9 research outputs found
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A Hydrologic monitoring program to detect potential impacts of geothermal development in Long Valley caldera, California
Long Valley caldera is a tectonically active area in east-central California that contains a high-temperature geothermal system currently being explored and developed for electric power production. Concerns expressed by public agencies and private citizens over the potential impacts of geothermal development on thermal springs at the Hot Creek Fish Hatchery and Hot Creek gorge have resulted in the establishment of a Hydrologic Advisory Committee. The committee includes representatives from development projects and regulatory agencies. Its role is to formulate and oversee a hydrologic monitoring program capable of detecting such impacts before they become significant. The advisory committee and the monitoring program provide effective mechanisms with which to proceed with geothermal development in areas such as Long Valley, where the level of environmental risk cannot be determined a-priori because the relevant geo-hydrologic parameters are not adequately delineated
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Numerical Code Comparison Project - A Necessary Step Towards Confidence in Geothermal Reservoir Simulators
A necessary first step in resolving differences and in evaluating the usefulness of numerical simulators for geothermal reservoir analysis is the comparison of simulator results for a set of well-specified problems involving processes applicable in reservoir analysis. Under the direction of DOE'S Geothermal Reservoir Engineering Management Program (GREMP), a set of six test problems has been developed in an attempt to meet this need. The problem set covers a range of reservoir situations including single- and two-phase flow under 1, 2, and 3 dimensional conditions. Each problem has been test run to insure that the parameter specifications will yield workable solutions, and in several cases analytical solutions are available for comparison. Brief descriptions of the problems are given in each problem, the desired grid and time-step sizes were specified to minimize differences in results due to numerical discretization
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Hot Spring Monitoring at Lassen Volcanic National Park, California 1983-1985
Data collected on several occasions between 1983 and 1985 as part of a hydrologic monitoring program by the U.S. Geological Survey permit preliminary estimation of the natural variability in the discharge characteristics of hydrothermal features in Lassen Volcanic National Park and the Lassen KGRA in northern California. The total rate of discharge of high-chloride hot springs along Mill Creek and Canyon Creek in the Lassen KGRA has averaged 20.9 {+-} 1.7 L/s, based on seven measurements of the flux of chloride in these streams. Measured chloride flux does not appear to increase with streamflow during the spring-summer snowmelt period, as observed at Yellowstone and Long Valley Caldera. The corresponding fluxes of arsenic in Mill Creek and Canyon Creek decrease within distances of about 2 km downstream from the hot springs by approximately 30%, most likely due to chemical absorption on streambed sediments. Within Lassen Volcanic National Park, measurements of sulfate flux in streams draining steam-heated thermal features at Sulphur Works and Bumpass Hell have averaged 7.5 {+-} 1.0 and 4.0 {+-} 1.5 g/s, respectively. Calculated rates of steam upflow containing, dissolved H{sub 2}S to supply these sulfate fluxes are 1.8 kg/s at Sulphur Works and 1.0 kg/s at Bumpass Hell
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Numerical Simulations of the Hydrothermal System at Lassen Volcanic National Park
The hydrothermal system in the vicinity of Lassen Volcanic National Park contains a central region of fluid upflow in which steam and liquid phases separate, with steam rising through a parasitic vapor-dominated zone and liquid flowing laterally toward areas of hot spring discharge south of the Park. A simplified numerical model was used to simulate the 10,000-20,000 year evolution of this system and to show that under certain circumstances fluid withdrawal from hot-water reservoirs south of the Park could significantly alter the discharge of steam from thermal areas within the Park
Potential effects of the Hawaii Geothermal Project on ground-water resources on the island of Hawaii
"In 1990, the State of Hawaii proposed the Hawaii Geothermal Project for the development of as much as 500 MW of electric power from the geothermal system in the East Rift Zone of Kilauea Volcano. This report uses data from 31 wells and 8 springs to describe the properties of the ground-water system in and adjacent to the East Rift Zone. Potential effects of this project on ground-water resources are also discussed. Data show differences in ground-water chemistry and heads within the study area that appear to be related to mixing of waters of different origins and ground-water impoundment by volcanic dikes. East of Pahoa, the ground-water system within the rift is highly transmissive and receives abundant recharge from precipitation; therefore, the pumping of freshwater to support geothermal development in that part of the rift zone would have a minimal effect on ground-water levels. To the southwest of Pahoa, dike impoundment reduces the transmissivity of the ground-water system to such an extent that wells might not be capable of supplying sufficient fresh water to support geothermal operations. Contamination of ground-water resources by accidental release of geothermal fluids into shallow aquifers is possible because of corrosive conditions in the geothermal wells, potential well blowouts, and high ground-water velocities in parts of the region. Hydrologic monitoring of water level, temperature, and chemistry in observation wells should continue throughout development of geothermal resources for the Hawaii Geothermal Project for early detection of leakage and migration of geothermal fluids within the groundwater system."Includes bibliographical references (p. 33-35)
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Tapping the Earth's Natural Heat
This is a very good survey of geothermal energy resources and technologies, particularly from a broad geological point of view. There are many maps and diagrams of some of the most interesting North American geothermal resource sites and prospects. Overall, this provides a very good introduction to the diversity of origins and configurations of useful geothermal energy deposits. (DJE 2005