<PAGE>

                                    EXHIBIT I

                 OFFSITE SERVICES AGREEMENT: PRINCIPAL DOCUMENT

This continuing services agreement ("Agreement") is made effective as of the
date of last signature below, between Exxon Company, U.S.A., a division of Exxon
Corporation, a New Jersey corporation, having offices at 800 Bell Street,
Houston, Texas 77002 ("Exxon") and Asphalt Supply and Services, Incorporated
(ASSI), a Montana corporation, having offices at 509 West Railroad Street,
Laurel, Montana 59044 ("Contractor"). and is made in consideration of the terms
and conditions contained in this Agreement. Exxon and Contractor agree as
follows:

                                      INDEX
<TABLE>
<S>                                                    <C>
I           PRINCIPAL DOCUMENT                         II. GENERAL TERMS AND CONDITIONS

1.          DEFINITIONS
2.          SCOPE OF SERVICES
3.          TERM                                       III. EXHIBITS
4.          VOLUME
5.          COMPENSATION                               Unless indicated by "N/A" adjacent to each Exhibit listed
6.          INVOICING PROCEDURES                       below, the following Exhibits are each incorporated into
7.          CONTRACTOR'S WARRANTIES                    this Agreement.
8.          RETURNED GOODS
9.          HEALTH, SAFETY AND RELATED POLICIES        EXHIBIT A    Scope of Services              -------
10.         ENVIRONMENTAL                              EXHIBIT B    Product Quality Control & Measurement
11.         INSURANCE                                                                              -------
12.         APPLICABLE LAW                             EXHIBIT C    Compatibility & Cleaning Guidelines
13.         FEDERAL CONTRACT CLAUSES                                                               -------
14.         NOTICES                                    EXHIBIT D    Compensation                   -------
15.         SURVIVORSHIP                               EXHIBIT E    Invoicing Procedures           -------
16.         AGREEMENT ASSIGNMENTS                      EXHIBIT F    Federal Contract Supplement    -------
17.         AMENDMENTS                                 EXHIBIT G    Health and Safety Requirements -------
18.         PRECEDENCE
19.         ENTIRE AGREEMENT                           EXHIBIT H    Drug and Alcohol Policy        -------
20.         CONDITION PRECEDENT                        EXHIBIT I    Product Specifications         -------
                                                       EXHIBIT J    Marine Provisions                N/A
                                                                                                   -------
</TABLE>

                              ARTICLE 1: DEFINITIONS

For the purposes of this Agreement, the following terms shall have the meanings
stated below:

<TABLE>
<S>                                                                         <C>
1)                 "Agreement" means this Principal Document, the                Houston, Texas 77002 which is the party entering
                   Exhibits indicated in the Index and the General               into this Agreement.
                   Terms and Conditions.
                                                                            6)   "Law" means all government laws, regulations and
2)                 "Competence" means the expertise, experience,                 rules.
                   capability and specialized knowledge to perform
                   Services in a good and workmanlike manner and            7)   "Principal Document" means this part of this
                   within all accepted standards for the industry.               Agreement labeled CONTINUING SERVICES
                                                                                 AGREEMENT: PRINCIPAL DOCUMENT.
3)                 "Contractor" means the legal entity identified in the
                   preamble of this Principal Document that is              8)   "Product" means asphalt binders and related
                   responsible for performing Services in accordance             additives listed in Exhibit 1.
                   with the terms of this Agreement.
                                                                            9)   "Services" means the services described in Exhibit
4)                 "Exhibits" means the exhibits listed In the Principal         A.
                   Document and incorporated into this Agreement.
                                                                            10)  "Subcontractors" means subcontractors, suppliers
5)                 "Exxon" means Exxon Company, U.S.A., a division               or materialmen providing materials or services to
                   of Exxon Corporation, a New Jersey corporation,               Contractor for the purpose of completing Services
                   having its principal offices at 800 Bell Street,              under this Agreement.
</TABLE>

<PAGE>

                                        Continuing Services Agreement PIA032398

                          ARTICLE 2: SCOPE OF SERVICES

The purpose of this Agreement is to provide the Services specifically set out in
Exhibit A. The Services are generally described as receiving, unloading,
storing, blending, shipping, and inventorying Exxon Product by Contractor at
ASSI's asphalt terminal located at 509 West Railroad Street, Laurel, Montana
59044.

