Landfill Gas Monitoring

Screening Procedures

This document is released as guidance, subject to review and revision as necessary. The information in this document should not be considered enforceable or regulatory in nature (i.e., This document does not have the force or effect of law). Mention of trade names or commercial products does not constitute CIWMB's enforcement or recommendation.

Table of Contents

I. Introduction

1. Purpose of this Document
2. Screening Monitoring

II. Landfill Gas Screening Monitoring Procedures

1. Activities Performed in Screening Monitoring
2. Equipment to be used for Screening Monitoring
3. Monitoring System Evaluation
4. Selection of which Probes to Monitor and/or Placement of Constructed (Barhole) Probes
5. When to Monitor
6. How to Perform Screening Monitoring
7. Monitoring On-Site Structures
8. When Screening Monitoring is Complete
9. Instruments

I. Introduction

A. Purpose of this Document

The purpose of this document is to provide standardized procedures for California Integrated Waste Management Board (Board) inspectors to use when performing landfill gas (LFG) screening monitoring* during routine disposal site inspections. The standardization and simplification of the field gas monitoring procedures are intended to create an acceptable level of sureness in a site’s compliance status with respect to the State Minimum Standards (SMS) for LFG monitoring. The initial monitoring (screening monitoring) process will also provide a basis for determining whether it is necessary to conduct supplemental enhanced monitoring before making a determination of compliance with SMS. This document presumes that each inspector has already had some experience in conducting disposal site inspections, including LFG screening monitoring.  

Disposal site inspectors need to sample for LFG in the ground at the permitted facility boundary and in the structures within the permitted boundaries of a disposal site while conducting eighteen month; closed, illegal and abandoned site; or pre-permit inspections. Title 27 California Code of Regulations (27 CCR) Section 20919.5 requires all municipal solid waste landfill operators to ensure that the concentration of methane gas generated from their landfill does not exceed 1.25 percent (by volume in air) in all on site enclosed structures, excluding LFG control structures, nor 5% (by volume in air) at the property boundary (down to the maximum depth of waste within 1000 feet of the monitoring point)

Title 27 CCR Section 20919 requires operators of disposal sites to conduct monitoring and implement control measures to limit LFG migration if either an EA, the Board, or a Local Fire Authority notifies them that there is cause to believe that a hazard or nuisance may be created by LFG. Sections 20919 and 20919.5 apply to municipal solid waste landfills. Section 20919.5 does not apply to disposal sites that are not municipal solid waste landfill units as defined in 27 CCR Section 20164.

*  Please note that due to the variety of instruments in the field (Landtech, GMI, etc.) as well as different methods used by the technicians and inspectors, detected gas levels may differ between instruments.  

Table of Contents

B. Screening Monitoring

Screening monitoring defined: Routine expedient field monitoring to determine a LFG control violation, area of concern or if supplemental enhanced monitoring is required.

LFG screening is routinely conducted during facility inspections to determine if there is a LFG migration that could constitute a violation, area of concern or to determine if it is necessary to conduct further monitoring to verify that such violation exists. This monitoring is conducted whether or not a monitoring system is in place, on-site. A monitoring system usually consists of a series of in ground LFG monitoring wells installed around the permitted facility boundary. The probes should not be connected to or be in the vicinity of any negative pressure (vacuum) source.  

An example of a basic multilevel well is shown in Diagram 1:

 

Diagram 1

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