POA DOCUMENT

LIMITED POWER OF ATTORNEY FOR
SECTION 16 REPORTING OBLIGATIONS

POWER
OF ATTORNEY
(LIMITED)


KNOW ALL MEN BY THESE PRESENTS, that I, BEN
A. GUILL of Houston, County of Harris, State of Texas, reposing special
trust and confidence in ANNE E. GOLD, of the Town of Rye, County of
Westchester, State of New York, have made, constituted and appointed, and
by these presents do make, constitute and appoint the said ANNE E. GOLD my
true and lawful attorney-in-fact and agent, both FOR ME PERSONALLY and in
my name, place and stead, IN MY CAPACITY AS AN OFFICER OF FIRST RESERVE
CORPORATION ("FRC"), FIRST RESERVE GP IX, INC. ("GP IX"), FIRST RESERVE GP
X, INC. ("GP X"), or any entity of which any the foregoing is the direct or
indirect general partner or for which any of the foregoing otherwise has
the authority to act (collectively with FRC, GP IX and GP X, the "First
Reserve Entities"), with full power and authority to do and perform each
and every act necessary, as fully as I might do if personally present, to
accomplish and complete the following acts or transactions:

1. With
respect to any entity in which any First Reserve Entity has an investment
(each a "Company"), sign on my behalf, any and all filings (including
filings with the Securities and Exchange Commission), agreements, notices
or documents arising from, or related to any Company, including, (a) any
holdings or investments of any First Reserve Entity in any Company; and (b)
any holdings or investments of mine in any Company.

2. Seek or
obtain, as my representative and on my behalf, from any third party,
including brokers, employee benefit plan administrators and trustees,
information on transactions involving any Company or the securities of any
Company, and I hereby authorize any such person to release any such
information to the attorney-in-fact designated hereunder and approve and
ratify any such release of information; and

3. Perform any and all
other acts which in the discretion of such attorney-in-fact are necessary
or desirable for and on my behalf in connection with the foregoing.

I
acknowledge that:

(a) this Power of Attorney authorizes, but does not
require, such attorney-in-fact to act in his discretion on information
provided to such attorney-in-fact without independent verification of such
information;

(b) any documents prepared and/or executed by such
attorney-in-fact on my behalf pursuant to this Power of Attorney will be in
such form and will contain such information and disclosure as such
attorney-in-fact, in his or her discretion, deems necessary or desirable;


(c) neither such attorney-in-fact nor any Company assumes (i) any
liability for my responsibility to comply with the requirements of any law
or regulation, including without limitation the Securities Act of 1933, as
amended (the "Securities Act") or the Exchange Act of 1934, as amended (the
"Exchange Act"), or (ii) any liability of mine for any failure to comply
with such requirements; and

(d) this Power of Attorney does not
relieve me from responsibility for compliance with my obligations under any
law or regulation, including without limitation the requirements under the
Securities Act and the Exchange Act.

I hereby give and grant ANNE E.
GOLD, in the capacity set forth above, full power and authority to do and
perform all and every act and thing whatsoever requisite, necessary or
appropriate to be done in and about the foregoing matters as fully to all
intents and purposes as I might or could do if present, hereby ratifying
all that such attorney-in-fact of, for and on my behalf, shall lawfully do
or cause to be done by virtue of this Power of Attorney.

This POWER OF
ATTORNEY shall remain in effect until revoked and shall not be affected by
disability of the Principal.

EXECUTED this 17 day of March, 2005.



/s/ BEN A. GUILL

STATE OF TEXAS )
)SS.
COUNTY OF
HARRIS )

The foregoing instrument was acknowledged before me this 17
day of March, 2005, by BEN A. GUILL, the Principal.

Witness my hand
and official seal: /s/ TINA T. SNOWDEN

My commission expires:
October 17, 2005



/s/ ANNE E. GOLD
Specimen Signature of Agent
(Attorney)