John Colvin

Updated methods for assessing the impacts of nearby gas drilling and production on neighborhood air quality and human health

ABSTRACT An explosive growth in natural gas production within the last decade has fueled concern over the public health impacts of air pollutant emissions from oil and gas sites in the Barnett and Eagle Ford shale regions of Texas. Commonly acknowledged sources of uncertainty are the lack of sustained monitoring of ambient concentrations of pollutants associated with gas mining, poor quantification of their emissions, and inability to correlate health symptoms with specific emission events. These uncertainties are best addressed not by conventional monitoring and modeling technology, but by increasingly available advanced techniques for real-time mobile monitoring, microscale modeling and source attribution, and real-time broadcasting of air quality and human health data over the World Wide Web. The combination of contemporary scientific and social media approaches can be used to develop a strategy to detect and quantify emission events from oil and gas facilities, alert nearby residents of these events, and collect associated human health data, all in real time or near-real time. The various technical elements of this strategy are demonstrated based on the results of past, current, and planned future monitoring studies in the Barnett and Eagle Ford shale regions. Implications: Resources should not be invested in expanding the conventional air quality monitoring network in the vicinity of oil and gas exploration and production sites. Rather, more contemporary monitoring and data analysis techniques should take the place of older methods to better protect the health of nearby residents and maintain the integrity of the surrounding environment.

DESIGN AND TESTING OF A PULSE TUBE BASED COOLING SYSTEM FOR HIGH PURITY GERMANIUM DETECTORS

A cooling package based on a new type of production cryocooler was designed and tested at the Technology Development Laboratory (TDL) of the Houston Advanced Research Center (HARC) in collaboration with the company Kelvin International. The prototype is based on an Iwatani CryoMini® Pulse Tube Cryocooler provided by Kelvin International. The CryoMini cryocooler was integrated with an EG&G Pop-Top High Purity Germanium (HPGe) detector within a TDL designed cooling package. One of the key features of this new type of cryocooler is the small size of its cold head allowing for the combination of the cooling package prototype and an EG&G Pop-Top detector to fit within a cylindrical volume with a diameter slightly larger than 3 inches and a length of less than 2 1/2 feet long. The compact design of the cryocooler is attractive for environmental surveys, shallow hole investigations, and other applications that require long uninterrupted operating time, minimal space and ease of operation. The Cooling package temperature histories were recorded during operation, and gamma ray spectra were acquired with the prototype. A steady state temperature of 78 K was achieved in the Pop-Top capsule. This temperature is well within the operating range of a standard HPGe Pop-Top detector and provides a comfortable margin to convert the prototype into a more rugged field device. The energy resolution of an HPGe detector is compared for spectra acquired with the prototype and with a standard liquid nitrogen dewar for calibration sources and Naturally Occurring Radioactive Material (NORM) samples. The energy resolution of the prototype was measured at 2.08 keV for the 1.332 MeV line of a Cobalt-60 gamma ray source. Although somewhat higher than the resolution measured for the same detector cooled with a liquid nitrogen cryostat (1.73 keV) the measured energy resolution is within the warranted range for the HPGe detector used in this study.