<PAGE>   1

                                                                   EXHIBIT 10.22

                                                                  EXECUTION COPY



         FIRST AMENDMENT, WAIVER AND CONSENT dated as of December 29, 1995
("Amendment") to LOAN AND SECURITY AGREEMENT dated as of October 18, 1995 (the
"Loan Agreement") among SMITH ENVIRONMENTAL TECHNOLOGIES CORPORATION, BCM
ENGINEERS INC., a Pennsylvania corporation, BCM ENGINEERS INC., an Alabama
corporation, RIEDEL ENVIRONMENTAL SERVICES INC., each of the Lenders which are
or which may become parties to the Loan Agreement and CHEMICAL BANK, as Agent
for the Lenders.  Terms which are capitalized herein and not otherwise defined
shall have the meanings ascribed to them in the Loan Agreement.

         WHEREAS,  pursuant to paragraph 14(l) of the Loan Agreement, Smith
Environmental may not pay dividends on its Junior Securities, including the
outstanding shares of non-voting preferred stock of Smith Environmental held by
the ESOP (the "ESOP Stock"), unless all of the conditions precedent to any such
payment, as set forth in sub-clause (I) following the proviso to clause (ii) of
such paragraph 14(l), shall have occurred (such conditions, the "Compliance
Conditions"); and

         WHEREAS, Smith Environmental has advised the Agent, pursuant to a
letter dated December 28, 1995, a copy of which is annexed hereto, that (i)
Smith Environmental proposes to make dividend payments in cash to the ESOP, as
holder of the ESOP Stock (the "ESOP Dividend") for the fiscal quarter ending
December 31, 1995, notwithstanding the fact that the Compliance Conditions
shall not have occurred at the time of such proposed payment, (ii) the
Borrowers will be unable to install a management information system by January
1, 1996, as required under paragraph 14(a) of the Loan Agreement and (iii)
Smith Environmental and its Subsidiaries will be unable to maintain a
consolidated Tangible Net Worth of at least the minimum levels required under
paragraph 14(o)(ii) of the Loan Agreement for the measuring periods described
therein; and

         WHEREAS, the Account Owners have failed to deliver to the Agent a
"flash" report for the month of November, 1995, as required under paragraph
11(b)(iii) of the Loan Agreement and the Borrowers have failed to deliver to
the Agent the internally prepared consolidated and consolidating balance sheet
of Smith Environmental and its Subsidiaries for the month of October, 1995 (the
"October Balance Sheet"), as required under Paragraph 14(b)(i) of the Loan
Agreement; and

         WHEREAS, Smith Environmental has requested that the Agent and the
Lenders (i) waive  as a Default the Account Owners' failure to deliver such
"flash" report, (ii) waive as an Event of Default the Borrowers' failure to
deliver the October Balance Sheet, (iii) waive the fulfillment of the
Compliance Conditions as a condition precedent to the payment of the ESOP
Dividend and (iv) amend the Loan Agreement so as to (A) modify the date upon
which such management information system must be installed and (B) revise the
minimum levels of Tangible
<PAGE>   2
Net Worth which must be maintained, and the Agent and each of the Lenders have
so agreed, upon the terms and subject to the conditions set forth in this
Amendment;

         NOW, THEREFORE, in consideration of the mutual promises contained
herein, and the payment of the fee described in Section 5(g) hereof, and for
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the Borrowers, the Lenders and the Agent hereby agree as
follows:

         1.      Waiver of Failure to Deliver Flash Report and October Balance
Sheet.  Upon the fulfillment of the conditions set forth in Section 5 hereof,
effective as of the date hereof, each of the Lenders and the Agent waive as a
Default the Account Owners' failure to deliver to the Agent by December 15,
1995 a "flash" report for the month of November, 1995, provided such "flash"
report is in fact delivered to the Agent within five (5) Business Days of the
date of this Amendment, and each of the Lenders and the Agent waive as an Event
of Default the Borrowers' failure to deliver the October Balance Sheet to the
Agent by November 30, 1995, provided the October Balance Sheet is in fact
delivered to the Agent within ten (10) Business Days of the date of this
Amendment.

         2.      Waiver of Compliance Conditions; Consent.  Upon the
fulfillment of the conditions set forth in Section 5 hereof, effective as of
the date hereof, each of the Lenders and the Agent waive as a condition
precedent to the  payment of the ESOP Dividend Smith Environmental's
fulfillment of the Compliance Conditions and each of the Lenders and the Agent
consent to the payment in cash to the ESOP of the ESOP Dividend for the fiscal
quarter ending December 31, 1995, provided (a) such payment occurs no later
than January 3, 1996, (b) such payment does not exceed an aggregate amount
greater than $97,500 and (c) the combined Excess Availability of the Borrowers,
after giving effect to such payment, when averaged under the combined average
Excess Availability of the Borrowers for the preceding period of twenty-nine
(29) consecutive days, is not less than $1,100,000.

