Maricopa County is proposing to update Rule 316 [Nonmetallic Mineral Processing] and Rule 320 [Odors and Gaseous Air Contaminants] in 2018.

The County has held multiple stakeholder workshops for each of the rules and is proposing the following updates to the rules:

Rule 320

  • The proposed rule will focus on emissions of H2S, sulfur in fuel, asphalt day tankers and/or tar kettles, and reduction of animal matter.
  • This update is due to the current language being broad, unenforceable and MCAQD's overall intent to improve regulations.
  • Additionally, MCAQD states that odors are not considered regulated air pollutants and plans to remove the relevant language from the rule, however, it will still investigate any odor related complaints.

Rule 316

  • All fugitive dust control measures for nonmetallic mineral processing and related operations will be consolidated in a single rule - Rule 316.
  • MCAQD will incorporate a 20% opacity limit for emissions of blue smoke.
  • The rule will include control requirements for dry material storage silos which would be applicable to cement, fly ash, lime, and other pozzolan materials.
  • The rule will include more flexible compliance options for wind-blown dust, alternative trackout control requirement, alternative minimum moisture contents for products feeding hot mix asphalt plants, and an alternative test method for soil moisture testing.
  • Emission limits from NSPS Subpart OOO will also be included in the proposed rule.