USGS Science⌕ Search

SEARCH · USGS Science

Results for “Pennsylvania Geology”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
USGS1993

Water-resources investigations in Pennsylvania; programs and activities of the U.S. Geological Survey, 1993

Current activities of the Pennsylvania District of the USGS are described and include information on current projects, such as project objectives, approach, progress and plans, project location, cooperators, period of project, and project chief. Basic-data programs for surface water, ground water, and quality of water also are described. Also included is information on the basic mission and programs of the USGS; program funding and cooperation for fiscal year 1993; the USGS water- data program, National Water-Data Exchange, and National Water-Data Storage and Retrieval System; and Pennsylvania data-collection programs and hydrologic investigations. List of publications of the Pennsylvania District and maps published by the USGS, as well as information on how to obtain them, are included.

Open-File Report↗
USGS1984

Compilation of ground water quality data in Pennsylvania

The U.S. Geological Survey's water quality file of 4,671 wells and springs in Pennsylvania provided ground-water-quality data for Pennsylvania. The data were assembled into computer-readable format and sorted into 15 major aquifer groups based on principal lithology, physiographic province, and age. Nineteen variables in each group were summarized by the Statistical Analysis Systems UNIVARIATE procedures to produce descriptive statistics including extreme values and quartiles. The bulk of the water-quality data are in the important aquifers in the unconsolidated Coastal Plain sediments, the Triassic sedimentary rocks, the igneous and metamorphic rocks, and the carbonate rocks. On the other hand, water-quality data for aquifer groups in the Appalachian Plateau and Valley and Ridge Province are sparse. Statewide, only six wells provide sufficient long-term data for trend analyses. Ground-water quality in Pennsylvania is highly diverse. High concentrations of dissolved solids, iron, manganese, sulfate, and nitrate are prevalent forms of natural and manmade contamination. The unconsolidated Coastal Plain aquifers have been most severely degraded. On the other hand, some of the best quality water is found in the quartzite, sandstone, and conglomerate rock units in the Cambrian and Precambrian rocks.

Open-File Report↗
USGS2008

Spatial Distribution of Ground-Water Recharge Estimated with a Water-Budget Method for the Jordan Creek Watershed, Lehigh County, Pennsylvania

This report presents the results of a study by the U.S. Geological Survey, in cooperation with the Pennsylvania Geological Survey, to illustrate a water-budget method for mapping the spatial distribution of ground-water recharge for a 76-square-mile part of the Jordan Creek watershed, northwest of Allentown, in Lehigh County, Pennsylvania. Recharge was estimated by using the Hydrological Evaluation of Landfill Performance (HELP) water-budget model for 577 landscape units in Jordan Creek watershed, delineated on the basis of their soils, land use/land cover, and mean annual precipitation during 1951-2000. The water-budget model routes precipitation falling on each landscape unit to components of evapotranspiration, surface runoff, storage, and vertical percolation (recharge) for a five-layer soil column on a daily basis. The spatial distribution of mean annual recharge during 1951-2000 for each landscape unit was mapped by the use of a geographic information system. Recharge simulated by the water-budget model in Jordan Creek watershed during 1951-2000 averaged 12.3 inches per year and ranged by landscape unit from 0.11 to 17.05 inches per year. Mean annual recharge during 1951-2000 simulated by the water-budget model was most sensitive to changes to input values for precipitation and runoff-curve number. Mean annual recharge values for the crop, forest, pasture, and low-density urban land-use/land-cover classes were similar (11.2 to 12.2 inches per year) but were substantially less for high-density urban (6.8 inches per year), herbaceous wetlands (2.5 inches per year), and forested wetlands (1.3 inches per year). Recharge rates simulated for the crop, forest, pasture, and low-density urban land-cover classes were similar because those land-use/land-cover classes are represented in the model with parameter values that either did not significantly affect simulated recharge or tended to have offsetting effects on recharge. For example, for landscapes with forest land cover, values of runoff-curve number assigned to the model were smaller than for other land-use/land-cover classes (causing more recharge and less runoff), but the maximum depth of evapotranspiration was larger than for other land-use/ land-cover classes because of deeper root penetration in forests (causing more evapotranspiration and less recharge). The smaller simulated recharge for high-density urban and wetland land-use/land-cover classes was caused by the large values of runoff-curve number (greater than 90) assigned to those classes. The large runoff-curve number, however, certainly is not realistic for all wetlands; some wetlands act as areas of ground-water discharge and some as areas of recharge. Simulated mean annual recharge computed by the water-budget model for the 53-square-mile part of the watershed upstream from the streamflow-gaging station near Schnecksville was compared to estimates of recharge and base flow determined by analysis of streamflow records from 1967 to 2000. The mean annual recharge of 12.4 inches per year simulated by the water-budget method for 1967-2000 was less than estimates of mean annual recharge of 19.3 inches per year computed from the RORA computer program and base flow computed by the PART computer program (15.1 inches per year). In theory, the water-budget method provides a practical tool for estimating differences in recharge at local scales of interest, and the watershed- average recharge rate of 12.4 inches per year computed by the method is reasonable. However, the mean annual surface runoff of 4.5 inches per year simulated by the model is unrealistically small. The sum of surface runoff and recharge simulated by the water-budget model (16.9 inches per year) is 7 inches per year less than the streamflow measured at the gaging station near Schnecksville (23.9 inches per year) during 1967-2000, indicating that evapotranspiration is overestimated by the water-budget model by that amount. This discrepancy ca

