(1)

We categorize our treatment and disposal revenue as either “Base Business” or “Event Business” based on the underlying nature of the revenue source. We define Event Business as non-recurring projects that are expected to equal or exceed 1,000 tons, with Base Business defined as all other business not meeting the definition of Event Business. For the three months ended June 30, 2019 and 2018, 23% and 19%, respectively, of our treatment and disposal revenue was derived from Event Business projects. Base Business revenue accounted for 77% and 81% of our treatment and disposal revenue for the three months ended June 30, 2019 and 2018, respectively. For the six months ended June 30, 2019 and 2018, 19% and 18%, respectively, of our treatment and disposal revenue was derived from Event Business projects. Base Business revenue accounted for 81% and 82% of our treatment and disposal revenue for the six months ended June 30, 2019 and 2018, respectively.

(2)	Includes collection and transportation of non-hazardous and hazardous waste.

(3)	Includes industrial cleaning and maintenance for refineries, chemical plants, steel and automotive plants, marine terminals and refinery services such as tank cleaning and temporary storage.

(4)	Includes retail services, laboratory packing, less-than-truck-load service and household hazardous waste collection. Contracts for Small Quantity Generation may extend beyond one year and a portion of the transaction price can be fixed.

(5)

Through our TWM program, customers outsource the management of their waste compliance program to us, allowing us to organize and coordinate their waste management disposal activities and environmental compliance. TWM contracts may extend beyond one year and a portion of the transaction price can be fixed.

(6)	Includes site assessment, onsite treatment, project management and remedial action planning and execution. Contracts for Remediation may extend beyond one year and a portion of the transaction price can be fixed.

(7)	Includes spill response, waste analysis and treatment and disposal planning.

(8)	Includes equipment rental and other miscellaneous services.


	Three Months Ended June 30, 2019						Three Months Ended June 30, 2018
			Field &						Field &
	Environmental		Industrial				Environmental		Industrial
$s in thousands	Services		Services		Total		Services		Services		Total
United States	$	85,785	$	42,958	$	128,743	$	84,917	$	37,952	$	122,869
Canada		27,059		—		27,059		14,043		—		14,043
Total revenue	$	112,844	$	42,958	$	155,802	$	98,960	$	37,952	$	136,912


	Six Months Ended June 30, 2019						Six Months Ended June 30, 2018
			Field &						Field &
	Environmental		Industrial				Environmental		Industrial
$s in thousands	Services		Services		Total		Services		Services		Total
United States	$	163,144	$	81,662	$	244,806	$	159,903	$	71,540	$	231,443
Canada		42,033		—		42,033		25,528		—		25,528
Total revenue	$	205,177	$	81,662	$	286,839	$	185,431	$	71,540	$	256,971