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Wayne W. Lapham

Publications and source records attributed to Wayne W. Lapham.

14 recordsLinked to original sources
USGS2007

Application of electromagnetic logging to contamination investigations in glacial sand-and-gravel aquifers

Electromagnetic (EM) logging provides an efficient method for high‐resolution, vertical delineation of electrically conductive contamination in glacial sand‐and‐gravel aquifers. LM. gamma, and lithologic logs and specific conductance data from sand‐and‐gravel aquifers at five sites in the northeastern United States were analyzed to define the relation of KM conductivity to aquifer lithology and water quality. Municipal waste disposal, septic waste discharge, or highway deicing salt application at these sites has caused contaminant plumes in which the dissolved solids concentration and specific conductance of ground water exceed background levels by as much as 10 to 20 limes. The major hydrogeologic factors that affected KM log response at the five sites were the dissolved solids concentration of the ground water and the silt and clay content in the aquifer. KM conductivity of sand and gravel with uncontaminated water ranged from less than 5 to about 10 millisiemens per meter (mS/m); that of silt and clay zones ranged from about 15 to 45 mS/m: and that of the more highly contaminated zones in sand and gravel ranged from about 10 to more than 80 mS/m. Specific conductance of water samples from screened intervals in sand and gravel at selected monitoring well installations was significantly correlated with KM conductivity. CM logging can be used in glacial sand‐and‐gravel aquifer investigations to (1) determine optimum depths for the placement of monitoring well screens: (2) provide a nearly continuous vertical profile of specific conductance to complement depth‐specific water quality samples; and (3) identify temporal changes in water quality through sequential logging. Detailed lithologic or gamma logs, preferably both, need to be collected along with the F.M logs to define zones in which elevated EM conductivity is caused by the presence of sill and clay beds rather than contamination.

Connecticut, Massachusetts, New York, Vermont↗
USGS2006

Volatile organic compounds in the nation's ground water and drinking-water supply wells

This national assessment of 55 volatile organic compounds (VOCs) in ground water gives emphasis to the occurrence of VOCs in aquifers that are used as an important supply of drinking water. In contrast to the monitoring of VOC contamination of ground water at point-source release sites, such as landfills and leaking underground storage tanks (LUSTs), our investigations of aquifers are designed as large-scale resource assessments that provide a general characterization of water-quality conditions. Nearly all of the aquifers included in this assessment have been identified as regionally extensive aquifers or aquifer systems. The assessment of ground water (Chapter 3) included analyses of about 3,500 water samples collected during 1985-2001 from various types of wells, representing almost 100 different aquifer studies. This is the first national assessment of the occurrence of a large number of VOCs with different uses, and the assessment addresses key questions about VOCs in aquifers. The assessment also provides a foundation for subsequent decadal assessments of the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program to ascertain long-term trends of VOC occurrence in these aquifers.

Circular↗
USGS2006

The occurrence of volatile organic compounds in aquifers of the United States

The U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program recently completed a national assessment of volatile organic compounds (VOCs) in ground water (Zogorski and others, 2006). As part of this assessment, samples of ambient ground water collected from 3,498 wells during 1985-2002 were selected for characterizing the occurrence of 55 VOCs in 98 aquifer studies. The 55 VOCs were assigned to the following groups on the basis of their primary usage (or origin): (1) fumigants, (2) gasoline hydrocarbons, (3) gasoline oxygenates, (4) organic synthesis compounds, (5) refrigerants, (6) solvents, and (7) trihalo-methanes (chlorination by-products). The samples were collected throughout the conterminous United States as well as Alaska and Hawaii. The sampled wells had a variety of uses including domestic supply (61 percent), public supply (15 percent), monitoring (10 percent), other (13 percent), and unknown (1 percent). NAWQA aquifer studies are large-scale resource assessments of ground water that provide a general characterization of water-quality conditions in locally and regionally important aquifers or portions thereof. In general, the aquifers (or portions thereof) selected for study were some of the most intensively used aquifers for drinking water in greaterHawaiiOahuAlaskathe Nation. The 98 aquifer studies collectively provide an important national perspective on the current (1985-2002) extent of VOC contamination and regional patterns of VOC occurrence in ground water. More information about this national assessment of VOCs is available at a supporting Web site (http://water.usgs.gov/nawqa/vocs/national_assessment).