Scientific Investigations Report↗
USGS1998

U.S. Geological Survey cooperative water-resources programs in Chester County, Pennsylvania

Since 1969, the U.S. Geological Survey (USGS) has had a cooperative water-resources investigation program with Chester County to measure and describe the water resources of the County. Generally, the USGS provides one-half of the program funding, and local cooperators are required to provide matching funds. Cooperation has been primarily with the Chester County Water Resources Authority (CCWRA), with participation from the Chester County Health Department and funding from the Chester County Board of Commissioners. Municipalities and the Red Clay Valley Association also have provided part of the funding for several projects. This report describes how the long-term partnership between the USGS and Chester County, Pa., provides the County with the information that it needs for sound water-resources management. The CCWRA was created in 1961, primarily for land acquisition and planning for flood-control and water-supply projects. With the backing of the Brandywine Valley Association, the CCWRA started its first cooperative project with the USGS in 1969. It was a study of the water-quality condition of Chester County streams with an emphasis on benthic macroinvertebrates and stream chemistry. The kinds of projects and data collection conducted by the USGS have changed with the needs of Chester County and the mission of the CCWRA. Chester County is experiencing rapid population growth (it had the tenth-highest rate of growth in the nation from 1980 to 1990). This growth places considerable stress on water resources and has caused the CCWRA to broaden its focus from flood control to water-supply planning, water quality, and ground-water and surface-water management. The results of USGS studies are used by the CCWRA and other County agencies, including the Planning Commission, Health Department, and Parks and Recreation Department, for conducting day-to-day activities and planning for future growth. The results also are used by the CCWRA to provide guidance and technical assistance to municipalities, water suppliers, industrial dischargers, watershed and conservancy associations and other civic organizations, state and Federal agencies, river basin commissions, and the private sector. The cooperative water-resources program, which is described in the following sections, benefits not only the citizens of Chester County but also serves the interests of the Federal Government. Innovative studies conducted in Chester County provide methods and interpretations that often can be used nationwide, and the headwaters of several interstate drainages lie within the County. Major program thrusts include collection of surface-water, ground-water, and water-quality data and interpretive studies. The use of this information also is described.

Pennsylvania↗
USGS1997

Evaluation of agricultural best-management practices in the Conestoga River headwaters, Pennsylvania: Effects of nutrient management on quality of surface runoff and ground water at a small carbonate-rock site near Ephrata, Pennsylvania, 1984-90

The U.S. Geological Survey and the Pennsylvania Department of Environmental Protection conducted a study from 1984 to 1990 to determine theeffects of the implementation and practice of nutrient management [an agricultural best-management practice (BMP)] on the quality of surface runoff and ground water at a 55-acre crop and livestock farm in carbonate terrain nearEphrata, Pa. Implementation of nutrient management at Field-Site 2 resulted in application decreases of 33 percent for nitrogen and 29 percent for phosphorus. There wereno significant changes in nitrogen or phosphorusloads for a given amount of runoff from the pre-BMP to the post-BMP periods. However, less than 2 percent of the applied nutrients weredischarged with runoff throughout the study period.After the implementation of nutrient management, statistically significant decreases in concentrations of nitrate in ground-water samples occurred at threeof the four wells monitored throughout the pre- and post-BMP periods. The largest decreases in nitrate concentrations occurred at wells where samples hadthe largest nitrate concentrations prior to nutrient management. Changes in nitrogen applications to the contributing areas of five wells were correlated with nitrate concentrations of the well water. The correlations between the timing and amount of applied nitrogen and changes in ground-water quality met the four conditions that are characteristic of a cause-effect relation: an association, consistency, responsiveness, and a mechanism. Changes in ground-water nitrate concentrations lagged behind changes in loading of nitrogen fertilizers (primarily manure) by approximately 4 to 19 months.

