1

MEMORANDUM

To: Hillary Ward, U.S. EPA, OAQPS, Sector Policies and Programs Division

Docket EPA-HQ-OAR-2014-0451

From: Eastern Research Group

Date: July 2015

Subject: Analysis of Surface Exceedances from California La ndfills under the New Source

Performance Standards and the California Landfill M ethane Rule



### 1.0 Introduction
This memorandum summarizes data that the EPA receiv ed related to enhanced surface emissions monitoring under the California Landfill Methane Ru le (CA LMR) in order to assess the environmental benefits of modifying the surface emission monitori ng (SEM) requirements in the MSW Landfills New Source Performance Standards (NSPS) and Emission Gu idelines (40 CFR part 60, subparts XXX and Cf).
The current NSPS and Emission Guidelines SEM provis ions require a traverse of the landfill at 30 meter (98 ft.) intervals; reporting of methane concentrat ions over 500 ppmv (exceedances), and monitoring during typical meteorological conditions.
The CA LMR requires a tighter traverse pattern of 2 5 ft.; reporting of instantaneous methane concentrations over 500 ppmv or greater; reporting of integrated methane concentrations of 25 ppmv or greater within 50,000 sq. ft. grids; and restric tions on monitoring when wind speed exceeds 5 mph average and 10 mph instantaneous or within 72 hours of measurable precipitation unless a variance is provided. In the July 2014 proposed NSPS revisions (40 CFR part 60 subpart XXX) and the Advanced Notice of Proposed Rulemaking for revisions to the MSW Landfills Emission Guidelines, the EPA requested comment for additional information on the emission reductions and costs associated with enhanced monitoring approaches.
The current NSPS/ Emission Guidelines and CA LMR re quire corrective action for exceedances. When a landfill shows an exceedance, the landfill must mak e repairs or adjustments and recheck at 10 days and 30 days to confirm no exceedances continue to occur . If an exceedance cannot be corrected with a repair or adjustment, the gas collection and contro l system (GCCS) must be expanded. 

### 2.0 Summary of Available Data The EPA received a report that compares the current NSPS SEM approach to the CA LMR approach, hereinafter referred to as the 2014 Surface Monitor ing Report

. 1 The 2014 Surface Monitoring Report focuses on overall number of exceedances per acre ( expressed as a percentage), comparing surface monitoring results under the CA LMR to the MSW Land fills NSPS or Emission Guidelines. The report does

1 SCS Engineers. A Comparison of Monitoring Results for California Landfills Under the New Source Performance Standards and the California Landfill Methane Rule. October 2014. See Appendix A of this memo for a copy of the report.2

not provide data to determine the magnitude of emis sion reductions that might result from the greater exceedances.
Because the 2014 Surface Monitoring Report focuses on overall exceedances across a pool of landfills, the EPA requested background data used to develop t he summary analysis in the report. Waste Management provided the background data to EPA in F ebruary 2015, hereinafter referred to Supporting Data Tables for 2014 SEM Report, and the data are i ncluded in Appendix B to this memorandum. These data were analyzed, as discussed below to determine whether enhanced SEM under the CA LMR identified more landfills with exceedances compared to the NSPS SEM. Although compliance monitoring reports of both the current and enhanced approaches were available to compare for certain landfills, the reports represent different time periods. 2 

### 3.0 Findings and Analysis The conclusions of the 2014 Surface Monitoring Repo rt rely largely on a low percentage of overall exceedances across a group of landfills, with empha sis on the even smaller percentage of exceedances resulting in gas collection and control system (GCC S) expansion after 120 days, to support why the EPA should not adopt a tighter surface emissions monito ring (SEM) program.
This section summarizes the analysis of three compo nents of the enhanced SEM in the CA LMR compared to the SEM requirements in the current NSP S on a landfill-by-landfill basis as compared to an aggregate basis of a group of landfills. The spread sheets used to generate these summaries are availab le in Appendix C of this report. 

### 3.1 Impact of a Tighter Traverse Pattern (98-foot v s. 25-foot) The 2014 Surface Monitoring Report indicates 1.6% e xceedances under the current approach (based on 212 reports and 27,140 acres monitored) and 4.4% ex ceedances under the enhanced approach (from 357 reports with 44,607 acres monitored). The repor t indicates 42 landfills were subject to the NSPS SEM monitoring requirements.
The Supporting Data Tables for 2014 SEM Report show 29 of the 42 NSPS landfills had monitoring reports based on both the current and the CA LMR ap proach. Data indicate over 60% of these landfills show exceedances only under the CA approach or grea ter exceedances with the CA approach. Specifically:

• Seven landfills show exceedances only under the CA approach 3 ;

• 10 show greater exceedances under CA approach;

• Four show lower exceedances under the CA approach; and

• Eight show no exceedances under either approach.
Further, for those landfills with greater exceedanc es under the CA LMR, exceedances were on average 180% more frequent, as shown in Table 1. While the data do provide evidence of greater exceedances, we were not able to determine the magnitude of emis sion reductions that might result from the CA LMR approach.

