Testing or monitoring for vapors within the excavation area may be used as a release detection method if all of the following conditions are met:

1. (1) The materials used as backfill in the excavation zone (e.g., gravel, sand, crushed rock) are sufficiently porous to readily allow diffusion of vapors from releases into the excavation area;
2. (2) The stored regulated substance (e.g., gasoline) or a tracer compound placed in the tank system is sufficiently volatile to result in a vapor level that is detectable by the monitoring devices located in the excavation area in the event of a release from the UST system;
3. (3) The measurement of vapors by the monitoring device cannot be rendered inoperative by the groundwater, climatic conditions, or soil moisture so that a release could go undetected for more than 30 days; and

4. (4) The level of background contamination in the excavation area cannot interfere with detection of releases from the UST system.

   The vapor monitors must be designed and operated to allow the threshold level to be preset specifically for the type of regulated substance stored in the tank system and must be capable of detecting any significant increase in concentration of total hydrocarbons above background levels.

   In the UST excavation area, the site must be assessed before installation of the system to assure compliance with the requirements of this section and to establish the number and positioning of monitoring wells that will detect releases within the excavation area from any portion of the UST system. The monitoring wells must be clearly marked and secured to avoid unauthorized access and tampering.

Source: 14 SDR 76, effective November 29, 1987; transferred from § 74:03:28:11, 18 SDR 62, effective October 10, 1991; transferred from § 74:03:28:11.02, July 1, 1996; 44 SDR 192, effective June 28, 2018.

General Authority: SDCL 34A-2-93 , 34A-2-99.

Law Implemented: SDCL 34A-2-98 , 34A-2-99.

Prior versions effective: 1996-07-01.