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Research about Long Island

Source-linked reports with geographic coverage including Long Island.

At least 91 records · Page 5Linked to original sources
USGS1980

Nitrogen in ground water and surface water from sewered and unsewered areas, Nassau County, Long Island, New York

Data on nitrogen in groundwater and surface waters in the sewered and unsewered parts of Nassau County were analyzed to evaluate the principal sources of nitrogen and to determine what factors significantly affect its concentration in the upper glacial aquifer and the underlying Magothy aquifer. Nitrate data for water samples collected during 1952-76 show that: (1) median nitrate concentration of water in the sewered part of the entire thickness of the upper glacial aquifer is not significantly different (at the 0.95 confidence limit, N = 1400) from that in the unsewered area, (2) median nitrate concentrations in the upper 3 meters of the upper glacial aquifer are significantly lower (at the 0.90 confidence limit, N = 15) in the sewered area than in the unsewered area, (3) in the sewered area, water from 8 of 10 wells in the upper glacial aquifer shows significantly decreasing nitrate concentration with time, (4) total nitrogen concentrations in streams draining the sewered area are significantly lower than in those draining the unsewered area, (5) from more than 2,000 nitrate analyses of water in the Magothy aquifer collected from 1952-76, it was found that nitrate is present at all depths but that nitrate concentrations decrease with depth, and (6) although water from most Magothy wells having long-term nitrate records shows no significant change in nitrate concentration with time, where the change is significant, nitrate is increasing. (USGS)

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USGS1978

Determination of runoff coefficients of storm-water-basin drainage areas on Long Island, New York, by using maximum-stage gages

A method for determining runoff coefficients indirectly without direct measurement of volume of runoff was developed for drainage areas of selected storm-water basins on Long Island, N.Y., to expedite evaluation of basin performance. The method requires a maximum-stage gage to record the maximum water level attained in the basin during the storm, and a precipitation gage to record storm intensity at regular intervals. The maximum volume of runoff impounded in the basin during a storm is calculated from precipitation data, an arbitrarily estimated runoff coefficient, and the basin's dimensions and infiltration rate. The calculated result is then compared with the recorded maximum water level, and the process is repeated with increased or decreased coefficients on a trial basis until two of the resulting water-storage maxima closely bracket the recorded maximum. The runoff coefficient in effect during that storm is then interpolated or derived graphically from the calculated water-storage maxima. Results of data analyses suggest that a close approximation of a basin's infiltration rate may be used instead of a measured infiltration rate to calculate the runoff coefficient. Differences between measured and calculated runoff coefficients averaged less than 20 percent when based on average infiltration rates adjusted for water temperature and less than 10 percent when based on measured infiltration rates. Accuracy of the calculated runoff coefficient tends to decline as the interval between precipitation measurements increases. Precipitation data collected at 5- and 15-minute intervals gave accurate runoff coefficients regardless of storm duration, but data collected at 30- or 60-minute intervals gave widely varying results.

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USGS1977

Leachate plumes in ground water from Babylon and Islip landfills, Long Island, New York

