<PAGE>
 
                                                              CONTRACT #: 800491
                                                                          ------

                                                                   EXHIBIT 10.39


                               SERVICE AGREEMENT
                             FOR RATE SCHEDULE CDS


     This Service Agreement, made and entered into this 1st day of May, 1996 by
and between TEXAS EASTERN TRANSMISSION CORPORATION, A Delaware Corporation
(herein called "Pipeline") and BOSTON GAS COMPANY (herein called "Customer",
whether one or more),


                             W I T N E S S E T H:


     WHEREAS, Pipeline and Customer are parties to three service agreements
under Rate Schedule CDS (Pipeline's Contract Nos. 800416, 800481 and 800483)
which specify an MDQ of 2,932 dth, 36 dth and 209 dth, respectively; and

     WHEREAS, Pipeline and Customer desire to enter into this Service Agreement
under Rate Schedule CDS which shall supersede the Customer's existing Rate
Schedule CDS service agreements (Pipeline's Contract Nos. 800416, 800481 and
800483);

    NOW, THEREFORE, in consideration of the premises and of the mutual covenants
and agreements herein contained, the parties do covenant and agree as follows:


                                   ARTICLE I

                              SCOPE OF AGREEMENT

     Subject to the terms, conditions and limitations hereof, of Pipeline's Rate
Schedule CDS, and of the General Terms and Conditions, transportation service
hereunder will be firm. Subject to the terms, conditions and limitations hereof
and of Sections 2.3 and 2.4 of Pipeline's Rate Schedule CDS, Pipeline shall
deliver to those points on Pipeline's system as specified In Article IV herein
or available to Customer pursuant to Section 14 of the General Terms and
Conditions (hereinafter referred to as Point(s) of Delivery), for Customer's
account, as requested for any day, natural gas quantities up to Customer's MDQ.
Customer's MDQ is as follows

                    Maximum Daily Quantity (MDQ) 3,177 dth

     Subject to variances as may be permitted by Sections 2.4 of Rate Schedule
CDS or the General Terms and Conditions, Customer shall deliver to Pipeline and
Pipeline shall receive, for Customer's account, at those points on Pipeline's
system as specified in Article IV herein or available to Customer pursuant to
Section 14 of the General Terms and Conditions (hereinafter referred to as
Point(s) of Receipt) daily quantities of gas equal to the daily quantities
delivered to Customer pursuant to this Service Agreement up to Customer's MDQ,
plus Applicable Shrinkage as specified in the General Terms and Conditions.

                                                              
<PAGE>
 
                               SERVICE AGREEMENT
                             FOR RATE SCHEDULE CDS
                                  (Continued)

     Pipeline shall not be obligated to, but may at its discretion, receive at
any Point of Receipt on any day a quantity of gas in excess of the applicable
Maximum Daily Receipt Obligation (MDRO), plus Applicable Shrinkage, but shall
not receive in the aggregate at all Points of Receipt on any day a quantity of
gas in excess of the applicable MDQ, plus Applicable Shrinkage. Pipeline shall
not be obligated to, but may at its discretion, deliver at any Point of Delivery
on any day a quantity of gas in excess of the applicable Maximum Daily Delivery
Obligation (MDDO), but shall not deliver in the aggregate at all Points of
Delivery on any day a quantity of gas in excess of the MDQ.

     In addition to the MDQ and subject to the terms, conditions and limitations
hereof, Rate Schedule CDS and the General Terms and Conditions, Pipeline shall
deliver within the Access Area under this and all other service agreements under
Rate Schedules CDS, FT-1, and/or SCT, quantities up to Customer's Operational
Segment Capacity Entitlements, excluding those Operational Segment Capacity
Entitlements scheduled to meet Customer's MDQ, for Customer's account, as
requested on any day.

                                  ARTICLE II

                               TERM OF AGREEMENT

     The term of this Service Agreement shall commence on the later of March 1,
1996, or the first day of the first month following execution of this Service
Agreement by Customer, and shall continue in force and effect until October 31,
2012 and year to year thereafter unless this Service Agreement is terminated as
hereinafter provided. This Service Agreement may be terminated by either
Pipeline or Customer upon five (5) years prior written notice to the other
specifying a termination date of any October 31 of any year occurring on or
after the expiration of the primary term. Subject to Section 22 of Pipeline's
General Terms and Conditions and without prejudice to such rights, this Service
Agreement may be terminated at any time by Pipeline in the event Customer fails
to pay part or all of the amount of any bill for service hereunder and such
failure continues for thirty (30) days after payment is due; provided, Pipeline
gives thirty (30) days prior written notice to Customer of such termination and
provided further such termination shall not be effective if, prior to the date
of termination, Customer either pays such outstanding bill or furnishes a good
and sufficient surety bond guaranteeing payment to Pipeline of such outstanding
bill.

