Document:

Table of Contents

THIRD
WAIVER TO CREDIT AGREEMENT

THIRD WAIVER TO CREDIT AGREEMENT
(this ‘‘Third Waiver’’),
dated as of September  27,  2006, among QUANTA CAPITAL
HOLDINGS LTD., an exempted company organized under the laws of Bermuda
(the ‘‘Company’’), the
Designated Subsidiary Borrowers (as defined in the Credit Agreement
referred to below) party to the Credit Agreement referred to below, the
undersigned lenders party to the Credit Agreement referred to below,
and JPMORGAN CHASE BANK, N.A. (f/k/a JPMorgan Chase Bank), as
Administrative Agent (in such capacity, the
‘‘Administrative Agent’’).
Unless otherwise defined herein, all capitalized terms used herein and
defined in the Credit Agreement are used herein as therein
defined.

WITNESSETH:

WHEREAS,
the Company, the Designated Subsidiary Borrowers, the lenders from time
to time party thereto (the
‘‘Lenders’’), the
Administrative Agent, and BNP Paribas, Calyon, New York Branch,
Comerica Bank and Deutsche Bank AG New York Branch, as Co-Documentation
Agents (in such capacity, the
‘‘Co-Documentation Agents’’)
have entered into a Credit Agreement, dated as of July
13,  2004 and amended and restated as of July  11,
2005 (as amended, modified or supplemented to, but not including, the
date hereof, the ‘‘Credit
Agreement’’);

WHEREAS, the Company, the
Designated Subsidiary Borrowers, certain Lenders and the Administrative
Agent have entered into a First Amendment and Waiver to the Credit
Agreement, dated as of July  6,  2006 (the
‘‘First Amendment and
Waiver’’);

WHEREAS, the Company, the
Designated Subsidiary Borrowers, certain Lenders and the Administrative
Agent have entered into a Second Waiver to the Credit Agreement, dated
as of August  11,  2006 (the ‘‘Second
Waiver’’); and

WHEREAS, subject to the
terms and conditions set forth below, the parties hereto wish to amend,
modify and/or waive certain provisions of the Credit Agreement as
provided herein;

NOW, THEREFORE, it is
agreed;

		
	I. 	Temporary Amendments and
Waivers

1.    The parties hereto agree that the Waiver
Period (as defined in the First Amendment and Waiver) shall be extended
to and including October  27,  2006.

2.    The
parties hereto hereby agree that so long as all conditions precedent
set forth in Section 5.02 of the Credit Agreement are satisfied at the
time of each issuance or increase, new Letters of Credit shall be
permitted to be issued and increases to the Stated Amount of existing
Letters of Credit shall be permitted, in each case during the Waiver
Period (as extended by this Third Waiver); provided that,
notwithstanding anything to the contrary contained herein or in any
Credit Document, without the prior written consent of the Required
Lenders, (i) such new Letters of Credit and increases to the Stated
Amount of existing Letters of Credit (including those effected pursuant
to the First Amendment and Waiver and/or the Second Waiver) shall be
limited to those scheduled on Annex A to the First Amendment and Waiver
and such other new Letters of Credit and increases to existing Letters
of Credit the aggregate amount of which does not exceed $2,372,522.68
(for an aggregate of $7,500,000.00), (ii) except as provided in clause
(i) above, no other Letters of Credit may be issued and the Stated
Amount of any other existing Letters of Credit may not be increased,
(iii) no Loans may be incurred and (iv) at the time of the issuance of
any such new Letter of Credit or any such increase to an existing
Letter of Credit (including those effected pursuant to the First
Amendment and Waiver and/or the Second Waiver), the respective
Designated Subsidiary Borrower shall deliver to the Collateral Agent
for credit to a segregated sub-account of such Designated Subsidiary
Borrower’s Collateral Account, and shall at all times thereafter
maintain in such 

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sub-account, an amount of cash and Eligible
Securities having a Borrowing Base value (determined as provided in the
definition of ‘‘Advance
Rate’’ contained in the Credit Agreement) equal
to the Stated Amount of such new Letter of Credit or the increase to
the Stated Amount of such existing Letter of
Credit.

