03, to the extent
such action constitutes a repudiation); and

                  (v) the replacement of the Trustee pursuant to Section 9.05.

                  (b) The holder of the El Paso Interest will have no other
voting rights until the earlier to occur of (i) the purchase of all of the
outstanding Limestone Certificates pursuant to

                                       29
<PAGE>

Section 7.02 or (ii) the cancellation of all of the Limestone Certificates
pursuant to Section 7.04. Upon any such purchase or cancellation of all
outstanding Limestone Certificates, the holder of the El Paso Interest shall
have the exclusive right to exercise all voting rights hereunder and to deliver
all instructions to the Trustee in connection with this Agreement.

                  (c) Until the occurrence of an El Paso Debt Obligation
Repayment Event, the holder of the El Paso Interest shall have the right to
direct, by written notice to the Trustee signed by a Responsible Officer of El
Paso, the investment of the Available Funds in the Limestone Distribution
Account and the Limestone Collection Account, in Financial Investments.

                  (d) The holder of the El Paso Interest shall have the
exclusive right to direct, by written notice to the Trustee signed by an
Authorized Officer of El Paso, the amendment of Sections 7.01(cc), (dd), (ee),
(ff) and (gg) of the New Indenture (provided that such amendments are not
inconsistent with and do not attempt to override any other provision of any
Transaction Document), and the Certificateholders shall have no right to direct
any such amendment or consent to any such amendment.

                                   ARTICLE IX

CONCERNING THE TRUSTEE, THE SECURITIES INTERMEDIARY AND WILMINGTON TRUST COMPANY

                  Section 9.01. General. (a) In the exercise or administration
of the Trust hereunder (and, without limitation, with respect to taking any
action pursuant to the terms of paragraph (a) of Section 10.01), the Trustee at
the expense of the Trust (to be paid as provided in Section 9.08) may (i) act
directly or through agents or attorneys pursuant to agreements entered into with
any of them, and the Trustee shall not be liable for the default or misconduct
of such agents or attorneys if such agents or attorneys shall have been selected
by the Trustee with reasonable care, and (ii) consult with counsel, accountants
and other skilled Persons to be selected with reasonable care and employed by
the Trustee, and it shall not be liable for anything done, suffered or omitted
in good faith by it in accordance with the advice or opinion of any such
counsel, accountants or other skilled Persons.

                  (b) Except as expressly provided herein, (i) in accepting the
Trust hereby continued, Wilmington Trust Company acts solely as Trustee
hereunder and not in its individual capacity, and (ii) all Persons having any
claim against the Trust or the Trustee by reason of the transactions
contemplated by this Agreement shall look only to the Trust's property for
payment or satisfaction thereof.

                  (c) Except in accordance with the written instructions
furnished by the Required Certificateholders or except as provided herein, the
Trustee shall have no duty to (i) see to any recording or filing of any
document, or (ii) see to the payment or discharge of any tax, assessment or
other governmental charge or any lien or encumbrance of any kind owing with
respect to, assessed or levied against any part of the Trust.

                                       30
<PAGE>

                  (d) The Trustee will administer the business and affairs of
the Trust in accordance with the terms of the Act and the Transaction Documents
to which the Trust is a party; provided, however, that the Trustee undertakes to
perform only such duties as are specifically set forth in this Agreement and as
the Trustee may be duly directed from time to time in writing by the Majority
Certificateholders in accordance with and subject to the Transaction Documents
to which the Trust is a party and as the Trustee is required to in order to
comply with the Transaction Documents to which the Trust is a party. The Trustee
shall not have any duty or obligation to manage, control, use, sell, dispose of
or otherwise deal with the Trust or to otherwise take or refrain from taking any
action under this Agreement or the other Transaction Documents to which the
Trust is a party except as expressly required by the terms hereof (or of the
Transaction Documents to which the Trust is a party) or as expressly provided in
written instructions from the Majority Certificateholders, and no implied duties
or obligations shall be read into this Agreement against the Trustee. Wilmington
Trust Company nevertheless agrees that it will, at its own cost and expense (and
not at the expense of the Trust), promptly take all action as may be necessary
to discharge any Liens on any part of the Trust Estate which are attributable to
actions by or claims against Wilmington Trust Company that are not related to
the ownership of any part of the Trust Estate or the administration of the Trust
Estate or the transactions contemplated by this Agreement.

                  (e) The Trustee shall not be required to take any action under
this Agreement if the Trustee shall reasonably determine or shall have been
advised by counsel that such action is contrary to the terms of this Agreement
or is otherwise contrary to Applicable Law.

                  (f) Subject to paragraph (a) of Section 10.01, whenever the
Trustee is unable to decide between alternative courses of action permitted or
required by the terms of this Agreement, or is unsure as to the application,
intent, interpretation or meaning of any provision hereof, the Trustee may give
notice (in such form as shall be appropriate under the circumstances) to the
Certificateholders and, in any circumstance contemplated in Section 8.05, the
holder of the El Paso Interest, requesting written instructions as to the course
of action to be adopted, and, to the extent the Trustee acts in good faith in
accordance with any such appropriate instruction received from the Required
Certificateholders, the Trustee shall not be liable on account of such action or
inaction to any Person. If the Trustee shall not have received appropriate
instructions within ten days of such notice (or within such shorter period of
time as reasonably may be specified in such notice or may be necessary under the
circumstances), it may, but shall be under no duty to, take or refrain from
taking such action which is consistent, in its view, with this Agreement and as
it shall deem to be in the best interests of the Certificateholders and, in any
circumstance contemplated in Section 8.05, the holder of the El Paso Interest,
and the Trustee shall have no liability to any Person for any such action or
inaction.

                  (g) In no event whatsoever shall the Trustee be liable for any
representation, warranty, covenant, agreement, indebtedness or other obligation
of the Trust; provided, however, the foregoing shall, in no event whatsoever,
relieve the Trustee from any liability resulting from the Trustee's bad faith,
willful misconduct or gross negligence.

                  (h) The Trustee may rely upon and shall incur no liability to
anyone in acting upon any signature, instrument, notice, resolution, request,
consent, order, certificate, report,

                                       31
<PAGE>

opinion, bond or other document or paper reasonably believed by it to be genuine
and reasonably believed by it to be signed by the proper party or parties. The
Trustee may accept a certified copy of a resolution of the board of directors or
other governing body of any corporate party as conclusive evidence that such
resolution has been duly adopted by such body and that the same is in full force
and effect. As to any fact or matter the manner of ascertainment of which is not
specifically prescribed herein, the Trustee may for all purposes hereof rely on
a certificate, signed by the president or any vice president or by the treasurer
or any assistant treasurer or the secretary or any assistant secretary (or
equivalent position) of the relevant party, as to such fact or matter, and such
certificate shall constitute full protection to the Trustee for any action taken
or omitted to be taken by it in good faith reliance thereon.

                  (i) The Trustee shall not be personally liable for any error
of judgment made in good faith by a Responsible Officer of the Trustee.

                  (j) The Trustee shall not be required to take any action that
is inconsistent with the purposes of the Trust set forth in Section 1.04.

                  (k) No provision of this Agreement shall require the Trustee
to expend or risk its personal funds, or otherwise incur any financial liability
in the performance of its rights or powers hereunder, if the Trustee shall have
reasonable grounds for believing that repayment of such funds or adequate
indemnity against such risk or liability is not reasonably assured or provided
to it.

                  (l) The Trustee may fully rely upon and shall have no
liability in connection with calculations or instructions forwarded to the
Trustee by the Certificateholders, unless the Trustee determines that such
calculations or instructions are in error; provided, however, the Trustee shall
have no obligation to make any such determination.

                  (m) The Trustee shall not have any responsibility or liability
for or with respect to the genuineness, value, sufficiency or validity of the
Trust Estate. The Trustee shall in no event assume or incur any liability, duty
or obligation to the Depositor, the Certificateholders or any other Person other
than as expressly provided for herein, and in no event shall the Trustee have
any implied duties or obligations hereunder.

                  (n) The Trustee shall incur no liability if, by reason of any
provision of any future law or regulation thereunder, the Trustee shall be
prevented or forbidden from doing or performing any act or thing which the terms
of this Agreement provide shall or may be done or performed.

                  Section 9.02. Acceptance of the Trust. Wilmington Trust
Company declares that it accepts the Trust hereby continued and agrees to
perform its duties under this Agreement and the Act but only upon the terms of
this Agreement as contemplated by the Transaction Documents.

                  Section 9.03. Authority and Duties of the Trustee. (a) The
Trustee is authorized and directed to execute and deliver this Agreement, the
Participation Agreement, the Chaparral LLC Agreement, the Indenture, the
Security Agreement, the Remarketing Agreement, the Closing Agreement, the Dealer
Manager Agreement, the New Indenture, any other Transaction

                                       32
<PAGE>

Document to which the Trust or the Trustee is a party, and each certificate or
other document attached as an exhibit to or contemplated by any such agreement,
which agreements, or amendments thereto, as applicable (other than the
Commencement Date Documents), may be declared effective by the Trustee upon
receipt of notice from the Certificateholders that all conditions precedent set
forth in Section 5 of the Closing Agreement have been satisfied. The execution
and delivery of, and performance of the terms of, the Participation Agreement,
the Chaparral LLC Agreement, the Indenture, the Security Agreement, the
Remarketing Agreement, the Closing Agreement, the Dealer Manager Agreement, the
New Indenture and each certificate of other document attached as an exhibit to
or otherwise expressly contemplated by any such agreement shall be deemed not to
conflict with or constitute a breach or default under this Agreement. The
Trustee shall have only such authority and duties as are expressly set forth in
this Agreement. Subject to Sections 10.02 and 12.04, the Trustee shall, upon the
written instruction of the Majority Certificateholders (and the holder of the El
Paso Interest with respect to clause (i) below), (i) amend the Certificate of
Trust or this Agreement and (ii) execute, acknowledge, deliver, file or record
any document or instrument necessary or appropriate to carry out the provisions
of this Agreement, the Participation Agreement, the Chaparral LLC Agreement, the
Indenture, the Security Agreement, the Remarketing Agreement, the Closing
Agreement, the Dealer Manager Agreement or the New Indenture in such form as is
provided to it; provided that such action does not alter the rights, powers and
duties of the Trustee as set forth in this Article IX.

                  (b) The Trustee shall have the power and authority to execute,
deliver, acknowledge and file all necessary documents and to maintain all
necessary records of the Trust as required by the Act.

                  (c) In the performance of its duties under this Agreement, the
Trustee may rely on any document believed by it to be genuine and to have been
signed or presented by the proper Person. The Trustee need not investigate any
fact or matter stated in any such document, but the Trustee, in its discretion,
may make further inquiry or investigation.

                  (d) The Trustee shall cause to be prepared and filed, such tax
returns and Periodic Filings relating to the Trust, and make such elections as
may from time to time be required or appropriate under any applicable Federal,
state or local tax statute or rule or regulation thereunder so as to maintain to
the extent possible the Trust's characterization set forth in Section 12.07.

                  (e) Subject to the provisions of any applicable
confidentiality agreement to which the Trust is or becomes a party, the Trustee
shall furnish to the Certificateholders and the holder of the El Paso Interest,
promptly upon receipt thereof, duplicates or copies of all reports, notices,
requests, demands, certificates, financial statements and any other instruments
furnished to the Trustee hereunder, under the Participation Agreement (other
than the information the Trustee is deemed to have received under Section
5.1(e)(i), (ii), (iii), or (iv) of the Participation Agreement), or under any
other Transaction Document to which the Trust is a party, provided that the
Trustee shall not be required to furnish the Certificateholders with a copy of
any such materials if the Trustee determines that such party has otherwise
received such copies, unless such Certificateholder so requests.

                                       33
<PAGE>

                  Section 9.04. Representations and Warranties of Wilmington
Trust Company. Wilmington Trust Company, in its individual capacity, hereby
represents and warrants to the holder of the El Paso Interest and the
Certificateholders from time to time that, as of the date hereof and as of the
Effective Date:

                  (a) it is duly incorporated, validly existing and in good
         standing under the laws of its jurisdiction of incorporation;

                  (b) it is has the corporate power and authority to execute,
         deliver and perform its obligations under this Agreement, and this
         Agreement has been duly authorized by it by all necessary corporate
         action;

                  (c) no authorization, consent or approval of any governmental
         authority, regulatory body or other Person is required for the due
         authorization, execution, delivery or performance by it of this
         Agreement (other than the filing of the Certificate of Trust);

                  (d) this Agreement has been duly executed and delivered by it
         and (subject to the due execution and delivery hereof by the holder of
         the El Paso Interest and the Certificateholders) constitutes a legal
         and binding obligation of it, enforceable against it in accordance with
         its terms, except as enforceability may be limited by applicable
         bankruptcy, insolvency, reorganization, moratorium or other similar
         laws now or hereinafter in effect, relating to the enforcement of
         creditors' rights in general and except as such enforceability may be
         limited by general principles of equity (whether considered in a
         proceeding at law or in equity); and

                  (e) it complies with all the requirements of the Act relating
         to the qualification of a trustee of a Delaware business trust.

                  Section 9.05. Resignation of the Trustee. (a) The Trustee may
resign by giving 60 days' prior written notice to the Certificateholders and the
holder of the El Paso Interest. In the case of the resignation of the Trustee,
the Majority Certificateholders shall, with the consent of the holder of the El
Paso Interest, appoint a Person to serve as successor Trustee, provided, that
such Person shall in all respects satisfy the requirements of Section 3807 of
the Act, or any successor provision, and shall be a bank or trust company
incorporated and doing business within the United States of America, whose
business shall consist at least in part as serving as trustee in asset
securitization transactions and having a combined capital and surplus of at
least $150,000,000, if there be such an institution willing, able and legally
qualified to perform the duties of the Trustee hereunder upon reasonable or
customary terms. The appointment of the successor Trustee shall take effect
concurrently with (i) the resignation of the former Trustee and (ii) the
ratification of the Transaction Documents by the successor trustee, and no
resignation of a Trustee shall be effective absent the concurrent appointment of
a successor Trustee.

                  (b) If a successor Trustee shall not have been appointed
within 60 days after such notice of resignation, the Trustee or the Required
Certificateholders may apply to any court of competent jurisdiction to appoint a
successor Trustee to act until such time as a successor shall have been
appointed as above provided.

                                       34
<PAGE>

                  (c) Any corporation into which the Trustee may be merged or
converted or with which it may be consolidated, or any corporation resulting
from any merger, conversion or consolidation to which the Trustee shall be a
party, or any corporation to which substantially all the corporate trust
business of the Trustee may be transferred, shall, subject to such corporation
satisfying in all respects the requirements set forth in Section 9.05(a), be the
Trustee hereunder without further action.

                  (d) Upon the substitution of the Person serving as Trustee,
the successor Trustee, and, if necessary, the holder of the El Paso Interest and
the Required Certificateholders shall file an amendment to the Certificate of
Trust with the Secretary of State in accordance with the provisions of Section
3810 of the Act, indicating the change in the Trustee.

                  Section 9.06. Liability. Wilmington Trust Company shall not be
personally liable under any circumstances, except (a) for its own bad faith,
willful misconduct or gross negligence, (b) in the case of the inaccuracy of any
representation or warranty contained in Section 9.04, (c) for liabilities
arising from the failure by Wilmington Trust Company to perform obligations
expressly undertaken by it in the last sentence of Section 9.01(d) or (d) for
taxes, fees or other charges on, based on or measured by any fees, commissions
or compensation received by the Trustee in connection with any of the
transactions contemplated by this Agreement. In particular, but not by way of
limitation:

                  (i) the provisions of this Agreement, to the extent that they
         restrict the duties and liabilities of Wilmington Trust Company
         otherwise existing at law or in equity, replace such other duties or
         liabilities of Wilmington Trust Company to the extent permissible under
         law or in equity and

                  (ii) Wilmington Trust Company shall not be personally liable
         for the default or misconduct of the Certificateholders.

                  Section 9.07. Indemnification. The holder of the El Paso
Interest shall indemnify, pay, protect, and hold harmless each of Wilmington
Trust Company, its officers, directors, employees, shareholders and agents
(collectively, the "Indemnified Trustee Persons" or individually an "Indemnified
Trustee Person") from and against any and all liabilities, obligations, losses,
damages, actions, judgments, suits, proceedings, taxes, costs, expenses and
disbursements of any kind or nature whatsoever including, without limitation,
all reasonable legal fees, third party costs and expenses of defense, appeal and
settlement of any and all suits, actions, or proceedings instituted against such
Indemnified Trustee Person or the Trust and all reasonable third party costs of
investigation in connection therewith that may be imposed on, incurred by, or
asserted against an Indemnified Trustee Person relating to or arising out of any
action or inaction on the part of the Trust or an Indemnified Trustee Person in
respect of the Trust. Notwithstanding the foregoing, the holder of the El Paso
Interest shall not be liable to any such Indemnified Trustee Person for any of
the matters set forth in clauses (a) through (d) of the first sentence of
Section 9.06. If any action, suit, or proceeding shall be pending against the
Trust and/or one or more Indemnified Trustee Persons relating to or arising out
of any action or inaction of the Indemnified Trustee Person or Indemnified
Trustee Persons, the holder of the El Paso Interest shall have the right to
assume the defense of the Indemnified Trustee Person or Indemnified Trustee
Persons in which case such defense shall be conducted by counsel chosen

                                       35
<PAGE>

by the holder of the El Paso Interest and reasonably satisfactory to the
Indemnified Trustee Person or Indemnified Trustee Persons; provided, however,
that if an Indemnified Trustee Person is advised by its counsel that due to
actual or potential conflicting interests representation by the same counsel
would be inappropriate under applicable standards of professional conduct, such
Indemnified Trustee Person may, at the expense of the Trust, employ separate
counsel of its choice with respect to which such conflicting interest arise in
any such action. The indemnities contained in this Section 9.07 shall survive
the resignation of the Trustee, the termination of the Trust or the termination
of this Agreement.

                  Section 9.08. Fees and Expenses. All reasonable out-of pocket
expenses, disbursements and advances incurred or made by Wilmington Trust
Company, in its capacity as Trustee or Securities Intermediary hereunder,
including without limitation, costs and expenses of winding up, liquidation and
termination of the Trust shall be paid (a) from the Administrative Expenses
distributed to the Trustee by the Indenture Trustee pursuant to Section 5.04 of
the Indenture; provided that the Trustee shall give notice to the Indenture
Trustee of the amount of such expenses, disbursements and advances due and owing
to the Trustee and the Securities Intermediary no later than three Business Days
prior to each Payment Date, (b) from Additional Financing Costs distributed to
the Trust pursuant to Section 6.10 of the Chaparral LLC Agreement or (c) if the
amounts distributed pursuant to the foregoing clauses (a) and (b) are
insufficient, by the holder of the El Paso Interest. Wilmington Trust Company
shall receive as compensation for its services as Trustee and Securities
Intermediary hereunder such ordinary fees as are separately agreed upon between
Wilmington Trust Company and the holder of the El Paso Interest in a separate
fee agreement. Wilmington Trust Company, in its capacity as Trustee and
Securities Intermediary hereunder, shall be compensated reasonably for any
extraordinary services rendered by it hereunder as agreed to separately by the
holder of the El Paso Interest and Wilmington Trust Company.

                  Section 9.09. Litigation, Action Outside Delaware. (a) The
Trustee shall not be under any obligation to appear in, prosecute or defend any
action that in its opinion may require it to incur any out-of-pocket expense or
any liability, unless it shall be furnished with specific instruction from the
Majority Certificateholders and such reasonable security and indemnity against
such expense or liability as it may require, and any reasonable out-of-pocket
costs of the Trustee as a result of such actions shall be paid by the holder of
the El Paso Interest.

                  (b) Notwithstanding anything contained herein to the contrary,
Wilmington Trust Company shall not be required to take any action in any
jurisdiction other than in the State of Delaware if the taking of such action
will (i) require the consent or approval or authorization or order of or the
giving of notice to, or the registration with or the taking of any other action
in respect of, any state or other governmental authority or agency of any
jurisdiction other than the State of Delaware; (ii) result in any fee, tax or
other governmental charge under the laws of any jurisdiction or any political
subdivisions thereof in existence on the Effective Date other than the State of
Delaware becoming payable by Wilmington Trust Company; or (iii) subject
Wilmington Trust Company to personal jurisdiction in any jurisdiction other than
the State of Delaware for causes of action arising from acts unrelated to the
consummation of the transactions by Wilmington Trust Company contemplated
hereby.

                                       36
<PAGE>

                  Section 9.10. Rights of the Securities Intermediary. The
Securities Intermediary shall be entitled to all of the same rights,
protections, immunities and indemnities as the Trustee under this Agreement and
the other Transaction Documents.

                  Section 9.11. Resignation; Appointment of Successor Securities
Intermediary.

                  (a) The Securities Intermediary shall resign if it fails to
meet the requirements of the first sentence of Section 6.02(a)(ii), and such
resignation shall take effect upon receipt by the Trust of an instrument of
acceptance of appointment executed by a successor Securities Intermediary as
herein provided in Sections 9.12 and 9.13.

                  (b) If at any time the Securities Intermediary shall resign,
the Trust shall use its best efforts to locate and recommend a qualified
successor Securities Intermediary and a successor Securities Intermediary may be
appointed by the Trust (whether or not such successor shall have been located or
recommended by the Trust) upon written notice to the Securities Intermediary. In
the event that no such successor Securities Intermediary is appointed by the
Trust within 30 days after the giving of a notice of resignation, the Securities
Intermediary or the Majority Certificateholders may request a court to make such
appointment. Every successor Securities Intermediary appointed pursuant to this
Section 9.11(b) shall be a corporation or association organized under the law of
the United States or any State thereof having a combined capital and surplus of
at least $150,000,000 and a long-term debt rating of at least "A3" by Moody's
and at least "A-" by S&P, if there be such an institution willing and able to
accept the position upon reasonable or customary terms.

                  Section 9.12. Acceptance of Appointment by Successor
Securities Intermediary Any successor Securities Intermediary appointed as
provided in Section 9.11 shall execute, acknowledge and deliver to the Trust and
its predecessor Securities Intermediary an instrument accepting such appointment
hereunder and agreeing to all the provisions regarding the Securities
Intermediary and the Limestone Distribution Account and the Limestone Collection
Account set forth in this Agreement. Subject to the provisions of Section 9.11,
thereupon the resignation of the predecessor Securities Intermediary shall
become effective and such successor Securities Intermediary, without any further
act, deed or conveyance, shall become vested with all the rights, powers, duties
and obligations of its predecessor hereunder, with like effect as if originally
named as Securities Intermediary herein; but, nevertheless, at the written
request of the successor Securities Intermediary, the Securities Intermediary
ceasing to act shall execute and deliver an instrument transferring to such
successor Securities Intermediary all the rights and powers of the Securities
Intermediary so ceasing to act.

                  Section 9.13. Merger or Consolidation of Securities
Intermediary. Any corporation into which the Securities Intermediary may be
merged or converted or with which it may be consolidated or any corporation
resulting from any merger, conversion or consolidation to which the Securities
Intermediary shall be a party shall be the successor of the Securities
Intermediary hereunder; provided that such corporation shall be qualified under
the provisions of

                                       37
<PAGE>

the first sentence of Section 6.02(a)(ii), without the execution or filing of
any paper or any further act on the part of any of the parties hereto or the
Certificateholders, notwithstanding anything contained herein to the contrary.

                                    ARTICLE X

              DISSOLUTION, BANKRUPTCY AND LIQUIDATION OF THE TRUST

                  Section 10.01. Dissolution of the Trust. (a) The Trust shall
be dissolved, wound up and terminated as provided herein upon the Trustee's
determination, in its sole discretion after consultation with such counsel and
other experts as it deems necessary, that the Trust is insolvent. Upon any such
determination, the Trustee shall have the right, in its sole discretion, to (i)
apply for or consent to the appointment of, or the taking of possession by, a
receiver, custodian, trustee, examiner or liquidator of the Trust or of all or a
substantial part of the Trust Estate, (ii) make a general assignment for the
benefit of the Trust's creditors, (iii) file a petition seeking to take
advantage of any other law relating to bankruptcy, insolvency, reorganization,
liquidation, dissolution, arrangement or winding-up, or composition or
readjustment of debts, (iv) take any action for the purpose of effecting any of
the foregoing or (v) do the equivalent of any of the foregoing under the laws of
the United States or of any state or other jurisdiction therein, or of any other
jurisdiction (domestic or foreign) (each action described in (i) through (v), a
"Bankruptcy Action"), each with respect to the Trust upon 90 days' prior written
notice to the Certificateholders and the holder of the El Paso Interest. Neither
the holder of the El Paso Interest nor any Certificateholder shall have any
right to direct the taking of a Bankruptcy Action with respect to the Trust;
provided, however, the Certificateholders shall have the right, subject to the
prior written consent of the holder of the El Paso Interest as provided in
Section 8.05, to liquidate the assets of the Trust on a date that is at least
one year and one day after the Trustee shall have received (x) a certificate
from the Indenture Trustee that all of the obligations under the Indenture have
been satisfied and discharged in full and (y) a certificate from the New
Indenture Trustee that all of the obligations under the New Indenture have been
satisfied and discharged in full. With respect to any determination of
discretion by the Trustee under this Section 10.01(a), the Trustee shall incur
no personal liability to any Person for any determination (or action or inaction
in connection therewith) made in good faith, and in acting (or not in acting as
the case may be) under this Section, the Trustee shall owe no fiduciary duties
to any Person other than the Trust, the Certificateholders, the holder of the El
Paso Interest and any creditors of the Trust. In connection with the Trustee's
determination that the Trust is insolvent, the Trustee shall not be obligated to
follow the instructions of the Certificateholders and shall have no liability to
the Trust or any other Person for its failure to do so.

                  (b) Upon liquidation of the Trust, the Trust's assets shall be
applied in the following order of priority: (i) first, (A) to pay the costs and
expenses of winding up, liquidation and termination of the Trust, including
amounts owed to the Trustee, (B) to creditors of the Trust or (C) to establish
reserves reasonably adequate to meet any and all contingent or unforeseen
liabilities or obligations of the Trust as reasonably determined by the Trustee
in accordance with Applicable Law, in each case, in the order of priority
provided by law; (ii) second, to the Certificateholders, pro rata, until they
have received payments in an aggregate amount equal to the Certificate Purchase
Amount; and (iii) the assets (if any) of the Trust remaining after

                                       38
<PAGE>

distribution as set forth in clauses (i) and (ii) shall, following cancellation
or deemed cancellation of all Limestone Certificates outstanding pursuant to
Section 7.04, be distributed to the holder of the El Paso Interest.

                  Section 10.02. Termination. The Trust shall terminate upon the
earlier of (a) the 10th anniversary of the Closing Date, (b) the date when all
of the Trust's assets shall have been disposed of and distributed as provided
herein and (c) the election of the holder of the El Paso Interest following the
date upon which all Limestone Certificates shall have been cancelled pursuant to
Section 7.04. Upon the winding up of the Trust and its termination, the Trustee
shall cause the Certificate of Trust to be cancelled by filing a certificate of
cancellation with the Secretary of State in accordance with the provisions of
Section 3810 of the Act. Upon such termination, all outstanding Limestone
Certificates shall be cancelled.

                                   ARTICLE XI

                                     NOTICES

                  Section 11.01. Notices. Except as otherwise expressly provided
herein in any particular case, all notices, approvals, consents, requests and
other communications hereunder shall be in writing and shall, if addressed as
provided in the following sentence, be deemed to have been given, (i) when
delivered by hand, (ii) one Business Day after being sent by a private
nationally or internationally recognized overnight courier service, or (iii)
when sent by telecopy, if immediately after transmission the sender's facsimile
machine records in writing the correct answer back. Actual receipt at the
address of an addressee, regardless of whether in compliance with the foregoing
is effective notice hereunder. Until otherwise so notified by the respective
parties, all notices, approvals, consents, requests and other communications
shall be addressed to the following addressees:

                  If to El Paso:

                  1001 Louisiana Street
                  Houston, Texas 77002
                  Attention: Tom Kilgore
                  Telecopier No.: (713) 420-7249
                  Telephone No.: (713) 420-5574

                  with a copy to:

                  1001 Louisiana Street
                  Houston, Texas 77002
                  Attention: Kelly Jameson
                  Telecopier No.: (713) 420-4099
                  Telephone No.: (713) 420-2017

                                       39
<PAGE>

                  If to the Trustee, the Securities Intermediary or the Trust:

                  c/o Wilmington Trust Company
                  Rodney Square North
                  1100 North Market Street
                  Wilmington, Delaware 19890-0001
                  Attention: Corporate Trust Administration
                  Telecopier No.: (302) 651-8882
                  Telephone No.: (302) 651-8681

                  If to the Certificateholders:

                  To the Certificateholders identified as such in the
                  Certificate Register, at the addresses specified in Schedule I
                  to the Participation Agreement or in the Investment
                  Certificate, as applicable.

                                   ARTICLE XII

                            MISCELLANEOUS PROVISIONS

                  Section 12.01. Entire Agreement. This Agreement (including,
without limitation, the exhibits hereto) and the other Transaction Documents,
and each of the parties hereto represents and warrants to the others that this
Agreement constitutes the entire agreement among the parties hereto relating to
the transactions contemplated hereby.

                  Section 12.02. Governing Law. THIS AGREEMENT SHALL BE GOVERNED
BY AND CONSTRUED AND ENFORCED IN ACCORDANCE WITH THE LAWS OF THE STATE OF
DELAWARE; PROVIDED THAT THERE SHALL NOT BE APPLICABLE TO THE TRUST, THE PARTIES
HEREUNDER OR THIS AGREEMENT, ANY PROVISION OF THE LAWS (COMMON OR STATUTORY) OF
THE STATE OF DELAWARE PERTAINING TO TRUSTS (OTHER THAN THE ACT) THAT RELATE TO
OR REGULATE, IN A MANNER INCONSISTENT WITH THE TERMS HEREOF, (A) THE FILING WITH
ANY COURT OR GOVERNMENTAL BODY OR AGENCY OF TRUSTEE ACCOUNTS OR SCHEDULES OF
TRUSTEE FEES AND CHARGES, (B) AFFIRMATIVE REQUIREMENTS TO POST BONDS FOR
TRUSTEES, OFFICERS, AGENTS OR EMPLOYEES OF A TRUST, (C) THE NECESSITY FOR
OBTAINING COURT OR OTHER GOVERNMENTAL APPROVAL CONCERNING THE ACQUISITION,
HOLDING OR DISPOSITION OF REAL OR PERSONAL PROPERTY, (D) FEES OR OTHER SUMS
PAYABLE TO TRUSTEES, OFFICERS, AGENTS OR EMPLOYEES OF A TRUST, (E) THE
ALLOCATION OF RECEIPTS AND EXPENDITURES TO INCOME OR PRINCIPAL, (F) RESTRICTIONS
OR LIMITATIONS ON THE PERMISSIBLE NATURE, AMOUNT OR CONCENTRATION OF TRUST
INVESTMENTS OR REQUIREMENTS RELATING TO THE TITLING, STORAGE OR OTHER MANNER OF
HOLDING OR INVESTING TRUST ASSETS OR (G) THE ESTABLISHMENT OF FIDUCIARY OR OTHER
STANDARDS OF RESPONSIBILITY OR LIMITATIONS ON THE ACTS OR POWERS OF THE TRUSTEE

                                       40
<PAGE>

THAT ARE INCONSISTENT WITH THE LIMITATIONS OR AUTHORITIES AND POWERS OF THE
TRUSTEE HEREUNDER AS SET FORTH OR REFERENCED IN THIS AGREEMENT. SECTION 3540 OF
TITLE 12 OF THE DELAWARE CODE SHALL NOT APPLY TO THE TRUST.

                  Section 12.03. Severability of Provisions. If any provision
hereof shall be held invalid or unenforceable by any court of competent
jurisdiction, such holding shall not invalidate or render unenforceable any
other provision hereof. To the extent permitted by Applicable Law, the parties
hereto hereby agree that any provision hereof that renders any other term or
provision hereof invalid or unenforceable in any respect shall be modified, but
only to the extent necessary to avoid rendering such other term or provision
invalid or unenforceable, and such modification shall be accomplished in the
manner that most nearly preserves the benefit of all the parties' bargain
hereunder.

                  Section 12.04. Amendment or Waiver; Effect on Agreement. Any
provision of this Agreement may be amended or waived by an amendment or waiver
which is in writing and signed by the holder of the El Paso Interest and the
Trustee; provided, that the Trustee shall consent to any amendment or waiver
only upon instruction by the Majority Certificateholders; provided, further,
that without the consent of 100% of the Certificateholders at the time, no such
amendment or waiver or any amendment or waiver to any other Transaction Document
to which the Trust is a party shall (1) alter or amend the right of the
Certificateholders to receive payments thereon, or institute suit in respect
thereof, (2) release any portion of the Trust Estate or any portion of the
assets of the Trust, (3) reduce any amount required to be collected or retained
by the Trust or the Trustee or (4) release the Guarantor from any of its
obligations under the El Paso Guarantee or reduce the amount of the Guaranteed
Obligations.

