LEA Advisory #54—October 26, 1998

Inspection Guidance for Landfills—Part 10

A disposal site other than a MSWLF unit, may be granted an exemption to all or any portion of the requirements of Article 6 of this Subchapter if the operator can demonstrate to the satisfaction of the of the EA, that there is no potential for adverse impacts on the public health and safety and the environment, based upon but not limited to: the amount, nature and age of refuse; projected gas generation; and remoteness of the facility. Exemptions and alternatives shall be reviewed by the EA in conjunction with the five (5) year permit review, and based on the results, the EA may extend or terminate the exemption.

This standard applies only to active non-MSWLF units. This standard requires that the operator make this demonstration only to the EA for evaluation of exemption status from this standard.

Where the Enforcement Agency, the local fire control authority, or the CIWMB has cause to believe a hazard or nuisance may be created by landfill decomposition gases, they shall so notify the owner. Thereafter, the site owner shall cause the site to be monitored for presence and movement of gases, and shall take necessary action to control such gases. The site owner shall inform the operator of any actions ordered by the EA, the local fire control authority or the CIWMB concerning gas control methods. The monitoring program shall be developed pursuant to the specifications of the above agencies. The monitoring program shall not be discontinued until authorized to do so in writing by the requiring agency. Results of the monitoring shall be submitted to the appropriate agencies. If monitoring indicates methane gas movement away from the site, the owner shall, within a period of time specified by the requiring agency, construct a gas control system approved by that agency. The agency may waive this requirement if satisfactory evidence is presented indicating that adjacent properties are safe from hazard or nuisance caused by methane gas movement. The operator shall duly inform the disposal site owner of possible landfill gas problems.

Since 27 CCR §20919.5 requires gas monitoring and control only at MSWLFs this standard on Gas Control may be applied to non-MSWLFs. If the inspector believes that there is a gas problem at a landfill that falls under this standard, those requirements outlined in 27 CCR §20919.5 may be used as a guideline for gas monitoring and control.

(a) Owners or operators of all MSWLF units must ensure that::

(1) The concentration of methane gas generated by the facility does not exceed 25 percent of the lower explosive limit for methane in facility structures (excluding gas control or recovery system components); and

(2) The concentration of methane gas does not exceed the lower explosive limit for methane at the facility property boundary.

(b) Owners or operators of all MSWLF units must implement a routine methane-monitoring program to ensure that the standards of paragraph (a) are met.

(1) The type and frequency of monitoring must be determined based on the following factors:

(i) soil conditions;

(ii) the hydrogeologic conditions surrounding the facility;

(iii) the hydraulic conditions surrounding the facility; and

(iv) the location of facility structures and property boundaries.

(2) The minimum frequency of monitoring shall be quarterly.

(c) If methane gas levels exceeding the limits specified in paragraph (a) of this section are detected, the owner or operator must:

(1) Immediately take all necessary steps to ensure protection of human health and notify the EA;

(2) Within seven days of detection, place in the operating record the methane gas levels detected and a description of the steps taken to protect human health; and

(3) Within 60 days of detection, implement a remediation plan for the methane gas releases, place a copy of the plan in the operating record, and notify the EA that the plan has been implemented. The plan shall describe the nature and extent of the problem and the proposed remedy.

(4) The EA with concurrence by the CIWMB pursuant to 40 CFR 258.23 (c) (4) may establish alternative schedules for demonstrating compliance with paragraphs (c)(2) and (3) of this section.

(d) For purposes of this section, "lower explosive limit" means the lowest percent by volume of a mixture of explosive gases in air that will propagate a flame at 25 degrees Celsius and atmospheric pressure.

(e) The EA shall forward notifications and approvals pursuant to 20919.5(c)(1) and (c)(3) to the CIWMB pursuant to 40 CFR 258.23(c)(1) and (c)(3).

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Actions required to be taken by the operator are stated in the regulation. The methane gas monitoring program should be approved by the EA. CIWMB staff may be contacted for assistance in reviewing the program. The EA should evaluate this standard at active solid waste landfills by (1) using a CGI to measure methane levels in appropriate gas probes and barholes on a monthly basis, or (2) overseeing the operator's quarterly monitoring by observing the monitoring, verifying a representative portion of the operator's findings with LEA gas monitoring instrumentation, and documenting the date of the monitoring and any findings on a SWIS inspection report to the CIWMB Permitting and Inspection Branch contact. Actions taken at MSWLFs to mitigate gas problems include installation of landfill gas monitoring systems approved by the LEA and/or the CIWMB, installation of landfill gas control systems, installation of structural gas control systems, sealing floor cracks of on-site structures, improving ventilation, removal of the structure(s), and purchasing contiguous property as a buffer zone.

Landfill gas may contain potentially harmful trace constituents. See Appendix M for a listing of prevalent trace gases from Class III MSWLFs. Chronic exposure to these constituents may result in health problems.

The lower explosive limit (LEL) of a combustible gas is the lowest concentration of that gas by volume in air that will explode, ignite, or burn when there is an ignition source. For methane the LEL is 5 percent. The upper explosive limit (UEL) is the highest concentration of gas that will explode, ignite, or burn with an ignition source present. For methane the UEL is 15 percent. Below the LEL there is insufficient fuel to support explosion. Above the UEL there is insufficient oxygen to support explosion. However, care should be taken as a small dilution with air can bring the level back to an explosive concentration.

A violation should be noted if any of the following are found during the inspection:

1) Concentrations of methane exceed 5 percent or greater by volume in air at the facility property boundary, or 1.25 percent or greater by volume in air in on-site structures, including underground chambers.

