SHORT-TERM AND LONG-TERM DEBT - Summary of short-term and long-term debt (Narrative) (Details) - USD ($)	9 Months Ended	12 Months Ended
	Jun. 30, 2026	Sep. 30, 2025	Jun. 28, 2026	Apr. 30, 2023	Apr. 27, 2020	Apr. 07, 2020
SHORT-TERM AND LONG-TERM DEBT
Fair value of debt	$ 28,900,000	$ 42,800,000
Line of credit payable to bank, final payment due by June 28, 2028
SHORT-TERM AND LONG-TERM DEBT
Interest rate at period end (as a percent)	6.75%	7.50%
Maximum capacity			$ 30,000,000
Equipment line of credit, Final payment due February 2028
SHORT-TERM AND LONG-TERM DEBT
Interest rate, fixed (as a percent)	7.25%	7.25%
Maximum capacity	$ 9,300,000	$ 9,300,000
Monthly or annual installments	$ 202,809	$ 202,809
Paycheck Protection Program loans from Small Business Administration
SHORT-TERM AND LONG-TERM DEBT
Interest rate, fixed (as a percent)	1.00%	1.00%
Debt instrument face amount				$ 9,800,000	$ 9,800,000	$ 13,100,000
Term note payable to United Bank, WV Pipeline acquisition, final payment due by March 25, 2026
SHORT-TERM AND LONG-TERM DEBT
Interest rate, fixed (as a percent)	4.25%	4.25%
Monthly or annual installments	$ 64,853	$ 64,853
Notes Payable To Finance Companies Due July 2026 through February 2030
SHORT-TERM AND LONG-TERM DEBT
Monthly or annual installments	$ 350,000	$ 244,000
Notes Payable To Finance Companies Due July 2026 through February 2030 | Minimum
SHORT-TERM AND LONG-TERM DEBT
Interest rate, fixed (as a percent)	0.00%	0.00%
Notes Payable To Finance Companies Due July 2026 through February 2030 | Maximum
SHORT-TERM AND LONG-TERM DEBT
Interest rate, fixed (as a percent)	6.00%	6.00%
Note payable to United Bank Tribute acquisition finance final payment due by December 2030
SHORT-TERM AND LONG-TERM DEBT
Interest rate, fixed (as a percent)	6.90%
Monthly or annual installments	$ 272,016
Notes payable to bank, final payment due November 2034
SHORT-TERM AND LONG-TERM DEBT
Interest rate, fixed (as a percent)	4.82%
Monthly or annual installments	$ 7,848
Notes payable to bank, final payment due by October 2027
SHORT-TERM AND LONG-TERM DEBT
Interest rate, fixed (as a percent)	6.00%
Monthly or annual installments	$ 59,932
Convertible equipment line of credit
SHORT-TERM AND LONG-TERM DEBT
Interest rate, fixed (as a percent)	8.50%	8.50%
Maximum capacity	$ 5,000,000	$ 5,000,000
Variable interest rate on line of credit (as a percent)	2.75%	2.75%
Debt term	48 months	48 months
Unsecured notes payable to Joe and Cathy Rigney, due September 30, 2030
SHORT-TERM AND LONG-TERM DEBT
Interest rate, fixed (as a percent)	5.00%	5.00%
Monthly or annual installments	$ 500,000	$ 500,000
Debt term	5 years	5 years
Fair value of debt		$ 462,950
Notes payable to David Bolton and Daniel Bolton due final payment December 31, 2025
SHORT-TERM AND LONG-TERM DEBT
Interest rate, fixed (as a percent)		3.25%
Monthly or annual installments		$ 500,000
Note payable to United Bank, Tri-State Paving acquisition, final payment due by June 1, 2027
SHORT-TERM AND LONG-TERM DEBT
Interest rate, fixed (as a percent)	4.50%	4.50%
Monthly or annual installments	$ 129,910	$ 129,910
Notes payable to Corns Enterprises, final payment due April 29, 2026
SHORT-TERM AND LONG-TERM DEBT
Interest rate, fixed (as a percent)	3.50%	3.50%
REPLACED WITH US-GAAP Notes payable on annual installments	$ 250,000	$ 250,000
Fair value of debt	936,000
Debt instrument face amount	$ 1,000,000	$ 1,000,000