     THE TERMINATION OF THIS SERVICE AGREEMENT WITH A FIXED CONTRACT TERM OR THE
PROVISION OF A TERMINATION NOTICE BY CUSTOMER TRIGGERS PREGRANTED ABANDONMENT
UNDER SECTION 7 OF THE NATURAL GAS ACT AS OF THE EFFECTIVE DATE OF THE
TERMINATION.

                                       2
<PAGE>
 
                               SERVICE AGREEMENT
                             FOR RATE SCHEDULE CDS
                                  (Continued)

PROVISION OF A TERMINATION NOTICE BY PIPELINE ALSO TRIGGERS CUSTOMER'S RIGHT OF
FIRST REFUSAL UNDER SECTION 3.13 OF THE GENERAL TERMS AND CONDITIONS ON THE
EFFECTIVE DATE OF THE TERMINATION.

     Any portions of this Service Agreement necessary to correct or cash-out
imbalances under this Service Agreement as required by the General Terms and
Conditions of Pipeline's FERC Gas Tariff, Volume No. 1, shall survive the other
parts of this Service Agreement until such time as such balancing has been
accomplished.

                                  ARTICLE III

                                 RATE SCHEDULE

     This Service Agreement in all respects shall be and remain subject to the
applicable provisions of Rate Schedule CDS and of the General Terms and
Conditions of Pipeline's FERC Gas Tariff on file with the Federal Energy
Regulatory Commission, all of which are by this reference made a part hereof.

     Customer shall pay Pipeline, for all services rendered hereunder and for
the availability of such service in the period stated, the applicable prices
established under Pipeline's Rate Schedule CDS as filed with the Federal Energy
Regulatory Commission, and as same may hereafter be legally amended or
superseded.

     Customer agrees that Pipeline shall have the unilateral right to file with
the appropriate regulatory authority and make changes effective in (a) the rates
and charges applicable to service pursuant to Pipeline's Rate Schedule CDS, (b)
Pipeline's Rate Schedule CDS pursuant to which service hereunder is rendered or
(c) any provision of the General Terms and Conditions applicable to Rate
Schedule CDS. Notwithstanding the foregoing, Customer does not agree that
Pipeline shall have the unilateral right without the consent of Customer
subsequent to the execution of this Service Agreement and Pipeline shall not
have the right during the effectiveness of this Service Agreement to make any
filings pursuant to Section 4 of the Natural Gas Act to change the MDQ specified
in Article I, to change the term of the agreement as specified in Article II, to
change Point(s) of Receipt specified in Article IV, to change the Point(s) of
Delivery specified in Article IV, or to change the firm character of the service
hereunder. Pipeline agrees that Customer may protest or contest the
aforementioned filings, and Customer does not waive any rights it may have with
respect to such filings.

                                       3
<PAGE>
 
                               SERVICE AGREEMENT
                             FOR RATE SCHEDULE CDS
                                  (Continued)


                                  ARTICLE IV

                 POINT(S) OF RECEIPT AND POINT(S) OF DELIVERY

     The Point(s) of Receipt and Point(s) of Delivery at which Pipeline shall
receive and deliver gas, respectively, shall be specified in Exhibit(s) A and B
of the executed service agreement. Customer's Zone Boundary Entry Quantity and
Zone Boundary Exit Quantity for each of Pipeline's zones shall be specified in
Exhibit C of the executed service agreement.

     Exhibit(s) A and B are hereby incorporated as part of this Service
Agreement for all intents and purposes as if fully copied and set forth herein
at length.

                                   ARTICLE V

                                    QUALITY

     All natural gas tendered to Pipeline for Customer's account shall conform
to the quality specifications set forth in Section 5 of Pipeline's General Terms
and Conditions. Customer agrees that in the event Customer tenders for service
hereunder and Pipeline agrees to accept natural gas which does not comply with
Pipeline's quality specifications, as expressly provided for in Section 5 of
Pipeline's General Terms and Conditions, Customer shall pay all costs associated
with processing of such gas as necessary to comply with such quality
specifications. Customer shall execute or cause its supplier to execute, if such
supplier has retained processing rights to the gas delivered to Customer, the
appropriate agreements prior to the commencement of service for the
transportation and processing of any liquefiable hydrocarbons and any PVR
quantities associated with the processing of gas received by Pipeline at the
Point(s) of Receipt under such Customer's service agreement. In addition,
subject to the execution of appropriate agreements, Pipeline is willing to
transport liquids associated with the gas produced and tendered for
transportation hereunder.


