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                                                                    EXHIBIT 10.6

                  FRACTIONATION, STORAGE AND LOADING AGREEMENT
                                    (Siloam)

     This Fractionation, Storage and Loading Agreement ("Agreement") is made and
entered into this 24th day of May, 2002, by and between MARKWEST ENERGY
APPALACHIA, L.L.C., a Delaware limited partnership ("MEA"), and MARKWEST
HYDROCARBON, INC., a Delaware corporation ("MarkWest"). MEA and MarkWest may be
referred to individually as "Party", or collectively as "Parties".

     Section 1.    SCOPE OF AGREEMENT AND GENERAL TERMS AND CONDITIONS. MarkWest
agrees to deliver, or cause to be delivered, Raw Make, as defined below, to MEA,
and MEA agrees to receive and fractionate that Raw Make into Plant Products, as
defined below, and to store, load and deliver Plant Products to MarkWest, all in
accordance with this Agreement. This Agreement incorporates and is subject to
all of the General Terms and Conditions attached hereto, together with any other
Exhibits attached hereto.

     Section 2.    EFFECTIVE DATE. The date on which the obligations and duties
of the Parties shall commence, being the "Effective Date", shall be May 24th,
2002.

     Section 3.    TERM. This Agreement shall remain in full force and effect
from the Effective Date for a period of 10 years (the "Primary Term"), and shall
continue thereafter on a year-to-year basis until terminated by either Party by
providing at least 60 days written notice to the other Party in advance of the
termination of the Primary Term or of any one-year extension thereof.

     Section 4.    FEES AND CONSIDERATION.

     A. As full consideration for the services provided by MEA, MarkWest shall
     pay the following fees and MEA shall make the following deliveries:

             i.    For the fractionation of Raw Make into Plant Products, by
             MEA, at Siloam, MarkWest shall pay MEA a Fractionation Fee equal to
             the gallons of Raw Make fractionated multiplied by $*. The
             Fractionation Fee covers, and is inclusive of the MEA's costs for
             fractionating Raw Make, loading Plant Products and above ground
             storage of Plant Products.

             ii.   For the exclusive use of the Cavern, MarkWest shall pay MEA
             an Annual Storage Fee equal to $* for MEA storing MarkWest's Plant
             Products in the Cavern.

             iii.  Should MarkWest deliver any Raw Make to Siloam by railcar,
             MEA shall unload the Raw Make for fractionation and MarkWest shall
             pay MEA an Unloading Fee of $* per gallon of Raw Make unloaded from
             railcars.

             iv.   A portion of each of the Fractionation Fee, Annual Storage
             Fee and Unloading Fee (collectively, the "Fees") shall be subject
             to annual adjustments. *% of each of the Fees, shall be adjusted on
             an annual basis in proportion to the percentage change, from the
             preceding year, in the Producer Price Index for oil and gas field
             services (SIC 138) as published by the Department of Labor

                   * Denotes Confidential Portion Omitted and
                      Filed Separately with the Commission

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             ("PPI"). The adjustment of the Fees shall be made effective January
             1 of each year, and shall reflect the percentage change in the PPI
             as it existed for the immediately preceding January from the PPI
             for the second immediately preceding January.

             v.    MEA shall deliver and load the Plant Products fractionated
             from MarkWest's Raw Make to the Product Delivery Points in
             accordance with the terms of this Agreement.

     Section 5.    NOTICES. All notices, statements, invoices or other
communications required or permitted between the Parties shall be in writing and
shall be considered as having been given if delivered by mail, courier, hand
delivery, or facsimile to the other Party at the designated address or facsimile
numbers. Normal operating instructions can be delivered by telephone or other
agreed means. Notice of events of Force Majeure may be made by telephone and
confirmed in writing within a reasonable time after the telephonic notice.
Monthly statements, invoices, payments and other communications shall be deemed
delivered when actually received. Either Party may change its address or
facsimile and telephone numbers upon written notice to the other Party:

     MarkWest:

             Address:    155 Inverness Drive West, Suite 200
                         Englewood, Colorado 80112
                         Attn: Contract Administration
                         Fax: (303) 290-8769

     MEA:

             Address:    155 Inverness Drive West, Suite 200
                         Englewood, Colorado 80112
                         Attn: Contract Administration
                         Fax: (303) 290-8769

     Section 6.    EXECUTION. This Agreement may be executed in any number of
counterparts, each of which shall be considered and original, and all of which
shall be considered one instrument.