                  Promptly after the execution by all required parties of any
such amendment to, or waiver of, this Agreement, the Trustee shall furnish a
copy of any such amendment or waiver to each Certificateholder and the holder of
the El Paso Interest.

                  Section 12.05. Binding Upon Assigns. Except as otherwise
provided herein, the provisions of this Agreement (including any amendments,
modification and waivers hereof properly adopted) shall be binding upon and
shall inure to the benefit of the parties hereto and their respective successors
and assigns.

                  Section 12.06. Survival. All agreements, representations,
warranties and indemnities contained in this Agreement and in any agreement,
document or certificate delivered pursuant hereto, or in connection herewith,
shall survive and continue in effect following the execution and delivery of
this Agreement and the Closing Date. Upon the repayment in full of the Limestone
Certificates, this Agreement shall terminate except as to those provisions,
including without limitation, Section 9.07 hereof, expressly intended to survive
such termination.

                  Section 12.07. Tax Characterization. (a) Each of the parties
hereto recognizes and intends that, for United States federal, state and local
income tax purposes,

                           (i) the Trust will not be treated as an association
         taxable as a corporation;

                                       41
<PAGE>

                           (ii) the Limestone Certificates will either be
         disregarded or treated as equity interests in the Trust; and

                           (iii) the El Paso Interest will be disregarded until
         such time as the holder of the El Paso Interest exercises its rights,
         makes a contribution or is deemed to make a contribution pursuant to
         Section 3.03.

                  (b) To the extent that any of the parties hereto is required
to report any item of income, gain, loss, deduction or credit relating to the
Trust for United States federal, state or local income tax purposes, such party
shall report such item in a manner consistent with the characterization intended
by this Section 12.07 and shall not take any contrary position on any tax return
or report relating to the United States federal, state or local income taxes or
take any other action which is inconsistent with such characterization.

                  (c) Notwithstanding anything to the contrary herein, no party
shall be obligated to take a position subsequent to (A) a Final Determination to
the contrary or (B) a written opinion of independent, nationally-recognized tax
counsel selected by such party (such counsel and form of opinion to be
reasonably satisfactory to the holder of the El Paso Interest) that no
Reasonable Basis exists to take such position, which opinion shall, solely in
the case of a United States federal income Tax return, be based on a Change in
Law, provided, however, that a court decision described in clause (iii) of the
definition of "Change in Law" shall not constitute a Change in Law if the holder
of the El Paso Interest provides to the relevant party a written opinion of
independent, nationally-recognized tax counsel selected by the holder of the El
Paso Interest (such counsel and form of opinion to be reasonably satisfactory to
such party) that, notwithstanding such decision, such party's position is more
likely than not to prevail if challenged.

                  Section 12.08. Counterparts. This Agreement may be executed in
any number of counterparts, each of which shall be deemed to be an original, but
all such counterparts shall together constitute but one and the same instrument.

                  Section 12.09. Effectiveness. This Agreement shall take effect
on and as of the Effective Date.

                                       42
<PAGE>
                  IN WITNESS WHEREOF, the undersigned have executed this
Agreement as of the date above first written.

                                    WILMINGTON TRUST COMPANY,
                                      as Trustee

                                    By: /s/ Ann E. Roberts
                                        ----------------------------------------
                                        Name:  Ann E. Roberts
                                        Title: Assistant Vice President

                                    ELECTRON TRUST,
                                      as sole Certificateholder

                                    By: Wilmington Trust Company, not in its
                                        individual capacity, but solely as
                                        Trustee

                                    By: /s/ Ann E. Roberts
                                        ----------------------------------------
                                        Name:  Ann E. Roberts
                                        Title: Assistant Vice President

                                    LIMESTONE ELECTRON TRUST

                                    By: Wilmington Trust Company, not in its
                                        individual capacity, but solely as
                                        Trustee

                                        By: /s/ Ann E. Roberts
                                            ------------------------------------
                                            Name:  Ann E. Roberts
                                            Title: Assistant Vice President

                           Limestone Trust Agreement
<PAGE>
                                   WILMINGTON TRUST COMPANY,
                                     as Securities Intermediary for the purposes
                                     of Sections 6.02, 6.03, 6.04, 9.10, 9.11,
                                     9.12 and 9.13 only

                                   By: /s/ Ann E. Roberts
                                       ----------------------------------------
                                       Name:  Ann E. Roberts
                                       Title: Assistant Vice President

                                   EL PASO CORPORATION,
                                   as holder of the El Paso Interest

                                   By: /s/ Thomas G. Kilgore
                                       ----------------------------------------
                                       Name:  Thomas G. Kilgore
                                       Title: Vice President

                           Limestone Trust Agreement<PAGE>
                                                                 EXHIBIT 10.BB.5
================================================================================

                                    INDENTURE

                           dated as of April 26, 2002

                                      among

                            LIMESTONE ELECTRON TRUST,

                                     Issuer,

                            LIMESTONE ELECTRON, INC.,

                                   Co-Issuer,

                              THE BANK OF NEW YORK,

                              New Indenture Trustee

                                       and

                              EL PASO CORPORATION,

                                    Guarantor

                8.625% Guaranteed Senior Unsecured Notes due 2003

================================================================================

<PAGE>

                                TABLE OF CONTENTS

<Table>
<Caption>
                                                                                                               Page

<S>                                                                                                            <C>
ARTICLE I  DEFINITIONS............................................................................................1
         SECTION 1.01.         Definitions........................................................................1
         SECTION 1.02.         Rules of Construction..............................................................8
         SECTION 1.03.         Legal Holidays.....................................................................8
         SECTION 1.04.         Compliance Certificates and Opinions...............................................8
         SECTION 1.05.         Form of Documents Delivered to Trustee.............................................8

ARTICLE II  THE LIMESTONE NOTES...................................................................................9
         SECTION 2.01.         Forms Generally....................................................................9
         SECTION 2.02.         Authorized Amount; Interest Rate; Maturity Date; Denominations....................10
         SECTION 2.03.         Execution, Authentication, Delivery and Dating....................................10
         SECTION 2.04.         Registrar and Paying Agent; Registration..........................................11
         SECTION 2.05.         Payments of Principal and Interest; Rights Preserved..............................12
         SECTION 2.06.         Transfer and Exchange of New Limestone Notes......................................15
         SECTION 2.07.         Replacement of Lost, Mutilated or Stolen New Limestone Notes......................20
         SECTION 2.08.         Taxes.............................................................................20
         SECTION 2.09.         Cancellation......................................................................21

ARTICLE III  GUARANTEE OF NEW LIMESTONE NOTES....................................................................21
         SECTION 3.01.         El Paso Guarantee.................................................................21
         SECTION 3.02.         Obligations Unconditional.........................................................22
         SECTION 3.03.         Limitation of Guarantor's Liability...............................................23
         SECTION 3.04.         Subordination of Subrogation and Other Rights.....................................23
         SECTION 3.05.         Execution and Delivery of El Paso Guarantee.......................................23
         SECTION 3.06.         Notice to New Indenture Trustee...................................................23
         SECTION 3.07.         This Article Not to Prevent Events of Default.....................................23
         SECTION 3.08.         New Notes Liquidity Payment.......................................................23
         SECTION 3.09.         Additional Optional Payments by Guarantor.........................................24

ARTICLE IV  ISSUANCE.............................................................................................24
         SECTION 4.01.         Conditions to Issuance............................................................24
         SECTION 4.02.         [Reserved]........................................................................25
         SECTION 4.03.         Waiver of Conditions to Issuance..................................................25

ARTICLE V  THE ACCOUNT...........................................................................................25
         SECTION 5.01.         Establishment of New Notes Account................................................25
         SECTION 5.02.         New Notes Account.................................................................26
         SECTION 5.03.         Shortfall.........................................................................26
         SECTION 5.04.         Payments..........................................................................26
         SECTION 5.05.         Report to New Noteholders.........................................................29
         SECTION 5.06.         Termination.......................................................................30

ARTICLE VI  REPRESENTATIONS AND WARRANTIES OF THE ISSUERS........................................................30
         SECTION 6.01.         Representations and Warranties....................................................30
         SECTION 6.02.         Survival of Representations and Warranties........................................33
</Table>

<PAGE>

<Table>
<S>                                                                                                            <C>
ARTICLE VII  COVENANTS OF THE ISSUERS AND THE GUARANTOR..........................................................33
         SECTION 7.01.         Covenants of the Issuers and the Guarantor........................................33

ARTICLE VIII  LIMITATION ON LIABILITY OF THE ISSUERS.............................................................41
         SECTION 8.01.         Liabilities of the Issuers........................................................41

ARTICLE IX  EVENTS OF DEFAULT....................................................................................41
         SECTION 9.01.         Events of Default.................................................................41
         SECTION 9.02.         Application of Proceeds...........................................................43
         SECTION 9.03.         Waiver of Past Events of Default..................................................43
         SECTION 9.04.         Provisions Relating to Recourse for the Notes.....................................43

ARTICLE X  SATISFACTION AND DISCHARGE OF NEW INDENTURE; NOTICE OF CERTAIN EVENTS; UNCLAIMED MONEYS...............45
         SECTION 10.01.        Satisfaction and Discharge of New Indenture.......................................45
         SECTION 10.02.        Reserved..........................................................................46
         SECTION 10.03.        Repayment of Moneys and Transfer of Eligible Investments Held by
                               New Indenture Trustee.............................................................46
         SECTION 10.04.        Return of Moneys Held by New Indenture Trustee....................................46

ARTICLE XI  CONCERNING THE NEW INDENTURE TRUSTEE.................................................................46
         SECTION 11.01.        Duties of the New Indenture Trustee; Certain Rights of the New
                               Indenture Trustee.................................................................46
         SECTION 11.02.        Performance of New Indenture Trustee's Duties.....................................48
         SECTION 11.03.        Resignation and Removal; Appointment of Successor New Indenture
                               Trustee...........................................................................49
         SECTION 11.04.        Acceptance of Appointment by Successor New Indenture Trustee......................49
         SECTION 11.05.        Merger or Consolidation of New Indenture Trustee..................................49
         SECTION 11.06.        Certain Procedural Matters........................................................50
         SECTION 11.07.        New Indenture Trustee Fees and Indemnification....................................50
         SECTION 11.08.        Information.......................................................................51
         SECTION 11.09.        Eligibility Requirements for New Indenture Trustee................................51
         SECTION 11.10.        New Indenture Trustee Not Liable for New Limestone Notes..........................51
         SECTION 11.11.        New Indenture Trustee May Own New Limestone Notes.................................51
         SECTION 11.12.        Maintenance of Office or Agency...................................................51
         SECTION 11.13.        Appointment of Co-Indenture Trustee...............................................51
         SECTION 11.14.        [Reserved]........................................................................52
         SECTION 11.15.        [Reserved]........................................................................52
         SECTION 11.16.        [Reserved]........................................................................52

ARTICLE XII  SUPPLEMENTAL NEW INDENTURES.........................................................................52
         SECTION 12.01.        Supplemental New Indentures Without Consent of New Noteholders....................52
         SECTION 12.02.        Supplemental New Indentures With Consent of New Noteholders.......................52
         SECTION 12.03.        Effect of Supplemental New Indenture..............................................53
         SECTION 12.04.        Documents to Be Given to New Indenture Trustee....................................53
         SECTION 12.05.        Notation on New Limestone Notes in Respect of Supplemental New
                               Indentures........................................................................53
</Table>

                                       ii
<PAGE>

<Table>
<S>                                                                                                            <C>
ARTICLE XIII  CONCERNING THE NEW HOLDERS.........................................................................54
         SECTION 13.01.        Control by Majority New Holders...................................................54
         SECTION 13.02.        Evidence of Action Taken by New Holders...........................................54
         SECTION 13.03.        Proof of Execution of Instruments.................................................54
         SECTION 13.04.        New Limestone Notes Owned by the Issuers..........................................54
         SECTION 13.05.        Right of Revocation of Action Taken...............................................55

ARTICLE XIV  OPTIONAL REDEMPTION.................................................................................55
         SECTION 14.01.        Optional Redemption...............................................................55
         SECTION 14.02.        Notice of Optional Redemption.....................................................56
         SECTION 14.03.        Selection of New Limestone Notes to be Redeemed...................................57
         SECTION 14.04.        Deposit of Optional Redemption Price..............................................57
         SECTION 14.05.        Payment of New Limestone Notes Called for Optional Redemption.....................58
         SECTION 14.06.        New Notes Redeemed in Part........................................................58

ARTICLE XV  MANDATORY REDEMPTION AND SPECIAL REDEMPTION..........................................................58
         SECTION 15.01.        Mandatory Redemption..............................................................58
         SECTION 15.02.        Notice of Mandatory Redemption....................................................59
         SECTION 15.03.        Selection of New Limestone Notes to be Redeemed...................................59
         SECTION 15.04         Special Redemption................................................................59
         SECTION 15.05.        Notice of Special Redemption......................................................60
         SECTION 15.06.        Selection of New Limestone Notes to be Redeemed...................................60

ARTICLE XVI  MISCELLANEOUS.......................................................................................61
         SECTION 16.01.        Survival..........................................................................61
         SECTION 16.02.        Notices...........................................................................61
         SECTION 16.03.        Severability of Provisions........................................................62
         SECTION 16.04         Effect of Headings................................................................63
         SECTION 16.05.        Counterparts......................................................................63
         SECTION 16.06.        Further Assurance.................................................................63
         SECTION 16.07         Governing Law; Waiver of Jury Trial...............................................63
         SECTION 16.08.        Entire Agreement..................................................................64
         SECTION 16.09.        Benefit of Agreement..............................................................64
         SECTION 16.10.        Limitation on Rights of New Noteholders...........................................65
         SECTION 16.11.        [Reserved]........................................................................65
         SECTION 16.12.        Limitation of Liability of Wilmington Trust Company...............................65
         SECTION 16.13.        New Limestone Notes Non-Assessable and Fully Paid.................................65
</Table>

         Exhibit A         Form of Rule 144A Note
         Exhibit B         Reserved
         Exhibit C         Form of Certificate of Transfer
         Exhibit D         Form of Important Notice
         Exhibit E         Form of Section 3(c)(7) Reminder Notice
         Exhibit F         Form of Default Notice
         Exhibit G         Form of El Paso Guarantee

                                       iii
<PAGE>

                                    INDENTURE

                  This INDENTURE (hereinafter, this "New Indenture"), dated as
of April 26, 2002, is among LIMESTONE ELECTRON TRUST, a Delaware business trust
("Limestone"), LIMESTONE ELECTRON, INC., a Delaware corporation (the "Co-Issuer"
and, together with Limestone, the "Issuers"), THE BANK OF NEW YORK, a New York
banking corporation (in its capacity as indenture trustee, the "New Indenture
Trustee") and EL PASO CORPORATION, a Delaware corporation (in its capacity as
guarantor, the "Guarantor").

                                   WITNESSETH:

                  WHEREAS, pursuant to a Participation Agreement dated as of
March 15, 2000 (as amended, supplemented, amended and restated or otherwise
modified from time to time, the "Participation Agreement") among El Paso,
Limestone, Credit Suisse First Boston (USA), Inc., as successor to DLJ Inc., El
Paso Chaparral Holding, El Paso Chaparral, El Paso Chaparral Holding II, the
Management Company, Chaparral, Mesquite, the Overfund Trust, the Share Trust,
Electron, Wilmington Trust Company and The Bank of New York, as successor to
United States Trust Company of New York (each as defined therein), the Issuers
have issued, offered and sold the Limestone Notes;

                  WHEREAS, the Issuers have authorized the issuance of up to
$1,000,000,000 aggregate principal amount of their 8.625% Guaranteed Senior
Unsecured Notes due 2003 (together with the El Paso Guarantee endorsed thereon,
the "New Limestone Notes"), the payments of which will be guaranteed by the El
Paso Guarantee, to be exchanged for up to $1,000,000,000 aggregate principal
amount of the Limestone Notes;

                  WHEREAS, the execution and delivery of this New Indenture has
been duly authorized by the Issuers and the Guarantor;

                  WHEREAS, the New Indenture Trustee has accepted the trusts
created by this New Indenture and in evidence thereof has joined in the
execution hereof;

                  WHEREAS, all things necessary to make the New Limestone Notes,
when issued and authenticated by the New Indenture Trustee as contemplated in
this New Indenture, the legal, valid and binding obligations of the Issuers have
been done and performed; and

                  WHEREAS, all things necessary to make the El Paso Guarantee
the legal, valid and binding obligation of the Guarantor have been done and
performed.

                  NOW, THEREFORE, THIS NEW INDENTURE WITNESSETH, that for good
and valuable consideration the receipt and sufficiency of which is hereby
acknowledged, and for the purpose of fixing and declaring the terms and
conditions upon which the New Limestone Notes are to be issued, authenticated,
delivered, guaranteed and accepted by all Persons who shall from time to time be
or become holders thereof, the Issuers, the Guarantor and the New Indenture
Trustee, for the benefit of the holders of the New Limestone Notes, agree as
follows:

                                    ARTICLE I

                                   DEFINITIONS

                  SECTION 1.01. Definitions. References to "Sections" and
"Articles" herein refer to Sections and Articles of this New Indenture unless
otherwise stated. Unless otherwise defined herein or unless the context shall
otherwise require, capitalized terms used in this New Indenture shall have the

<PAGE>

meanings assigned to such terms in Annex A to the Participation Agreement.
Whenever used in this New Indenture, the following words and phrases, unless the
context otherwise requires, shall have the following meanings:

                  "Acceleration Date" means any date on which the maturity of
the New Limestone Notes is accelerated in accordance with Section 9.01.

                  "Account Statement" has the meaning assigned to such term in
Section 5.05.

                  "Amount Available" means, with respect to the New Notes
Account, the amount in Cash credited to the New Notes Account.

                  "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.

                  "Authentication Order" means an order executed by the Issuers
and addressed to the New Indenture Trustee for the authentication and delivery
of the New Limestone Notes.

                  "Certificate of Authentication" has the meaning assigned to
such term in Section 2.03(f).

                  "Clearstream" means Clearstream Banking, societe anonyme.

                  "Comparable Treasury Issue" means the United States Treasury
security selected by an Independent Investment Banker as having a maturity
comparable to the remaining term of the applicable securities that would be
utilized, at the time of selection and in accordance with customary financial
practice, in pricing new issues of corporate debt securities of comparable
maturity to the remaining term of the applicable securities.

                  "Comparable Treasury Price" means, with respect to any
Optional Redemption Date or any Acceleration Date which is attributable to an
Event of Default described in Section 9.01(a), (i) the average of the applicable
Reference Treasury Dealer Quotations for such Optional Redemption Date or
Acceleration Date, as the case may be, after excluding the highest and lowest
such applicable Reference Treasury Dealer Quotations, or (ii) if fewer than four
such Reference Treasury Dealer Quotations are obtained, the average of all such
Quotations.

                  "Consolidated Net Tangible Assets" means, at any date of
determination, the total amount of assets after deducting therefrom (i) all
current liabilities (excluding (A) any current liabilities that by their terms
are extendable or renewable at the option of the obligor thereon to a time more
than 12 months after the time as of which the amount thereof is being computed,
and (B) current maturities of long-term debt) and (ii) the value (net of any
applicable reserves) of all goodwill, trade names, trademarks, patents and other
like intangible assets, all as set forth on the consolidated balance sheet of
the Guarantor and its consolidated subsidiaries for the Guarantor's most
recently completed fiscal quarter, prepared in accordance with GAAP.

                  "Corporate Trust Office" means the principal office of the New
Indenture Trustee at which at any particular time its corporate trust business
shall be administered, which office, at the date of the execution of this New
Indenture, is located at The Bank of New York, 5 Penn Plaza, New York, New York
10001, Attention: Louis P. Young, or any other office specified in writing by
the New Indenture Trustee.

                  "Custodian" has the meaning assigned to such term in Section
2.01(b).

                                       2
<PAGE>

                  "Debt" means any obligation created or assumed by any Person
for the repayment of money borrowed and any purchase money obligation created or
assumed by such Person.

                  "Default Interest Rate" means 2% per annum.

                  "Default Notice" has the meaning assigned to such term in
Section 9.01.

                  "Definitive Notes" means one or more definitive New Limestone
Notes registered in the name of the New Holder thereof and issued in accordance
with Section 2.06, substantially in the form of Exhibit A hereto except that
such New Limestone Notes shall not bear the Global Note Legend and shall not
have the "Schedule of Exchanges of Interests in the Global Note" attached
thereto.

                  "Depositary" means DTC, its nominees and their respective
successors and assigns, or such other depository institution hereinafter
appointed by Limestone.

                  "DTC" means The Depository Trust Company.

                  "El Paso Guarantee" means the guarantee by the Guarantor of
the Issuers' payment obligations under this New Indenture and the New Limestone
Notes pursuant to Article III (other than Section 3.08 and Section 3.09), as
evidenced by an endorsement on the New Limestone Notes.

                  "El Paso Permitted Liens" means (i) Liens upon rights-of-way
for pipeline purposes; (ii) any governmental Lien, mechanics', materialmen's,
carriers' or similar Lien incurred in the ordinary course of business which is
not yet due or which is being contested in good faith by appropriate proceedings
and any undetermined Lien which is incidental to construction; (iii) the right
reserved to, or vested in, any municipality or public authority by the terms of
any right, power, franchise, grant, license, permit or by any provision of law,
to purchase or recapture or to designate a purchaser of, any property; (iv)
Liens of taxes and assessments which are (A) for the then current year, (B) not
at the time delinquent or (C) delinquent but the validity of which is being
contested at the time by the Guarantor or any Subsidiary in good faith; (v)
Liens of, or to secure performance of, leases; (vi) any Lien upon, or deposits
of, any assets in favor of any surety company or clerk of court for the purpose
of obtaining indemnity or stay of judicial proceedings; (vii) any Lien upon
property or assets acquired or sold by the Guarantor or any Restricted
Subsidiary resulting from the exercise of any rights arising out of defaults on
receivables; (viii) any Lien incurred in the ordinary course of business in
connection with workmen's compensation, unemployment insurance, temporary
disability, social security, retiree health or similar laws or regulations or to
secure obligations imposed by statute or governmental regulations; (ix) any Lien
upon any property or assets in accordance with customary banking practice to
secure any Debt incurred by the Guarantor or any Restricted Subsidiary in
connection with the exporting of goods to, or between, or the marketing of goods
in, or the importing of goods from, foreign countries; or (x) any Lien in favor
of the United States or any state thereof, or any other country, or any
political subdivision of any of the foregoing, to secure partial, progress,
advance or other payments pursuant to any contract or statute, or any Lien
securing industrial development, pollution control or similar revenue bonds.

                  "Euroclear" means Morgan Guaranty Trust Company of New York,
Brussels office, as operator of the Euroclear system, or any successor to Morgan
Guaranty Trust Company of New York, Brussels office, as operator thereof.

                  "Events of Default" has the meaning assigned to such term in
Section 9.01.

                  "Excepted Rights" has the meaning assigned to such term in
Section 1.01 of the Indenture; provided that upon the satisfaction and discharge
of the Indenture, the definition of "Excepted Rights" shall continue to have
such meaning as if the Indenture had not been satisfied and discharged (but
without giving effect to any supplement or other modification made in
contemplation of such satisfaction and discharge); provided, further, that any
provisions included in the definition of "Excepted Rights" that

                                       3
<PAGE>

are required for the interpretation thereof and would otherwise terminate upon
the satisfaction and discharge of the Indenture shall also be considered to
continue for the purposes of such interpretation.

                  "Exchange Offer" means the issuance by the Issuers of a
principal amount of New Limestone Notes equal to the outstanding principal
amount of Limestone Notes that are tendered by the Noteholders in exchange for
such New Limestone Notes pursuant to the Offering Circular and Consent
Solicitation Statement.

                  "Funded Debt" means all Debt maturing one year or more from
the date of the creation thereof, all Debt directly or indirectly renewable or
extendible, at the option of the debtor, by its terms or by the terms of any
instrument or agreement relating thereto, to a date one year or more from the
date of the creation thereof, and all Debt under a revolving credit or similar
agreement obligating the lender or lenders to extend credit over a period of one
year or more.

                  "Global Note Legend" has the meaning assigned to such term in
Section 2.06(d)(ii).

                  "Global Notes" means, individually and collectively, one or
more global New Limestone Notes registered in the name of the New Holder thereof
and issued in accordance with Sections 2.01(b) and 2.06, substantially in the
form of Exhibit A hereto.

                  "Guaranteed Obligations" has the meaning assigned to such term
in Section 3.01.

                  "Guarantor" has the meaning assigned to such term in the
introductory paragraph of this New Indenture.

                  "Indebtedness" means (a) indebtedness for borrowed money, (b)
obligations (other than any portion of any trade payable obligation which shall
not have remained unpaid for 91 days or more from the original due date of such
portion) to pay the deferred purchase price of property or services or (c)
obligations as lessee under leases which shall have been or should be, in
accordance with GAAP, recorded as capital leases.

                  "Indenture Default" means any event or occurrence that with
the giving of notice or lapse of time or both would become an Event of Default.

                  "Independent Investment Banker" means CSFB or such other
independent investment banking institution of national or international standing
selected by the New Indenture Trustee.

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

                  "Issuers' Certificate" means a certificate of Limestone
executed on behalf of itself and the Co-Issuer.

                  "Letter of Transmittal" means the letter of transmittal to be
prepared by the Issuers and sent to all Noteholders for use by such Holders in
connection with the Exchange Offer.

                  "Limestone Certificate Yield" means, for any period, the
product of (a) 10.35% per annum and (b) the Limestone Equity Cash Component and
(c) the quotient of (i) the number of days actually elapsed (calculated on the
basis of a 360-day year consisting of twelve 30-day months) since the later of
the Closing Date or the last payment of Limestone Certificate Yield and (ii)
360.

                                       4
<PAGE>

                  "Limestone Interest Amount" means, for any Limestone Note
Payment Date, the product of (a) the Limestone Note Rate, (b) the aggregate
outstanding principal amount of New Limestone Notes and (c) the quotient of (i)
the number of days actually elapsed (calculated on the basis of a 360-day year
consisting of twelve 30-day months) since the last Limestone Note Payment Date
through which the Limestone Interest Amount was paid and (ii) 360.

                  "Limestone Note Payment Date" means: (a) each March 15 and
September 15 commencing September 15, 2002, (b) with respect to an Acceleration
Date, any date following such Acceleration Date on which funds are received for
distribution pursuant to Section 5.04, (c) an Optional Redemption Date, (d) a
Mandatory Redemption Date, (e) a Special Redemption Date and (f) the Maturity
Date.

                  "Limestone Note Rate" means the fixed per annum rate equal to
8.625%.

                  "Majority New Holders" or "Majority New Noteholders" means, at
any time, New Noteholders holding, collectively, New Limestone Notes evidencing
at least a majority in aggregate outstanding principal amount of the New
Limestone Notes.

                  "Mandatory Redemption" has the meaning assigned to such term
in Section 15.01(d).

                  "Mandatory Redemption Date" has the meaning assigned to such
term in Section 15.01(d).

                  "Mandatory Redemption Price" has the meaning assigned to such
term in Section 15.01(d).

                  "Maturity Date" has the meaning assigned to such term in
Section 2.02(c).

                  "New Administrative Expenses" means, without duplication, (a)
the New Indenture Trustee Fee, (b) any New Indenture Trustee Expenses, (c) the
out-of-pocket expenses and fees of the Paying Agents, (d) any indemnity payments
payable by the Issuers and/or the Guarantor to the New Indenture Trustee
pursuant to Section 11.07, (e) any fees and expenses due or payable as of any
Limestone Note Payment Date or Additional Financing Costs Payment Date to each
Rating Agency in connection with any rating or rating estimate of the New
Limestone Notes, as contemplated by the Transaction Documents, and (f) any costs
or expenses payable pursuant to Section 7.01(k).

                  "New Holders" and "New Noteholders" means the registered
holders from time to time of any of the New Limestone Notes.

                  "New Indenture Trustee Expenses" has the meaning assigned to
such term in Section 11.07(a).

                  "New Indenture Trustee Fee" means the initial and annual fee
to be paid to the New Indenture Trustee pursuant to Section 11.07 and in
accordance with a separate fee agreement between Limestone and the New Indenture
Trustee.

                  "New Notes Account" has the meaning assigned to such term in
Section 5.01(a).

                  "New Notes Liquidity Payment" has the meaning assigned to such
term in Section 3.08.

                  "New York UCC" means the Uniform Commercial Code as in effect
from time to time in the State of New York.

                  "Note Register" has the meaning assigned to such term in
Section 2.04(a).

                  "Notice of Mandatory Redemption" has the meaning assigned to
such term in Section 15.02.

                                       5
<PAGE>

                  "Notice of Optional Redemption" has the meaning assigned to
such term in Section 14.02.

                  "Notice of Special Redemption" has the meaning assigned to
such term in Section 15.05.

                  "Officer's Certificate" means a certificate of any Person
signed by any Authorized Officer of such Person.

                  "Opinion of Counsel" means an opinion in writing signed by
legal counsel and delivered to the New Indenture Trustee which counsel may be an
employee of El Paso or other counsel reasonably satisfactory to the New
Indenture Trustee.

                  "Optional Redemption" has the meaning assigned to such term in
Section 14.01(b).

                  "Optional Redemption Date" has the meaning assigned to such
term in Section 14.01(b).

                  "Optional Redemption Price" has the meaning assigned to such
term in Section 14.01(e).

                  "Outstanding" means at any time all New Limestone Notes
authenticated and delivered by the New Indenture Trustee under this New
Indenture except:

                  (a) New Limestone Notes theretofore canceled by the New
Indenture Trustee or delivered to the New Indenture Trustee for cancellation;

                  (b) New Limestone Notes or portions thereof, with respect to
which moneys in the amount necessary to pay such New Limestone Notes or portions
thereof shall have been deposited in trust with the New Indenture Trustee;
provided that if such New Limestone Notes or portions thereof are to be redeemed
prior to the maturity thereof, notice of such redemption shall have been given
as herein provided, or provision satisfactory to the New Indenture Trustee shall
have been made for the giving of such notice; and

                  (c) New Limestone Notes in substitution or exchange for which
other New Limestone Notes shall have been authenticated and delivered.

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

                  "Paying Agent" means any Person authorized by the Issuers to
pay the principal of or interest on any New Limestone Notes on behalf of the
Issuers as specified in Section 2.04(b).

                  "Principal Property" means (a) any pipeline assets of the
Guarantor or any Subsidiary, including any related facilities employed in the
transportation, distribution or marketing of natural gas, that is located in the
United States or Canada and (b) any processing or manufacturing plant owned or
leased by the Guarantor or any Subsidiary and located within the United States
or Canada, except, in the case of either clause (a) or (b), any such assets or
plant which, in the opinion of the board of directors of the Guarantor (or any
committee thereof), is not material in relation to the activities of the
Guarantor and its Subsidiaries as a whole.

                  "QIB" means a "qualified institutional buyer" within the
meaning of Rule 144A.

                  "QP Legend" has the meaning assigned to such term in Section
2.06(d)(iv).

                  "Record Date" has the meaning assigned to such term in Section
5.04(e).

                                       6
<PAGE>

                  "Recourse for the Notes" has the meaning assigned to such term
in Section 2.05(f).

                  "Reference Treasury Dealer" means a primary U.S. Government
securities dealer in New York City as an Independent Investment Banker shall
select at the request of the New Indenture Trustee.

                  "Reference Treasury Dealer Quotations" means, with respect to
each Optional Redemption Date or any Acceleration Date which is attributable to
an Event of Default described in Section 9.01(a), the average, as determined by
an Independent Investment Banker, of the bid and asked prices for the Comparable
Treasury Issue for the New Limestone Notes (expressed in each case as a
percentage of its principal amount or stated amount, as the case may be), quoted
in writing by at least four Reference Treasury Dealers at 5:00 p.m. on the third
Business Day preceding such Optional Redemption Date or Acceleration Date.

                  "Registrar" has the meaning assigned to such term in Section
2.04(a).

                  "Restricted Definitive Notes" means a Definitive Note bearing
the Transfer Restriction Legend.

                  "Restricted Global Note" means a Global Note bearing the
Transfer Restriction Legend.

                  "Restricted Subsidiary" means any Subsidiary of the Guarantor
owning or leasing any Principal Property.

                  "Rule 144A" means Rule 144A under the Securities Act.

