Geology Reports⌕ Search

Geology topics

Janet Radway Stone

Publications and source records attributed to Janet Radway Stone.

28 records · Page 2Linked to original sources
USGS2000

Delineation and Analysis of Uncertainty of Contributing Areas to Wells at the Southbury Training School, Southbury, Connecticut

Contributing areas to public-supply wells at the Southbury Training School in Southbury, Connecticut, were mapped by simulating ground-water flow in stratified glacial deposits in the lower Transylvania Brook watershed. The simulation used nonlinear regression methods and informational statistics to estimate parameters of a ground-water flow model using drawdown data from an aquifer test. The goodness of fit of the model and the uncertainty associated with model predictions were statistically measured. A watershed-scale model, depicting large-scale ground-water flow in the Transylvania Brook watershed, was used to estimate the distribution of groundwater recharge. Estimates of recharge from 10 small basins in the watershed differed on the basis of the drainage characteristics of each basin. Small basins having well-defined stream channels contributed less ground-water recharge than basins having no defined channels because potential ground-water recharge was carried away in the stream channel. Estimates of ground-water recharge were used in an aquifer-scale parameter-estimation model. Seven variations of the ground-water-flow system were posed, each representing the ground-water-flow system in slightly different but realistic ways. The model that most closely reproduced measured hydraulic heads and flows with realistic parameter values was selected as the most representative of the ground-water-flow system and was used to delineate boundaries of the contributing areas. The model fit revealed no systematic model error, which indicates that the model is likely to represent the major characteristics of the actual system. Parameter values estimated during the simulation are as follows: horizontal hydraulic conductivity of coarse-grained deposits, 154 feet per day; vertical hydraulic conductivity of coarse-grained deposits, 0.83 feet per day; horizontal hydraulic conductivity of fine-grained deposits, 29 feet per day; specific yield, 0.007; specific storage, 1.6E-05. Average annual recharge was estimated using the watershed-scale model with no parameter estimation and was determined to be 24 inches per year in the valley areas and 9 inches per year in the upland areas. The parameter estimates produced in the model are similar to expected values, with two exceptions. The estimated specific yield of the stratified glacial deposits is lower than expected, which could be caused by the layered nature of the deposits. The recharge estimate produced by the model was also lower?about 32 percent of the average annual rate. This could be caused by the timing of the aquifer test with respect to the annual cycle of ground-water recharge, and by some of the expected recharge going to parts of the flow system that were not simulated. The data used in the calibration were collected during an aquifer test from October 30 to November 4, 1996. The model fit was very good, as indicated by the correlation coefficient (0.999) between the weighted simulated values and weighted observed values. The model also reproduced the general rise in ground-water levels caused by ground-water recharge and the cyclic fluctuations caused by pumping prior to the aquifer test. Contributing areas were delineated using a particle-tracking procedure. Hypothetical particles of water were introduced at each model cell in the top layer and were tracked to determine whether or not they reached the pumped well. A deterministic contributing area was calculated using the calibrated model, and a probabilistic contributing area was calculated using a Monte Carlo approach along with the calibrated model. The Monte Carlo simulation was done, using the parameter variance/covariance matrix generated by the regression model, to estimate probabilities associated with the contributing area to the wells. The probabilities arise from uncertainty in the estimated parameter values, which in turn arise from the adequacy of the data available to comprehensively describe the groundwater-flow sy

Water-Resources Investigations Report↗
USGS1999

Characteristics of fractures in crystalline bedrock determined by surface and borehole geophysical surveys, eastern surplus superfund site, Meddybemps, Maine