IN WITNESS WHEREOF, the Parties have executed this Agreement on the date first
set forth above.

                                           MARKWEST HYDROCARBON, INC.


                                           By:  /S/ ARTHUR J. DENNEY
                                              -------------------------------
                                           Name:  Arthur J. Denney
                                           Title: Executive Vice President

                                           MARKWEST ENERGY APPALACHIA, L.L.C.

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                                           By:  /S/ GERALD A. TYWONIUK
                                              -------------------------------
                                           Name:  Gerald A. Tywoniuk
                                           Title: Senior Vice President and
                                                  Chief Financial Officer

3
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                          GENERAL TERMS AND CONDITIONS
                   ATTACHED TO AND MADE A PART OF THAT CERTAIN
                  FRACTIONATION, STORAGE AND LOADING AGREEMENT
                                     BETWEEN
                    MARKWEST HYDROCARBON, INC., AS "MARKWEST"
                                       AND
                  MARKWEST ENERGY APPALACHIA, L.L.C., AS "MEA"
                                     DATED:

ARTICLE 1:    DEFINITIONS

ACCOUNTING PERIOD. The period commencing at 10:00 a.m., Eastern Time, on the
first day of a calendar month and ending at 10:00 a.m., Eastern Time, on the
first day of the next succeeding month.

CAVERN. The two underground Plant Products storage cavern owned and operated by
MEA at Siloam with a capacity of approximately 11,000,000 gallons.

FORCE MAJEURE. Any cause or condition not within the reasonable control of the
Party claiming suspension and which by the exercise of reasonable diligence,
such Party is unable to prevent or overcome.

FRACTIONATION FUEL. All Gas, Plant Products, vapors or other forms of energy
utilized as fuel in Siloam.

GAS. All hydrocarbon and non-hydrocarbon substances in a gaseous state.

INCIDENTAL LOSSES OR GAINS. The incidental losses of Raw Make and/or Plant
Products incurred in MEA's facilities, or the losses or gains of Raw Make and/or
Plant Products incurred due to variations in measurement equipment.

INDEMNIFYING PARTY and INDEMNIFIED PARTY. As defined in Article 8, below.

LOSSES. Any actual loss, cost, expense, liability, damage, demand, suit,
sanction, claim, judgment, lien, fine or penalty which are incurred by the
applicable Indemnified Party on account of injuries (including death) to any
person or damage to or destruction of any property, sustained or alleged to have
been sustained in connection with or arising out of the matters for which the
Indemnifying Party has indemnified the applicable Indemnified Party.

MEA PLANTS. Gas processing and extraction plants, owned and/or operated by MEA.

PLANT PRODUCTS. The finished liquid products fractionated from the Raw Make
delivered hereunder, including propane (including incidental ethane), isobutane,
normal butane and natural gasoline.

PLANT PRODUCTS DELIVERY POINT. The point at which the Plant Products are
delivered to, or for the account of, MarkWest into transportation facilities
furnished by MarkWest.

RAW MAKE. A combined stream of propane and heavier liquefied hydrocarbons,
including incidental ethane.

RECEIPT POINT. For Raw Make, the inlet flange of the pipeline at the point at
which MarkWest delivers Raw Make into the pipeline, and for Raw Make delivered
by truck trailer or by tank car, the inlet flange of the Raw Make unloading
facilities of MEA at or near Siloam.

SILOAM. MEA's Siloam fractionation facility located near South Shore, Kentucky,
including any treating equipment, Plant Products separation and fractionation

1 of General Terms and Conditions
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vessels, all above ground Plant Products storage vessels and all below ground
Plant Products and Raw Make storage caverns and facilities, and associated
condensing, heating, pumping, conveying, and other equipment and
instrumentation; including all structures associated with those facilities; and,
all Plant Products loading facilities, including railcar loading, truck loading
and barge loading facilities and including all easements, rights-of-way, and
other property rights pertaining to the construction and operation of those
facilities; wherever those facilities, structures, easements, rights-of-way, and
other property rights are located.

