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1.
《Ground Water Monitoring & Remediation》1985,5(1):51-57
The possible mine will remove a gently, less than 50 feet per mile, westerly dipping Springfield coal from an area covered by glacial till and some channel sands and gravel. The area is flat, with less than 20 feet of relief in a square mile. The channel sands and gravels, the till and the bedrock are capable of yielding ground water at 5 to 75,3 to 10, and 1 to 10 gallons per minute (gpm), respectively. The ground water in the drift and the shallow bedrock is calcium-bicarbonate type, contrasting with the sodium-bicarbonate type in the deep bedrock. The surface mine will feature selective handling of overburden. The probable hydrologic consequences of the mine will be 1) a short-term, areally limited dewatering, 2) an increase in dissolved solids, 3) a change in ground water chemistry in some areas to a calcium-bicarbonate sulfate water, 4) an increase in ground water storage, and 5) a new integrated surface water system. The proposed ground water monitoring system will include seven monitoring wells in the glacial material and one in the bedrock. The primary effort in ground water monitoring to the west of the mine will be to detect changes in the quality of the ground water, whereas to the east, changes in both quality and quantity will need to be monitored intensively. 相似文献
2.
简单论述了横波的基本特点,指出在松散层勘探中,横波勘探的优势主要在于探测精度高且不受饱水度的影响.因此,可以选择地震横波勘探进行第四纪松散层层序划分及厚度探测.并以广州市城市地质调查项目为例,介绍了地震横波勘探在浅层地层勘测中的数据采集方法,分析了地质解释依据,并结合波速测井方法对地层层面进行了划分.分析结果表明了多数岩土层与反射界面有较好的对应关系,用地震横波勘探结合波速测井进行第四纪松散层层序划分及厚度探测是可行的. 相似文献
3.
Near-surface seismic refraction and surface wave data were collected at a site to determine the feasibility and limitations of using these seismic methods to detect and localize a shallow tunnel in unconsolidated sediments. Data sets were collected both before and after the construction of the tunnel. We were able to detect the air-filled cavity using multichannel analysis of surface waves. The refraction tomography results showed the tunnel location in the raypath coverage plots, but only small velocity variations were observed. In tandem the two methods would reduce false positives, but individually the false alarm rate would likely be high due to non-uniqueness of the results. In this geologic setting, these methods are not the best choice of geophysical methods to detect clandestine tunnels and should be combined with other geophysical techniques to improve and constrain interpretations. 相似文献
4.
5.
Thomas J. Mack 《Ground Water Monitoring & Remediation》1993,13(1):107-114
Two borehole geophysical methods—electromagnetic induction and natural gamma radiation logs—were used to vertically delineate landfill leachate plumes in a glacial aquifer. Geophysical logs of monitoring wells near two land-fills in a glacial aquifer in west-central Vermont show that borehole geophysical methods can aid in interpretation of geologic logs and placement of monitoring well screens to sample landfill leachate plumes.
Zones of high electrical conductance were delineated from the electromagnetic log in wells near two landfills. Some of these zones were found to correlate with silt and clay units on the basis of drilling and gamma logs. Monitoring wells were screened specifically in zones of high electrical conductivity that did not correlate to a silt or clay unit. Zones of high electrical conductivity that did not correlate to a silt or clay unit were caused by the presence of ground water with a high specific conductance, generally from 1000 to 2370 μS/cm (microsiemens per centimeter at 25 degrees Celsius). Ambient ground water in the study area has a specific conductance of approximately 200 to 400 μS/cm. Landfill leachate plumes were found to be approximately 5 to 20 feet thick and to be near the water table surface. 相似文献
Zones of high electrical conductance were delineated from the electromagnetic log in wells near two landfills. Some of these zones were found to correlate with silt and clay units on the basis of drilling and gamma logs. Monitoring wells were screened specifically in zones of high electrical conductivity that did not correlate to a silt or clay unit. Zones of high electrical conductivity that did not correlate to a silt or clay unit were caused by the presence of ground water with a high specific conductance, generally from 1000 to 2370 μS/cm (microsiemens per centimeter at 25 degrees Celsius). Ambient ground water in the study area has a specific conductance of approximately 200 to 400 μS/cm. Landfill leachate plumes were found to be approximately 5 to 20 feet thick and to be near the water table surface. 相似文献
6.