Surface and borehole geophysical methods were used to determine fracture orientation in crystalline bedrock at the Eastern Surplus Superfund Site in Meddybemps, Maine. Fracture-orientation information is needed to address concerns about the fate of contaminants in ground water at the site. Azimuthal square-array resistivity surveys were conducted at 3 locations at the site, borehole-acoustic televiewer and borehole-video logs were collected in 10 wells, and single-hole directional radar surveys were conducted in 9 wells. Borehole-video logs were used to supplement the results of other geophysical techniques and are not described in this report. Analysis of azimuthal square-array resistivity data indicated that high-angle fracturing generally strikes northeast-southwest at the three locations. Borehole-acoustic televiewer logs detected one prominent low-angle and two prominent high-angle fracture sets. The low-angle fractures strike generally north-northeast and dip about 20 degrees west-northwest. One high-angle fracture set strikes north-northeast and dips east-southeast; the other high-angle set strikes east-northeast and dips south-southeast. Single-hole directional radar surveys identified two prominent fracture sets: a low-angle set striking north-northeast, dipping west-northwest; and a high-angle fracture set striking north-northeast, dipping east-southeast. Two additional high-angle fracture sets are defined weakly, one striking east-west, dipping north; and a second striking east-west, dipping south. Integrated results from all of the geophysical surveys indicate the presence of three primary fracture sets. A low-angle set strikes north-northeast and dips west-northwest. Two high-angle sets strike north-northeast and east-northeast and dip east-southeast and south-southeast. Statistical correction of the fracture data for orientation bias indicates that high-angle fractures are more numerous than observed in the data but are still less numerous than the low-angle fractures. The orientation and distribution of water-yielding fractures sets were determined by correlating the fracture data from this study with previously collected borehole-flowmeter data. The water-yielding fractures are generally within the three prominent fracture sets observed for the total fracture population. The low-angle water-yielding fractures primarily strike north-northeast to west-northwest and dip west-northwest to south-southwest. Most of the high-angle water-yielding fractures strike either north-northeast or east-west and dip east-southeast or south. The spacing between water-yielding fractures varies but the probable average spacing is estimated to be 30 feet for low-angle fractures; 27 feet for the east-southeast dipping, high-angle fractures; and 43 feet for the south-southeast dipping, high-angle fractures. The median estimated apparent transmissivity of individual water-yielding fractures or fracture zones was 0.3 feet squared per day and ranged from 0.01 to 382 feet squared per day. Ninety-five percent of the water-yielding fractures or fracture zones had an estimated apparent transmissivity of 19.5 feet squared per day or less. The orientation, spacing, and hydraulic properties of water-yielding fractures identified during this study can be used to help estimate recharge, flow, and discharge of ground water contaminants. High-angle fractures provide vertical pathways for ground water to enter the bedrock, interconnections between low-angle fractures, and, subsequently, pathways for water flow within the bedrock along fracture planes. Low-angle fractures may allow horizontal ground-water flow in all directions. The orientation of fracturing and the hydraulic properties of each fracture set strongly affect changes in ground-water flow under stress (pumping) conditions.

Maine↗
USGS1999

Distribution of Trichloroethylene and Geologic Controls on Contaminant Pathways near the Royal River, McKin Superfund Site Area, Gray, Maine

Vapor-diffusion samplers were used in the autumn of 1997 to determine the lateral extent and distribution of concentrations of a trichloroethylene (TCE) plume in the ground-water discharge area near the McKin Superfund Site, Gray, Maine. Analyses of vapor in the samplers identified a plume about 800 feet wide entering the river near Boiling Springs, an area of ground-water discharge on the flood plain of the Royal River. The highest observed concentration of TCE in vapor was in an area of sand boils on the western bank of the river and about 200 feet downstream from Boiling Springs. Previous studies showed that most of the TCE load in the river originated in the area of the sand boils. In general, highest concentrations were observed on the western side of the river on the upgradient side of the plume, but TCE also was detected at numerous locations in the center and eastern bank of the river. The TCE plume discharges to the river where fine-grained glaciomarine sediments of the Presumpscot Formation are absent and where coarse-grained facies of buried glaciomarine fan deposits provide a pathway for ground-water flow. Based on results of analyses of vapor-diffusion samples and other previous studies, the plume appears to pass under and beyond the river near Boiling Springs and along the river for about 300 feet downstream from the sand boils. A coarse-grained, organic-rich layer at the base of the alluvial flood plain sediments is confined by overlying fine-grained alluvial sediments and may provide a conduit for ground-water leaking upward from buried glaciomarine fan deposits.

Water-Resources Investigations Report↗
USGS1997

Hydrogeology, water quality, and simulation of ground-water-development alternatives in the Usquepaug-Queen ground-water reservoir, southern Rhode Island