3.    Notwithstanding anything to the contrary
contained in the First Amendment and Waiver, the Second Waiver, this
Third Waiver or in the Credit Documents, no Collateral shall be
released to any Designated Subsidiary Borrower without the prior
written consent of the Required Lenders (or all Lenders to the extent
required under the terms of the Credit
Documents).

4.    Notwithstanding anything to the contrary
contained in the First Amendment and Waiver, the Second Waiver, this
Third Waiver or in the Credit Documents, the Company may not pay any
Dividends to the holders of its Series A Preferred Shares during the
Waiver Period.

5.    The parties hereto agree that all
amendments and waivers to the Credit Agreement contained in Article II
of the First Amendment and Waiver, Article I of the Second Waiver and
Article I of this Third Waiver shall terminate and be of no further
force and effect following the Waiver Period (as extended by this Third
Waiver).

		
	II. 	Miscellaneous
Provisions

1.    The Company hereby agrees to pay to
each Lender which executes and delivers to the Administrative Agent a
counterpart hereof (including by way of facsimile (or other electronic)
transmission) by 5:00 p.m. (New York time) on September
27,  2006, a non-refundable cash fee (the
‘‘Waiver Fee’’) in an amount
equal to 0.075% of such Lender’s Commitment as same is in
effect on the Third Waiver Effective Date (as defined below). The
Waiver Fee shall be due and payable on the Third Waiver Effective Date
(and only payable so long as the Third Waiver Effective Date occurs)
and shall be paid by the Company to the Administrative Agent for
distribution to the Lenders entitled thereto.

2.    In order
to induce the Lenders to enter into this Third Waiver, each of the
Company and each Designated Subsidiary Borrower hereby represents and
warrants to the Administrative Agent and each Lender that (i) all of
the representations and warranties contained in the Credit Agreement
and in the other Credit Documents are true and correct in all material
respects on and as of the Third Waiver Effective Date after giving
effect to this Third Waiver (unless such representations and warranties
relate to a specific earlier date, in which case such representations
and warranties shall be true and correct in all material respects as of
such earlier date) and (ii) there exists no Default or Event of Default
as of the Third Waiver Effective Date, after giving effect to this
Third Waiver.

3.    This Third Waiver is limited as specified
and shall not constitute a modification, acceptance or waiver of any
other provision of the Credit Agreement or any other Credit
Document.

4.    This Third Waiver may be executed in any
number of counterparts and by the different parties hereto on separate
counterparts, each of which counterparts when executed and delivered
shall be an original, but all of which shall together constitute one
and the same instrument. Delivery of an executed signature page of this
Third Waiver by facsimile (or other electronic) transmission shall be
effective as delivery of a manually executed counterpart hereof. A
complete set of counterparts executed by all the parties hereto shall
be lodged with the Company and the Administrative
Agent.

5.    THIS THIRD WAIVER AND THE RIGHTS AND
OBLIGATIONS OF THE PARTIES HEREUNDER SHALL BE CONSTRUED IN ACCORDANCE
WITH AND GOVERNED BY THE LAW OF THE STATE OF NEW
YORK.

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6.    This Third Waiver shall become
effective on the date (the ‘‘Third Waiver
Effective Date’’) when (i) the Company, the
Designated Subsidiary Borrowers and the Required Lenders shall have
signed a counterpart hereof (whether the same or different
counterparts) and shall have delivered (including by way of facsimile
(or other electronic) transmission) the same to the Administrative
Agent, c/o White & Case LLP, 1155 Avenue of the Americas, New York,
NY 10036, Attention: May Yip-Daniels (Facsimile No. 212-354-8113;
myip@whitecase.com), (ii) the Company shall have paid the Waiver
Fee as provided in Section II(1) above and (iii) the Company shall have
paid all outstanding costs and expenses of the Administrative Agent in
connection with the Credit Agreement and this Third Waiver (including,
without limitation, all costs and expenses of counsel to the
Administrative Agent in connection therewith and
herewith).

