6 research outputs found

    Hydrogeologic Conditions Around Deep Aeration Lagoons at the Bardstown Wastewater Treatment Plant

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    The hydrogeologic conditions around the Bardstown Sewage Treatment Plant were studied from August 1996 through December 1997. Hydraulic and geochemical data were collected from eight monitoring wells and four surface-water monitoring sites on the plant property. There is a large hydraulic gradient between the lagoons at the plant and the surrounding stream, Town Creek. Initial water-level measurements in wells surrounding the site suggest no major leakage from the lagoons, however. Neither flowing artesian conditions nor unusually high water levels were observed in any of the wells. Water-level measurements collected by data loggers showed that shallow wells responded quickly to recharge, whereas bedrock wells were relatively unresponsive throughout most of the observation period. Slug tests indicate that the hydraulic conductivities of the unconsolidated material monitored by the shallow wells are several orders of magnitude greater than for the underlying bedrock. Surface-water flow measurements indicate that Town Creek is a losing stream adjacent to the lagoons. This conclusion is supported by hydraulic data from the monitoring wells. These data suggest that it is unlikely the lagoons are leaking significantly into Town Creek. Town Creek appears to become a gaining stream along its lowest reaches on the northwestern side of the plant property. Interpretation of chloride, bromide, fluoride, and major-ion chemistry data indicates that the water chemistry in the shallow wells is not affected significantly by the lagoons. Well-water chemistry is influenced by Town Creek, which recharges the shallow alluvial sediments during high flow. All metal concentrations appear to be below primary and secondary maximum contaminant levels (MCL\u27s) in both the lagoons and the stream water. The only metals for which the MCL was exceeded at the site are iron and manganese; concentrations were relatively high in the shallow ground-water monitoring wells. Concentrations of these metals are commonly elevated in ground water derived from shallow, alluvial sediments in this physiographic region, however. These data suggest that the lagoons are having a minimal impact, if any, on the quality of ground water around the lagoons. The results from a one-time sampling for bacteria indicate that the total coliform in the monitoring wells ranged from 10 to 1,920 colonies per 100 ml (col/100 ml). Analysis for E. coli bacteria showed that only one well, BT30, contained measurable counts (10 col/100 ml). The presence of E. coli in this well is inconsistent with other parameters that would indicate contamination from the lagoons, however; their presence may represent contamination during sampling. The data from this investigation, as well as previous studies, indicate that the lagoons provide efficient primary water treatment without causing significant ground-water contamination. Moreover, the design and engineering used for the Bardstown plant may provide a model for cost-effective, efficient primary water-treatment systems capable of long-term operation without affecting the local ground-water system. Lagoons in other physiographic and geologic settings should be studied to determine the effect of large lagoons throughout the state. This is especially pertinent now, because public and regulatory agencies have expressed great interest in lagoon technology for managing wastes from large-scale livestock operations

    Effects of Longwall Mining on Hydrogeology, Leslie County, Kentucky Part 3: Post-Mining Conditions