The Usquepaug-Queen River Basin study describes the hydrogeology, water quality, and simulation of pumping from wells for selected ground-water-development alternatives in the ground-water reservoir under average (1975-90) and drought (1963-66) conditions. In general, ground-water quality is suitable for most purposes. The study provides an evaluation of the effects of simulated pumping of 4 to 11 million gallons per day of ground water on the stream-wetland-aquifer system. Three principal geologic units underlie the Usquepaug-Queen River Basin glacial stratified deposits (stratified drift), glacial till, and crystalline bedrock. Thick and extensive deposits of saturated coarse-grained stratified deposits form the major and most productive aquifer in the Usquepaug-Queen River Basin. The 36.1-square mile Usquepaug-Queen River Basin is in the Pawcatuck River Basin in southern Rhode Island. Stratified deposits cover about 42 percent of the basin and reach a maximum known thickness of 122 feet. The stratified deposits are subdivided into coarse-grained units (dominantly fine to very coarse sand and gravel) and fine-grained units (dominantly very fine sand, silt, and clay). Transmissivity is highest in coarse-grained stratified materials, which have the capability of yielding relatively high volumes of water to wells. Transmissivity is lowest in fine-grained stratified materials, which consist predominantly of lakebottom deposits. Transmissivity of the stratified drift aquifer ranges from 1,900 to 27,800 feet squared per day, and horizontal hydraulic conductivity ranges from 25 to 470 feet per day. The stratified-drift aquifer is the only aquifer in the Usquepaug-Queen River Basin capable of producing yields of 0.5 million gallons per day or more from individual wells. Pumping from ground-water and surface-water sources in the Usquepaug-Queen River Basin averaged 0.28 million gallons per day during 1989 and 0.48 million gallons per day during 1990. Ground water and surface water (which is primarily ground-water runoff) in the UsquepaugQueen River Basin are suitable for most purposes on the basis of a comparison of physical properties and chemical constituents to drinking-water standards. Ground water in the basin is somewhat corrosive because of its low hydrogen-ion concentration. Specific conductance and concentrations of dissolved chloride and dissolved sodium are high in ground water in parts of the Usquepaug-Queen River Basin, which indicates the effects of highway de-icing salts on groundwater quality. Nitrogen (nitrite plus nitrate) concentrations in some localized areas exceed the U.S. Environmental Protection Agency maximum contaminant level of 10 milligrams per liter for drinking water. The effects of selected ground-waterdevelopment alternatives on ground-water levels, wetland-water levels, and streamflow in the Usquepaug-Queen ground-water reservoir were evaluated by means of a three-layer ground-waterflow model. Development alternatives were simulated for average annual (1975-90) and drought (1963-66) conditions. In general, higher simulated pumping rates produced greater drawdowns than lower pumping rates. Drawdowns generally can be reduced by distributing the total pumping over many wells; however, drawdowns were minimal (less than 1.3 feet) in well SNW 906, which was near a major stream (recharge boundary); and drawdowns were substantial (at least 12 feet) in well EXW 33, which was near the edge of the model aquifer boundary (barrier boundary). Total gains in flow from ground-water discharge for all streams in the model area were not affected by the location of wells; however, the amount of ground-water pumpage derived from induced infiltration of streamflow varies significantly. Water levels in the wetlands tend to be constant even during simulated pumping. In general, pumping during simulated drought conditions increased drawdowns fractionally and greatly reduced overall streamflow gains. Pumping from the Usquepaug-Queen stratified-drift aquifer causes infiltration of streamflow along stream segments simulated in the ground-water-flow model. Results of simulations for average conditions show that from 56 to 75 percent of the total water pumped is derived from intercepted ground-water runoff and that the amount of well water derived from induced recharge of streamflow ranged from 20 to 39 percent. The areal extent of contributing areas for selected simulated pumping wells suggest that large areas of stratified drift may need to be protected from land-use practices that are incompatible with the development of potable ground water in the Usquepaug-Queen ground-water reservoir.

Rhode Island↗
USGS1995

Geohydrology of the Gallup's Quarry area, Plainfield, Connecticut

The geohydrology of the Gallup's Quarry area in Plainfield, Connecticut was characterized by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to provide a preliminary framework for future remedial efforts. Gallup's Quarry, an inactive sand and gravel pit, was the site of unregulated disposal of an unknown volume of chemical wastes from at least the summer of 1977 until January 1978. Existing information collected for the Connecticut Department of Environmental Protection during 1978-82 showed that ground water beneath Gallup's Quarry and adjacent land to the northwest was contaminated by organic and inorganic compounds. There is also some evidence for contamination of Mill Brook, which is located north and northwest of the disposal areas. Geologic mapping and subsurface data show that unconsolidated surficial materials up to 90 feet thick overlie fractured crystalline bedrock in most of the Gallup's Quarry area. The surficial materials consist primarily of stratified drift and till. Texture changes vertically and laterally within the stratified drift; grain size ranges from very coarse to fine. Till blankets the bedrock surface beneath the stratified drift and is a few feet to as much as 25 feet thick. Bedrock is exposed at land surface in a hill in the southeastern part of the quarry and slopes to depths of up to 90 feet beneath the area west and north of the disposal sites. The bedrock is a dark, fine-grained, fractured and jointed blastomylonite and hornblende gneiss of the Quinebaug Formation. It is likely that a west- northwest-trending fault is present in the bedrock beneath Gallup's Quarry; this fault, if present, may provide a preferential pathway for ground-water flow and contaminant transport. The principal horizontal direction of ground-water flow and movement of dissolved contaminants in the stratified drift was to the northwest of the waste-disposal areas toward Mill Brook in 1978. Estimates of average annual recharge based on regional analyses for 1978-91 are 30 inches in areas where stratified drift are exposed and 9.6 inches in areas where till and crystalline bedrock are exposed. The hydraulic conductivity of the coarse-grained stratified drift, identified in earlier U.S. Geological Survey studies as part of an aquifer capable of yielding large quantities of water, may be several hundred feet per day. The hydraulic conductivity of the till, based on regional information, is likely 0.04 to 24 feet per day. More detailed geohydrologic information is required to develop effective remedial programs at Gallup's Quarry, particularly in the areas north and west of the waste-disposal areas. Detailed subsurface geologic mapping and definition of head distribution and other hydraulic properties of each geohydrologic unit would indicate directions and rates of ground-water flow. Most importantly, the present extent of contamination of water and sediments throughout the area will have to be determined.

