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  • SDEP October Luncheon - Fighting Fire with Fire: Hexavalent Chromium Remediation using Hydrogen Sulfide Gas

SDEP October Luncheon - Fighting Fire with Fire: Hexavalent Chromium Remediation using Hydrogen Sulfide Gas

  • Tuesday, October 11, 2016
  • 11:30 AM - 1:00 PM
  • Rock Bottom Brewery - La Jolla
  • 24





Brian Hitchens

Principal Hydrogeologist
Geosyntec Consultants


Fighting Fire with Fire: Hexavalent Chromium Remediation using Hydrogen Sulfide Gas


$30 for members, $35 for non-members, add $5 if reservation is not received by 5pm the Friday before. Online registration will end at noon on the Monday before the event. Walk-ins with no reservation will be charged an extra $10 and be asked to wait until those with reservations are seated.

Please note that confirmed reservations will be invoiced regardless of attendance.


Remedial solutions for vadose zone hexavalent chromium (Cr6+) are commonly limited to dig and haul, in-situ stabilization, or soil flushing with liquid phase reductants in various forms.  However, excavation and soil mixing are not always feasible and liquid phase amendments may pose significant concerns for mobilization of impacts to groundwater.  In-situ gaseous reduction (ISGR) addresses these issues by reducing the Cr6+ impacts through the controlled injection of hydrogen sulfide (H2S) gas.  This presentation will detail the design, field-scale implementation, safety protocols and results of one of the first applications of an ISGR remedy for treatment of vadose zone Cr6+.


The project involved remediation of Cr6+ impacts in vadose zone soils beneath a former plating area to residential screening levels such that the property could be sold without use restrictions.  Initial characterization demonstrated that Cr6+ had penetrated to 45 feet below grade.  Although well above groundwater (located at 95 feet below grade), treatment of the Cr6+ through standard approaches was either infeasible due to the overlying building, or not advisable due to the potential to further mobilize Cr6+ and subsequently impact groundwater.  After direct excavation of the accessible impacted soil in the upper 10-feet, an ISGR treatment area was established around the limited area with deeper impacts.  An H2S injection/extraction skid was designed and built to inject an inline stream of H2S gas into a nested injection well, while simultaneously extracting from a ring of six soil vapor extraction wells to control and treat excess H2S gas.  Detailed monitoring and leak detection protocols were critical for safe operation of the injection system.  Following nine weeks of H2S application, post-remediation sampling of the soil within the treatment area showed excellent Cr6+ reduction meeting project remedial goals.

Speaker Information:

Brian is the Remediation Group Manager for Geosyntec’s San Diego office.  He has over 16 years of site assessment and remediation experience, focused on the implementation of in-situ remediation technologies, for hexavalent chromium, chlorinated VOCs, and polychlorinated biphenyls.   He has served as the project manager for the investigation, remedial design, remedial action implementation, and closure of many large scale industrial facilities across the Southwest. 

Brian started with Geosyntec in 2000, prior to joining Geosyntec, Brian received a BA in Geology from the College of Wooster and an MS in Structural Geology from the University of Wyoming.  He is a Professional Geologist/Certified Hydrogeologist in California and a Registered Geologist in Arizona. 



  • WALDORF SALAD - (vegetarian) arugula, tossed in honey mustard vinaigrette, topped with sun dried cherries, gorgonzola cheese, candied walnuts, celery, apple chips, and grapes 
  • AVOCADO CHICKEN SANDWICH - grilled chicken topped with avocado, swiss cheese, shredded lettuce, tomato and ranch dressing. served with french fries.
  • BREWER’S CLUB SANDWICH - roasted turkey, ham, bacon, cheddar & swiss cheeses, tomato and lettuce with chipotle mayo. served with french fries.



Rock Bottom Brewery
8980 Villa La Jolla Drive
La Jolla, CA 92037 


Directions from the North: Take I-5 or I-805 S to La Jolla Village Dr. Turn right off the freeway onto La Jolla Village Dr. Make your first left on Villa La Jolla Dr. Turn right into Rock Bottom parking lot.

Directions from the South: Take I-5 or I-805 N to La Jolla Village Dr. Turn left off the freeway onto La Jolla Village Dr. Turn left on Villa La Jolla Dr. Turn right into Rock Bottom parking lot.

Members: please remember to login in with your email and password before registering to ensure you receive the member price!


Job Postings:

Did you know that the SDEP has a job board? Now Members and Non-members can post job opportunities that their companies may have on our website.  Visit details or contact the following for more information:  

Kathy Vandenheuvel

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