Disposal Site Postclosure Land Use

To All Local Enforcement Agencies:

The purpose of this advisory is to provide guidance and information to the Solid Waste Local Enforcement Agencies (LEA) on oversight of disposal site postclosure land use pursuant to Title 27, California Code of Regulations (27 CCR), section 21190. Specific topics addressed include regulatory authority, activities subject to the regulatory tiers, site boundary issues, proposal review, local approvals, technical assistance, and site inspections.


Control of postclosure land use at solid waste disposal sites represents a major part of the LEA’s responsibility to protect public health and safety and the environment. The California Integrated Waste Management Board (CIWMB) established regulations addressing postclosure land use activities in 1989 based on documented problems associated with poorly regulated development on disposal sites (Final Statement of Reasons, Disposal Site Standards for Closure and Postclosure, Page III-7.8 129-139). In many cases, the CIWMB and LEA are still dealing with the consequences of poor past postclosure land use practices.

Although there are many examples of poor postclosure land use practices, significant recent advances in the land use development and environmental control of disposal sites are evident. There are an increasing number of projects that have been successfully constructed and maintained in compliance with current minimum standards. Attachment 1 is a list of selected examples of postclosure land use projects developed in accordance with current minimum standards. Upon request, more specific information concerning these and other projects can be provided by staff of the CIWMB’s Remediation, Closure, and Technical Services Branch.

Postclosure land use development can be a substantial benefit to local communities. Attractive and useful postclosure land uses can help incorporate a closed site into the surrounding community. Postclosure land use development can also provide a potential source of financial resources to remediate environmental problems at sites where the responsible parties are unable to finance remediation on their own.

Regulatory Authority Over Postclosure Land Use Activities

The specific minimum standard for postclosure land use at disposal sites is contained in 27 CCR 21190 (attachment 2). This standard is applicable to new postclosure activities that may jeopardize the integrity of previously closed disposal sites or pose a potential threat to public health and safety or the environment (27 CCR 21100(b)(2)).

CIWMB closure and postclosure maintenance plan requirements apply to all solid waste landfills required to be permitted that were operating on or after January 1, 1988. Closure and postclosure maintenance plans under these requirements require a description of proposed postclosure land use per 27 CCR 21190. If the postclosure land use is proposed to significantly change after approval of the final closure and postclosure maintenance plans (final plans), revision of the final plans is required pursuant to 27 CCR 21890. The revision for significant postclosure land use change must specifically address compliance with 27 CCR 21190 and be approved by the LEA, Regional Water Quality Control Board (RWQCB), and CIWMB.

CIWMB closure and postclosure maintenance plan requirements of 27 CCR Chapter 4, Subchapter 4 are not applicable for sites that ceased operating prior to January 1, 1988 (27 CCR 21770(b)). If a significant change in postclosure land use is proposed for these sites, a postclosure land use proposal should be submitted to the LEA to address compliance with 27 CCR 21190. The LEA is required to approve the proposed postclosure land use if the project involves structures within 1,000 feet of the disposal area, structures on top of waste, modification of the low permeability layer, or irrigation over waste (27 CCR 21190(c)).

Many disposal sites have pre-existing postclosure land use activities (in place prior to August 18, 1989). Review and approval of these land use activities under 27 CCR 21190 is not required. However, LEAs should note that there is significant flexibility in applying minimum standards for closure and postclosure to pre-existing land use activities. This flexibility is contained in 27 CCR 21100(d), which gives the LEA authority to apply any closure or postclosure standard to these sites as necessary to address a threat to public health and safety or the environment. Similar flexibility is contained in 27 CCR 21100(f) which applies to non-municipal solid waste landfill (MSWLF) units (e.g., wood waste landfills).

Activities Subject to the Regulatory Tiers

Public Resources Code (PRC) Sections 44001 and 44002 require operators of solid waste facilities to obtain solid waste facility permits. Therefore, activities subject to the regulatory tiers, located within the boundaries of closed or closing disposal sites (e.g., composting facilities), must obtain the applicable solid waste permit before these activities can commence unless specifically exempted or excluded. These activities are also subject to the postclosure land use standards of 27 CCR 21190. Activities subject to tiered permits must either be already incorporated into the approved final plans, or be added as revisions to the approved final plans for closed or closing sites operating on or after January 1, 1988. For sites that ceased operating prior to January 1, 1988, final plans are not required and the proposed activities would be submitted as a proposal pursuant to 27 CCR 21190.

If an activity changes beyond the approved land use change (e.g., new or expanded layout, higher waste throughput, new permit tier activity) a new postclosure land use proposal or revision to the final plans should be submitted.

Site Boundary Issues

“Disposal site” or “site” includes the place, location, tract of land, area, or premises in use, intended to be used, or which has been used for the landfill disposal of solid wastes (PRC Section 40122). In practice, this definition means that any property located outside the parcel containing the solid waste is not subject to the postclosure land use requirements of 27 CCR 21190, even if the outside property is within 1,000 feet of the waste footprint (27 CCR 21190(c)). This can be problematic for the CIWMB and LEA because parcel boundaries can be split from the disposal site, allowing development close to the waste footprint without triggering postclosure land use controls and approvals.