Landfills operated by the Towns of Babylon and Islip in southwest and central Suffolk County contain urban refuse, incinerated garbage, and scavenger (cesspool) waste; some industrial refuse is deposited at the Babylon site. The Islip landfill was started in 1933, the Babylon landfill in 1947. The landfills are in contact with and discharge leachate into the highly permeable upper glacial aquifer (hydraulic conducitvity 190 to 500 ft/d [feet per day]). The aquifer is 74 feet thick at the Babylon landfill and 170 feet thick at the Islip landfill. The leachate-enriched water occupies the entire thickness of the aquifer beneath both landfills, but hydrologic boundaries retard downward migration of the plumes to deeper aquifers. The Babylon plume is 1,900 feet wide at the landfill and narrows to about 700 feet near its terminus 10,000 feet from the landfill. The Islip plume is 1,400 feet wide at the landfill and narrows to 500 feet near its terminus 5,000 feet from the landfill. Hydrochemical maps and sections show the distribution of the major chemical constituents of the plumes. The most highly leachate-enriched ground water obtained was from the Babylon site; it contained 860 mg/L (milligrams per liter) sodium, 110 mg/L potassium, 565 mg/L calcium, 100 mg/L magnesium, 2,700 mg/L bicarbonate, and 1,300 mg/L chloride. Sulfate was notably absent or in low concentration in most parts of both plumes. Nitrogen in plume water was mostly in the form NH4+, and concentrations as high as 90 mg/L were found; concentrations of nitrogen as N in the plume were less than 10 mg/L. As much as 440 mg/L iron and 190 mg/L manganese were found in the leachate-enriched water. Samples were also tested for arsenic, boron, cadmium, cobalt, chromium, copper, mercury, nickel, lead, selenium, strontium, and zinc. Boron was more or less ubiquitous and was found in concentrations as high as 2 mg/L. Organic carbon was found in concentrations as high as 2,250 mg/L in the most highly leachate-enriched water but attenuated rapidly to less than 20 mg/L. Dissolved-solids concentrations near the landfills were between 400 and 3,000 mg/L at Babylon and between 500 and 1,500 mg/L at Islip. Ground-water temperatures near the landfills exceed those in ambient water by as much as 7°C at Babylon and 16°C at Islip. Heat contributed by the landfills was mostly dissipated within 0.4 mi of the landfill, butat Islip, the warm leachate-enriched water extended 0.5 mi downgradient. The entrance of leachate into the less dense ground water as pulsations after rainfall may explain the presence of high leachate enrichment near the bottom of the aquifer. A comparison of the physical characteristics of leachate-enriched ground water with those of ambient water suggests that the downward movement of leachate results from its greater density. Simulation of the movement and dispersion of the Babylon plume with a mathematical dispersion model indicated the coefficient of longitudinal dispersion to be about 60 ft 2 /d (feet squared per day) and the ground-water velocity to be 1 ft/d. However, the velocity determined from the hydraulic gradient and public-supply wells in the area was 4 ft/d, which would cause a plume four times as long as that predicted by the mathmatical dispersion model. At the Islip site, the plume was one-third the length calculated on the basis of the age of the landfill. The shortness of the plumes has not been explained; it may be a result of the leachate's having been too dilute to form a plume during the early years of the landfills.

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USGS1977

Stream simulation in an analog model of the ground-water system on Long Island, New York

The stream circuits of an electric analog model of the ground-water system of Long Island were modified to more accurately represent the relationahip between streamflow and ground-water levels. Assumptions for use of the revised circuits are (1) that streams are strictly gaining, and (2) that ground-water seepage into the streams is proportional to the difference between streambed elevation and the average water-table elevation near the stream. No seepage into streams occurs when ground-water levels drop below the streambed elevation. Regional simulation of the 1962-68 drought on Long Island was significantly improved by use of the revised stream circuits.

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USGS1977

Analysis of the recharge potential of storm-water basins on Long Island, New York

Many of the more than 2,200 storm-water basins on Long Island, N.Y., are potential sites for infiltration of large volumes of reclaimed water (highly treated domestic and industrial sewage). By use of a finite-difference method of calculation, changes in basin storage during idealized high-intensity storms were determined for the North Massapequa basin, a typical basin on Long Island. Calculations for a 100- year storm, in which a runoff coefficient of 20 percent was used but in which infiltration rate, storm intensity, storm duration, and return period were varied, indicate that this test basin would not overflow even if the infiltration rate declined from its present 1.5 feet per hour (0.46 meter per hour) to about 0.03 ft/h (0.009 m/h). The large reserve capacity of the test basin and similar basins on Long Island demonstrates the feasibility of using storm-water basins for infiltration of a supplemental water supply (supplemental recharge). If reclaimed water were ponded to a depth of 4 ft (1.2 m) in the test basin and if water application were alternated for equal periods between the test basin and a nearby basin with similar characteristics, the volume of infiltration would be slightly more than two million gallons per day (0.09 cubic meters per second) at an infiltration rate of 1.5 ft/h (0.46 m/h). With supplemental recharge, 60 percent of available storage capacity would be used during a 10-yr storm, and 80 percent would be used during a 100-yr storm, using a runoff coefficient of 20 percent.

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USGS1976

Evaluation of hydrologic properties of the Long Island ground-water reservoir using cross-sectional electric-analog models

Variables necessary for constructing a quantitative model to predict the response of ground-water reservoirs to hydrologic stresses are in four classes: (a) external and internal geometry of the reservoir, (b) nature of the reservoir boundaries, (c) areal distribution of horizontal and vertical hydraulic conductivities, and (d) areal distribution of storage capability within the reservoir. In this report, the sensitivity of the Long Island ground-water reservoir's reponse to the first three of these variables was evaluated using analog models.