                  "Rule 144A Global Note" means one or more permanent global
notes substantially in the form of Exhibit A hereto bearing the Global Note
Legend, the Transfer Restriction Legend and the QP Legend and deposited with or
on behalf of, and registered in the name of, the Depositary, issued in an
aggregate denomination equal to the outstanding principal amount of the New
Limestone Notes issued in exchange for Limestone Notes acquired pursuant to Rule
144A under the Indenture (in accordance with the Exchange Offer).

                  "Rule 144A Note" means any New Limestone Note issued pursuant
to Rule 144A, including any Rule 144A Global Note.

                  "Sale-Leaseback Transaction" means the sale or transfer by the
Guarantor or any Restricted Subsidiary of any Principal Property to a Person
(other than the Guarantor or a Subsidiary) and the taking back by the Guarantor
or any Restricted Subsidiary, as the case may be, of a lease of such Principal
Property.

                  "Shortfall Notice" has the meaning assigned to such term in
Section 5.03.

                  "Special Redemption" has the meaning assigned to such term in
Section 15.04(b).

                  "Special Redemption Date" has the meaning assigned to such
term in Section 15.04(b).

                  "Take-Out Deposit" has the meaning assigned to such term in
Section 15.01(c).

                  "Transfer Restriction Legend" has the meaning assigned to such
term in Section 2.06(d)(i).

                  "Treasury Yield" means, with respect to any Optional
Redemption Date or any Acceleration Date which is attributable to an Event of
Default described in Section 9.01(a), the rate per annum equal to the
semi-annual equivalent yield to maturity of the Comparable Treasury Issue,
assuming

                                       7
<PAGE>

a price for the Comparable Treasury Issue (expressed as a percentage of its
principal amount) equal to the applicable Comparable Treasury Price for such
redemption date.

                  "U.S. Person" means a "U.S. person" within the meaning of
Regulation S.

                  "U.S. Treasuries" means direct general obligations of, or
obligations fully and unconditionally guaranteed as to the timely payment of
principal and interest by, the United States, but excluding any of such
securities whose terms do not provide for payment of a fixed dollar amount upon
maturity or call for redemption.

                  SECTION 1.02. Rules of Construction. This New Indenture and
the definitions referred to in Section 1.01 shall be governed by, and construed
in accordance with, the rules of construction set forth in Section 1.02 of Annex
A to the Participation Agreement.

                  SECTION 1.03. Legal Holidays. In any case where any Limestone
Note Payment Date or any date for the making of a deposit or payment hereunder
shall fall on a day which is not a Business Day, such deposit or payment need
not be made on such date, but may be made on the next succeeding day that is a
Business Day with the same force and effect as if made on such Limestone Note
Payment Date; provided that no interest shall accrue on the amount so payable
for such period.

                  SECTION 1.04. Compliance Certificates and Opinions. Except as
otherwise expressly provided in this New Indenture, upon any application or
request by the Issuers to the New Indenture Trustee that the New Indenture
Trustee take any action under any provision of this New Indenture, the Issuers
shall furnish to the New Indenture Trustee an Issuers' Certificate stating that
all conditions precedent, if any, provided for in this New Indenture relating to
the proposed action have been complied with and an Opinion of Counsel stating
that in the opinion of such counsel all such conditions precedent, if any, have
been complied with, except that in the case of any particular application or
request as to which the furnishing of documents is specifically required by any
provision of this New Indenture relating to such particular application or
request, no additional certificate or opinion need be furnished.

                  Every certificate or opinion with respect to compliance with a
condition or covenant provided for in this New Indenture shall include:

                  (a) a statement that each party providing such certificate or
         opinion has read such covenant or condition;

                  (b) a brief statement as to the nature and scope of the
         examination or investigation upon which the statements or opinions
         contained in such certificate or opinion are based;

                  (c) a statement that, in the opinion of each such party, such
         examination or investigation has been made as is necessary to enable
         such individual to express an informed opinion as to whether or not
         such covenant or condition has been complied with;

                  (d) a statement as to whether, in the opinion of each such
         individual, such condition or covenant has been complied with; and

                  (e) in the case of an Issuers' Certificate, a statement that
         no Indenture Default or Event of Default under this New Indenture has
         occurred and is continuing (unless such Issuers' Certificate relates to
         an Indenture Default or Event of Default).

                  SECTION 1.05. Form of Documents Delivered to Trustee. In any
case where several matters are required to be certified by, or covered by an
opinion of, any specified Person, it is not necessary that all such matters be
certified by, or covered by the opinion of, only one such Person, or that they
be so certified by only one document, but one such Person may certify or give an
opinion with

                                       8
<PAGE>

respect to some matters and one or more other such Persons as to other matters,
and any such Person may certify or give an opinion as to such matters in one or
several documents.

                  Any Issuers' Certificate or Opinion of Counsel of the Issuers
may be based, insofar as it relates to legal matters, upon a certificate or
opinion of, or representations by, counsel, unless the person signing such
Issuers' Certificate or Opinion of Counsel has actual knowledge that the
certificate or opinion or representations with respect to the matters upon which
such Issuers' Certificate or Opinion of Counsel is based are erroneous. Any such
Opinion of Counsel may be based, insofar as it relates to factual matters, upon
an Authorized Officer of the Issuers, El Paso or any other party to the
Transaction Documents, as applicable, stating that the information with respect
to such factual matters is in the possession of such Person unless such counsel
knows that the certificate or opinion or representations with respect to such
matters are erroneous.

                  Any Opinion of Counsel stated to be based on the opinion of
other counsel shall be accompanied by a copy of such other opinion.

                  Where any Person is required to make, give or execute two or
more applications, requests, consents, certificates, statements, opinions or
other instruments under this New Indenture, they may, but need not, be
consolidated and form one instrument.

                                   ARTICLE II

                               THE LIMESTONE NOTES

                  SECTION 2.01. Forms Generally.

                  (a) The New Limestone Notes and the New Indenture Trustee's
Certificate of Authentication shall be in substantially the forms set forth in
Exhibit A hereto (i) in the case of Global Notes, including the Global Note
Legend thereon and the "Schedule of Exchanges of Interests in the Global Note"
attached thereto and (ii) in the case of Definitive Notes, without the Global
Note Legend thereon and without the "Schedule of Exchanges and Interests in the
Global Note" attached, with such appropriate insertions, omissions,
substitutions and other variations as are required or permitted by this New
Indenture, and may have such letters, numbers or other marks of identification
and such legends or endorsements placed thereon as may be required to comply
with applicable laws or the rules of any securities exchange or Depositary or as
may, consistently herewith, be determined by the Authorized Officers executing
such New Limestone Notes, as evidenced by their execution of the New Limestone
Notes. Any portion of the text of any New Limestone Note may be set forth on the
reverse thereof, with an appropriate reference thereto on the face of the New
Limestone Note.

                  The terms and provisions contained in the New Limestone Notes
shall constitute, and are hereby expressly made, a part of this New Indenture
and the Issuers, the Guarantor and the New Indenture Trustee, by their execution
and delivery of this New Indenture, expressly agree to such terms and provisions
and to be bound thereby. To the extent any provision of any New Limestone Note
conflicts with the express provisions of this New Indenture, however, the
provisions of this New Indenture shall govern and be controlling.

                  (b) New Limestone Notes offered in exchange for Limestone
Notes (in accordance with the Exchange Offer) in the United States to QIBs who
are also Qualified Purchasers shall be issued on the Effective Date in the form
of the Rule 144A Global Note in fully registered form without interest coupons
and shall represent the beneficial interests of Persons purchasing such New
Limestone Notes. The Rule 144A Global Note shall be deposited with the New
Indenture Trustee, as custodian (the "Custodian") for the Depositary, duly
executed by the Issuers, endorsed by the Guarantor and

                                       9
<PAGE>

authenticated by the New Indenture Trustee as hereinafter provided. The Rule
144A Global Note may be represented by more than one certificate, if so required
by the Depositary's rule regarding the maximum principal amount to be
represented by a single certificate. The aggregate principal amount of the Rule
144A Global Note may from time to time be increased or decreased by adjustments
made on the records of the Custodian as hereinafter provided. Interests in the
Rule 144A Global Note shall be transferred on the Depositary's book-entry
settlement system in accordance with the Applicable Procedures.

                  (c) Reserved.

                  (d) Reserved.

                  (e) The Issuers, in issuing the New Limestone Notes, may use
"CUSIP" and "ISIN" numbers and if so, the New Indenture Trustee will indicate
the CUSIP and ISIN numbers of the New Limestone Notes in notices of redemption
and related materials as a convenience to New Holders; provided that any such
notice may state that no representation is made as to the correctness of such
numbers either as printed on the New Limestone Notes or as contained in any
notice of redemption and related materials.

                  SECTION 2.02. Authorized Amount; Interest Rate; Maturity Date;
Denominations.

                  (a) The aggregate principal amount of New Limestone Notes
which may be issued and outstanding at any one time under this New Indenture may
not exceed $1,000,000,000, excluding New Limestone Notes issued upon
registration of transfer of, or in exchange for, or in lieu of, other New
Limestone Notes pursuant to Section 2.06 or Section 2.07.

                  (b) The New Limestone Notes shall bear interest at the
Limestone Note Rate. Interest shall accrue on the unpaid principal amount of the
New Limestone Notes from time to time from the last interest payment date on
which interest was paid on the Limestone Notes surrendered in exchange therefor
or, if no such interest has been paid on such Limestone Notes, from the date of
original issuance of such Limestone Notes, and accrued and unpaid interest will
be payable semi-annually in arrears on each Limestone Note Payment Date
commencing September 15, 2002. To the extent permitted by Applicable Law, any
payments due and not punctually paid shall bear interest until paid at the
Limestone Note Rate plus the Default Interest Rate. Interest on the New
Limestone Notes will be computed on the basis of the number of days actually
elapsed (calculated on the basis of a 360-day year consisting of twelve 30-day
months).

                  (c) The maturity date for the New Limestone Notes will be
March 15, 2003 (the "Maturity Date").

                  (d) The New Limestone Notes shall be issuable in minimum
denominations of $100,000 and integral multiples of $1,000 in excess thereof.

                  (e) The New Limestone Notes shall be redeemable as provided in
Section 2.06(f)(x), Article XIV and Article XV.

                  SECTION 2.03. Execution, Authentication, Delivery and Dating.

                  (a) The New Limestone Notes shall be executed on behalf of the
Issuers by an Authorized Officer of each of the Issuers. The signatures of such
Authorized Officers on the New Limestone Notes may be manual or facsimile
(including in counterparts). Each execution of a New Limestone Note by the
Issuers shall be accompanied by the execution of an El Paso Guarantee endorsed
thereon as hereinafter provided in Section 3.05.

                                       10
<PAGE>

                  (b) New Limestone Notes bearing the manual or facsimile
signatures of individuals who were at any time the Authorized Officers of the
Issuers shall bind such Persons, notwithstanding the fact that such individuals
or any of them have ceased to hold such offices prior to the authentication and
delivery of such New Limestone Notes or did not hold such offices at the date of
issuance of such New Limestone Notes. With the delivery of this New Indenture,
the Issuers are furnishing, and from time to time thereafter may furnish, an
Officer's Certificate identifying and certifying the incumbency and specimen
signatures of the Authorized Officers. Until the New Indenture Trustee receives
a subsequent Officer's Certificate, the New Indenture Trustee shall be entitled
to rely on the last such Officer's Certificate delivered to it for purposes of
determining the Authorized Officers. Typographical and other minor errors or
defects in any signature shall not affect the validity or enforceability of any
New Limestone Note which has been duly authenticated and delivered by the New
Indenture Trustee.

                  (c) At any time and from time to time after the execution and
delivery of this New Indenture, the Issuers may deliver the New Limestone Notes
executed by the Issuers and endorsed by the Guarantor to the New Indenture
Trustee for authentication, and the New Indenture Trustee, upon receiving an
Authentication Order, shall authenticate and deliver such New Limestone Notes as
provided in this New Indenture and not otherwise.

                  The New Indenture Trustee may appoint an authenticating agent
acceptable to the Issuers to authenticate the New Limestone Notes. Unless
limited by the terms of such appointment, an authenticating agent may
authenticate New Limestone Notes whenever the New Indenture Trustee may do so.
Each reference in this New Indenture to authentication by the New Indenture
Trustee includes authentication by such agent. An authenticating agent shall
have the same rights as the Registrar and the Paying Agent to deal with New
Holders or any Affiliate of the Issuers.

                  (d) Each New Limestone Note authenticated and delivered by the
New Indenture Trustee upon Authentication Order on the Effective Date shall be
dated as of the Effective Date. All other New Limestone Notes that are
authenticated after the Effective Date for any other purpose under this New
Indenture shall be dated the date of their authentication. The New Limestone
Notes issued as of the Effective Date and any other New Limestone Notes
subsequently issued under this New Indenture shall be treated as a single class
for all purposes under this New Indenture, including, without limitation,
payments, waivers, amendments, redemptions and offers to purchase.

                  (e) New Limestone Notes issued upon transfer, exchange or
replacement of other New Limestone Notes shall be issued in authorized
denominations reflecting the original aggregate principal amount of the New
Limestone Notes so transferred, exchanged or replaced.

                  (f) No New Limestone Note shall be entitled to any benefit
under this New Indenture or be valid or obligatory for any purpose, unless there
appears on such New Limestone Note a certificate of authentication (the
"Certificate of Authentication") substantially in the form provided for herein,
executed by the New Indenture Trustee by the manual signature of one of its
Authorized Officers, and such certificate upon any New Limestone Note shall be
conclusive evidence, and the only evidence, that such New Limestone Note has
been duly authenticated and delivered hereunder.

                  SECTION 2.04. Registrar and Paying Agent; Registration.

                  (a) The Issuers shall cause to be kept at the Corporate Trust
Office one or more books (the "Note Register") for the registration of the New
Limestone Notes and the registration of transfer or exchange of any of the New
Limestone Notes. The Note Register shall be in written form or any other form
capable of being converted into written form within a reasonable time. At all
reasonable times, the Note Register shall be open to inspection by the New
Indenture Trustee. The New Indenture Trustee is hereby initially appointed as
security registrar (the "Registrar") for the purpose of registering New
Limestone Notes and transfers of New Limestone Notes as hereinafter provided.

                                       11
<PAGE>

                  (b) The Issuers shall maintain an office or agency with a
Person in the Borough of Manhattan in The City of New York where New Limestone
Notes may be presented for payment and The Bank of New York is hereby initially
appointed as Paying Agent for the New Limestone Notes. The Issuers shall give
prompt written notice to the New Indenture Trustee and the New Indenture Trustee
shall notify the Rating Agencies and the New Noteholders of the appointment or
termination of any Paying Agent or agent for notices and of the location and any
change in the location of any such office or agency.

                  (c) The Issuers shall require each Paying Agent other than The
Bank of New York to agree in writing, and The Bank of New York, in its capacity
as the initial Paying Agent hereby agrees, that the Paying Agent will hold in
trust for the benefit of New Holders and the New Indenture Trustee all money
held by the Paying Agent for the payment of principal, premium, if any, or
interest on the New Limestone Notes, and will notify the New Indenture Trustee
in writing of any default by the Issuers in making any such payment. While any
such default continues, the New Indenture Trustee may require the Paying Agent
to pay all money held by it to the New Indenture Trustee. The Issuers, at any
time, may require the Paying Agent to pay all money held by it to the New
Indenture Trustee. Upon payment over to the New Indenture Trustee, the Paying
Agent (if other than the Issuers) shall have no further liability for the money.
If the Issuers act as Paying Agents, they shall segregate and hold in a separate
trust fund for the benefit of the New Holders all money held by them as Paying
Agents. Upon any bankruptcy or reorganization proceedings relating to the
Issuers, if the Issuers are then acting as Paying Agents, the New Indenture
Trustee shall thereafter serve as Paying Agent for the New Limestone Notes, and
the Issuers shall immediately pay or cause to be paid to the New Indenture
Trustee all money held by them in their respective capacities as Paying Agents.

                  SECTION 2.05. Payments of Principal and Interest; Rights
Preserved.

                  (a) Notwithstanding any provision of this New Indenture or the
New Limestone Notes to the contrary other than Sections 14.02(f), 15.02(e) and
15.05(f), payments of all amounts which become due and payable in respect of any
New Limestone Note other than payment in full shall be made by the Paying Agent
directly to the New Holder of such New Limestone Note, without surrender or
presentation thereof to the Paying Agent.

                  (b) The Issuers hereby covenant with the Paying Agent to pay
or cause to be paid to the Paying Agent, prior to 3:00 p.m., New York City time,
on each Limestone Note Payment Date, all amounts from time to time due and
payable by them hereunder and under the New Limestone Notes to any New
Noteholder as herein and therein provided (including the manner of payment
thereof).

                  (c) The unpaid principal balance of each New Limestone Note
shall be payable on the Maturity Date thereof unless the principal of such New
Limestone Note becomes due and payable at an earlier date by declaration of
acceleration, call for redemption or otherwise. Except as provided in Section
14.03 or Section 15.06, any repayment of principal shall be applied ratably to
repay the New Limestone Notes Outstanding. The final installment of principal on
any New Limestone Note, whether at maturity or upon redemption, will be payable
only upon surrender of such New Limestone Note at the Corporate Trust Office or
at the specified offices of any Paying Agent and will be made to the Person
surrendering such New Limestone Note.

                  If the due date for payment of the final installment of
principal in respect of any New Limestone Note is not a Business Day at the
place in which it is presented for payment, the New Noteholder thereof will not
be entitled to payment of the amount due until the next succeeding Business Day
at such place and will not be entitled to any further interest or other payment
in respect of any such delay.

                  (d) Interest on any New Limestone Note which is payable, and
is punctually paid or duly provided for by the Issuers on any Limestone Note
Payment Date, shall be paid to the Person in

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<PAGE>

whose name that New Limestone Note is registered at the close of business on the
Record Date for such interest.

                  (e) All reductions in the principal amount of a New Limestone
Note (or one or more predecessor New Limestone Notes) effected by payments of
principal made on any Optional Redemption Date or Special Redemption Date, as
applicable, shall be binding upon all future New Holders of such New Limestone
Notes and of any New Limestone Note issued upon the registration of transfer
thereof or in exchange therefor or in lieu thereof, whether or not such payment
is noted on such New Limestone Note.

                  (f) (i) Notwithstanding any other term of this New Indenture,
the New Limestone Notes, any other Transaction Document or otherwise, the
obligations of the Issuers under the New Limestone Notes and this New Indenture
are senior unsecured limited recourse obligations of the Issuers, payable solely
from the following (the "Recourse for the Notes"):

                  (A) all of the rights of Limestone, excluding Excepted Rights,
under the Participation Agreement, the Security Agreement, the Chaparral LLC
Agreement and the other Transaction Documents (other than the Note Purchase
Agreement, the Dealer Manager Agreement, the Limestone Notes, the New Limestone
Notes, the Limestone Certificates, the Remarketing Agreement and the Share Trust
Agreement) to which it is a party;

                  (B) all of the rights of Limestone under the Class A Member
Interest and any Additional Class B Member Interest;

                  (C) all of the rights of Limestone against the Overfund Trust
and the El Paso Debt Securities or other Financial Investments purchased with
the Overfund Amount and held by the Overfund Trust;

                  (D) each of the Indenture Accounts and the New Notes Account,
all amounts credited to such Indenture Accounts and the New Notes Account
pursuant to the applicable provisions of the Indenture and this New Indenture
and all investments of such amounts pursuant to the applicable provisions of the
Indenture and this New Indenture, including all securities, financial assets and
securities entitlements carried in such Indenture Accounts and the New Notes
Account; and

                  (E) all proceeds of the conversion, voluntary or involuntary,
of any of the foregoing into cash, instruments, securities or other property,
including without limitation all amounts from time to time held in or credited
to the Indenture Accounts and the New Notes Account, whether in the form of cash
or invested in instruments, securities or other property, including all property
hereafter required to be subject to the Lien of the Indenture by any instrument
supplemental thereto.

Following realization of the Recourse for the Notes and application of proceeds
thereof in accordance with the terms of the Indenture, this New Indenture and
Section 6.04(b) of the Limestone Trust Agreement, none of the New Noteholders
nor the New Indenture Trustee shall be entitled to take any further action
against the Issuers to recover any sums due but remaining unpaid hereunder or
thereunder, all claims in respect of which shall be extinguished. In particular,
neither the New Indenture Trustee nor any New Noteholder shall be entitled to
petition or take any other action for the winding up or bankruptcy of either of
the Issuers or shall have any claim in respect of any assets of the Issuers
other than the Recourse for the Notes. No recourse shall be had for the payment
of any amount owing in respect of the New Limestone Notes against any trustee,
officer, director, employee, shareholder, Certificateholder or incorporator of
the Issuers, the New Holders of the New Limestone Notes, the holders of the
Limestone Notes, the New Indenture Trustee, the Indenture Trustee, the Dealer
Manager, their respective Affiliates or any of their successors or assigns for
any amounts payable under the New Limestone Notes or this New Indenture. It is
understood that the foregoing provisions of this paragraph (f) shall not prevent

                                       13
<PAGE>

recourse to (i) the Recourse for the Notes for the sums due or to become due
under any security, instrument or agreement which is part of the Recourse for
the Notes, (ii) except as specifically provided therein, constitute a waiver,
release or discharge of any indebtedness or obligation evidenced by the New
Limestone Notes or guaranteed by this New Indenture or (iii) prevent any action
to recover any sums due but remaining unpaid hereunder or under the New
Limestone Notes from the Guarantor in respect of its payment obligations under
the El Paso Guarantee. It is further understood that the foregoing provisions of
this paragraph (f) shall not limit the right of any Person to name the Issuers
as party defendants in any Proceeding or in the exercise of any other remedy
under the New Limestone Notes or this New Indenture, so long as no judgment in
the nature of a deficiency judgment or seeking personal liability shall be asked
for or (if obtained) enforced against any such Person.

                  (ii) Notwithstanding the foregoing clause (i), upon (A) the
occurrence of an Event of Default and (B) the acceleration of the New Limestone
Notes as a result thereof, the New Indenture Trustee may not take any action
against the Recourse for the Notes until the expiration of 120 days following
the acceleration of the New Limestone Notes; provided that the New Indenture
Trustee may take action against the Recourse for the Notes only after a judgment
has been rendered against the Issuers in connection with an enforcement
proceeding brought to remedy a failure by the Issuers to perform their
obligations under this New Indenture.

                  (iii) In pursuing any remedy against the Recourse for the
Notes in connection with an enforcement proceeding brought to remedy a failure
by the Issuers to perform their obligations under this New Indenture, each of
the New Indenture Trustee and, by its acceptance of its New Limestone Note, each
New Noteholder, acknowledges and agrees that any sale of the Class A Member
Interest or the Mesquite LLC Interest made within 300 days following the
acceleration of the New Limestone Notes may be made only to the extent the sales
price therefor is at least equal to an amount sufficient to repay the Limestone
Notes and the New Limestone Notes in full plus all of the Certificateholders'
investment and accrued and unpaid yield; provided that to the extent the sales
price therefor is at least equal to an amount sufficient to repay the Limestone
Notes in full, the Certificateholders shall have the right to waive the
limitation set forth in this Section 2.05(f)(iii) by written notice to the New
Indenture Trustee.

                  (iv) In connection with an Asset Disposition after Limestone
exercises its rights pursuant to Section 6.1(a) of the Chaparral LLC Agreement
as a result of the occurrence of a Specified Equity Event, Limestone
acknowledges and agrees, on behalf of itself and any designee, that any sale of
the Class A Member Interest or Mesquite LLC Interest made within 300 days after
the occurrence of the applicable Specified Equity Event may be made only to the
extent the sales price therefor is at least equal to an amount sufficient to
repay the Limestone Notes and the New Limestone Notes in full plus all of the
Certificateholders' investment and accrued and unpaid yield; provided that to
the extent the sales price therefor is at least equal to an amount sufficient to
repay the Limestone Notes in full, each of the New Indenture Trustee and, by its
acceptance of its New Limestone Note, each New Noteholder, acknowledges and
agrees that the Certificateholders shall have the right to waive the limitation
set forth in this Section 2.05(f)(iv) by written notice to the New Indenture
Trustee.

                  (v) Notwithstanding any other provision in this New Indenture
or any action by the New Indenture Trustee upon the rights of Limestone under
the Chaparral LLC Agreement or the Security Agreement and the El Paso Debt
Securities purchased with the Overfund Amount or the Financial Investments
purchased with the proceeds thereof, each of the New Indenture Trustee and, by
its acceptance of its New Limestone Note, each New Noteholder, acknowledges and
agrees that the Certificateholders will be entitled to receive payments of
accrued and unpaid Limestone Certificate Yield and accrued and unpaid Default
Yield pursuant to Section 5.04(a) of the Indenture or, after the satisfaction
and discharge of the Indenture, Section 6.03(a) of the Limestone Trust
Agreement, from the proceeds of the El Paso Debt Securities or the Financial
Investments purchased with the Overfund Amount, or the proceeds of the Financial
Investments purchased with the proceeds of the El Paso Debt Securities if the El
Paso Debt Securities are repaid by El Paso pursuant to Section 5.5(a) of the

                                       14
<PAGE>

Participation Agreement and are reinvested in Financial Investments, until such
time as the Class A Member Interest is sold.

                  (g) Notwithstanding any other term of this New Indenture, the
New Limestone Notes or any other Transaction Document or otherwise, neither of
the Issuers shall have any liability whatsoever to each other under this New
Indenture, the New Limestone Notes or any other Transaction Document or
otherwise and, without prejudice to the generality of the foregoing, neither of
the Issuers shall be entitled to take any action to enforce, or bring any
Proceeding, in respect of this New Indenture, the New Limestone Notes or any
other Transaction Document or otherwise against each other. In particular,
neither of the Issuers shall be entitled to petition or take any other steps for
the winding up or bankruptcy of the other or shall have any claim in respect of
any assets of the other (other than a claim by Limestone as a shareholder of the
Co-Issuer).

                  (h) Subject to the foregoing provisions of this Section 2.05,
each New Limestone Note delivered under this New Indenture upon registration of
transfer of or in exchange for or in lieu of any other New Limestone Note shall
carry the rights of unpaid interest and principal that were carried by such
other New Limestone Note.

                  (i) Notwithstanding any of the foregoing provisions with
respect to payments of principal of and interest on the New Limestone Notes, if
the New Limestone Notes have become or been declared due and payable or subject
to redemption following an Event of Default or a Specified Equity Event and such
acceleration of maturity or redemption and its consequences have not been
rescinded and annulled, then payments of principal of and interest on such New
Limestone Notes shall be made in accordance with Section 5.04.

                  SECTION 2.06. Transfer and Exchange of New Limestone Notes.

                  (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
will be exchanged by the Issuers for Definitive Notes if (i) the Issuers deliver
to the New Indenture 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 120 days after the date of
such notice from the Depositary or (ii) the Issuers in their sole discretion
determine that the Global Notes (in whole but not in part) should be exchanged
for Definitive Notes and deliver a written notice to such effect to the New
Indenture Trustee. Upon the occurrence of either of the preceding events in
clause (i) or clause (ii) above, Definitive Notes shall be issued in such names
as the Depositary shall instruct the New Indenture Trustee. Global Notes also
may be exchanged or replaced, in whole or in part, as provided in Section 2.07.
Every New Limestone Note authenticated and delivered in exchange for, or in lieu
of, any Global Note or any portion thereof, pursuant to this Section 2.06 or
Section 2.07, shall be authenticated and delivered in the form of, and shall be,
a Global Note. A Global Note may not be exchanged for another New Limestone 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).

                  (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 New 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 and the Investment Company 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:

                                       15
<PAGE>

                           (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 Transfer Restriction
         Legend. 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).

                           (ii) All Other Transfers and Exchanges of Beneficial
         Interests in Global Notes. In connection with all transfers and
         exchanges of beneficial interests that are not subject to Section
         2.06(b)(i) above, the transferor of such beneficial interest must
         deliver to the Registrar either (A)(1) 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 (2) instructions given in accordance with the Applicable
         Procedures containing information regarding the Participant account to
         be credited with such increase. Upon satisfaction of all of the
         requirements for transfer or exchange of beneficial interests in Global
         Notes contained in this New Indenture and the New Limestone Notes or
         otherwise applicable under the Securities Act, the New Indenture
         Trustee shall adjust the principal amount of the relevant Global
         Note(s) pursuant to Section 2.06(e).

                           (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 Section 2.06(b)(ii) above
         and the Registrar receives the following:

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

                                    (B) Reserved.

                                    (C) Reserved.

                  (c) Transfer and Exchange of Definitive Notes for Definitive
Notes.

                           (i) Following the issuance of Definitive Notes in
       exchange for the Global Notes pursuant to Section 2.06(a), upon request
       by a New Holder of Definitive Notes and such New Holder's compliance with
       the provisions of this Section 2.06(c), the Registrar shall register the
       transfer or exchange of Definitive Notes. Prior to such registration of
       transfer or exchange, the requesting New Holder shall present or
       surrender to the Registrar the Definitive Notes duly endorsed or
       accompanied by a written instruction of transfer in form satisfactory to
       the Registrar duly executed by such New Holder or by his attorney, duly
       authorized in writing. In addition, the requesting New Holder shall
       provide any additional certifications, documents and information, as
       applicable, required pursuant to the following provisions of this Section
       2.06(c).

                           (ii) Restricted Definitive Notes to Restricted
         Definitive Notes. Any Restricted Definitive Note may be transferred to
         and registered in the name of Persons who take delivery thereof in the
         form of a Restricted Definitive Note 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 C hereto,
                  including the certifications in item (1) thereof; or

                                       16
<PAGE>

                                    (B) Reserved.

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

                           (i) Transfer Restriction Legend. Each Global Note and
         each Definitive Note (and all New Limestone Notes issued in exchange
         therefor or substitution thereof) shall bear the legend (the "Transfer
         Restriction Legend") in substantially the following form:

         "THE SECURITIES EVIDENCED HEREBY HAVE NOT BEEN REGISTERED UNDER THE
         UNITED STATES SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES
         ACT"), OR ANY STATE OR OTHER SECURITIES LAWS AND THE ISSUERS HAVE NOT
         BEEN REGISTERED UNDER THE INVESTMENT COMPANY ACT OF 1940, AS AMENDED
         (THE "INVESTMENT COMPANY ACT"). ACCORDINGLY, NEITHER THIS SECURITY NOR
         ANY INTEREST OR PARTICIPATION HEREIN MAY BE REOFFERED, SOLD, ASSIGNED,
         TRANSFERRED, PLEDGED, ENCUMBERED OR OTHERWISE DISPOSED OF WITHIN THE
         UNITED STATES OR TO, OR FOR THE ACCOUNT OR BENEFIT OF, U.S. PERSONS,
         EXCEPT IN ACCORDANCE WITH APPLICABLE SECURITIES LAWS OF ANY STATE OF
         THE UNITED STATES AND SECTION 3(c)(7) OF THE INVESTMENT COMPANY ACT. BY
         ITS ACQUISITION HEREOF OR OF A BENEFICIAL INTEREST HEREIN, THE NEW
         HOLDER: (1) REPRESENTS THAT IT IS A "QUALIFIED INSTITUTIONAL BUYER" (AS
         DEFINED IN RULE 144A UNDER THE SECURITIES ACT) (A "QIB"); (2)
         REPRESENTS THAT IT IS A "QUALIFIED PURCHASER" (AS DEFINED IN SECTION
         2(a) OF THE INVESTMENT COMPANY ACT) (A "QP"); (3) REPRESENTS THAT IT IS
         NOT (A) A DEALER DESCRIBED IN RULE 144A(a)(1)(ii) THAT OWNS AND INVESTS
         ON A DISCRETIONARY BASIS LESS THAN $25,000,000 IN SECURITIES OF ISSUERS
         THAT ARE NOT AFFILIATED WITH THE DEALER, (B) A PARTNERSHIP, COMMON
         TRUST FUND, SPECIAL TRUST, PENSION FUND, RETIREMENT PLAN OR OTHER
         ENTITY IN WHICH THE PARTNERS, BENEFICIARIES, BENEFICIAL OWNERS OR
         PARTICIPANTS, AS THE CASE MAY BE, MAY DESIGNATE THE PARTICULAR
         INVESTMENTS TO BE MADE OR THE ALLOCATION THEREOF, (C) AN INVESTMENT
         COMPANY EXCEPTED FROM THE INVESTMENT COMPANY ACT PURSUANT TO SECTION
         3(c)(1) OR SECTION 3(c)(7) THEREOF (OR A FOREIGN INVESTMENT COMPANY
         UNDER SECTION 7(d) THEREOF RELYING ON SECTION 3(c)(1) OR SECTION
         3(c)(7) THEREOF WITH RESPECT TO ITS U.S. HOLDERS) AND FORMED ON OR
         PRIOR TO APRIL 30, 1996, THAT HAS NOT RECEIVED THE CONSENT OF EACH OF
         ITS BENEFICIAL OWNERS WITH RESPECT TO ITS TREATMENT AS A QUALIFIED
         PURCHASER IN THE MANNER REQUIRED BY SECTION 2(a)(51)(C) OF THE
         INVESTMENT COMPANY ACT AND THE RULES THEREUNDER OR (D) AN ENTITY THAT
         WILL HAVE INVESTED MORE THAN FORTY PERCENT (40%) OF ITS ASSETS IN THE
         SECURITIES OF THE ISSUERS SUBSEQUENT TO THE PURCHASE OF THE NEW
         LIMESTONE NOTES; (4) REPRESENTS THAT IT WAS NOT FORMED FOR THE PURPOSE
         OF INVESTING IN THE ISSUERS; (5) AGREES THAT IT WILL PROVIDE NOTICE OF
         APPLICABLE TRANSFER RESTRICTIONS TO ANY SUBSEQUENT TRANSFEREE; (6)
         AGREES THAT EACH ACCOUNT FOR WHICH IT IS PURCHASING WILL HOLD AND
         TRANSFER AT LEAST THE MINIMUM DENOMINATIONS OF $100,000 AND $1,000 IN
         EXCESS THEREOF OF NEW LIMESTONE NOTES; (7) REPRESENTS THAT IT IS
         PURCHASING FOR ITS OWN ACCOUNT OR FOR THE ACCOUNTS OF ONE OR MORE OTHER
         PERSONS EACH OF WHOM MEETS ALL OF THE REQUIREMENTS OF CLAUSES (1)
         THROUGH (6); AND (8) AGREES THAT IT WILL NOT OFFER, SELL OR OTHERWISE
         TRANSFER THIS SECURITY EXCEPT TO A PERSON THAT MEETS ALL OF THE
         REQUIREMENTS OF CLAUSES (1) THROUGH (7)

                                       17
<PAGE>

         AND THAT AGREES NOT TO SUBSEQUENTLY TRANSFER THIS NEW LIMESTONE NOTE OR
         ANY INTEREST HEREIN EXCEPT IN ACCORDANCE WITH THIS CLAUSE (8)."

