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Title: Water quality monitoring at the Hoe Creek test site: review and preliminary conclusions

Abstract

Post-burn monitoring of the ground water near to the Hoe creek underground coal gasification site showed that a broad range of gasification products had been introduced into the water system. Although many of these contaminants were eventually absorbed by the surrounding coal, some chemicals continued to appear in the water in concentrations higher than pre-test levels for several years after gasification. Possible mechanisms by which the contaminants entered the ground water include: (1) leakage of pyrolysis products; (2) post-burn leaching of coal ash and overburden rubble by returning ground water; and (3) dissolution of minerals outside the cavity by the CO/SUB/2 generated during gasification.

Authors:
Publication Date:
OSTI Identifier:
6843735
Alternate Identifier(s):
OSTI ID: 6843735
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIChE Symp. Ser.; (United States); Journal Volume: 79:226
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; 54 ENVIRONMENTAL SCIENCES; GROUND WATER; MONITORING; WATER POLLUTION; IN-SITU GASIFICATION; ENVIRONMENTAL EFFECTS; ASHES; CHEMICAL EFFLUENTS; COAL GASIFICATION; CONTAMINATION; DISSOLUTION; LEACHING; LEAKS; PYROLYSIS PRODUCTS; WATER QUALITY; ENVIRONMENTAL QUALITY; GASIFICATION; HYDROGEN COMPOUNDS; IN-SITU PROCESSING; OXYGEN COMPOUNDS; POLLUTION; PROCESSING; RESIDUES; SEPARATION PROCESSES; THERMOCHEMICAL PROCESSES; WATER 010900* -- Coal, Lignite, & Peat-- Environmental Aspects; 010404 -- Coal, Lignite, & Peat-- Gasification; 520200 -- Environment, Aquatic-- Chemicals Monitoring & Transport-- (-1989)