Pennsylvania↗
USGS2011

An innovative method for nondestructive analysis of cast iron artifacts at Hopewell Furnace National Historic Site, Pennsylvania

The U.S. Geological Survey (USGS) is conducting research at Hopewell Furnace National Historic Site (fig. 1; see sidebar, page 53) in southeastern Pennsylvania to determine the fate of trace metals, such as arsenic, cobalt, and lead, released into the environment during the iron-smelting process. Arsenic is a carcinogen, cobalt is a suspected carcinogen, and lead can cause severe health problems. Iron ore containing elevated quantities of trace metals was smelted at Hopewell Furnace during its 113 years of operation (1771-1883). The ore used at Hopewell Furnace was obtained from local mines, mainly the Jones and Hopewell mines, which were within 5 miles (8 km) of the furnace. The iron ore deposits were formed during the early Jurassic period about 200 million years ago. The deposits are mineralogically similar and contain abundant magnetite, the chief iron mineral, and accessory minerals enriched in arsenic, cobalt, copper, and other metals.

Pennsylvania↗
USGS2009

Water-quality monitoring in response to young-of-the-year smallmouth bass (Micropterus dolomieu) mortality in the Susquehanna River and major tributaries, Pennsylvania: 2008

Mortalities of young-of-the-year (YOY) smallmouth bass ( Micropterus dolomieu ) recently have occurred in the Susquehanna River due to Flavobacterium columnare , a bacterium that typically infects stressed fish. Stress factors include but are not limited to elevated water temperature and low dissolved oxygen during times critical for survival and development of smallmouth bass (May 1 through July 31). The infections were first discovered in the Susquehanna River and major tributaries in the summer months of 2005 but also were prevalent in 2007. The U.S. Geological Survey, Pennsylvania Fish and Boat Commission, Pennsylvania Department of Environmental Protection, and PPL Corporation worked together to monitor dissolved oxygen, water temperature, pH, and specific conductance on a continuous basis at seven locations from May through mid October 2008. In addition, nutrient concentrations, which may affect dissolved-oxygen concentrations, were measured once in water and streambed sediment at 25 locations. Data from water-quality meters (sondes) deployed as pairs showed daily minimum dissolved-oxygen concentration at YOY smallmouth-bass microhabitats in the Susquehanna River at Clemson Island and the Juniata River at Howe Township Park were significantly lower (p-value < 0.0001) than nearby main-channel habitats. The average daily minimum dissolved-oxygen concentration during the critical period (May 1–July 31) was 1.1 mg/L lower in the Susquehanna River microhabitat and 0.3 mg/L lower in the Juniata River. Daily minimum dissolved-oxygen concentrations were lower than the applicable national criterion (5.0 mg/L) in microhabitat in the Susquehanna River at Clemson Island on 31 days (of 92 days in the critical period) compared to no days in the corresponding main-channel habitat. In the Juniata River, daily minimum dissolved-oxygen concentration in the microhabitat was lower than 5.0 mg/L on 20 days compared to only 5 days in the main-channel habitat. The maximum time periods that dissolved oxygen was less than 5.0 mg/L in microhabitats of the Susquehanna and Juniata Rivers were 8.5 and 5.5 hours, respectively. Dissolved-oxygen concentrations lower than the national criterion generally occurred during nighttime and early-morning hours between midnight and 0800. The lowest instantaneous dissolved-oxygen concentrations measured in microhabitats during the critical period were 3.3 mg/L for the Susquehanna River at Clemson Island (June 11, 2008) and 4.1 mg/L for the Juniata River at Howe Township Park (July 22, 2008). Comparison of 2008 data to available continuous-monitoring data from 1974 to 1979 in the Susquehanna River at Harrisburg, Pa., indicates the critical period of 2008 had an average daily mean dissolved-oxygen concentration that was 1.1 mg/L lower (p-value < 0.0001) than in the 1970s and an average daily mean water temperature that was 0.8 °C warmer (p-value = 0.0056). Streamflow was not significantly different (p-value = 0.0952) between the two time periods indicating that it is not a likely explanation for the differences in water quality. During the critical period in 2008, dissolved-oxygen concentrations were lower in the Susquehanna River at Harrisburg, Pa., than in the Delaware River at Trenton, N.J., or Allegheny River at Acmetonia near Pittsburgh, Pa. Daily minimum dissolved-oxygen concentrations were below the national criterion of 5.0 mg/L on 6 days during the critical period in the Susquehanna River at Harrisburg compared to no days in the Delaware River at Trenton and the Allegheny River at Acmetonia. Average daily mean water temperature in the Susquehanna River at Harrisburg was 1.8 °C warmer than in the Delaware River at Trenton and 3.4 °C warmer than in the Allegheny River at Acmetonia. These results indicate that any stress induced by dissolved oxygen or other environmental conditions is likely to be magnified by elevated temperature in the Susquehanna River at Harrisburg compared to the Delaware River at Trenton or the Allegheny River at Acmetonia.