                                  ARTICLE VI

                                   ADDRESSES

     Except as herein otherwise provided or as provided in the General Terms and
Conditions of Pipeline's FERC Gas Tariff, any notice, request, demand,
statement, bill or payment provided for in this Service Agreement, or any notice
which any party may desire to give to the other, shall be in writing and shall
be considered as duly delivered when mailed by registered, certified, or regular
mail to the post office address of the parties hereto, as the case may be, as
follows:

                                       4
<PAGE>
 
                               SERVICE AGREEMENT
                             FOR RATE SCHEDULE CDS
                                  (Continued)

     (a)  Pipeline:   TEXAS EASTERN TRANSMISSION CORPORATION
                      5400 Westheimer Court
                      Houston, TX  77056-5310

     (b)  Customer:   BOSTON GAS COMPANY
                      One Beacon Street
                      Boston, MA  02108

or such other address as either party shall designate by formal written notice.


                                  ARTICLE VII

                                  ASSIGNMENTS

     Any Company which shall succeed by purchase, merger, or consolidation to
the properties, substantially as an entirety, of Customer, or of Pipeline, as
the case may be, shall be entitled to the rights and shall be subject to the
obligations of its predecessor in title under this Service Agreement; and either
Customer or Pipeline may assign or pledge this Service, Agreement under the
provisions of any mortgage, deed of trust, indenture, bank credit agreement,
assignment, receivable sale, or similar instrument which it has executed or may
execute hereafter; otherwise, neither Customer nor Pipeline shall assign this
Service Agreement or any of its rights hereunder unless it first shall have
obtained the consent thereto in writing of the other; provided further, however,
that neither Customer nor Pipeline shall be released from its obligations
hereunder without the consent of the other. In addition, Customer may assign its
rights to capacity pursuant to Section 3.14 of the General Terms and Conditions.
To the extent Customer so desires, when it releases capacity pursuant to Section
3.14 of the General Terms and Conditions, Customer may require privity between
Customer and the Replacement Customer, as further provided in the applicable
Capacity Release Umbrella Agreement.


                                 ARTICLE VIII

                                INTERPRETATION

     The interpretation and performance of this Service Agreement shall be in
accordance with the laws of the State of Texas without recourse to the law
governing conflict of laws.

     This Service Agreement and the obligations of the parties are subject to
all present and future valid laws with respect to the subject matter, State and
Federal, and to all valid present and future orders, rules, and regulations of
duly constituted authorities having jurisdiction.

                                       5
<PAGE>
 
                               SERVICE AGREEMENT
                             FOR RATE SCHEDULE CDS
                                  (Continued)
                                        

                                  ARTICLE IX
                                        
                       CANCELLATION OF PRIOR CONTRACT(S)

     This Service Agreement supersedes and cancels, as of the effective date of
this Service Agreement, the contract(s) between the parties hereto as described
below:

     Service Agreement(s) dated, November 7, 1994, October 21, 1994 and
     October 25, 1994 between Pipeline and Customer under Pipeline's Rate
     Schedule CDS (Pipline's Contract Nos, 800416, 800481 and 800483).

                                       6
<PAGE>
 
                               SERVICE AGREEMENT
                             FOR RATE SCHEDULE CDS
                                  (Continued)
                                        
     IN WITNESS WHEREOF, the parties hereto have caused this Service Agreement
to be signed by their respective Presidents, Vice Presidents or other duly
authorized agents and their respective corporate seals to be hereto affixed and
attested by their respective Secretaries or Assistant Secretaries, the day and
year first above written.

                                         TEXAS EASTERN TRANSMISSION CORPORATION


                                         BY /s/ Robert B. Evans
                                           ------------------------------------
                                                    Vice President



ATTEST:

/s/ Robert W. Reed
------------------
  ROBERT W. REED
CORPORATE SECRETARY


                                         BOSTON GAS COMPANY


                                         By /s/ W. R. Luthern
                                           ------------------------------------ 

ATTEST:

/s/ Diane M. O'Brien, Notary
--------------------------------
My Commission Expires 11/23/01

                                       7
<PAGE>
 
                                                              CONTRACT #: 800491
                                                                          ------
 

                        EXHIBIT A, TRANSPORTATION PATHS
                      FOR BILLING PURPOSES, DATED 5/1/96,
               TO THE SERVICE AGREEMENT UNDER RATE SCHEDULE CDS
       BETWEEN TEXAS EASTERN TRANSMISSION CORPORATION ("PIPELINE"), AND
                        BOSTON GAS COMPANY (CUSTOMER"),
                                 DATED 5/1/96:
                                        