                    ARTICLE 3: TERM AND AGREEMENT TERMINATION

3.1         TERM
The Term of this Agreement begins on the date of last signature below and shall
continue through December 31, 1998, at which time it shall automatically renew
each calendar year thereafter, unless terminated earlier as permitted by this
Agreement. In no event shall this Agreement extend beyond December 31,
2000.

3.2         AGREEMENT TERMINATION
Exxon or Contractor may terminate this Agreement on the last day of an
annual term by giving a notice of termination at least ninety (90) days in
advance to the other party.

Neither party shall be liable to the other as a result of termination of this
Agreement for any costs, claims, losses, damages, or liabilities including,
without limitation, loss of anticipated profits. Exxon shall not be liable to
Contractor for reimbursement for Services unperformed as a result of the
termination.

3.3         PRODUCTS IN CUSTODY AT TERMINATION/EXPIRATION
Upon receipt or delivery of a notice of termination or expiration of this
Agreement, Contractor shall have the option to purchase all or any quantity
of Product in its custody at any termination or expiration of this Agreement,
such option exercisable by giving Exxon notice of its election, including the
quantity of Product to be purchased, not later than thirty (30) days prior to
the effective date of termination. If Contractor exercises its option, title
to the option quantities of the Product shall automatically pass to
Contractor on the date of termination or expiration, and within ten (10) days
thereafter, Contractor shall pay Exxon per an agreed upon price at the time
of termination or expiration. Volume to be determined by gauging the tanks.
If Contractor does not exercise its option, Exxon shall arrange to have all
Product removed from ASSI's facility on or before the date of termination or
expiration at Exxon's expense.

                                ARTICLE 4: VOLUME

Exxon is not committed to purchase any specific amount of Service during the
period covered by this Agreement. Any yearly usage figures are Exxon's best
estimate of requirements and are for Contractor's use as a guide.

                             ARTICLE 5: COMPENSATION

Subject to the provisions of this Agreement, Contractor shall charge and
Exxon shall pay Contractor the applicable rates and fees specified in Exhibit
D, for satisfactory performance and completion of Services that Contractor
performs under this Agreement. No payment by Exxon shall limit Exxon's right
to later dispute any of the charges invoiced, and payment shall not be
construed at Exxon's acceptance of any Services.

                        ARTICLES 6: INVOICING PROCEDURES

Contractor shall invoice Exxon for Services using the invoicing procedures in
Exhibit E. Exxon shall not be obligated to make any payments of invoices if
Contractor does not comply with invoicing procedures.

                       ARTICLE 7: CONTRACTOR'S WARRANTIES

7.1         CONTRACTOR'S REPRESENTATIONS AND WARRANTIES

Contractor represents and warrants that it:
       (a)    Has the Competence to perform the Services;
       (b)    Has or shall obtain the necessary tools, equipment and personnel
              to provide the Services;
       (c)    Shall maintain and use all tools and equipment in accordance with
              manufacturer's specifications and recommendations and good
              engineering and operational practices;
       (d)    Has or shall obtain, at its expense, before performing any
              Services all the necessary certificates, permits, licenses and
              authorizations to conduct business and perform the Services;
       (e)    Shall perform all Services in accordance with all applicable Law;
       (f)    Shall perform all Services in good faith, promptly, with due
              diligence and Competence; and
       (g)    Fully comprehends the requirements and contingencies for providing
              Services and it shall examine the Work Site for any additional or
              special requirements and contingencies prior to performing
              Services.


