Property, Plant and Equipment

12 Months Ended

Sep. 30, 2023

Property, Plant and Equipment [Abstract]

Property, plant and equipment at September 30, 2023 and 2022 consisted of the following (in thousands):


	September 30,
	2023		2022
Construction equipment	$	447,467	$	402,581
Plants	208,708		167,625
Land and improvements	76,396		59,454
Mineral reserves	69,405		91,992
Buildings	36,885		32,566
Furniture and fixtures	7,538		7,110
Leasehold improvements	1,268		1,230
Total property, plant and equipment, gross	847,667		762,558
Accumulated depreciation, depletion and amortization	(358,462)		(304,935)
Construction in progress	15,890		23,789
Total property, plant and equipment, net	$	505,095	$	481,412

Depreciation, depletion and amortization expense related to property, plant and equipment for the fiscal years ended September 30, 2023, 2022 and 2021 was $80.0 million, $68.9 million and $49.5 million, respectively.

Mineral reserves, net of accumulated depletion, for the years ended September 30, 2023 and 2022 were $63.6 million and $87.6 million, respectively. These amounts include $1.5 million and $2.0 million of asset retirement obligation assets, net of accumulated depletion associated with active mining operations for the years ended September 30, 2023 and 2022, respectively, and $0.8 million and $3.9 million of capitalized stripping costs, net of accumulated depletion associated with development stage mining operations for the fiscal years ended September 30, 2023 and 2022, respectively.