Pennsylvania↗
USGS2026

Data-collection methods for total dissolved gases monitoring, Youghiogheny River at Dam Outlet Tunnel near Confluence, Pennsylvania

Supersaturation of total dissolved gases (TDG) can potentially occur in the tailrace water at the Youghiogheny River at dam outlet tunnel near Confluence, Pennsylvania (U.S. Geological Survey [USGS] streamgaging and monitoring station 03077100). The USGS, in cooperation with the U.S. Army Corps of Engineers, established methods to collect and report TDG saturation data in the tailrace below the Youghiogheny Dam. Monitoring and TDG data collection started in June 2008 and continues currently (2025). Data are collected from June 1 through November 30 of each year, and these data are used by the U.S. Army Corps of Engineers to guide management of the dam outflow. Methods used for data collection, processing, reporting, and quality assurance for TDG monitored at USGS station 03077100 are presented in this report. The TDG data are publicly available in the USGS National Water Information System database.

Pennsylvania↗
USGS1989

A direct correlation among indoor Rn, soil gas Rn and geology in the Reading Prong near Boyertown, Pennsylvania

We feel that this study suggests a relationship among geology, soil gas Rn and the potential for indoor Rn accumulation in this portion of the Reading Prong. There are deviations from a perfect correlation but these are related to inhomogeneities in the geologic environment and perhaps variations in construction techniques of homes in the area. This study also demonstrates that several analyses in a small area may be necessary to adequately determine the Rn distribution for a particular geologic unit. That scale would be determined by the complexity of the local geology. Where no discrete source of elevated Rn supply is found for dwellings having a significant Rn accumulation, the implication is that overall gross permeability may be sufficient to supply Rn from a larger volume of soil and rock.

Health Physics↗
USGS1998

Preliminary results from the investigation of the Pymatuning earthquake of September 25, 1998