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

         "UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE
         OF THE DEPOSITORY TRUST COMPANY 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 TO SUCH OTHER ENTITY
         AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST
         COMPANY OR SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED
         REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY (AND ANY PAYMENT HEREON
         IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN
         AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY), ANY
         TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
         ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO.,
         HAS AN INTEREST HEREIN.

         TRANSFERS OF THIS GLOBAL NOTE SHALL BE LIMITED TO TRANSFERS IN WHOLE,
         BUT NOT IN PART, TO NOMINEES OF CEDE & CO. OR TO A SUCCESSOR THEREOF OR
         SUCH SUCCESSOR'S NOMINEE AND TRANSFERS OF BENEFICIAL INTERESTS IN THIS
         GLOBAL NOTE SHALL BE LIMITED TO TRANSFERS MADE IN ACCORDANCE WITH THE
         RESTRICTIONS SET FORTH IN SECTION 2.06 OF THE NEW INDENTURE."

                           (iii) Reserved.

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

         "EACH NEW HOLDER OF THIS SECURITY OR ANY INTEREST HEREIN SHALL BE
         DEEMED TO HAVE REPRESENTED WITH RESPECT TO ITSELF AND EACH ACCOUNT FOR
         WHICH IT IS PURCHASING THAT IT AND EACH ACCOUNT SATISFY THE
         REQUIREMENTS SET FORTH IN THE LEGENDS ON THE FACE OF THIS SECURITY AND
         ANY RESALE OR OTHER TRANSFER OF THIS SECURITY OR ANY INTEREST HEREIN
         MAY ONLY BE MADE TO A PERSON SATISFYING THE REQUIREMENTS HEREIN AND IN
         THE NEW INDENTURE. IF AT ANY TIME THE ISSUERS DETERMINE THAT A NEW
         HOLDER OF THE SECURITY OR ANY INTEREST HEREIN WAS IN BREACH, AT THE
         TIME GIVEN, OF ANY OF THE REPRESENTATIONS OR AGREEMENTS SET FORTH
         HEREIN OR IN THE NEW INDENTURE, THE ISSUERS MAY CONSIDER THE
         ACQUISITION OF THIS SECURITY OR SUCH INTEREST HEREIN NULL AND VOID, AND
         THE ISSUERS MAY REQUIRE THAT THE NEW LIMESTONE NOTES BE TRANSFERRED TO
         A PERSON THAT MEETS THE REQUIREMENTS THEREOF OR REDEEMED AT PAR BY THE
         ISSUERS."

                  (e) Cancellation and/or Adjustment of Global Notes. At such
time as all beneficial interest in a particular Global Note have been exchanged
for Definitive 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 New Indenture Trustee in accordance with Section
2.09. 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
Definitive Notes, the principal amount of New Limestone Notes represented by
such Global Note

                                       18
<PAGE>
shall be reduced accordingly and an endorsement shall be made on such Global
Note by the New Indenture Trustee or by the Depositary at the direction of the
New Indenture 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 New Indenture Trustee or by the Depositary at the direction
of the New Indenture Trustee to reflect such increase.

                  (f) General Provisions Relating to Transfers and Exchanges.

                           (i) To permit registrations of transfers and
         exchanges, the Issuers shall execute, the Guarantor shall endorse and
         the New Indenture Trustee shall authenticate Global Notes and
         Definitive Notes upon the Issuers' order or at the Registrar's request.

                           (ii) No service charge shall be made to a owner of a
         beneficial interest in a Global Note or to a New Holder of a Definitive
         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.

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

                           (iv) All Global Notes and Definitive Notes issued
         upon any registration of transfer or exchange of Global Notes or
         Definitive Notes shall be the valid obligations of the Issuers and the
         Guarantor, evidencing the same debt, and entitled to the same benefits
         under this New Indenture, as the Global Notes or Definitive 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 any New Limestone Notes
         during a period beginning at the opening of business 15 days before the
         day of any selection of New Limestone Notes for redemption under
         Section 14.03 or Section 15.06 and ending at the close of business on
         the day of selection, (B) to register the transfer of or to exchange
         any New Limestone Note so selected for redemption in whole or in part,
         except the unredeemed portion of any New Limestone Note being redeemed
         in part or (C) to register the transfer of or to exchange a New
         Limestone Note between a Record Date and the next succeeding Limestone
         Note Payment Date.

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

                           (vii) The New Indenture Trustee shall authenticate
         Global Notes and Definitive Notes in accordance with the provisions of
         Section 2.03.

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

                           (ix) The Issuers shall not be required to honor any
         transfer or exchange of any New Limestone Notes to transferees who are
         not Qualified Purchasers.

                                       19
<PAGE>

                           (x) The Issuers shall have the right to (i) cause any
         owner of a beneficial interest in a Global Note who is not a Qualified
         Purchaser to sell such beneficial interest to a Qualified Purchaser,
         (ii) cause any holder of a Definitive Note who is not a Qualified
         Purchaser to sell such Definitive Note to a Qualified Purchaser, (iii)
         redeem the beneficial interest of a holder of a Global Note who is not
         a Qualified Purchaser at a price equal to the sum of the accrued and
         unpaid interest to the date of redemption and 100% of the outstanding
         principal amount of such New Limestone Note and (iv) redeem the
         Definitive Note of a holder who is not a Qualified Purchaser at a price
         equal to the sum of the accrued and unpaid interest to the date of
         redemption and 100% of the outstanding principal amount of such New
         Limestone Note.

                  SECTION 2.07. Replacement of Lost, Mutilated or Stolen New
Limestone Notes. In case any New Limestone Note shall become mutilated or
defaced or be lost, destroyed or stolen, then on the terms herein set forth, and
not otherwise, the Issuers shall execute, the Guarantor shall endorse and the
New Indenture Trustee shall authenticate and deliver to the registered New
Holder a new New Limestone Note of like tenor and date, and bearing such
identifying number or designation as the New Indenture Trustee may determine, in
exchange and substitution for, and upon cancellation of, the mutilated or
defaced New Limestone Note, or in lieu of and in substitution for the same if
lost, destroyed or stolen. The applicant for a new New Limestone Note pursuant
to this Section 2.07 shall, in the case of any mutilated or defaced New
Limestone Note, surrender such New Limestone Note to the New Indenture Trustee
and furnish to the New Indenture Trustee in the case of any lost, destroyed or
stolen New Limestone Note, evidence satisfactory to the New Indenture Trustee of
such loss, destruction or theft and, in each case, evidence satisfactory to the
New Indenture Trustee of the ownership and authenticity of such New Limestone
Note and shall pay all expenses and charges of such substitution and furnish
such security or indemnity as may be reasonably required by the New Indenture
Trustee, the Issuers and the Guarantor to indemnify and defend and save them
harmless. Any defaced or mutilated New Limestone Note shall be destroyed by the
New Indenture Trustee, or retained in accordance with its standard retention
policy, upon delivery by it of a new New Limestone Note to the New Holder.

                  SECTION 2.08. Taxes.

                  (a) Any and all payments by or on behalf of the Issuers to or
for the account of any New Noteholder or the New Indenture Trustee hereunder,
under any New Limestone Note or under any other Transaction Document shall be
made without set-off or counterclaim and, except as otherwise required by law,
free and clear of and without deduction for any and all Taxes. If any Taxes
shall be required by law to be deducted from or in respect of any sum payable
hereunder, under any New Limestone Note or under any other Transaction Document
to any New Noteholder or the New Indenture Trustee, the New Indenture Trustee
shall make such deduction and shall pay such Taxes directly to the relevant
taxing authority or other authority in accordance with applicable law. Within 30
days after the payment of any Taxes by the New Indenture Trustee, the New
Indenture Trustee shall promptly deliver to the relevant New Noteholder or New
Noteholders such receipts together with the original or a certified copy of any
receipts evidencing payment of any Taxes paid directly by the New Indenture
Trustee. No additional amounts shall be payable by the Issuers or the Guarantor
to any New Noteholder in respect of Taxes required to be deducted or withheld.

                  (b) The New Indenture Trustee shall collect such duly
completed forms or other certifications from each New Noteholder as shall permit
them to receive payments under the New Limestone Notes without withholding or
deduction on account of Taxes and shall promptly forward copies of such forms to
El Paso. In addition, the New Indenture Trustee shall, to the extent it is
legally able to do so, execute and file such forms, and take such other actions
as are reasonably necessary to permit payments under the New Limestone Notes to
be made without withholding or deduction on account of Taxes.

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<PAGE>

                  (c) The New Limestone Notes have been issued with the
intention that such New Limestone Notes will qualify under applicable Federal,
state and local income tax law as indebtedness. Each of the Issuers and each New
Noteholder, by its acceptance of a New Limestone Note, agrees to treat the New
Limestone Notes as indebtedness of Limestone for purposes of Federal, state and
local income or franchise taxes, or for any other tax imposed on or measured by
income and agrees that, to the extent it is required to report any item of
income, gain, loss, deduction or credit relating to the New Limestone Notes for
United States Federal, state or local income tax purposes, it shall report such
item in a manner consistent with the characterization intended by this Section
2.08(c) and shall not take any contrary position on any tax return or report
relating to the United States Federal, state or local income taxes or take any
other action which is inconsistent with such characterization. The Issuers
covenant and agree to exercise at all times such rights, powers, and obligations
they may have through an office located in Delaware or New York.

                  SECTION 2.09. Cancellation. All New Limestone Notes
surrendered for payment, registration of transfer, exchange or redemption, or
deemed lost or stolen pursuant to Section 2.07, shall, if surrendered to any
Person other than the New Indenture Trustee, be delivered to the New Indenture
Trustee and shall be promptly canceled by it. All canceled New Limestone Notes
held by the New Indenture Trustee shall be destroyed or held by the New
Indenture Trustee in accordance with its standard retention policy.

                                   ARTICLE III

                        GUARANTEE OF NEW LIMESTONE NOTES

                  SECTION 3.01. El Paso Guarantee. Subject to the provisions of
this Article III, the Guarantor hereby, fully, unconditionally and irrevocably
guarantees to each New Noteholder and to the New Indenture Trustee on behalf of
the New Noteholders the due and punctual payment of the principal of, and
premium, if any, and interest on, each New Limestone Note, when and as the same
shall become due and payable, whether at maturity, by acceleration or otherwise,
and the due and punctual payment of the Default Interest, if any, on the New
Limestone Notes, all in accordance with the terms of such New Limestone Note and
this New Indenture (such obligations being herein collectively referred to as
the "Guaranteed Obligations"). The Guarantor hereby waives diligence,
presentment, demand of payment, filing of claims with a court in the event of
merger or bankruptcy of the Issuers, any right to require a proceeding first
against the Issuers, the benefit of protest or notice with respect to any such
New Limestone Note or the debt evidenced thereby and all demands whatsoever
(except as specified herein), and covenants that the El Paso Guarantee will not
be discharged as to any such New Limestone Note except by payment in full of the
principal thereof and interest (including any accrued and unpaid Default
Interest) and premium (if any) thereon as provided in Section 5.04. In the event
of any declaration of acceleration of the principal of and interest on the New
Limestone Notes as provided in Section 9.01, such obligations shall forthwith
become due and payable by the Guarantor for the purpose of this Article III. In
addition, without limiting the foregoing provisions, upon (a) the effectiveness
of an acceleration of the New Limestone Notes under Section 9.01 or (b) the
occurrence of any other claim by the New Noteholders or the New Indenture
Trustee under the El Paso Guarantee, the New Indenture Trustee shall immediately
make a written demand for payment (which demand shall set forth the amount then
due and payable) under the El Paso Guarantee; provided, that the failure of the
New Indenture Trustee to make such demand for payment will not relieve the
Guarantor from its obligation to make any such payment under the El Paso
Guarantee.

                  If the New Indenture Trustee or the New Holder of any New
Limestone Note is required by any court or otherwise to return to the Issuers or
the Guarantor, or any custodian, receiver, liquidator, trustee, sequestrator or
other similar official acting in relation to the Issuers or the Guarantor, any
amount paid to the New Indenture Trustee or such New Noteholder in respect of a
New Limestone Note, the El Paso Guarantee, to the extent theretofore discharged,
shall be reinstated in full force and effect. The

                                       21
<PAGE>

Guarantor further agrees, to the fullest extent that it may lawfully do so,
that, as between it, on the one hand, and the New Noteholders and the New
Indenture Trustee, on the other hand, the maturity of the Guaranteed Obligations
may be accelerated as provided in Section 9.01 for the purposes of the El Paso
Guarantee, notwithstanding any stay, injunction or other prohibition extant
under any applicable bankruptcy law preventing such acceleration in respect of
the Guaranteed Obligations.

                  The Guarantor hereby agrees that until (x) the payment or
satisfaction in full of the Guaranteed Obligations (whether by payment,
redemption or otherwise) and (y) the cancellation of the outstanding Limestone
Certificates in accordance with Section 7.04 of the Limestone Trust Agreement or
the receipt by the Certificateholders of the EP Purchase Option Deposit Amount
in accordance with Section 7.02 of the Limestone Trust Agreement, it shall not
exercise any right or remedy against the Issuers by reason of the existence,
payment, performance or enforcement of its obligations under the El Paso
Guarantee and this New Indenture, including, without limitation, any right of
subrogation, reimbursement, exoneration, contribution, indemnification, any
right to participate in any claim or remedy of the New Noteholders against the
Issuers or any collateral which any such New Noteholder or the New Indenture
Trustee on behalf of such New Noteholder hereafter acquires, whether or not such
claim, remedy or right arises in equity or under contract, statute or common
law, including, without limitation, the right to take or receive from the
Issuers, directly or indirectly, in cash or other property or by set-off or in
any other manner, payment or security on account of such claim or other rights.
If any amount shall be paid to the Guarantor in violation of the preceding
sentence and the principal of, and premium, if any, and accrued interest
(including any accrued and unpaid Default Interest) on, the New Limestone Notes
shall not have been paid in full, such amount shall be deemed to have been paid
to the Guarantor for the benefit of, and held in trust for the benefit of, the
New Noteholders, and shall forthwith be paid to the New Indenture Trustee for
the benefit of the New Noteholders to be credited and applied upon the principal
of, and premium, if any, and accrued interest (including any accrued and unpaid
Default Interest) on, the New Limestone Notes. The Guarantor acknowledges that
it will receive direct and indirect benefits from the issuance of the New
Limestone Notes pursuant to this New Indenture and that the agreements set forth
in this Section 3.01 are knowingly made in contemplation of such benefits.

                  The El Paso Guarantee set forth in this Section 3.01 shall not
be valid or become obligatory for any purpose with respect to a New Limestone
Note until such New Limestone Note shall have been authenticated by the New
Indenture Trustee. Each New Noteholder, by its acceptance of a New Limestone
Note, agrees that it will not waive its remedies with respect to this Article
III or the El Paso Guarantee, including, without limitation, releasing the
Guarantor from any of its obligations under the El Paso Guarantee or reducing
the amount of such Guaranteed Obligations, without the consent of Limestone.

                  SECTION 3.02. Obligations Unconditional. Nothing contained in
this Article III or elsewhere in this New Indenture or in the New Limestone
Notes is intended to or shall impair, as among the Guarantor and the New
Noteholders, the obligations of the Guarantor, which are absolute and
unconditional, upon failure by the Issuers to pay to the New Noteholders the
principal of, and premium, if any, and interest (including any accrued and
unpaid Default Interest) on, the New Limestone Notes as and when the same shall
become due and payable in accordance with their terms, or is intended to or
shall affect the relative rights of the holders of the New Limestone Notes and
creditors of the Guarantor, nor shall anything herein or therein prevent the New
Holders or the New Indenture Trustee on their behalf from exercising all
remedies otherwise permitted by applicable law upon default under this New
Indenture.

                  Without limiting the foregoing, nothing contained in this
Article III will restrict the right of the New Indenture Trustee or the New
Noteholders from taking any action to declare the El Paso Guarantee to be due
and payable prior to the Maturity Date after an acceleration of the New
Limestone Notes pursuant to Section 9.01 or to pursue any rights or remedies
hereunder.

                                       22
<PAGE>

                  SECTION 3.03. Limitation of Guarantor's Liability. Each of the
Guarantor and the New Indenture Trustee hereby confirms and, by its acceptance
of a New Limestone Note issued hereunder, each New Noteholder acknowledges and
agrees that it is the intention of such Person that the El Paso Guarantee not
constitute a fraudulent transfer or conveyance for purposes of any bankruptcy
law, the Uniform Fraudulent Conveyance Act, the Uniform Fraudulent Transfer Act
or any similar U.S. Federal or state or other applicable law. To effectuate the
foregoing intention, the New Noteholders and the Guarantor hereby irrevocably
agree that the obligations of the Guarantor under the El Paso Guarantee shall be
limited to the maximum amount as will, after giving effect to all other
contingent and fixed liabilities of the Guarantor, result in the obligations of
the Guarantor under the El Paso Guarantee not constituting such fraudulent
transfer or conveyance.

                  SECTION 3.04. Subordination of Subrogation and Other Rights.
The Guarantor hereby agrees that any claim against the Issuers that arises from
the payment, performance or enforcement of the Guarantor's obligations under the
El Paso Guarantee or this New Indenture, including, without limitation, any
right of subrogation, shall be subject and subordinate to the payment or
satisfaction in full of the New Limestone Notes (whether by payment, redemption
or otherwise), and the Guarantor shall not institute any proceedings to enforce
any such claim of the Guarantor until (x) the payment or satisfaction in full of
the New Limestone Notes (whether by payment, redemption or otherwise) and (y)
the cancellation of the outstanding Limestone Certificates in accordance with
Section 7.04 of the Limestone Trust Agreement or the receipt by the
Certificateholders of the EP Purchase Option Deposit Amount in accordance with
Section 7.02 of the Limestone Trust Agreement.

                  SECTION 3.05. Execution and Delivery of El Paso Guarantee. To
evidence its El Paso Guarantee set forth in this Article III, the Guarantor
hereby agrees to execute the El Paso Guarantee in substantially the form
included in Exhibit A, which shall be endorsed on each New Limestone Note
ordered to be authenticated and delivered by the New Indenture Trustee. The
Guarantor hereby agrees that its El Paso Guarantee shall remain in full force
and effect notwithstanding any failure to endorse on each New Limestone Note a
notation of the El Paso Guarantee. Any such endorsement bearing the manual or
facsimile signature of any individual who was at any time an Authorized Officer
of the Guarantor shall bind the Guarantor, notwithstanding the fact that such
individual has ceased to hold such office prior to the authentication and
delivery of the New Limestone Notes or did not hold such office at the date of
issuance of such New Limestone Notes. With the delivery of this New Indenture,
the Guarantor is furnishing, and from time to time thereafter may furnish, an
Officer's Certificate identifying and certifying the incumbency and specimen
signatures of the Authorized Officers of the Guarantor. Until the New Indenture
Trustee receives a subsequent Officer's Certificate of the Guarantor, the New
Indenture Trustee shall be entitled to rely on the last such Officer's
Certificate delivered to it for purposes of determining such Authorized
Officers. Typographical and other minor errors or defects in any signature shall
not affect the validity or enforceability of any El Paso Guarantee endorsed on
any New Limestone Note which has been duly authenticated and delivered by the
New Indenture Trustee.

                  SECTION 3.06. Notice to New Indenture Trustee. The Guarantor
shall give prompt written notice to the New Indenture Trustee of any fact known
to the Guarantor which prohibits the making of any payment to the New Indenture
Trustee in respect of the El Paso Guarantee pursuant to the provisions of this
Article III other than any agreement in effect on the date hereof.

                  SECTION 3.07. This Article Not to Prevent Events of Default.
The failure by the Guarantor to make a payment on account of principal of, and
premium, if any, or interest (including any accrued and unpaid Default Interest)
on, the New Limestone Notes by reason of any provision of this Article will not
be construed as preventing the occurrence of an Event of Default.

                  SECTION 3.08. New Notes Liquidity Payment. The Guarantor may
at any time, including upon receipt of a Shortfall Notice pursuant to Section
5.03, make a payment (a "New Notes Liquidity Payment") to the New Indenture
Trustee for deposit into the New Notes Account. Any such

                                       23
<PAGE>

payments will be used by the New Indenture Trustee to pay New Administrative
Expenses, Limestone Interest Amount and Default Interest due on the next
occurring semi-annual Limestone Note Payment Date.

                  SECTION 3.09. Additional Optional Payments by Guarantor. The
Guarantor may, at any time and from time to time, on behalf of Limestone, make
payments to the New Indenture Trustee for deposit into the New Notes Account for
the purpose of causing (i) an Optional Redemption of all or a portion of the New
Limestone Notes so long as the maturity of the New Limestone Notes has not been
accelerated as a result of an Event of Default, (ii) a Mandatory Redemption of
all of the New Limestone Notes if such payment occurs following the acceleration
of the New Limestone Notes as a result of an Event of Default but prior to the
120-day standstill referred to in Section 2.05(f)(ii) or (iii) the repayment of
the New Limestone Notes on the Maturity Date.

                                   ARTICLE IV

                                    ISSUANCE

                  SECTION 4.01. Conditions to Issuance. The issuance by the
Issuers and the authentication by the New Indenture Trustee of the New Limestone
Notes on initial issuance shall be subject to the satisfaction of the following
conditions on or prior to the Effective Date:

                  (a) the New Indenture Trustee shall have received fully
executed copies of each of the Transaction Documents to which Limestone, the
Co-Issuer or the Guarantor is a party (other than this New Indenture, the New
Limestone Notes and the Limestone Notes);

                  (b) the New Indenture Trustee shall have received certificates
from the Issuers and the Guarantor in form and substance reasonably satisfactory
to it and counsel for the Dealer Manager to the effect that the representations
and warranties of the Issuers and the Guarantor, as applicable, in the
Transaction Documents shall be true on and as of the Effective Date as if made
on and as of such date (except to the extent (i) specifically limited to an
earlier date, (ii) modified to give effect to the transactions contemplated by
the Transaction Documents or (iii) waived), and that the conditions precedent to
the issuance of the New Limestone Notes contained in any other Transaction
Document have been fulfilled (or waived);

                  (c) the New Indenture Trustee shall have received a
certificate of a Responsible Officer of El Paso in form and substance reasonably
satisfactory to it and counsel for the Dealer Manager to the effect that
immediately before and immediately after the issuance of the New Limestone Notes
on the Effective Date no Indenture Default or Event of Default shall have
occurred and be continuing;

                  (d) the New Indenture Trustee shall have received Opinions of
Counsel from Jones, Day, Reavis & Pogue, Richards, Layton & Finger, P.A.,
special Delaware counsel for Wilmington Trust Company, and Potter Anderson &
Corroon LLP, special Delaware counsel for the Issuers, in form and substance
reasonably satisfactory to the New Indenture Trustee and counsel for the Dealer
Manager;

                  (e) the exchange by the Issuers of the New Limestone Notes for
Limestone Notes (in accordance with the Exchange Offer) will not violate any
Applicable Law;

                  (f) there shall have occurred no invalidation of Section 4(2),
Rule 144A under the Securities Act by any court or any withdrawal or proposed
withdrawal of any rule or regulation under the Securities Act or the Exchange
Act by the SEC or any amendment or proposed amendment thereof by the SEC which
in the judgment of the Dealer Manager would materially impair the ability of the
New Holders of any beneficial interest in a Global Note to acquire, hold or
effect resales of the New Limestone Notes as contemplated herein;

                                       24
<PAGE>

                  (g) the New Indenture Trustee shall have received letters from
Moody's rating the New Limestone Notes "Baa2" or better and S&P rating the New
Limestone Notes "BBB" or better, in form and substance reasonably satisfactory
to the New Indenture Trustee and the Dealer Manager;

                  (h) the New Indenture Trustee shall have received a fully
executed Administrative Services Agreement signed by Limestone, the Co-Issuer
and the servicer named therein; and

                  (i) the New Indenture Trustee shall have received, from each
of the Issuers and the Guarantor, an Officer's Certificate attaching
Organizational Documents and resolutions, if applicable, relating to the
existence of the Issuers and the Guarantor, the trust authority or corporate
authority, as applicable, for and the validity of this New Indenture, the New
Limestone Notes and the other Transaction Documents, and any other matters
relevant hereto, all in form and substance reasonably satisfactory to the New
Indenture Trustee and counsel for the Dealer Manager.

                  SECTION 4.02. [Reserved].

                  SECTION 4.03. Waiver of Conditions to Issuance. If any of the
foregoing conditions shall not be satisfied upon the issuance of the New
Limestone Notes, such conditions shall be deemed to have been waived by the New
Indenture Trustee, the Dealer Manager and each New Noteholder by its acceptance
of its New Limestone Note.

                                    ARTICLE V

                                   THE ACCOUNT

                  SECTION 5.01. Establishment of New Notes Account.

                  (a) The New Indenture Trustee hereby acknowledges and agrees
that it has established a single, segregated trust account, which shall be
maintained at its Corporate Trust Office and which has been designated as the
"New Notes Account", for the benefit of the New Noteholders and over which the
New Indenture Trustee shall have exclusive control and the sole right of
withdrawal. The Issuers shall not have any rights to withdraw cash or other
property held in the New Notes Account. Payments shall be made from the New
Notes Account only in accordance with the provisions set forth below.

                  (b) The New Indenture Trustee will give notice to the Issuers,
the Guarantor and the New Noteholders of the location of the New Notes Account
and of any change thereof (provided that, subject to Section 11.03, no such
change shall be made without the prior approval of the Majority New
Noteholders), prior to the use thereof. Any income received by the New Indenture
Trustee with respect to the balance from time to time on deposit in the New
Notes Account, including any interest or capital gains on investments in
overnight securities made with amounts on deposit in the New Notes Account,
shall be credited to the New Notes Account.

                  (c) In the event of any conflict between this Section 5.01 (or
any portion thereof), any other provision of this New Indenture or any other
agreement now existing or hereafter entered into, the terms of this Section 5.01
shall prevail.

                  (d) The New Indenture Trustee shall make, to the extent
required or authorized hereunder, withdrawals from the New Notes Account: (i) to
withdraw any amount deposited in the New Notes Account and not required to be
deposited therein; (ii) to make required payments to the parties entitled
thereto pursuant to Section 5.04; and (iii) to clear and terminate the New Notes
Account upon satisfaction and discharge of this New Indenture pursuant to
Article X.

                                       25
<PAGE>

                  (e) The New Indenture Trustee shall be accountable for all
funds deposited into the New Notes Account, and shall pay and apply such funds
in accordance with the provisions of this Article V. Any amounts withdrawn under
Section 5.01(d)(i) shall be paid to the party entitled to such funds.

                  (f) Any and all amounts on deposit in the New Notes Account
shall, if not withdrawn on the day of deposit in accordance with this Article V,
be invested by the New Indenture Trustee in Financial Investments as directed in
writing by El Paso from time to time; provided that if an El Paso Debt
Obligation Repayment Event has occurred, such amounts shall be invested in
Financial Investments other than El Paso Debt Obligations and El Paso commercial
paper; provided further that upon the occurrence of an El Paso Debt Obligation
Repayment Event, El Paso shall no longer have the right to direct the New
Indenture Trustee with respect to the investment of the amounts on deposit in
the New Notes Account, and such amounts shall be invested by the New Indenture
Trustee in Financial Investments other than El Paso Debt Obligations and El Paso
commercial paper.

                  SECTION 5.02. New Notes Account. The New Indenture Trustee
shall deposit or cause to be deposited into the New Notes Account, not later
than 3:00 p.m. (New York City time) on each Limestone Note Payment Date, (i) all
amounts received by the New Indenture Trustee from the Limestone Trustee
pursuant to Sections 6.04(b) of the Limestone Trust Agreement, (ii) all New
Notes Liquidity Payments made by the Guarantor pursuant to Section 3.08, (iii)
all amounts received by the New Indenture Trustee from the Guarantor pursuant to
Section 3.09 and Section 14.01(a)(ii)(A) or Section 15.01(c)(i), (iv) all funds
received by the New Indenture Trustee pursuant to the El Paso Guarantee, as set
forth in Article III and (v) all amounts received by the New Indenture Trustee
from the Indenture Trustee pursuant to Section 5.04 of the Indenture.

                  SECTION 5.03. Shortfall. By 9:00 a.m. New York City time on
the Business Day prior to any semi-annual Limestone Note Payment Date, the New
Indenture Trustee shall give written notice to El Paso and the Issuers if the
Amount Available in the New Notes Account is not sufficient to pay the Limestone
Interest Amount and any New Administrative Expenses due and owing as of such
semi-annual Limestone Note Payment Date (a "Shortfall Notice"), which notice
shall specify the amount of the shortfall.

                  SECTION 5.04. Payments.

                  (a) Payments on Each Semi-Annual Limestone Note Payment Date.

                  (i) If no Shortfall Notice has been given pursuant to Section
5.03, or if a Shortfall Notice shall have been given but the amount specified in
the Shortfall Notice shall have been received by 3:00 p.m. New York City time on
the applicable semi-annual Limestone Note Payment Date, by 3:00 p.m. New York
City time on each semi-annual Limestone Note Payment Date, the New Indenture
Trustee shall withdraw the Amount Available from the New Notes Account and pay
such amount, in the manner and in the order of priority as follows:

                           first, from amounts credited to the New Notes
         Account, to the Paying Agent for the payment of any New Administrative
         Expenses;

                           second, from amounts credited to the New Notes
         Account, to the Paying Agent to be applied pro rata to the New
         Noteholders in the amount of any and all accrued and unpaid Limestone
         Interest Amount plus any accrued and unpaid Default Interest; and

                           third, any amounts remaining in the New Notes Account
         to be invested in accordance with Section 5.01(f).

                  (ii) If a Shortfall Notice has been given pursuant to Section
5.03 above and either (a) the Guarantor has made a New Notes Liquidity Payment
in an amount equal to the entire amount

                                       26
<PAGE>

specified in the Shortfall Notice or the amount specified in the Shortfall
Notice has otherwise been received on the first, second, third, fourth or fifth
Business Day after the relevant semi-annual Limestone Note Payment Date, then by
3:00 p.m. New York City time on the date such amount is received or (b) the
Guarantor has not made a New Notes Liquidity Payment in an amount equal to the
entire amount specified in the Shortfall Notice and the amount specified in the
Shortfall Notice has not otherwise been received by 3:00 p.m. on the fifth
Business Day after the relevant semi-annual Limestone Note Payment Date, then by
3:00 p.m. New York City time on such fifth Business Day after the relevant
semi-annual Limestone Note Payment Date, the New Indenture Trustee shall
withdraw the Amount Available from the New Notes Account and pay such amount in
the manner and in the order of priority as follows:

                           first, from amounts credited to the New Notes
         Account, to the Paying Agent for the payment of any New Administrative
         Expenses;

                           second, from amounts credited to the New Notes
         Account, to the Paying Agent to be applied pro rata to the New
         Noteholders in the amount of any and all accrued and unpaid Limestone
         Interest Amount plus any accrued and unpaid Default Interest; and

                           third, any amounts remaining in the New Notes Account
         to be invested in accordance with Section 5.01(f).