7.    From and after the Third Waiver Effective
Date (but subject to Section I(5) hereof), all references in the Credit
Agreement and in the other Credit Documents to the Credit Agreement
shall be deemed to be a reference to the Credit Agreement as modified
hereby. This Third Waiver shall constitute a Credit Document for all
purposes under the Credit Agreement and the other Credit
Documents.

*    *    *

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IN WITNESS WHEREOF, the undersigned have
caused this Third Waiver to be duly executed and delivered as of the
date first above written.

		QUANTA CAPITAL
HOLDINGS LTD.

			
		By: 	/s/
Jonathan J.R.
Dodd                            

		Name:
Jonathan J.R. Dodd
Title:    Chief Financial
Officer

		QUANTA REINSURANCE
LTD.

			
		By: 	/s/ Jonathan
J.R.
Dodd                            

		Name:
Jonathan J.R. Dodd
Title:    Chief Financial
Officer

		QUANTA U.S. HOLDINGS
INC.

			
		By: 	/s/ Jonathan
J.R.
Dodd                            

		Name:
Jonathan J.R. Dodd
Title:    Chief Financial
Officer

		QUANTA REINSURANCE U.S.
LTD.

			
		By: 	/s/ Jonathan
J.R.
Dodd                            

		Name:
Jonathan J.R. Dodd
Title:    Chief Financial
Officer

		QUANTA INDEMNITY
COMPANY

			
		By: 	/s/ Jonathan
J.R.
Dodd                            

		Name:
Jonathan J.R. Dodd
Title:    Chief Financial
Officer

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		JPMORGAN CHASE BANK,
N.A.,

Individually and as Administrative
Agent

		By: /s/ Heather
Lindstrom                                

		Name:
Heather Lindstrom
Title:    Vice President

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		BNP
PARIBAS

		By: /s/ Laurent
Vanderzyppe                        

		Name:
Laurent Vanderzyppe
Title:    Managing
Director

		By: /s/ Barry S.
Feigenbaum                        

		Name:
Barry S. Feigenbaum
Title:    Managing
Director

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		CALYON, NEW YORK
BRANCH

		By: /s/ Charles
Kornberger            
        

		Name: Charles
Kornberger
Title:    Managing Director

		By:
/s/ William S.
Denton                        

		Name:
William S. Denton
Title:    Managing
Director

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		COMERICA
BANK

		By: /s/ Chatphet
Saipetch                        

		Name:
Chatphet Saipetch
Title:    Vice President

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		BARCLAYS BANK
PLC

		By: /s/ Arthur J.
Olsen                            

		Name:
Arthur J. Olsen
Title:    Director

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		ING BANK N.V. – LONDON
BRANCH

		By: /s/ N.J.
Marchant                        
                

		Name: N.J.
Marchant
Title:    Director

		By: /s/
M.E.R.
Sharman                                    

		Name:
M.E.R. Sharman
Title:    Managing Director

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		DEUTSCHE BANK AG NEW YORK
BRANCH

		By:
                                                                                

		Name:
Title:

		By:
                                                                                

		Name:
Title:FOURTH AMENDMENT TO
                               -------------------
                     REVOLVING CREDIT AND SECURITY AGREEMENT
                     ---------------------------------------

         THIS FOURTH AMENDMENT TO REVOLVING CREDIT AND SECURITY AGREEMENT (this
"Amendment") is made and entered into effective as of the 27th day of September,
2006 (the "Effective Date"), by and between UNION DRILLING, INC., a corporation
organized under the laws of the State of Delaware ("Union Drilling"), THORNTON
DRILLING COMPANY, a corporation originally organized under the laws of the
Delaware, and successor to Thornton Drilling Company, a corporation organized
under the laws of the State of Colorado ("Thornton"), and UNION DRILLING TEXAS,
LP, a Texas limited partnership ("UDT") (Union Drilling, Thornton and UDT,
individually and collectively, jointly and severally, "Borrower" and/or
"Borrowers"), PNC BANK, NATIONAL ASSOCIATION ("PNC"), as agent for the financial
institutions (collectively "Lenders" and each a "Lender"), which are now or
which hereafter become a party to the Credit Agreement (defined below) (PNC, in
such capacity, "Agent") and Lenders.

