Exhibit 4.6

Exhibit 4.6

     THESE SECURITIES HAVE NOT BEEN REGISTERED WITH THE UNITED STATES SECURITIES
AND EXCHANGE COMMISSION OR THE SECURITIES COMMISSION OF ANY STATE. THE
SECURITIES MAY NOT BE RESOLD OR TRANSFERRED EXCEPT AS PERMITTED UNDER THE
SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"), PURSUANT TO REGISTRATION OR AN
EXEMPTION THEREFROM.

No. ___1___                                                 US$1,000,000


                              EARTH SCIENCES, INC.
                              AMENDED AND RESTATED
                 10% CONVERTIBLE DEBENTURE DUE SEPTEMBER 8, 2003

     THIS DEBENTURE is one of a duly authorized issue of Debentures of Earth
Sciences, Inc., a corporation duly organized and existing under the laws of the
State of Colorado (the "Company"), designated as its 10% Convertible Debenture
Due September 8, 2003, in an aggregate principal amount not exceeding US$
1,000,000 (herein, the "Debentures"). This Debenture is issued as a replacement
of and contains modifications to the Company's previous debenture due on March
31, 2000 (as amended) in the principal amount of $1,000,000 issued to the Holder
(the "Prior Debenture"). The Holder's acceptance of this Debenture and
concurrent relinquishment and cancellation of the Prior Debenture is expressly
conditioned upon the Company's payment of all outstanding attorneys' fees,
accrued and unpaid interest, and other charges owing on the Prior Debenture as
of the date of this Debenture.

     FOR VALUE RECEIVED, the Company promises to pay to Tectonic Construction
Co., the registered holder hereof (the "Holder"), the principal sum of US$
1,000,000.00, on September 8, 2003 (the "Maturity Date") together with interest
on the principal sum outstanding from time to time at the annual rate equal to
the greater of (i) the prime rate as reported by Bank One, Denver, Colorado
("Prime Rate") plus two percent (2%), or (ii) ten percent (10%), adjusted
quarterly and computed on the basis of the actual number of days elapsed in a
365-day year. All accrued interest shall be payable in arrears, and shall be due
and payable at the end of each calendar quarter or, if earlier, on the
Conversion Date (as hereinafter defined). Accrual of interest shall commence on
the date hereof and shall continue until payment in full of the principal sum
has been made or duly provided for. All accrued and unpaid interest so payable,
together with any and all other amounts payable hereunder, less any amounts
required by law to be deducted or withheld, will be paid on the Maturity Date
or, if earlier, on the Conversion Date, and shall be paid to the person in whose
name this Debenture (or one or more predecessor Debentures) is registered on the
records of the Company regarding registration and transfers of the Debentures
(the "Debenture Register") on the Conversion Date or tenth day prior to the
Maturity Date, as the case may be; provided, however, that the Company's
obligation to a transferee of this Debenture arises only if such transferee
executes a subscription agreement and investment agreement as the Company may
reasonably require. The principal of, and interest on, this Debenture are
payable in such coin or currency of the United States of America as at the time
of payment is legal tender for payment of public and private debts, at the
address last appearing on the Debenture Register of the Company as designated in
writing by the Holder from time to time. The Company may prepay a portion or all
of the Debentures at any time. The Company shall provide the Holder with no less
than 30 days written notice of any prepayment. The forwarding of the Company's
check shall, subject to collection, constitute a payment of interest and
principal hereunder and shall satisfy and discharge the liability for principal
and interest on this Debenture to the extent of the sum represented by such
check. Any payments received by Holder will be applied in the following order:
(i) any collection and other costs, including, without limitation, attorneys'
fees, which the Holder may have incurred in procuring the Company's performance
hereunder, (ii) any charges assessed by the Holder, (iii) payment of the
interest then accrued and due on the unpaid interest and unpaid principal
balance of this Debenture, and (iv) principal.

     The Holder may, in its sole discretion, with at least ninety (90) days'
advance written notice to the Company, demand payment of principal, which
payment shall be applied in the same order described above. The combined total

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amount of quarterly principal which the Holder may demand pursuant to this
Debenture and pursuant to the $250,000 Promissory Note of even date herewith
issued by the Company to the Holder (the "Note") shall not exceed $100,000 in
any quarter. The first quarterly payment of principal shall not be due earlier
than January 1, 2001, provided that the Holder demands same in writing by no
later than October 1, 2000.