The Pymatuning earthquake occurred on Friday, September 25, 1998, at 19:52:52 Universal Coordinated Time (UTC), or 3:52:52 p.m. EDT, near Jamestown, Pa., at the southern end of the Pymatuning Reservoir, which straddles the Ohio-Pennsylvania border. The National Earthquake Information Center (NEIC) determined that the event had a magnitude of 5.2 mbLg (a magnitude scale used to measure the size of earthquakes that are regional distances away [100 to 1,000 km, or 60 to 600 mi]), an epicenter of 41.5°N latitude, 80.4°W longitude, and an estimated depth of 5 km (3 mi). One person was reported injured as a result of being thrown to the ground by the earthquake, and it caused minor damage to buildings and seriously disrupted many water wells in the GreenvilleJamestown, Pa., area. The earthquake was generally felt over an area of approximately 200,000 km 2 (77,230 mi 2 ) throughout northern Ohio, western Pennsylvania and New York, and much of southern Ontario, Canada (see map on back cover). It was also felt as far west as Illinois and Wisconsin, as far east as New Jersey, Connecticut, and the District of Columbia, and as far south as Kentucky and Virginia. During the aftershock field investigation that commenced within 12 hours of the main shock, a World Wide Web site, < http://groundmotion.cr.usgs.gov/pym/pym.htm >, was established from the field headquarters. The web site was used not only to transmit investigation results to the world in near real time but also to receive information from the local community as new earthquake effects were reported. As of March 1999, at least 11 aftershocks have occurred, the largest being a magnitude 2.3. The largest recent previous earthquake in the region was the northeastern Ohio (Leroy) earthquake of magnitude 5.0 that occurred on January 31, 1986, about 65 km (40 mi) west-northwest of the Pymatuning shock. This event was also felt by many of those who felt the Pymatuning earthquake. Similar to most of the seismicity east of the Rocky Mountains, earthquakes in the region are probably shallow (5 to 10 km, or 3 to 6 mi), and Seeber and Armbruster (1993) hypothesized that the earthquakes occurred along preexisting zones of weakness in Precambrian rocks. Wegweiser and others (1998) suggested that seismicity in northwestern Pennsylvania may be associated with the northwest-trending “cross-strike discontinuities” that are recognized in Paleozoic rocks and may represent reactivation of faults in the Precambrian basement. Using structure-contour maps constructed on the tops of lower Paleozoic strata, Alexandrowicz and Cole (1999) found evidence of preexisting northwest-striking faults in the epicentral region of the Pymatuning shock. The Harvard focal mechanism for the Pymatuning earthquake (a method used to infer the slip and orientation of the fault that generated an earthquake) indicates thrust faulting on a northwest striking plane, which is consistent with the regional northeast-southwest compressive stress regime observed in the area. Seeber and Armbruster (1993) plotted three prior earthquakes in the epicentral area having magnitudes greater than 3; two were instrumentally located near the Pymatuning earthquake, and the third event occurred 20 to 30 km (12 to 19 mi) to the northeast in 1852 (Figure 1).

Connecticut;District of Columbia;Illinois;Kentucky↗
USGS2013

Geohydrologic and water-quality characterization of a fractured-bedrock test hole in an area of Marcellus shale gas development, Bradford County, Pennsylvania

Open-File Miscellaneous Investigation 13–01.1 presents the results of geohydrologic investigations on a 1,664-foot-deep core hole drilled in the Bradford County part of the Gleason 7.5-minute quadrangle in north-central Pennsylvania. In the text, the authors discuss their methods of investigation, summarize physical and analytical results, and place those results in context. Four appendices include (1) a full description of the core in an Excel worksheet; (2) water-quality and core-isotope analytical results in Excel workbooks; (3) geophysical logs in LAS and PDF files, and an Excel workbook containing attitudes of bedding and fractures calculated from televiewer logs; and (4) MP4 clips from the downhole video at selected horizons.

Pennsylvania↗
USGS2015

Continuous monitoring of meteorological conditions and movement of a deep-seated, persistently moving rockslide along Interstate Route 79 near Pittsburgh

A large inventory of landslides exists for Allegheny County, Pa., and historical movement of many of these has resulted in considerable damage to property, roads, and infrastructure. Along Interstate Route 79, a subset of the landslide inventory includes deep-seated rockslides, two of which reactivated during construction of the highway in the late 1960s (Gray and others, 2011). Following the initial movement of the rockslides, slope-stability investigations were conducted (Hamel, 1969; Hamel and Flint, 1969), and measures were taken to reduce their impacts to the highway, but movement of at least one of the rockslides persists even today. Long-term continuous monitoring of such landslides provides critical data used to assess how the state of activity and velocity of movement (when the landslide is active) change with rainfall and snowmelt. Currently, we are continuously monitoring meteorological conditions and movement of a rockslide along the northbound side of Interstate Route 79 in Aleppo, Pa. (Figure 1). The project is intended to extend over many years (approximately 5 to 10) in order to collect sufficient data to assess how extreme storms, prolonged wet periods, and melting of the snowpack affect the landslide. The rockslide is an ideal location for such long-term monitoring because the land is owned by the Pennsylvania Department of Transportation (PennDOT), and movement is not directly impacting the highway; therefore no stabilization measures are necessary in the short term.

