October 20, 2021

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Dariusz Chlebica and David Jensen to Present at AEHS Foundation International East Coast Conference

Dariusz Chlebica, P.G. (Massachusetts) will present "A Comprehensive Remedial Approach for a Former Manufacturing Facility" and David Jensen (Massachusetts) will present "How Much Data is Enough? Designing an Optimized Active Vapor Intrusion Mitigation System with a Limited Conceptual Site Model" at the Association for Environmental Health and Sciences (AEHS) Foundation's virtual International Conference on Soils, Sediments, Water, and Energy on October 20, 2021.

Dariusz Chlebica is a Project Geologist based in Massachusetts with experience in environmental consulting and hydrogeology. Dariusz has performed extensive research on groundwater and bedrock wells, which he has presented at past NGWA conferences and elsewhere.

David Jensen is a Senior Staff Engineer based in Massachusetts with experience in environmental site investigations and remediation across the U.S. He has led vapor intrusion investigations involving traditional sub-slab soil gas sampling and high-volume sampling. David has also designed and overseen the installation of multiple active vapor intrusion mitigation systems in existing industrial and commercial buildings.

The Annual Conference on Soils, Sediments, Water and Energy is a national conference that attracts a wide variety of representation from state and federal agencies, military, industry (including railroad, petroleum, transportation, and utilities), environmental engineering, environmental consulting, and academia. A strong and diverse technical program is developed each year in concert with a variety of educational, social, and networking opportunities.

The AEHS Foundation is a non-profit, member-supported, professional organization. Their purpose is to facilitate communication and foster cooperation among professionals concerned with the challenges of soil, sediment, and water assessment, clean-up, and protection.


A Comprehensive Remedial Approach for a Former Manufacturing Facility
Presenter: Dariusz Chlebica
Date: October 20, 2021 from 10:30 – 11:00 a.m. EST
The development of brownfield sites with a complex history of contaminant releases resulting in soil, groundwater, and indoor air impacts presents many challenges to property owners and consultants. The complexities of the impacts in multiple environmental media require diligence and focus on a property-wide remedial approach to be formulated and implemented prior to achieving regulatory closure. Geosyntec implemented a comprehensive, property-wide remediation approach at a former manufacturing facility in the metro Boston area, which occurred in parallel to Site development activities for commercial use. The aggressive remedial approach included excavation of trichloroethene (TCE) impacted material, enhanced in-situ bioremediation (EISB) to remediate chlorinated volatile compounds (CVOCs) in groundwater, a soil vapor extraction (SVE) to mobilize and remove CVOCs from the vadose zone, and sub-slab depressurization (SSD) to mitigate vapor intrusion to site buildings. The EISB amendment injections of emulsified vegetable oil (EVO), emulsified zero-valent iron (EZVI), and lactic acid and KB-1 bacterial culture resulted in a 99% reduction in the groundwater CVOC concentrations through reductive dechlorination. The SVE system operated for approximately 20 months, removed approximately 18 pounds of volatile compounds, and resulted in a 99% reduction in tetrachloroethene (PCE) and TCE concentrations in sub-slab soil gas. The effectiveness of the SSD systems was evaluated through four shutdown tests combined with sub-slab and indoor air sampling. The analytical results for the SSD shutdown tests indicated that the CVOC detections were below the risk-based levels. Based on successful implementation of the remedies, the site achieved a regulatory closure within five years, ahead of the anticipated schedule. This project highlights the importance of a property-wide, multi-faceted approach to site remediation, where multiple remedies are pursued in parallel to shorten the timeframe to achieve closure.

How Much Data is Enough? Designing an Optimized Active Vapor Intrusion Mitigation System with a Limited Conceptual Site Model
Presenter: David Jensen
Date: October 20, 2021 from 1:30 – 2:00 p.m. EST
When designing an optimized active vapor intrusion mitigation system (VIMS) for an existing large building, it is essential to develop a vapor intrusion conceptual site model (VI CSM). With an in-depth understanding of the VI CSM we can support a targeted mitigation approach, resulting in significant cost saving, while remaining protective of human health. However, constraints at a site may prevent the development of a complete VI CSM and it is therefore important to know what data is needed to credibly design an efficient and protective active VIMS.

In the presented case study, detections of tetrachloroethene and trichloroethene in subslab soil gas (SSG) at a 52,000 square foot industrial building renovated as a residential re-entry center required the design and installation of an active VIMS. However, soil and groundwater data could not be collected so the source of subslab concentrations was unknown, and, in addition, indoor air data indicated the VI pathway did not currently demonstrate risk to residents.

In order to supplement the limited VI CSM for the site enough to design an optimized VIMS, targeted data was collected by reviewing the building's construction and current uses, reviewing historic SSG data, and conducting modified high-volume sampling. Based on this data, the final active VIMS, designed to be protective of current and future human health, targeted depressurization of less than half of the total building footprint. Startup of the system is expected in spring 2021, and post-startup testing results as well as lessons learned will be presented.

More Information

About the event: Annual International Conference on Soils, Sediments, Water, and Energy
About the AEHS Foundation: https://www.aehsfoundation.org/
For consultation regarding environmental remediation, contact Dariusz Chlebica at This email address is being protected from spambots. You need JavaScript enabled to view it.
or David Jensen at This email address is being protected from spambots. You need JavaScript enabled to view it.
Learn more about Dariusz: Dariusz Chlebica – LinkedIn
Learn more about David: David Jensen – LinkedIn