                             PRELIMINARY STATEMENTS

         A    Borrower, Lenders and Agent are parties to that certain Revolving
Credit and Security Agreement dated March 31, 2005 (as amended, supplemented or
modified from time to time, the "Credit Agreement"); and

         B    Borrower, Lenders and Agent desire to amend the Credit Agreement
and the Other Documents (as defined in the Credit Agreement, as amended hereby)
and Agent and Lenders are willing to do so subject to the terms and conditions
set forth herein.

         NOW, THEREFORE, in consideration of the premises herein contained and
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the parties, intending to be legally bound, agree as
follows:

                                    ARTICLE I
                                   DEFINITIONS
                                   -----------

         1.01 Capitalized terms used in this Amendment are defined in the Credit
Agreement, as amended hereby, unless otherwise stated.

                                   ARTICLE II
                                    AMENDMENT
                                    ---------

         2.01 AMENDMENT TO SUBSECTION 2.1(A)(II). Effective as of the date
hereof, Subsection 2.1(a)(ii) of the Credit Agreement is hereby amended and
restated in its entirety as follows:

              "(ii) (1) up to 75%, subject to the provisions of Section
         2.1(b) hereof, of the Forced Liquidation Value of the Eligible Rig
         Fleet Equipment and (2) up to 60%, subject to the provisions of Section
         2.1(b) hereof, of the acquisition costs of the Rig Fleet Equipment not
         categorized in the most recent FLV Appraisal but acquired after the
         most recent FLV Appraisal, so long as such Rig Fleet

         Equipment satisfies the definition of Eligible Rig Fleet Equipment in
         all other respects ("Rig Fleet Advance Rate" and together with the
         Receivables Advance Rate, collectively, the "Advance Rates"); minus

         2.02 AMENDMENT TO SECTION 7.6. Effective as of the date hereof, Section
7.6 of the Credit Agreement is hereby amended and restated in its entirety as
follows:

              "7.6 Capital Expenditures. Contract for, purchase or make any
         expenditure or commitments for Net Capital Expenditures in any fiscal
         year in an aggregate amount for all Borrowers in excess of $125,000,000
         for fiscal year 2006 and $10,000,000 for each fiscal year thereafter,
         provided, however, (i) the annual allowance for the fiscal year 2007
         and each fiscal year thereafter may be increased by the amount of
         Permitted Equity Issuance Proceeds for such fiscal year, to the extent
         not expended upon Permitted Acquisitions not constituting Capital
         Expenditures and (ii) the annual allowance that is unused during any
         applicable fiscal year may be carried over and used in the immediately
         following fiscal year"

                                  ARTICLE III
                              CONDITIONS PRECEDENT
                              --------------------

         3.01 CONDITIONS TO EFFECTIVENESS. The effectiveness of this Amendment
is subject to the satisfaction of the following conditions precedent, unless
specifically waived in writing by Agent:

              (a)   Agent shall have received this Amendment duly executed by
         Borrowers, in form and substance satisfactory to Agent and its legal
         counsel.

              (b)   The representations and warranties contained herein and in
         the Credit Agreement and the Other Documents, as each is amended
         hereby, shall be true and correct as of the date hereof, as if made on
         the date hereof;

              (c)   No Default or Event of Default shall have occurred and be
         continuing, unless such Default or Event of Default has been
         specifically waived in writing by Agent and Lenders; and

              (d)   All corporate proceedings taken in connection with the
         transactions contemplated by this Amendment and all documents,
         instruments and other legal matters incident thereto shall be
         satisfactory to Agent and its legal counsel and Borrower shall deliver
         to Agent a Secretary's Certificate, in form and substance satisfactory
         to Agent evidencing the same.