     This Debenture is subject to the following additional provisions:

     1. This Debenture is exchangeable for an equal aggregate principal amount
of Debentures of different authorized denominations, as requested by the Holders
surrendering the same. No service charge will be made for such registration or
transfer or exchange.

     2. This Debenture has been issued subject to investment representations of
the original purchaser hereof and may be transferred or exchanged only in
compliance with the Securities Act of 1933, as amended (the "Act") and the terms
of the Subscription Agreement. Prior to due presentment for transfer of this
Debenture, the Company and any agent of the Company may treat the person in
whose name this Debenture is duly registered on the Debenture Register as the
owner hereof for the purpose of receiving payment as herein provided and for all
other purposes, whether or not this Debenture be overdue, and neither the
Company nor any such agent shall be affected by notice to the contrary.

     3. The Holder of this Debenture shall be entitled, at any time during the
period commencing on and after September 8, 2000 and expiring on the Maturity
Date, to convert up to the entire outstanding principal amount on this
Debentures into shares of common stock, par value $.0l per share (the "Common
Stock"), of the Company at a conversion price for each share of the Common Stock
of the lesser of $.21 or the average trading price per share of Common Stock on
the Conversion Date. Nevertheless, the aggregate combined number of shares of
Common Stock into which this Debenture and the Note may be converted shall not
exceed 1,000,000. Such conversion shall be effectuated by surrendering the
Debenture to the Company with the form of conversion notice attached hereto as
Exhibit A, executed by the Holder evidencing its intent to convert the
Debenture. The amount of accrued but unpaid interest as of the Conversion Date
shall not be subject to conversion but shall be paid in cash as of the
Conversion Date. No fraction of shares of the Common Stock or scrip representing
fractions of shares will be issued on conversion, but the number of shares of
the Common Stock issuable shall be rounded to the nearest whole share. The date
on which notice of conversion is given shall be deemed to be the date on which
the Holder has delivered this Debenture, with the conversion notice duly
executed, to the Company, or if earlier, the date set forth in such notice of
conversion if the Debenture is received by the Company within three business
days thereafter. Such date is referred to herein as the "Conversion Date."
Facsimile delivery of the conversion notice shall be accepted by the Company.
Certificates representing Common Stock upon conversion will be delivered to the
Holder within five (5) business days from the date the notice of conversion is
delivered to the Company. The Common Stock issuable upon conversion will not
have been registered under the Securities Act of 1933, and will be issued in
reliance upon exemptions from the registration requirements of the Securities
Acts of 1933, and the transfer of such Common Stock will be subject to
restrictions imposed by applicable securities laws. A legend restricting the
transfer of the Commons Stock may be placed on any Certificate representing the
Common Stock. If the Holder converts less than then entire outstanding principal
amount of this Debenture, the Company shall execute and issue to the Holder a
substitute debenture for the remaining unpaid and unconverted principal amount,
and shall deliver same to the Holder together with the stock certificate(s).

     4. Any of the following shall constitute an "Event of Default":

          a. The Company defaults in the payment of principal or interest on
          this Debenture as and when the same is due and payable and such
          default continues for five (5) business days after the receipt of
          written notice that the Company is in default hereunder; or

          b. Any of the representations or warranties made by the Company
          herein, in the Subscription Agreement, or in any certificate or
          financial or other written statements heretofore or hereafter
          furnished by or on behalf of the Company in connection with the
          execution and delivery of this Debenture or the Subscription Agreement
          is false or misleading in any material respect at the time made; or

<PAGE>


          c. The Company fails to perform or observe, in any material respect,
          any other covenant, term, provision, condition, agreement or
          obligation of the Company under this Debenture, or under the
          Subscription Agreement, or under any related agreement, or under any
          document or instrument granting security for amounts owing under this
          Debenture including, without limitation, any of the following
          documents: Subscription Agreement and Investment Agreement of Earth
          Sciences, Inc.; Subordination Agreement among Tectonic Construction
          Co., Yankee Atomic Electric Company, Vermont Yankee Nuclear Power
          Corporation, and ESI Resources Limited dated June 12, 1997, Guarantee
          Agreement dated June 12, 1997 by Earth Sciences Extraction Company
          ("ES Extraction") in favor of Tectonic Construction Co.; and Guarantee
          Agreement dated June 12, 1997 by ESI Resources Limited, in favor of
          Tectonic Construction Co. (collectively referred to herein as the
          "Loan Documents"), and such failure continues uncured for a period of
          five (5) business days after the receipt of written notice that the
          Company is in default hereunder (it being understood that in the case
          of defaults which can not reasonably be cured within a 5-day period no
          grace period shall be necessary as a precondition to the failure to
          perform such covenant constituting an Event of Default); or