Pennsylvania↗
USGS2024

Results of 2018–19 water-quality and hydraulic characterization of aquifer intervals using packer tests and preliminary geophysical-log correlations for selected boreholes at and near the former Naval Air Warfare Center Warminster, Bucks County, Pennsylvania

The U.S. Geological Survey (USGS) collected data on the vertical distribution of hydraulic head, specific capacity, and water quality using aquifer-interval-isolation tests and other vertical profiling methods in 15 boreholes completed in fractured sedimentary bedrock in Northampton, Warminster, and Warwick Townships, Bucks County, Pennsylvania during 2018–19. This work was done, in cooperation with the U.S. Navy, to support detailed investigations at and near the former Naval Air Warfare Center (NAWC) Warminster, where groundwater contamination with per- and polyfluoroalkyl substances (PFAS) had become a concern since 2014. Two PFAS compounds, perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), have been measured in groundwater samples from supply and monitoring wells at or near NAWC Warminster in concentrations above U.S. Environmental Protection Agency health advisory levels for drinking water. The area is underlain by the Triassic Stockton Formation, which predominantly consists of sandstone interbedded with shale and siltstone beds and forms a layered fractured-rock aquifer used for private, industrial, and public drinking water supply. The vertical distribution of aquifer properties and water quality was assessed through hydraulic tests and sampling of aquifer intervals using a straddle-packer system (13 boreholes) or depth-discrete point sampling under known borehole-flow conditions (2 boreholes). Geophysical and video logs collected by USGS during 2017–19 were used to identify potential water-bearing fractures in 15 boreholes, which ranged in depth from 210 to 604 feet (ft) and included 6 boreholes drilled in 2018 and 9 existing wells on or near the former NAWC Warminster. Measured borehole flow was predominantly downward in most of the deepest boreholes (greater than 400 ft), which were commonly located at the highest land-surface elevations, with inflow from fractures at relatively shallow depths and outflow through fractures near or below depths of 500 ft below land surface. Hydraulic head differences measured during packer tests were up to about 60 ft between shallow and deep intervals. Borehole flow was predominantly upward in most boreholes less than 400 ft in depth and farther from, and at lower land-surface elevations than, the former NAWC Warminster. Total borehole specific capacity ranged from about 0.07 to 41 gallons per minute per foot [(gal/min)/ft]. Specific-capacity values for individual intervals ranged from 0.02 to 40.0 (gal/min)/ft, with a median of 1.14 (gal/min)/ft and a large range in values at most depths. Differences in water quality of samples as indicated by field properties (pH, dissolved oxygen, and specific conductance) and concentrations of dissolved major ions, PFOA, and PFOS were apparent among isolated intervals in the boreholes. Summed concentrations of PFOA and PFOS ranged from about 11 to 10,780 nanograms per liter (ng/L) and were greater than the 2016 U.S. Environmental Protection Agency health advisory of 70 ng/L for summed PFOA and PFOS concentrations in 62 of 104 intervals and discrete depths tested. The mass ratio of PFOS to PFOA was generally higher than 1.0 in samples with summed PFOA and PFOS concentrations greater than 70 ng/L, with ratio values as high as 8.7. In many boreholes, summed concentrations of PFOA and PFOS were positively related to chloride concentrations, which were elevated above natural-background values [less than 10 milligrams per liter] in most samples and as high as 717 milligrams per liter. Sources of the elevated chloride other than, or in addition to, common rock salt (sodium chloride) were indicated by chloride to sodium molar ratios greater than 1.0. Water-quality data indicated that sampled water from some intervals with lower hydraulic heads may be affected by water from intervals with higher hydraulic heads because of vertical flow in open boreholes; samples from these intervals with lower hydraulic heads may not be fully representative due to some component of cross contamination and should be interpreted with caution. Through a preliminary correlation of natural gamma and resistivity logs of boreholes drilled at and near the former NAWC Warminster, 11 lithologic units were identified and interpreted to strike northeast and dip to the northwest. Hydraulic heads were generally highest in isolated intervals that intercepted beds which, when projected up dip, crop out at the highest land-surface elevation on the former NAWC Warminster, indicating that the dipping-bed structure and topography are factors affecting the distribution of hydraulic head in the aquifer. The hydrogeologic framework in conjunction with the vertical distribution of hydraulic heads and water quality may assist in evaluating the locations of various PFAS sources and potential migration pathways of PFAS in groundwater at and near NAWC Warminster.