                                   ARTICLE IV
                                    NO WAIVER
                                    ---------

         4.01 NO WAIVER. Nothing contained in this Amendment shall be construed
as a waiver by Agent or Lenders of any covenant or provision of the Credit
Agreement, the Other Documents, this Amendment, or of any other contract or
instrument among Borrowers, Agent

                                      -2-

and Lenders, and the failure of Agent and/or Lenders at any time or times
hereafter to require strict performance by Borrower of any provision thereof
shall not waive, affect or diminish any right of Agent and Lenders to thereafter
demand strict compliance therewith. Agent and Lenders hereby reserve all rights
granted under the Credit Agreement, the Other Documents, this Amendment and any
other contract or instrument among Borrowers, Lenders and Agent.

                                   ARTICLE V
                  RATIFICATIONS, REPRESENTATIONS AND WARRANTIES
                  ---------------------------------------------

         5.01 RATIFICATIONS. The terms and provisions set forth in this
Amendment shall modify and supersede all inconsistent terms and provisions set
forth in the Credit Agreement and the Other Documents, and, except as expressly
modified and superseded by this Amendment, the terms and provisions of the
Credit Agreement and the Other Documents are ratified and confirmed and shall
continue in full force and effect. Each Borrower, Lenders and Agent agree that
the Credit Agreement and the Other Documents, as amended hereby, shall continue
to be legal, valid, binding and enforceable in accordance with their respective
terms.

         5.02 REPRESENTATIONS AND WARRANTIES. Each Borrower hereby represents
and warrants to Agent and Lenders that (a) the execution, delivery and
performance of this Amendment and any and all Other Documents executed and/or
delivered in connection herewith have been authorized by all requisite corporate
action on the part of such Borrower and will not violate the Articles of
Incorporation or Bylaws or other organization documents or governing documents
of such Borrower; (b) the representations and warranties contained in the Credit
Agreement, as amended hereby, and the Other Documents are true and correct on
and as of the date hereof and on and as of the date of execution hereof as
though made on and as of each such date; (c) no Default or Event of Default
under the Credit Agreement, as amended hereby, has occurred and is continuing,
unless such Default or Event of Default has been specifically waived in writing
by Agent and Lenders; (d) each Borrower is in full compliance with all covenants
and agreements contained in the Credit Agreement and the Other Documents, as
amended hereby; and (e) each Borrower has not amended its Articles of
Incorporation or its Bylaws or other organization or governing documents since
the date of the Credit Agreement.

                                   ARTICLE VI
                            MISCELLANEOUS PROVISIONS
                            ------------------------

         6.01 SURVIVAL OF REPRESENTATIONS AND WARRANTIES. All representations
and warranties made in the Loan Agreement or the Other Documents, including,
without limitation, any document furnished in connection with this Amendment,
shall survive the execution and delivery of this Amendment and the Other
Documents, and no investigation by Agent or any closing shall affect the
representations and warranties or the right of Agent and Lenders to rely upon
them.

         6.02 REFERENCE TO CREDIT AGREEMENT. Each of the Credit Agreement and
the Other Documents, and any and all other agreements, documents or instruments
now or hereafter executed and delivered pursuant to the terms hereof or pursuant
to the terms of the Credit Agreement, as amended hereby, are hereby amended so
that any reference in the Credit

                                      -3-

Agreement and such Other Documents to the Credit Agreement shall mean a
reference to the Credit Agreement as amended hereby.

         6.03 EXPENSES OF AGENT. Each Borrower agrees to pay on demand all
reasonable costs and expenses incurred by Agent and Lenders in connection with
any and all amendments, modifications, and supplements to the Other Documents,
including, without limitation, the costs and fees of Agent's legal counsel, and
all costs and expenses incurred by Agent in connection with the enforcement or
preservation of any rights under the Credit Agreement, as amended hereby, or any
of the Other Documents, including, without, limitation, the costs and fees of
Agent's and Lenders' legal counsel.