Scientific Investigations Map↗
USGS2002

Occurrence and status of volatile organic compounds in ground water from rural, untreated, self-supplied domestic wells in the United States, 1986-99

Samples of untreated ground water from 1,926 rural, self-supplied domestic wells were analyzed for volatile organic compounds (VOCs) during 1986-99. This information was used to characterize the occurrence and status of VOCs in domestic well water. The samples were either collected as part of the U.S. Geological Survey?s National Water-Quality Assessment (NAWQA) Program occurrence-assessment studies or were compiled by NAWQA from existing ambient ground-water or source-water-quality monitoring programs conducted by local, State, and other Federal agencies. Water samples were collected at the wellhead prior to treatment or storage. In most samples, 55 target VOCs were analyzed, and occurrence and status information generally was computed at an assessment level of 0.2 mg/L (microgram per liter). At least one VOC was detected in 12 percent of samples (232 samples) at an assessment level of 0.2 mg/L. This detection frequency is relatively low compared to the 26 percent detection frequency of at least one VOC in public sup-ply wells sampled by NAWQA, and the difference may be due, in part, to the higher pumping rates, pumping stress factors, and larger contributing areas of public supply wells. Samples with detections of at least one VOC were collected from wells located in 31 of 39 States. Solvents were the most frequently detected VOC group with detections in 4.6 percent of samples (89 samples) at an assessment level of 0.2 mg/L. The geographic distribution of detections of some VOC groups, such as fumigants and oxygenates, relates to the use pattern of com-pounds in that group. With the exception of com-pounds used in organic synthesis, detection frequencies of VOCs by group are proportional to the average half-life of compounds in the group. When the organic synthesis group is excluded from the analysis, a good correlation exists between the detection frequency of VOCs by group and average half-life of compounds in the group. Individually, VOCs were not commonly detected at an assessment level of 0.2 mg/L, with the seven most frequently detected VOCs found in only 1 to 5 percent of samples. Mixtures (two or more compounds) were a common mode of occurrence for VOCs when no assessment level was applied, and mixtures occurred in one-half of all samples that contained at least one VOC. Only 1.4 percent of samples (27 samples) had one or more VOC concentrations that exceeded a federally established drinking-water standard or health criterion. Only 0.1 percent of samples (2 samples) had one or more VOC concentrations that exceeded a taste/odor threshold. Potential point sources of VOCs near domestic wells are numerous. Leaks from under-ground storage tanks and aboveground storage tanks that hold gasoline, diesel fuel, or heating oil have the potential to be major point sources of contaminants to domestic wells. Shock chlorination may be a source of trichloromethane and other trihalomethanes in some domestic wells. Septic systems are believed to be an important source of contaminants to domestic wells, but extensive research on this subject does not exist. VOCs frequently are ingredients in household products such as cleansers and insecticides, and some VOCs have been found in septic systems.

Water-Resources Investigations Report↗
USGS1995

Ground-Water Data-Collection Protocols and Procedures for the National Water-Quality Assessment Program: Selection, Installation, and Documentation of Wells, and Collection of Related Data

Protocols for well installation and documentation are included in a 1989 report written for the National Water-Quality Assessment (NAWQA) Pilot Program of the U.S. Geological Survey (USGS). These protocols were reviewed and revised to address the needs of the full-scale implementation of the NAWQA Program that began in 1991. This report, which is a collaborative effort between the National Water-Quality Assessment Program and the Office of Water Quality, is the result of that review and revision. This report describes protocols and recommended procedures for the collection of data from wells for the NAWQA Program. Protocols and procedures discussed are well selection, installation of monitoring wells, documentation, and the collection of water level and additional hydrogeologic and geologic data.

Open-File Report↗
USGS1995

Ground-Water Data-Collection Protocols and Procedures for the National Water-Quality Assessment Program: Collection and Documentation of Water-Quality Samples and Related Data

Protocols for ground-water sampling are described in a report written in 1989 as part of the pilot program for the National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey (USGS). These protocols have been reviewed and revised to address the needs of the full-scale implementation of the NAWQA Program that began in 1991. This report, which is a collaborative effort between the NAWQA Program and the USGS Office of Water Quality, is the result of that review and revision. This report describes protocols and recommended procedures for the collection of water-quality samples and related data from wells for the NAWQA Program. Protocols and recommended procedures discussed include (1) equipment setup and other preparations for data collection; (2) well purging and field measurements; (3) collecting and processing ground-water-quality samples; (4) equipment decontamination; (5) quality-control sampling; and (6) sample handling and shipping.

