Exhibit 10.30  SPECIFIC TERMS IN THIS EXHIBIT HAVE BEEN REDACTED BECAUSE
CONFIDENTIAL TREATMENT FOR THOSE TERMS HAS BEEN REQUESTED. THE REDACTED
MATERIAL HAS BEEN SEPERATELY FILED WITH THE SECURITIES AND EXCHANGE COMMISSION,
AND THE TERMS HAVE BEEN MARKED AT THE APPROPRIATE PLACE WITH TWO ASTERISKS
(**).  AMENDMENT TO GAS PROCESSING AGREEMENT  This Amendment to Gas Processing
Agreement (Amendment) is made and entered
into this 11th day of December, 2007, by and between Markwest
Javelina Company (Processor) and
CITGO Refining and Chemicals Company, L.P. (Supplier).  RECITALS  A.            Processor and Supplier are parties to that certain Gas
Processing Agreement made and entered into effective November 1, 2007 (the
Gas Processing Agreement).  B.            Processor and Supplier desire to enter into this
Amendment to correct and clarify certain inadvertent mutual mistakes and
omissions as contained in the Gas Processing Agreement executed by the parties.  NOW, THEREFORE, in consideration
of the mutual covenants and agreements contained herein, the parties agree as
follows:  1.             Section 10.1 of the Gas Processing Agreement is
hereby amended to delete the date July 1, 2007 and replace it with the
date November 1, 2007.  2.             The Gas Processing Agreement is hereby amended by
deleting Exhibit B attached thereto and replacing it with the complete Exhibit B
attached to this Amendment.  3.             Except for the foregoing, all other terms and provisions
of the Gas Processing Agreement shall remain in full force and effect.  4.             This Amendment may be executed in counterparts, each of
which shall be deemed an original but which together shall constitute one and
the same instrument.  IN WITNESS WHEREOF, this
Amendment is executed effective by the parties as of the date hereof.  Supplier: CITGO
REFINING AND CHEMICALS COMPANY, L.P.  By:
  /s/
  DOYLE P. DOMMERTName:
  Doyle
  P. DommertTitle:
  GM,
  Petrochemicals


Processor: MARKWEST
JAVELINA COMPANY  By:
  /s/
  FRANK M. SEMPLEName:
  Frank
  M. SempleTitle:
  President
  and CEO


EXHIBIT B  Plant Allocation
Statement Statement 1 of Exhibit B  Statement 1  Javelina Plant Allocation Measurement and Analysis Data Month, Year  Molecular Analysis  Inlet
  
  
  
  
  
  InletMeter
  
  Residue
  
  Inlet Gas
  
  Meter
  
  Residue
  
  Inlet Gas#441-207
  
  Meter
  
  Gallons
  
  Pounds
  
  #441-200
  
  Meter
  
  Gallons
  
  PoundsPer Mcf
  
  
  
  
  
  Per McfHydrogen
  
  **
  
  0.00
  %
  
  
  
  
  **
  
  0.00
  %Nitrogen
  
  **
  
  0.00
  %
  
  
  
  
  **
  
  0.00
  %CO1
  
  **
  
  0.00
  %
  
  
  
  
  **
  
  0.00
  %CO2
  
  **
  
  0.00
  %
  
  
  
  
  **
  
  0.00
  %Methane
  
  **
  
  0.00
  %
  
  
  
  
  **
  
  0.00
  %Ethane
  
  **
  
  0.00
  %
  **
  
  **
  
  **
  
  0.00
  %
  **
  
  **Ethylene
  
  **
  
  0.00
  %
  **
  
  **
  
  **
  
  0.00
  %
  **
  
  **Propane
  
  **
  
  0.00
  %
  **
  
  **
  
  **
  
  0.00
  %
  **
  
  **Propylene
  
  **
  
  0.00
  %
  **
  
  **
  
  **
  
  0.00
  %
  **
  
  **Iso Butane
  
  **
  
  0.00
  %
  **
  
  **
  
  **
  
  0.00
  %
  **
  
  **Normal Butane
  
  **
  
  0.00
  %
  **
  
  **
  
  **
  
  0.00
  %
  **
  
  **Iso Pentanes
  
  **
  
  0.00
  %
  **
  
  **
  
  **
  
  0.00
  %
  **
  
  **Normal Pentanes
  
  **
  
  0.00
  %
  **
  
  **
  
  **
  
  0.00
  %
  **
  
  **Hexanes
  
  **
  
  0.00
  %
  **
  
  **
  
  **
  
  0.00
  %
  **
  
  **Total
  
  **
  
  0.00
  %
  **
  
  **
  
  **
  
  0.00
  %
  **
  
  **Volume:Mcfs @ 14.65
  
  **
  
  
  
  
  
  
  
  **Mmbtus
  
  **
  
  
  
  
  
  
  
  **Btu Wet
  
  **
  
  
  
  
  
  
  
  **Dry
  
  **
  
  
  
  
  
  
  
  **Pro-Rata Share of Inlet
  Gas Mcfs**
  
  
  
  
  
  
  
  **CombinedVolume:Mcfs @ 14.65
  
  **Mmbtus
  
  **Pro-Rata Share of Inlet
  Gas Mcfs
  
  
  
  
  
  
  
  
  
  ** 
 * All volumes and amounts are fictional and intended for this example
only.


EXHIBIT
B  Plant Allocation
Statement Statement 2 of Exhibit B  Statement 2  Javelina Plant Allocation Plant Thermal Reduction
"PTR" Month, Year  MmbtusResidue Gas:Theoretical Residue Gas
  Attributable to Supplier's Off-Gas
  
