
<PAGE>   1
                                                                     EXHIBIT 5.1



                           [SNELL & SMITH LETTERHEAD]





                                  May 11, 1995



USA Waste Services, Inc.
5000 Quorum Drive, Suite 300
Dallas, Texas  75240

Gentlemen:

                 We have acted as counsel for USA Waste Services, Inc., an
Oklahoma corporation (the "Company"), in connection with the proposed offering
by the Company of approximately 28,000,000 shares of the common stock, $.01 par
value per share (the "Common Stock"), of the Company to be issued in connection
with the merger (the "Merger") of Chambers Acquisition Company, a Delaware
corporation and wholly-owned subsidiary of the Company, with and into Chambers
Development Company, Inc., a Delaware corporation ("Chambers").

                 In connection with such matters, we have examined among other
things, the Certificate of Incorporation and the By- Laws of the Company, the
corporate proceedings with respect to the offering of the Common Stock, the
Amended and Restated Plan and Agreement of Merger dated as of November 28, 1994
(the "Merger Agreement"), among the Company, Chambers, and Acquisition, and the
Registration Statement on Form S-4 filed by the Company with the Securities and
Exchange Commission for the registration of the Common Stock under the
Securities Act of 1933, as amended (the "Securities Act") (the Registration
Statement as amended at the time when it becomes effective being herein
referred to as the "Registration Statement").

                 We have assumed the genuineness and authenticity as all
signatures on all original documents, the authenticity of all documents
submitted to us as originals, the conformity to originals of all documents
submitted to us as copies, and the due authorization, execution, delivery, or
recordation of all documents where such due authorization, execution, delivery,
or recordation are prerequisites to the effectiveness thereof.

                 Based on the foregoing, and having regard for such legal
considerations as we deemed relevant, we are of the opinion (limited in all
respects to the internal laws of the State of Texas, the Oklahoma General
Corporation Law, and applicable federal law) that:
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USA Waste Services, Inc.
May 11, 1995
Page 2



                 1.       The Company is a corporation duly organized, validly
         existing, and in good standing under the laws of the State of
         Oklahoma.

                 2.       The shares of Common Stock proposed to be issued by
         the Company to the shareholders of Chambers, pursuant to the Merger,
         have been duly authorized for issuance, and subject to the
         Registration Statement becoming effective under the Securities Act,
         and to compliance with any applicable state securities laws, when
         issued in accordance with the terms of the Merger Agreement will be
         duly authorized, validly issued, fully paid, and non-assessable.

                 3.       The authorized capital of the Company consists of
         50,000,000 shares of Common Stock, of which, as of the date hereof,
         22,967,256 shares are issued and outstanding, and 10,000,000 shares of
         Preferred Stock, $.01 par value per share, none of which, as of the
         date hereof, are issued and outstanding.

                 We hereby consent to the filing of this opinion as an exhibit
to the Registration Statement and to the reference to us under "Legal Matters"
in the Joint Proxy Statement and Prospectus forming a part of the Registration
Statement.

                                                   Very truly yours,

                                                   SNELL & SMITH, A Professional
                                                     Corporation





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