Open-File Report↗
USGS1992

Geohydrology and simulated ground-water flow, Plymouth-Carver aquifer, southeastern Massachusetts

The Plymouth-Carver aquifer underlies an area of 140 square miles and is the second largest aquifer in areal extent in Massachusetts. It is composed primarily of saturated glacial sand and gravel. The water-table and bedrock surface were mapped and used to determine saturated thickness of the aquifer, which ranged from less than 20 feet to greater than 200 feet. Ground water is present mainly under unconfined conditions, except in a few local areas such as beneath Plymouth Harbor. Recharge to the aquifer is derived almost entirely from precipitation and averages about 1.15 million gallons per day per square mile. Water discharges from the aquifer by pumping, evapotranspiration, direct evaporation from the water table, and seepage to streams, ponds, wetlands, bogs, and the ocean. In 1985, water use was about 59.6 million gallons per day, of which 82 percent was used for cranberry production. The Plymouth-Carver aquifer was simulated by a three-dimensional, finite difference ground-water-flow model. Most model boundaries represent the natural hydrologic boundaries of the aquifer. The model simulates aquifer recharge, withdrawals by pumped wells, leakage through streambeds, and discharge to the ocean. The model was calibrated for steady-state and transient conditions. Model results were compared with measured values of hydraulic head and ground-water discharge. Results of simulations indicate that the modeled ground-water system closely simulates actual aquifer conditions. Four hypothetical ground-water development alternatives were simulated to demonstrate the use of the model and to examine the effects on the ground-water system. Simulation of a 2-year period of no recharge and average pumping rates that occurred from 1980-85 resulted in water-level declines exceeding 5 feet throughout most of the aquifer and a decrease of 54 percent in average ground-water discharge to streams. In a second simulation, four wells in the northern part of the area were pumped at 10.4 million gallons per day in excess of rates simulated in the steady-state model for the four wells. This resulted in water-level declines of 2 feet or more in an area of 25 square miles and a decline in average ground-water discharge to streams of 6 percent. When this pumpage was simulated as recharge to the aquifer, water levels beneath the recharge area rose more than 40 feet, and ground-water discharge remained equal to average discharge in the calibrated steady-state model. In a third simulation, all 21 existing production wells were pumped at nearly the design capacity of 17.8 million gallons per day; this pumping rate produced water-level declines of less than 2 feet throughout most of the aquifer. When simulated pumpage was increased to 32.8 million gallons per day from existing wells and from 15 additional wells, the area where water-level declines exceeded 2 feet significantly increased. In another set of simulations, a well field close to a stream was pumped at rates of 2, 4, and 6 million gallons per day. At a pumping rate of 6 million gallons per day, ground-water discharge to the stream decreased 34 percent during periods of normal precipitation and 56 percent during drought conditions.

Massachusetts↗
USGS1989

Yield and quality of ground water from stratified-drift aquifers, Taunton River basin, Massachusetts : executive summary

Water shortages are a chronic problem in parts of the Taunton River basin and are caused by a combination of factors. Water use in this part of the Boston metropolitan area is likely to increase during the next decade. The Massachusetts Division of Water Resources projects that about 50% of the cities and towns within and on the perimeter of the basin may have water supply deficits by 1990 if water management projects are not pursued throughout the 1980s. Estimates of the long-term yield of the 26 regional aquifers indicate that the yields of the two most productive aquifers equal or exceed 11.9 and 11.3 cu ft/sec, 90% of the time, respectively, if minimum stream discharge is maintained at 99.5% flow duration. Eighteen of the 26 aquifers were pumped for public water supply during 1983. Further analysis of the yield characteristics of these 18 aquifers indicates that the 1983 pumping rate of each of these 18 aquifers can be sustained at least 70% of the time. Selected physical properties and concentrations of major chemical constituents in groundwater from the stratified-drift aquifers at 80 sampling sites were used to characterize general water quality in aquifers throughout the basin. The pH of the groundwater ranged from 5.4 to 7.0. Natural elevated concentrations of Fe and Mn in water in the stratified-drift aquifers are present locally in the basin. Natural concentrations of these two metals commonly exceed the limits of 0.3 mg/L for Fe and 0.05 mg/L for Mn recommended for drinking water. Fifty-one analyses of selected trace metals in groundwater samples from stratified-drift aquifers throughout the basin were used to characterize trace metal concentrations in the groundwater. Of the 10 constituents sampled that have US EPA limits recommended for drinking water, only the Pb concentration in water at one site (60 micrograms/L) exceeded the recommended limit of 50 micrograms/L. Analyses of selected organic compounds in water in the stratified-drift aquifers at 74 locations revealed that 13 of the sample contained one or more of the following compounds: chloroform; carbon tetrachloride; dichloroethane; dichloroethylene; tetrachloroethylene; and, toluene. (Lantz-PTT)