Suzanne Lesage Richard E. Jackson Mark Priddle Paul Beck Ken G. Raven 《Ground Water Monitoring & Remediation》1991,11(1):151-159
The objective of this study was to assess the possible impact of deep well disposal operations, conducted between 1958 and 1974, on the ground water quality in a shallow fresh water aquifer beneath Sarnia, Ontario, Canada. Because of the breakout of formation fluids in Sarnia and Port Huron, Michigan, in the early 1970s, it had been hypothesized that liquid waste from the disposal zone in bedrock had leaked through numerous abandoned oil, gas, and salt wells in the area up to the shallow fresh water aquifer and from there to the surface.
A monitoring well network of 29 5cm (2 inch) diameter piezometers was established in the thin sand and shale aquifer system, which exists between 30 and 70m (100 and 230 feet) below ground surface. In addition, a 300m (1000 foot) deep borehole was drilled and instrumented with a Westbay multilevel casing, which permitted sampling of the disposal zone.
Ground water samples from the shallow monitoring wells and the Westbay multilevel casing were analyzed for volatiles by GC/MS. Those volatile aromatics that were conspicuously present in the deep disposal zone, e.g., ethyl toluenes and trimethyl benzene, were not detected in the shallow monitoring wells. Thus, if contaminants from the disposal zone did indeed migrate to the shallow aquifer, contamination was not widespread and probably consisted mostly of displaced chloride-rich formation waters. 相似文献
A monitoring well network of 29 5cm (2 inch) diameter piezometers was established in the thin sand and shale aquifer system, which exists between 30 and 70m (100 and 230 feet) below ground surface. In addition, a 300m (1000 foot) deep borehole was drilled and instrumented with a Westbay multilevel casing, which permitted sampling of the disposal zone.
Ground water samples from the shallow monitoring wells and the Westbay multilevel casing were analyzed for volatiles by GC/MS. Those volatile aromatics that were conspicuously present in the deep disposal zone, e.g., ethyl toluenes and trimethyl benzene, were not detected in the shallow monitoring wells. Thus, if contaminants from the disposal zone did indeed migrate to the shallow aquifer, contamination was not widespread and probably consisted mostly of displaced chloride-rich formation waters. 相似文献
7.
Surface geophysical surveys provide an effective way to image the subsurface and the ground water zone without a large number of observation wells. DC resistivity sounding generally identifies the subsurface formations-the aquifer zone as well as the formations saturated with saline/brackish water. However, the method has serious ambiguities in distinguishing the geological formations of similar resistivities such as saline sand and saline clay, or water quality such as fresh or saline, in a low resistivity formation. In order to minimize the ambiguity and ascertain the efficacy of data integration techniques in ground water and saline contamination studies, a combined geophysical survey and periodic chemical analysis of ground water were carried out employing DC resistivity profiling, resistivity sounding, and shallow seismic refraction methods. By constraining resistivity interpretation with inputs from seismic refraction and chemical analysis, the data integration study proved to be a powerful method for identification of the subsurface formations, ground water zones, the subsurface saline/brackish water zones, and the probable mode and cause of saline water intrusion in an inland aquifer. A case study presented here illustrates these principles. Resistivity sounding alone had earlier failed to identify the different formations in the saline environment. Data integration and resistivity interpretation constrained by water quality analysis led to a new concept of minimum resistivity for ground water-bearing zones, which is the optimum value of resistivity of a subsurface formation in an area below which ground water contained in it is saline/brackish and unsuitable for drinking. 相似文献
8.
