Aerocraft Heat Treating Co., Inc. – a metal-finishing facility in Paramount — has been ordered to shut down all metal processing equipment and operations with the potential to emit the toxic compound hexavalent chromium.
Aerocraft, at 15701 Minnesota Ave., was ordered to curtail operations by midnight of March 16, 2017 because South Coast Air Quality Management District air monitoring data found levels of the compound above a trigger threshold of 1.0 nanograms per cubic meter.
The level is an average of three samples collected over a period of about a week. The threshold, agreed to by Aerocraft, was specified in an administrative order adopted by the independent SCAQMD Hearing Board on Dec. 16, 2016.
This is the fourth time since the order was adopted that Aerocraft has had to curtail operations due to exceeding the threshold in the order. Prior curtailments occurred from Jan. 19 to Jan. 27; Feb. 14 to Feb. 21; and March 2 to March 7.
The following table shows recent levels of hexavalent chromium at a SCAQMD monitor just outside of Aerocraft:
Aerocraft will not be able to resume operations of any equipment with the potential to emit hexavalent chromium until SCAQMD determines that the average of the three most recent samples, collected over about one week, are below 1.0 nanograms per cubic meter.
SCAQMD, in conjunction with the California Air Resources Board, also has monitored air quality at several schools in Paramount. Recorded average levels at those schools have been below 0.3 nanograms per cubic meter since sampling started on Dec. 23, 2016.