         6.04 SEVERABILITY. Any provision of this Amendment held by a court of
competent jurisdiction to be invalid or unenforceable shall not impair or
invalidate the remainder of this Amendment and the effect thereof shall be
confined to the provision so held to be invalid or unenforceable.

         6.05 SUCCESSORS AND ASSIGNS. This Amendment is binding upon and shall
inure to the benefit of Agent, Lenders and each Borrower and their respective
successors and assigns, except that no Borrower may assign or transfer any of
its rights or obligations hereunder without the prior written consent of Agent
and Lenders.

         6.06 COUNTERPARTS. This Amendment may be executed in one or more
counterparts, each of which when so executed shall be deemed to be an original,
but all of which when taken together shall constitute one and the same
instrument.

         6.07 EFFECT OF WAIVER. No consent or waiver, express or implied, by
Agent and/or Lenders to or for any breach of or deviation from any covenant or
condition by any Borrower shall be deemed a consent to or waiver of any other
breach of the same or any other covenant, condition or duty.

         6.08 HEADINGS. The headings, captions, and arrangements used in this
Amendment are for convenience only and shall not affect the interpretation of
this Amendment.

         6.09 APPLICABLE LAW. THIS AMENDMENT AND ALL OTHER AGREEMENTS EXECUTED
PURSUANT HERETO SHALL BE DEEMED TO HAVE BEEN MADE AND TO BE PERFORMABLE IN AND
SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF
NEW YORK.

         6.10 FINAL AGREEMENT. THE CREDIT AGREEMENT AND THE OTHER DOCUMENTS,
EACH AS AMENDED HEREBY, REPRESENT THE ENTIRE EXPRESSION OF THE PARTIES WITH
RESPECT TO THE SUBJECT MATTER HEREOF ON THE DATE THIS AMENDMENT IS EXECUTED. THE
CREDIT AGREEMENT AND THE OTHER DOCUMENTS, AS AMENDED HEREBY, MAY NOT BE
CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS OR SUBSEQUENT ORAL AGREEMENTS
OF THE PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES. NO
MODIFICATION, RESCISSION, WAIVER, RELEASE OR AMENDMENT OF ANY PROVISION OF THIS
AMENDMENT SHALL BE MADE,

                                      -4-

EXCEPT BY A WRITTEN AGREEMENT SIGNED BY BORROWER, LENDERS AND AGENT.

