<PAGE>   1
                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                                   FORM 10-Q/A


 QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT
                                     OF 1934


                For the Quarterly Period Ended February 28, 1998


                          Commission File Number 1-8368


                      LAIDLAW ENVIRONMENTAL SERVICES, INC.
             -----------------------------------------------------  
             (Exact name of registrant as specified in its charter)


           Delaware                                  51-0228924
-------------------------------                   -------------------
(State or other jurisdiction of                   (I.R.S. Employer
 incorporation or organization)                   Identification No.)


1301 Gervais Street Columbia, Suite 300, South Carolina             29201
-------------------------------------------------------           ---------
(Address of principal executive offices)                          (Zip Code)

       (803) 933-4210 (Registrant's telephone number, including area code)

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

   (Former name, address and former fiscal year, if changed since last report)

         Indicate by check mark whether the registrant (1) has filed all reports
required to be filed by Sections 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that the
registrant was required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days.

                            Yes   X     No 
                                -----      -----

         The number of shares of the issuer's common stock outstanding as of
April 7, 1998 was 338,398,600.




<PAGE>   2






                      LAIDLAW ENVIRONMENTAL SERVICES, INC.


                                      INDEX


PART 1     FINANCIAL INFORMATION


Item 6   Exhibits and Reports on Form 8-K                    3


Signatures                                                   8














<PAGE>   3


PART II - OTHER INFORMATION


ITEM 6.  EXHIBITS AND REPORTS ON FORM 8-K.

(a) Exhibits

(3)(a) Restated Certificate of Incorporation of the Company dated May 13, 1997
and Amendment to Certificate of Incorporation dated May 15, 1997 filed as
Exhibit 3(a) to the Registrant's Form 10-Q for the Quarter ended May 31, 1997
and incorporated herein by reference.

(3)(a)(i) Certificate of Correction Filed to Correct a Certain Error in the
Restated and Amended Certificate of Incorporation of the Company dated October
15, 1997 filed as Exhibit (3)(a)(i) to the Registrant's Form 10-K for the Year
ended August 31, 1997, and incorporated herein by reference.

(3)(a)(ii) Certificate of Amendment of Restated Certificate of Incorporation of
the Company dated February 19, 1998.

(3)(b) Amended and Restated Bylaws of the Company filed as Exhibit 4(ii) to the
Registrant's Current Report on Form 8-K dated July 29, 1997 and incorporated
herein by reference.

(4)(a) Rights Agreement dated as of June 14, 1989 between the Company and First
Chicago Trust Company as successor to Registrar and Transfer Company, as Rights
Agent filed as Exhibit 4(e) to the Registrant's Current Report on Form 8-K filed
on June 13, 1995 and incorporated herein by reference.

(4)(b) Amendment No. 1 dated as of March 31, 1995 to the Rights Agreement
between the Company and First Chicago Trust Company as successor to Registrar
and Transfer Company, as Rights Agent filed as Exhibit 4(f) to the Registrant's
Current Report on Form 8-K on June 13, 1995 and incorporated herein by
reference.

(4)(c) Amendment No. 2 dated as of April 30, 1997 to the Rights Agreement
between the Company and First Chicago Trust Company as successor to Registrar
and Transfer Company, as Rights Agent, filed as Exhibit 4(c) to the Registrant's
Form 10-Q for the quarter ended November 30, 1997, and incorporated herein by
reference.

(4)(d) Credit Agreement among Laidlaw Chem-Waste, Inc., Laidlaw Environmental
Services (Canada) Ltd., Toronto Dominion (Texas) Inc., The Toronto-Dominion
Bank, TD Securities (USA) Inc., the Bank of Nova Scotia, NationsBank, N.A. and
The First National Bank of Chicago and NationsBank, N.A. as Syndication Agent
dated as of May 9, 1997, filed as Exhibit 4(c) to the Registrant's Form 10-Q for
the Quarter ended May 31, 1997, and incorporated herein by reference.

