v3.26.1
SEGMENT INFORMATION - Segment financial information (Details) - USD ($)
 3 Months Ended 6 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2026
Mar. 31, 2025
SEGMENT INFORMATION        
Gross profit $ 10,232,336 $ 77,860 $ 24,226,128 $ 10,341,442
Selling, general, and administrative expenses 9,173,925 8,170,087 18,254,952 16,787,708
Intangible asset amortization expenses     690,345 295,060
Corporate depreciation expense     6,724,766 5,586,230
Income (loss) from operations 1,058,411 (8,092,227) 5,971,176 (6,446,266)
Operating Segments        
SEGMENT INFORMATION        
Revenue 93,173,442 76,679,151 207,285,642 177,325,265
Segment direct operating expenses (excluding depreciation) 79,689,279 73,670,167 176,565,295 161,568,377
Direct depreciation expense 3,251,827 2,931,124 6,494,219 5,415,446
Gross profit $ 10,232,336 $ 77,860 $ 24,226,128 $ 10,341,442
Segment gross profit percentage 11.00% 0.10% 11.70% 5.80%
Selling, general, and administrative expenses $ 7,271,092 $ 6,556,611 $ 14,187,722 $ 13,081,264
Indirect depreciation expense 116,552 84,953 225,274 167,439
Intangible asset amortization expenses 284,403 141,476 690,345 266,285
Segment indirect operating expenses $ 7,672,047 $ 6,783,040 $ 15,103,341 $ 13,514,988
Segment operating margin percentage 2.70% (8.70%) 4.40% (1.80%)
Income (loss) from operations $ 2,560,289 $ (6,705,180) $ 9,122,787 $ (3,173,546)
Operating Segments | Underground Infrastructure Construction        
SEGMENT INFORMATION        
Revenue 46,269,524 32,544,499 115,446,608 85,364,645
Segment direct operating expenses (excluding depreciation) 39,322,151 34,472,373 96,249,127 79,518,142
Direct depreciation expense 2,586,777 2,299,065 5,187,271 4,141,479
Gross profit $ 4,360,596 $ (4,226,939) $ 14,010,210 $ 1,705,024
Segment gross profit percentage 9.40% (13.00%) 12.10% 2.00%
Selling, general, and administrative expenses $ 5,153,550 $ 4,780,036 $ 9,950,564 $ 9,539,485
Intangible asset amortization expenses 229,683 141,476 580,905 266,285
Segment indirect operating expenses $ 5,383,233 $ 4,921,512 $ 10,531,469 $ 9,805,770
Segment operating margin percentage (2.20%) (28.10%) 3.00% (9.50%)
Income (loss) from operations $ (1,022,637) $ (9,148,451) $ 3,478,741 $ (8,100,746)
Operating Segments | Industrial Construction        
SEGMENT INFORMATION        
Revenue 36,397,052 32,694,332 70,143,499 68,090,845
Segment direct operating expenses (excluding depreciation) 30,761,593 29,345,599 61,147,179 61,216,519
Direct depreciation expense 665,050 632,059 1,306,948 1,273,967
Gross profit $ 4,970,409 $ 2,716,674 $ 7,689,372 $ 5,600,359
Segment gross profit percentage 13.70% 8.30% 11.00% 8.20%
Selling, general, and administrative expenses $ 1,031,731 $ 980,765 $ 2,135,677 $ 1,964,158
Intangible asset amortization expenses 54,720   109,440  
Segment indirect operating expenses $ 1,086,451 $ 980,765 $ 2,245,117 $ 1,964,158
Segment operating margin percentage 10.70% 5.30% 7.80% 5.30%
Income (loss) from operations $ 3,883,958 $ 1,735,909 $ 5,444,255 $ 3,636,201
Operating Segments | Building Construction        
SEGMENT INFORMATION        
Revenue 10,506,866 11,440,320 21,695,535 23,869,775
Segment direct operating expenses (excluding depreciation) 9,605,535 9,852,195 19,168,989 20,833,716
Gross profit $ 901,331 $ 1,588,125 $ 2,526,546 $ 3,036,059
Segment gross profit percentage 8.60% 13.90% 11.60% 12.70%
Selling, general, and administrative expenses $ 1,085,811 $ 795,810 $ 2,101,481 $ 1,577,621
Indirect depreciation expense 116,552 84,953 225,274 167,439
Segment indirect operating expenses $ 1,202,363 $ 880,763 $ 2,326,755 $ 1,745,060
Segment operating margin percentage (2.90%) 6.20% 0.90% 5.40%
Income (loss) from operations $ (301,032) $ 707,362 $ 199,791 $ 1,290,999
Corporate        
SEGMENT INFORMATION        
Corporate and non-allocated costs 1,498,199 1,384,859 3,146,338 3,269,375
Corporate depreciation expense $ 3,679 $ 2,188 $ 5,273 $ 3,345