TH&Co conducts human health risk assessments ranging from screening level assessments to fully integrated deterministic and probabilistic risk assessments.  TH&Co routinely incorporates analytical, semi-analytical, and numerical unsaturated and saturated zone fate-and-transport modeling and statistical analysis into our risk assessments as warranted.

Our work through the years has garnered the respect of regulatory agencies.  Therefore, in addition to working for our private clients, who are primarily environmental consulting firms, TH&Co staff also work as subcontractors to local, State, and Federal regulatory agencies including the U.S. Environmental Protection Agency and the U.S. Forest Service through existing contracts with several of our client consulting firms.  Through these regulatory relationships, TH&Co staff remain consistently aware of frequently-changing state and federal risk assessment guidance thus allowing us to complete our work in time- and cost-effective manner.

  • Residential / Commercial Redevelopment – Fullerton, California

TH&Co used an analytical vapor intrusion model and a numerical unsaturated zone transport model coupled to an analytical saturated zone mixing model to calculate risk-based soil gas and soil concentrations for over 40 volatile organic compounds.  The soil gas risk-based concentrations assumed redevelopment of the property would involve residential and commercial/industrial use.  Potential exposure to construction worker receptors to be involved in the redevelopment process were also evaluated.  An extensive dataset of soil physical parameters was statistically evaluated to establish technically-defensible inputs to the transport models.


Kurt Fehling
President and Principal Scientist
Fehling Group, LLC
707 478-3484