(4)(e) $350,000,000 5% Subordinated Convertible Pay-In-Kind Debenture due 2009
issued by Registrant on May 15, 1997 to Laidlaw Transportation, Inc. the form of
which was included as an appendix to the Registrant's Definitive Proxy Statement
on Form DEF 14A, filed on May 1, 1997 and incorporated herein by reference.


                                     Page 3
<PAGE>   4
(4)(f) Registration Rights Agreement dated May 15, 1997 between Registrant,
Laidlaw Transportation, Inc. and Laidlaw Inc. included as an appendix to the
Registrant's Definitive Proxy Statement on Form DEF 14A, the form of which was
filed on May 1, 1997 and incorporated herein by reference.

(4)(g) Indenture dated as of May 1, 1993 between the Industrial Development
Board of the Metropolitan Government of Nashville and Davidson County
(Tennessee) and NationsBank of Tennessee, N.A., filed as Exhibit 4(f) to the
Registrant's Form 10-Q for the Quarter ended May 31, 1997, and incorporated
herein by reference.

(4)(h) Indenture of Trust dated as of February 1, 1995 between Carbon County,
Utah and West One Bank, Utah, now known as U.S. Bank, as Trustee, filed as
Exhibit 4(g) to the Registrant's Form 10-Q for the Quarter ended May 31, 1997,
and incorporated herein by reference.

(4)(i) Indenture of Trust dated as of August, 1995 between Tooele County, Utah
and West One Bank, Utah, now known as U.S. Bank, as Trustee, filed as Exhibit
4(h) to the Registrant's form 10-Q for the Quarter ended May 31, 1997, and
incorporated herein by reference.

(4)(j) Indenture of Trust dated as of July 1, 1997 between Carbon County, Utah
and U.S. Bank, a national banking association, as Trustee, filed as Exhibit 4(i)
to the Registrant's Form 10-Q for the Quarter ended May 31, 1997, and
incorporated herein by reference.

(4)(k) Indenture of Trust dated as of July 1, 1997 between Tooele County, Utah
and U.S. Bank, a national banking association, as Trustee, filed as Exhibit 4(j)
to the Registrant's Form 10-Q for the Quarter ended May 31, 1997, and
incorporated herein by reference.

(4)(l) Indenture of Trust dated as of July 1, 1997 between California Pollution
Control Financing Authority and U.S. Bank, a national banking association, as
Trustee, filed as Exhibit 4(k) to the Registrant's Form 10-Q for the Quarter
ended May 31, 1997, and incorporated herein by reference.

(4)(m) Stock Purchase Agreement between Westinghouse Electric Corporation
(Seller) and Rollins Environmental Services, Inc. (Buyer) for National Electric,
Inc. dated March 7, 1995 filed as Exhibit 2 to the Registrant's Current Report
on Form 8-K filed on June 13, 1995 and incorporated herein by reference.

(4)(n) Second Amendment to Stock Purchase Agreement (as referenced in Exhibit
(4)(m) above, dated May 15, 1997 among Westinghouse Electric Corporation,
Rollins Environmental Services, Inc. and Laidlaw Inc., filed as Exhibit 4(m) to
the Registrant's Form 10-Q for the Quarter ended May 31, 1997, and incorporated
herein by reference.

(4)(o) Promissory Note dated May 15, 1997 for $60,000,000 from Laidlaw
Environmental Services, Inc. to Westinghouse Electric Corporation, filed as
Exhibit 4(n) to the Registrant's Form 10-Q for the Quarter ended May 31, 1997,
and incorporated herein by reference.

(4)(p) Guaranty Agreement dated May 15, 1997 by Laidlaw Inc. to Westinghouse
Electric Corporation guaranteeing Promissory Note dated May 15, 1997 (as
referenced in Exhibit (4)(o)) from Laidlaw Environmental Services, Inc. to
Westinghouse Electric Corporation, filed as Exhibit 4(o) to the Registrant's
Form 10-Q for the Quarter ended May 31, 1997, and incorporated herein by
reference.


