74 : 36 : 07 : 103 . Tier 4 nonmethane organic compound emission rate for existing municipal solid waste landfills. Tier 4 is allowed only if the owner or operator can demonstrate that nonmethane organic compound emissions are greater than or equal to thirty-four megagrams per year but less than fifty megagrams per year using Tier 1 or Tier 2. If both Tier 1 and Tier 2 indicate nonmethane organic compound emissions are fifty megagrams per year or greater, Tier 4 cannot be used and the owner or operator must meet the criteria in subdivision (8) of this section . If Tier 4 is used, the owner or operator must demonstrate that surface methane emissions are below five hundred parts per million. Surface emission monitoring must be conducted , on a quarterly basis , using the following procedures:

1. (1) The owner or operator must measure surface concentrations of methane along the entire perimeter of the landfill and along a pattern that traverses the landfill at no more than thirty-meter intervals using an organic vapor analyzer, flame ionization detector, or other portable monitor meeting the specifications provided in § 74:36:07:115;
2. (2) The background concentration is determined by moving the probe inlet upwind and downwind at least thirty meters from the waste mass boundary of the landfill;

3. (3) Surface emission monitoring must be performed in accordance with 40 C.F.R. Part 60, Appendix A, Method 21, section 8.3.1 (July 1, 2024), except the probe inlet must be placed no more than five centimeters above the landfill surface. The constant measurement of distance above the surface should be based on a mechanical device:

   1. (a) The owner or operator must use a wind barrier when onsite average wind speed exceeds four miles per hour or two meters per second or gust exceed ten miles per hour. Average on-site wind speed must be determined in an open area at five-minute intervals using an on-site anemometer with a continuous recorder and data logger for the entire duration of the monitoring event. The wind barrier must surround the surface emission monitor and be placed on the ground to ensure wind turbulence is blocked. Surface emission monitoring cannot be conducted if average wind speed exceeds twenty-five miles per hour; and
   2. (b) Landfill surface areas where visual observations indicate elevated concentrations of landfill gas and all cover penetrations must be monitored using a device meeting the specifications provided in § 74:36:07:115;
4. (4) Each owner or operator seeking to comply with the Tier 4 provisions in subdivision (6) of this section must maintain records of surface emission monitoring and submit a Tier 4 surface emissions report;
5. (5) If there is any measured concentration of methane of five hundred parts per million or greater from the surface of the landfill, the owner or operator must submit a gas collection and control system design plan within one year of the first measured concentration of methane of five hundred parts per million or greater from the surface of the landfill and install and operate a gas collection and control system according to §§ 74:36:07:106 and 74:36:07:109 within thirty months of the most recent nonmethane organic compound emission rate report in which the nonmethane organic compound emission rate equals or exceeds thirty-four megagrams per year based on Tier 2;
6. (6) If after four consecutive quarterly monitoring periods at a landfill, other than a closed landfill, there is no measured concentration of methane of five hundred parts per million or greater from the surface of the landfill, the owner or operator must continue quarterly surface emission monitoring;
7. (7) If after four consecutive quarterly monitoring periods at a closed landfill there is no measured concentration of methane of five hundred parts per million or greater from the surface of the landfill, the owner or operator must conduct annual surface emission monitoring; and

8. (8) If a landfill has installed and operates a collection and control system that is not required, then the collection and control system must meet the following criteria:

   1. (a) The gas collection and control system must have operated for at least six thousand five hundred seventy out of eight thousand seven hundred sixty hours preceding the Tier 4 surface emissions monitoring demonstration; and
   2. (b) During the Tier 4 surface emissions monitoring demonstration, the gas collection and control system must operate as it normally would to collect and control as much landfill gas as possible.

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.