A new multilevel ground water monitoring system has been developed that uses custom-extruded flexible 1.6-inch (4.1 cm) outside-diameter (O.D.) multichannel HOPE tubing (referred to as Continuous Multichannel Tubing or CMT) to monitor as many as seven discrete zones within a single borehole in either unconsolidated sediments or bedrock. Prior to inserting the tubing in the borehole, ports are created that allow ground water to enter six outer pie-shaped channels (nominal diameter = 0.5 inch [1.3 cm]) and a central hexagonal center channel (nominal diameter = 0.4 inch [1 cm]) at different depths, facilitating the measurement of depth-discrete piezometric heads and the collection of depth-discrete ground water samples. Sand packs and annular seals between the various monitored zones can be installed using conventional tremie methods. Alternatively, bentonite packers and prepacked sand packs have been developed that are attached to the tubing at the ground surface, facilitating precise positioning of annular seals and sand packs. Inflatable rubber packers for permanent or temporary installations in bedrock aquifers are currently undergoing site trials. Hydraulic heads are measured with conventional water-level meters or electronic pressure transducers to generate vertical profiles of hydraulic head. Ground water samples are collected using peristaltic pumps, small-diameter bailers, inertial lift pumps, or small-diameter canister samplers. For monitoring hydrophobic organic compounds, the CMT tubing is susceptible to both positive and negative biases caused by sorption, desorption, and diffusion. These biases can be minimized by: (1) purging the channels prior to sampling, (2) collecting samples from separate 0.25-inch (0.64 cm) O.D. Teflon sampling tubing inserted to the bottom of each sampling channel, or (3) collecting the samples downhole using sampling devices positioned next to the intake ports. More than 1000 CMT multilevel wells have been installed in North America and Europe to depths up to 260 feet (79 m) below ground surface. These wells have been installed in boreholes created in unconsolidated sediments and bedrock using a wide range of drilling equipment, including sonic, air rotary, diamond-bit coring, hollow-stem auger, and direct push. This paper presents a discussion of three field trials of the system, demonstrating its versatility and illustrating the type of depth-discrete data that can be collected with the system. 相似文献
9.
Summary In sand-filled river channels in arid parts of South West Africa it is of importance to find methods of locating the rock surface under the sand, for purposes of water supply. This paper describes preliminary investigations in three such river beds, to test the applicability to this problem of the seismic refraction method, using the hammer-electronic seismic instrument previously developed by one of the writers for shallow refraction work. Both the method in general, and the instrument in particular, proved satisfactory. Examples are given of travel-time diagrams, interpretation is discussed, and channel profiles deduced from the work are shown. Depths ranged from a few feet to a few tens of feet. At two of the three sites, variations in velocity in the sand made standard calculations of dip and depth from two-way shooting inapplicable. In such situations depth could still be estimated reasonably reliably near the origin of the traverse. There was evidence of a superficial layer in which the velocity was less than that of sound in air. 相似文献
10.
Vratislav Blecha Tomáš Fischer Petr Tábořík Jan Vilhem Radek Klanica Jan Valenta Petra Štěpančíková 《Studia Geophysica et Geodaetica》2018,62(4):660-680
The western part of the Bohemian Massif hosts an intersection of two regional fault zones, the SW-NE trending Oh?e/Eger Graben and the NNW-SSE trending Mariánské Lázně Fault, which has been reactivated several times in the geological history and controlled the formation of the Tertiary Cheb Basin. The broader area of the Cheb Basin is also related to permanent seismic activity of ML 3+ earthquake swarms. The Eastern Marginal Fault of the Cheb Basin (northern segment of the Mariánské Lázně Fault) separates the basin sediments and underlying granites in the SW from the Kru?né Hory/Erzgebirge Mts. crystalline unit in the NE. We describe a detailed geophysical survey targeted to locating the Eastern Marginal Fault and determining its geometry in the depth. The survey was conducted at the Kopanina site near the Nový Kostel focal zone, which shows the strongest seismic activity of the whole Western Bohemia earthquake swarm region. Complex geophysical survey included gravimetry, electrical resistivity tomography, audiomagnetotellurics and seismic refraction. We found that the rocks within the Eastern Marginal Fault show low resistivity, low seismic velocity and density, which indicates their deep fracturing, weathering and higher water content. The dip of the fault in shallow depths is about 60° towards SW. At greater depths, the slope turns to subvertical with dip angle of about 80°. Results of geoelectrical methods show blocky fabric of the Cheb Basin and deep weathering of the granite bedrock, which is consistent with geologic models based on borehole surveys. 相似文献
11.
