Ascon Final Remedy Work
Work Progress | Near Real-Time Air Monitoring Data | Air Monitoring During Construction of the Engineered Cap | Community Resources
Ascon Final Remedy Updates
The Ascon team has finalized a Restart Work Plan with the Department of Toxic Substances Control (DTSC). Work began in October 2024 and is expected to take approximately 27 months to complete.
Final Remedy Work Progress
After Final Remedy work is completed, the Ascon Site will remain fenced open space. Learn more about the future of the Site here.
Air Monitoring During Construction of the Engineered Cap
The Department of Toxic Substances Control (DTSC) has reviewed monitoring data collected since 2019. Volatile Organic Compound (VOCs) and dust levels have remained well below health-protective limits throughout the project. All air monitoring data are reviewed by DTSC and posted to our Actively Monitoring Air Quality webpage.
In the project’s current phase, construction of the engineered cap, we are continuing air monitoring using:
- Six onsite perimeter stations that will continue to measure for dust and total VOCs.
- Near real-time air monitoring results during Final Remedy work are posted at the bottom of this page. You can view all historical air monitoring results dating back to 2019 here.
Near Real-Time Air Monitoring Data
We collect near real-time air monitoring data through a telemetry-enabled air monitoring system. These data are collected during work hours, from 7 a.m. to 6 p.m., Monday through Friday.
A system of remote sensors around the perimeter of the Site that captures air quality data, such as total VOCs and dust, upwind and downwind of the work in near real-time.
An “action level” is an amount of a substance established by regulatory agencies that is protective of public health. Action levels help determine if work on-site is creating an issue, usually focusing on the “site contribution” (downwind minus upwind levels).
Site contributions are displayed and compared to the Site action levels, confirming air concentrations are below action levels. If a brief telemetry reading is above an action level, it does not mean that there was harmful exposure or that the community’s health is at risk. It means controls must be reviewed.
Air monitoring action levels are used during the work at Ascon to guide mitigation actions, to stop work actions and to prompt increased actions to control potential odor, emissions or dust. For the purpose of evaluating potential community exposures, air data are evaluated over 24-hour periods and longer. The air data are submitted to DTSC, available for review by South Coast Air Quality Management District (SCAQMD) and shared on our Actively Monitoring Air Quality webpage.
Air monitoring screening levels were approved by DTSC and reviewed by SCAQMD. They take several factors into account, including the type of substances that may be present, the detections in the air and how long the potential exposure lasts. The levels are set to be protective of potentially sensitive members of the community (e.g., children, pregnant women, those with health concerns) and are for both short-term and long-term exposures, such as daily exposure over a lifetime.
Onsite Final Cleanup Work Telemetry Results
To view data from the last week, last month or all data, click on the 
icon and select the timeframe you would like to view for both dust and total VOCs.
How to read the telemetry results
If a dust or VOC reading is above their respective action level, it does not mean that the communities health is at risk, but allows onsite teams to adjust mitigation efforts.
Dust
The results during work hours show Site contribution dust levels in two-hour intervals. Telemetry is a tool that can guide and inform active work. If a dust reading is 50 ug/m3 above background, it does not mean that the community’s health is at risk but allows onsite teams to adjust dust mitigation efforts.
Air monitoring action levels were approved by DTSC and the SCAQMD for total dust.
VOC
The results during work hours show Site contribution total VOC levels in two-hour intervals. Telemetry is a tool that can guide and inform active work. If a reading is above an action level, it does not mean that the community’s health is at risk but allows onsite teams to adjust work and mitigation efforts.
Air monitoring action levels were approved by DTSC and the SCAQMD for total VOCs.
Final Restart Work Resources
Have a Question or Concern?
Please contact the Ascon community information line at 714-388-1825 or email info@asconhb.com. If there is a potential emergency, please call 911. Sign up for AsconAlert, an opt-in community alert system for the Ascon project here.
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