(1)  Customer's firm Point(s) of Receipt:

<TABLE> 
<CAPTION> 
                                                   MAXIMUM DAILY             
POINT OF                                        RECEIPT OBLIGATION                  MEASUREMENT  
RECEIPT            DESCRIPTION          (PLUS APPLICABLE SHRINKAGE) (DTH)         RESPONSIBILITIES        OWNER         OPERATOR
--------           -----------          ---------------------------------         ----------------        -----         --------
<S>                <C>                  <C>                                       <C>                     <C>           <C> 
NONE
</TABLE> 
                                  
(2)  Customer shall have Pipeline's Master Receipt Point List ("MRPL"). Customer
     hereby agrees that Pipeline's MRPL as revised and published by Pipeline
     from time to time is incorporated herein by reference.

Customer hereby agrees to comply with the Receipt Pressure Obligation as set
forth in Section 6 of Pipeline's General Terms and Conditions at such Point(s)
of Receipt.

                                                        TRANSPORTATION
                   TRANSPORTATION PATH               PATH QUANTITY (DTH/D)
                   -------------------               ---------------------

                   M3 TO M3                                 3,177


SIGNED FOR IDENTIFICATION

PIPELINE: /s/ Robert B. Evans
         --------------------------

CUSTOMER: /s/ W. R. Luthern
         --------------------------

SUPERSEDES EXHIBIT A DATED:________

                                      A-1
<PAGE>
 
                                                              CONTRACT #: 800491
                                                                          ------


                EXHIBIT B, POINT(S) OF DELIVERY, DATED 5/1/96,
               TO THE SERVICE AGREEMENT UNDER RATE SCHEDULE CDS
       BETWEEN TEXAS EASTERN TRANSMISSION CORPORATION ("Pipeline"), AND
                       BOSTON GAS COMPANY ("Customer"),
                                 DATED 5/1/96:
 
<TABLE> 
<CAPTION>                      
                                                  Maximum                                                                           
                                                  Daily            Delivery                                                         
    Point of                                      Delivery         Pressure         Measurement                                     
    Delivery       Description                    Obligation       Obligation       Responsibilities         Owner        Operator
    ---------      -----------                    ----------       ----------       ----------------         -----        -------- 
                                                     (DTH)
<S>                <C>                            <C>              <C>              <C>                      <C>          <C> 
1.  70087          ALGONQUIN - LAMBERTVILLE,      1,364            AS REQUESTED     TX EAST TRAN             TX EAST      ALGONQUIN
                   NJ HUNTERDON CO., NJ                            BY CUSTOMER,                              TRAN
                                                                   NOT TO
                                                                   EXCEED 750  
                                                                   POUNDS PER 
                                                                   SQUARE INCH
                                                                   GAUGE       

2.  71078          ALGONQUIN - HANOVER, NJ        1,813            AS REQUESTED     TX EAST TRAN             TX EAST      ALGONQUIN 
                   MORRIS CO., NJ                                  BY CUSTOMER,                              TRAN
                                                                   NOT TO     
                                                                   EXCEED 750 
                                                                   POUNDS PER 
                                                                   SQUARE INCH
                                                                   GAUGE

3.  79818          AGT-BOSTON GAS FOR                 0            N/A              N/A                      N/A          N/A
                   NOMINATION PURPOSES
</TABLE> 


provided, however, that until changed by a subsequent Agreement between Pipeline
and Customer, Pipeline's aggregate maximum daily delivery obligations under this
and all other firm Service Agreements existing between Pipeline and Customer,
shall in no event exceed the following:

                                      B-1
<PAGE>
 
                                                              CONTRACT #: 800491
                                                                          ------


                  EXHIBIT B, POINT(S) OF DELIVERY (CONTINUED)
                              BOSTON GAS COMPANY
 
<TABLE> 
<CAPTION>                                         
                                                 AGGREGATE MAXIMUM DAILY
            POINT OF DELIVERY                    DELIVERY OBLIGATION DTH)
            -----------------                    ------------------------ 
            <S>                                  <C> 
                  NO.1                                  199,609

                  No.2                                   75,844
</TABLE> 


SIGNED FOR IDENTIFICATION

PIPELINE: /s/ Robert B. Evans
         -------------------------
        
CUSTOMER: /s/ W. R. Luthern
         -------------------------

SUPERSEDES EXHIBIT B DATED _______

                                      B-2