结合汶川地震断裂带动态监测,利用快速响应探测系统,开展了断层带浅部结构人工地震探测.针对地震断裂带动态监测条件下的复杂波场和低信噪比的情况,在f-k波场分离的基础上,分别利用了折射波共中心点成像、面波速度反演、反射波叠加成像方法,进行了浅层断层和构造成像处理,并对处理结果进行了综合解释,给出了断裂带浅部断层分布和速度特征.为汶川地震龙门山断裂带东北端动态监测提供了基础结构信息,所发展的断裂带快速响应探测技术对于地震应急动态监测具有重要意义. 相似文献
12.
Shawn G. Benner David W. Blowes Carol J. Ptacek 《Ground Water Monitoring & Remediation》1997,17(4):99-107
The generation and release of acidic drainage containing high concentrations of dissolved metals from decommissioned mine wastes is an environmental problem of international scale. A potential solution to many acid drainage problems is the installation of permeable reactive walls into aquifers affected by drainage water derived from mine waste materials. A permeable reactive wall installed into an aquifer impacted by low-quality mine drainage waters was installed in August 1995 at the Nickel Rim mine site near Sudbury, Ontario. The reactive mixture, containing organic matter, was designed to promote bacterially mediated sulfate reduction and subsequent metal sulfide precipitation. The reactive wall is installed to an average depth of 12 feet (3.6 m) and is 49 feet (15 m) long perpendicular to ground water flow. The wall thickness (flow path length) is 13 feet (4 m). Initial results, collected nine months after installation, indicate that sulfate reduction and metal sulfide precipitation is occurring. Comparing water entering the wall to treated water exiting the wall, sulfate concentrations decrease from 2400 to 4600 mg/L to 200 to 3600 mg/L; Fe concentrations decrease from 250 to 1300 mg/L to 1.0 to 40 mg/L; pH increases from 5.8 to 7.0; and alkalinity (as CaCO3 ) increases from 0 to 50 mg/L to 600 to 2000 mg/L. The reactive wall has effectively removed the capacity of the ground water to generate acidity on discharge to the surface. Calculations based on comparison to previously run laboratory column experiments indicate that the reactive wall has potential to remain effective for at least 15 years. 相似文献
13.
The screened auger is a laser-slotted, hollow-stem auger through which a representative sample of ground water is pumped from an aquifer and tested for water-quality parameters by appropriate field-screening methods. Screened auger sampling can be applied to ground water quality remedial investigations, providing:(1) a mechanism for determining a monitoring well's optimal screen placement in a contaminant plume; and (2) data to define the three-dimensional configuration of the contaminant plume.
Screened auger sampling has provided an efficient method for investigating hexavalent chromium and volatile organic compound contamination in two sandy aquifers in Cadillac, Michigan. The aquifers approach 200 feet in thickness and more than 1 square mile in area. A series of screened auger borings and monitoring wells was installed, and ground water was collected at 10-foot intervals as the boreholes were advanced to define the horizontal and vertical distribution of the contaminant plumes. The ability of the screened auger to obtain representative ground water samples was supported by the statistical comparison of field screening results and subsequent laboratory analysis of ground water from installed monitoring wells. 相似文献
Screened auger sampling has provided an efficient method for investigating hexavalent chromium and volatile organic compound contamination in two sandy aquifers in Cadillac, Michigan. The aquifers approach 200 feet in thickness and more than 1 square mile in area. A series of screened auger borings and monitoring wells was installed, and ground water was collected at 10-foot intervals as the boreholes were advanced to define the horizontal and vertical distribution of the contaminant plumes. The ability of the screened auger to obtain representative ground water samples was supported by the statistical comparison of field screening results and subsequent laboratory analysis of ground water from installed monitoring wells. 相似文献
14.
All public agencies involved in ground water monitoring and protection face the requirement of obtaining well drilling services consistent with their needs. Most will rely on contracted drilling services, but a limited number of agencies having responsibilities for long-term aquifer monitoring and the promulgation of monitoring standards may find that implementing an in-house well drilling program is an effective approach to achieving their ground water protection goals.
