<PAGE>
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
INFORMATION STATEMENT PURSUANT TO RULES 13d-1 AND 13d-2
UNDER THE SECURITIES AND EXCHANGE ACT OF 1934
(Amendment No. 5) *
Roy F. Weston, Inc.
- --------------------------------------------------------------------------------
(Name of Issuer)
Series A Common Stock
- --------------------------------------------------------------------------------
(Title of Class of Securities)
961137106
- --------------------------------------------------------------------------------
(CUSIP Number)
- -------------------------
* The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter
disclosures provided in a prior cover page.
The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).
(Continued on following page(s))
Page 1 of 8 Pages
<PAGE>
CUSIP No. 961137106 13G Page 2 of 8 Pages
--------- --- ---
- -------------------------------------------------------------------------------
1 NAME OF REPORTING PERSON
S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON
The TCW Group, Inc.
- -------------------------------------------------------------------------------
2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
(a) / /
(b) /X/
- -------------------------------------------------------------------------------
3 SEC USE ONLY
- -------------------------------------------------------------------------------
4 CITIZENSHIP OR PLACE OF ORGANIZATION
Nevada corporation
- -------------------------------------------------------------------------------
NUMBER OF 5 SOLE VOTING POWER
SHARES 760,400
BENEFICIALLY ------------------------------------------------------------
OWNED BY 6 SHARED VOTING POWER
EACH -0-
REPORTING ------------------------------------------------------------
PERSON 7 SOLE DISPOSITIVE POWER
WITH 760,400
------------------------------------------------------------
8 SHARED DISPOSITIVE POWER
-0-
- -------------------------------------------------------------------------------
9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
760,400
- -------------------------------------------------------------------------------
10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES
CERTAIN SHARES*
/ /
- -------------------------------------------------------------------------------
11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)
9.9% (see response to Item 4)
- -------------------------------------------------------------------------------
12 TYPE OF REPORTING PERSON*
HC/CO
- -------------------------------------------------------------------------------
*SEE INSTRUCTIONS BEFORE FILLING OUT!
<PAGE>
CUSIP No. 961137106 13G Page 3 of 8 Pages
--------- --- ---
- -------------------------------------------------------------------------------
1 NAME OF REPORTING PERSON
S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON
Robert Day
- -------------------------------------------------------------------------------
2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
(a) / /
(b) /X/
- -------------------------------------------------------------------------------
3 SEC USE ONLY
- -------------------------------------------------------------------------------
4 CITIZENSHIP OR PLACE OF ORGANIZATION
United States Citizen
- -------------------------------------------------------------------------------
NUMBER OF 5 SOLE VOTING POWER
SHARES 760,400
BENEFICIALLY ------------------------------------------------------------
OWNED BY 6 SHARED VOTING POWER
EACH -0-
REPORTING ------------------------------------------------------------
PERSON 7 SOLE DISPOSITIVE POWER
WITH 760,400
------------------------------------------------------------
8 SHARED DISPOSITIVE POWER
-0-
- -------------------------------------------------------------------------------
9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING
PERSON
760,400
- -------------------------------------------------------------------------------
10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES
CERTAIN SHARES*
/ /
- -------------------------------------------------------------------------------
11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)
9.9% (see response to Item 4)
- -------------------------------------------------------------------------------
12 TYPE OF REPORTING PERSON*7
HC/IN
- -------------------------------------------------------------------------------
*SEE INSTRUCTIONS BEFORE FILLING OUT!
<PAGE>
Page 4 of 8 Pages
Item 1(a). Name of Issuer:
Roy F. Weston, Inc.
Item 1(b). Address of Issuer's Principal Executive Offices:
1 Weston Way
West Chester, PA 19380-1499
Item 2(a). Name of Persons Filing:
Item 2(b). Address of Principal Business Office:
Item 2(c). Citizenship:
The TCW Group, Inc.
865 South Figueroa Street
Los Angeles, CA 90017
(Nevada Corporation)
Robert Day
200 Park Avenue, Suite 2200
New York, New York 10166
(United States Citizen)
Item 2(d). Title of Class of Securities:
Series A Common Stock
Item 2(e). CUSIP Number:
961137106
<PAGE>
Page 5 of 8 Pages
Item 3. If this statement is filed pursuant to Rules 13d-1(b), or 13d-2(b),
check whether the person filing is a:
(a) [ ] Broker or Dealer registered under Section 15 of the Act:
Not applicable
(b) [ ] Bank as defined in Section 3(a)(6) of the Act:
Not applicable
(c) [ ] Insurance Company as defined in Section 3(a)(19) of the Act:
Not applicable
(d) [ ] Investment Company registered under Section 8 of the Investment
Company Act:
Not applicable
(e) [ ] Investment Adviser registered under Section 203 of the Investment
Advisers Act of 1940:
Not applicable
(f) [ ] Employee Benefit Plan, Pension Fund which is subject to the
provisions of the Employee Retirement Income Security Act of 1974
or Endowment Fund (SEE 13d-1(b)(1)(ii)(F)):
Not applicable
(g) [X] Parent Holding Company, in accordance with Rule 13d-1(b)(ii)(G)
(SEE Item 7):
The TCW Group, Inc.
Robert Day (individual who may be deemed to control The TCW
Group, Inc. and other holders of the Series A Common
Stock of the issuer)
(h) [ ] Group, in accordance with Rule 13d-1(b)(1)(ii)(H):
Not applicable.
<PAGE>
Page 6 of 8 Pages
Item 4. Ownership **
THE TCW GROUP, INC.
