(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 March 31, 2020 and 2019, 25% and 15%, respectively, of our treatment and disposal revenue was derived from Event Business projects. Base Business revenue accounted for 75% and 85% of our treatment and disposal revenue for the three months ended March 31, 2020 and 2019, 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 total waste management (“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)

We provide government-mandated, commercial standby oil spill compliance solutions to companies that store, transport, produce or handle petroleum and certain nonpetroleum oils on or near U.S. waters. Our standby services customers pay annual retainer fees under long-term or evergreen contracts for access to our regulatory certifications, specialized assets and highly trained personnel. When a customer with a retainer contract experiences a spill incident, we coordinate and manage the spill response, which results in incremental revenue for the services provided, in addition to the retainer fees.

(9)	Includes equipment rental and other miscellaneous services.


	Three Months Ended March 31, 2020						Three Months Ended March 31, 2019
			Field &						Field &
	Environmental		Industrial				Environmental		Industrial
$s in thousands	Services		Services		Total		Services		Services		Total
United States	$	107,928	$	105,546	$	213,474	$	77,359	$	38,705	$	116,064
Canada		18,817		1,077		19,894		14,973		—		14,973
EMEA		—		5,239		5,239		—		—		—
Other (1)		—		2,113		2,113		—		—		—
Total revenue	$	126,745	$	113,975	$	240,720	$	92,332	$	38,705	$	131,037