                  (iii) Each New Noteholder shall be deemed, by its acceptance
of a New Limestone Note, to agree that in case of any excess payment to it, it
shall promptly remit to the New Indenture Trustee for payment in accordance with
the terms of this Section 5.04 any such excess payment it has received. The New
Indenture Trustee shall promptly pay such amounts, when received, to any party
then not paid in full pursuant to this Section 5.04(a) and any remainder shall
be paid in accordance with priority third of Section 5.04(a)(ii).

                  (b) Payments on the Maturity Date. By 3:00 p.m. New York City
time on the Maturity Date, so long as (i) the New Limestone Notes have not been
accelerated as a result of the occurrence of an Event of Default and (ii) the
New Limestone Notes have not been redeemed in full, the New Indenture Trustee
shall withdraw the Amount Available from the New Notes Account and pay such
amounts, in the manner and in the order of priority as follows:

                           first, from amounts credited to the New Notes
         Account, to the Paying Agent for the payment of New Administrative
         Expenses;

                           second, from amounts credited to the New Notes
         Account, to the Paying Agent to be applied pro rata to the New
         Noteholders in the amount of any and all accrued and unpaid Limestone
         Interest Amount;

                           third, from amounts credited to the New Notes
         Account, to the Paying Agent to be applied pro rata to the New
         Noteholders as a payment of principal, until such principal is reduced
         to zero; and

                           fourth, any amounts remaining in the New Notes
         Account, to the Limestone Trustee for deposit into the Limestone
         Distribution Account pursuant to the Limestone Trust Agreement.

                  Each New Noteholder shall be deemed by its acceptance of a New
Limestone Note to agree, that in case of any excess payment to it, it shall
promptly remit to the New Indenture Trustee for payment in accordance with the
terms of this Section 5.04 any such excess payment it has received. The New
Indenture Trustee shall promptly pay such amounts, when received, to any party
then not paid in full pursuant to this Section 5.04(b), and any remainder in the
New Notes Account shall be paid in accordance with priority fourth of this
Section 5.04(b).

                                       27
<PAGE>

                  (c) Payments on certain Acceleration Dates, a Mandatory
Redemption Date or a Special Redemption Date. Upon (i) the occurrence of an
Event of Default and the acceleration of the New Limestone Notes as a result
thereof (other than an acceleration attributable to an Event of Default
described in Section 9.01(a)), (ii) a Mandatory Redemption pursuant to Article
XV or (iii) a Special Redemption pursuant to Article XV, by 3:00 p.m. (New York
City time) on such Limestone Note Payment Date, the New Indenture Trustee shall
withdraw the Amount Available from the New Notes Account and pay such amounts,
in the manner and in the order of priority as follows:

                           first, from amounts credited to the New Notes
         Account, to the Paying Agent for the payment of New Administrative
         Expenses;

                           second, from amounts credited to the New Notes
         Account, to the Paying Agent to be applied pro rata to the New
         Noteholders in the amount of any and all accrued and unpaid Limestone
         Interest Amount plus any accrued and unpaid Default Interest;

                           third, from amounts credited to the New Notes
         Account, to the Paying Agent to be applied pro rata to the New
         Noteholders as a payment of principal, until such principal is reduced
         to zero; and

                           fourth, any amounts remaining in the New Notes
         Account, to the Limestone Trustee for deposit into the Limestone
         Distribution Account pursuant to the Limestone Trust Agreement.

                  Each New Noteholder shall be deemed by its acceptance of a New
Limestone Note to agree, that in case of any excess payment to it, it shall
promptly remit to the New Indenture Trustee for payment in accordance with the
terms of this Section 5.04 any such excess payment it has received. The New
Indenture Trustee shall promptly pay the such amounts, when received, to any
party then not paid in full pursuant to this Section 5.04(c) and any remainder
shall be paid in accordance with priority fourth of this Section 5.04(c).

                  (d) Payments on certain Acceleration Dates and an Optional
Redemption Date. (i) On any Optional Redemption Date, if the New Limestone Notes
are to be redeemed in part by the Issuers in accordance with Article XIV, the
New Indenture Trustee shall withdraw the Amount Available from the New Notes
Account and pay such amounts, in the manner and in the order of priority as
follows:

                           first, from amounts credited to the New Notes
         Account, to the Paying Agent for the payment of New Administrative
         Expenses; and

                           second, from amounts credited to the New Notes
         Account, to the Paying Agent to be applied to the New Noteholders in
         accordance with this New Indenture as a payment of the Optional
         Redemption Price.

                  (ii) Upon (A) an acceleration of the New Limestone Notes
attributable to an Event of Default described in Section 9.01(a) or (B) any
Optional Redemption Date (if the New Limestone Notes are to be redeemed in full
by the Issuers in accordance with Article XIV), by 3:00 p.m. New York City time
on any such Limestone Note Payment Date, the New Indenture Trustee shall
withdraw the Amount Available from the New Notes Account and pay such amounts,
in the manner and in the order of priority as follows:

                           first, from amounts credited to the New Notes
         Account, to the Paying Agent for the payment of New Administrative
         Expenses;

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<PAGE>

                           second, from amounts credited to the New Notes
         Account, to the Paying Agent to be applied to the New Noteholders in
         accordance with this New Indenture as a payment of the Optional
         Redemption Price; and

                           third, any amounts remaining in the New Notes
         Account, to the Limestone Trustee for deposit into the Limestone
         Distribution Account pursuant to the Limestone Trust Agreement.

                  Each New Noteholder shall be deemed by its acceptance of a New
Limestone Note to agree, that in case of any excess payment to it, it shall
promptly remit to the New Indenture Trustee for payment in accordance with the
terms of this Section 5.04 any such excess payment it has received. The New
Indenture Trustee shall promptly pay such amounts, when received, to any party
then not paid in full pursuant to this Section 5.04(d) and the remainder shall
be paid in accordance with priority third of this Section 5.04(d)(ii).

                  (e) All payments made to New Noteholders on any semi-annual
Limestone Note Payment Date will be made to the New Noteholders of record at the
close of business on the March 1 or September 1, as applicable, next preceding
such Limestone Note Payment Date (the "Record Date").

                  (f) The New Noteholders shall be entitled to receive payments
hereunder on any Limestone Note Payment Date by wire transfer to the account
specified in writing by the applicable New Noteholder to the New Indenture
Trustee. In each case, the account must be specified in writing no later than
the Record Date for the applicable Limestone Note Payment Date on which wire
transfers will commence. Unless such instruction is revoked, any such
instruction made by such New Holder with respect to such New Limestone Notes
shall remain in effect with respect to any future payments with respect to such
New Limestone Note payable to such New Holder.

                  (g) If the New Indenture Trustee shall not have received a
distribution or payment with respect to the El Paso Guarantee by 5:00 p.m. New
York City time on the Business Day after the date on which demand for payment
was made pursuant to Section 3.01, the New Indenture Trustee shall promptly and
in no event later than 10:00 a.m. on the following Business Day give written
notice thereof to the Guarantor and the New Noteholders.

                  (h) If on any day on which a distribution under this Section
5.04 is required to be made, the New Indenture Trustee ascertains that the
Amount Available in the New Notes Account is then insufficient to pay in full
the amount required to be paid from the New Notes Account, then, if any
investments are held in the New Notes Account, the New Indenture Trustee shall
sell or otherwise liquidate all or such portion of such investments as is
necessary to pay in full the required amount.

                  SECTION 5.05. Report to New Noteholders.

                  (a) Within five Business Days following every Limestone Note
Payment Date commencing September 15, 2002, the New Indenture Trustee shall
deliver to the Issuers, El Paso, each New Noteholder and, if so requested, each
owner of a beneficial interest in a Global Note, a statement (an "Account
Statement") setting forth the status of the New Notes Account showing, for the
period covered by such statement, deposits in or withdrawals from the New Notes
Account and proceeds of investments of funds in the New Notes Account. The
Account Statement shall also set forth the following information:

                           (i) the amounts in the New Notes Account as of such
         Limestone Note Payment Date prior to giving effect to payments made on
         such Limestone Note Payment Date; and

                                       29
<PAGE>

                           (ii) the amounts of such funds in the New Notes
        Account pursuant to Section 5.04.

                  Within a reasonable period of time after the end of each
calendar year, the New Indenture Trustee will furnish a report to the Issuers,
the Rating Agencies, each New Noteholder of record at any time during such
calendar year and, subject to Section 5.05(b), each owner of a beneficial
interest in a Global Note who so requests, as to aggregate amounts reported
pursuant to (i) and (ii) above for such calendar year.

                  (b) With respect to the information and documents required to
be delivered pursuant to clause (a) above, the New Indenture Trustee may require
each owner of a beneficial interest in a Global Note requesting such information
to provide evidence satisfactory to the New Indenture Trustee of such Person's
interest in a Global Note before delivering the requested information to such
Person.

                  (c) The New Indenture Trustee shall, subject to Article XI,
use its reasonable efforts to obtain any information it is required under this
New Indenture to obtain in the manner provided by this New Indenture.

                  (d) Consistent with the provisions of Section 2.08(c), the New
Indenture Trustee shall (i) furnish to the New Noteholders and any taxing
authority, within the time periods required by applicable law, such forms of
information as is required by applicable Federal or state tax law, including,
but not limited to appropriate Forms 1099 and (ii) shall also provide such other
information as may be reasonably requested by any New Noteholder, at such New
Noteholder's expense, to enable the New Noteholder to prepare its tax returns.

                  SECTION 5.06.Termination. Upon repayment in full of the New
Limestone Notes and all other amounts due and owing under this New Indenture,
this New Indenture will terminate and be discharged in accordance with Article
X.

                                   ARTICLE VI

                        REPRESENTATIONS AND WARRANTIES OF
                                   THE ISSUERS

                  SECTION 6.01. Representations and Warranties. Each of
Limestone and the Co-Issuer, as applicable, represents and warrants to the New
Indenture Trustee that, as of the Effective Date, that:

                  (a) Existence and Power. Limestone is a business trust duly
organized, validly existing and in good standing under the laws of the State of
Delaware and has all requisite trust powers and all material Permits required to
carry on its business as now conducted and as contemplated by the Transaction
Documents. The Co-Issuer is a corporation duly incorporated, validly existing
and in good standing under the laws of the State of Delaware and has all
requisite corporate powers and all material Permits required to carry on its
business as now conducted and as contemplated by the Transaction Documents.

                  (b) Special Purpose Status. Limestone has not engaged in any
activities since its organization (other than those incidental to its
organization, activities referred to in or contemplated by the Phase II
Participation Agreement, the Original Participation Agreement, other appropriate
steps including the issuance of certificates representing beneficial ownership
interests in Limestone and arrangements for the payment of fees to its trustees,
the authorization and the issuance of the Limestone Notes, the New Limestone
Notes and the Limestone Certificates, the execution of the Transaction Documents
to which it is a party executed on or prior to the date hereof, activities in
connection with the Exchange Offer and consent solicitation and the activities
referred to in or contemplated by the Offering

                                       30
<PAGE>

Circular and Consent Solicitation Statement or such Transaction Documents), and
has not made any distributions since its organization (other than any
distributions made pursuant to Section 5.04(a) of the Indenture on any
semi-annual Limestone Note Payment Date and the distributions made to Electron
on January 18, 2000 in the amount of $33,578.13 and March 10, 2000 in the amount
of $1,008,155.58, each with respect to a special tax distribution pursuant to
Section 5.01(c) of the Third Amended and Restated Limited Liability Company
Agreement of Chaparral). The Co-Issuer has not engaged in any activities since
its incorporation (other than those incidental to its incorporation, other
appropriate corporate steps including the issuance of stock to Limestone and
arrangements for the payment of fees to its directors, the authorization and the
issuance of the Limestone Notes and the New Limestone Notes, the execution of
the Transaction Documents to which it is a party executed on or prior to the
date hereof, activities in connection with the Exchange Offer and consent
solicitation and the activities referred to in or contemplated by the Offering
Circular and Consent Solicitation Statement or such Transaction Documents), and
has not paid any dividends or made any distributions since its incorporation
(other than any distributions made pursuant to Section 5.04(a) of the Indenture
on any semi-annual Limestone Note Payment Date).

                  (c) Trust or Corporate and Governmental Authorization; No
Contravention. The execution, delivery and performance by Limestone of each of
the Transaction Documents (other than the Note Purchase Agreement and the Dealer
Manager Agreement) to which it is a party are within Limestone's trust powers,
have been duly authorized by all necessary trust action, require in respect of
Limestone no action by or in respect of, or filing (except Uniform Commercial
Code continuation statements to be filed in the future) with, any Governmental
Authority that has not been taken or made and do not contravene, or constitute a
default under, any provision of Applicable Law in effect on the Effective Date
or of Limestone's Certificate of Trust or the Limestone Trust Agreement, or of
any agreement or other instrument binding upon Limestone or result in the
creation or imposition of any Lien on any asset of Limestone, except for
Permitted Liens of the type described in clause (iii) of the definition thereof.
The execution, delivery and performance by the Co-Issuer of each of the
Transaction Documents (other than the Note Purchase Agreement and the Dealer
Manager Agreement) to which it is a party are within the Co-Issuer's corporate
powers, have been duly authorized by all necessary action, require no corporate
action by or in respect of, or filing (except Uniform Commercial Code
continuation statements to be filed in the future) with, any Governmental
Authority that has not been taken or made and do not contravene, or constitute a
default under, any provision of Applicable Law in effect on the Effective Date
or of the Co-Issuer's Certificate of Incorporation or Bylaws, or of any
agreement or other instrument binding upon the Co-Issuer or result in the
creation or imposition of any Lien on any asset of the Co-Issuer, except for
Permitted Liens of the type described in clause (iii) of the definition thereof.

                  (d) Binding Effect. Each of the Transaction Documents (other
than the Note Purchase Agreement and the Dealer Manager Agreement) to which
Limestone or the Co-Issuer is a party has been duly executed and delivered by
Limestone or the Co-Issuer, and, subject to the due execution and delivery by
the other parties thereto, each such Transaction Document constitutes (or in the
case of the New Limestone Notes, when duly authenticated, issued and delivered
in accordance with this New Indenture and the Dealer Manager Agreement, will
constitute) a legal, valid and binding obligation of Limestone or the Co-Issuer,
as the case may be, enforceable against Limestone or the Co-Issuer, as the case
may be, in accordance with its terms except as the enforceability thereof may be
limited by applicable bankruptcy, insolvency, reorganization, moratorium or
other similar laws affecting the enforcement of creditors' rights generally and
general equitable principles (whether enforcement is sought by proceedings in
equity or at law).

                  (e) [Reserved].

                  (f) No Consents. The execution, delivery and performance by
each of Limestone and the Co-Issuer of each Transaction Document (other than the
Note Purchase Agreement and the Dealer Manager Agreement) to which Limestone or
the Co-Issuer, as the case may be, is a party and the offering

                                       31
<PAGE>

of the New Limestone Notes by the Issuers in exchange for Limestone Notes (in
accordance with the Exchange Offer) do not require the consent or the approval
or authorization of, or any filing, registration or qualification with, any
Person or any Governmental Authority on the part of Limestone or the Co-Issuer,
as applicable, as a condition to such execution, delivery and performance by it
as and when required that has not been obtained, given or taken except where the
failure to obtain such consent, approval or authorization, or make such filing,
registration or qualification would not have an Issuer Material Adverse Effect.

                  (g) Litigation. There is no Proceeding pending against, or,
after reasonable inquiry, to the actual knowledge of any Responsible Officer of
Limestone or the Co-Issuer, threatened against, the Issuers before any
Governmental Authority.

                  (h) Tax Claims. There is no Tax claim pending against or,
after reasonable inquiry, to the actual knowledge of any Responsible Officer of
either Limestone or the Co-Issuer, threatened against the Issuers.

                  (i) Payment of Taxes. The Issuers have each paid all Taxes
which they are required to have paid prior to the Effective Date.

                  (j) Not an Investment Company. Neither Limestone nor the
Co-Issuer will be required to register as an "investment company" within the
meaning of the Investment Company Act, and neither will become such as a result
of the issuance and sale of the New Limestone Notes or the other transactions
contemplated by the Transaction Documents.

                  (k) [Reserved].

                  (l) No Conflict. Neither the issuance or delivery of the New
Limestone Notes nor the consummation of any other of the transactions
contemplated herein, nor compliance with the provisions of this New Indenture,
will conflict with or result in, the breach of any material term or provision of
any agreements to which Limestone or the Co-Issuer is a party, or constitute a
violation of any Applicable Law.

                  (m) [Reserved].

                  (n) Compliance. The Issuers are not in breach or violation of
or in default (nor, after reasonable inquiry, to the actual knowledge of a
Responsible Officer of either Limestone or the Co-Issuer, has an event occurred
that with notice or lapse of time or both would constitute a default) under the
terms of (i) their Organizational Documents, (ii) any of the Transaction
Documents (other than the Note Purchase Agreement and the Dealer Manager
Agreement), (iii) any other agreements to which they are a party or (iv) any
Applicable Law, the default in or the breach or violation of which in the case
of clause (ii), clause (iii) and clause (iv) would have an Issuer Material
Adverse Effect.

                  (o) No Defaults. To the best of the Issuers' knowledge, no
Event of Default has occurred and is continuing and no condition, event or act
has occurred and is continuing that with the giving of notice and/or the lapse
of time and/or any determination or certification would constitute an Event of
Default.

                  (p) Indebtedness. Neither Issuer has created, assumed or
incurred any Indebtedness other than the Limestone Notes and the New Limestone
Notes and, in the case of Limestone, loans repaid in full in accordance with the
Phase II Participation Agreement and the Participation Agreement.

                  (q) Employees, Subsidiaries. Limestone has no employees, and
other than the Co-Issuer, no subsidiaries and no place of business outside of
the State of Delaware. The Co-Issuer has no employees, no subsidiaries and no
place of business outside of the State of Delaware.

                                       32
<PAGE>

                  (r) PUHCA. Neither Issuer is subject to regulation as a
"holding company," or a "subsidiary company" or an "affiliate" of a "holding
company," in each case as such terms are defined in the PUHCA.

                  (s) Federal Power Act. None of Limestone and the Co-Issuer is
in the business of producing, transmitting or selling electrical power and the
principal business of each Issuer is other than that of a "public utility" as
such term is defined in Section 201 of the FPA and the orders of the FERC
interpreting such section.

                  (t) Securities Act. Assuming that the representations of the
initial New Noteholders relating to matters of securities law set forth in the
Offering Circular and Consent Solicitation and/or the Letter of Transmittal are
true and correct, the exchange of the New Limestone Notes for the Limestone
Notes by the Issuers in the manner contemplated by the Offering Circular and
Consent Solicitation and the Dealer Manager Agreement will be exempt from the
registration requirements of the Securities Act by reason of Section 4(2)
thereof.

                  SECTION 6.02.Survival of Representations and Warranties. It is
understood and agreed that the representations and warranties set forth in
Section 6.01 shall survive the issuance of the New Limestone Notes. Upon actual
knowledge by the Issuers or a Responsible Officer of the New Indenture Trustee
of a breach of any of such representations and warranties, the party discovering
such breach shall give prompt written notice to the other parties and to the New
Noteholders.

                                   ARTICLE VII

                   COVENANTS OF THE ISSUERS AND THE GUARANTOR

                  SECTION 7.01. Covenants of the Issuers and the Guarantor. The
Issuers agree with respect to themselves and, to the extent applicable, any
other party to a Transaction Document (other than the Guarantor) and the
Guarantor agrees with respect to itself only, as applicable, that so long as any
amount payable hereunder or under any New Limestone Note remains unpaid:

                  (a) Information. The Issuers will at all times furnish to the
New Indenture Trustee such information as the New Indenture Trustee may
reasonably request for the purpose of the discharge of the trusts, powers,
rights, duties, authorities and discretions vested in it hereunder or under any
other Transaction Document (other than the Note Purchase Agreement and the
Dealer Manager Agreement) or by operation of law.

                  (b) Reporting Requirements. The Issuers and the Guarantor
shall furnish or cause to be furnished to the New Indenture Trustee who shall
furnish to El Paso, the Rating Agencies and the New Noteholders the following;
provided that, so long as the Guarantor is subject to Section 13 or 15(d) of the
Exchange Act, the Guarantor shall not be required to comply with clauses (i) and
(ii) below; provided, further, that the Guarantor shall not be required to
comply with clause (iv) below:

                           (i) as soon as available and in any event within 60
         days after the end of the first, second and third fiscal quarters of
         each of Limestone, Chaparral and the Guarantor, an unaudited
         consolidated balance sheet of each of Limestone, Chaparral and the
         Guarantor as of the end of such quarter and the related consolidated
         statements of income and cash flows for such quarter and for the
         portion of the fiscal year ending with the last day of such quarter and
         beginning with the first fiscal quarter ending in 2001, setting forth
         in each case in comparative form corresponding unaudited figures for
         the corresponding fiscal period of the preceding year, if any; provided
         that such financial statements need not include footnote disclosure and
         may be subject to ordinary year-end adjustment;

                                       33
<PAGE>

                           (ii) as soon as available and in any event within 120
         days after the end of each fiscal year of each of Limestone, Chaparral
         and the Guarantor, audited consolidated financial statements of each of
         Limestone, Chaparral and the Guarantor, prepared in accordance with
         GAAP, together with an unqualified audit opinion of
         PricewaterhouseCoopers LLP or another firm of independent certified
         public accountants of recognized national standing and an Issuers'
         Certificate stating, to its actual knowledge, (a) that no Indenture
         Default or Event of Default has occurred or is continuing, (b) if an
         Indenture Default or Event of Default has occurred and is continuing, a
         statement as to the nature thereof and what action the Issuers are
         taking or propose to take in respect thereof and (c) that no event has
         occurred or remains by reason of which payments on account of the
         principal of or interest, if any, on the New Limestone Notes are
         prohibited or if such event has occurred, a statement as to the nature
         thereof and what action the Issuers are taking or propose to take with
         respect thereto;

                           (iii) promptly and in any event within 10 Business
         Days after any of Limestone, the Co-Issuer or the Guarantor has actual
         knowledge thereof, written notice of the occurrence of any event or
         condition which constitutes an Indenture Default, an Event of Default
         or a Specified Equity Event, specifically stating that such event or
         condition has occurred and describing it and any action being or
         proposed to be taken with respect thereto; and

                           (iv) promptly and in any event within 10 Business
         Days after either Limestone or the Co-Issuer has actual knowledge
         thereof, written notice of the occurrence of any material default under
         any Transaction Document (other than the Note Purchase Agreement and
         the Dealer Manager Agreement), the commencement of any material
         actions, suits and other proceedings instituted against either
         Limestone or the Co-Issuer, or the occurrence of any event or condition
         that is reasonably likely to have an Issuer Material Adverse Effect.

                  With respect to the information and documents required to be
delivered pursuant to this Section 7.01(b), the New Indenture Trustee may
require each owner of a beneficial interest in a Global Note requesting such
information to provide evidence satisfactory to the New Indenture Trustee of
such Person's interest in a Global Note before delivering the requested
information to such Person. Delivery of such information, documents or notices
to the New Indenture Trustee shall be for informational purposes only and the
New Indenture Trustee's receipt of such shall not constitute constructive notice
of any information contained therein or determinable from information contained
therein, including the Issuers' compliance with any of their covenants hereunder
(as to which the New Indenture Trustee is entitled to rely exclusively on
Issuers' Certificates).

                  (c) Maintenance of Books and Records. The Issuers will
maintain their books and records in accordance with GAAP.

                  (d) [Reserved].

                  (e) Payment of Obligations. The Issuers and the Guarantor will
pay and discharge in full their respective obligations hereunder, under the New
Limestone Notes and the other Transaction Documents (other than the Note
Purchase Agreement and the Dealer Manager Agreement).

                  (f) Limitation on Business Activities of Limestone. Limestone
shall not hold any material assets (other than its interest in the Co-Issuer,
its interest in Chaparral, its interests under the Transaction Documents and
Financial Investments as contemplated by the Transaction Documents), become
liable for any material obligations (other than the Limestone Notes and the New
Limestone Notes), engage in any trade or business, or conduct any business
activity other than the issuance of the Limestone Certificates, the incurrence
of indebtedness as a co-obligor of the Limestone Notes and the New Limestone
Notes, the activities contemplated in this New Indenture, the Participation
Agreement, the Security Agreement and any other Transaction Document and the
activities incidental thereto.

                                       34
<PAGE>

                  (g) Limitation on Business Activities of the Co-Issuer. The
Co-Issuer shall not hold any material assets, become liable for any material
obligations (other than the Limestone Notes and the New Limestone Notes), engage
in any trade or business, or conduct any business activity, other than the
issuance of equity interests to Limestone, the incurrence of indebtedness as a
co-obligor of the Limestone Notes and the New Limestone Notes, the activities
contemplated in this New Indenture and any other Transaction Document and
activities incidental thereto. Limestone shall not engage in any transactions
with the Co-Issuer in violation of the immediately preceding sentence.

                  (h) [Reserved].

                  (i) [Reserved].

                  (j) [Reserved].

                  (k) Direction. The Issuers shall take all steps as the New
Indenture Trustee may reasonably require at any time or times to give effect to
the Transaction Documents; provided that any costs and expenses of taking such
steps shall be included in the New Administrative Expenses due and payable on
the next succeeding Limestone Note Payment Date. The Guarantor shall take all
steps as the New Indenture Trustee may reasonably require at any time or times
to give effect to any of its obligations under this New Indenture and the New
Limestone Notes; provided that any costs and expenses of taking such steps
(other than costs and expenses of the Guarantor) shall be included in the New
Administrative Expenses due and payable on the next succeeding Limestone Note
Payment Date.

                  (l) Conduct of Business and Maintenance of Existence. The
Issuers will carry on their business in a proper and efficient manner, to the
extent permitted under this New Indenture. Subject to the terms of Section
7.01(p), the Issuers will keep in full effect their legal existence, material
rights (charter, if applicable, and statutory) and material franchises as a
business trust or corporation, as applicable, under the laws of the State of
Delaware and, at the request of the New Indenture Trustee, will obtain and
preserve their qualification to do business as a foreign trust or foreign
corporation, as applicable, in each jurisdiction in which such qualification is
or shall be necessary to protect the validity and enforceability of this New
Indenture and to perform their respective duties under this New Indenture.

                  (m) Compliance with Laws. Each of Limestone and the Co-Issuer
will comply in all material respects with all Applicable Laws in the
jurisdiction of its organization or incorporation except where the necessity of
compliance therewith is contested in good faith by appropriate proceedings or
where the failure to so comply would not reasonably be expected to have an
Issuer Material Adverse Effect.

                  (n) Investments; No Subsidiaries. Other than as contemplated
by the Transaction Documents, the Issuers will not make or acquire any
Investment in any Person other than Chaparral and, in the case of Limestone, the
Co-Issuer and Financial Investments. Without limitation of the foregoing, the
Co-Issuer shall have no subsidiaries.

                  (o) Indebtedness. The Issuers will not create, assume or incur
any Indebtedness other than the Limestone Notes and the New Limestone Notes.

                  (p) Consolidation or Merger. Any Person into which any of
Limestone or the Co-Issuer may be merged or consolidated, or any Person
resulting from any merger or consolidation to which any of Limestone or the
Co-Issuer shall be a party, or any Person succeeding to the business of any of
Limestone or the Co-Issuer, shall be the successor of Limestone or the
Co-Issuer, as applicable, hereunder, without the execution or filing of any
paper or any further act on the part of any of the parties hereto; provided that
each Rating Agency confirms that its then current rating on the New Limestone
Notes shall not be withdrawn or downgraded.

                                       35
<PAGE>

                  (q) [Reserved].

                  (r) Amendment of Transaction Documents. Except for amendments,
modifications and supplements to this New Indenture contemplated in Article XII,
the Issuers will not agree or consent to any amendment, modification or waiver
of any provision of any Transaction Document (other than the Note Purchase
Agreement, the Dealer Manager Agreement, the Overfund Trust Agreement, the
Security Agreement, the Share Trust Agreement, the Remarketing Agreement, the El
Paso Preferred Stock Certificate of Designation and the Participation Agreement)
without the consent of the New Indenture Trustee acting at the written direction
of the Majority New Holders unless the New Indenture Trustee receives a legal
opinion of nationally recognized outside counsel experienced in structured
finance (including Jones Day, Reavis & Pogue) to the effect that such amendment,
modification or waiver will not materially adversely affect the rights or
obligations of the New Noteholders. Neither Limestone nor the Co-Issuer shall
amend or modify, or consent to amend or modify, the Certificate of Trust of
Limestone or the Certificate of Incorporation of the Co-Issuer without the
written consent of the Majority New Holders (except in either case, as required
by law or with respect to its registered agent or office in the State of
Delaware).

                  (s) Assignment of Transaction Documents. Except for
assignments contemplated by this New Indenture (which shall include any
assignments made in connection with any consolidation or merger permitted by
Section 7.01(p)), the Issuers will not assign their rights under any of the
Transaction Documents (other than the Note Purchase Agreement and the Dealer
Manager Agreement) to which they are a party without the prior written consent
of the Majority New Holders.

                  (t) Rule 144A. The Issuers and the Guarantor will furnish or
cause to be furnished promptly upon the request of a New Noteholder or a
prospective transferee, at any time when the Issuers or the Guarantor, as the
case may be, are not subject to Section 13 or 15(d) of the Exchange Act,
information specified in Rule 144A(d)(4)(i) and (ii) under the Securities Act,
to such New Noteholder or to a prospective transferee of a New Limestone Note or
interests in such New Limestone Note designated by such New Noteholder, as the
case may be, in connection with the resale pursuant to Rule 144A of such New
Limestone Note or such interests by such New Noteholder; provided, however, that
the Issuers and the Guarantor shall not be required to furnish such information
in connection with any request made after the date which is two years after the
later to occur of (i) the Effective Date and (ii) the date such New Limestone
Note was last acquired from an "affiliate" of any of Limestone, the Co-Issuer or
the Guarantor within the meaning of Rule 144.

                  (u) Restrictions on Certain Actions. The Issuers and the
Guarantor will not take, or knowingly permit to be taken, any action that would
terminate or discharge or prejudice the validity or effectiveness of any of the
Transaction Documents (other than the Note Purchase Agreement, the Dealer
Manager Agreement, the Overfund Trust Agreement, the Security Agreement, the
Share Trust Agreement, the El Paso Preferred Stock Certificate of Designation
and the Participation Agreement) except as permitted or contemplated by this New
Indenture or the other Transaction Documents.

                  (v) Transaction Documents. Each of Limestone, the Co-Issuer
and the Guarantor will enter into and perform all of its material obligations
under each Transaction Document (other than the Note Purchase Agreement and the
Dealer Manager Agreement) to which it is a party.

                  (w) Dealings with Ownership Interests and Stock. Limestone
shall not issue, deliver or sell any additional ownership interests. The
Co-Issuer shall not issue, deliver or sell any additional shares, except to
Limestone.

                  (x) Section 3(c)(7) Reminder Notice. Limestone shall furnish
or cause to be furnished to the New Indenture Trustee who shall furnish to the
New Noteholders, simultaneously with

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<PAGE>

each report required to be furnished pursuant to Section 7.01(b)(i) and (ii), a
Section 3(c)(7) Reminder Notice substantially in the form attached as Exhibit E
hereto.

                  (y) Transfer Restrictions. The Issuers shall not remove the
Transfer Restriction Legend or the QP Legend from the New Limestone Notes at any
time.

                  (z) DTC Actions. Limestone shall direct DTC to take the
following steps in connection with the Restricted Global Notes:

                           (i) Limestone shall direct DTC to include the "3c7"
         marker in the DTC 20-character security descriptor and the 48-character
         additional descriptor for the Restricted Global Notes in order to
         indicate that sales are limited to Qualified Purchasers.

                           (ii) Limestone shall direct DTC to cause each
         physical DTC delivery order ticket delivered by DTC to purchasers to
         contain the 20-character security descriptor and shall direct DTC to
         cause each DTC delivery order ticket delivered by DTC to purchasers in
         electronic form to contain the "3c7" indicator and the related user
         manual for participants.

                           (iii) On or prior to the Effective Date, Limestone
         will instruct DTC to send an "Important Notice" to all DTC Participants
         in connection with the offering of Restricted Global Notes. The
         "Important Notice" will be in substantially the form of Exhibit D
         hereto and will notify DTC's Participants that the Restricted Global
         Notes are Section 3(c)(7) securities issued by a U.S. Person.