Local building codes and ordinances can provide enforceable buffer zones controlling land use development adjacent to disposal sites (e.g., Los Angeles County building codes). Another way for the LEA to influence the control of postclosure land use development adjacent to disposal site parcels is to participate as early as possible in the local planning process when rezoning and building permits come up for issuance. It is also important to note that where the Department of Toxic Substances Control (DTSC) has jurisdiction over postclosure land use pursuant to California Health and Safety Code Section 25221 (i.e., hazardous waste sites), it has broad authority over adjacent land use activities on property outside the disposal area.

Review of Postclosure Land Use Proposals

Suggested guidelines for review of all postclosure land use proposals, revisions to final plans, or portions of closure and postclosure maintenance plans, subject to 27 CCR 21190, are as follows:

1. Project Description (27 CCR 21190(a-c))

Check description of postclosure land use activity and implementation schedule. Is the detail sufficient to address 27 CCR 21190(a-c)? Review description of land use change to ensure consistency with any required tier permit application and permit covering the activity.

Check if the project involves waste excavation and relocation and/or consolidation. If yes, a thorough description of this activity should be provided including project health and safety measures and waste characterization, handling, processing, and placement. This activity may also fall under DTSC jurisdiction if the waste is hazardous (e.g., burn dump ash with residue exceeding hazardous levels for metals). Guidance for complete removal of waste and waste residuals (“clean closure”) is contained in LEA Advisory No. 16. For the specific case of burn dump remediation, a separate LEA Advisory will be issued.


Does the proposal include verification of compliance with the California Environmental Quality Act (CEQA) (e.g., Notice of Determination)? CEQA is required for the discretionary approval of a project by the LEA, which would include most postclosure land use changes. In most cases the local planning department is lead agency for ensuring compliance with CEQA requirements for these projects. If so, the LEA is a responsible agency and should coordinate with the lead agency early in the process.

3. Project Layout (27 CCR 21190(a-c))

Check site maps and grading plans to ensure that the specific limits of the land use change are clearly delineated with respect to the closed disposal site and all existing environmental monitoring and control systems. Check specifically for delineation of areas on waste that will be irrigated or capped by relatively impermeable materials such as asphalt concrete. These activities can result in increased landfill gas generation and migration. Environmental monitoring and control systems to be evaluated include site security, erosion control, drainage, leachate collection and removal, and landfill gas monitoring and control. Research site files to determine if there are documented problems with landfill gas, leachate, or drainage that must be specifically addressed in the project.

All construction plans should be signed and stamped by an appropriately licensed professional such as a person registered as a civil engineer in the State of California [27 CCR 21780(a)].

4. Environmental Monitoring and Control Systems (27 CCR 21190(a),(d))

Check facility layout with respect to existing environmental monitoring and control systems. Is the land use change compatible with the existing environmental monitoring and control systems? Will these systems need to be expanded, decommissioned, or reconstructed? If so, the proposal should include revised design plans, specifications, construction schedule, and revisions to the postclosure monitoring and maintenance plan. If required, it is important that on-site maintenance personnel implement monitoring and operations plans for landfill gas, in addition to ensuring that methane alarm systems are maintained.

5. Structures (27 CCR 21190(c-g))

Does the proposal include enclosed structures on waste or within 1,000 feet of the waste footprint within the property boundary? If yes, approval by the LEA is required (27 CCR 21190(c)). If yes, check to see if construction design standards of 27 CCR 21190(e) and (g) are met in plans and specifications (flexible utility connections, floor slab barrier, vent layer, vent piping, automatic methane sensors with alarm system, periodic methane monitoring program of structure). Check for evaluation of slope stability to ensure the integrity of landfill slopes under both static and dynamic conditions (27 CCR 21145).

Check that a construction quality assurance (CQA) plan has been submitted. A CQA plan should be included to ensure that construction is completed in accordance with plans and specifications. The CQA plan should also include submittal and certification of as-built plans and specifications upon completion of construction.

Equivalent alternative designs can be proposed but must be supported for the intended function. For example, it is very important that any alternative proposed to the standard geomembrane barrier layer have documentation (e.g., manufacturer specifications) showing equivalent low permeability to landfill gas. In addition, exemptions are allowed from the construction standards if the applicant demonstrates on a site-specific basis that there is no potential for adverse impacts on public health and safety and the environment from landfill gas migration into structures.

6. Pilings (27 CCR 21190(e)(6-7))

Construction of deep foundations with pilings in waste is a special case normally requiring a licensed geotechnical engineer. Detailed plans and specifications are necessary to ensure that penetrations of final cover are adequately sealed and that appropriate corrosion resistance is provided. Check to ensure depth of piles does not penetrate any bottom liner unless approved by the RWQCB.