          d. The Company (1) makes an assignment for the benefit of creditors or
          commence proceedings for its dissolution; or (2) applies for or
          consents to the appointment of a trustee, liquidator or receiver for
          its or for a substantial part of its property or business; or

          e. A trustee, liquidator or receiver is appointed for the Company or
          for a substantial part of its property or business without its
          consent, and is not discharged within sixty (60) days after such
          appointment; or

          f. Bankruptcy, reorganization, insolvency or liquidation proceedings
          or other proceedings for relief under any bankruptcy law or any law
          for the relief of debtors is instituted by or against the Company and,
          if instituted against the Company, is not dismissed within sixty (60)
          days after such institution or the Company by any action or answer
          approves of, consents to, or acquiesces in any such proceeding or
          admits the material allegations of, or defaults in answering a
          petition filed in any such proceeding; or

          g. The Company fails to make any required material payments, fees,
          taxes, costs, insurance premiums when due beyond any applicable grace
          period; or

          h. The Company defaults on the payment of any material indebtedness,
          except for the Company's current indebtedness to the Bank of Hong
          Kong, for borrowed money beyond any applicable grace period; or

          i. Any judgment, levy or attachment is rendered against the Company or
          any of its assets or properties in an amount in excess of $50,000 and
          such judgment, levy or attachment is not dismissed, stayed, bonded or
          discharge within thirty (30) days of the date of entry thereof, or

          j. The control of the Company, ESI Resources Limited, ES Extraction,
          ADA-ES, Inc. or ADA -Environmental Solutions, LLC ("ADA ES"), is
          changed by reason of merger or acquisition of shares of either
          company, or sale of substantially all assets of either company; or

          k. The Company allows any of the following conditions without the
          prior written waiver of the Holder:

             i. the declaration of a dividend to holders of the Common Stock;
             ii. the declaration of a distribution to the Company by ADA ES or
             ADA-ES, Inc.;
             iii. capital expenditures in any calendar quarter exceeding
             $100,000; or
             iv. diminution by more than $100,000 of consolidated working
             capital at any calendar quarter end date, irrespective of this or
             any other convertible debenture, of less than the current
             consolidated working capital of the Company as of June 30, 2000,
             which was a deficit of $766,000.

<PAGE>


Upon the occurrence of any Event of Default or at any time thereafter, and in
each and every such case, unless such Event of Default has been waived in
writing by the Holder (which waiver shall not be deemed to be a waiver of any
subsequent Event of Default) at the option of the Holder and in the Holder's
sole discretion, then or at any time thereafter, the whole of said principal sum
then remaining unpaid hereunder, together with all interest accrued thereon, and
all other sums owing hereunder or under the Loan Documents, shall immediately
become due and payable upon the Company's receipt of the Holder's written notice
of acceleration ("Acceleration") and the liens given to secure the payment of
this Debenture may be foreclosed and the Holder may pursue all rights and
remedies available under this Debenture, or under the Loan Documents, or
otherwise available at law or in equity. If an Event of Default occurs due to
non-payment of this Debenture or the Note and the Holder does not deliver to the
Company a written notice of default and Acceleration, then the Maturity Date
shall automatically and without notice to the Holder be changed to the next
September 8 following the date of the Company's first missed payment hereunder.

     6. Following the occurrence of an Event of Default due to non-payment of
this Debenture or the Note, and so long as any such Event of Default remains
outstanding and uncured, if the Holder does not declare this Debenture in
default and provide the Company with a written notice of Acceleration, without
notice to the Company all unpaid principal and all other interest and charges
payable hereunder shall accrue interest at the annual rate equal to the greater
of (i) Prime Rate plus five percent (5%), or (ii) fifteen percent (15%).
Following the occurrence of an Event of Default, and for so long as any such
Event of Default shall remain outstanding and uncured, and upon the Holder's
written notice of such Event of Default and Acceleration, the Company promises
to pay interest on the outstanding principal balance of this Debenture, and on
any and all other amounts then outstanding, at an annual rate of interest equal
to the greater of (i) Prime Rate plus five percent (5%), or (ii) eighteen
percent (18%) per annum, provided that any interest which has accrued at the
default rate shall be paid at the time of, and as a condition precedent to the
curing of any default under any statutory right to cure. The fluctuating default
rates at which interest accrues shall be adjusted simultaneously, at each
announced change of the Prime Rate. Failure to exercise such option or charge of
such increased interest shall not be a waiver of the right to do so at any
future time or with respect to any other default.

