SCAQMD Rule 1466: particulate emissions from soils with toxic air contaminants

The monitors must either follow an EPA-approved equivalent method for PM10 or be approved under Rule 1466. Upwind and downwind monitors must be identical in make, model, and settings and log data at least every minute, with the precision and zero checks the rule sets out.

Owners and operators moving soil that contains toxic air contaminants of concern at a site in the South Coast district designated by the U.S. EPA as a Superfund National Priorities List site, by the California Department of Toxic Substances Control as a Brownfield or Cleanup Program site, by a state or regional water board as a Site Cleanup Program site, or by a regulatory agency as a Hazardous Material Release site. It does not apply to less than 50 cubic yards of soil or to soil removed for sampling. Wind conditions matter too: earth-moving must cease when wind speed exceeds the limit set in the rule.

Compliance is the paired upwind/downwind PM10 record at one-minute resolution, the rolling 120-minute differences against 25 µg/m³, and the documentation of every stop or control measure. The rule adjusts the comparison when the wind shifts more than 90 degrees from the prevailing direction, so wind direction has to be recorded with the dust readings.