Colorado Department of Public Health and Environment 

Hazardous Materials and Waste Management Division Policies 

Policy Title: End of Post-Closure Care 

Program(s) Initiating the Policy: Solid & Hazardous Waste Program 

Program(s) Subject to the Policy: Solid & Hazardous Waste Program 

Statutory and Regulatory Citations: 6 CCR 1007-3, §264.117(a) and §265.117(a) 

Policy Purpose: 

Since the inception of the federal Resource Conservation and Recovery Act (RCRA) and its state 

equivalent, the Colorado Hazardous Waste Act (CHWA), one focus of the regulatory program 

has been to require facilities that treat, store or dispose of hazardous waste to either obtain a 

permit to continue operating or to close their regulated units. Closures that result in leaving 

waste and/or contamination behind, thereby creating a landfill, require the facility to perform 

long-term post-closure care of the hazardous waste management unit. The purpose of this policy 

is to define the criteria by which the Department will determine that the regulatory requirements 

for closure have been satisfied and post-closure care of the regulated unit may cease. 

Policy:

6 CCR 1007-3, §264.111 and §265.111 of the Colorado Hazardous Waste Regulations establish 

performance standards for regulated units at closing facilities, consisting primarily of activities 

that a) minimize the need for further maintenance and controls, and b) minimize or eliminate 

future releases of hazardous waste and constituents to the degree necessary to protect human 

health and the environment. Although a facility may have successfully achieved these standards, 

the fact that not all hazardous waste and constituents have been removed from the facility 

triggers the need for long-term maintenance and monitoring of the hazardous waste management 

unit during the post-closure care period. 6 CCR 1007-3, §264.117(a) and §265.117(a) state 

“Post-closure care for each hazardous waste management unit...must begin after completion of 

closure of the unit and continue for 30 years after that date.” These sections go on to state that 

the Department may at any time during the post-closure care period either shorten or lengthen 

the post-closure care period applicable to the hazardous waste management unit and the wastes 

managed therein. 

Accordingly, the Department may decide that post-closure care is no longer required at a 

hazardous waste management unit if human health and the environment are sufficiently 

protected. Although these sections do not require evaluation of specific criteria, they do suggest 

factors that may be considered in making the decision to shorten or end the post-closure care 

period. These factors include environmental monitoring results, characteristics of the waste and 
characteristics of the unit that might suggest the facility is secure, stable and predictable in its 

present and anticipated future state. 

CDPHE Criteria for Ending Post-Closure Care and Maintenance

Post-closure care under the CHWA may end at regulated units when one of the following 

conditions is satisfied: 

1) The regulated unit is clean closed, either by removing the waste and any associated 

contamination, or by delisting the waste, rendering it non-hazardous for management as a solid 

waste either within the existing unit or at some other solid waste facility; or 

2) The Department approves, in accordance with 6 CCR 1007-3, §264.117(a)(i) or 

§265.117(a)(i), a proposal to end post-closure care after completing a performance-based 

evaluation that considers all relevant unit design and environmental factors to determine that the 

hazardous waste unit is secure and protective of human health and the environment. The data 

and site information to be evaluated include, but are not limited to: 

• Leachate monitoring results (quality and quantity) 

• Ground water monitoring results 

• Characteristics of the hazardous waste 

• Hydrogeologic characteristics of the formation beneath and around the unit 

• Overall design of the unit to minimize long-term maintenance, resist the generation of 

leachate and contain the waste in perpetuity 

• The potential for waste or constituents to migrate from the regulated unit 

• Management and maintenance history of the unit (including cap and liner) 

• End-use strategy and the enforceable mechanism ensuring the continued use and care of 

the property 

The Department will review the information provided, and will consider releasing the unit from 

long-term post-closure care only if the following conditions are met: 

• The waste in the regulated unit is and will continue to be stable; 

• There have been no releases from the unit in the past, or if a release did occur, corrective 

measures were implemented successfully and subsequent monitoring shows no evidence 

of a reoccurrence; 

• The unit configuration/design ensures that a release or exposure to the waste is unlikely 

or nonexistent; 

• Little or no maintenance is required to prevent the migration of or exposure to the waste; 

• The institutional controls in the environmental covenant would ensure the preceding 

conditions would continue in perpetuity; 

• Even if a release were to occur from the unit in the future, the anticipated impact to 

human health and the environment would be minimal and may not justify an active 

response.