Water-Resources Investigations Report↗
USGS1989

Use of temperature profiles beneath streams to determine rates of vertical ground-water flow and vertical hydraulic conductivity

The use of temperature profiles beneath streams to determine rates of vertical ground-water flow and effective vertical hydraulic conductivity of sediments was evaluated at three field sites by use of a model that numerically solves the partial differential equation governing simultaneous vertical flow of fluid and heat in the Earth. The field sites are located in Hardwick and New Braintree, Mass., and in Dover, N.J. In New England, stream temperature varies from about 0 to 25 ?C (degrees Celsius) during the year. This stream-temperature fluctuation causes ground-water temperatures beneath streams to fluctuate by more than 0.1 ?C during a year to a depth of about 35 ft (feet) in fine-grained sediments and to a depth of about 50 ft in coarse-grained sediments, if ground-water velocity is 0 ft/d (foot per day). Upward flow decreases the depth affected by stream-temperature fluctuation, and downward flow increases the depth. At the site in Hardwick, Mass., ground-water flow was upward at a rate of less than 0.01 ft/d. The maximum effective vertical hydraulic conductivity of the sediments underlying this site is 0.1 ft/d. Ground-water velocities determined at three locations at the site in New Braintree, Mass., where ground water discharges naturally from the underlying aquifer to the Ware River, ranged from 0.10 to 0.20 ft/d upward. The effective vertical hydraulic conductivity of the sediments underlying this site ranged from 2.4 to 17.1 ft/d. Ground-water velocities determined at three locations at the Dover, N.J., site, where infiltration from the Rockaway River into the underlying sediments occurs because of pumping, were 1.5 ft/d downward. The effective vertical hydraulic conductivity of the sediments underlying this site ranged from 2.2 to 2.5 ft/d. Independent estimates of velocity at two of the three sites are in general agreement with the velocities determined using temperature profiles. The estimates of velocities and conductivities derived from the temperature measurements generally fall within the ranges of expected rates of flow in, and conductivities of, the sediments encountered at the test sites. Application of the method at the three test sites demonstrates the feasibility of using the method to determine the rate of ground-water flow between a stream and underlying sediments and the effective vertical hydraulic conductivity of the sediments.

Water Supply Paper↗
USGS1988

Yield and quality of ground water from stratified-drift aquifers, Taunton River basin, Massachusetts

