The opinion of the court was delivered by: GESELL
GERHARD A. GESELL, UNITED STATES DISTRICT JUDGE.
FINDINGS OF FACT AND CONCLUSIONS OF LAW
After the Court had considered two separate sets of cross-motions for summary judgment and each time had found material facts in dispute on the main issue, see Memorandum and Order dated September 21, 1989; Memorandum and Order dated July 12, 1990, plaintiff Trusts brought this ERISA case before the Court for a full evidentiary bench trial on October 22, 1990. Now the decisive issue previously considered is again presented on the trial record after full argument. The Trusts contend that defendant United Parcel Service ("UPS") has underpaid contributions to the Pension Trust pursuant to 1982 and 1987 collective bargaining agreements between UPS and Teamsters Local 639 by systematic error in calculating the weeks for which contributions are due. The Trusts have failed to carry their burden of establishing their claim by a preponderance of the evidence.
The Court now makes the following findings of fact and conclusions of law.
(1) Defendant UPS is an employer pursuant to ERISA, 29 U.S.C. § 1002(5).
(2) Plaintiff Trusts are multiemployer pension and health employee benefit plans pursuant to ERISA, 29 U.S.C. § 1002(1)-(3), (37).
(3) The calculation of UPS's contributions to the Trusts since 1964 has been governed by a series of collective bargaining agreements entered into between Local 639 and UPS. Since the 1960's, there has been a variety of different provisions governing contributions for vacations in the contracts of different Teamster Locals, as well as wide variety in the way identical contract language has been interpreted. As the size and coverage of Local 639's bargaining unit and personnel has changed, there has been considerable confusion as to the meaning and effect of provisions dealing with UPS contributions to the Trusts.
(5) The Court has already held that the disputed contract language is ambiguous. Memorandum of September 21, 1989, at 3. Therefore, the Court is obligated to consider extrinsic evidence as to the meaning of the provision, including past practice, related agreements, and bargaining history. See United Mine Workers of America 1950 Benefit Plan and Trust v. Bituminous Coal Operators Ass'n, Inc., 283 U.S. App. D.C. 163, 898 F.2d 177, 181 (D.C.Cir. 1990).
(6) UPS has never paid contributions to the Pension Trust for full vacation weeks.
(7) The Trusts audited UPS payroll contribution records repeatedly from 1965 through 1979 and never found any discrepancies with respect to payments for vacations.
(8) A 1984 audit found discrepancies with respect to vacation week contributions. The Trusts notified UPS of the results, and UPS responded that it would not pay contributions for full vacation weeks. The Trusts brought suit against UPS in this Court in Civil Action No. 85-2313, and the case was settled in 1986.
(9) A May 1987 audit report found no discrepancies between UPS's payments and its obligations.
(10) In June 1987, calculations of an individual union member's pension showed that UPS was not contributing to the Pension ...