                           (iv) Limestone will request DTC to include the
         Restricted Global Notes in DTC's "Reference Directory" of Section
         3(c)(7) offerings.

                           (v) Limestone will from time to time (upon the
         request of the New Indenture Trustee or the Note Registrar) request DTC
         to deliver to Limestone a list of all DTC Participants holding an
         interest in the Restricted Global Notes.

                  (aa) Bloomberg Screens, Etc. Limestone will from time to time
request all third-party vendors to include on screens maintained by such vendors
appropriate legends regarding Rule 144A and Section 3(c)(7) restrictions on the
Restricted Global Notes. Without limiting the foregoing, Limestone will request
that Bloomberg, L.P. include the following on each Bloomberg screen containing
information about the Restricted Global Notes:

                           (i) The bottom of the "Security Display" page
         describing the Rule 144A Notes should state: "Iss'd Under 144A/3c7".

                           (ii) Reserved.

                           (iii) The "Security Display" page should have a
         flashing red indicator stating "See Other Available Information."

                           (iv) Such indicator for the Rule 144A Notes should
         link to an "Additional Security Information" page, which should state
         that the Rule 144A Notes "are being offered in reliance on the
         exemption from registration under Rule 144A of the Securities Act of
         1933 to persons that are both (1) qualified institutional buyers (as
         defined in Rule 144A under the Securities Act) and (2) qualified
         purchasers (as defined under Section 3(c)(7) of the Investment Company
         Act of 1940)."

                           (v) Reserved.

                                       37
<PAGE>

                           (vi) The "Disclaimer" page for the Restricted Notes
         should state that the Restricted Notes "will not be and have not been
         registered under the Securities Act of 1933, as amended, and the
         Issuers have not been registered under the Investment Company Act of
         1940, as amended, and these securities may not be offered or sold in
         the United States absent registration or an applicable exemption from
         registration requirements and any such offer or sale of these
         securities must be in accordance with Section 3(c)(7) of the Investment
         Company Act of 1940."

                  (bb) CUSIP. The Issuer will cause each "CUSIP" number obtained
for a Restricted Global Note to have an attached "fixed field" that contains
"3c7" and "144A" indicators.

                  (cc) Existence. Subject to Section 7.01(dd) and Section
7.01(ee), the Guarantor shall do or cause to be done all things necessary to
preserve and keep in full force and effect its existence, rights (charter and
statutory) and franchises; provided, however, that the Guarantor shall not be
required to preserve any such right or franchise if it shall determine that the
preservation thereof is no longer desirable in the conduct of the business of
the Guarantor.

                  (dd) Consolidation, Merger, Conveyance, Transfer or Lease. The
Guarantor shall not consolidate with or merge into any other Person or sell,
lease or transfer its properties and assets as, or substantially as, an entirety
to any Person, unless:

                           (i)(A) in the case of a merger, the Guarantor is the
         surviving entity or (B) the Person formed by such consolidation or into
         which the Guarantor is merged or the Person which acquires by sale or
         transfer, or which leases, the properties and assets of the Guarantor
         as, or substantially as, an entirety shall expressly assume, by an
         indenture supplemental hereto, executed and delivered to the New
         Indenture Trustee, in form reasonably satisfactory to the New Indenture
         Trustee, the performance or observance of every covenant, condition or
         other obligation of this New Indenture, the New Limestone Notes and the
         El Paso Guarantee on the part of the Guarantor to be performed or
         observed;

                           (ii) immediately after giving effect to such
         transaction, no Event of Default or event that, after notice or lapse
         of time or both would become an Event of Default, exists with respect
         to the Guarantor's obligations under this New Indenture or the El Paso
         Guarantee; and

                           (iii) the Guarantor has delivered to the New
         Indenture Trustee an Officer's Certificate and an Opinion of Counsel,
         each stating that such consolidation, merger, sale, transfer or lease
         and the supplemental indenture required in connection with such
         transaction comply with this Section 7.01(dd) and Section 7.01(ee) and
         that all conditions precedent herein provided for relating to such
         transaction have been complied with.

                  (ee) Successor Substituted. Upon any consolidation of the
Guarantor with, or merger of the Guarantor into, any other Person or any sale,
transfer or lease of the properties and assets of the Guarantor as, or
substantially as, an entirety in accordance with Section 7.01(dd), the successor
Person formed by such consolidation or into which the Guarantor is merged or to
which such sale, transfer or lease is made shall succeed to, and be substituted
for, and may exercise every right and power of, the Guarantor under this New
Indenture, the New Limestone Notes and the El Paso Guarantee with the same
effect as if such successor Person had been named originally herein, and
thereafter, except in the case of a lease, the predecessor Person shall be
relieved of all obligations and covenants under this New Indenture, the New
Limestone Notes and the El Paso Guarantee.

                  (ff) Limitations on Liens. The Guarantor shall not, nor shall
it permit any Restricted Subsidiary to, create, assume, incur or suffer to exist
any Lien upon any Principal Property, whether owned or leased on the date hereof
or thereafter acquired, to secure any Debt of the Guarantor or any

                                       38
<PAGE>

other Person (other than the El Paso Guarantee), without in any such case making
effective provision whereby the El Paso Guarantee shall be secured equally and
ratably with, or prior to, such Debt, so long as such Debt shall be so secured.
This restriction shall not apply to:

                           (i) any Lien upon any property or assets of the
         Guarantor or any Restricted Subsidiary in existence on the Effective
         Date or created pursuant to an "after-acquired property" clause or
         similar term in existence on the Effective Date or any mortgage, pledge
         agreement, security agreement or other similar instrument in existence
         on the Effective Date;

                           (ii) any Lien upon any property or assets created at
         the time of acquisition of such property or assets by the Guarantor or
         any Restricted Subsidiary or within one year after such time to secure
         all or a portion of the purchase price for such property or assets or
         Debt incurred to finance such purchase price, whether such Debt was
         incurred prior to, at the time of or within one year of such
         acquisition;

                           (iii) any Lien upon any property or assets existing
         thereon at the time of the acquisition thereof by the Guarantor or any
         Restricted Subsidiary (whether or not the obligations secured thereby
         are assumed by the Guarantor or any Restricted Subsidiary);

                           (iv) any Lien upon any property or assets of a Person
         existing thereon at the time such Person becomes a Restricted
         Subsidiary by acquisition, merger or otherwise;

                           (v) the assumption by the Guarantor or any Restricted
         Subsidiary of obligations secured by any Lien existing at the time of
         the acquisition by the Guarantor or any Restricted Subsidiary of the
         property or assets subject to such Lien or at the time of the
         acquisition of the Person which owns such property or assets;

                           (vi) any Lien on property to secure all or part of
         the costs of construction or improvements thereon or to secure Debt
         incurred prior to, at the time of or within one year after the
         completion of such construction or making of such improvements, to
         provide funds for any such purpose;

                           (vii) any Lien on any oil, gas, mineral and
         processing and other plant properties to secure the payment of costs,
         expenses or liabilities incurred under any lease or grant or operating
         or other similar agreement in connection with or incident to the
         exploration, development, maintenance or operation of such properties;

                           (viii) any Lien arising from or in connection with a
         conveyance by the Guarantor or any Restricted Subsidiary of any
         production payment with respect to oil, gas, natural gas, carbon
         dioxide, sulphur, helium, coal, metals, minerals, steam, timber or
         other natural resources;

                           (ix) any Lien in favor of the Guarantor or any
         Restricted Subsidiary;

                           (x) any Lien created or assumed by the Guarantor or
         any Restricted Subsidiary in connection with the issuance of Debt the
         interest on which is excludable from gross income of the holder of such
         Debt pursuant to the Code or any successor statute, for the purpose of
         financing, in whole or in part, the acquisition or construction of
         property or assets to be used by the Guarantor or any Subsidiary;

                           (xi) any Lien upon property or assets of any foreign
         Restricted Subsidiary to secure Debt of that foreign Restricted
         Subsidiary;

                           (xii) El Paso Permitted Liens;

                                       39
<PAGE>

                           (xiii) any Lien upon any additions, improvements,
         replacements, repairs, fixtures, appurtenances or component parts
         thereof attaching to or required to be attached to property or assets
         pursuant to the terms of any mortgage, pledge agreement, security
         agreement or other similar instrument, creating a Lien upon such
         property or assets permitted by clauses (i) through (xii), inclusive,
         of this Section 7.01(ff); or

                           (xiv) any extension, renewal, refinancing, refunding
         or replacement (or successive extensions, renewals, refinancings,
         refundings or replacements) of any Lien, in whole or in part, that is
         referred to in clauses (i) through (xiii), inclusive, of this Section
         7.01(ff) or of any Debt secured thereby; provided, however, that the
         principal amount of Debt secured thereby shall not exceed the greater
         of the principal amount of Debt so secured at the time of such
         extension, renewal, refinancing, refunding or replacement and the
         original principal amount of Debt so secured (plus in each case the
         aggregate amount of premiums, other payments, costs and expenses
         required to be paid or incurred in connection with such extension,
         renewal, refinancing, refunding or replacement); provided, further,
         however, that such extension, renewal, refinancing, refunding or
         replacement shall be limited to all or a part of the property
         (including improvements, alterations and repairs on such property)
         subject to the encumbrance so extended, renewed, refinanced, refunded
         or replaced (plus improvements, alterations and repairs on such
         property).

                  Notwithstanding the foregoing provisions of this Section
7.01(ff), the Guarantor may, and may permit any Restricted Subsidiary to,
create, assume, incur or suffer to exist any Lien upon any Principal Property to
secure any Debt of the Guarantor or any other Person (other than the El Paso
Guarantee) that is not excepted by clauses (i) through (xiv), inclusive, of this
Section 7.01(ff) without securing the El Paso Guarantee, provided that the
aggregate principal amount of all Debt then outstanding secured by such Lien and
all similar Liens, together with all net sale proceeds from Sale-Leaseback
Transactions (excluding Sale-Leaseback Transactions permitted by clauses (i)
through (iv), inclusive, of Section 7.01(gg) below) does not exceed 15% of
Consolidated Net Tangible Assets.

                  (gg) Restriction on Sale-Leaseback Transaction. The Guarantor
shall not, nor shall it permit any Restricted Subsidiary to, engage in a
Sale-Leaseback Transaction, unless:

                           (i) such Sale-Leaseback Transaction occurs within one
         year from the date of acquisition of the Principal Property subject
         thereto or the date of the completion of construction or commencement
         of full operations on such Principal Property, whichever is later;

                           (ii) the Sale-Leaseback Transaction involves a lease
         for a period, including renewals, of not more than three years;

                           (iii) the Guarantor or such Restricted Subsidiary
         would be entitled to incur Debt secured by a Lien on the Principal
         Property subject thereto in a principal amount equal to or exceeding
         the net sale proceeds from such Sale-Leaseback Transaction without
         securing the El Paso Guarantee; or

                           (iv) the Guarantor or such Restricted Subsidiary,
         within a one-year period after such Sale-Leaseback Transaction, applies
         or causes to be applied an amount not less than the net sale proceeds
         from such Sale-Leaseback Transaction to (A) the repayment, redemption
         or retirement of Funded Debt of the Guarantor or any Subsidiary or (B)
         investment in another Principal Property.

                  Notwithstanding the foregoing provisions of this Section
7.01(gg), the Guarantor may, and may permit any Restricted Subsidiary to, effect
any Sale-Leaseback Transaction that is not excepted by clauses (i) through (iv),
inclusive, of this Section 7.01(gg), provided that the net sale proceeds from
such Sale-Leaseback Transaction, together with the aggregate principal amount of
then outstanding Debt

                                       40
<PAGE>

(other than the El Paso Guarantee) secured by Liens upon Principal Properties
not excepted by clauses (i) through (xiv), inclusive, of Section 7.01(ff), do
not exceed 15% of the Consolidated Net Tangible Assets.

                                  ARTICLE VIII

                     LIMITATION ON LIABILITY OF THE ISSUERS

                  SECTION 8.01. Liabilities of the Issuers. The Issuers shall be
liable in accordance herewith only to the extent of the obligations specifically
imposed upon and undertaken by each of them herein.

                                   ARTICLE IX

                                EVENTS OF DEFAULT

                  SECTION 9.01. Events of Default. If one or more of the
following events (herein referred to as "Events of Default") (whatever the
reason for such Events of Default and whether it shall be voluntary or
involuntary or be effected by operation of law or pursuant to any judgment,
decree or order of any court or any order, rule or regulation of any
administrative or governmental body) shall have occurred and be continuing:

                  (a) failure by the Issuers to make (or cause to be made on
their behalf) on any Limestone Note Payment Date a payment of the Limestone
Interest Amount for such Limestone Note Payment Date and such failure continues
for five Business Days;

                  (b) failure by the Issuers to make (or cause to be made on
their behalf) principal payments on the New Limestone Notes when due, whether on
the Maturity Date or any date set for redemption;

                  (c) failure by the Issuers or El Paso duly to observe or to
perform any other covenant of the Issuers or El Paso, as applicable, under the
Closing Agreement, this New Indenture, the New Limestone Notes or the El Paso
Guarantee which failure (i) materially adversely affects the rights of the New
Noteholders and (ii) continues unremedied for a period of 30 days after the
earlier of (A) El Paso or any of its affiliates having actual knowledge of such
default and (B) the giving of written notice of such failure to the Issuers and
El Paso by the New Indenture Trustee or by any New Noteholder;

                  (d) any representation or warranty made by any of Limestone,
the Co-Issuer or El Paso, as applicable, in the Closing Agreement or this New
Indenture or any other document delivered to the New Indenture Trustee pursuant
to this New Indenture shall prove to have been incorrect in any material respect
when made (or deemed made) and such misrepresentation continues to remain
materially incorrect for 30 days after the earlier of (x) El Paso or any of its
affiliates having actual knowledge of such default and (y) the giving of written
notice of such failure to the Issuers and El Paso by the New Indenture Trustee
or by any New Noteholder;

                  (e) this New Indenture, the New Limestone Notes or the Closing
Agreement cease to be the legally valid and enforceable obligation of any of
Limestone, the Co-Issuer or El Paso, which cessation (x) materially adversely
affects the rights of the New Noteholders and (y) continues for 30 days after
the earlier of (A) El Paso or any of its affiliates having actual knowledge
thereof and (B) the giving of written notice of such cessation to the Issuers
and El Paso by the New Indenture Trustee or by any New Noteholder;

                                       41
<PAGE>

                  (f) the El Paso Guarantee shall for any reason cease to be, or
shall be asserted in writing by the Guarantor not to be, in full force and
effect and enforceable in accordance with its terms; provided that if, within
one Business Day after the earlier of (A) El Paso or any of its Affiliates
having actual knowledge of such cessation and (B) the giving of written notice
of such cessation to the Issuers and El Paso by the New Indenture Trustee or by
any New Noteholder, the Guarantor delivers written notice to the New Indenture
Trustee that the Guarantor intends to deliver a valid and effective guarantee
having the same economic effect as the El Paso Guarantee set forth in Article
III, or to reinstate the El Paso Guarantee, as soon as possible, then an Event
of Default shall not exist pursuant to this Section 9.01(f) unless the Guarantor
shall fail to deliver such guarantee or reinstate the El Paso Guarantee within
four Business Days after the delivery of such written notice of the Guarantor's
intent;

                  (g) the rendering of any final money judgment, enforceable in
any competent court, against any of Limestone or the Co-Issuer, and such
judgment shall not be discharged or dismissed or execution thereon stayed within
60 days after entry;

                  (h) the occurrence of any default in the payment when due of
interest on or principal of any El Paso Debt Obligation and such default
continues unremedied for five Business Days after the earlier of (x) El Paso or
any of its affiliates having actual knowledge of such default and (y) the giving
of written notice of such default to the Issuers and El Paso by the New
Indenture Trustee or by any New Noteholder;

                  (i) any of Limestone, the Co-Issuer or El Paso becomes an
investment company required to be registered under the Investment Company Act,
provided that if any such person becomes a transient investment company exempt
from registration pursuant to Rule 3a-2 of the Investment Company Act, it shall
not be an Event of Default;

                  (j) the commencement of any voluntary or involuntary
proceeding seeking liquidation, reorganization or other relief with respect to
any of Limestone, the Co-Issuer or El Paso, and in the case of any such
involuntary proceeding with respect to El Paso, such proceeding has not been
terminated within 60 days after commencement; and

                  (k) the failure by El Paso to make any payment on any (i)
indebtedness for money borrowed by El Paso, (ii) obligation of El Paso (other
than any portion of any trade payable obligation which shall not have remained
unpaid for 91 days or more from the original due date of such portion) to pay
the deferred purchase price of property or services or (iii) obligation of El
Paso as lessee under leases which shall have been or should be, in accordance
with GAAP, recorded as capital leases (it being agreed that for all purposes
hereof, where any such indebtedness or obligation is made jointly, or jointly
and severally, with any third party or parties other than any consolidated
subsidiary, the amount thereof shall be the pro rata portion thereof payable by
El Paso, so long as such third party or parties have not defaulted on its or
their joint and several portions thereof), in each case, when the same becomes
due and payable (whether by scheduled maturity, required prepayment,
acceleration, demand or otherwise) which failure continues after any applicable
grace period, which defaulted payment amount in the aggregate exceeds
$200,000,000 in principal amount;

then, (x) the New Indenture Trustee, at the written direction of the holders of
at least 25% of the aggregate principal amount of the New Limestone Notes
Outstanding in their sole and absolute discretion, shall deliver a written
notice substantially in the form of Exhibit F hereto (a "Default Notice") to the
Issuers and El Paso, which shall specifically state that it is a Default Notice,
(y) the New Indenture Trustee, by notice in writing to the Issuers and El Paso,
shall declare the principal of all the New Limestone Notes and the unpaid
interest accrued thereon to be due and payable immediately, without presentment,
demand, protest or other requirements of any kind, all of which are hereby
expressly waived by the Issuers and the Guarantor, upon (i) in the case of an
Event of Default described in clause (a), (b), (h) or (k), the written direction
of the holders of at least 25% of the aggregate principal amount of the

                                       42
<PAGE>

New Limestone Notes Outstanding and (ii) in the case of any Event of Default
other than an Event of Default described in clause (j) or of the type described
in the immediately preceding clause (i), the written direction of the holders of
at least 50% of the aggregate principal amount of the New Limestone Notes
Outstanding and (z) in the case of an Event of Default described in clause (j),
the principal of all the New Limestone Notes and the unpaid interest accrued
thereon shall automatically become due and payable immediately; provided that
following the occurrence of an Event of Default described in clause (a), such
payment will be at the Optional Redemption Price.

                  SECTION 9.02. Application of Proceeds. Any moneys collected by
the New Indenture Trustee pursuant to this Article, from and after an
Acceleration Date, together with all moneys at the time on deposit in the New
Notes Account, shall be applied in accordance with the provisions of Section
5.04(c) or 5.04(d), as applicable, at the date or dates fixed by the New
Indenture Trustee.

                  SECTION 9.03. Waiver of Past Events of Default. Prior to the
declaration of the acceleration of the New Limestone Notes as provided in
Section 9.01, the Majority New Holders may on behalf of the holders of all the
New Limestone Notes waive any past Indenture Default or Event of Default
hereunder and its consequences, except a default (a) in the payment of principal
of or interest on any of the New Limestone Notes or (b) in respect of a covenant
or provision hereof which cannot be modified or amended without the consent of
the New Holder of each New Limestone Note affected. In the case of any such
waiver, the Issuers, the Guarantor, the New Indenture Trustee and the New
Holders of the New Limestone Notes shall be restored to their former positions
and rights hereunder, respectively, and the relevant Indenture Default or Event
of Default shall cease to exist and be deemed to have been cured and not to have
occurred for every purpose of this New Indenture; but no such waiver shall
extend to any subsequent or other Event of Default or impair any right
consequent thereon.

                  SECTION 9.04. Provisions Relating to Recourse for the Notes.
The New Indenture Trustee shall not take any of the actions described in this
Section 9.04 until the occurrence of an Event of Default and the acceleration of
the New Limestone Notes as a result thereof. Upon the occurrence of an Event of
Default and the acceleration of the New Limestone Notes as a result thereof, the
New Indenture Trustee shall deliver a written notice to the Issuers, El Paso and
the New Noteholders, and the New Limestone Notes will be subject to payment or
redemption in accordance with Section 5.04 and Article XV.

                  (a) [Reserved].

                  (b) [Reserved].

                  (c) New Indenture Trustee's Actions in Event of Proceedings.
Any time the New Indenture Trustee is entitled under this New Indenture to
institute Proceedings to enforce this New Indenture, the New Limestone Notes or
its rights under the other Transaction Documents (other than the Note Purchase
Agreement and the Dealer Manager Agreement) the following shall be applicable:

                           (i) subject to Section 2.05(f), the New Indenture
         Trustee in its own name, and as trustee of an express trust, shall be
         entitled and empowered to institute any Proceedings to recover judgment
         against the Issuers or the Guarantor on this New Indenture, the El Paso
         Guarantee or the New Limestone Notes for the whole amount due and
         unpaid hereunder or thereunder, and may prosecute any such claims or
         Proceedings to judgment or final decree against the Issuers, the
         Guarantor or such other party, and collect the moneys adjudged or
         decreed to be payable in any manner provided by law, whether before or
         after or during the pendency of any Proceedings for the enforcement of
         any of the New Indenture Trustee's rights or the rights of the holders
         under this New Indenture, and such power of the New Indenture Trustee
         shall not be affected by the exercise of any other right, power or
         remedy for the enforcement of the provisions of this New Indenture;

                                       43
<PAGE>

                           (ii) subject to Section 2.05(f) and except as
         required by applicable law or the terms of such judgment or final
         decree, no recovery of any judgment or final decree by the New
         Indenture Trustee and no levy of any execution under any such judgment
         upon any of the Recourse for the Notes shall in any manner or to any
         extent affect the El Paso Guarantee or any rights, powers or remedies
         of the New Indenture Trustee, but the El Paso Guarantee and all such
         rights, powers and remedies shall continue unimpaired as before;

                           (iii) the New Indenture Trustee in its own name, or
         as trustee of an express trust, as the case may be, or in any one or
         more of such capacities shall be entitled and empowered to file such
         proofs of claim and other papers or documents as may be necessary or
         advisable in order to have the claims of the New Indenture Trustee and
         of the New Noteholders (whether such claims be based upon the
         provisions of such New Limestone Notes or of this New Indenture)
         allowed in any receivership, insolvency, bankruptcy, moratorium,
         liquidation, readjustment, reorganization or any other Proceedings
         relative to the Issuers, the Guarantor or the creditors of the Issuers
         or the Guarantor, as the case may be, and any receiver, assignee,
         trustee, liquidator, sequestrator (or other similar official) in any
         such judicial or other proceeding is hereby authorized to make such
         payments to the New Indenture Trustee and, in the event that the New
         Indenture Trustee shall consent to the making of such payments directly
         to the New Noteholders, to pay to the New Indenture Trustee any amount
         due to it for the reasonable compensation, expenses, disbursements and
         advances of the New Indenture Trustee, its agents and counsel;

                           (iv) subject to Section 11.01(b), all rights of
         action and of asserting claims under this New Indenture or under any of
         the New Limestone Notes enforceable by the New Indenture Trustee may be
         enforceable by the New Indenture Trustee to the extent permitted by law
         without possession of any of such New Limestone Notes or the production
         thereof at the trial or other Proceedings relative thereto; and

                           (v) in case the New Indenture Trustee shall have
         proceeded to enforce any right under this New Indenture by suit,
         foreclosure after judgment or otherwise and such Proceedings shall have
         been discontinued or abandoned for any reason, or shall have been
         determined adversely to the New Indenture Trustee, then in every such
         case the Issuers, the Guarantor and the New Indenture Trustee shall, to
         the extent permitted by law, be restored without further act to their
         respective former positions and rights hereunder, and all rights,
         remedies and powers of the New Indenture Trustee shall continue as
         though no such proceedings had been taken, except to the extent
         determined in litigation adversely to the New Indenture Trustee.

                  (d) Waiver of Appraisement, Valuation and Stay. To the extent
they may lawfully do so, the Issuers and the Guarantor for themselves and for
any Person who may claim through or under any of them hereby:

                           (i) agree that neither they nor any such Person will
         plead, claim or in any manner whatsoever take advantage of, any
         appraisement, valuation, stay, extension or redemption laws, now or
         hereafter in force in any jurisdiction, which may delay, prevent or
         otherwise hinder any remedy available with respect to the Recourse for
         the Notes as provided herein or therein; and

                           (ii) waive all benefit or advantage of any such laws.

                  (e) Bankruptcy. In case of the pendency of any receivership,
insolvency, liquidation, bankruptcy, reorganization, arrangement, adjustment,
composition or other Proceeding relative to the Issuers, the Guarantor or the
property of the Issuers, the Guarantor or their respective creditors, the New

                                       44
<PAGE>

Indenture Trustee (irrespective of whether the principal of the New Limestone
Notes shall then be due and payable as herein or therein expressed or by
declaration or otherwise and irrespective of whether the New Indenture Trustee
shall have made any demand on the Issuers or the Guarantor or for the payment of
overdue principal, premium, if any, or interest) shall be entitled and
empowered, by intervention in such Proceeding or otherwise:

                           (i) to file and prove a claim for the whole amount of
         principal, premium, if any, and interest owing and unpaid in respect of
         the New Limestone Notes or in respect of the El Paso Guarantee, as
         applicable, and to file such other papers or documents as may be
         necessary or advisable in order to have the claims of the New Indenture
         Trustee (including any claims for the reasonable compensation,
         expenses, disbursements and advances of the New Indenture Trustee, its
         agents and counsel) and of the New Holders allowed in such Proceeding;
         and

                           (ii) to collect and receive any moneys or other
         property payable or deliverable on any such claims and to distribute
         the same; and any custodian, receiver, assignee, trustee, liquidator,
         sequestrator or similar official in any such Proceeding is hereby
         authorized by each New Holder to make such payments to the New
         Indenture Trustee and, in the event that the New Indenture Trustee
         shall consent to the making of such payments directly to the holders,
         to pay the New Indenture Trustee any amount due it for the reasonable
         compensation, expenses, disbursements and advances of the New Indenture
         Trustee, its agents and counsels, and any other amounts due the New
         Indenture Trustee.

                  Nothing herein contained shall be deemed to authorize the New
Indenture Trustee to authorize or consent to or accept or adopt on behalf of any
New Holder any proposal, plan of reorganization, arrangement, adjustment or
composition or other similar arrangement affecting the New Limestone Notes or
the rights of any New Holder thereof, or to authorize the New Indenture Trustee
to vote in respect of the claim of any holders in any such proceeding.

                  (f) Remedies Cumulative; Delay or Omission Not a Waiver. To
the extent permitted by law, every remedy given hereunder to the New Indenture
Trustee or to any of the New Noteholders shall not be exclusive of any other
remedy or remedies, and every such remedy shall be cumulative and in addition to
every other remedy given hereunder or now or hereafter given by statute, law,
equity or otherwise. The New Indenture Trustee may exercise all or any of the
powers, rights or remedies given to it hereunder or which may be now or
hereafter given by statute, law, equity or otherwise, in its absolute
discretion. No course of dealing between or among the Issuers, the Guarantor
and/or the New Indenture Trustee or the New Noteholders or any delay or omission
of the New Indenture Trustee or of the holders to exercise any right, remedy or
power accruing upon any Event of Default shall impair any right, remedy or power
or shall be construed to be a waiver of any such Event of Default or of any
right of the New Indenture Trustee or of any New Holder or acquiescence therein,
and every right, remedy and power given hereunder to the New Indenture Trustee
or to the New Holders may, to the extent permitted by law, be exercised from
time to time and as often as may be deemed expedient by the New Indenture
Trustee or by the New Holders.

                                    ARTICLE X

     SATISFACTION AND DISCHARGE OF NEW INDENTURE; NOTICE OF CERTAIN EVENTS;
                                UNCLAIMED MONEYS

                  SECTION 10.01. Satisfaction and Discharge of New Indenture. If
at any time (a) the Issuers or the Guarantor shall have paid or caused to be
paid in full the principal of, premium, if any, and interest on, all the New
Limestone Notes Outstanding hereunder or (b) the Issuers shall have delivered to
the New Indenture Trustee for cancellation all New Limestone Notes Outstanding
theretofore

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<PAGE>

authenticated, the New Indenture Trustee, at the reasonable cost and expense of
the Issuers, shall execute proper instruments acknowledging the satisfaction of
and discharging this New Indenture and shall deliver such instruments to El Paso
and the Limestone Trustee. The Issuers and the Guarantor, jointly and severally,
agree to reimburse or cause the reimbursement of the New Indenture Trustee for
any documented costs or expenses thereafter reasonably and properly incurred and
to compensate the New Indenture Trustee for any services thereafter reasonably
and properly rendered by the New Indenture Trustee in connection with this New
Indenture or the New Limestone Notes.

                  SECTION 10.02. Reserved.

                  SECTION 10.03. Repayment of Moneys and Transfer of Eligible
Investments Held by New Indenture Trustee. Following the satisfaction and
discharge of this New Indenture, all moneys and Financial Investments then held
by the New Indenture Trustee under the provisions of this New Indenture
(including all moneys and Financial Investments then held in the New Notes
Account) shall be promptly repaid or, as the case may be, assigned or
transferred to the Issuers, and thereupon the New Indenture Trustee shall be
released from all further liability with respect to such moneys and such
Financial Investments.

                  SECTION 10.04. Return of Moneys Held by New Indenture Trustee.
Any moneys deposited with or paid to the New Indenture Trustee or any Paying
Agent in trust for the payment of the principal of, premium, if any, or interest
on any New Limestone Note and not applied but remaining unclaimed for two years
after the date upon which such principal, premium, if any or interest shall have
become due and payable shall be repaid to or for the account of the Limestone
Trustee, the receipt of such repayment to be confirmed promptly in writing by or
on behalf of the Limestone Trustee, and, to the extent permitted by law, the New
Holder of such New Limestone Note shall thereafter look only to the Issuers for
any payment which such New Holder may be entitled to collect, and all liability
of the New Indenture Trustee with respect to such moneys shall thereupon cease.

                                   ARTICLE XI

                      CONCERNING THE NEW INDENTURE TRUSTEE

                  SECTION 11.01. Duties of the New Indenture Trustee; Certain
Rights of the New Indenture Trustee.

                  (a) The Bank of New York agrees to act, and is hereby
appointed by the Issuers, to act as the New Indenture Trustee under this New
Indenture. The New Indenture Trustee is hereby authorized and empowered after
the acceleration of the New Limestone Notes in accordance with this New
Indenture and to the extent permitted under and in compliance with applicable
law and regulations, to commence enforcement proceedings with respect to such
Recourse for the Notes.

                  (b) The New Indenture Trustee undertakes to perform such
duties and only such duties as are specifically set forth in this New Indenture
and the other Transaction Documents to which it is a party and no implied duties
shall be read into this New Indenture or the other Transaction Documents.
Neither the New Indenture Trustee, its agents nor Affiliates shall be liable for
any act or omission made in connection with this New Indenture or the other
Transaction Documents except in the case of its gross negligence, bad faith or
willful misconduct. In furtherance, and not in limitation, of the New Indenture
Trustee's rights, duties and protections hereunder, and unless otherwise
specifically provided in this New Indenture, the New Indenture Trustee shall
(subject to the terms hereof and of the other Transaction Documents) grant such
consents, make such requests and determinations and take or refrain from taking
such actions (including, without limitation, actions with respect to an Event of
Default, of which the New Indenture Trustee has notice) as are permitted (but
not expressly required) to be granted, made or taken by

                                       46
<PAGE>

the New Indenture Trustee under the Transaction Documents, as the Majority New
Holders shall direct in writing. No provision of this New Indenture shall be
construed to relieve the New Indenture Trustee from liability for its own
grossly negligent action, its own grossly negligent failure to act or its own
misconduct, its grossly negligent failure to perform its obligations in
compliance with this New Indenture, or any liability which would be imposed by
reason of its willful misfeasance or bad faith; provided, however, that:

                           (i) the duties and obligations of the New Indenture
         Trustee shall be determined solely by the express provisions of this
         New Indenture, the New Indenture Trustee shall not be personally liable
         except for the performance of such duties and obligations as are
         specifically set forth in this New Indenture, no implied covenants,
         duties or obligations shall be read into this New Indenture against the
         New Indenture Trustee and the New Indenture Trustee may conclusively
         rely, as to the truth of the statements and the correctness of the
         opinions expressed therein, upon any certificates or opinions furnished
         to the New Indenture Trustee and conforming to the requirements of this
         New Indenture which it reasonably believes in good faith to be genuine
         and to have been duly executed by the proper authorities respecting any
         matters arising hereunder;

                           (ii) the New Indenture Trustee shall not be
         personally liable for an error of judgment made in good faith by a
         Responsible Officer or Responsible Officers of the New Indenture
         Trustee, unless the New Indenture Trustee was grossly negligent or
         acted in bad faith or with willful misfeasance;

                           (iii) the New Indenture Trustee shall not be
         personally liable with respect to any action taken, suffered or omitted
         to be taken by it in good faith in accordance with the direction of the
         Majority New Noteholder or the Issuers, relating to the time, method
         and place of conducting any proceeding for any remedy available to the
         New Indenture Trustee, or exercising any trust or power conferred upon
         the New Indenture Trustee, under this New Indenture; and

                           (iv) no provision of this New Indenture or the other
         Transaction Documents shall require the New Indenture Trustee to expend
         or risk its own funds or otherwise incur any financial liability in the
         performance of any of its duties hereunder or in the exercise of any of
         its rights or powers if it shall have reasonable grounds for believing
         that repayment of such funds or adequate indemnity against such risk or
         liability is not reasonably assured to it.