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USGS1973

Flow characteristics of a subsurface-controlled recharge basin on Long Island, New York

Ponding studies at the Woodbury recharge basin on Long Island, N.Y., show that the principal zones controlling infiltration are a surface-loam stratum and an intermediate gravelly, sandy loam stratum. The saturated hydraulic conductivities of these strata are 0.90 and 0.1 ft per day, respectively. The surface loam acts as the principal zone controlling infiltration until a perched ground-water mound develops above the intermediate gravelly, sandy loam and extends to the bottom of the surface loam; then the intermediate gravelly, sandy loam becomes the principal infiltration controlling zone. Infiltration rates at 15.6° Celsius are 1.4 ft per day when the surface loam is acting as the principal controlling zone and 0.5 ft per day when the intermediate gravelly, sandy loam is acting as the principal controlling zone. Projections of the probable infiltration rates associated with both the partial and the complete removal of the surface-loam stratum show that if recharge continues for several days total infiltration would not be greatly different whether or not the loam stratum is completely removed. The principal advantage of completely removing the surface-loam stratum is the resulting greater infiltration capacity during the early stages of ponding. This advantage is offset by potential problems associated with more intensive clogging of the subsurface controlling zone.

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USGS1971

Water table in Long Island, New York, March 1971

The geologic framework and the hydrologic situation in Long Island are periodically reviewed by the U.S. Geological Survey as new knowledge is obtained from current investigations. This work is done through cooperative programs with Nassau and Suffolk County agencies and the New York State Department of Environmental Conservation. A unique opportunity to update many of the hydrogeologic maps occurred when the Geological Survey's Mineola, N.Y., office participated in the New England River Basins Commission's "Long Island Sound Study." This map, one of a series of open-file maps showing the updated information, was compiled from data obtained from G. E. Kimmel (written commun., July 1972) and Jensen and Soren (in press). Comparison of the March 1971 data with similar data for March 1970 (Kimmel, 1970) shows virtually no change in water levels on Long Island during the 12 month period, except for a slight decline in levels in central Suffolk County.

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USGS1963

Geology and ground-water conditions in southern Nassau and southeastern Queens Counties, Long Island, N.Y.

Test drilling, electrical logging, and water sampling of 'outpost' and other wells have revealed the existence of a deep confined body of salt water in the Magothy(?) formation beneath southwestern Nassau and southeastern Queens Counties, Long Island, N.Y. In connection with a test-drilling program, cooperatively sponsored by the U.S. Geological Survey, the Nassau County Department of Public Works, and the New York State Water Resources Commission (formerly Water Power and Control Commission), 13 wells ranging in depth from about 130 to 800 feet were drilled during 1952 and 1953 and screened at various depths in the Magothy(?) formation and Jameco gravel. On the basis of the preliminary geologic, hydrologic, and chemical data from these wells, a detailed investigation of ground-water conditions from the water table to the bedrock was begun in a 200-square-mile area in southern Nassau and southeastern Queens Counties. The Inain purposes of the investigation were to delineate the bodies of fresh and salty ground water in the project area, to relate their occurrence and movement to geologic and hydrologic conditions, to estimate the rate of encroachment, if any, of the salty water, and to evaluate the effectiveness of the existing network of outpost wells as detectors of salt-water encroachment. About a million people in the report area, residing mainly in southern Nassau County, are completely dependent on ground water as a source of supply. Fortunately, precipitation averages about 44 inches per year, of which approximately half is estimated to percolate into the ground-water reservoir. The ground water is contained in and moves through eight differentiated geologic units composed of unconsolidated gravel, sand, and clay, of Late Cretaceous, Pleistocene, and Recent age, having a maximum total thickness of about 1,700 feet. The underlying metamorphic and igneous crystalline basement rocks are of Precambrian age and are not water bearing. The water-yielding units from the surface down are (1) the upper Pleistocene deposits, (2) the principal artesian aquifer, composed of the Jameco gravel and Magothy(?) formation, and (3) the Lloyd sand member of the Raritar formation. The confining units are the '20-foot' clay, the Gardiners clay, and the clay member of the Raritan formation. The upper Pleistocene deposits contain an extensive unconfined body of fresh water. Fresh water under artesian conditions is contained in the principal artesian aquifer and the Lloyd sand member. The piezometric surface of the principal artesian aquifer is similar in shape to the south-ward-sloping water table; it ranges in altitude from about sea level to 55 feet above. The chemical quality of the fresh ground water in most of the area in all aquifers is good to excellent, and concentrations of dissolved solids and of chloride generally are below 100 ppm (parts per million) and 10 ppm, respectively. Analyses of water samples from selected wells show no progressive increase in concentration of chloride in most of the area. The data on quality of water have been used to delineate one major and several minor bodies of salty ground water. The wedgeshaped main confined salt-water body, in which the concentration of chloride reaches about 17,000 ppm, is in the Magothy(?) formation and Jameco gravel in extreme southwestern Nassau County and southeastern Queens County. The base of the salt-water wedge is about at the top of the clay member of the Raritan formation. Beneath the barrier beach in south-central and southeastern Nassau County a shallow extension of the main confined salt-water body contains as much as 4,000 ppm of chloride and is separated from the lower main salt-water body by fresh ground water. Shallow, thin bodies of unconfined salty ground water are common in the upper Pleistocene and Recent deposits adjacent to salty surface water in tidal creeks, bays, and the Atlantic