2 Current approach based on reports covering 8 quart ers (3rd quarter 2009 through mid-2011); Enhanced approach based on reports 10 quarters (mid-2011 thr ough end of 2013).

3 All of these landfills are located in arid areas ( 25 inches or less of annual rainfall). All of these landfills have a waste-in-place amount over 2.5 million tons.3

Table 1. Average Traverse Exceedances per Report, by Repor t Type

Landfill ID Average # of

Exceedances per NSPS Report* Average # of

Exceedances per LMR Report * Exceedance

% Diff**

Landfill 39 14.7 5.6 -62% Landfill 50 14.5 32.5 124% Landfill 19 4.0 20.3 408% Landfill 30 8.8 5.6 -36% Landfill 66 8.3 28.9 247% Landfill 02 5.3 6.9 29% Landfill 57 7.5 10.1 35% Landfill 24 2.7 17.6 558% Landfill 47 2.3 6.1 163% Landfill 43 4.0 7.0 75% Landfill 69 1.5 1.2 -20% Landfill 04 2.0 1.8 -13% Landfill 37 2.0 5.0 150% Landfill 60 1.0 1.3 25% * For monitoring reports with >0 exceedances. ** Negatives indicate more exceedances per report f or NSPS than LMR. Notes:

• Exceedances from surface penetrations were extracte d from the total exceedances in order to get the number of exceedances attributed to the tra verse pattern alone.

• **Bold text shows landfills having more than double t he average number of exceedances per**  **report for LMR when compared to NSPS.**

The environmental benefits of locating additional e xceedances under a tighter traverse pattern could not be quantified based on available data. The 2014 Surface Monitoring Report identified 0.3% of the total acres monitored required GCCS expansions. How ever, it is noted that since all leaks require corrective action, even if a GCCS is not required t o be expanded, a landfill owner/operator’s response to a surface leak would be a combination of: 1) surfac e repairs (specialized clay to seal cracks or bases of wells) and/or 2) adjustments to GCCS, for example i ncreasing the vacuum to pull more gas through the GCCS or repairing a blockage in the GCCS to avoid l eaks to the surface. Both of these corrective actio ns will result in an environmental benefit, even if th e GCCS does not have to be expanded. 

### 3.2 Effect of Adding an Integrated Reading to Excee dance Criteria (at or above 25 ppmv) The Supporting Data Tables for the 2014 Surface Mon itoring Report indicate that 703 out of 32,946 grid s monitored at NSPS landfills (2.1% of grids) had an exceedance of the 25 ppmv limit.4

• 201 of the 703 grids (28.6%) also had an exceedance of the 500 ppmv instantaneous criteria, indicating significant overlap in how the instantan eous and integrated readings identify locations with surface emission leaks.

Of the 29 landfills that monitored under both the c urrent and the CA approach, the data indicate:

• One landfill shows an exceedance of only the integr ated reading

• Three landfills show no exceedances under current N SPS approach, but show exceedances under both the integrated reading and the instantan eous reading under the CA approach

• Seven landfills show exceedances under both the int egrated reading and instantaneous readings under both the current NSPS and CA approaches. 4

These findings suggest that adding an integrated re ading to exceedance criteria (at or above 25 ppmv) identified minimal additional exceedances. 

### 3.3 Effect of Wind Speed Limitations During SEM Because the CA approach restricts monitoring to occ ur below specified wind speeds, landfills may request approval for alternatives to these restrict ions when winds in excess of the specified limits a re consistently being measured at the surface of the l andfill.

• 2014 Surface Monitoring Report indicates 72.6% of t he landfills evaluated required a permanent alternative for wind speed due to conditions at the site.

• Of the 29 landfills that monitored both the current and the CA approach, 76% of the landfills (22/29) required an alternative approach for wind s peed under the CA approach.
These findings suggest that a large majority of lan dfills could not consistently find monitoring perio ds that met the wind speed restrictions in the CA LMR rule.

4 All but one of these seven landfills are located i n arid areas (25 inches or less of annual rainfall)

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