                  (c) Certain Rights of New Indenture Trustee.

                           (i) The New Indenture Trustee may request and rely
         upon, and shall be protected in acting or refraining from acting upon,
         and shall not be bound to make any investigation into the facts or
         matters stated in, any resolution, certificate, statement, instrument,
         opinion, report, notice, request, consent, order, note, guaranty or
         other paper or document believed by it to be genuine and to have been
         signed or presented by the proper party or parties, but the New
         Indenture Trustee in its sole discretion may make such further inquiry
         or investigation into such facts or matters as it may see fit;

                           (ii) The New Indenture Trustee shall be under no
         obligation to exercise any of the rights or powers vested in it by this
         New Indenture or any of the other Transaction Documents at the request,
         order or direction of any of the New Holders, including the Majority
         New Holders, pursuant to the provisions of this New Indenture or any of
         the other Transaction Documents, unless (A) such request, order or
         direction shall not be in conflict with any Applicable Law or this New
         Indenture or expose the New Indenture Trustee to any personal liability
         for which it is not, in its sole discretion, adequately indemnified and
         (B) such New Holders or other entities shall have furnished to the New
         Indenture Trustee reasonable security or indemnity (including

                                       47
<PAGE>

         reasonable advances) against the costs, expenses and liabilities
         (including, without limitation, attorneys' fees and expenses) which
         might be incurred therein or thereby;

                           (iii) None of the provisions contained in this New
         Indenture shall require the New Indenture Trustee to expend or risk its
         own funds or otherwise incur personal financial liability in the
         performance of any of its duties or in the exercise of any of its
         rights or powers;

                           (iv) As a condition to the taking or omitting of any
         action by it hereunder, the New Indenture Trustee may consult with
         counsel, accountants or other experts and the advice of such counsel,
         accountants or other experts or any Opinion of Counsel shall be full
         and complete authorization and protection in respect of any action
         taken or omitted by it hereunder in good faith and in reliance thereon;

                           (v) For all purposes under this New Indenture, the
         New Indenture Trustee shall not be deemed to have notice or knowledge
         of any Indenture Default, Event of Default or Specified Equity Event
         (other than the Events of Default specified in Section 9.01(a) and (b))
         unless a Responsible Officer of the New Indenture Trustee assigned to
         and working in the Corporate Trust Office has actual knowledge thereof
         or unless written notice of such an Indenture Default, Event of Default
         or Specified Equity Event is received by the New Indenture Trustee at
         the Corporate Trust Office and such notice references the New Limestone
         Notes generally, the Issuers, the El Paso Guarantee or this New
         Indenture; and

                           (vi) In no event shall the New Indenture Trustee be
         liable for the selection of investments or of investment losses
         incurred thereon. The New Indenture Trustee shall have no liability in
         respect of losses incurred as a result of the liquidation of any
         investment prior to its stated maturity.

                  (d) In the event that the New Indenture Trustee is also acting
         as Paying Agent and/or Registrar hereunder, the rights and protection
         afforded to the New Indenture Trustee pursuant to this Article XI shall
         also be afforded to such Paying Agent and/or Registrar.

                  SECTION 11.02. Performance of New Indenture Trustee's Duties.

                  (a) Neither the New Indenture Trustee nor its agents shall be
liable to any Person for any delay in or failure of payment or for any
nonperformance or default on the part of any party (other than the New Indenture
Trustee) under the Transaction Documents.

                  (b) Subject to Section 2.05(f), the New Indenture Trustee may,
in the execution and exercise of all or any of the trusts, powers, authorities
and discretions vested in it by the Transaction Documents, act by Responsible
Officers or a Responsible Officer of the New Indenture Trustee or its
Affiliates, and the New Indenture Trustee may also whenever it deems it
expedient in the interests of the New Noteholders, whether by power of attorney
or otherwise, delegate to any Person or fluctuating body of Persons all or any
of the trusts, powers, authorities and discretions vested in it by the
Transaction Documents and any such delegation may be made upon such terms and
conditions and subject to such regulations (including power to subdelegate) as
the New Indenture Trustee may deem fit and it shall not in any way or to any
extent be responsible for any loss incurred by any misconduct or default on the
part of such delegate or subdelegate; provided that the New Indenture Trustee
shall exercise reasonable care in the selection of such delegate and, subject to
Section 11.03, shall continue to be responsible for the execution and exercise
of all or any of the trusts, powers, authorities and discretions vested in it by
the Transaction Documents. The New Indenture Trustee shall give prompt notice to
the Issuers and El Paso of the appointment (and termination thereof) of any
delegate as aforesaid and shall procure that any delegate shall also give prompt
notice to the Issuers and El Paso of any subdelegate.

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<PAGE>

                  (c) Neither the New Indenture Trustee nor any director or
officer of the New Indenture Trustee shall be precluded from underwriting,
guaranteeing the subscription of or subscribing for some or all of the New
Limestone Notes with or without a commission or other remuneration or from
purchasing or otherwise acquiring, holding, dealing in or disposing of the New
Limestone Notes or any of them or any notes, bonds, debentures, debenture stock,
shares or securities whatsoever of, or from acting as banker (including, without
limitation, engaging in normal banking, trust and investment banking business),
paying agent or process agent for or with, the Issuer and any Affiliate thereof
or from otherwise at any time contracting or entering into any financial or
other transactions with the Issuers or any Affiliate thereof or from accepting
and holding the office of indenture trustee for the holders of any securities of
the Issuers or any Affiliate thereof.

                  SECTION 11.03. Resignation and Removal; Appointment of
Successor New Indenture Trustee.

                  (a) The New Indenture Trustee (i) may resign and be discharged
of the trust created by this New Indenture by giving 30 days' written notice to
the Issuers, the New Holders and the Guarantor and (ii) shall resign if it fails
to meet the requirements of Section 11.09, and such resignation shall take
effect upon receipt by the New Indenture Trustee of an instrument of acceptance
of appointment executed by a successor New Indenture Trustee as herein provided
in Section 11.04.

                  (b) The New Indenture Trustee may be removed for cause upon
written notice by the Majority New Holders delivered to the New Indenture
Trustee, the Issuers and El Paso.

                  (c) If at any time the New Indenture Trustee shall resign or
be removed or otherwise become incapable of acting, or if at any time a vacancy
shall occur in the office of the New Indenture Trustee for any other cause,
Limestone shall use its best efforts to locate and recommend a qualified
successor New Indenture Trustee or New Indenture Trustees and a successor New
Indenture Trustee or New Indenture Trustees may be appointed by Limestone
(whether or not such successor or successors shall have been located or
recommended by Limestone) upon written notice to the New Noteholders and the New
Indenture Trustee. In the event that no such successor New Indenture Trustee (or
New Indenture Trustees) is appointed by Limestone within 30 days after the
giving of a notice of resignation, the New Indenture Trustee may request a court
to make such appointment. Every successor New Indenture Trustee appointed
pursuant to this Section 11.03 shall be a corporation or association organized
under the law of the United States or any State thereof having a corporate trust
department and a combined capital and surplus of at least $150,000,000 and a
long-term debt rating of at least "A3" by Moody's and at least "A-" by S&P and
Fitch and otherwise satisfying the criteria set forth in Section 11.09, if there
be such an institution willing and able to accept the trust upon reasonable or
customary terms.

                  SECTION 11.04. Acceptance of Appointment by Successor New
Indenture Trustee. Any successor New Indenture Trustee appointed as provided in
Section 11.03 shall execute, acknowledge and deliver to the Issuers and to its
predecessor New Indenture Trustee an instrument accepting such appointment
hereunder, and, subject to the provisions of Section 11.03, thereupon the
resignation or removal of the predecessor New Indenture Trustee shall become
effective and such successor New Indenture Trustee, without any further act,
deed or conveyance, shall become vested with all the rights, powers, duties and
obligations of its predecessor hereunder, with like effect as if originally
named as New Indenture Trustee herein; but, nevertheless, at the written
direction of the Majority New Holders or written request of the successor New
Indenture Trustee, the New Indenture Trustee ceasing to act shall execute and
deliver an instrument transferring to such successor New Indenture Trustee all
the rights and powers of the New Indenture Trustee so ceasing to act.

                  SECTION 11.05. Merger or Consolidation of New Indenture
Trustee. Any corporation into which the New Indenture Trustee may be merged or
converted or with which it may be consolidated or any corporation resulting from
any merger, conversion or consolidation to which the New Indenture

                                       49
<PAGE>

Trustee shall be a party shall be the successor of the New Indenture Trustee
hereunder; provided that such corporation shall be qualified under the
provisions of Section 11.03(c), without the execution or filing of any paper or
any further act on the part of any of the parties hereto or the holders,
notwithstanding anything contained herein to the contrary.

                  SECTION 11.06. Certain Procedural Matters. Subject to Sections
2.05(f) and 13.01, the New Indenture Trustee, in its own name and as New
Indenture Trustee of an express trust, at the written direction of the Majority
New Holders, shall be entitled and empowered to institute any Proceeding for the
collection of any amounts due and unpaid or the enforcement of any other rights
of the holders and prosecute any such action or proceeding to judgment or final
decree.

                  SECTION 11.07. New Indenture Trustee Fees and Indemnification.

                  (a) The Issuers and the Guarantor, jointly and severally,
covenant and agree to pay or reimburse the New Indenture Trustee upon its
request for the New Indenture Trustee Fee and the documented expenses,
disbursements and advances reasonably and properly incurred or made by the New
Indenture Trustee in accordance with any of the provisions of this New Indenture
(including the reasonable compensation and the expenses and disbursements of its
counsel and of all Persons not regularly in its employ, whether or not such
expenses are incurred in connection with any Opinion of Counsel required or
permitted to be obtained by the New Indenture Trustee) ("New Indenture Trustee
Expenses"), except that the Issuers and the Guarantor shall not pay or reimburse
the New Indenture Trustee for any expense, disbursement or advance as may arise
from the gross negligence, willful misfeasance or bad faith of the New Indenture
Trustee or the Person to be indemnified. The New Indenture Trustee agrees that
all New Indenture Trustee Fees and New Indenture Trustee Expenses are for the
account of the Issuers and the Guarantor, and it shall have no Lien or claim on
the Recourse for the Notes in respect thereof. The New Indenture Trustee and any
director, officer, employee or agent of the New Indenture Trustee shall be
indemnified by the Issuers and the Guarantor, jointly and severally, and held
harmless against any loss, liability, claim or expense incurred in connection
with any legal action or claim, including any pending or threatened legal action
or claim, relating to this New Indenture or the New Limestone Notes, or the
performance of any of the New Indenture Trustee's duties hereunder, other than
any loss, liability, claim or expense incurred by reason of willful misfeasance,
bad faith or gross negligence in the performance of duties hereunder or by
reason of reckless disregard of obligations and duties hereunder; provided that
(i) with respect to any such legal action the New Indenture Trustee shall have
given the Issuers and the Guarantor notice thereof promptly after the New
Indenture Trustee shall have knowledge thereof and (ii) the Issuers and the
Guarantor shall defend such legal action and the New Indenture Trustee shall
cooperate and consult fully with the Issuers and the Guarantor in preparing such
defense; provided, further, however, that any failure to notify the Issuers and
the Guarantor of such legal action shall not diminish the obligations of the
Issuers and the Guarantor hereunder. Such indemnity shall survive the
termination or discharge of this New Indenture and the resignation or removal of
the New Indenture Trustee. Any payment in respect of the New Indenture Trustee
Fee, New Indenture Trustee Expenses or the foregoing indemnity made by the
Issuers and/or the Guarantor to the New Indenture Trustee shall be from the
Issuers' and/or the Guarantor's own funds, without reimbursement from the
Recourse for the Notes therefor.

                  (b) The New Indenture Trustee shall be required to pay all
expenses, except as expressly provided herein, incurred by it or its agents in
connection with its activities hereunder and shall be entitled to reimbursement
therefor as provided in this Section 11.07. The New Indenture Trustee shall in
no event acquire any claim against the New Noteholders, the Issuers or the
Guarantor by reason of non-receipt of any fees and expenses and the New
Indenture Trustee shall, unless and until the effective date of any resignation
of the New Indenture Trustee under Section 11.03, continue to perform its
obligations hereunder notwithstanding such non-receipt. When the New Indenture
Trustee incurs expenses or renders services in connection with an Event of
Default described in Section 9.01(j), such expenses (including the fees and
expenses of its counsel and agents) and the compensation for such

                                       50
<PAGE>

services are intended to constitute expenses of administration under any
bankruptcy law or law relating to creditors' rights generally.

                  SECTION 11.08. Information. The New Indenture Trustee will
promptly deliver to the New Noteholders, the Rating Agencies and El Paso any
notices, including notices of Events of Default, financial statements, officer's
certificates or other forms of communication that it receives pursuant to the
terms of this New Indenture.

                  SECTION 11.09. Eligibility Requirements for New Indenture
Trustee. The New Indenture Trustee hereunder shall at all times be a corporation
or association having a corporate trust office in the State of Delaware or New
York and organized and doing business under the laws of such state or the United
States of America, authorized under such laws to exercise corporate trust powers
(i) having a combined capital and surplus of at least $150,000,000, (ii) having
a long-term debt rating of at least "A3" by Moody's and at least "A-" by S&P and
Fitch and (iii) shall be subject to supervision or examination by federal or
state authority. If such corporation or association publishes reports of
condition at least annually, pursuant to law or to the requirements of the
aforesaid supervising or examining authority, then for the purposes of this
Section 11.09 the combined capital and surplus of such corporation or
association shall be deemed to be its combined capital and surplus as set forth
in its most recent report of condition so published. In case at any time the New
Indenture Trustee shall cease to be eligible in accordance with the provisions
of this Section 11.09, the New Indenture Trustee shall resign immediately in the
manner and with the effect specified in Section 11.03.

                  SECTION 11.10. New Indenture Trustee Not Liable for New
Limestone Notes. The recitals contained herein shall be taken as the statements
of the Issuers and the New Indenture Trustee assumes no responsibility for their
correctness. Except for the Certificate of Authentication on the New Limestone
Notes, the New Indenture Trustee makes no representations as to the validity or
sufficiency of the New Limestone Notes or any related Transaction Documents. The
New Indenture Trustee shall be responsible for any funds that may be deposited
with it pursuant to Section 5.02 and for payment of amounts deposited therein in
accordance with Section 5.04. The New Indenture Trustee shall have no duty to
monitor the performance of the Issuers, nor shall it have any liability in
connection with the malfeasance or nonfeasance by the Issuers. The New Indenture
Trustee shall have no liability in connection with compliance by the Issuers
with statutory or regulatory requirements related to the Transaction Documents
or any related instrument or agreement.

                  SECTION 11.11. New Indenture Trustee May Own New Limestone
Notes. The Bank of New York, in its capacity as the New Indenture Trustee, in
its individual or any other capacity, and any of its Affiliates may become the
owner or pledgee of New Limestone Notes with the same rights as it would have if
it were not the New Indenture Trustee.

                  SECTION 11.12. Maintenance of Office or Agency. The New
Indenture Trustee will maintain or cause to be maintained at its expense an
office or offices or agency or agencies where New Limestone Notes may be
surrendered for payment, registration of transfer or exchange and where notices
and demands to or upon the New Indenture Trustee in respect of the New Limestone
Notes and this New Indenture may be served. The New Indenture Trustee will give
prompt written notice to the New Noteholders of any change in the location of
the Note Register or any such office or agency.

                  SECTION 11.13. Appointment of Co-Indenture Trustee. The New
Indenture Trustee, with the consent of the Issuers and only for the purpose of
meeting the legal requirements, if any, of certain jurisdictions, shall have the
power to appoint co-indenture trustees. In the event of such appointment, all
rights, powers and duties and obligations conferred or imposed upon the New
Indenture Trustee by this New Indenture will be conferred or imposed upon the
co-indenture trustee and such co-indenture trustee jointly, or in any
jurisdiction where the New Indenture Trustee is incompetent or

                                       51
<PAGE>

unqualified to perform certain acts, singly shall exercise and perform such
rights, powers, duties and obligations solely at the discretion of the New
Indenture Trustee.

                  SECTION 11.14. [Reserved].

                  SECTION 11.15. [Reserved].

                  SECTION 11.16. [Reserved].

                                   ARTICLE XII

                           SUPPLEMENTAL NEW INDENTURES

                  SECTION 12.01. Supplemental New Indentures Without Consent of
New Noteholders. The Issuers, the Guarantor and the New Indenture Trustee may
from time to time and at any time enter into an indenture or indentures
supplemental hereto for one or more of the following purposes:

                  (a) to cure any ambiguity or to correct or supplement any
provision contained herein, in the New Limestone Notes or the El Paso Guarantee
or in any supplemental indenture which may be defective or inconsistent with any
other provision contained herein or in the New Limestone Notes or in any
supplemental indenture;

                  (b) to make such other provisions in regard to matters or
questions arising under this New Indenture, the New Limestone Notes or the El
Paso Guarantee or under any supplemental indenture as the Issuers, the Guarantor
and the New Indenture Trustee may deem necessary or desirable and which shall
not adversely affect the rights or obligations of the New Noteholders;

                  (c) to secure the El Paso Guarantee pursuant to the
requirements of Section 7.01(ff) or otherwise;

                  (d) in accordance with Section 7.01(dd) only, to evidence the
succession of another Person to the Guarantor and the assumption by any such
successor of the covenants of the Guarantor herein, in the New Limestone Notes
and in the El Paso Guarantee; or

                  (e) to add to the covenants of the Guarantor or the Events of
Default relating to the Guarantor for the benefit of the holders of the New
Limestone Notes or to surrender any right or power herein conferred upon the
Guarantor other than such rights or powers conferred upon the Guarantor pursuant
to Section 3.08 and Section 3.09.

                  The New Indenture Trustee is hereby authorized to join in the
execution of any such supplemental indenture and to make any further appropriate
agreements and stipulations which may be therein contained, but the New
Indenture Trustee shall not be obligated to enter into any such supplemental
indenture which affects the New Indenture Trustee's own rights, duties or
immunities under this New Indenture or under the other Transaction Documents or
otherwise.

                  Any supplemental indenture authorized by the provisions of
this Section may be executed without the consent of the holders of any of the
New Limestone Notes at the time Outstanding, notwithstanding any of the
provisions of Section 12.02.

                  SECTION 12.02. Supplemental New Indentures With Consent of New
Noteholders. With the consent (evidenced as provided in Article XIII) of the
Majority New Holders, the Issuers, the Guarantor and the New Indenture Trustee
may, from time to time and at any time, enter into an indenture or indentures
supplemental hereto for the purpose of adding any provisions to or changing in
any manner

                                       52
<PAGE>

or eliminating any of the provisions of this New Indenture, the New Limestone
Notes or the El Paso Guarantee endorsed thereon or of any supplemental indenture
or of modifying in any manner the rights of the holders of the New Limestone
Notes; provided that no such supplemental indenture shall (a) extend the final
maturity of any New Limestone Note or the time of payment of any principal
thereof, or reduce the principal amount thereof, or any premium thereon or
extend the time of payment of any interest thereon, or reduce any amount payable
on redemption thereof or reduce the amount of principal that would be due and
payable upon the occurrence of an Event of Default, or impair or affect the
rights of any New Noteholder to institute suit for the payment thereof, (b)
increase or decrease the Limestone Note Rate, (c) reduce any amount required to
be collected or retained in the New Notes Account, (d) reduce the aforesaid
percentage of New Limestone Notes the consent of the New Holders of which is
required for any supplemental indenture or (e) release the Guarantor from its
obligations under the El Paso Guarantee, other than in accordance with this New
Indenture, in each case without the consent of the holders of each New Limestone
Note so affected.

                  Upon the request of the Issuers, accompanied by a copy of the
supplemental indenture and upon the filing with the New Indenture Trustee of
evidence of the consent of the Majority New Holders or any greater percentage of
New Holders as required by this Section 12.02 and other documents, if any,
required by this Section 12.02, the New Indenture Trustee shall join with the
Issuers and the Guarantor in the execution of such supplemental indenture unless
such supplemental indenture affects the New Indenture Trustee's own rights,
duties or immunities under this New Indenture or otherwise, in which case the
New Indenture Trustee may in its discretion, but shall not be obligated to,
enter into such supplemental indenture.

                  It shall not be necessary for the consent of the New
Noteholders under this Section to approve the particular form of any proposed
supplemental indenture, but it shall be sufficient if such consent shall approve
the substance thereof.

                  SECTION 12.03. Effect of Supplemental New Indenture. Upon the
execution of any supplemental indenture pursuant to the provisions hereof, this
New Indenture and the New Limestone Notes (including the El Paso Guarantee
endorsed thereon) shall be and be deemed to be modified and amended in
accordance therewith and the respective rights, limitations of rights,
obligations, duties and immunities under this New Indenture of the New Indenture
Trustee, the Issuers, the Guarantor and the New Noteholders shall thereafter be
determined, exercised and enforced hereunder subject in all respects to such
modifications and amendments, and all the terms and conditions of any such
supplemental indenture shall be and be deemed to be part of the terms and
conditions of this New Indenture for any and all purposes.

                  SECTION 12.04. Documents to Be Given to New Indenture Trustee.
The New Indenture Trustee, subject to the provisions of Sections 12.01 and
12.02, shall be entitled to receive one or more Officer's Certificate or
Certificates and Opinion or Opinions of Counsel as conclusive evidence that any
such supplemental indenture complies with the applicable provisions of this New
Indenture.

                  SECTION 12.05. Notation on New Limestone Notes in Respect of
Supplemental New Indentures. New Limestone Notes (including the El Paso
Guarantee endorsed thereon) authenticated and delivered after the execution of
any supplemental indenture pursuant to the provisions of this Article may bear a
notation in form and manner approved by the New Indenture Trustee as to any
matter provided for by such supplemental indenture. If the Issuers shall so
determine, new New Limestone Notes (including the El Paso Guarantee endorsed
thereon) so modified as to conform to any modification of this New Indenture
contained in any such supplemental indenture may be prepared by the Issuers at
their expense, authenticated by the New Indenture Trustee and delivered in
exchange for the New Limestone Notes then Outstanding.

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                                  ARTICLE XIII

                           CONCERNING THE NEW HOLDERS

                  SECTION 13.01. Control by Majority New Holders. Subject to the
provisions of Section 2.05(f), the Majority New Noteholders shall have the right
to direct the New Indenture Trustee, in writing, to direct the time, method, and
place of conducting any proceeding for any remedy available to the New Indenture
Trustee or exercising any trust or power conferred on the New Indenture Trustee;
provided that to the extent that both (i) the Noteholders and/or the
Certificateholders and (ii) the New Noteholders have given directions with
respect to the Asset Remedy or in the case of the New Noteholders, asset sales
in accordance with Section 2.05(f) of this New Indenture, the directions given
by the Noteholders or the Certificateholders (as determined pursuant to the
Indenture) shall govern; provided, further, that:

                  (a) the New Indenture Trustee shall not be required to act if
the New Indenture Trustee shall have received an Opinion of Counsel that the
action so directed may not lawfully be taken or would be in conflict with this
New Indenture;

                  (b) if the payment within a reasonable time to the New
Indenture Trustee of the reasonable costs, expenses or liabilities likely to be
incurred by it in the taking, suffering or omission of such action, in the
reasonable opinion of the New Indenture Trustee, is not assured to the New
Indenture Trustee by the terms of this New Indenture, the New Indenture Trustee
may require reasonable security or indemnity (including reasonable advances)
against any such expense or liability as a condition to the taking, suffering or
omission of any such action; and

                  (c) the New Indenture Trustee may take any other reasonable
action deemed proper by the New Indenture Trustee that is consistent with such
direction; provided, however, that subject to Section 11.01, the New Indenture
Trustee need not take any action that is discretionary or that it determines
might impose liability on the New Indenture Trustee for which it is not, in its
sole discretion, adequately indemnified.

                  SECTION 13.02. Evidence of Action Taken by New Holders.
Whenever in this New Indenture or in any other Transaction Document it is
provided that the Majority New Holders may take any action (including the making
of any demand or request, the giving of any notice, direction, instruction,
consent or waiver or the taking of any other action), the fact that at the time
of taking any such action the Majority New Holders have joined therein shall be
evidenced in writing by one or more instruments of similar tenor executed by
such New Holders in person or by agent or proxy appointed in writing. Such
action by the Majority New Holders shall become effective when such instrument
or instruments are delivered to and received by the New Indenture Trustee. The
New Indenture Trustee shall thereafter notify the Issuers and El Paso of the
effectiveness of such action.

                  SECTION 13.03. Proof of Execution of Instruments. The fact and
date of the execution of any instrument by a New Holder or his agent or proxy
may be proved by the certificate of any notary public or other officer of any
jurisdiction within or without the United States authorized to take
acknowledgments of deeds to be recorded in such jurisdiction that the person
executing such instrument acknowledged to him the execution thereof, or by an
affidavit of a witness to such execution sworn to before any such notary or
other such officer. Where such execution is by or on behalf of any legal entity
other than an individual, such certificate or affidavit shall also constitute
proof of the authority of the individual executing the same.

                  SECTION 13.04. New Limestone Notes Owned by the Issuers. In
determining whether the holders have concurred in any direction, request,
consent or waiver under this New Indenture, New Limestone Notes which are owned
by the Issuers, El Paso or any of their respective

                                       54
<PAGE>

Affiliates thereof shall be disregarded in both the numerator and denominator of
the fraction used to determine the requisite percentage.

                  SECTION 13.05. Right of Revocation of Action Taken. At any
time prior to (but not later than) the evidencing to the New Indenture Trustee,
as provided in Section 13.02, of the taking of any action by the holders, any
New Holder of a New Limestone Note the serial number of which is shown by the
evidence to be included in those New Limestone Notes the holders of which have
consented to such action may, by filing written notice with the New Indenture
Trustee at the Corporate Trust Office and upon proof of holding as provided in
Section 2.05, revoke such action insofar as it concerns such New Limestone Note.
Unless revoked pursuant to the foregoing provisions, any such action taken by a
New Holder shall be conclusive and binding upon such New Holder and upon all
future holders and owners of such New Limestone Note and of any New Limestone
Note issued in exchange or substitution therefor, irrespective of whether or not
any notation in regard thereto is made upon such New Limestone Note. Except as
otherwise provided herein, any action taken by the Majority New Holders shall be
conclusive and binding upon the Issuers, the Guarantor, the New Indenture
Trustee and the holders of all New Limestone Notes.

                                   ARTICLE XIV

                               OPTIONAL REDEMPTION

                  SECTION 14.01. Optional Redemption.

                  (a) So long as the maturity of the New Limestone Notes has not
been accelerated as a result of an Event of Default, the New Limestone Notes:

                           (i) may be redeemed in whole or in part at the option
                  of the Issuers at any time, and

                           (ii) may be redeemed by the Issuers in whole or in
                  part at the option of the Issuers to the extent of funds
                  available therefor (provided that, if El Paso Chaparral elects
                  to exercise the Purchase Option or Retirement Option, the New
                  Limestone Notes may be redeemed by the Issuers pursuant to
                  clause (B) below in whole and not in part) if any one or more
                  of the following occurs:

                                    (A) the Guarantor causes funds to be
                  irrevocably deposited with the New Indenture Trustee, pursuant
                  to Section 3.09, to be used to cause an Optional Redemption,
                  or

                                    (B) the Indenture Trustee or Limestone, as
                  the case may be, distributes funds to be irrevocably deposited
                  with the New Indenture Trustee to be used to cause an Optional
                  Redemption.

         In each case described in clause (ii), the Issuers shall exercise their
         option and redeem the New Limestone Notes to the extent of the amounts
         deposited with the New Indenture Trustee (subject to Section 14.01(c)),
         unless holders of not less than 51% of the face amount of outstanding
         Limestone Certificates shall have elected to cause the funds so
         deposited to be invested in eligible Financial Investments having
         maturities that coincide with required payments on the New Limestone
         Notes; provided that if the funds so deposited are not sufficient to
         purchase Financial Investments the payments on which are sufficient to
         cover the required payments on the New Limestone Notes, the Limestone
         Certificateholders shall be entitled to make the election described in
         this Section 14.01(a) only if they deposit or cause to be deposited
         with the New

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<PAGE>

         Indenture Trustee the amounts necessary such that the total amount
         deposited with the New Indenture Trustee and invested in such eligible
         Financial Investments are sufficient to purchase Financial Investments
         the payments on which are sufficient to cover the required payments on
         the New Limestone Notes; provided further that if the
         Certificateholders make such election, none of the Guarantor, the
         Issuers, the New Indenture Trustee or the Indenture Trustee shall have
         any further obligations under this Section 14.01(a).

                  (b) Any such redemption of the New Limestone Notes (an
"Optional Redemption") may be made in whole or in part (or in whole but not in
part if the Primary Class B Member elects to exercise the Purchase Option or
Retirement Option) in minimum denominations of $100,000 and integral multiples
of $1,000 in excess thereof on any Business Day specified in the applicable
Notice of Optional Redemption; provided that in the case of an Optional
Redemption pursuant to Section 14.01(a)(ii)(B) arising from the Primary Class B
Member electing to exercise the Purchase Option or Retirement Option, such date
shall be the Retirement Date or Purchase Date, as applicable, set forth in the
Retirement Notice or Purchase Option Notice, as applicable, delivered to the
Indenture Trustee and/or Limestone pursuant to the Chaparral LLC Agreement (any
such date, the "Optional Redemption Date") at the Optional Redemption Price.

                  (c) Any Optional Redemption pursuant to Section 14.01(a) shall
occur at such time as (i) the New Indenture Trustee shall have received written
notice from the Indenture Trustee, the Limestone Trustee or the Guarantor, as
applicable, specifying that the amounts deposited into the New Notes Account are
to be used to cause an Optional Redemption, (ii) the aggregate amount of funds
irrevocably deposited with the New Indenture Trustee is sufficient to effect
such redemption and (iii) appropriate notice is given in accordance with Section
14.02.

                  (d) [Reserved].

                  (e) The "Optional Redemption Price" for each New Limestone
Note redeemed on any Optional Redemption Date will be equal to the sum of: (i)
accrued and unpaid interest (including Default Interest, if any) on the
principal amount to be prepaid to the Optional Redemption Date and (ii) the
greater of: (a) 100% of the outstanding principal amount of such New Limestone
Note (or the portion thereof being prepaid) and (b) the sum of the present
values of the remaining scheduled payments of principal (or the portion thereof
being prepaid) and interest thereon (without duplication of interest paid in
clause (i)) discounted to the Optional Redemption Date on a semi-annual basis
(assuming a 360-day year consisting of twelve 30-day months) at the applicable
Treasury Yield plus 50 basis points.

