13.	Pension Plans and Other Postretirement Benefits

The following table provides the components of net periodic benefit costs:

	Pension Benefits
	Three Months Ended						Nine Months Ended
	June 30,			June 24,			June 30,			June 24,
	2018			2017			2018			2017
Interest cost	$	944		$	1,041		$	2,832		$	3,123
Expected return on plan assets		(473	)		(537	)		(1,420	)		(1,611	)
Amortization of net loss		920			1,301			2,762			3,901
Net periodic benefit cost	$	1,391		$	1,805		$	4,174		$	5,413

	Postretirement Benefits
	Three Months Ended						Nine Months Ended
	June 30,			June 24,			June 30,			June 24,
	2018			2017			2018			2017
Interest cost	$	69		$	96		$	208		$	288
Amortization of prior service credits		(124	)		—			(374	)		—
Amortization of net (gain)		(163	)		(98	)		(491	)		(292	)
Net periodic benefit cost	$	(218	)	$	(2	)	$	(657	)	$	(4	)

The Partnership expects to contribute approximately $4,764 to the defined benefit pension plan during fiscal 2018, of which $3,839 was contributed during the nine months ended June 30, 2018. The projected annual contribution requirements related to the Partnership’s postretirement health care and life insurance benefit plan for fiscal 2018 is $1,243, of which $847 was contributed during the nine months ended June 30, 2018.

The Partnership contributes to multi-employer pension plans (“MEPPs”) in accordance with various collective bargaining agreements covering union employees. As one of the many participating employers in these MEPPs, the Partnership is responsible with the other participating employers for any plan underfunding. As of June 30, 2018 and September 30, 2017, the Partnership’s estimated obligation to these MEPPs was $22,773 and $23,665, respectively, as a result of its voluntary full withdrawal from certain MEPPs.