ARTICLE 2:    MARKWEST COMMITMENTS

2.1.   MarkWest hereby commits and agrees to deliver at the Receipt Points all
of MarkWest's Raw Make acquired from the MEA Plants, or from other extraction
plants in the Appalachian region, unless there is not sufficient available
capacity at Siloam to fractionate any portion thereof, in which case MarkWest
shall not be obligated to deliver the portion for which there is no capacity.

ARTICLE 3:    OPERATION OF MEA'S FACILITIES

3.1.   Subject to the other provisions of this Agreement, MEA agrees to accept
all of MarkWest's Raw Make, up to the capacity of Siloam, fractionate the Raw
Make into Plant Products in accordance with this Agreement and to store and load
Plant Products for MarkWest as provided herein.

3.2    MEA agrees that it shall, at its sole cost, risk, and expense, furnish
all Fractionation Fuel for operating Siloam, and in no event shall any of
MarkWest's Raw Make delivered hereunder or Plant Products or any vapors
therefrom be consumed or utilized by MEA as Fractionation Fuel or in any other
manner prior to delivery of Plant Products to MarkWest as herein provided.

3.3    MEA agrees that it shall, at its sole cost, risk, and expense, operate,
maintain, and replace (if necessary) docks, loading racks, pipelines, and all
other facilities for loading each Product for shipment by highway, rail, and
marine transportation from the vicinity of Siloam. MEA agrees that all
facilities operated by MEA which are required in the performance of the services
herein agreed upon shall, at its sole cost, risk, and expense, be maintained and
operated at all times as a prudent operator would maintain and operate similar
facilities. MEA hereby grants MarkWest, at no additional consideration, the
trackage rights on MEA's Siloam railroad siding to move Product hereunder.

3.4.   MEA agrees that it shall, at its sole cost, risk, and expense, be
responsible for all loading of each Product for shipments in accordance with
reasonable authorizations and instructions given from time to time by MarkWest,
including, but not limited to, preparation and distribution of all shipping
papers pertaining to movement of Plant Products from Siloam, rail, truck and
barge bills of lading, loading tickets, and reports and odorization
certifications. MEA shall furnish all trained employees required to perform
these services and shall maintain complete records of all Product dispositions.

3.5.   MEA agrees that it shall, at its sole risk, be responsible for placing
Plant Products into storage in the Cavern and withdrawing Plant Products from
the Cavern in accordance with reasonable authorizations and instructions given
from time to time by MarkWest.

3.6    All Incidental Losses and Gains incurred at Siloam shall be allocated to
MarkWest and other parties for whom MEA is fractionating Raw Make at Siloam.

ARTICLE 4:    QUALITY

4.1.   RAW MAKE QUALITY.

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A.     The Raw Make fractionated under this Agreement is derived from MEA
Plants, and from other plants. As long as the Raw Make delivered hereunder for
fractionation is of a quality which, when fractionated, meets the applicable
specifications set forth on Exhibit A, attached hereto, then MEA agrees to
receive and fractionate that Raw Make into Plant Products meeting the
specifications set forth herein.

B.     Should any of the Raw Make fail to meet the above specifications, then:

       i.   MEA may take receipt of the non-conforming Raw Make, and that
       receipt shall not be construed as a waiver or change of standards for
       future Raw Make deliveries; or

       ii.  MEA may, at its sole discretion, cease receiving the non-conforming
       Raw Make, and shall notify MarkWest that it has, or will, cease receiving
       the non-conforming Raw Make.

4.2    PLANT PRODUCTS QUALITY. MEA shall fractionate all Raw Make meeting the
requirements under Section 4.1, to produce Plant Products meeting the
specifications set forth on Exhibit A, attached hereto.

4.3    MEA shall odorize Plant Products in accordance with the directions of
MarkWest.

ARTICLE 5:    MEASUREMENT EQUIPMENT AND PROCEDURES AND ANALYSES

5.1.   RAW MAKE. Raw Make shall be measured at the respective Receipt Point(s)
and shall conform to applicable API and GPA standards for pipeline, truck, and
rail car measurement as follows:

      (1) For Raw Make delivered by pipeline:

A. MEA shall measure the weight of the Raw Make delivered hereunder using either
turbine or coriolis mass flow meters installed, operated and maintained in
accordance with GPA Standard 8182-latest edition and/or API Manual of Petroleum
Measurement Standards Draft Standard, Measurement of Single-Phase, Intermediate
and Finished Hydrocarbon Fluids by Coriolis Meters-latest edition.