         6.11 RELEASE. EACH BORROWER HEREBY ACKNOWLEDGES THAT IT HAS NO DEFENSE,
COUNTERCLAIM, OFFSET, CROSS-COMPLAINT, CLAIM OR DEMAND OF ANY KIND OR NATURE
WHATSOEVER THAT CAN BE ASSERTED TO REDUCE OR ELIMINATE ALL OR ANY PART OF ITS
LIABILITY TO REPAY ANY LOANS OR EXTENSIONS OF CREDIT FROM LENDERS TO BORROWERS
UNDER THE CREDIT AGREEMENT OR THE OTHER DOCUMENTS OR TO SEEK AFFIRMATIVE RELIEF
OR DAMAGES OF ANY KIND OR NATURE FROM AGENT OR LENDERS WITH RESPECT TO MATTERS
RELATING TO THE CREDIT AGREEMENT OR THE OTHER DOCUMENTS. EACH BORROWER HEREBY
VOLUNTARILY AND KNOWINGLY RELEASES AND FOREVER DISCHARGES AGENT AND LENDERS,
THEIR PREDECESSORS, AGENTS, EMPLOYEES, SUCCESSORS AND ASSIGNS, FROM ALL POSSIBLE
CLAIMS, DEMANDS, ACTIONS, CAUSES OF ACTION, DAMAGES, COSTS, EXPENSES, AND
LIABILITIES WHATSOEVER, KNOWN OR UNKNOWN, ANTICIPATED OR UNANTICIPATED,
SUSPECTED OR UNSUSPECTED, FIXED, CONTINGENT, OR CONDITIONAL, AT LAW OR IN
EQUITY, ORIGINATING IN WHOLE OR IN PART ON OR BEFORE THE DATE THIS AMENDMENT IS
EXECUTED, WHICH BORROWERS MAY NOW OR HEREAFTER HAVE AGAINST AGENT, LENDERS,
THEIR PREDECESSORS, AGENTS, EMPLOYEES, SUCCESSORS AND ASSIGNS, IF ANY, AND
IRRESPECTIVE OF WHETHER ANY SUCH CLAIMS ARISE OUT OF CONTRACT, TORT, VIOLATION
OF LAW OR REGULATIONS, OR OTHERWISE, AND ARISING FROM ANY LOANS OR EXTENSIONS OF
CREDIT FROM LENDERS TO BORROWERS UNDER THE CREDIT AGREEMENT OR THE OTHER
DOCUMENTS, INCLUDING, WITHOUT LIMITATION, ANY CONTRACTING FOR, CHARGING, TAKING,
RESERVING, COLLECTING OR RECEIVING INTEREST IN EXCESS OF THE HIGHEST LAWFUL RATE
APPLICABLE, THE EXERCISE OF ANY RIGHTS AND REMEDIES UNDER THE CREDIT AGREEMENT
OR ANY OF THE OTHER DOCUMENTS, AND NEGOTIATION FOR AND EXECUTION OF THIS
AMENDMENT.

         [Remainder of Page Intentionally Blank; Signature Pages Follow]

                                      -5-

         IN WITNESS WHEREOF, each of the parties hereto has executed this
Amendment as of the date first above-written.

                                   BORROWERS:

                                   UNION DRILLING, INC.

                                   By: /s/ Dan Steigerwald
                                       ----------------------------------------
                                   Name: Dan Steigerwald
                                         --------------------------------------
                                   Title: C.F.O.
                                          -------------------------------------

                                   THORNTON DRILLING COMPANY

                                   By: /s/ Dan Steigerwald
                                       ----------------------------------------
                                   Name: Dan Steigerwald
                                         --------------------------------------
                                   Title: C.F.O.
                                          -------------------------------------

                                   UNION DRILLING TEXAS, LP

                                   By:    Union Drilling Texas GP, LLC, its
                                          general partner

                                   By: /s/ Dan Steigerwald
                                      -----------------------------------------
                                   Name: Dan Steigerwald
                                         --------------------------------------
                                   Title: C.F.O.
                                          -------------------------------------

                                   AGENT AND LENDER:

                                   PNC BANK, NATIONAL ASSOCIATION

                                   By: /s/ Timothy S. Culver
                                      -----------------------------------------
                                   Name: Timothy S. Culver
                                         --------------------------------------
                                   Title: Vice President
                                          -------------------------------------

                                   LENDERS:

                                   M&I BUSINESS CREDIT, INC.
                                   (f/k/a DIVERSIFIED BUSINESS CREDIT, INC.)

                                   By: /s/ Sandra M. Crawford
                                      -----------------------------------------
                                   Name: Sandra M. Crawford
                                         --------------------------------------
                                   Title: Vice President
                                          -------------------------------------

                                   N M ROTHSCHILD & SONS LIMITED

                                   By: /s/ Nicholas Wood
                                      -----------------------------------------
                                   Name: Nicholas Wood
                                         --------------------------------------
                                   Title: Director
                                          -------------------------------------

                                   By: /s/ Derek McCrane
                                      -----------------------------------------
                                   Name: Derek McCrane
                                         --------------------------------------
                                   Title: Assistant Director
                                          -------------------------------------

                                   NATIONAL CITY BANK OF PENNSYLVANIA

                                   By: /s/ Susan J. Dimmick
                                      -----------------------------------------
                                   Name: Susan J. Dimmick
                                         --------------------------------------
                                   Title: Vice President
                                          -------------------------------------

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