         3.      Amendment.  Upon the fulfillment of the conditions set forth
in Section 5 hereof, effective as of the date hereof, the Loan Agreement is
hereby amended as follows:

                 (a)      Paragraph 14(a) of the Loan Agreement is amended by
deleting the date "January 1, 1996" and by substituting therefor the date
"March 31, 1996".

                 (b)      Paragraph 14(o) of the Loan Agreement is amended by
deleting subparagraph (ii) thereof in its entirety and by substituting the
following in lieu thereof:

                 "(ii) Consolidated Tangible Net Worth.  Smith Environmental
                 and its Subsidiaries, on a consolidated basis, shall
                 maintain at all times during each period set forth
                 below, a Tangible Net Worth





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<PAGE>   3
                          of not less than the amount set forth below opposite
                          each such period:

<TABLE>
<CAPTION>
                                                                    Minimum Consolidated
                           Measuring Period                          Tangible Net Worth
                           ----------------                         --------------------
                          <S>                                             <C>
                          (A) from Closing Date through                   $ 5,350,000
                          December 30, 1995

                          (B) from December 31, 1995                      $ 5,800,000
                          through March 30, 1996

                          (C) from March 31, 1996                         $ 6,400,000
                          through June 29, 1996

                          (D) from June 30, 1996                          $ 8,400,000
                          through September 29, 1996

                          (E) from September 30, 1996                     $10,400,000
                          through September 29, 1997

                          (F) from September 30, 1997                     $15,900,000
                          through September 29, 1998

                          (G) from September 30, 1998                     $20,900,000
                          and all times thereafter
</TABLE>


                 4.       Representations and Warranties.  In order to induce
the Lenders and the Agent to enter into this Amendment, Smith Environmental and
each other Borrower makes the following representations and warranties in favor
of each of the Lenders and the Agent (which representations and warranties
shall survive the execution and delivery of this Amendment) as of the date
hereof:

                          (a)     Smith Environmental and each other Borrower
has the corporate power, authority and legal right to execute, deliver and
perform this Amendment, and the instruments, agreements, documents and
transactions contemplated hereby, and has taken all actions necessary to
authorize the execution, delivery and performance of this Amendment, and the
instruments, agreements, documents and transactions contemplated hereby;

                          (b)     No consent of any Person (including, without
limitation, shareholders or creditors of Smith Environmental, as the case may
be) other than the Lenders,





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and no consent, permit, approval or authorization of, exemption by, notice or
report to, or registration, filing or declaration with, any governmental
authority, is required in connection with the execution, delivery, performance,
validity or enforceability of this Amendment, and the instruments, agreements,
documents and transactions contemplated hereby;

                          (c)     This Amendment has been duly executed and
delivered on behalf of Smith Environmental and each other Borrower by its duly
authorized officer, and constitutes the legal, valid and binding obligation of
Smith Environmental and each such Borrower, enforceable in accordance with its
terms;

                          (d)     Neither Smith Environmental nor any other
Borrower is in default under any indenture, mortgage, deed of trust, agreement
or other instrument to which it is a party or by which it may be bound.
Neither the execution and delivery of this Amendment, nor the consummation of
the transactions herein contemplated, nor compliance with the provisions hereof
or thereof will (i) violate any law or regulation, (ii) result in or cause a
violation by Smith Environmental or by any other Borrower of any order or
decree of any court or government instrumentality, (iii) conflict with, or
result in the breach of, or constitute a default under, any indenture,
mortgage, deed of trust, agreement or other instrument to which Smith
Environmental or any other Borrower is a party or by which it may be bound,
(iv) result in the creation or imposition of any lien, charge, or encumbrance
upon any of the property of Smith Environmental or of any other Borrower,
except in favor of the Agent for the benefit of the Lenders, to secure the
Liabilities, or (v) violate any provision of the Articles or Certificate of
Incorporation, By-Laws or any capital stock provisions of Smith Environmental
or of any other Borrower;

                          (e)     No Default or Event of Default has occurred
and is continuing, except for such Default and Event of Default as have been
waived pursuant to this Amendment;

                          (f)     Since the date of the Agent's receipt of
Smith Environmental's consolidated and consolidating financial statements for
the period ended August 31, 1995, no change or event has occurred which has had
or is reasonably likely to have a Material Adverse Effect; and

                          (g)     The recitals contained in this Amendment are
true and correct in all respects.

                 5.       Conditions Precedent.  This Amendment shall not
become effective until all of the following conditions, the fulfillment of each
of which is a condition precedent to the effectiveness of this Amendment, shall
have occurred or shall have been waived in writing by the Agent and the
Lenders.





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                          (a)     The Agent and each of the Lenders shall have
received a fully executed counterpart or original of this Amendment, together
with all schedules and exhibits hereto appropriately completed to the extent
required.