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USGS1960

Position of the salt-water body in the magothy(?) formation in the Cedarhurst-Woodmere area of southwestern Nassau county, Long Island, N.Y.

The position and chloride concentration of a sizable body of salt water , moving slowly landsyard from the south-shore bays of Long Island and the Atlantic Ocean were defined by recent test drilling in the Cedarhurst-Woodmere area of southwestern Nassau County, Long Island, N. Most of the salt-water body is in the lower part of a permeable artesian aquifer; the lowermost part of the salt-water body is in clay deposits underlying the permeable aquifer. The upper limit of the salt-water body in this area was found at depths increasing progressively in a landward direction. It was 318 feet below sea level at a well in Cedarhurst and 541 feet below sea level at a well in Woodmere. The lower limit of the salt-water body was determined at depths between 578 and 630 feet below sea level in the Cedarhurst-Woodmere area. The salt-water body is more than 300 feet thick at a well in Cedarhurst, and it thins out to zero in the vicinity of a pumping center about 1- miles northeast of the Cedarhurst well. Chloride concentration in the salt-water body in the Cedarhurst-Woodmere area ranged from about 40 to 16,000 ppm (parts per million). Isochlors define a zone of diffusion about a mile wide in the Cedarhurst-Woodmere area. They indicate a thickness of diffused water ranging from a few tens to more than 150 feet vertically. Electrical-log data show that the upper boundary of the salt-water body moved upward 21 feet between 1952 and 1958 at a site in Woodmere about half a mile southwest of the pumping center. ' From this information it is inferred that between 1952 and 1958 the leading edge of the saltwater front moved landward about 2,000 feet toward the pumping center.

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USGS1959

The relation between fresh and salty ground water in southern Nassau and southeastern Queens counties, Long Island, New York

An investigation of the geology and ground - water conditions in a part of southwestern Long Island , including the construction of 8 deep and 5 shallow test and observation wells, has been completed by the Geological Survey in cooperation with the Nassau County Department of Public Works and the New York State Water Power and Control Commission. In this area are four main water -bearing units of Late Cretaceous and Pleistocene age. Ground water having a higher than normal salt content is encountered in some wells that penetrate the upper three units. Although the presence of this water constitutes a potential threat, existing fresh - water supplies apparently are in little immediate danger under present conditions. The " salty " ground water has chloride concentrations ranging from about 40 to 18,000 ppm (parts per million), generally more than about 2,000 ppm. It occurs in several bodies, seaward of and beneath the fresh water in the respective aquifers, and is in contact with the fresh water through zones of diffusion. The largest salt- water body, confined under artesian pressure, is in the Jameco gravel and the Magothy (?) formation beneath extreme southwestern Nassau County and adjoining southeastern Queens County . This body is thought to have occupied a substantial part of its present extent since at least 1895. It probably has been and is now encroaching, very slowly, because of increased pumping from the fresh - water bodies and possibly as a result of a postglacial rise of sea level. The rate of encroachment under present conditions probably is less than 100 feet per year. Application of the Ghyben-Herzberg principle to compute depths to the contact between salty and fresh ground water was found to give erroneous results. More accurate depths and a clearer understanding of the relation between heads in adjoining bodies of fresh and salty ground water are obtained by use of a formula adapted from one given by M. King Hubbert.

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