B. MEA shall measure the composition of the Raw Make delivered hereunder using a
chromatograph installed, operated and maintained in accordance with GPA Standard
2165-latest edition, GPA Standard 2145-latest edition, GPA Standard 2261-latest
edition, GPA Standard 2177-latest edition and the manufacturer's specifications
and standards. Factors for hexanes and heavier shall be in accordance with Table
IV of GPA Standard 2261-latest edition or determined by periodic samples taken
by the MEA. Samples shall be taken at intervals not to exceed 20 minutes. The
arithmetic average of the samples during a day shall be deemed to be the Raw
Make Composition for such day.

C. The weight of each Raw Make component shall be converted to gallons at
60DEG.F in accordance with GPA Standard 8173-latest edition and GPA Standard
2145-latest edition.

      (2) The trucks shall be weighed empty and full. GPA Standard 8186, as
revised, is the standard to be used on all truck deliveries.

      (3) Rail cars shall be measured using strapping tables and liquid spew
gauges. Vapor correction calculations will be made as required by applicable
industry standards.

5.2    PLANT PRODUCTS MEASUREMENT.

3 of General Terms and Conditions
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Measurement of all Plant Products and deliveries shall be converted to 60 DEG.F
and shall conform to applicable API and GPA standards for barge, truck, and rail
car measurement:

      (1) Barge loading will be by strapping tables. Vapor correction will be
included on delivery tickets on all Plant Products except gasoline.

      (2) The trucks shall be weighed empty and full. GPA Standard 8186, as
revised, is the standard to be used on all truck deliveries.

      (3) Rail cars shall be measured using strapping tables and liquid spew
gauges. Vapor correction calculations will be made as required by applicable
industry standards.

5.3    If any measuring equipment used herein is out of service or, upon test,
is found to be in error by an amount exceeding 1%, at a recording rate
corresponding to the average rate of flow for the period since the last
preceding test, then any preceding recordings of that equipment since the last
preceding test shall be corrected to zero error for any period which is known
definitely or agreed upon. If the period is not known definitely or agreed upon,
the correction shall be for a period extending back one-half of the time elapsed
since the last test. In the event a correction is required for previous
deliveries, the volumes delivered shall be calculated by the first of the
following methods which is feasible: (i) by using the registration of any check
meter or meters if installed and accurately registering; or (ii) by correcting
the error if the percentage of error is ascertainable by calibration, test, or
mathematical calculations; or (iii) by MarkWest estimating the quantity of
delivery by deliveries during periods of similar conditions when the meter was
registering accurately.

5.4    INVENTORY.

A.     MEA will maintain and provide MarkWest with daily reports setting forth
the volumes of MarkWest's Raw Make and Plant Products held in inventory at
Siloam.

B.     MEA shall measure the inventory of each above ground storage tank using
tank gauges and shall measure the inventory in the Cavern using inlet and outlet
meters and gauges. Such meters and gauges shall be installed, operated and
maintained in accordance with applicable industry standards.

C.     At MarkWest's request, MEA shall operate the Cavern(s) in either propane
or butane service; provided, that MarkWest pays MEA in advance for all
reasonable and necessary costs to convert from one service to the other.

5.5    ANALYSES.

A.     MEA shall, at its sole cost, risk, and expense, install, operate, and
maintain equipment to analyze the composition of the Raw Make and of the Plant
Products in accordance with applicable GPA standards.

B.     With respect to Raw Make delivered by tank and truck cars, and with
respect to Plant Products, samples shall be analyzed in accordance with
applicable GPA standards. The analysis shall also include the determination of
the molecular weight, density, and heating value of the hexane and heavier
fraction be extended analysis, quarterly in accordance with industry recognized
standards. MarkWest or MEA or their representatives may take samples for
verification of composition and may be present during any of the other party's
sampling operations.

