OPERATING SEGMENTS (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 segment	Sep. 30, 2012	Dec. 31, 2012
OPERATING SEGMENTS
Number of reportable segments			2
OPERATING SEGMENTS
Revenue	$ 53,090,000	$ 45,739,000	$ 141,766,000	$ 118,732,000
Direct operating costs	20,902,000	19,893,000	61,745,000	56,164,000
Transportation costs	10,568,000	7,257,000	24,091,000	14,577,000
Gross profit	21,620,000	18,589,000	55,930,000	47,991,000
Selling, general & administrative expense	6,108,000	6,196,000	18,353,000	18,167,000
Operating income	15,512,000	12,393,000	37,577,000	29,824,000
Interest income (expense), net	(204,000)	(227,000)	(640,000)	(646,000)
Foreign currency gain (loss)	683,000	1,605,000	(1,448,000)	1,775,000
Other income	77,000	70,000	268,000	672,000
Income before income taxes	16,068,000	13,841,000	35,757,000	31,625,000
Income tax expense	5,740,000	5,179,000	12,813,000	12,078,000
Net income	10,328,000	8,662,000	22,944,000	19,547,000
Depreciation, amortization & accretion	4,397,000	4,148,000	12,811,000	12,336,000
Capital expenditures	3,060,000	6,690,000	15,590,000	12,433,000
Total assets	230,731,000	223,730,000	230,731,000	223,730,000	218,694,000
Treatment and disposal
OPERATING SEGMENTS
Revenue	42,495,000	38,583,000	117,569,000	104,502,000
Transportation services
OPERATING SEGMENTS
Revenue	10,595,000	7,156,000	24,197,000	14,230,000
Operating Disposal Facilities
OPERATING SEGMENTS
Revenue	53,084,000	45,734,000	141,750,000	118,716,000
Direct operating costs	20,847,000	19,838,000	61,583,000	55,997,000
Transportation costs	10,568,000	7,257,000	24,091,000	14,576,000
Gross profit	21,669,000	18,639,000	56,076,000	48,143,000
Selling, general & administrative expense	2,611,000	2,868,000	8,524,000	8,310,000
Operating income	19,058,000	15,771,000	47,552,000	39,833,000
Interest income (expense), net	4,000	4,000	10,000	13,000
Foreign currency gain (loss)	(233,000)	(165,000)	199,000	(247,000)
Other income	75,000	68,000	261,000	669,000
Income before income taxes	18,904,000	15,678,000	48,022,000	40,268,000
Net income	18,904,000	15,678,000	48,022,000	40,268,000
Depreciation, amortization & accretion	4,336,000	4,083,000	12,628,000	12,142,000
Capital expenditures	2,915,000	6,690,000	15,330,000	12,400,000
Total assets	222,503,000	215,786,000	222,503,000	215,786,000
Operating Disposal Facilities | Treatment and disposal
OPERATING SEGMENTS
Revenue	42,489,000	38,578,000	117,553,000	104,486,000
Operating Disposal Facilities | Transportation services
OPERATING SEGMENTS
Revenue	10,595,000	7,156,000	24,197,000	14,230,000
Non-Operating Disposal Facilities
OPERATING SEGMENTS
Revenue	6,000	5,000	16,000	16,000
Direct operating costs	55,000	55,000	162,000	167,000
Transportation costs				1,000
Gross profit	(49,000)	(50,000)	(146,000)	(152,000)
Operating income	(49,000)	(50,000)	(146,000)	(152,000)
Other income	2,000	2,000	7,000	3,000
Income before income taxes	(47,000)	(48,000)	(139,000)	(149,000)
Net income	(47,000)	(48,000)	(139,000)	(149,000)
Depreciation, amortization & accretion	52,000	54,000	156,000	162,000
Capital expenditures				17,000
Total assets	87,000	97,000	87,000	97,000
Non-Operating Disposal Facilities | Treatment and disposal
OPERATING SEGMENTS
Revenue	6,000	5,000	16,000	16,000
Corporate
OPERATING SEGMENTS
Selling, general & administrative expense	3,497,000	3,328,000	9,829,000	9,857,000
Operating income	(3,497,000)	(3,328,000)	(9,829,000)	(9,857,000)
Interest income (expense), net	(208,000)	(231,000)	(650,000)	(659,000)
Foreign currency gain (loss)	916,000	1,770,000	(1,647,000)	2,022,000
Income before income taxes	(2,789,000)	(1,789,000)	(12,126,000)	(8,494,000)
Income tax expense	5,740,000	5,179,000	12,813,000	12,078,000
Net income	(8,529,000)	(6,968,000)	(24,939,000)	(20,572,000)
Depreciation, amortization & accretion	9,000	11,000	27,000	32,000
Capital expenditures	145,000		260,000	16,000
Total assets	$ 8,141,000	$ 7,847,000	$ 8,141,000	$ 7,847,000