Citation Formats

Wang, F.T.. Water quality monitoring at the Hoe Creek test site: review and preliminary conclusions. United States: N. p., 1983. Web.
Wang, F.T.. Water quality monitoring at the Hoe Creek test site: review and preliminary conclusions. United States.
Wang, F.T.. Sat . "Water quality monitoring at the Hoe Creek test site: review and preliminary conclusions". United States. doi:.
@article{osti_6843735,
title = {Water quality monitoring at the Hoe Creek test site: review and preliminary conclusions},
author = {Wang, F.T.},
abstractNote = {Post-burn monitoring of the ground water near to the Hoe creek underground coal gasification site showed that a broad range of gasification products had been introduced into the water system. Although many of these contaminants were eventually absorbed by the surrounding coal, some chemicals continued to appear in the water in concentrations higher than pre-test levels for several years after gasification. Possible mechanisms by which the contaminants entered the ground water include: (1) leakage of pyrolysis products; (2) post-burn leaching of coal ash and overburden rubble by returning ground water; and (3) dissolution of minerals outside the cavity by the CO/SUB/2 generated during gasification.},
doi = {},
journal = {AIChE Symp. Ser.; (United States)},
number = ,
volume = 79:226,
place = {United States},
year = {Sat Jan 01 00:00:00 EST 1983},
month = {Sat Jan 01 00:00:00 EST 1983}
}
  • It has been shown that underground coal gasification (UCG) may introduce a broad range of residual products into the groundwater of a coal aquifer. Sorption of many contaminants by the coal itself is an important factor in restricting the migration of these contaminants in the groundwater. However, our field studies at the Lawrence Livermore National Laboratory (LLNL) Hoe Creek site in northeastern Wyoming have shown that sorption of organic compounds by coal is not as effective as expected, perhaps because the coal surface area is limited. Furthermore, if severe roof collapse has taken place during gasification, non-coal aquifers located abovemore » the gasified coal seam may become interconnected with the cavity. Contaminants may enter these non-coal aquifers, in which sorption is even less effective. The Hoe Creek II and III experiments have enabled us to study the contamination of a sand aquifer located above a gasified coal seam in a hydrological recharge area. The preliminary results indicate that the water in the overlying sand aquifer is much less contaminated with organic compounds than that in the gasified« less
  • It has been shown that underground coal gasification (UCG) may introduce a broad range of residual gasification products into the groundwater of a coal aquifer. Sorption of many contaminants by the coal itself is an important factor in restricting the migration of these contaminants in the ground water. However, field studies, conducted at Lawrence Livermore National Laboratory's Hoe Creek site, have shown that sorption of organic compounds by coal is not as effective as expected, perhaps because the coal surface area is limited. Furthermore, if severe roof collapse has taken place during gasification, non-coal aquifers located above the gasified coalmore » seam may be interconnected with the coal aquifer, and contaminants may enter these non-coal aquifers, in which sorption is even less effective. The Hoe Creek II and III experiments have provided opportunities to study the contamination of a sand aquifer located above a gasified coal seam in a hydrological recharge area. Preliminary results indicate that the water in the overlying sand aquifer is much less contaminated with organic compounds than the water in the gasified coal aquifer. In conducting these field investigations, valuable lessons ere learned concerning groundwater monitoring. A suggested monitoring strategy is discussed.« less
  • It has been shown that underground coal gasification (UCG) may introduce a broad range of residual gasification products into the groundwater of a coal aquifer. Sorption of many contaminants by the coal itself is an important factor in restricting the migration of these contaminants in the groundwater. However, our field studies at the Lawrence Livermore National Laboratory (LLNL) Hoe Creek site in northeastern Wyoming have shown that sorption of organic compounds by coal is not as effective as expected, perhaps because the coal surface area is limited. Furthermore, if severe roof collapse has taken place during gasification, non-coal aquifers locatedmore » above the gasified coal seam may be interconnected with the coal aquifer. Contaminants may enter these non-coal aquifers, in which sorption is even less effective. The Hoe Creek II and III experiments have enabled us to study the contamination of a sand aquifer located above a gasified coal seam in a hydrological recharge area. Our preliminary results indicate that the water in the overlying sand aquifer is much less contaminated with organic compounds than that in the gasified coal aquifer. In conducting these field investigations, we have also learned valuable lessons concerning a strategy for groundwater monitoring. 21 figures.« less
  • We have monitored groundwater quality changes in approximately 60 wells constructed near the 3 underground coal gasification (UCG) experiments carried out at our Hoe Creek site in northeastern Wyoming. A broad range of residual gasification products are introduced into the groundwater system as a result of the UCG process. These groundwater contaminants may be of environmental significance if they find their way, in sufficient concentrations, into surface waters or aquifers from which water is extracted for drinking or agricultural purposes. In seeking to identify effective control technologies or mitigation measures, we have found it important to investigate the mechanisms responsiblemore » for the formation and dispersal of the contaminants. For example, an important mechanism for the production of organic contaminants may be pyrolysis reactions along the surfaces of cracks through which hot product gases escape from the cavity during gasification. As gasification continues, these pyrolysis products will be distilled further out in the surrounding coal and deposited on the coal surfaces. Other mechanisms that are believed to be important are post-burn pyrolysis as a result of residual cavity heat and the liberation of minerals from the coal by the action of dissolved CO/sub 2/.« less
  • In three underground coal gasification experiments at the Hoe Creek site near Gillette, WY, LLNL applied three different linking methods: explosive fracture, reverse burning, and directional drilling. Air was injected in all three experiments; a steam/oxygen mixture, during 2 days of the second and most of the third experiment. Comparison of results show that the type of linking method did not influence gas quality. The heat of combustion of the product gas was higher with steam/oxygen injection, mainly because of reduced inert diluent. Gas quality was generally independent of other operating parameters but declined from its initial value over amore » period of time because of heat loss to the wet overburden and extensive roof collapse in the second and third experiments.« less