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                                         Continuing Services Agreement PIA032398

7.2         CONTRACTOR'S DUTY FOR COMPLIANCE OF SERVICES WITH AGREEMENT
Contractor represents and warrants that it shall not perform any aspect of
the services that it knows or has reason to believe cannot be performed in
conformity with the provisions of this Agreement. If Contractor determines
that it cannot perform Services in conformity with these provisions,
Contractor shall immediately advise Exxon and work with Exxon to develop a
mutually satisfactory resolution for the inability to perform.

                            ARTICLE 8. RETURNED GOODS

Should Exxon elect to return to Contractor, and an authorized Contractor
employee has agreed to receive prior to being returned, on specification or
carrier damaged Products processed and delivered by Contractor, Exxon shall
be responsible for all transportation costs and Contractor's charges. In the
event off specification Product, which is confirmed by Contractor's retained
sample or non-salable Product as specified in Exhibit 1, which is noted an
Contractor's bill of lading and co-signed by both carrier and Contractor
authorized employee at time of delivery (for example, Product contamination
attributed to Contractor) was processed and delivered by Contractor, it shall
be returned at Contractor's cost including reimbursement to Exxon for all
transportation, insurance, Product, Service or material charges.

                 ARTICLE 9: HEALTH, SAFETY AND RELATED POLICIES

9.1         CONTRACTOR'S HEALTH AND SAFETY OBLIGATIONS

Contractor shall be responsible for providing a healthy and safe work place
and working environment for its employees and Subcontractors during
performance of Services. Contractor shall protect the health and safety of
Contractor's, Subcontractors' and Exxon's employees, the public, and other
third parties from any danger associated with the Services. All tools,
equipment, facilities and other items used by the Contractor and its
practices employed to accomplish the Services are considered part of the
working environment. As minimum health and safety requirements, Contractor
acknowledges and agrees that it is responsible for and shall ensure that all
Services are performed in compliance with any and all:
       (a)    Application Law;
       (b)    Health and safety requirements of Exxon set out in Exhibit G; and

In addition, Contractor agrees that it is responsible and shall ensure that
all Services are performed in compliance with any changes to Exhibit G made
by Exxon in accordance with Section 9.2 below. Contractor agrees to adopt
whatever methods, procedure and precautions are necessary to comply with the
provisions in this Article 9.

9.2         CHANGES IN HEALTH AND SAFETY REQUIREMENTS
Exxon may modify or replace at any time the provisions of Exhibit G regarding
any health or safety rule(s), regulation(s) or policy(s) applicable to
Services under this Agreement by notifying Contractor either orally or in
writing without complying with any provision on giving notice in this
Agreement.

9.3         RIGHTS AND REMEDIES

Contractor acknowledges that compliance with the provisions of this Article 9
are of the highest importance. Any breach of this Article 9 or the provisions
of Exhibit G or H as may be modified shall constitute a substantial and
material breach of the Agreement entitling Exxon to exercise the rights and
remedies specified in this Agreement and any other rights and remedies under
applicable Law or equity.

                            ARTICLE 10: ENVIRONMENTAL

In the event of any Product spills or other environmentally polluting
discharges arising from the operations of the Contractor's facility, clean up
and/or resulting liability for such spills or discharges shall be the sole
responsibility of Contractor. In the event of any Product spills or other
environmentally polluting discharges arising from the operation of delivering
or receiving vessel or vehicle operated by Exxon or its contractors or any
other entity except Contractor acting on behalf of or at the direction of
Exxon, Contractor is authorized to commence containment or clean up
operations as deemed appropriate or necessary and Contractor shall notify
Exxon immediately of such operations. All reasonable costs for containment or
cleanup for such spill or discharge shall be borne by Exxon. In the event a
spill or discharge is the result of joint negligence by both Contractor and
Exxon, costs of containment or clean up shall be borne jointly by Contractor
and Exxon In proportion to each party's negligence. Nothing herein shall
prevent either Exxon or Contractor from recovering any costs resulting from
the negligent act or omission of such contractor or its agents. With regard
to providing Services described herein, ASSI shall be deemed "Contractor" for
purposes of all environmental laws and regulations.