ARTICLE 6:    PAYMENTS

6.1.   MEA shall provide MarkWest with a statement explaining fully how all

4 of General Terms and Conditions
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consideration due under the terms of this Agreement was determined not later
than the 20th day of the Accounting Period following the Accounting Period for
which the consideration is due.

6.2.   Any sums due MEA under this Agreement shall be paid no later than the
last day of the Accounting Period in which the statement provided under Section
6.1 was received.

6.3.   Either Party, on 10 days prior written notice, shall have the right at
its expense, at reasonable times during business hours, to audit the books and
records of the other Party to the extent necessary to verify the accuracy of any
statement, measurement, computation, charge, or payment made under or pursuant
to this Agreement. A Party electing to audit ("Auditing Party") shall complete
its audit within 3 months following the date on which the books and records of
the other Party ("Audited Party") are first made available for inspection
following the Auditing Party's notice of audit. Within that 3-month period, the
Auditing Party shall submit, in writing, all exceptions disclosed by the audit
to the Audited Party. The Audited Party shall have 30 days following receipt of
the exceptions in which to respond in writing to the exceptions. If the Audited
Party fails to respond within that 30-day period, the exceptions shall be deemed
accepted and appropriate adjustments and settlements shall be made and, as
applicable, paid. If the Parties are unable to reach agreement as to any
exceptions to which the Audited Party timely responded within 30 days of the
Audited Party's response, then either Party may submit the matter to arbitration
in accordance with the provisions in Article 9.

ARTICLE 7:    FORCE MAJEURE

7.1.   In the event a Party is rendered unable, wholly or in part, by Force
Majeure, to carry out its obligations under this Agreement, other than the
obligation to make any payments due hereunder, the obligations of that Party, so
far as they are affected by Force Majeure, shall be suspended from the inception
and during the continuance of the inability, and the cause of the Force Majeure,
as far as possible, shall be remedied with commercially reasonable diligence.
The Party affected by Force Majeure shall provide the other Party with written
notice of the Force Majeure event, with reasonably full detail of the Force
Majeure within a reasonable time after the affected Party learns of the
occurrence of the Force Majeure event. The settlement of strikes, lockouts, and
other labor difficulty shall be entirely within the discretion of the Party
having the difficulty and nothing herein shall require the settlement of
strikes, lockouts, or other labor difficulty.

ARTICLE 8:    LIABILITY AND INDEMNIFICATION

8.1.   As among the Parties hereto, MarkWest and any of its designees shall be
in custody, control and possession of the Raw Make hereunder, until the Raw Make
is delivered to MEA at the Receipt Point, and shall be in custody control and
possession of the Plant Products after the Plant Products are loaded by MEA into
transportation facilities provided by MarkWest.

8.2.   As among the Parties hereto, MEA and any of its designees shall be in
custody, control and possession of the Raw Make hereunder after Raw Make is
delivered at the Receipt Point and shall be in custody, control and possession
of the Plant Products until the Plant Products are loaded by MEA into
transportation facilities provided by MarkWest.

8.3.   Each Party ("Indemnifying Party") hereby covenants and agrees with the
other Party, and its affiliates (except for the Indemnifying Party itself), and
each of their directors, officers and employees ("Indemnified Parties"), that
except to the extent caused by the Indemnified Parties' gross negligence or
willful conduct, the Indemnifying Party shall protect, defend,

5 of General Terms and Conditions
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indemnify and hold harmless the Indemnified Parties from, against and in respect
of any and all Losses incurred by the Indemnified Parties to the extent those
Losses arise from or are related to: (a) the Indemnifying Party's facilities; or
(b) the Indemnifying Party's possession and control of the Raw Make or Plant
Products, as applicable.

ARTICLE 9:    MISCELLANEOUS

9.1.   The failure of any Party hereto to exercise any right granted hereunder
shall not impair nor be deemed a waiver of that Party's privilege of exercising
that right at any subsequent time or times.

9.2.   This Agreement shall be governed by, construed, and enforced in
accordance with the laws of the State of Colorado without regard to choice of
law principles.