Suffolk County, located on Long Island, New York, has been operating a well drilling program for 10 years, with three levels of drilling capability to meet the requirements of characterizing and monitoring an unconsolidated regional aquifer system. The program's cost and labor requirements are substantial, but this approach has provided uniformly high-quality data and the hands-on experience needed to test drilling innovations and produce monitoring regulations that are effective and feasible. If soundly organized and run, an agency-directed drilling operation will be readily adaptable to changing needs and priorities. In Suffolk County, this has included emergency response and fuel-spill monitoring. A successful program must also include a demonstrated geologic identification and well logging capability, close laboratory support, and an experienced hydrogeological or ground water engineering staff.
This approach may be suitable for other regional agencies based on their ground water conditions and water-supply protection needs. 相似文献
Suffolk County, located on Long Island, New York, has been operating a well drilling program for 10 years, with three levels of drilling capability to meet the requirements of characterizing and monitoring an unconsolidated regional aquifer system. The program's cost and labor requirements are substantial, but this approach has provided uniformly high-quality data and the hands-on experience needed to test drilling innovations and produce monitoring regulations that are effective and feasible. If soundly organized and run, an agency-directed drilling operation will be readily adaptable to changing needs and priorities. In Suffolk County, this has included emergency response and fuel-spill monitoring. A successful program must also include a demonstrated geologic identification and well logging capability, close laboratory support, and an experienced hydrogeological or ground water engineering staff.
This approach may be suitable for other regional agencies based on their ground water conditions and water-supply protection needs. 相似文献
15.
The frequency characteristics of near-surface sediments obtained from small scale S-wave refraction measurements conducted at two sites in the Garf Hussein area, contiguous to the High Dam Lake, South of Aswan, have shown drastic changes in the frequency-selective amplification of horizontal ground motion within a relatively short surface distance. This effect is attributed mainly to such factors as the variation in layer thickness and the presence or absence of soft alluvial deposits.These results indicate that movements initiated deep in the earth's crust may not be faithfully reflected on the ground surface. As geodetic work principally involves monitoring relative horizontal and vertical displacements on the earth's surface with time, geodesists are advised to take the spectral response of the ground into consideration. 相似文献
16.
Hydrogeologic and ground water quality data obtained from a gas-driven multilevel sampler system and a polyvinyl chloride (PVC) monitoring well nest with the same aquifer communication intervals are compared. All monitoring points are in close proximity to each other. The study was conducted at an eight-acre uncontrolled hazardous waste site. The site is located in an alluvial valley composed of approximately 40 feet of alluvium overlying shale bedrock. The ground water at the site is contaminated with various organic constituents. A ground water monitoring network consisting of 26 conventional monitoring wells, nine observation well points, and six multilevel gas-driven samplers was established to characterize the hydrogeologic regime and define the vertical and horizontal extent of contamination in the vicinity of the abandoned chemical plant. As part of this study, a multilevel monitoring system was installed adjacent to a well nest. The communication zones of the multilevel samplers were placed at the same elevation as the sand packs of the well nest. The multilevel sampler system and well nest are located in a contaminated area directly downgradient of the site. A comparison of the vertical head distribution and ground water quality was performed between the well nest and the multilevel sampling system. The gas-driven multilevel sampling system consists of three gas-driven samplers that monitor separate intervals in the unconsolidated materials. The well nest, composed of two PVC monitoring wells in separate boreholes, has the same communication interval as the other two gas-driven samplers. Hydraulic head information for each multilevel sampler was obtained using capillary tubing. This was compared with heads obtained from the well nest utilizing an electric water level indicator. Chemical analyses from the PVC and multilevel sampler wells were performed and compared with one another. The analyses included organic acids, base neutrals, pesticides, PCBs, metals, volatile organics, TOX, TOC, CN, pH and specific conductance. 相似文献
17.
