Casper PCE Plume

The Casper Perchloroethylene (PCE) Plume Orphan Site is approximately 150 acres in an area that is bound to the north by the North Platte River, the south by East 5th Street, the west by Center Street, and the east by Bryan Stock Trail.  The area is comprised of residential, commercial and industrial neighborhoods.  Environmental testing in the late 1980s revealed the presence of PCE in groundwater in downtown and north Casper, as well as in the indoor air of some homes.  

The Wyoming Department of Environmental Quality (DEQ) has designated the Casper PCE Plume Orphan Site as a high priority orphan site.  The designation is due to the number of people in proximity to the plume, the discharge of the plume into the North Platte River, and the carcinogenic nature of PCE.  When funding has been available the DEQ has continued to investigate, monitor, and remediate the plume. 

Currently, the DEQ is monitoring the effectiveness of the remedies implemented to remediate the PCE plume.  If you have any questions about the project, please contact the Project Manager, Matt Buchholz at 307-777-8937 or at

Recent Public Meetings:

  • March 28, 2017: The DEQ held a public meeting to inform concerned parties about the plan to remediate the PCE plume.

Site Investigation Milestones:

  • November – December 2009: The DEQ installed groundwater monitoring wells and soil vapor sampling points throughout the study area.
  • March 2010 – March 2011: The DEQ tested indoor air and subslab soil gas at potentially affected properties.
  • June 2010 – August 2011: The DEQ installed indoor air mitigation systems at residential and commercial buildings.
  • August 2011: Installation of additional groundwater wells along the northern portion of the plume.
  • Spring 2014: The DEQ used High Resolution Site Characterization (HRSC) techniques to investigate a source area to acquire information that would allow a Remedial Alternatives Evaluation to be completed.  During this work the DEQ was able to show another PCE plume (further upgradient) was contributing to the Casper PCE plume. 
  • Spring 2015: The DEQ approved the Source Characterization Report (1/9/15), allowing the DEQ to evaluate remedial alternatives.
  • May 2016: The DEQ approved the Remedial Alternatives Evaluation Report (RAER) (5/9/16), which included a recommendation to do additional HRSC at the furthest upgradient source.  The RAER suggested implementing Soil Vapor Extraction (SVE) in conjunction with Enhanced In-Situ Bioremediation (EISB) for the source of the plume, and Monitored Natural Attenuation (MNA) for the rest of the plume.
  • July 2016: The DEQ completed the HRSC investigation (7/11/16) at the furthest upgradient source.
  • November 2016: The DEQ approved the SVE work plan (11/1/16).
  • May 2017: The DEQ approved the EISB work plan (5/3/17).
  • July 2017: The DEQ received the SVE installation report (7/10/17).
  • July 2017: The DEQ approved the MNA work plan (7/13/17).
  • October 2017: The DEQ received the EISB remedy completion report (11/17/17).


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