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    The effects of longwall coal mining on hydrology in the Eastern Kentucky Coal Field have been investigated since 1991. The study area is in the Edd Fork watershed in southern Leslie County, over Shamrock Coal Company\u27s Beech Fork Mine. Longwall panels approximately 700 ft wide are separated by three-entry gateways that are approximately 200 ft wide. The mine is operated in the Fire Clay (Hazard No. 4) coal; overburden thickness ranges from 300 to 800 ft. Mining began in panel 1 in September 1991 and concluded with panel 8 in September 1994. Long-term monitoring consisting of a network of piezometers and time-domain reflectometry (TDR) cables previously installed over panel 7, in conjunction with a continuously recording rain gage and flume, began after the completion of mining. Two new core holes were drilled over panel 7 approximately 1 year after mining ceased in panel 8 to determine depth of collapse and hydraulic conductivity of strata. Water levels were measured in two new monitoring wells installed after mining to complement the 11 piezometers installed prior to mining that were still functioning. Precipitation was measured through July 1996, and streamflow was measured in Edd Fork on a monthly basis using a cross-section gaging method. Physical failure of piezometers, core drilling, and the movement of air into deeper piezometers after mining indicate that extensive fracturing occurred to a height of 450 ft above the mine, which is approximately 60 times the extracted coal-seam thickness. Hydraulic conductivity values determined from pressure-injection tests were 10 to 100 times greater after mining than before mining; many values were in the range of 10-2 to 10-4 ft/min for all lithologies. At a minimum, a zone of rock approximately 200 ft above the mined coal was dewatered beneath Edd Fork. Ground-water levels in ridgetop piezometers fluctuated slightly more after mining than they did before, which indicates that the upper part of the ridge is more hydraulically connected to surface recharge from precipitation since mining took place. The existence of ground water in the shallow ridgetop piezometers suggests that an underlying aquitard zone developed during mine collapse, which retards the downward movement of shallow ground water to the mined-out area. Water level declined in a sandstone unit approximately 300 ft above the mine after mining, but recovered within a year. This indicates that the underlying regional aquitard still retards downward ground-water movement, despite the hydraulic conductivity of the unit increasing 100 times after mining. Edd Fork, approximately 375 ft above the mine in panel 7, resumed surface flow 2 months after completion of mining; however, flow diminishes downstream at about the centerline of panel 8. Mining is still active in other areas of the mine, and mechanical dewatering activities will most likely keep water levels in the deep zones artificially depressed in the study area until mining is completed and dewatering activities cease

    Effects of Longwall Mining on Hydrology, Leslie County, Kentucky Part 2: During-Mining Conditions

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    The effects of longwall coal mining on hydrology in the Eastern Kentucky Coal Field are being investigated. The study area is in the Edd Fork watershed in southern Leslie County, over Shamrock Coal Company\u27s Beech Fork Mine. Longwall panels approximately 700 ft wide are separated by three-entry gateways that are approximately 200 ft wide. The mine is operated in the Fire Clay (Hazard No. 4) coal; overburden thickness ranges from 300 to 800 ft. Mining began in panel 1 in September 1991 and concluded with panel 8 in September 1994. Long-term monitoring consisting of a network of piezometers and time-domain reflectometry (TDR) cables previously installed over panel 7, in conjunction with a continuously recording rain gage and flume, is continuing after the completion of mining. Mining in panel 5 affected water levels in three of 24 piezometers installed over panel 7; the level went down in one piezometer and rose in two. Mining in panel 6 affected 16 of 24 piezometers; the level went down in 11 piezometers and rose in five. Mining in panel 7 affected water levels in 20 of 24 piezometers. Different water-level responses were recorded as the mine approached and passed by the instrumental sites. Thirteen piezometers failed as a result of undermining. These piezometers penetrated the zone of deep fracturing that extends upward approximately 450 ft (or 60 times greater than the mined thickness) above the mine. Only one piezometer showed a net increase in water level as a result of mining. Mining-induced surface fractures, observed along roads in the watershed, were generally parallel to the slope of the land surface or mining direction and probably contributed to ground-water recharge. The surface stream was unaffected until it was undermined by panel 8; then the stream went dry. TDR cables in the Hazard coal zone were deformed as mining passed by on the adjacent panel. Water levels in piezometers in the Hazard coal zone declined at the same time. TDR cables broke completely twice. The deepest complete break was in the Hazard coal zone and occurred when the active mine face was approaching, but still approximately 1,000 ft away from, the affected cable in panel 7. This corresponds to an angle of influence of 60 to 70°. Rock broke in the shallow subsurface (less than 50 ft deep) when the cable was directly undermined. Water-level responses in piezometers adjacent to mining are related to the complex flow system, rather than a defined angle of hydrologic influence. Coal beds and other conductive strata transmit water-level responses as far away as 1,450 ft, whereas nonconductive strata transmit little water-level change at closer distances. The water-level responses observed in this study support existing subsidence models. Piezometers in the zone of intensive fracturing failed as a result of rock breakage. An aquiclude zone developed in the ridge. The integrity of strata and piezometers was generally maintained. The most variable effects were observed in the zone of surface fracturing, within 50 ft of the surface

    A Bibliography of Dissertations Related to Illinois History, 1996-2011

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