Connecticut↗
USGS1992

Surficial materials map of Connecticut

The unconsolidated deposits overlying bedrock in Connecticut range from a few feet to several hundred feet in thickness. These earth materials significantly affect human development of the land. Most of the unconsolidated materials are deposits of continental glaciers that covered all of New England at least twice during the Pleistocene ice age. These glacial deposits are divided into two broad categories, glacial till and glacial stratified deposits. Till, the most widespread glacial deposit, was laid down directly by glacier ice and is characterized by a nonsorted matrix of sand, silt, and clay with variable amounts of stones and large boulders. Glacial meltwater deposits are concentrated in both small and large valleys· and were laid down by glacial meltwater hi streams and lakes in front of the retreating ice margin during deglaciation. These deposits are characterized by layers of well-sorted to poorly sorted gravel, sand, silt, and clay. Postglacial sediments, primarily floodplain alluvium and swamp deposits, make up a lesser proportion of the unconsolidated materials of Connecticut. Alluvium is largely reworked from glacial materials and has similar physical characteristics.

Connecticut↗
USGS1991

Late Quaternary stratigraphy and depositional history of the Long Island Sound basin

The stratigraphy of Late Quaternary geologic units beneath Long Island Sound (LIS) is interpreted from 3,500 km of high-resolution, seismic-reflection profiles supplemented by vibracore data. Knowledge gained from onshore regional geologic studies and previous offshore investigations is also incorporated in these interpretations. Glacial deposits overlie and nearly fill an Inner Lowland which is floored by crystalline rocks in the north and bounded to the south by an irregular, north-facing cuesta scarp in Cretaceous Coastal-Plain strata. The thick glacial section consists largely of sediment that was deposited in glacial Lake Connecticut during the retreat of the last (late Wisconsin) ice sheet. Ice-marginal lacustrine fan deposits and submerged extensions of the southeastern Connecticut recessional moraines mark positions of the ice margin during systematic northward retreat. When the ice margin stood at positions just north of the present shoreline of Connecticut (17.6-16.5 ka), glacial Lake Connecticut was slightly larger than Long Island Sound is today. Ice-marginal deltas and near-ice marginal fluviodeltaic deposits occur along coastal Connecticut. Delta-building was diachronous; progressively younger deltas record northwesterly retreat of the ice margin and lowering lake levels. Distally from the deltas, varied lake-clays (up to 150 m thick) drape the underlying topography. The lake spillway cut across the Harbor Hill-Roanoke Point-Fishers Island-Charlestown end moraine at its lowest point just west of Fishers Island (The Race). Lake levels fell as the spillway notch was erosionally deepened, and gradually the lakebed became subaerially exposed. A largely preserved channel system cuts the lake-deposit surface; fluvial channel-fill sediments are overlain by estuarine sediments in the channel system. Perhaps as early as 15 ka, but no later than 13 ka, the sea entered the Basin through the channel at The Race and quickly transgressed westward via the lakebed channel system. As the sea rose further and spread throughout the Basin, a wave-cut surface was formed. Extensive marine deltaic deposits, up to 40 m thick, overlie the wave-cut marine unconformity in the east-central part of the Basin. These sediments were derived from erosion of the drained bed of Lake Hitchcock, in the Connecticut valley to the north, and were deposited in a -40-m relative sea at about 12.4 ka. Where quiet waters prevail, marine mud generally less than 15 m thick blankets the older deposits of the Basin. Elsewhere, especially in eastern LIS, tidal currents are actively reworking and transporting glacial and postglacial deposits.

Connecticut, New York↗