                                     Page 4

<PAGE>   5

(10)(a) Rollins Environmental Services, Inc. 1982 Incentive Stock Option Plan
filed with Amendment No. 1 to the Company's Registration Statement No. 2-84139
on Form S-1 dated June 24, 1983 and incorporated herein by reference.

(10)(b) Rollins Environmental Services, Inc. 1993 Stock Option Plan filed with
the Company's Proxy Statement for the Annual Meeting of Shareholders held
January 28, 1994 and incorporated herein by reference.

(10)(c) Laidlaw Environmental Services, Inc. 1997 Stock Option Plan, filed as
Exhibit 4.4 to the Company's Registration Statement on Form S-8 dated December
10, 1997 and incorporated herein by reference.

(10)(d) Laidlaw Environmental Services, Inc. Director's Stock Option Plan, filed
as Exhibit 4.5 to the Company's Registration Statement on Form S-8 dated
December 10, 1997 and incorporated herein by reference.

(10)(e) Stock Purchase Agreement dated February 6, 1997 among the Registrant,
Laidlaw Inc., and Laidlaw Transportation, Inc. included as an appendix to the
Definitive Proxy Statement on Form DEF 14A filed on May 1, 1997 and incorporated
herein by reference.

(10)(f) Management Incentive Plan for fiscal year 1998, filed as Exhibit 10(f)
to the Registrant's 10-Q for the quarter ended November 30, 1997, and
incorporated herein by reference.

(10)(g) Laidlaw Environmental Services, Inc. U.S. Supplemental Executive
Retirement Plan filed as Exhibit 10(g) to the Registrant's 10-Q for the quarter
ended November 30, 1997, and incorporated herein by reference.

(11)    Statement of Computation of Per Share Earnings.

(27)    Financial Data Schedule.

(b)     Reports on Form 8-K.

The Company filed a Current Report on Form 8-K, dated December 8, 1997, which
contained Item 5 related to a press release publicizing the decision of the
United States District Court for the Northern District of Illinois to order
Safety-Kleen Corp. to comply with its obligations under the Wisconsin control
share acquisition statute by promptly calling a meeting of shareholders.

The Company filed a Current Report on Form 8-K, dated December 19, 1997, which
contained Item 5 related to a press release publicizing the sale of its
municipal solid waste landfill in Carbon County, Utah to Allied Waste
Industries, Inc.

The Company filed a Current Report on Form 8-K/A, dated December 31, 1997, which
amended the Current Report on Form 8-K, dated November 5, 1997 which contained
Item 5 related to a press release publicizing the intent to file documents with
the Securities and Exchange Commission pertaining to an offer for Safety-Kleen
Corp.

                                     Page 5
<PAGE>   6

The Company filed a Current Report on Form 8-K/A, dated December 31, 1997, which
amended the Current Report on Form 8-K, dated November 14, 1997 which contained
Item 5 related to a press release publicizing the filing of a Form S-4.

The Company filed a Current Report on Form 8-K/A, dated December 31, 1997, which
amended the Current Report on Form 8-K, dated November 19, 1997 which contained
Item 5 related to a press release publicizing the response to the Safety-Kleen
Corp. lawsuit filed against it.

The Company filed a Current Report on Form 8-K/A, dated December 31, 1997, which
amended the Current Report on Form 8-K, dated November 21, 1997 which contained
Item 5 related to a press release publicizing a revised offer for Safety-Kleen
Corp.

The Company filed a Current Report on Form 8-K/A, dated December 31, 1997, which
amended the Current Report on Form 8-K, dated November 25, 1997 which contained
Item 5 related to a press release publicizing the filing of a Form S-4/A and the
filing of a lawsuit against Safety-Kleen Corp.

The Company filed a Current Report on Form 8-K, dated January 28, 1998, which
contained Item 5 related to a press release publicizing that early termination
of the statutory waiting period established under the Hart-Scott-Rodino review
process was granted as it concerned the Company's offer for Safety-Kleen Corp.
shares.

