Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities
Net income (loss)	$ 39,759	$ (4,907)	$ 24,934
Adjustments to reconcile net income (loss) to net cash from operating activities:
Accretion of asset retirement obligations	615	570	511
Depreciation and amortization	26,205	20,912	19,521
Amortization of debt issuance costs	214	58	58
Stock-based compensation	5,260	4,140	4,060
Other income - employee retention tax credit	(5,407)
Other income - PPP Loan		(8,444)
Deferred income taxes	4,644	(3,503)	5,156
Changes in operating assets and liabilities:
Accounts receivable	(24,154)	(1,043)	(8,527)
Prepaid expenses and other current assets	5,519	986	723
Inventories	(3,844)	3,314	(1,076)
Other assets and liabilities	1,124	(1,270)	689
Accounts payable	(1,820)	2,753	(7,313)
Accrued expenses	5,225	(254)	3,646
Net cash from operating activities	53,340	13,312	42,382
Cash flow from investing activities:
Purchases of property, plant and equipment	(29,466)	(24,753)	(45,722)
Acquisition of Amonate assets	(30,147)
Net cash from investing activities	(59,613)	(24,753)	(45,722)
Cash flows from financing activities
Proceeds from PPP Loan		8,444
Proceeds from borrowings	54,368	50,043	73,750
Payments of debt issuance cost	(2,356)
Repayments of borrowings	(26,300)	(45,598)	(70,335)
Repayments of financed insurance payable	(862)	(1,382)	(570)
Repayments of financing leased equipment	(1,942)
Restricted stock surrendered for withholding taxes payable	(539)	(221)	(20)
Net cash from financing activities	22,369	11,286	2,825
Net change in cash and cash equivalents and restricted cash	16,096	(155)	(515)
Cash and cash equivalents and restricted cash, beginning of period	6,710	6,865	7,380
Cash and cash equivalents and restricted cash, end of period	22,806	6,710	6,865
Supplemental cash flow information:
Cash paid for interest	1,601	1,095	999
Cash paid for taxes	9	19
Non-cash investing and financing activities:
Leased assets obtained under new financing leases	10,002
Dividend accrued not paid	2,501
Capital expenditures included in accounts payable and accrued expenses	6,652	1,228	2,902
Financed insurance	280	1,588	939
Additional asset retirement obligations incurred	$ 6,840	$ 86	$ 516