                          (b)     Upon the effectiveness of this Amendment, all
representations and warranties set forth in the Loan Agreement (except for such
inducing representations and warranties that were only required to be true and
correct as of a prior date) shall be true and correct in all material respects
on and as of the effective date hereof, and no Default or Event of Default
shall have occurred and be continuing.

                          (c)     No event or development shall have occurred
since the date of delivery to the Lenders of the Borrowers' most recent
financial statements which event or development has had or is reasonably likely
to have a Material Adverse Effect.

                          (d)     The Agent shall have received a certificate
from Smith Environmental, executed by its Chief Executive Officer or other
authorized officer, as to the accuracy and completeness of the representations
and warranties contained in Section 4 hereof.

                          (e)     All corporate and legal proceedings and all
documents and instruments executed or delivered in connection with this
Amendment shall be satisfactory in form and substance satisfactory to the
Lenders and their counsel, and the Lenders and their counsel shall have
received all information and copies of all documents which the Lenders and
their counsel may have requested in connection herewith and the matters
contemplated hereunder, such documents, when requested by them, to be certified
by appropriate corporate authorities.

                          (f)     The Lenders shall have received such further
agreements, consents, instruments and documents as may be necessary or proper
in the reasonable opinion of the Lenders, the Agent and their counsel to carry
out the provisions and purposes of this Amendment.

                          (g)     Within fifteen (15) Business Days of the date
of this Amendment, the Agent shall have received financial projections of Smith
Environmental and its Subsidiaries, prepared by the chief financial officer of
Smith Environmental on a consolidated and consolidating basis, which financial
projections (i) shall be in substantially the same form as the financial
projections of Smith Environmental and its Subsidiaries previously delivered to
the Agent and the Lenders, dated October 12, 1995 (the "October Projections"),
(ii) shall cover the same fiscal periods and shall be prepared on the same
month-by-month, quarter-by-quarter, and year-by-year basis as the October
Projections and (iii) shall be based on the October Projections, as modified so
as to reflect, among other things, actual balance sheet adjustments made since
the Closing Date, actual earnings for the fiscal year most recently ended and
actual costs and expenses paid or incurred in connection with the closing of
the Loan Agreement and the transactions which have occurred thereunder.





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                 6.       General Provisions.

                 (a)      In consideration of the execution and delivery of
this Amendment by the Lenders, each of the Borrowers promises that the Agent
shall receive from Smith Environmental, on January 3, 1996, for the pro rata
benefit of the Lenders, a non-refundable fee, in cash, in the amount of
$25,000, which fee shall be paid by the Agent's debit of the loan account of
Smith Environmental, effective as of the opening of business on such date.

                 (b)      Except as herein expressly amended, the Loan
Agreement and all other agreements, documents, instruments and certificates
executed in connection therewith, are ratified and confirmed in all respects
and shall remain in full force and effect in accordance with their respective
terms.

                 (c)      All references in the Other Agreements to the Loan
Agreement shall mean the Loan Agreement as waived and amended as of the
effective date hereof, and as waived and amended hereby and as hereafter
amended, supplemented or modified from time to time.  From and after the date
hereof, all references in the Loan Agreement to "this Agreement," "hereof,"
"herein," or similar terms, shall mean and refer to the Loan Agreement as
waived and amended by this Amendment.

                 (d)      This Amendment may be executed by the parties hereto
individually or in combination, in one or more counterparts, each of which
shall be an original and all which shall constitute one and the same agreement.

                 (e)      This Amendment shall be governed and controlled by
the laws of the State of New York without reference to its choice of law
principles.


                            [signature page follows]





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                 IN WITNESS WHEREOF, each of the Borrowers, BCM-Alabama, the
Lenders and the Agent have caused this Amendment to be duly executed by their
respective officers thereunto duly authorized as of the day and year first
above written.


<TABLE>
<S>                                               <C>
SMITH ENVIRONMENTAL TECHNOLOGIES                  RIEDEL ENVIRONMENTAL SERVICES INC.
CORPORATION

By: /s/ J. POLING                                 By: /s/ J. POLING            
   --------------------------------                  --------------------------------
   V.P. TREASURER                                     EXECUTIVE V.P.

BCM ENGINEERS INC.,                               CHEMICAL BANK, as a Lender and as
a Pennsylvania corporation                         Agent

By: /s/ J. POLING                                 By: /s/ E. JOSEPH HESS       
   --------------------------------                  --------------------------------
   V.P.                                              V.P.

BCM ENGINEERS INC.,                               BOT FINANCIAL CORPORATION
an Alabama corporation

By: /s/ J. POLING                                 By: /s/ WILLIAM R. YORK, JR. 
   --------------------------------                  --------------------------------
   V.P.                                              SENIOR V.P.
</TABLE>





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