Principal Civil and Environmental Engineer
Dr. Hinchee is a recognized expert in remediation. Over his 40 year environmental career, he has developed and applied assessment and remedial technologies, at thousands of sites throughout North America, Europe, Latin America and the Middle East. He has also designed, implemented and/or evaluated hundreds of water, sediment, and soil treatment systems. He was responsible for the design and implementation of field demonstration processes such as soil vacuum extraction, air sparging, landfarming, in situ bioremediation, biopiles, and in-place stabilization systems. He was the Technical Director overseeing characterization and remediation of the Trecate oil well blowout near Milan, Italy. At the time largest soil cleanup in European history. Additionally Dr Hinchee worked in Saudi Arabia and Kuwait developing remedial approaches for dealing with the hundreds of square kilometers of land and shoreline contaminated with oil, the largest oil spill in history, as a result of Iraqi actions in the 1991 Gulf War. He has authored, co-authored, edited, and co-edited numerous publications including more than 25 books and was the founding editor of the Journal of Bioremediation. Dr. Hinchee organized and chaired the International Symposia on In Situ and On-Site Bioremediation, held in San Diego (1991, 1993, and 1995), and maintains continued involvement. In addition to technical work, Dr. Hinchee has testified to the U.S. Congress, the United Nations Compensation Commission and served as an expert witness in a variety of cases.
FLASH POSTER PRESENTER - Emerging Contaminants: Tick Tock
SVE for 1,4-Dioxane, What Works
Vadose zone 1,4-dioxane contamination can be an ongoing source to groundwater and recent work has shown soil vapor extraction (SVE) to be an effective means of treatment. This paper will present the results of an ESTCP-funded project in which SVE using heated air injection and focused vapor flow was demonstrated at a site on the former McClellan Air Force Base near Sacramento California. Air was injected and extracted at much higher than normal rates for approximately 12 months, resulting in exchange of approximately 20,000 pore volumes, roughly 10 to 100 times more than used for conventional SVE. Following the SVE operation extensive soil sampling demonstrated greater than 95% 1,4-dioxane removal.
Depth to groundwater was approximately 100 feet and initial sampling showed the highest 1,4-dioxane concentrations were located approximately 38 to 68 feet below land surface. Site stratigraphy was predominately silt and silty sands with some clays and occasional thin and discontinuous fine sand layers. The SVE system consisted of one extraction and four injection wells all screened from approximately 38 to 68 feet below land surface. Air was extracted at a nominal rate of 100 cfm for approximately 1 year. Air was injected at a nominal temperature a little above 100 C. The volume of soil treated was approximately 12,000 cubic feet.
The system was partially successful in heating and drying the soil, which allowed for the evaluation of both heated and non-heated treatment. Surprisingly the heating did not appear to incrementally improve treatment. Based on this work it is clear that SVE alone can be successful in the remediation of 1,4-dioxane contaminated soil, so long as the SVE system runs at higher than typical air exchange rates. This could be accomplished using air injection in combination with extraction, using higher air flow rates, or simply operating SVE systems for a longer time. Many, if not most 1,4-dioxane contaminated soil sites have been subject to SVE to remove the more volatile chlorinated solvents. These existing systems may simply be upgraded or operated for a longer time to treat the 1,4-dioxane.