     7. No provision of this Debenture shall alter or impair the obligation of
the Company which is absolute and unconditional, to pay the principal of, and
interest on, this Debenture at the time, place, and rate, and in the coin or
currency, herein prescribed. This Debenture and all other Debentures now or
hereafter issued of similar terms are direct obligations of the Company. The
Company shall pay all costs and expenses, including reasonable attorneys' fees,
which the Holder may incur in connection with any effort or action to collect
amounts due under this Debenture.

     8. No recourse shall be had for the payment of the principal of, or the
interest on, this Debenture, or for any claim based hereon, or otherwise in
respect hereof, against any incorporator, shareholder, officer or director, as
such, past, present or future, of the Company or any successor corporation,
whether by virtue of any constitution, statute or rule of law, or by the
enforcement of any assessment or penalty or otherwise, all such liability being,
by the acceptance hereof and as part of the consideration for the issue hereof,
expressly waived and released.

     9. The rights or remedies of the Holder as provided in this Debenture and
the Loan Documents shall be cumulative and concurrent and may be pursued singly,
successively, or together against the Company, the property described in the
Loan Documents, and any other funds, property or security held by the Holder for
the payment hereof or otherwise at the sole discretion of the Holder. The
failure to exercise any such right or remedy shall in no event be considered as
a waiver or release of such rights or remedies or the right to exercise them at
any later time.

     10. In the event the interest provisions hereof or any exactions provided
for herein, or in the Loan Documents or any other instrument securing this
Debenture shall result, because of any reduction of principal, or for any reason
at any time during the life of this loan, in any effective rate of interest
which, for any month, transcends the limit of the usury or any other law
applicable to the obligation evidenced hereby, all sums in excess of those
lawfully collectible as interest for the period in question shall, without
further agreement or notice between or by any party hereto, be applied upon
principal immediately upon receipt of such moneys by Holder, with the same force
and effect as though the payor had specifically designated such extra sums to be
so applied to principal and Holder had agreed to accept such extra payment as a

<PAGE>


premium-free prepayment. In no event shall any agreed to or actual exaction as
consideration for this obligation transcend the limits imposed or provided by
the laws applicable to this transaction or the Company hereof in the
jurisdiction in which any of the security herefor is located for the use or
detention of money or for forbearance in seeking its collection.

     11. The Company and all endorsers, guarantors and all persons liable or to
become liable on this Debenture waive presentment, protest and demand, notice of
protest, demand and dishonor and nonpayment of this Debenture, and consent to
any and all renewals and extensions in the time of payment hereof, and agree,
further, that at any time and from time to time without notice, the terms of
payment herein may be modified or the security described in the Loan Documents
released in whole or in part or increased, changed or exchanged by agreement
between the Holder hereof and any owner of the property affected by said Loan
Documents without in anywise affecting the liability of any party to this
instrument or any person liable or to become liable with respect to any
indebtedness evidenced hereby. The right to plead any and all statues of
limitation as a defense to any demand on this Debenture, or any guaranty hereof,
or any agreement to pay the same, or any demand secured by the Loan Documents,
or any and all obligations or liabilities arising out of or in connection with
this Debenture or in the Loan Documents, is expressly waived by each and every
of the Company, endorsers, or guarantors to the fullest extent permitted by law.

     12. Any forbearance of Holder in exercising any right or remedy hereunder
or under the Loan Documents, or otherwise, afforded by applicable law, shall not
be a waiver of or preclude the exercise of any right or remedy. The acceptance
by Holder of payment of any sum payable, hereunder after the due date of such
payment shall not be a waiver of Holder's right to either require prompt payment
when due of all other sums payable hereunder or to declare a default for failure
to make prompt payment. Holder shall at all times have the right to proceed
against any portion of the security held herefor in such order and in such
manner as Holder may deem fit, without waiving any rights with respect to any
other security. No delay or omission on the part of Holder in exercising any
right hereunder shall operate as a waiver of such right or of any other right
under this Debenture.

