Eric Sonsthagen, PE

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Eric Sonsthagen, PE

Senior Project Engineer



Eric Sonsthagen is a Senior Project Engineer with Blackstone Environmental. Since joining the team in 2022, Eric has provided solid waste/environmental engineering to Blackstone’s growing client base. He has experience in permitting, design, and construction oversight of landfill cell construction, landfill closures, and landfill gas extraction systems.

Eric enjoys jigsaw puzzles and spending time with his family.


  • B.S. Chemical Engineer (Environmental Option), University of Wyoming, 1999

Registrations & Certifications

  • Professional Engineer - IA, NE, WA
  • 40-Hour HAZWOPER
  • Excavation and Trenching Competent Person
  • CPN Nuclear Density Gauge Certification
  • Certified CQA Geosynthetic Materials and Compacted Clay Liner Inspector


Calculating landfill gas emissions, greenhouse gas (GHG) emissions, and estimating
recoverable landfill gas. Permitting experience includes performing landfill
locational analysis, solid waste permit and renewal applications, Title V permit and
renewal applications, minor and major permit modifications, notice of
construction applications, New Source Performance Standard (NSPS) reporting,
emission inventories, compliance evaluations, and regulatory assistance. Closure and post-closure and financial assurance cost estimating.


Member, American Institute of Chemical Engineers (AlChE), Member, Solid Waste Association of North America (SWANA)