The Company filed a Current Report on Form 8-K, dated February 5, 1998, which
contained Item 5 related to a press release publicizing that the Company
remained committed to its Safety-Kleen stock offer and announcing a Court
decision relating to the lawsuit between the Company and Safety-Kleen Corp.

The Company filed a Current Report on Form 8-K, dated February 9, 1998, which
contained Item 5 related to a press release publicizing a report released by
Institutional Shareholder Services relating to the Company's offer for
Safety-Kleen Corp.
shares.

The Company filed a Current Report on Form 8-K, dated February 9, 1998, which
contained Item 5 related to a press release publicizing its advertisement in the
Wall Street Journal concerning the Safety-Kleen Corp. shareholder vote on the
Philip Services Corp. merger.

The Company filed a Current Report on Form 8-K, dated February 11, 1998, which
contained Item 5 related to a press release publicizing the exchange ratio for
purposes of its offer to purchase Safety-Kleen Corp. shares.

The Company filed a Current Report on Form 8-K, dated February 17, 1998, which
contained Item 5 related to a press release publicizing the upcoming expiration
of its offer to purchase outstanding shares of Safety-Kleen Corp.

The Company filed a Current Report on Form 8-K, dated February 17, 1998, which
contained Item 5 related to a press release publicizing the number of shares of
Safety-Kleen Corp. tendered to the Company and announcing the extension of its
offer.

The Company filed a Current Report on Form 8-K, dated February 18, 1998, which
contained Item 5 related to a press release publicizing the further extension of
its offer to purchase Safety-Kleen Corp. shares.


                                     Page 6
<PAGE>   7

The Company filed a Current Report on Form 8-K, dated February 20, 1998, which
contained Item 5 related to a press release publicizing that the Company's
shareholders had approved the authorization of additional common shares and the
issuance of shares in connection with the Company's offer to purchase
Safety-Kleen Corp. shares.

The Company filed a Current Report on Form 8-K, dated February 24, 1998, which
contained Item 5 related to a press release publicizing the exchange ratio for
purposes of the Company's offer to purchase Safety-Kleen Corp. shares.

The Company filed a Current Report on Form 8-K/A, dated February 24, 1998, which
amended the Current Report on Form 8-K, dated February 24, 1998 which contained
Item 5 related to a press release publicizing the exchange ratio for purposes of
the Company's offer to purchase Safety-Kleen Corp. shares.

The Company filed a Current Report on Form 8-K, dated February 25, 1998, which
contained Item 5 related to a press release publicizing the Company's desire
that Safety-Kleen Corp. shareholders vote against the Philip Group merger
proposal on February 25, 1998.

The Company filed a Current Report on Form 8-K, dated February 26, 1998, which
contained Item 5 related to a press release publicizing the further extension of
its exchange offer to purchase Safety-Kleen Corp. shares and further publicizing
its intent to commence the process to seek injunctive relief in Chicago Federal
Court to remove the obstacles to completion of its offer purchase Safety-Kleen
Corp. shares.


                                     Page 7
<PAGE>   8





                                   SIGNATURES

       Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.



   DATE: July 17, 1998                 LAIDLAW ENVIRONMENTAL SERVICES, INC.
                                       ------------------------------------
                                                    (Registrant)



                                              /s/Kenneth W. Winger
                                       -------------------------------------
                                                 Kenneth W. Winger
                                       President and Chief Executive Officer



                                               /s/Paul R. Humphreys
                                         ---------------------------------
                                                  Paul R. Humphreys
                                         Senior Vice President-Finance and
                                                  Chief Financial Officer


                                     Page 8
<PAGE>   9


                                INDEX TO EXHIBITS

(3)(a) Restated Certificate of Incorporation of the Company dated May 13, 1997
and Amendment to Certificate of Incorporation dated May 15, 1997 filed as
Exhibit 3(a) to the Registrant's Form 10-Q for the Quarter ended May 31, 1997
and incorporated herein by reference.

