4. PROPERTY, PLANT AND EQUIPMENT AND LEASED FACILITIES AND EQUIPMENT

Property, plant and equipment

Property, plant and equipment consisted of the following at December 31, 2020 and 2019 (in thousands):

Depreciation expense for 2020, 2019 and 2018 was $8.6 million, $9.6 million and $10.4 million, respectively. The decrease in depreciation expense for 2020 compared to 2019 was due to assets becoming fully depreciated and assets being impaired in the fourth quarter 2019. The decrease in depreciation expense for 2019 compared to 2018 was due to assets becoming fully depreciated.

Leased Facilities and Equipment

At December 31, 2020, our significant leases subject to long-term agreements were as follows:

At December 31, 2020, our lease asset, current lease liability and long-term lease liability were $1.7 million, $0.6 million and $2.0 million, respectively.  As discussed above, we do not intend to exercise the renewal options for our Jennings Yard and Lake Charles Yard, and accordingly, our lease obligations for these facilities exclude the lease renewal options.  See Note 3 for discussion of our lease asset impairments recorded during 2020 and 2019.

Future minimum payments under leases having initial terms of more than twelve months are as follows (in thousands):

Total lease expense for our leased facilities and equipment, which includes lease asset amortization expense and expense for leases with original terms that are twelve months or less, for 2020, 2019 and 2018, was $1.5 million, $1.8 million and $1.9 million, respectively.  Cash paid for interest and lease expense for 2020 and 2019 was $1.8 million and $2.0 million, respectively.

The discount rate used to determine the present value of our lease liabilities was based on the interest rate on our LC Facility adjusted for terms similar to that of our leased properties. At December 31, 2020, our weighted-average remaining lease term was approximately 4.0 years and the weighted-average discount rate used to derive our lease liability was 6.7%.