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, 2019 and 2018 (in thousands):

Depreciation expense for 2019, 2018 and 2017 was $9.6 million, $10.4 million  and $12.7 million, respectively. The decrease in depreciation expense for 2019 was due to assets becoming fully depreciated. The decrease in expense for 2018 was due to classifying our South Texas Properties as assets held for sale during the first quarter of 2017 and suspending the recognition of depreciation expense for those assets.

Leased Facilities and Equipment

As discussed further in Note 1, in the first quarter 2019, we adopted ASU 2016-02, “Leases.” Upon adoption, we recorded operating lease assets and lease liabilities of approximately $7.1 million and $5.2 million, respectively, at January 1, 2019. Included in our lease asset was an intangible asset of $1.9 million associated with two favorable lease obligations recorded in connection with a former acquisition, which was reclassified as a lease asset under ASU 2016-02. At December 31, 2019, our significant leases subject to long-term agreements were as follows:

During the fourth quarter 2019, we determined that it was no longer reasonably certain that we would exercise the renewal options for our Jennings Yard and Lake Charles Yard, and accordingly, we remeasured our lease obligations for these facilities to exclude the lease renewal options, which resulted in a reduction to our operating lease assets and lease liabilities of $2.5 million.  At December 31, 2019, our lease asset, current lease liability and long-term lease liability were $1.9 million, $0.5 million and $2.1 million, respectively. See Note 3 for discussion of our lease asset impairments recorded during 2019.

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

Total lease expense, to include lease asset amortization expense and expense for leases that are twelve months or less, for 2019, 2018 and 2017, was, $1.8 million, $1.9 million and $2.0 million, respectively, related to our leased facilities and equipment.  Cash paid for interest and lease expense for 2019 was $2.0 million.

The discount rate used to determine the present value of our lease liabilities was based on the interest rate on our Credit Agreement adjusted for terms similar to that of our leased properties.  At December 31, 2019, our weighted-average remaining lease term was approximately 4.6 years and the weighted-average discount rate used to derive our lease liability was 6.75%.