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<PAGE>

                                         Continuing Services Agreement PIA032398

ASSI shall be considered "generator" of all wastes generated on or from the
Premises in or from storage tanks or containment areas for purposes of
federal, state or local hazardous and non-hazardous waste laws and
regulations. ASSI shall perform the duties and responsibilities of the
"generator" in compliance with all applicable laws and regulations, including
(without limitation) identifying, packaging, manifesting, reporting, record
keeping, handling, transportation and disposing of all hazardous liquid or
solid waste removed from the facility. For the purpose of this agreement,
waste shall include but not be limited to, line flush, leakage and expired
Quality Control Samples. Any waste not specifically identified as the
responsibility of Exxon shall be the responsibility of Contractor. Exxon
agrees to notify Contractor immediately if any component supplied by Exxon is
or becomes classified as toxic or hazardous, and Exxon will remove inventory
of any such component from Contractor's premises at the end of the contract
or if use of such component is discontinued.

Material Safety Data Sheets: Exxon shall furnish to Contractor Material
Safety Data Sheets, including warnings and safety and health information
concerning the products and/or the containers for such products sold
hereunder. Contractor agrees to communicate such information to all persons
Contractor can reasonably foresee may be exposed to or may handle such
materials or containers, including but not limited to Contractor's employees,
agents, contractors or customers. Exxon Material Safety Data Sheets are
available on a 24 hour fax-it-back basis by calling 1-800-298-4007 and
entering the Exxon Product code for each Product as set out in Appendix F
attached hereto.

                              ARTICLE 11: INSURANCE

11.1        MINIMUM INSURANCE REQUIREMENTS
Contractor shall carry and maintain in force the following insurances in
amounts and with companies satisfactory to Exxon:

       (a)    WORKERS' COMPENSATION AND EMPLOYERS' LIABILITY
              For all its employees engaged in performing Services, workers'
              compensation and employers' liability insurance or similar social
              insurance in accordance with Law which may be applicable to those
              employees.

       (b)    COMPREHENSIVE GENERAL LIABILITY
              Its normal and customary comprehensive general liability insurance
              coverage and policy limits or at least $1,000,000.00, whichever is
              greater, providing coverage for injury, death or property damage
              resulting from each occurrence.

Contractor further agrees that the minimum insurance requirements as set forth
above shall not limit or waive Contractor's legal or contractual
responsibilities to Exxon or to others.

11.2        PROOF OF INSURANCE AND CHANGES
Upon request by Exxon, Contractor shall have its insurance carrier(s) furnish to
Exxon certified copies of the required insurance policies and/or certificates of
insurance specifying that no insurance shall be canceled or materially changed
while Services are in progress without thirty (30) calendar days prior written
notice to the requester.

11.3        SUBCONTRACTORS' INSURANCE
If Contractor subcontracts any part of the Services, Contractor shall require
its Subcontractors to maintain insurance specified in the subcontracts, but
shall not require Subcontractors to carry insurance that would duplicate the
coverage of the insurance carried by Contractor. Upon request by Exxon,
Contractor shall have its Subcontractors furnish the same evidence of
insurance required by Contractor.

11.4        COMMENCEMENT OF SERVICES
Contractor and its Subcontractors shall not begin Services until all of the
insurance required of Contractor and its Subcontractors is in force and the
necessary documents, if requested by Exxon, have been received.

                           ARTICLE 12: APPLICABLE LAW

The validity, interpretation and construction of this Agreement shall be
governed by the Laws of the State of Texas without reference to that state's
principles of conflicts of law.

                      ARTICLE 13: FEDERAL CONTRACT CLAUSES

Exxon is an U.S. Government contractor. This Agreement therefore incorporates by
this reference, and each party shall comply with, all applicable federal laws,
regulations and orders, including without limitation those relating to equal
opportunity, utilization of small business concerns and small disadvantaged
business concerns, employment of the


                                       4
<PAGE>

                                         Continuing Services Agreement PIA032398

handicapped, employment of disabled veterans and veterans of the Vietnam era,
and the environment. Contractor certifies that no facility which has been the
subject of a conviction under the applicable portion of the Clean Air Act (42
U.S.C. 7413(c)(1)) or Clean Water Act (33 U.S.C. 1319(c)) and is listed by the
Environmental Protection Agency as a violating facility will he used in the
performance of any Services incorporating this Agreement. Those Federal Contract
Clauses which are required to be expressly incorporated into this Agreement are
contained in the attached Federal Contract Supplement (Exhibit F), and the
parties agree to the terms and conditions contained in that Supplement.