9.3.   This Agreement shall extend to and inure to the benefit of and be binding
upon the Parties, and their respective successors and assigns, including any
assigns of MarkWest's Interests covered by this Agreement. No assignment of this
Agreement shall be binding on either of the Parties until the first day of the
Accounting Period following the date a certified copy of the instrument
evidencing that sale, transfer, assignment or conveyance has been delivered to
the other Party. Further, each assigning Party shall notify its assignee of the
existence of this Agreement and obtain a ratification of this Agreement prior to
such assignment. No assignment by either Party shall relieve that Party of its
continuing obligations and duties hereunder without the express consent of the
other Party.

9.4.   Any change, modification or alteration of this Agreement shall be in
writing, signed by the Parties; and, no course of dealing between the Parties
shall be construed to alter the terms of this Agreement.

9.5    This Agreement, including all exhibits and appendices, contains the
entire agreement between the Parties with respect to the subject matter hereof,
and there are no oral or other promises, agreements, warranties, obligations,
assurances, or conditions precedent, affecting it.

9.6    NO BREACH OF THIS AGREEMENT OR CLAIM FOR LOSSES UNDER ANY INDEMNITY
OBLIGATION CONTAINED IN THIS AGREEMENT SHALL CAUSE ANY PARTY TO BE LIABLE FOR,
NOR SHALL LOSSES INCLUDE, ANY DAMAGES OTHER THAN ACTUAL AND DIRECT DAMAGES, AND
EACH PARTY EXPRESSLY WAIVES ANY RIGHT TO CLAIM ANY OTHER DAMAGES, INCLUDING,
WITHOUT LIMITATION, CONSEQUENTIAL, SPECIAL, INDIRECT, PUNITIVE OR EXEMPLARY
DAMAGES.

9.7    DISPUTE RESOLUTION. Any dispute arising under this Agreement ("Arbitrable
Dispute") shall be referred to and resolved by binding arbitration in Denver,
Colorado, by three (3) arbitrators, in accordance with the rules and procedures
of the Judicial Arbiter Group ("JAG"); and, to the maximum extent applicable,
the Federal Arbitration Act (Title 9 of the United States Code). If there is any
inconsistency between this Section and any statute or rules, this Section shall
control. Arbitration shall be initiated within the applicable time limits set
forth in this Agreement and not thereafter or if no time limit is given, within
the time period allowed by the applicable statute of limitations, by one party
("Claimant") giving written notice to the other party ("Respondent") and to JAG,
that the Claimant elects to refer the Arbitrable Dispute to arbitration, and
that the Claimant has appointed an arbitrator, who shall be identified in such
notice. The Respondent shall notify the Claimant and JAG within thirty (30) Days
after receipt of Claimant's notice, identifying the arbitrator the Respondent
has appointed. The two (2) arbitrators so chosen shall select a third arbitrator
within thirty (30) Days after the

6 of General Terms and Conditions
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second arbitrator has been appointed (upon failure of a party to act within the
time specified for naming an arbitrator, such arbitrator shall be appointed by
the administrator's designee). MarkWest shall pay the compensation and expenses
of the arbitrator named by or for it, MEA shall pay the compensation and
expenses of the arbitrator named by or for it, and MarkWest and MEA shall each
pay one-half of the compensation and expenses of the third arbitrator. All
arbitrators must be neutral parties who have never been officers, directors,
employees, contractors or agents of the parties or any of their Affiliates, must
have not less than ten (10) years experience in the oil and gas industry, and
must have a formal financial/accounting, engineering or legal education. The
parties shall have all rights of discovery in accordance with the Federal Rules
of Civil Procedure. The hearing shall be commenced within thirty (30) Days after
the selection of the third arbitrator. The parties and the arbitrators shall
proceed diligently and in good faith in order that the arbitral award shall be
made as promptly as possible. The interpretation, construction and effect of
this Agreement shall be governed by the laws of Colorado, and to the maximum
extent allowed by law, in all arbitration proceedings the laws of Colorado shall
be applied, without regard to any conflicts of laws principles. All statutes of
limitation and of repose that would otherwise be applicable shall apply to any
arbitration proceeding. The tribunal shall not have the authority to grant or
award indirect or consequential damages, punitive damages or exemplary damages.