     13. This Debenture shall be governed by and construed in accordance with
the laws of the State of Colorado without regard to the choice of law provisions
thereof, and in the event this Debenture is placed in the hands of any attorney
for collection or is collected through any legal proceedings, the undersigned
promises to pay (in addition to costs and disbursements otherwise allowed), to
the extent permitted by law, reasonable attorneys' fee and legal costs (whether
or not suit is commenced and whether or not incurred in connection with appeal
of a lower court judgment or order or in collecting any judgment entered
therein),and if foreclosure is made by any public official, reasonable
attorneys' fees and legal costs shall be added by such public official to the
cost of foreclosure. The undersigned hereby represents that the proceeds of the
loan evidenced by this Debenture will be used for a commercial or business
purpose.

     14. Time is of the essence with regard to the performance of the
obligations of the Company in this Debenture and each and every term, covenant
and condition herein by or applicable to the Company.

     15. This Debenture is guaranteed by three separate guarantees executed by
ADA ES, ESI Resources Limited, and ES Extraction, each wholly owned subsidiaries
or affiliates of the Company and each of which guaranties are secured by
corresponding security agreements (the "Security Agreements").

     16. The Company hereby irrevocably waives, to the fullest extent permitted
by law, any and all right to trial by jury in any legal proceeding arising out
of or relating to this Debenture and the other Loan Documents or the
transactions contemplated thereby. In any action which may be brought under this
Debenture, Holder hereby irrevocably consents to the personal jurisdiction of
any State District Court or Federal Court located in the State of Colorado, and
further stipulates and agrees that venue shall be proper in the State of
Colorado for any such actions and further agrees not to seek a change of venue
to any court outside the State of Colorado without the consent of Holder.

     17. All notices required or permitted to be given pursuant to the terms
hereof shall be in writing and shall be delivered either by (a) certified mail,
return receipt requested, in which case notice shall be deemed received three
(3) business days after deposit, postage prepaid in the U.S. mail, (b) a
reputable messenger service or a nationally-recognized overnight courier, in

<PAGE>


which case notice shall be deemed received one (1) business day after deposit
with such messenger or courier, (c) facsimile or other telecopy transmission
(followed with "hard copy" sent by a nationally-recognized overnight courier or
mail as aforesaid), in which case notice shall be deemed received when the
facsimile or other telecopy transmission is received, provided such receipt
occurs before 5:00 p.m. recipient's local time on a business day, otherwise at
8:30 a.m. recipient's local time on the next business day or (d) personal
delivery with receipt acknowledged in writing, in which case notice shall be
deemed received upon delivery. Notices shall be deemed given or sent upon
deposit in the U.S. mail in the case of clause (a) above, or upon deposit with a
reputable messenger or courier in the case of clause (b) above. Notices shall be
deemed given or sent upon receipt of electronic confirmation in the case of
clause (c) above or upon receipt in the case of clause (d). All such notices
shall be addressed as follows:

                           To Maker:

                           Earth Sciences, Inc.
                           Attn:  Mark McKinnies
                           8100 Southpark Way #B-2
                           Littleton, CO  80120
                           Fax:  303-734-0330

                           To Holder:

                           Tectonic Construction Co.
                           100 Cherry
                           Denver, CO  80220
                           Fax:  303-394-9822

                           With a Copy To:

                           Gorsuch Kirgis LLP
                           Attn:  Stephen A. Weinstein, Esq.
                           Tower I, Suite 1000
                           1515 Arapahoe Street
                           Denver, CO  80202
                           Fax:  303-376-5001


     IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed by an officer thereunto duly authorized. EARTH SCIENCES, INC.



                                            By: /s/ Mark H. McKinnies
                                            -------------------------------
                                            Name: Mark H. McKinnies
                                            Title: President


<PAGE>


                                    EXHIBIT A

                              NOTICE OF CONVERSION

                    (To be Executed by the Registered Holder
                       in order to Convert the Debenture)


     The undersigned hereby irrevocably elects to convert the above Debenture
No. ______ into shares of Common Stock of EARTH SCIENCES, INC. (the "Company")
according to the conditions hereof, as of the date written below.



                                            ---------------------------------
                                            Date of Conversion



                                            ---------------------------------
                                            Applicable Conversion Price



                                            [SUBSCRIBER]



                                            ----------------------------------
                                            Signature



                                            Address:


                                            ----------------------------------

                                            ----------------------------------


* The original Debenture and Notice of Conversion must be received by the
Company by the third business day following the Date of Conversion.