Vapor Intrusion Evaluation and Mitigation at the Aerojet Superfund Site
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Geosyntec is helping our client respond to various regulatory requests regarding the Aerojet Superfund Site in Rancho Cordova.

These include preparing and implementing sampling programs to support both vapor intrusion and ambient air quality investigations; evaluating sampling and other data to assess air quality impacts and the vapor intrusion pathways; supporting the implementation of mitigation measures and monitoring their effectiveness; preparing regulatory reports; and managing the project database.

Geosyntec's Scope of Services

Geosyntec performed an extensive vapor intrusion investigation for on-site buildings, which included sub-slab vapor, crawl space air, indoor air, and outdoor air sampling using a variety of sampling techniques, including grab sample collection and analysis by a mobile laboratory, time-weighted average sample collection and analysis, and real-time air sample collection and analysis using a HAPSITE gas chromatograph/mass spectrometer for source and pathway identification.  In areas where mitigation was warranted, we identified and implemented mitigation measures and to monitor their effectiveness. We managed and evaluated the extensive dataset, performed data validation, and prepared a comprehensive report documenting the field investigation, mitigation measures, and future monitoring and response action recommendations. We are continuing to perform periodic monitoring and reporting in relation to on-site building air in accordance with the report recommendations.

Geosyntec also performed an ambient air investigation in a yet-to-be-developed area of the site to assess the potential impacts of vapor intrusion through the ground surface on ambient air above and downwind of a groundwater plume. We used passive air sampling, surface flux chamber sampling, and meteorological data to complete the investigation and will perform additional passive air sampling in support of planned remedy implementation.  

As our client vacates the property, they are preparing the on-site buildings for lease or sale and have determined that they will provide vapor mitigation on all buildings. Geosyntec is performing high-volume sampling and pneumatic testing at recently vacated buildings to assist in the design, optimization, and installation of the necessary mitigation systems prior to leasing, sale, and occupancy.

Notable Accomplishments

Geosyntec developed and implemented a strategy for efficiently and effectively investigating the potential impacts from vapor intrusion on indoor air for more than 60 on-site buildings with a wide range of building features and operating conditions. We evaluated and synthesized the large volume of information generated by the investigation and applied a tiering process that we helped develop to clearly identify the status of different areas and their future monitoring needs.  Our high-volume sampling and pneumatic testing have resulted in greatly reduced efforts and costs to our client for repurposing their buildings for future tenants.

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Project Summary

  • Location: Rancho Cordova, California
  • Client: Aerojet Rocketdyne
  • Project Practice Areas: Contaminated Sites, Air Quality
  • Type of Facility: Aerospace manufacturing
  • Services Provided: On-site building indoor air investigation and ongoing monitoring, Ambient air investigation, Mitigation recommendations and effectiveness monitoring, Reporting, Sub-slab high volume sampling and pneumatic testing, Database management and data visualization
  • Type of Work: Vapor intrusion mitigation
  • Governing Regulation: Federal and state regulations