7. Modification or Replacement of Low Permeability Layer (27 CCR 21190(d))

Is the site required to have a low permeability layer in the final cover? For sites that ceased accepting waste prior to January 1, 1988, this determination is frequently made by the RWQCB, but the LEA has authority to require a low permeability layer if necessary to protect public health and safety and the environment (e.g., landfill gas control). If a low permeability layer is required, does the proposal include modification or replacement of the low permeability layer of the final cover? If so, approval by the LEA and RWQCB is required (27 CCR 21190(d)), and grading plans, specifications, and CQA plans should also be included.

8. Land Use on Final Cover (27 CCR 21190(a-c))

Is the postclosure land use change within areas underlain by final cover or waste? If so, the land use should be evaluated with respect to potential settlement and damage to the final cover. The evaluation should include an estimation of the potential settlement as a result of the activity and whether or not the settlement is tolerable for the integrity of the final cover and the activity proposed. If there is the potential for significant settlement the methods for monitoring and repair should be included.

Is the addition of a soil cover needed to protect public health and safety (e.g., to prevent public contact with waste)? If so, plans and specifications for the additional cover should be included.

Local (City, County, or Regional) Project Approvals

Reviewers of postclosure land use proposals should also note that separate local permits or approvals (e.g., building, grading, conditional use, air district) may be required for the project depending on local codes and ordinances. Conflicts can arise due to the overlapping reviews and approvals of these agencies. Therefore, LEAs should contact the other applicable local agencies as early in the development of the postclosure land use project as possible to help coordinate the reviews and approvals.

Technical Assistance

Staff from the CIWMB Remediation, Closure, and Technical Services Branch is available to LEAs, other agencies, and project applicants for technical assistance on disposal site postclosure land use. Licensed engineers from the branch are also available to the LEA if requested to assist in the review and approval of postclosure construction projects.

Site Inspections

A major aspect of disposal site inspections for postclosure land use is to ensure that there is no change or expansion in land use activities without prior comment or approval as required. For example, LEAs have been faced with unauthorized construction activities on disposal sites where a significant landfill gas hazard is suspected, and no control systems have been planned. This situation would constitute a violation of 27 CCR 21190 and would warrant prompt enforcement action by the LEA to address the problem. LEAs should also inspect approved projects under construction to ensure that the approved plans and specifications are being addressed.

If the LEA observes a potential threat to public health and safety or the environment at a site with an existing or approved new postclosure land use activity a violation or area of concern should be issued. Examples of such observations would include, but not be limited to:

  • Exposure of the public to waste.
  • Excessive differential settlement in areas over waste (damage to buildings, utilities, parking lots, and roads; ponding on waste; surface cracking with the potential for release of gas into structures).
  • Detection of landfill gas within structures or appurtenant utilities exceeding 1.25 % methane by volume in air.
  • Non-operational methane alarm systems.
  • Failure to monitor and control landfill gas as required.

A violation or area of concern should be issued based on the inspector’s determination of threat to public health and safety or the environment. Detection of methane greater than 1.25 % in enclosed structures should be cited as a violation of 27 CCR 21190, 20919, and for municipal solid waste landfills, 27 CCR 20919.5.

The owner’s promptness in correcting violations would bear on what level of enforcement action is appropriate. LEA staff should contact their Remediation, Closure, and Technical Services Branch staff liaison if specific examples of enforcement orders on closed sites are desired, or if assistance in site inspections is desired.

Tracking of Postclosure Land Use Changes

To control potential postclosure land use changes and justify a reduction in inspection frequencies a tracking system is recommended. Such a tracking system would typically involve a computer database system by which other local approval agencies (e.g., planning, building departments) flag parcels for referral to LEAs when a permit or approval is requested. This would allow the LEA to be involved early in the development process so that later conflicts are avoided. In some cases deed restrictions on disposal site properties have been applied, although that process would normally require the involvement of county counsel and would need to occur before property is conveyed to another party.

Further questions or technical assistance concerning postclosure land use and the topics discussed may be directed to Remediation, Closure, and Technical Services Branch liaisons.


Original signed by:

Deputy Director
Permitting and Enforcement Division

Attachment 1: Examples of Disposal Site Postclosure Land Projects

Attachment 2: Disposal Site Postclosure Land Use Regulation

Publication #231-98-011

The intent of the advisories is to provide guidance to Local Enforcement Agencies (LEA) in performing their duties. Guidance, for this purpose, is defined as providing explanation of the Board’s regulations and statutes.

Unless included by reference in the LEA’s Enforcement Program Plan (EPP), advisories are not enforceable in the same manner as regulations because they have not been adopted through the formal rulemaking process (see Government Code sections 11340.5 and 11342.6). Advisories do not take precedence over statute or regulation.

Please note: These LEA advisories are retained for historical purposes. Over time, some information and links on these pages may become dated and/or inaccurate.