Operating Segments - Financial Information for Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 31, 2013	Oct. 31, 2012	Oct. 31, 2013	Oct. 31, 2012
Segment Reporting Information [Line Items]
Revenues	$ 216,462	$ 281,281	$ 674,923	$ 841,018
(Loss) income from continuing operations before income taxes	(19,481)	7,455	(67,501)	15,950
Equity in (losses) earnings of affiliates	(2,300)	4,947	(4,088)	19,069
Interest expense	(2,038)	(1,604)	(4,908)	(3,020)
Operating Segments [Member] | Water Resources [Member]
Segment Reporting Information [Line Items]
Revenues	46,807	55,135	135,876	164,677
(Loss) income from continuing operations before income taxes	583	2,702	2,193	5,393
Operating Segments [Member] | Inliner [Member]
Segment Reporting Information [Line Items]
Revenues	43,806	32,115	111,971	101,682
(Loss) income from continuing operations before income taxes	5,717	2,791	12,025	7,927
Operating Segments [Member] | Heavy Civil [Member]
Segment Reporting Information [Line Items]
Revenues	63,820	70,472	213,431	219,723
(Loss) income from continuing operations before income taxes	352	(5,487)	(1,190)	(21,632)
Operating Segments [Member] | Geoconstruction [Member]
Segment Reporting Information [Line Items]
Revenues	20,087	44,816	62,966	104,208
(Loss) income from continuing operations before income taxes	(2,873)	5,233	(28,771)	4,617
Equity in (losses) earnings of affiliates				3,488
Operating Segments [Member] | Mineral Services [Member]
Segment Reporting Information [Line Items]
Revenues	39,773	76,498	144,326	243,965
(Loss) income from continuing operations before income taxes	(9,666)	11,231	(7,484)	48,087
Equity in (losses) earnings of affiliates	(2,300)	4,947	(4,088)	15,581
Operating Segments [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues	1,727	1,256	5,268	4,435
(Loss) income from continuing operations before income taxes	(1,167)	(1,094)	(2,656)	(2,367)
Operating Segments [Member] | Other [Member]
Segment Reporting Information [Line Items]
Revenues	5,481	3,087	15,241	7,635
(Loss) income from continuing operations before income taxes	(57)	477	285	426
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	(5,039)	(2,098)	(14,156)	(5,307)
Unallocated corporate expenses [Member]
Segment Reporting Information [Line Items]
(Loss) income from continuing operations before income taxes	(10,332)	(6,794)	(36,995)	(23,481)
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Interest expense	$ (2,038)	$ (1,604)	$ (4,908)	$ (3,020)