74 : 36 : 07 : 101 . Tier 2 nonmethane organic compound emission rate for existing municipal solid waste landfills. The owner or operator of an existing municipal solid waste landfill must install at least two sample probes per hectare, evenly distributed over the landfill surface that has retained waste for at least two years. If the landfill is larger than twenty-five hectares in area, only fifty samples are required. The probes should be evenly distributed across the sample area. The sample probes should be located to avoid known areas of nondegradable solid waste. The owner or operator must collect and analyze one sample of landfill gas from each probe to determine the nonmethane organic compound concentration using 40 C.F.R. Part 60, Appendix A -7 , Method 25 or 25C (July 1, 20 24 ). Taking composite samples from different probes into a single cylinder is allowed , provided that equal sample volumes are taken from each probe. For each composite, the sampling rate, collection times, beginning and ending cylinder vacuums, or alternative volume measurements must be recorded to verify that composite volumes are equal. Composite sample volumes may not be less than one liter unless evidence is provided to substantiate the accuracy of smaller volumes. Terminate compositing before the cylinder approaches ambient pressure where measurement accuracy diminishes. If more than the required number of samples is taken, all samples must be used in the analysis. The landfill owner or operator must divide the nonmethane organic compound concentration from Method 25 or 25C by six to convert from nonmethane organic compound concentration as carbon to nonmethane organic compound concentration as hexane. If the landfill has an active or passive gas removal system in place, Method 25 or 25C samples may be collected from these systems instead of surface probes , provided the removal system can be shown to provide sampling as representative as the two sampling probe per hectare requirement. For active collection systems, samples may be collected from the common header pipe. The sample location on the common header pipe must be before any gas moving, condensate removal, or treatment system equipment. For active collection systems, a minimum of three samples must be collected from the header pipe. The owner or operator must determine the site-specific nonmethane organic compound concentration using the following sampling procedure:

1. (1) Within sixty days after the date of determining the nonmethane organic compound concentration and corresponding nonmethane organic compound emission rate, the owner or operator must submit the results;
2. (2) The owner or operator must recalculate the nonmethane organic compound mass emission rate using the appropriate equation in § 74:36:07:99 using the average site-specific nonmethane organic compound concentration from the collected samples instead of the default value;
3. (3) If the resulting nonmethane organic compound mass emission rate is less than thirty-four megagrams per year, the owner or operator must submit an estimate of nonmethane organic compound emissions in the annual nonmethane organic compound emission rate report. The site-specific nonmethane organic compound concentration must be retested every five years; and

4. (4) If the nonmethane organic compound mass emission rate, as calculated using the Tier 2 site-specific nonmethane organic compound concentration, is equal to or greater than thirty-four megagrams per year, the owner or operator must:

   1. (a) Submit a gas collection and control system design plan within one year and install and operate a gas collection and control system within thirty months according to §§ 74:36:07:106 and 74:36:07:109;
   2. (b) Determine a site-specific methane generation rate constant and recalculate the nonmethane organic compound emission rate using the site-specific methane generation rate using the Tier 3 procedures specified in § 74:36:07:102; or
   3. (c) Conduct a surface emission monitoring demonstration using the Tier 4 procedures specified in § 74:36:07:103.

Source: 46 SDR 64, effective November 25, 2019 ; 52 SDR 27, effective September 17, 2025 .

General Authority: SDCL 34A-1-6 , 34A-1-18 .

Law Implemented: SDCL 34A-1-18 .

Prior versions effective: 2019-11-25.