Air Monitoring During Holidays

December 23, 2019

Over several days during this holiday season, DTSC is authorizing Ascon to modify their air monitoring schedule to allow air quality professionals time with their families and friends.

Work at Ascon has stopped since June 2019. Prior to this work stoppage and before the stoppage occurred, air monitoring has not found levels of contaminants that pose a public health. Dust and odor suppressants continue to be applied to the site. On-site and off-site air monitoring continues.

The limited pause in air monitoring will only occur when no work occurs at Ascon and students are not scheduled to be at any activities at Edison High School or Eader Elementary Schools. Ascon will also continue to maintain security on the site.

Pauses in air monitoring will occur on the following dates:

  • December 24 – after 12:00 pm noon
  • December 25
  • December 28
  • December 29
  • December 31 – after 12:00 noon
  • January 1

On-site and off-site air monitoring includes samples for Volatile Organic Compounds (VOCs) and dust (PM or particulate matter). Monitoring complies with the Department of Toxic Substances (DTSC) approved air monitoring program. All VOC concentrations detected are below levels that present a threat to public health.

Dust monitoring has found levels below the State of California’s standard of 50 ug/m3 (micrograms, or one-millionth of a gram, per cubic meter air) averaged over 24-hours. Limited, short-term monitoring results above 50 ug/m3 have occurred. However, these results have not lasted for more than a few hours. These results are also associated with a heavy marine layer affecting air monitoring equipment. These air monitoring results consistently show that the Ascon site is not associated with any levels that present a public health threat.

Since October 2019, a number of field actions were conducted to implement best practices for stormwater management. These include the installation of straw wattle (straw tubing) and the application of mulch in previously excavated zones. The mulch is applied as a slurry with a plant-based binder that hardens and helps hold the mulch in place.

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