Khaled Chekiri, PhD, P.E., P.Eng., recently retired as a senior environmental engineer at the Dragun Corp. in Farmington Hills, MI. His focus was on groundwater contamination; groundwater modeling; air modeling, compliance, and permitting issues in the U.S. and Canada; and statistical analysis. Prior to joining Dragun Corp. in 1995, he was a reservoir engineer and a lecturer. Chekiri received his BSc in applied mathematics (Univ. of Algiers, 1974), MSc in petroleum engineering (Colorado School of Mines, 1978), and PhD in environmental engineering (Univ. of Windsor, 1996). His doctoral research involved the use of isotopes to evaluate fractured clay integrity. Chekiri is a professional engineer in both Michigan and Ontario.