Aaron Orechwa

Environmental Engineer, Tetra Tech

Mr. Orechwa has 15 years of experience as an environmental engineer and radiation scientist. During this time, he has developed expertise across diverse segment strategies in a variety of fields including mine remediation, site characterization, health physics, project management, and water resources engineering. He specializes in environmental monitoring and radiological surveillance for the characterization of remote abandoned mining sites, particularly sites located on tribal lands. To date, at more than 120 radiologically impacted sites in 15 states and two countries, Mr. Orechwa has led, managed, and/or performed field investigations of abandoned uranium mines, uranium mills, ore transfer stations, hazardous waste sites, oil and gas facilities, military sites, and sites related to nuclear testing and nuclear power facilities. He has also conducted and supported engineering related activities and field services work at non-radiological sites across the country, including legacy metal and gold mines.

His expertise spans radiological site characterization, statistical analysis of environmental systems, regional background study design, geographic information system (GIS) geospatial techniques for hydrological and erosion modeling, geostatistical analysis, exploratory data analysis, innovative sampling techniques, remote sensing with unmanned aerial vehicles (UAVs) for conducting radiological surveillance, probabilistic data analysis, and technical report writing. Mr. Orechwa has managed projects as large as $7 million and he provides consulting and oversight services to a number of commercial clients, law firms, and government agencies—including the U.S. Forest Service (USFS) and the U.S Environmental Protection Agency (EPA).

He currently serves as technical lead and mine rock radiation investigation expert under the RAES contract for EPA Region 9. Mr. Orechwa is technical lead for 53 abandoned uranium mines and mills now undergoing assessment and or cleanup and he is also providing oversight for EPA on another 180 uranium mines in the Navajo Nation. Finally, Mr. Orechwa currently supports all three uranium mines listed on the National Priorities List (NPL) as a radiological specialist and environmental engineer (Jackpile Paguate, Midnite Mine, White King/Lucky Lass).

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UAV – A Complementary Approach to Conventional Methods

Focus is on an unmanned aerial vehicle (UAV) system that conducts aerial radiological surveys of high precision that autonomously follow terrain. Current conventional radiological survey methods applied at abandoned uranium mines throughout the southwestern United States may be non-repeatable, are hazardous to the operator, and often involve a level of user error rendering results difficult to accept for final status surveys at decommissioned or remediated sites. The presented system follows an alternative, yet complementary approach to conventional methods, and was developed to alleviate those concerns by providing efficient, repeatable, and spatially accurate results from aerial-based radiological surveys. The UAV was equipped with real-time kinematic GPS and carried a 2-in sodium iodide thallium-activated crystal with lightweight datalogger. This presentation summarizes findings from a pilot study at an abandoned uranium mine where both conventional ground-based and unmanned aerial vehicle-based scanning techniques were performed. More than 12 missions occurred at different times over a 2-month period and several flight altitudes between 1 and 10 meters above ground were evaluated at varying speed and width. This presentation explores relationships of these controllable flight parameters on radiation mapping, assesses comparability and repeatability of each survey method, and evaluates attenuation from operator during ground-based surveys. Other aspects of the survey included a diurnal radon evaluation, normalization to ionization chamber, and laboratory analysis of radionuclides. Additionally, the study examined several issues such as comparability, cost, efficiency, and data quality to answer principal study questions and address several objectives. Findings verified the extreme promise of this technology for immediate application at a definitive level at abandoned uranium mines, decommissioned radiological facilities, or sites affected by TENORM material.