Glacial stratified-drift deposits composed primarily of sand and gravel form the major aquifers in the Taunton River basin. In the northern half of the basin, the aquifers are long, narrow, and thin, and saturated thicknesses range from about 20 feet to slightly more than 100 feet. Aquifer widths range from about 0.1 mile to 1.5 miles, and lengths range from about 1 mile to 5 miles. Aquifer yield from storage, representative of short-term yield during severe drought conditions, were estimated for 26 selected aquifers in the basin. For a 30-day pumping period, 14 aquifers have yields less than 5 ft 3 /s (cubic feet per second), 7 have yields of from 5 to 10 ft 3 /s; and 5 have yields of from 10 to 15 ft 3 /s. Aquifer yields under normal climatic conditions were estimated for the 26 aquifers by considering the cumulative yield from intercepted ground-water discharge, induced infiltration, and storage. These yield estimates are related to the estimated duration of flow of the stream that drains the aquifer. The two highest aquifer yields equal or exceed 11.9 and 11.3 ft 3 /s 90 percent of the time, respectively, if minimum stream discharge is maintained at 99.5 percent flow duration. Water for public supply was pumped in 18 of the 26 aquifers during 1983, and all the developed aquifers were pumped at a rate either equal to or greater than 70 percent of the estimated rate of aquifer yield determined in this study. The pH of the ground water ranges from 5.4 to 7.0, which categorizes the water as mildly corrosive. Hardness of the ground water ranges from 9 to 112 mg/L (milligrams per liter). No concentrations of sulfate or chloride exceeded EPA recommended limits for drinking water. However, concentrations of sodium exceeded the Massachusetts recommended limit for drinking water for those individuals on a sodium-restricted diet of 20 mg/L in 19 of the samples. Natural concentrations of iron and manganese commonly exceed the limits of 0.3 mg/L and 0.05 mg/L recommended for drinking water. Of 51 analyses for trace metals, including arsenic, barium, cadmium, chromium, copper, cyanide, lead, mercury, selenium, silver, zinc, and nickel, only lead, with a concentration of 60 ug/L (micrograms per liter) exceeded the recommended limit of 50 ug/L at one site. In 13 of 74 analyses for selected organic compounds, one or more of the following compounds were detected: Chloroform; carbon tetrachloride; 1,1 dichloroethane; 1,2 transdichloroethylene; tetrachloroethylene; toluene; 1,1,1 trichloroethane; and trichloroethylene. The U.S. Environmental Protection Agency has set Maximum Contaminant Levels (MCLs) for three of these compounds. These three compounds and their MCLs are: Trichloroethylene, 5 ug/L; carbon tetrachloride, 5 ug/L; and 1,1,1-trichloroethane, 200 ug/L. Trichloroethylene was detected in five samples. The concentration of trichloroethylene in one of these five samples exceeded the limit of 5 ug/L. A concentration of carbon tetrachloride of 0.8 ug/L was detected in one sample, which is below the limit of 5 ug/L. Concentrations of 1,1,1 trichloroethane were detected in ten samples, but none exceeded the limit for that compound.

Massachusetts↗
USGS1982

Ground-water resources of the White River basin, Delaware County, Indiana

The ground-water resources of the White River basin in and near Delaware County, Indiana, were investigated by mapping the aquifers, calculating their hydraulic properties, determining the distribution of potentiometric head, and determining some of the components of the ground-water budget from data collect ed in the field. This information was used to construct and calibrate a seven- layer, digital ground-water-flow model. The model, constructed and calibrated to water-level and seepage data collected during the study, simulates conditions for the autumn of 1977. The model was used to assess ground-water potential in terms of yield, drawdown, and streamflow depletion. Drift covers nearly the entire area and generally ranges in thickness from 0 to 500 feet. Beneath the drift lie Silurian and Ordovician limestone, dolomite, and shale. A bedrock valley trends east-west through the center of the area. Bedrock surface relief is about 400 feet. Six confined sand and gravel aquifers interbedded in the drift, a bedrock aquifer, and an unconfined outwash aquifer are the three major aquifer systems. The nearly horizontal, areally discontinuous, confined sand and gravel aquifers generally range in thickness from 5 to 40 feet and have an average hydraulic conductivity estimated to be 433 feet per day. The bedrock aquifer underlying all of Delaware County has a permeable thickness estimated to be 150 feet and an average transmissivity of 1,000 square feet per day. Observation-well records indicate that water-level fluctuation is seasonal and has no long-term trends. Municipal and industrial ground-water pumpage for 1976 was 3.1 million gallons per day (4.8 cubic feet per second). On October 29, 1977, when the flow duration in the White River at Muncie was 80 percent, ground-water seepage to streams was 81 cubic feet per second. The water budget simulated in the model indicated that the rate of inflow to the ground-water system in the modeled area is 102 cubic feet per second: 80 percent from effective areal recharge of precipitation and 20 percent from ground-water flow across the area boundaries. Two percent of the ground-water discharge is pump-age, 66 percent is seepage to streams, and the remaining 32 percent is flow across the area boundaries. Simulations of seven pumping plans provide a general assessment of the water-yielding potential of the three major aquifer systems. Model results indicate that as much as 3 million gallons per day can be developed from well fields where the average drawdown is 20 feet. Model simulations also indicate that 7 million gallons per day is available from a potential well field around Muncie.