7 of General Terms and Conditions
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                                    EXHIBIT A

                         PRODUCTS QUALITY SPECIFICATIONS

PROPANE

<Table>
<Caption>
                                                                                TEST METHODS
      PRODUCT CHARACTERISTICS           MINIMUM            MAXIMUM            LATEST REVISION
      -----------------------           -------            -------            ---------------
<S>                                       <C>        <C>                        <C>
1.  COMPOSITION                                                                 ASTM E-260
PERCENT BY LIQUID VOLUME:

Ethane                                               As limited by other
                                                     components and vapor
                                                           pressure

HD-5 Propane                              90                  100

Propylene                                                      5

Butanes & Heavier                                             2.5               ASTM D-2163

2.  VAPOR PRESSURE (psig @ 100                                208               ASTM D-1267
degrees F.)

3.  CORROSION
Copper Strip @ 100 deg. F.                                    1-b               ASTM D-1838

4.  TOTAL SULFUR (PPM by weight                               123               ASTM D-2784
in liquid)

5.  NON-VOLATILE RESIDUE
       a) Milliliters @ 100 deg. F.                          0.05               ASTM D-2158
                       b) Oil Stain                          Pass
</Table>

8 of General Terms and Conditions
<Page>

NORMAL BUTANE

<Table>
<Caption>
                                                                                TEST METHODS
      PRODUCT CHARACTERISTICS           MINIMUM            MAXIMUM            LATEST REVISION
      -----------------------           -------            -------            ---------------
<S>                                       <C>              <C>                  <C>
1.  COMPOSITION                                                                  ASTM E-260
PERCENT BY LIQUID VOLUME:

Isobutane and Lighter                                         5                 ASTM D-2163

Butylene (Percent of N. Butane)                               1

Normal Butane & Butylene                  95                 100                  GPA 2165

Pentanes & Heavier                                            2

2.  VAPOR PRESSURE (psig @ 100                               50                 ASTM D-1267
degrees F.)

3.  CORROSION
Copper Strip @ 100 deg. F.                                   1-b                ASTM D-1838

4.  TOTAL SULFUR (PPM by weight                              140                ASTM D-3246
in liquid)

5.  VOLATILE RESIDUE
95% Evaporated-Temperature,                                plus 36              ASTM D-1837
degrees F.
</Table>

9 of General Terms and Conditions
<Page>

ISOBUTANE

<Table>
<Caption>
                                                                                TEST METHODS
      PRODUCT CHARACTERISTICS           MINIMUM            MAXIMUM            LATEST REVISION
      -----------------------           -------            -------            ---------------
<S>                                       <C>           <C>                     <C>
1.  COMPOSITION                                                                 ASTM E-260
PERCENT BY LIQUID VOLUME:

Propane, Propylene and Lighter                                3                 ASTM D-2163

Isobutane                                 96                 100

Butylene, Normal Butane & Heavier                             4


2.  VAPOR PRESSURE (psig @ 100                               62                 ASTM D-1267
degrees F.)

3.  CORROSION
Copper Strip @ 100 deg. F.                                   1-b                ASTM D-1838

4.  TOTAL SULFUR (PPM by weight                              140                ASTM D-3246
in liquid)

5.  VOLATILE RESIDUE
95% Evaporated-Temperature,                                plus 16              ASTM D-1837
degrees F.

6.  DRYNESS                                             No free water             Visual
</Table>

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<Page>

NATURAL GASOLINE

<Table>
<Caption>
                                                                               TEST METHODS
      PRODUCT CHARACTERISTICS           MINIMUM            MAXIMUM           LATEST REVISION
      -----------------------           -------            -------           ---------------
<S>                                     <C>             <C>                   <C>
1.  COMPOSITION                                                                 ASTM E-260
PERCENT BY LIQUID VOLUME:

Butanes and Lighter                                           3                  GPA 2165

Pentanes & Heavier                        97                 100

2.  VAPOR PRESSURE (psig @ 100                               14                ASTM D-323
degrees F.)

3.  CORROSION
Copper Strip @ 104 deg. F.                                   1-b                ASTM D-130

4.  DOCTOR TEST                                           Negative              GPA 1138

5.  DRYNESS                                             No free water             Visual

6.  COLOR                                                 No Color           Field White Cup
                                                                                 Method
            Saybolt No.                 plus 25                              Lab-ASTM D-156

7.  DISTILLATION
        End Point, deg. F.                                   375               ASTM D-216

</Table>

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