Note: "Facility property boundary" means the boundary designated in the SWFP for the site and does not apply to all the land owned by the operator that may be adjacent to the permitted boundary of the facility. The 5 percent methane level requirement at the "facility property boundary" does not apply to unpermitted disposal sites. However, §17705–Gas Control can be applied at unpermitted sites for methane gas levels above the LEL.

2) A routine methane-monitoring program is not implemented with a minimum of quarterly frequency.

3) The operator has not taken the required measures when methane exceeds the limits specified above.

4) The operator has not complied with the alternative schedule requirement of this standard.

An area of concern should be noted if the combustible gas concentration in an on-site structure is between 100 ppm and 12,500 ppm (1.25 percent or 25 percent of the LEL).

Note: Gas monitoring results and any remediation plans must be placed in the operating record §20515–Recordkeeping Requirements.

The inspector should make the above determinations with appropriate instrumentation. Monitoring at the property boundary should be done initially using either a bar hole punch, existing property boundary landfill gas monitoring probes, or a combination of the two. When a gas migration problem is suspected at the site boundary where no landfill gas monitoring probes have been installed, and despite readings below 5 percent by volume in air in bar holes, the EA should measure methane levels at greater depths. The LEA may request that CIWMB staff use its gas vapor probe equipment to measure combustible gas concentrations to a depth of 20 feet or more, depending on site geology. The EA should follow up on violations of this section, and require the operator to take adequate steps to monitor and control gas. For purposes of this standard "at" means as close to the property boundary as possible, but within several feet. The LEA may request CIWMB assistance with technical review of landfill gas control plans.

If an air quality problem is observed or suspected, the inspector should communicate all concerns to the appropriate AQMD or APCD. Problems include excessive landfill gas emissions, odors, dust, or emissions from landfill gas destruction equipment. In cases where the AQMD has a corrective action order, the AQMD coordinates with the EA in the design of the system.

Please refer to LEA Advisory #44 for comprehensive information on gas monitoring procedures.

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Closure

LEAs are also encouraged to contact their Remediation, Closure and Technical Services Branch staff person for assistance in inspecting closed sites, or those in the process of closing, pursuant to the closure requirements of 27 CCR, Subdivision 1, Chapter 3, Subchapter 5, Article 2. A separate LEA advisory for closure site inspections will be provided in the future.

27 CCR §21780 Submittal of Closure Plans

(a) Each submittal shall be certified by a registered civil engineer or a certified engineering geologist. Each submittal shall include:

(1) The preliminary or final closure and postclosure maintenance plans containing all of the elements specified under §21790 through §21840 as applicable.

(2) Updated cost estimates for closure and postclosure activities to reflect the components under §21820 and §21840.

(3) An updated demonstration of financial responsibility in accordance with Subchapter 2 of Chapter 6 (§22205 et seq.). This demonstration shall reflect the updated cost estimates for closure and postclosure activities required under ¶(a)(2).

(b) The operator shall submit two copies of each document to the EA, the RWQCB and the local air district. All drawings shall be submitted at an appropriate scale that clearly shows all pertinent features. The closure and postclosure maintenance plans shall be clearly marked "preliminary" or "final", depending on the status. For partial final closure, those sections submitted pursuant to §21800, shall be clearly marked "partial final."

(c) Plans for complete site closure of a solid waste landfill shall be submitted in accordance with the following schedule:

(1) Preliminary closure and postclosure maintenance plans for existing solid waste landfills shall be submitted as part of the JTD or as a separate document at the time of application for each SWFP review or revision;

(2) preliminary closure and postclosure maintenance plans for new landfills not operating prior to the effective date of the regulations shall be submitted as part of the JTD at the time of application for a SWFP. For the purposes of this subchapter, lateral expansions of landfills are considered new municipal solid waste landfills.

(3) final closure and postclosure maintenance plans for solid waste landfills shall be submitted two years prior to the anticipated date of closure. Within five years of the anticipated date of closure, the operator may submit the final closure and postclosure maintenance plans in lieu of submitting new or updated preliminary closure and postclosure maintenance plans.

(d) Partial final closure of a solid waste landfill shall be allowed in accordance with the following:

(1) for the complete closure of discrete units, partial final closure and postclosure maintenance plans shall be submitted for each unit 2 years prior to the anticipated date of closure of that discrete unit in accordance with §21800 and §21830. Closure of such a discrete unit shall not commence until approval of the partial final closure and postclosure maintenance plans for that discrete unit. The specific closure details for each discrete unit shall be compatible with closure of the entire landfill; and

(2) for the implementation of any one or a combination of individual final closure activities, partial final closure and postclosure maintenance plans for the activities shall be approved before implementation of such closure activities.

(e) If immediate closure of a disposal site is necessary to protect public health and safety and the environment, closure plans shall be submitted in accordance with a schedule specified by the EA. An emergency corrective action plan may be required by the EA, to be submitted for approval by the EA. The emergency corrective action plan may be implemented prior to the submittal of the closure plan.

(f) The owner or operator of a MSWLF unit shall notify the EA that closure and postclosure maintenance plans have been prepared and placed in the operating record in accordance with 40 CFR 258.60(d) and 258.61(d)

For additional guidance on submittal of closure and postclosure maintenance plans LEAs should communicate with their Remediation, Closure and Technical Services Branch staff contact. A separate LEA advisory for closure/postclosure plan submittal will be provided in the future.

Table of Contents | Advisory 54