在城市活断层勘探中,对于面波干扰大、地震反射波法难以开展工作的区域,可尝试利用地震折射波法进行探测,并对折射波法探测的原始记录采用时间项、差异时距曲线和有限差分成像等方法进行综合计算、分析,以探索折射波法在城市活断层勘探中的应用成效。文中针对郑州市须水断层西段浅层地震折射波法勘探记录,利用时间项、差异时距曲线和有限差分成像等计算方法,获取剖面速度结构与界面构造;综合震相特征、计算结果等资料确定主要地层的界面深度和构造特征,3种方法都取得了相近的结论。后又通过在测线上4个钻孔资料的验证,认为3种方法的计算结果与钻孔资料相吻合,说明折射波法勘探在城市活断层探测中的应用是可行的 相似文献
18.
随着非常规气藏的开采开发,微地震监测成为压裂效果评估的关键技术.四川盆地非常规油气藏开采开发处于早期,井网密度极低导致在压裂井附近难以找到匹配深井作为观测井,而地面、浅井等替代观测方式面临无法有效探测微地震信号的风险.微地震事件能量弱和辐射的方向性使得观测方位预判及有效监测距离的评估成为微地震监测成败的关键因素.本文提出一种基于压裂微地震能量辐射模式和地层传播特征的相对震级计算技术,模拟微地震事件能量辐射模式及在地层传播过程中的动力学特征,达到评估微地震相对震级与检波器方位、地层传播距离的非线性关系的目的.通过理论分析和实际微地震监测资料验证,该方法能有效地解决微地震监测最佳观测方位的优选和有效传播距离的评估问题. 相似文献
19.
The present study investigates the possible hydrologic effects of the proposed lignite open‐cast mining in Drama lignite field (north Greece). Recent years have seen a rapid increase in surface mining. This activity has generated a growing concern for the potential environmental impacts associated with large scale surface mining. In order to achieve a safe mine operation and allow extraction of lignite to considerable depths, extensive dewatering by pumping will be necessary, while at the same time it is desirable to avoid presence of overpumping conditions in the broader area. Based on stratigrafic, hydrologic and hydrogeologic data, a three‐dimensional finite difference model was developed in order to simulate the dewatering process of the western part of the lignite open‐cast mine in Drama and to predict both spatially and temporally the decline of ground water level down to the lignite surface. The dewatering of the part of the aquifer which underlies the mine area will influence the hydrological conditions of the broader region. The most important anticipated effects will be the abandonment of shallow wells as well as the decrease of ground water pumping rates of deep wells. Aquifer discharge towards the ditches of the study area will cease and there will be an inversion of ground water flow from the ditches towards the underlying aquifer. Dewatering activities will probably result in minor subsidence of the nearby peat deposits of Drama Philippi marshes. Moreover, sand pumping as well as the presence of gasses is likely to cause local subsidence phenomena, mainly in the pit slopes. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
20.
Site effects in Mexico City: Constraints from surface wave inversion of shallow refraction data 总被引：1，自引：0，他引：1
J. Ramos-Martínez F.J. Chávez-García E. Romero-Jiménez J.L. Rodríguez-Zúñiga J.M. Gómez-González 《Journal of Applied Geophysics》1997,36(4):157-165
In order to understand and simulate site effects on strong ground motion records of recent earthquakes in Mexico City, it is fundamental to determine the in situ elastic and anelastic properties of the shallow stratigraphy of the basin. The main properties of interest are the shear wave velocities and Q-quality factors and their correlation with similar parameters in zones of the city. Despite population density and paved surfaces, it is feasible to gather shallow refraction data to obtain laterally homogeneous subsoil structures at some locations. We focused our analysis in the Texcoco Lake region of the northeastern Mexico City basin. This area consists of unconsolidated clay sediments, similar to those of the lake bed zone in Mexico City, where ground motion amplification and long duration disturbances are commonly observed. We recorded Rayleigh and Love waves using explosive and sledgehammer sources and 4.5 Hz vertical and horizontal geophones, respectively. Additionally, for the explosive source, we recorded three-component seismograms using 1 Hz seismometers. We obtained phase velocity dispersion curves from ray parameter-frequency domain analyses and inverted them for vertical distribution of S wave velocity. The initial model was obtained from a standard first-break refraction analysis. We also obtained an estimation of the QS shear wave quality factor for the uppermost stratigraphy. Results compare well with tilt and cone penetrometer resistance measurements at the same test site, emphasizing the importance of these studies for engineering purposes. 相似文献