(3)(a)(i) Certificate of Correction Filed to Correct a Certain Error in the
Restated and Amended Certificate of Incorporation of the Company dated October
15, 1997 filed as Exhibit (3)(a)(i) to the Registrant's Form 10-K for the Year
ended August 31, 1997, and incorporated herein by reference.

(3)(a)(ii) Certificate of Amendment of Restated Certificate of Incorporation of
the Company dated February 19, 1998.

(3)(b) Amended and Restated Bylaws of the Company filed as Exhibit 4(ii) to the
Registrant's Current Report on Form 8-K dated July 29, 1997 and incorporated
herein by reference.

(4)(a) Rights Agreement dated as of June 14, 1989 between the Company and First
Chicago Trust Company as successor to Registrar and Transfer Company, as Rights
Agent filed as Exhibit 4(e) to the Registrant's Current Report on Form 8-K filed
on June 13, 1995 and incorporated herein by reference.

(4)(b) Amendment No. 1 dated as of March 31, 1995 to the Rights Agreement
between the Company and First Chicago Trust Company as successor to Registrar
and Transfer Company, as Rights Agent filed as Exhibit 4(f) to the Registrant's
Current Report on Form 8-K on June 13, 1995 and incorporated herein by
reference.

(4)(c) Amendment No. 2 dated as of April 30, 1997 to the Rights Agreement
between the Company and First Chicago Trust Company as successor to Registrar
and Transfer Company, as Rights Agent, filed as Exhibit 4(c) to the Registrant's
Form 10-Q for the quarter ended November 30, 1997, and incorporated herein by
reference.

(4)(d) Credit Agreement among Laidlaw Chem-Waste, Inc., Laidlaw Environmental
Services (Canada) Ltd., Toronto Dominion (Texas) Inc., The Toronto-Dominion
Bank, TD Securities (USA) Inc., the Bank of Nova Scotia, NationsBank, N.A. and
The First National Bank of Chicago and NationsBank, N.A. as Syndication Agent
dated as of May 9, 1997, filed as Exhibit 4(c) to the Registrant's Form 10-Q for
the Quarter ended May 31, 1997, and incorporated herein by reference.

(4)(e) $350,000,000 5% Subordinated Convertible Pay-In-Kind Debenture due 2009
issued by Registrant on May 15, 1997 to Laidlaw Transportation, Inc. the form of
which was included as an appendix to the Registrant's Definitive Proxy Statement
on Form DEF 14A, filed on May 1, 1997 and incorporated herein by reference.

(4)(f) Registration Rights Agreement dated May 15, 1997 between Registrant,
Laidlaw Transportation, Inc. and Laidlaw Inc. included as an appendix to the
Registrant's Definitive Proxy Statement on Form DEF 14A, the form of which was
filed on May 1, 1997 and incorporated herein by reference.

(4)(g) Indenture dated as of May 1, 1993 between the Industrial Development
Board of the Metropolitan Government of Nashville and Davidson County
(Tennessee) and NationsBank of Tennessee, N.A., filed as 


                                     Page 9
<PAGE>   10

Exhibit 4(f) to the Registrant's Form 10-Q for the Quarter ended May 31, 1997,
and incorporated herein by reference.

(4)(h) Indenture of Trust dated as of February 1, 1995 between Carbon County,
Utah and West One Bank, Utah, now known as U.S. Bank, as Trustee, filed as
Exhibit 4(g) to the Registrant's Form 10-Q for the Quarter ended May 31, 1997,
and incorporated herein by reference.

(4)(i) Indenture of Trust dated as of August, 1995 between Tooele County, Utah
and West One Bank, Utah, now known as U.S. Bank, as Trustee, filed as Exhibit
4(h) to the Registrant's form 10-Q for the Quarter ended May 31, 1997, and
incorporated herein by reference.

(4)(j) Indenture of Trust dated as of July 1, 1997 between Carbon County, Utah
and U.S. Bank, a national banking association, as Trustee, filed as Exhibit 4(i)
to the Registrant's Form 10-Q for the Quarter ended May 31, 1997, and
incorporated herein by reference.