  **Total Quantity of
  Theoretical Residue Gas for all Inlet Gas
  
  **Ratio of Supplier's
  Theoretical Residue Gas
  
  **Actual Residue Gas
  attributable to All Inlet Gas
  
  **Residue Gas Attributable
  to Supplier's Off-Gas
  
  **Plant Thermal Reduction
  "PTR"Inlet 441-207 and Inlet
  441-200
  
  **Residue Gas Attributable
  to Supplier's Off-Gas
  
  **Refiner's Plant Thermal
  Reduction PTR
  
  ** 
 * All volumes and amounts are fictional and intended for this example
only.


EXHIBIT B  Plant Allocation
Statement Statement 3 of Exhibit B  Statement 3  Javelina Plant Allocation Residue Gas Imbalance Month, Year  MmbtusAllocated Residue
  
  **Delivered Residue
  
  **Cumulative Balance Due
  Refinery/(Javelina) prior to settlement
  
  **Imbalance Settlement
  
  **Balance Due Refinery/(Javelina)
  after settlement
  
  **Settlement/Imbalance:
  
  **Mmbtus
  
  **Price
  
  **Balance Due Refinery/(Javelina)
  after settlementExcess Gas Purchase/SaleMmbtus
  
  **Price
  
  **Balance Due Refinery/(Javelina)
  after settlement
  
  ** 
 * All volumes and amounts are fictional and intended for this example
only.


EXHIBIT B  Plant Allocation
Statement Statement 4 of Exhibit B  Statement 4  Javelina Plant Allocation Energy Expense Charge Month, Year  Electricity Cost
  **Plant Fuel Cost
  **Energy Expense
  **Pro-Rata Share of Inlet
  Gas Mcfs
  **Energy Expense Charge
  **
 
 * All volumes and amounts are fictional and intended for this example
only.


EXHIBIT B  Plant Allocation
Statement Statement 5 of Exhibit B  Statement 5  Javelina Plant Allocation Plant Net Proceeds Attributable
to Supplier by Refinery and Credit(s) due Processor on
Curtailments Month, Year  East
  Refinery
  
  West
  Refinery
  
  TotalWeighted
  
  
  
  
  
  WeightedUnit of
  
  
  
  Average
  
  
  
  
  
  AveragePlant Products
  
  Measure
  
  Volume
  
  Sales
  Price
  
  Value
  
  Volume
  
  Sales
  Price
  
  Value
  
  ValueEthylene
  
  Pounds
  
  **
  
  **
  
  **
  
  **
  
  **
  
  **
  
  **Propylene
  
  Pounds
  
  **
  
  **
  
  **
  
  **
  
  **
  
  **
  
  **Ethane
  
  Gallons
  
  **
  
  **
  
  **
  
  **
  
  **
  
  **
  
  **Propane
  
  Gallons
  
  **
  
  **
  
  **
  
  **
  
  **
  
  **
  
  **Iso-Butane
  
  Gallons
  
  **
  
  **
  
  **
  
  **
  
  **
  
  **
  
  **Normal Butane
  
  Gallons
  
  **
  
  **
  
  **
  
  **
  
  **
  
  **
  
  **Pentanes Plus
  
  Gallons
  
  **
  
  **
  
  **
  
  **
  
  **
  
  **
  
  **Hydrogen
  
  Mmbtus
  
  **
  
  **
  
  **
  
  **
  
  **
  
  **
  
  **Plant
  Net Proceeds Attributable to Supplier
  
  
  
  
  
  **
  
  
  
  
  
  **
  
  **Inlet Mcf
  
  
  
  
  
  
  
  **
  
  
  
  
  
  **
  
  **Monthly Average $ per Mcf
  
  
  
  
  
  
  
  **
  
  
  
  
  
  **
  
  **Supplier's East
  less West Monthly Average $ per Mcf
  
  
  
  
  
  
  
  **Volume of Mcf's
  cutback from East rather than West
  
  
  
  
  
  
  
  **Value Loss of Cutting Back
  
  
  
  
  
  
  
  **Processor's POP %
  
  
  
  
  
  
  
  **Credit due Processor for Supplier's Preferential
  Curtailment
  
  
  
  
  **Processor's Economic Loss due to Supplier's
  Curtailment of Off-Gas as defined in Section 3.2 of Gas Processing AgreementPlant Net Proceeds Attributable to Supplier
  
  
  
  
  
  
  
  **
  
  
  
  
  
  **Inlet Mcf
  
  
  
  
  
  
  
  **
  
  
  
  
  
  **Monthly Average $ per Mcf
  
  
  
  
  
  
  
  **
  
  
  
  
  
  **Mcfs Curtailed
  
  
  
  
  
  
  
  **
  
  
  
  
  
  **Processor's POP %
  
  
  
  
  
  
  
  **
  
  
  
  
  
  **Processor's Economic Loss due to Supplier's
  Curtailment of Off-Gas
  
  
  **
  
  
  
  
  
  **
  
  ** 
 * All volumes
and amounts are fictional and intended for this example only.


EXHIBIT B  Plant Allocation
Statement Statement 6 of Exhibit B  Statement 6  Javelina Plant Allocation Supplier Proceeds Calculation Month, Year  Plant Net Proceeds
  Attributable to Supplier's Off-Gas
  **Energy Expense Charge
  **Supplier's Net Proceeds
  **Supplier's Proceeds
  **Gas Imbalance Settlement
  **Excess Gas Purchase/Sale
  **Credit due Processor for
  Supplier's Preferential Curtailment
  **Processor's Economic Loss
  from Supplier Curtailment (Section 3.2)
  **Total Payment Due Supplier
  (Processor)
  ** 
 * All volumes and amounts are fictional and intended for this example
only.