                               ARTICLE 14: NOTICES

14.1        AGREEMENT NOTICES
Notices intended to affect this Agreement and required or permitted to be given
under this Agreement to Exxon or Contractor, shall be in writing and deemed to
be properly given if addressed to the appropriate party at the address below,
and:

       (a)    Delivered in person,
       (b)    Sent by facsimile with confirmation,
       (c)    Deposited in the United States mail with first class postage
              prepaid, or
       (d)    Delivered by private, prepaid courier


EXXON                                  CONTRACTOR
-------                                ----------
Exxon Company, U.S.A.                  Mr. Robert R. Zimmerman
800 Bell Street, Room 2405D            Asphalt Supply and Services, Incorporated
Houston, Texas 77002                   509 West Railroad Street
Attn: CONTRACT FACILITY COORDINATOR    Laurel, Montana 59044
Phone: 713/656-2411                    Phone: (406) 628-2277/4353
Fax 713/656-7319                       Fax: (406) 628-6459

14.2        ADDRESS CHANGES
Any address for notices under Sections 14.1 above may be changed by written
notice to the other party as provided in this Article 14.

                            ARTICLE 15: SURVIVORSHIP

The provisions of Articles 3, 7, 15 and 16 of this Principal Document and
ArticIes 3, 4, 7, 8 and 9 of the General Terms and Conditions shall survive any
expiration or termination of this Agreement.

                        ARTICLE 16: AGREEMENT ASSIGNMENTS

Contractor shall not assign this Agreement in whole or in part (including any
sum accruing to Contractor) without the prior written approval of Exxon, which
approval may be withheld for any reason. Any assignment of this Agreement, if
approved by Exxon, shall not relieve Contractor of its responsibilities under
this Agreement.

                             ARTICLE 17: AMENDMENTS

Any alteration deletion or addition to any of the terms of this Agreement shall
only be effective if made in a written amendment to this Agreement, duly
executed by Exxon and Contractor. Once an Agreement is made, it shall be deemed
incorporated as of its effective date for all ongoing and future Services,
unless expressly stated to the contrary in the amendment.

                             ARTICLE 18: PRECEDENCE

In the event of a conflict between any provisions of this Agreement, the
terms in this Principal Document shall take precedence and govern over the
General Terms and Conditions and the Exhibits, and the General Terms and
Conditions shall take precedence and govern over the Exhibits.

                          ARTICLE 19: ENTIRE AGREEMENT

This Agreement constitutes the entire agreement between Contractor and Exxon,
and it supersedes all prior negotiations, representations, or agreements, either
oral or written, related to this Agreement.


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                                         Continuing Services Agreement PIA032398

                         ARTICLE 20: CONDITION PRECEDENT

If Contractor is the first party to execute this Agreement below, Exxon's
acceptance of this Agreement is conditioned on Exxon's review and execution of
this Agreement.

         IN WITNESS WHEREOF, the parties have duly executed this Agreement in
duplicate originals.

                                              Exxon Company, U.S.A.
         (Contractor)                         (a division of Exxon Corporation)

By: Asphalt Supply & Service Inc.             By: /s/ W R Carter
   ------------------------------------          -------------------------------

Name  [ILLEGIBLE]                             Name    W R Carter
     ----------------------------------            -----------------------------
     (Typed or Printed)                            (Typed or Printed)

Title  President                              Title  [ILLEGIBLE] Operations Mgr.
      ---------------------------------            -----------------------------
Date    4-3-98                                Date  4/6/99
    -----------------------------------           ------------------------------


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