(4)(k) Indenture of Trust dated as of July 1, 1997 between Tooele County, Utah
and U.S. Bank, a national banking association, as Trustee, filed as Exhibit 4(j)
to the Registrant's Form 10-Q for the Quarter ended May 31, 1997, and
incorporated herein by reference.

(4)(l) Indenture of Trust dated as of July 1, 1997 between California Pollution
Control Financing Authority and U.S. Bank, a national banking association, as
Trustee, filed as Exhibit 4(k) to the Registrant's Form 10-Q for the Quarter
ended May 31, 1997, and incorporated herein by reference.

(4)(m) Stock Purchase Agreement between Westinghouse Electric Corporation
(Seller) and Rollins Environmental Services, Inc. (Buyer) for National Electric,
Inc. dated March 7, 1995 filed as Exhibit 2 to the Registrant's Current Report
on Form 8-K filed on June 13, 1995 and incorporated herein by reference.

(4)(n) Second Amendment to Stock Purchase Agreement (as referenced in Exhibit
(4)(m) above, dated May 15, 1997 among Westinghouse Electric Corporation,
Rollins Environmental Services, Inc. and Laidlaw Inc., filed as Exhibit 4(m) to
the Registrant's Form 10-Q for the Quarter ended May 31, 1997, and incorporated
herein by reference.

(4)(o) Promissory Note dated May 15, 1997 for $60,000,000 from Laidlaw
Environmental Services, Inc. to Westinghouse Electric Corporation, filed as
Exhibit 4(n) to the Registrant's Form 10-Q for the Quarter ended May 31, 1997,
and incorporated herein by reference.

(4)(p) Guaranty Agreement dated May 15, 1997 by Laidlaw Inc. to Westinghouse
Electric Corporation guaranteeing Promissory Note dated May 15, 1997 (as
referenced in Exhibit (4)(o)) from Laidlaw Environmental Services, Inc. to
Westinghouse Electric Corporation, filed as Exhibit 4(o) to the Registrant's
Form 10-Q for the Quarter ended May 31, 1997, and incorporated herein by
reference.

(10)(a) Rollins Environmental Services, Inc. 1982 Incentive Stock Option Plan
filed with Amendment No. 1 to the Company's Registration Statement No. 2-84139
on Form S-1 dated June 24, 1983 and incorporated herein by reference.

(10)(b) Rollins Environmental Services, Inc. 1993 Stock Option Plan filed with
the Company's Proxy Statement for the Annual Meeting of Shareholders held
January 28, 1994 and incorporated herein by 


                                    Page 10
<PAGE>   11

reference.

(10)(c) Laidlaw Environmental Services, Inc. 1997 Stock Option Plan, filed as
Exhibit 4.4 to the Company's Registration Statement on Form S-8 dated December
10, 1997 and incorporated herein by reference.

(10)(d) Laidlaw Environmental Services, Inc. Director's Stock Option Plan, filed
as Exhibit 4.5 to the Company's Registration Statement on Form S-8 dated
December 10, 1997 and incorporated herein by reference.

(10)(e) Stock Purchase Agreement dated February 6, 1997 among the Registrant,
Laidlaw Inc., and Laidlaw Transportation, Inc. included as an appendix to the
Definitive Proxy Statement on Form DEF 14A filed on May 1, 1997 and incorporated
herein by reference.

(10)(f) Management Incentive Plan for fiscal year 1998, filed as Exhibit 10(f)
to the Registrant's 10-Q for the quarter ended November 30, 1997, and
incorporated herein by reference.

(10)(g) Laidlaw Environmental Services, Inc. U.S. Supplemental Executive
Retirement Plan filed as Exhibit 10(g) to the Registrant's 10-Q for the quarter
ended November 30, 1997, and incorporated herein by reference.

(11)    Statement of Computation of Per Share Earnings.

(27)    Financial Data Schedule.



                                    Page 11