(a) Amount beneficially owned: 760,400
(b) Percent of class: 9.9%
(c) Number of shares as to which such person has:
(i) Sole power to vote or to direct the vote: 760,400
(ii) Shared power to vote or to direct the vote: none.
(iii) Sole power to dispose or direct the disposition of: 760,400
(iv) Shared power to dispose or to direct the disposition of:
none.
ROBERT DAY ***
(a) Amount beneficially owned: 760,400
(b) Percent of class: 9.9%
(c) Number of shares as to which such person has:
(i) Sole power to vote or to direct the vote: 760,400
(ii) Shared power to vote or to direct the vote: none.
(iii) Sole power to dispose or direct the disposition of: 760,400
(iv) Shared power to dispose or to direct the disposition of:
none.
- ----------------------------
** The filing of this Schedule 13G shall not be construed as an admission
that the reporting person or any of its affiliates is, for the purposes of
Section 13(d) or 13(g) of the Securities Exchange Act of 1934, the beneficial
owner of any securities covered by this Schedule 13G. In addition, the filing
of this Schedule 13G shall not be construed as an admission that the reporting
person or any of its affiliates is the beneficial owner of any securities
covered by this Schedule 13G for any other purposes than Section 13(d) of the
Securities Exchange Act of 1934.
*** Shares reported for Robert Day include shares reported for The TCW Group,
Inc.
<PAGE>
Page 7 of 8 Pages
Item 5. Ownership of Five Percent or Less of a Class.
Not applicable.
Item 6. Ownership of More than Five Percent on Behalf of Another Person.
Various persons other than as described in Item 4, including the TCW
Value Added Fund, have the right to receive or the power to direct the
receipt of dividends from, or the proceeds from the sale of, the
Series A Common Stock of Roy F. Weston, Inc.
Item 7. Identification and Classification of the Subsidiary Which Acquired the
Security Being Reported on by the Parent Holding Company.
SEE Exhibit A.
Item 8. Identification and Classification of Members of the Group.
Not applicable. SEE Exhibits A and B.
Item 9. Notice of Dissolution of Group.
Not applicable.
Item 10. Certification.
Because this statement is filed pursuant to Rule 13d-1(b), the following
certification is included:
By signing below I certify that, to the best of my knowledge and belief,
the securities referred to above were acquired in the ordinary course of
business and were not acquired for the purpose of and do not have the
effect of changing or influencing the control of the issuer of such
securities and were not acquired in connection with or as a participant in
any transaction having such purpose or effect.
<PAGE>
Page 8 of 8 Pages
SIGNATURE
After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.
Dated this 4th day of February, 1998.
The TCW Group, Inc.
By: /s/ Mohan V. Phansalkar
-------------------------
Mohan V. Phansalkar
Authorized Signatory
Robert Day
By: /s/ Mohan V. Phansalkar
-------------------------
Mohan V. Phansalkar
Under Power of Attorney dated January 30,
1996, on File with Schedule 13G Amendment
Number 1 for Matrix Service Co. dated January
30, 1996.
<PAGE>
EXHIBIT A
RELEVANT SUBSIDIARIES OF PARENT HOLDING COMPANY
PART A: TCW ENTITIES
PARENT HOLDING COMPANY:
The TCW Group, Inc.
Robert Day (an individual who may be deemed to control The TCW Group,
Inc.)
RELEVANT SUBSIDIARIES THAT ARE PERSONS DESCRIBED IN RULE 13d-1(b):
(i) Trust Company of the West, a California corporation and a bank as
defined in Section 3(a)(6) of the Securities Exchange Act of 1934.
(ii) TCW Asset Management Company, a California corporation and an
Investment Adviser registered under Section 203 of the Investment Advisers
Act of 1940.
Note: No Series A Common Stock of Roy F. Weston, Inc. is held directly
by The TCW Group, Inc. Other than the indirect holdings of The
TCW Group, Inc. no Series A Common Stock of Roy F. Weston, Inc.
is held directly or indirectly by Robert Day, an individual who
may be deemed to control The TCW Group, Inc.
PART B: NON TCW ENTITIES
PARENT HOLDING COMPANY:
Robert Day (an individual who may be deemed to control the
holders described below which are not subsidiaries of The TCW
Group, Inc.)
RELEVANT SUBSIDIARIES THAT ARE PERSONS DESCRIBED IN RULE 13d-1(b):
Oakmont Corporation, a California corporation and an Investment
Adviser registered under Section 203 of the Investment Advisers
Act of 1940.
Cypress International Partners Limited, a British Virgin Islands
corporation and an Investment Adviser registered under Section
203 of the Investment Advisers Act of 1940.
A-1
<PAGE>
EXHIBIT B
JOINT FILING AGREEMENT
The undersigned acknowledge and agree that the foregoing statement on
Schedule 13G is filed on behalf of each of the undersigned and that all
subsequent amendments to this statement on Schedule 13G shall be filed on behalf
of each of the undersigned without the necessity of filing additional joint
acquisition statements. The undersigned acknowledge that each shall be
responsible for the timely filing of such amendments, and for the completeness
and accuracy of the information concerning him or it contained therein, but
shall not be responsible for the completeness and accuracy of the information
concerning the other, except to the extent that he or it knows or has reason to
believe that such information is accurate.
Dated: February 4, 1998
The TCW Group, Inc.
By: /s/ Mohan V. Phansalkar
---------------------------
Mohan V. Phansalkar
Authorized Signatory
Robert Day
By: /s/ Mohan V. Phansalkar
---------------------------
Mohan V. Phansalkar
Under Power of Attorney dated January 30,
1996, on File with Schedule 13G Amendment
Number 1 for Matrix Service Co. dated January
30, 1996.
B-1
