Washington Administrative Code › Title 173 - Ecology, Department of (See also Titles 197, 317, 372, and 508) › Chapter 173-408 - Landfill Methane Emissions › Section 173-408-990 - Appendix II. OTM-51 - UAS Application of Method 21 for Surface Emission Monitoring of Landfills

Current through Register Vol. 24-14, July 15, 2024
1.0
Background on OTM-51
This method provides procedures for use of unmanned aerial
				systems (UAS) to perform surface emissions monitoring for MSW landfills. This
				method was submitted by Sniffer Robotics, LLC to EPA's Office of Air Quality
				Planning and Standards Measurement Technology group and was included into the
				Other Test Method (OTM) category on EPA's Air Emission Measurement Center
				website on 12/15/2022.
OTM-51 is approved for use at MSW landfills for several federal
				regulations and is approved for use under this chapter, subject to the caveats
				and additional information specified in section 11.0 of this appendix.
The following application of OTM-51 is only approved for the
				purpose of compliance with the surface emission monitoring requirements of this
				chapter, and does not supersede any approved methods, requirements, or
				regulations regarding the use of OTM-51 for other federal, state, and local
				laws or regulations.
2.0
Scope and Application
Scope: This method is an alternative test method for
				determining compliance with the surface methane operational standard for
				landfills in lieu of procedures set forth pursuant to WAC 173-408-120
				(1)(a).
Analytes
Analyte
CAS Number
Methane (CH4)
74-82-8
3.0
Summary of Method
This alternative test method seeks to replicate, to the
				greatest extent possible, EPA Method 21, but automates surface emission
				monitoring by utilizing a methane detection payload on an "unmanned aerial
				system (UAS)," as defined in WAC 173-408-020, coupled with a ground level to
				UAS sampling system. The methane detector payload includes a hose and custom
				nozzle design that, when carried by the UAS, places the nozzle inlet within
				5-10 cm of the ground. The UAS transmits the geolocated methane readings to the
				operator via a wireless communication system. The UAS is used to sample large
				areas for "increased meter readings," as defined in WAC 173-408-020, each of
				which are then inspected using EPA Reference Method 21.
4.0
Equipment and Supplies
(a) The methane detection payload shall have
			 the following specifications:
(i) The methane
			 detection payload shall collect and respond to methane in the air samples;
			 standoff or remote detection technologies are not applicable. Detector types
			 that may meet this requirement include, but are not limited to, flame
			 ionization, nondispersive infrared absorption (NDIR) and tunable diode laser
			 absorption spectroscopy (TDLAS).
(ii) The methane detection payload shall be
			 capable of measuring methane in the range from zero through the increased meter
			 reading up to and above the exceedance limit of 500 ppm specified in this
			 chapter.
(iii) The scale of the
			 methane detection payload shall be readable to ±2.5 percent of the
			 increased meter reading level of 200 ppm methane.
(iv) The methane detection payload shall be
			 equipped with a pump that provides the detector a constant sample flow rate.
			 The nominal sample flow rate, as measured at the sample probe nozzle, shall be
			 at least 0.5 l/min when the probe is fitted with the full impedance stack of
			 tubing, filters, and nozzle.
(v)
			 The methane detection payload shall have a known instrument-only response time.
			 Instrument-only response time shall be measured for the methane detection
			 instrument prior to being placed into service but does not have to be repeated
			 at subsequent intervals. Instrument-only response time shall be measured by
			 measuring the T90 response time for a minimum of five unique tube lengths less
			 than 10m, fitting a linear regression to the measured T90 response times and
			 recording they-intercept as the instrument only response time if the
			 r2 of the linear regression is greater than
			 0.95.