EXHIBIT 9

                               November 13, 1997



Mr. Donald W. Brinckman
Chairman & Chief Executive Officer
Safety-Kleen Corp.
1000 North Randall Road
Elgin, Illinois
USA 60123

Dear Mr. Brinckman:

     We continue to be frustrated at the lack of progress in engaging in
substantive dialogue with you due to your continuing insistence that we sign a
standstill agreement. We believe our offer of $14.00 in cash and 2.4 shares of
Laidlaw Environmental Services, Inc. common stock represents outstanding value
for your shareholders.

     The combination of our two companies is of compelling strategic importance
to both our shareholders. We have repeatedly sought to work with you in a
cooperative manner to achieve a mutually beneficial transaction. Unfortunately,
our efforts have come to naught.

     As we discussed in Chicago, under the securities laws we are required to
file a registration statement relating to our offer with the Securities and
Exchange Commission. We took that step today. As a courtesy, we are enclosing a
copy of these materials for you. As soon as we are permitted to so, we will make
our offer directly to Safety-Kleen Corp. shareholders. We strongly believe that
Safety-Kleen Corp. shareholders, the owners of the company to whom your Board
owes fiduciary duties, are the ones who should ultimately decide whether our
offer and the strategic benefits the combination promises are as compelling to
them as they are to us.

     As you will appreciate, in order for Safety-Kleen Corp. shareholders to
accept our offer, we must be assured that all antitakeover devices put in place
by your Board or otherwise applicable under Wisconsin law will not apply to our
offer. Accordingly, we hereby request that your Board amend your poison pill to
make it inapplicable to an acquisition of Safety-Kleen Corp. shares pursuant to
our offer, approve our acquisition of Safety-Kleen Corp. shares pursuant to our
offer for purposes of Section 180.1141 of the Wisconsin Statutes and take or
agree to take any other action necessary or appropriate to eliminate all
antitakeover devices.

     In addition, we are furnishing you with the resolution and notice
contemplated by Section 180.1150(4) of the Wisconsin Statutes. We request that,
as required by statute, your

 
Board call a special meeting of Safety-Kleen Corp. shareholders to vote on the
resolution and that such meeting be held no sooner than 30 nor later than 50
days from the date hereof. In this connection, we are enclosing a request that
you furnish us with a list of Safety-Kleen Corp. shareholders so that we can
communicate with them directly and solicit proxies for the special meeting.

     We do not take these actions lightly. Your failure to work with us leave us
no alternative. We remain hopeful your board, after due consideration, will
determine to engage us in negotiations that lead to a mutually beneficial merger
of our two outstanding companies.

                                        Yours very truly,


                                        /s/James R. Bullock
                                        James R. Bullock
                                        Chairman