                  SECTION 14.02. Notice of Optional Redemption. Notice of an
Optional Redemption (a "Notice of Optional Redemption") of the New Limestone
Notes pursuant to Section 14.01 shall be given by the Issuers or, at the
Issuers' request, by the New Indenture Trustee, if the Issuers shall have
delivered to the New Indenture Trustee, at least 45 days prior to the Optional
Redemption Date (or such lesser number of days as shall be acceptable to the New
Indenture Trustee), an Issuers' Certificate requesting that the New Indenture
Trustee give a Notice of Optional Redemption. In the case of an Optional
Redemption pursuant to Section 14.01(a)(ii)(A), the New Indenture Trustee shall
give the Notice of Optional Redemption upon receipt of notice from the Guarantor
that an Optional Redemption is to be effected pursuant to the foregoing clause.
In the case of an Optional Redemption pursuant to Section 14.01(a)(ii)(B), the
New Indenture Trustee shall give the Notice of Optional Redemption upon receipt
of notice from the Indenture Trustee or the Limestone Trustee, as applicable,
that an Optional Redemption is to be effected pursuant to the foregoing clause.
Any Notice of Optional Redemption shall be given to each New Noteholder by first
class mail or airmail, postage prepaid, at their last addresses as they shall
appear upon the Note Register. Any notice which is mailed in the manner herein
provided shall be conclusively presumed to have been duly given, whether or not
the New Holder receives the notice. Once Notice of Optional Redemption is mailed
in accordance with this Section 14.02, New Limestone Notes called for redemption
become irrevocably due and payable on the Optional Redemption Date at the

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<PAGE>

Optional Redemption Price. A Notice of Optional Redemption may not be
conditional. Failure to give such notice by mail or any defect in the notice to
any New Noteholder shall not affect the validity of the proceedings for the
redemption with respect to the New Limestone Notes held by other New
Noteholders. Each Notice of Optional Redemption shall be given at least 30 days
but not more than 60 days before the applicable Optional Redemption Date and
shall specify (a) the Optional Redemption Date; (b) the formula by which the
Optional Redemption Price will be calculated on the Optional Redemption Date,
and the amount of accrued and unpaid interest, if any, to be due as of the
Optional Redemption Date as a part of the Optional Redemption Price; (c) that on
the Optional Redemption Date, the Optional Redemption Price will become due and
payable upon each such New Limestone Note to be redeemed and that interest shall
cease to accrue on such New Limestone Note on and after such date; (d) if any
New Limestone Note is being redeemed in part, the portion of the principal
amount of such New Limestone Note to be redeemed and that, after the Optional
Redemption Date, upon surrender of such New Limestone Note, a new New Limestone
Note or new New Limestone Notes in principal amount equal to the unredeemed
portion shall be issued upon cancellation of the original New Limestone Note;
(e) the name and address of the Paying Agent; (f) that New Limestone Notes
called for redemption must be surrendered to the Paying Agent to collect the
Optional Redemption Price; (g) the paragraph of the New Limestone Notes and/or
the Section of this New Indenture pursuant to which the New Limestone Notes
called for redemption are being redeemed; and (h) that no representation is made
as to the correctness or accuracy of the CUSIP or ISIN number, if any, listed in
such notice or printed on the New Limestone Notes.

                  SECTION 14.03. Selection of New Limestone Notes to be
Redeemed. If less than all of the New Limestone Notes are to be optionally
redeemed, the New Indenture Trustee shall select the New Limestone Notes to be
redeemed or purchased among the New Holders of the New Limestone Notes on a pro
rata basis; provided that no New Limestone Notes of $100,000 or less shall be
redeemed in part.

                  The New Indenture Trustee shall promptly notify the Issuers in
writing of the New Limestone Notes selected for redemption and, in the case of
any New Limestone Note selected for partial redemption, the principal amount
thereof to be redeemed. New Limestone Notes and portions of New Limestone Notes
selected shall be in amounts of $100,000 or whole multiples of $1,000 in excess
thereof; except that if all of the New Limestone Notes of a New Holder are to be
redeemed, the entire outstanding amount of New Limestone Notes held by such New
Holder, even if not such a multiple of $1,000, shall be redeemed. Except as
provided in the preceding sentence, provisions of this New Indenture that apply
to the New Limestone Notes called for redemption also apply to portions of New
Limestone Notes called for redemption.

                  SECTION 14.04. Deposit of Optional Redemption Price.

                   (a) On or prior to 3:00 p.m., New York City time, on any
Optional Redemption Date of the New Limestone Notes, the Issuers shall deposit
or cause to be deposited into the New Notes Account an amount equal to the
Optional Redemption Price, for each New Limestone Note (or portion thereof)
being redeemed, together with any other amount necessary to be deposited with
the New Indenture Trustee so that each New Holder of a New Limestone Note is
able to receive the applicable Optional Redemption Price in full.

                  (b) If the Issuers comply with the provisions of paragraph (a)
above, on and after the Optional Redemption Date, interest shall cease to accrue
on the New Limestone Notes or the portions of the New Limestone Notes called for
Optional Redemption. If a New Limestone Note is redeemed in whole or in part on
or after a Record Date but on or prior to the related Limestone Note Payment
Date, then any accrued and unpaid interest shall be paid to the Person in whose
name such New Limestone Note was registered at the close of business on such
Record Date. If any New Limestone Note called for Optional Redemption shall not
be so paid upon surrender for redemption because of the failure of the Issuers
to comply with the provisions of (a) above, interest shall be paid on the unpaid
principal, from the

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<PAGE>

Optional Redemption Date until such principal is paid, and to the extent lawful
on any interest not paid on such unpaid principal, in each case at the Limestone
Note Rate.

                  SECTION 14.05. Payment of New Limestone Notes Called for
Optional Redemption. If a Notice of Optional Redemption has been given with
respect to the New Limestone Notes as provided in Section 14.02, such New
Limestone Notes (or portions thereof) to be redeemed shall become due and
payable on the date and at the place stated in such Notice of Optional
Redemption at the Optional Redemption Price payable pursuant to Section 14.01(e)
and on and after said date (unless the Issuers shall default in the payment of
the Optional Redemption Price) interest on such New Limestone Notes (or portions
thereof) to be redeemed shall cease to accrue and such New Limestone Notes shall
cease from and after the Optional Redemption Date to be entitled to any benefit
or other support under this New Indenture, and the New Noteholders shall have no
right in respect of such New Limestone Notes (or portion thereof) to be redeemed
except the right to receive the Optional Redemption Price with respect to each
such New Limestone Note. The New Limestone Notes (or portions thereof) to be
redeemed shall be paid and redeemed by the New Indenture Trustee in accordance
with Section 5.04(d) at the applicable Optional Redemption Price; provided that
any payment of interest becoming due on the Optional Redemption Date shall be
payable to the registered holders of such New Limestone Notes subject to the
applicable terms and provisions of Section 2.05.

                  SECTION 14.06. New Notes Redeemed in Part. Upon surrender of a
New Limestone Note that is redeemed in part, the Issuers shall issue and
execute, the Guarantor shall endorse and, upon the Issuers' written request, the
New Indenture Trustee shall authenticate for the New Holder, at the expense of
the Issuers, a new New Limestone Note equal in principal amount to the
unredeemed portion of the New Limestone Note surrendered.

                                   ARTICLE XV

                   MANDATORY REDEMPTION AND SPECIAL REDEMPTION

                  SECTION 15.01. Mandatory Redemption.

                  (a) [Reserved].

                  (b) [Reserved].

                  (c) Following the acceleration of the New Limestone Notes as a
result of an Event of Default but prior to the expiration of the 120-day
standstill referred to in Section 2.05(f)(ii), the New Limestone Notes shall be
redeemed if any of the following events (each, a "Take-Out Deposit") occurs:

                        (i)the Guarantor causes funds to be irrevocably
         deposited with the New Indenture Trustee, pursuant to Section 3.09, to
         be used to cause a Mandatory Redemption, or

                        (ii) the Indenture Trustee or Limestone, as the case may
         be, distributes funds to be irrevocably deposited with the New
         Indenture Trustee to be used to cause a Mandatory Redemption.

                  (d) When the New Limestone Notes have become subject to a
redemption pursuant to clause (c) above, the New Limestone Notes Outstanding
shall be redeemed (a "Mandatory Redemption") at the Mandatory Redemption Price
on the date or dates established by the New Indenture Trustee following the date
of the Take-Out Deposit (which date or dates shall be agreed upon by the New
Indenture Trustee and the Person(s) making such Take-Out Deposit and shall occur
as promptly as practicable following such Take-Out Deposit); provided that, in
the case of a Mandatory Redemption pursuant to Section 15.01(c)(ii) arising from
the Primary Class B Member electing to exercise the

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<PAGE>

Purchase Option or Retirement Option, such date shall be the Retirement Date or
Purchase Date, as applicable, set forth in the Retirement Notice or Purchase
Option Notice, as applicable, delivered to the Indenture Trustee and/or
Limestone pursuant to the Chaparral LLC Agreement (any such date, the "Mandatory
Redemption Date").

                   The "Mandatory Redemption Price" for each New Limestone Note
in any Mandatory Redemption will be equal to the accrued and unpaid interest
(including Default Interest, if any) to the Mandatory Redemption Date plus 100%
of the outstanding principal amount of such New Limestone Note, plus all other
amounts due and owing to such New Noteholder under this New Indenture; provided,
however, that if the New Limestone Notes have been accelerated as a result of an
Event of Default described in Section 9.01(a), the Mandatory Redemption Price
shall be equal to the Optional Redemption Price.

                  SECTION 15.02. Notice of Mandatory Redemption. Notice of a
Mandatory Redemption ("Notice of Mandatory Redemption") of the New Limestone
Notes pursuant to Section 15.01 shall be given by the New Indenture Trustee at
such time or times when the New Indenture Trustee has any Amount Available in
the New Notes Account (including amounts received as a result of a Take-Out
Deposit) to apply to the payment of the New Limestone Notes in accordance with
Section 5.04(c). Any Notice of Mandatory Redemption shall be given to each New
Noteholder by first class mail or airmail, postage prepaid, at their last
addresses as they shall appear upon the Note Register. Any such Notice which is
mailed in the manner herein provided shall be conclusively presumed to have been
duly given, whether or not the New Holder receives the notice. Each Notice of
Mandatory Redemption shall be given the number of days prior to each Mandatory
Redemption Date as the New Indenture Trustee may fix and shall specify, among
other things, (a) the Mandatory Redemption Date; (b) the Mandatory Redemption
Price, specifying the Limestone Interest Amount and any Default Interest; (c)
that on the Mandatory Redemption Date, the Mandatory Redemption Price will
become due and payable upon each such New Limestone Note to be redeemed and that
interest shall cease to accrue on such New Limestone Note on and after such
date; (d) the name and address of the Paying Agent; (e) that New Limestone Notes
must be surrendered to the Paying Agents to collect the Mandatory Redemption
Price; (f) the paragraph of the New Limestone Notes and/or the Section of this
New Indenture pursuant to which the New Limestone Notes are being redeemed; and
(g) that no representation is made as to the correctness or accuracy of the
CUSIP or ISIN number, if any, listed in such notice or printed on the New
Limestone Notes.

                  SECTION 15.03. Selection of New Limestone Notes to be
Redeemed. If less than all of the New Limestone Notes are to be redeemed on any
particular Mandatory Redemption Date, the New Limestone Notes shall be redeemed
on a pro rata basis.

                  The New Indenture Trustee shall promptly notify the Issuers in
writing of the amount of New Limestone Notes to be redeemed on any particular
Mandatory Redemption Date. Provisions of this New Indenture that apply to the
New Limestone Notes called for redemption also apply to portions of New
Limestone Notes called for redemption.

                  SECTION 15.04 Special Redemption.

                  (a) Following (i) the exercise of an Asset Remedy at the
direction of the Noteholders or the requisite Certificateholders in accordance
with the Indenture, or, after the Outstanding Limestone Notes have been repaid
in full, the requisite Certificateholders in accordance with the Limestone Trust
Agreement, or (ii) the occurrence of an Asset Disposition in accordance with the
Chaparral LLC Agreement in connection with the occurrence of a Specified Equity
Event, all or a portion of the New Limestone Notes shall be redeemed (without
limiting the mandatory redemption provisions in Sections 15.01, 15.02 and 15.03)
upon the distribution to the New Indenture Trustee of proceeds from the exercise
of such Asset Remedy or such Asset Disposition pursuant to Section 5.04(c) of
the Indenture or Section

                                       59
<PAGE>

6.04(b) of the Limestone Trust Agreement; provided that the aggregate amount to
be applied to such Special Redemption shall be no greater than the amount of
such proceeds.

                  (b) When the New Limestone Notes have become subject to a
redemption pursuant to clause (a) above, all or a portion of the New Limestone
Notes Outstanding shall be redeemed (a "Special Redemption") on a pro rata basis
at the Mandatory Redemption Price on the date or dates established by the New
Indenture Trustee following the date of receipt by the New Indenture Trustee of
any proceeds pursuant to Section 5.04(c) of the Indenture or Section 6.04(b) of
the Limestone Trust Agreement (the "Special Redemption Date").

                  SECTION 15.05. Notice of Special Redemption. Notice of a
Special Redemption ("Notice of Special Redemption") of the New Limestone Notes
pursuant to Section 15.04 shall be given by the New Indenture Trustee promptly
at such time or times when the New Indenture Trustee has received any proceeds
pursuant to Section 5.04(c) of the Indenture or Section 6.04(b) of the Limestone
Trust Agreement to apply to the payment of the New Limestone Notes in accordance
with Section 5.04(c). Any Notice of Special Redemption shall be given to each
New Noteholder by first class mail or airmail, postage prepaid, at its last
address as it shall appear upon the Note Register. Any such Notice which is
mailed in the manner herein provided shall be conclusively presumed to have been
duly given, whether or not the New Holder receives the notice. Each Notice of
Special Redemption shall be given the number of days prior to each Special
Redemption Date as the New Indenture Trustee may fix and shall specify, among
other things, (a) the Special Redemption Date; (b) the Mandatory Redemption
Price, specifying the Limestone Interest Amount and any Default Interest; (c)
that on the Special Redemption Date, the Mandatory Redemption Price will become
due and payable upon each such New Limestone Note to be redeemed and that
interest shall cease to accrue on such New Limestone Note on and after such
date; (d) if any New Limestone Note is being redeemed in part, the portion of
the principal amount of such New Limestone Note to be redeemed and that, after
the Special Redemption Date, upon surrender of such New Limestone Note, a new
New Limestone Note or new New Limestone Notes in principal amount equal to the
unredeemed portion shall be issued upon cancellation of the original New
Limestone Note; (e) the name and address of the Paying Agent; (f) that New
Limestone Notes must be surrendered to the Paying Agent to collect the Special
Redemption Price; (g) that such New Limestone Notes are being redeemed pursuant
to Section 15.04 of this New Indenture; and (h) that no representation is made
as to the correctness or accuracy of the CUSIP or ISIN number, if any, listed in
such notice or printed on the New Limestone Notes.

                  SECTION 15.06. Selection of New Limestone Notes to be
Redeemed. If less than all of the New Limestone Notes are to be redeemed on any
particular Special Redemption Date, the New Indenture Trustee shall select the
New Limestone Notes to be redeemed among the holders of the New Limestone Notes
on a pro rata basis; provided that no New Limestone Notes of $100,000 or less
shall be redeemed in part.

                  The New Indenture Trustee shall promptly notify the Issuers in
writing of the New Limestone Notes selected for redemption and, in the case of
any New Limestone Note selected for partial redemption, the principal amount
thereof to be redeemed. New Limestone Notes and portions of New Limestone Notes
selected shall be in amounts of $100,000 or whole multiples of $1,000 in excess
thereof; except that, if all of the New Limestone Notes of a New Noteholder are
to be redeemed, the entire Outstanding amount of New Limestone Notes held by
such New Noteholder, even if not such a multiple of $1,000, shall be redeemed.
Except as provided in the preceding two sentences, provisions of this New
Indenture that apply to the New Limestone Notes called for redemption also apply
to portions of New Limestone Notes called for redemption.

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                                   ARTICLE XVI

                                  MISCELLANEOUS

                  SECTION 16.01. Survival. All agreements, representations,
warranties and indemnities contained in this New Indenture and in any agreement,
document or certificate delivered pursuant hereto, or in connection herewith,
shall survive and continue in effect following the execution and delivery of
this New Indenture and the Effective Date. Upon the repayment in full of the New
Limestone Notes, this New Indenture shall terminate.

                  SECTION 16.02. Notices. Except as otherwise expressly provided
herein in any particular case, all notices, approvals, consents, requests and
other communications hereunder shall be in writing and shall, if addressed as
provided in the following sentence, be deemed to have been given, (i) when
delivered by hand, (ii) one Business Day after being sent by a private
nationally or internationally recognized overnight courier service, (iii) five
days after being sent by first class mail or airmail, postage prepaid or (iv)
when sent by telecopy, if immediately after transmission the sender's facsimile
machine records in writing the correct answer back. Actual receipt at the
address of an addressee, regardless of whether in compliance with the foregoing,
is effective notice hereunder. Until otherwise so notified by the respective
parties, all notices, approvals, consents, requests and other communications
shall be addressed to the following addressees:

         If to Limestone or the Co-Issuer:

         Limestone Electron Trust
         c/o Wilmington Trust Company
         Rodney Square North
         1100 North Market Street
         Wilmington, Delaware  19890-0001
         Attention:  Corporate Trust Administration
         Telecopier No.:  302-651-8882
         Telephone No.:  302-651-8681

         If to the New Indenture Trustee:

         The Bank of New York
         5 Penn Plaza
         New York, NY  10001
         Attention:  Louis P. Young
         Telecopier No.:  212-896-7299
         Telephone No.:  212-896-7249
         with a copy to:

         Seward & Kissel
         One Battery Park Plaza
         New York, New York  10004
         Attention:  Kalyan Das
         Telecopier No.:  212-480-8421
         Telephone No.:  212-574-1391

                                       61
<PAGE>

         If to El Paso:

         El Paso Corporation
         1001 Louisiana Street
         P.O. Box 2511
         Houston, Texas  77002
         Attention:  Tom Kilgore
         Telecopier No.:  713-420-7249
         Telephone No.:  713-420-5574

         with a copy to:

         El Paso Corporation
         1001 Louisiana Street
         P.O. Box 2511
         Houston, Texas  77002
         Attention:  Kelly Jameson
         Telecopier No.:  713-420-2529
         Telephone No.:  713-420-2017

         If to the Rating Agencies:

         Moody's Investors Service, Inc.
         99 Church Street
         New York, New York  10007-2701
         Attention:  Mihoko Manabe
         Telecopier No.:  212-553-0519
         Telephone No.:  212-553-1942

         Standard & Poor's Ratings Services
         25 Broadway
         New York, New York  10004
         Attention:  John Whitlock
         Telecopier No.:  212-438-2154
         Telephone No.:  212-438-7678

                  A duplicate copy of each notice, approval, consent, request or
other communication given hereunder by each of the parties, to any one of the
others or to the Certificateholders shall also be given to all of the others.
However, failure to give notice to any party shall not affect the effectiveness
of notice to parties as to whom notice has been given in accordance with this
Section 16.02. Each of the parties may, by notice given hereunder, designate any
further or different addresses to which subsequent notices, approvals, consents,
requests or other communications shall be sent or persons to whose attention the
same shall be directed.

                  SECTION 16.03. Severability of Provisions. If any provision
hereof shall be held invalid or unenforceable by any court of competent
jurisdiction, such holding shall not invalidate or render unenforceable any
other provision hereof. To the extent permitted by Applicable Law, the Issuers,
the Guarantor and the New Indenture Trustee hereby agree that any provision
hereof that renders any other term or provision hereof invalid or unenforceable
in any respect shall be modified, but only to the extent necessary to avoid
rendering such other term or provision invalid or unenforceable, and such
modification shall be accomplished in the manner that most nearly preserves the
benefit of the Issuers', the Guarantor's and the New Indenture Trustee's bargain
hereunder.

                                       62
<PAGE>

                  SECTION 16.04 Effect of Headings. The Table of Contents and
the headings of the Articles, Sections, subsections, clauses and paragraphs
hereof, and of Exhibits hereto, are for convenience of reference only, and shall
not affect the construction or interpretation of this New Indenture.

                  SECTION 16.05. Counterparts. This New Indenture may be
executed in any number of counterparts, each of which shall be an original; but
all such counterparts shall together constitute but one and the same instrument.

                  SECTION 16.06. Further Assurance. The Issuers and, solely with
respect to its obligations hereunder, the Guarantor shall, from time to time on
being required to do so by the New Indenture Trustee, now or at any time in the
future, do or procure the doing of all such acts and/or execute or procure the
execution of all such documents in a form reasonably satisfactory to the New
Indenture Trustee as the New Indenture Trustee may reasonably consider necessary
for giving full effect to this New Indenture and securing to the New Indenture
Trustee the full benefit of the rights, powers and remedies conferred upon the
New Indenture Trustee in this New Indenture.

                  SECTION 16.07 Governing Law; Waiver of Jury Trial.

                  (a) THE RIGHTS AND OBLIGATIONS OF EACH OF THE PARTIES UNDER
THIS NEW INDENTURE SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE
LAWS OF THE STATE OF NEW YORK.

                  (b) EACH OF THE PARTIES HEREBY IRREVOCABLY WAIVES TO THE
FULLEST EXTENT PERMITTED BY LAW ALL RIGHT TO TRIAL BY JURY IN ANY PROCEEDING
ARISING OUT OF OR RELATING DIRECTLY OR INDIRECTLY TO ANY OF THIS NEW INDENTURE
OR ANY OTHER TRANSACTION DOCUMENT (OTHER THAN THE NOTE PURCHASE AGREEMENT AND
THE DEALER MANAGER AGREEMENT) OR THE TRANSACTIONS CONTEMPLATED HEREBY OR THEREBY
(WHETHER BASED ON CONTRACT, TORT OR ANY OTHER THEORY). EACH PARTY (A) CERTIFIES
THAT NO REPRESENTATIVE, AGENT OR ATTORNEY OF ANY OTHER PARTY HAS REPRESENTED
EXPRESSLY OR OTHERWISE, THAT SUCH PARTY WOULD NOT, IN THE EVENT OF LITIGATION,
SEEK TO ENFORCE THE FOREGOING WAIVER AND (B) ACKNOWLEDGES THAT IT AND THE OTHER
PARTIES HAVE BEEN INDUCED TO ENTER INTO THIS NEW INDENTURE BY, AMONG OTHER
THINGS, THE MUTUAL WAIVERS AND CERTIFICATIONS IN THIS PARAGRAPH.

                  (c) ANY PROCEEDING WITH RESPECT TO THIS NEW INDENTURE OR ANY
OTHER TRANSACTION DOCUMENT (OTHER THAN THE NOTE PURCHASE AGREEMENT AND THE
DEALER MANAGER AGREEMENT) MAY BE BROUGHT IN THE COURTS OF THE STATE OF NEW YORK
IN THE COUNTY OF NEW YORK IN THE COMMERCIAL DIVISION OF THE SUPREME COURT, CIVIL
BRANCH OR OF THE UNITED STATES FOR THE SOUTHERN DISTRICT OF NEW YORK OR THE
EASTERN DISTRICT OF NEW YORK AND, BY EXECUTION AND DELIVERY OF THIS NEW
INDENTURE, EACH OF THE PARTIES HEREBY IRREVOCABLY ACCEPTS FOR ITSELF AND IN
RESPECT OF ITS PROPERTY, GENERALLY AND UNCONDITIONALLY, THE NON-EXCLUSIVE
JURISDICTION OF THE AFORESAID COURTS IN RESPECT OF, BUT ONLY IN RESPECT OF,
PROCEEDINGS WITH RESPECT TO THIS NEW INDENTURE OR ANY OTHER TRANSACTION
DOCUMENT.

                  (d) EACH PARTY HEREBY IRREVOCABLY WAIVES, TO THE FULLEST
EXTENT PERMITTED BY APPLICABLE LAW, ANY OBJECTION WHICH IT MAY NOW OR HEREAFTER
HAVE TO THE LAYING OF VENUE OF ANY OF THE AFORESAID PROCEEDINGS ARISING OUT OF
OR IN CONNECTION WITH THIS NEW INDENTURE OR ANY OTHER TRANSACTION DOCUMENT
BROUGHT IN THE COURTS REFERRED TO IN SECTION 16.07(c)

                                       63
<PAGE>

AND HEREBY FURTHER IRREVOCABLY WAIVES, TO THE FULLEST EXTENT PERMITTED BY
APPLICABLE LAW, AND AGREES NOT TO PLEAD OR CLAIM IN ANY SUCH COURT THAT ANY SUCH
PROCEEDING BROUGHT IN ANY SUCH COURT HAS BEEN BROUGHT IN AN INCONVENIENT FORUM.

                  (e) EACH OF LIMESTONE AND THE CO-ISSUER HEREBY IRREVOCABLY
DESIGNATES, APPOINTS AND EMPOWERS AND HEREBY CONFERS AN IRREVOCABLE SPECIAL
POWER, AMPLE AND SUFFICIENT, TO CT CORPORATION SYSTEM, WITH OFFICES ON THE DATE
HEREOF AT 111 EIGHT AVENUE, NEW YORK, NY 10011 AS ITS DESIGNEE, APPOINTEE AND
AGENT WITH RESPECT TO ANY SUCH PROCEEDING IN NEW YORK TO RECEIVE, ACCEPT AND
ACKNOWLEDGE FOR AND ON ITS BEHALF, AND IN RESPECT OF ITS PROPERTY, SERVICE OF
ANY AND ALL LEGAL PROCESS, SUMMONS, NOTICES AND DOCUMENTS WHICH MAY BE SERVED IN
ANY SUCH PROCEEDING AND AGREES THAT THE FAILURE OF SUCH AGENT TO GIVE ANY ADVICE
OF ANY SUCH SERVICE OF PROCESS TO LIMESTONE AND THE CO-ISSUER AS THE CASE MAY
BE, SHALL NOT IMPAIR OR AFFECT THE VALIDITY OF SUCH SERVICE OR OF ANY CLAIM
BASED THEREON. IF FOR ANY REASON SUCH DESIGNEE, APPOINTEE AND AGENT SHALL CEASE
TO BE AVAILABLE TO ACT AS SUCH, EACH OF LIMESTONE AND THE CO-ISSUER AGREES TO
DESIGNATE A NEW DESIGNEE, APPOINTEE AND AGENT IN NEW YORK CITY REASONABLY
SATISFACTORY TO THE NEW INDENTURE TRUSTEE ON THE TERMS AND FOR THE PURPOSES OF
THIS PROVISION. TO THE EXTENT PERMITTED BY APPLICABLE LAW, EACH OF LIMESTONE AND
THE CO-ISSUER HEREBY IRREVOCABLY CONSENTS TO THE SERVICE OF PROCESS WITH RESPECT
TO ANY PROCEEDING (WHETHER OR NOT IN NEW YORK), BY THE MAILING OF COPIES THEREOF
BY REGISTERED OR CERTIFIED MAIL, POSTAGE PREPAID, TO SUCH PERSON, AT ITS
RESPECTIVE ADDRESS SET FORTH IN SECTION 16.02, SUCH SERVICE TO BECOME EFFECTIVE
30 DAYS AFTER SUCH MAILING.

                  SECTION 16.08. Entire Agreement. This New Indenture
(including, without limitation, the exhibits hereto) and the New Limestone Notes
supersede all prior agreements, written or oral, between or among any of
Limestone, the Co-Issuer, the Guarantor and the New Indenture Trustee relating
to the transactions contemplated hereby and thereby, and each of the Issuers,
the Guarantor and the New Indenture Trustee represents and warrants to the
others that this New Indenture, the New Limestone Notes and the other
Transaction Documents constitute the entire agreement among the Issuers, the
Guarantor and the New Indenture Trustee relating to the transactions
contemplated hereby and thereby.

                  SECTION 16.09. Benefit of Agreement. All agreements,
representations, warranties and indemnities in this New Indenture and in any
agreement, document or certificate delivered pursuant hereto shall be binding
upon the Person making the same and its successors and assigns and shall inure
to the benefit of and be enforceable by the Person for whom made and its
successors and assigns. None of Limestone, the Co-Issuer or the Guarantor may
assign or transfer any of its rights or obligations hereunder without the prior
written consent of each other and the Majority New Noteholders, provided that no
such consent shall be required in connection with an assignment or transfer of
rights and obligations in connection with any merger, consolidation or other
transaction not in violation of Section 7.01(p) or Section 7.01(dd). The New
Indenture Trustee may transfer, assign or grant its rights and obligations
hereunder in connection with an assignment or transfer of all or any part of its
interest in accordance with the provisions of Sections 11.02, 11.03, 11.05 and
11.13, provided that any such assignee has agreed to be bound by the terms of
this New Indenture and the other Transaction Documents (other than the Note
Purchase Agreement and the Dealer Manager Agreement). This New Indenture is for
the sole benefit of the Limestone, the Co-Issuer, the Guarantor, the New
Indenture Trustee and the New Noteholders and their respective successors and
assigns, and is not for the benefit of any other Person; provided that the
Certificateholders shall be express third party beneficiaries for the purposes
of Sections 2.05(f)(v) and 3.01 of this New Indenture.

                                       64
<PAGE>

                  SECTION 16.10. Limitation on Rights of New Noteholders. No New
Noteholder shall have any right to vote (except as provided in this New
Indenture) or in any manner otherwise control the operation and management of
the Recourse for the Notes (except as provided in this New Indenture) or the
obligations of the parties hereto (except as provided in this New Indenture),
nor shall anything herein set forth or contained in the terms of the New
Limestone Notes be construed so as to constitute the New Noteholders from time
to time as partners or members of an association; nor shall any New Noteholder
be under any liability to any third party by reason of any action taken by the
parties to this New Indenture pursuant to any provision hereof, except as
expressly provided for herein.

                  No New Noteholder shall have any right by virtue or by
availing itself of any provisions of this New Indenture to institute any suit,
action or proceeding in equity or at law upon or under or with respect to this
New Indenture, unless such New Holder previously shall have given to the New
Indenture Trustee a written notice of an Event of Default and of the continuance
thereof, as hereinbefore provided, and unless the Majority New Noteholders shall
also have made written request upon the New Indenture Trustee to institute such
action, suit or proceeding in its own name as New Indenture Trustee hereunder
and shall have offered to the New Indenture Trustee such reasonable security or
indemnity (including reasonable advances) as it may require against the costs,
expenses, and liabilities to be incurred therein or thereby, and the New
Indenture Trustee, for 10 Business Days after its receipt of such notice,
request and offer of security or indemnity, shall have neglected or refused to
institute any such action, suit or proceeding; it being understood and intended,
and being expressly covenanted by each New Noteholder with the other New
Noteholders and the New Indenture Trustee, that no one or more New Holders of
New Limestone Notes shall have any right in any manner whatever by virtue or by
availing itself or themselves of any provisions of this New Indenture to affect,
disturb or prejudice the rights of the New Holders of any other of the New
Limestone Notes, or to obtain or seek to obtain priority over or preference to
any other such New Holder or to enforce any right under this New Indenture,
except in the manner herein provided and for the common benefit of all New
Noteholders. For the protection and enforcement of the provisions of this
Section 16.10, each and every New Noteholder and the New Indenture Trustee shall
be entitled to such relief as can be given either at law or in equity.

                  SECTION 16.11. [Reserved].

                  SECTION 16.12. Limitation of Liability of Wilmington Trust
Company. It is expressly understood and agreed by the parties hereto that (a)
this New Indenture is executed and delivered by Wilmington Trust Company, not
individually or personally, but solely as Limestone Trustee, in the exercise of
the powers and authority conferred and vested in it and (b) each of the
representations, undertakings and agreements herein made on the part of
Limestone and the Limestone Trustee is made and intended not as personal
representations, undertakings and agreements by Wilmington Trust Company but is
made and intended for the purpose of binding only Limestone and the Limestone
Trustee, as the case may be.

                  SECTION 16.13. New Limestone Notes Non-Assessable and Fully
Paid. It is the intention of the Issuers that the New Noteholders shall not be
personally liable for obligations of the Issuers and that the New Limestone
Notes, upon due authentication thereof by the New Indenture Trustee pursuant to
this New Indenture, are and shall be deemed fully paid.

                            [signature pages follow]

                                       65
<PAGE>

                  IN WITNESS WHEREOF, the undersigned have caused this New
Indenture to be duly executed as a deed as of this 26th day of April, 2002 by
their respective representatives hereunto duly authorized.

                                LIMESTONE ELECTRON TRUST, as Issuer

                                By:  Wilmington Trust Company,
                                     not in its individual capacity,
                                     but solely as Limestone Trustee

                                By:       /s/ James A. Hanley
                                     ------------------------------------
                                    Name:  James A. Hanley
                                    Title: Financial Services Officer

                                  New Indenture

<PAGE>
                               LIMESTONE ELECTRON, INC., as Co-Issuer

                               By:         /s/ Cecilia T. Heilmann
                                     ------------------------------------------
                                   Name:  Cecilia T. Heilmann
                                   Title: Vice President, Managing Director
                                          and Controller

                                  New Indenture

<PAGE>

                                  EL PASO CORPORATION, as Guarantor

                                  By:        /s/ David Siddall
                                        ------------------------------------
                                      Name:  David Siddall
                                      Title: Vice President

                                  New Indenture

<PAGE>
                           THE BANK OF NEW YORK, as New Indenture Trustee

                           By:        /s/ Louis P. Young
                                 ------------------------------------
                               Name:   Louis P. Young
                               Title:  Authorized Signatory

                           THE BANK OF NEW YORK, as Paying Agent for purposes
                           of Section 2.04(c) only

                           By:        /s/ Louis P. Young
                                 ------------------------------------
                               Name:   Louis P. Young
                               Title:  Authorized Signatory

                                  New Indenture

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