Indiana↗
USGS1981

Ground-water resources of the White River basin, Madison County, Indiana

The ground-water resources of the White River basin in and near Madison County, Indiana, were investigated by mapping the aquifers, estimating their hydraulic properties, determining the distribution of potentiometric head in the aquifers, and estimating some of the components of the ground-water budget from data collected in the field. This information was used to con struct and calibrate a five-layer, digital ground-water flow model. The mod el, constructed and calibrated to ground-water-level and seepage data col lected during the study, simulates conditions for the autumn of 1976. The model was used to provide estimates of ground-water potential in terms of yield, drawdown, and depletion in streamflow. Glacial drift covers nearly the entire study area and ranges in thickness from 0 to approximately 300 feet. Beneath the drift lie Ordovician to Devonian limestone, dolomite, and shale. A bedrock valley trends west-northwest through the center of the study area. Relief of the bedrock surface is approximately 325 feet. Four confined sand and gravel aquifers interbedded in the glacial drift, a bedrock aquifer, and an unconfined outwash aquifer are the three most important aquifer systems in the study area. The nearly horizontal, areally discontinuous, confined sand and gravel aquifers have an average thickness of about 15 feet and an average hydraulic conductivity estimated to be 433 feet per day. The bedrock aquifer underlying the entire study area has a thick-ness estimated to be 150 feet and an average transmissivity estimated in previous studies in the basin to be 1,340 square feet per day. The unconfined outwash aquifer, although thin and narrow, is an important aquifer because of its proximity to sources of induced recharge. Water-level fluctuations in observation wells in the basin indicate that the ground-water system is in dynamic equilibrium. Ground-water seepage to streams at 90-percent flow duration on October 1, 1976, was estimated to be between 15.9 and 74.4 cubic feet per second. Ground-water pumpage for 1976 was estimated to be 19.7 million gallons per day (30.5 cubic feet per second). The water budget, as simulated in the model, indicates that the rate of inflow to the ground-water system in the modeled area is 92.4 cubic feet per second. Of this, 78 percent is from effective areal recharge of precipitation, and 22 percent is from ground-water flow across the boundaries into the study area. Thirty-three percent of the ground-water outflow is pumpage, 59 percent is seepage to streams, and the remaining 8 percent is ground-water flow across the boundaries out of the study area. Model simulations of eight pumping plans provide a general assessment of the water-yielding potential of the three major aquifer systems and indicate that as much as 2.5 million gallons per day can be obtained from well fields about half a square mile in area. Model results also indicate that, for as much as 2.5-million gallons per day pumping, flow in the large streams will not be significantly affected, whereas flow in the small streams may be significantly affected. In addition, simulations indicate that adding more wells to the well field northwest of Anderson, Ind., would probably be no more advantageous than increasing the pumpage in the existing wells. How-ever, well interference, well hydraulics, and pumping-level constraints were not considered in the investigation of alternative methods of expanding the well field. In developing the ground-water system in the area, use of many small, scattered well fields that produce less than about 3 million gallons per day may be more favorable hydrologically than a few, heavily pumped well fields.

Indiana↗
USGS1980

Reassessment of the effects of construction dewatering on ground-water levels in the Cowles Unit, Indiana Dunes National Lakeshore, Indiana : Supplement to Geological Survey Water Resources Investigations 78-138

A revised dewatering plan for the construction of a nuclear power plant at the Northern Indiana Public Service Company 's (NIPSCO) Bailly Generating Station and evidence that suggests that a change in the characteristics of the confining unit 2 in and near Cowles Bog National Landmark may exist have resulted in a reassessment of the effects of construction dewatering on ground-water levels in the Indiana Dunes National Lakeshore. Model results indicate that the revision in the dewatering plan produces water-level declines that do not differ significantly from those described previously. However, when the change in the confining unit beneath Cowles Bog is considered, simulations of the simultaneous decline of a seepage mound after sealing of the fly-ash-ponds and the second phase of construction dewatering indicate that the simulated water-level declines in the aquifer unit 1 at Cowles Bog may be below the water levels tolerated by the National Park Service after 18 months. The water levels may even decline below the tolerable levels in spite of NIPSCO 's proposed plan of artificially recharging the aquifer unit 1 near the excavation site at 400 gal/min. The magnitude of the simulated water-level declines in unit 1 within the Lakeshore, caused by pumping from the excavation, depends on the relation in time between the second phase of dewatering and the decline of the seepage mound after sealing of the fly-ash-ponds, but not on the duration of dewatering beyond 18 months. (USGS)

Indiana↗