Pennsylvania↗
USGS2024

Hydrologic investigations and a preliminary conceptual model of the groundwater system at North Penn Area 1 Superfund Site, Souderton, Montgomery County, Pennsylvania

The U.S. Geological Survey (USGS) conducted hydrogeologic investigations, reviewed existing data, and developed a preliminary conceptual model of the groundwater system as part of technical support of the U.S. Environmental Protection Agency (EPA) at the North Penn Area 1 Superfund Site (hereafter, the NP1 Site) located within the Borough of Souderton in Montgomery County, Pennsylvania. Field work and monitoring took place during 2012–18. The area is underlain by sedimentary formations that form a fractured-rock aquifer used for drinking water and industrial supply. The EPA placed the Site on the National Priorities List in 1989, identifying tetrachloroethylene (PCE) and trichloroethylene (TCE) as contaminants of concern. During 2012–18, the USGS conducted field activities that included drilling an 82-foot (ft)-deep monitoring well (MG 2220) in 2016, reconstructing a 208-ft-deep former industrial production well (MG 668 [Granite Knitting Mill]), and collecting borehole geophysical and video logs and water levels from those and five additional wells, which ranged in depth from about 50 to 200 ft below land surface. Continuous water levels were collected during 2014–17, and a synoptic set of water levels were measured in April 2018 in the seven wells. The borehole geophysical logs (caliper, acoustic televiewer, natural gamma, single-point resistance, vertical flow, and fluid temperature and resistivity) and borehole video logs in the seven wells were evaluated to assess potential for lithologic correlation and to identify and describe water-bearing features, which included both low- and high-angle fractures and other openings oriented along dipping bedding planes, joints, or possible faults. Borehole geophysical logs collected by USGS in 1992 in a 300-ft-deep former production well near the Site were also evaluated. Few to no distinctive features were identified on geophysical logs (natural gamma and single-point resistance) that could be used for correlation, thus limiting this approach to determining local geologic structure. Extensive fracturing in the upper 62 ft of monitoring well MG 2220 indicates that the well was likely drilled through a zone of faulting, and other evidence of faulting is present in the area near the Site. Assessment of continuous water levels showed hydraulic connections among some wells as indicated by rising or falling water levels in response to changes in pumping rates at nearby wells. A map of water levels measured in April 2018 indicates potential for groundwater flow generally toward the stream to the south and southwest of the Site, but the limited water-level data are insufficient to describe vertical groundwater gradients or lateral gradients in any detail. Review of 1999–2022 volatile organic compound (VOC) monitoring data collected by the Pennsylvania Department of Environmental Protection for five monitoring wells indicates that the highest groundwater concentrations of PCE and TCE were found in samples from extraction well MG 2201 (S-1) downgradient from, and nearest to, the previously identified Site contaminant source area, and these concentrations fluctuated through time. PCE concentrations were higher than TCE concentrations in samples from all five monitoring wells and were much higher than TCE concentrations in samples from extraction well MG 2201 (S-1). Temporally variable recharge is a possible factor affecting observed fluctuations in PCE concentrations in groundwater samples from well extraction MG 2201 (S-1), as indicated by a general inverse relation between PCE concentrations and water levels in a nearby long-term observation well. The PCE concentration of 1,830 micrograms per liter (μg/L) in a May 2018 water sample from monitoring well MG 2220 was more than four times the PCE concentration of 444 μg/L in a December 2017 sample from the nearby extraction well MG 2201 (S-1), which is open to fewer fractures. Low concentrations of VOCs were measured in surface water at two stream sites downgradient from wells with the highest groundwater VOC concentrations at the Site, indicating that discharge of contaminated groundwater to the stream is likely. Development of a conceptual model of the groundwater system was constrained by limited data. In areas with no pumping, groundwater-flow directions generally are thought to be controlled by topography and geologic structure (bedding orientation) and likely to the south and southwest of the Site, with local flow directions affected by orientations of fractures, joints, and local faults. Additional investigations that could help improve the conceptual model of the groundwater system and help delineate the extent of groundwater contamination and its transport are discussed.

Pennsylvania↗
USGS1984

Geochemical maps of the Cornplanter Roadless Area, Warren County, Pennsylvania

The U.S. Geological Survey (USGS) made a reconnaissance geochemical survey of the Cornplanter Roadless Area (fig. 1) to test for indistinct or unexposed mineral deposits that might be recognized by their geochemical halos or patterns formed by the distribution of trace elements. Lesure, assisted by Andrew E. Grosz, collected 22 stream-sediment, 63 soil, and 23 rock samples from within and dear the study area during October 1980. All samples were analyzed for 31 elements using semi-quantitative spectrographic methods by Day in USGS laboratories, Denver, Colo. (table 1). In addition, the samples were also analyzed for zinc by means of an atomic absorption method by B.F. Arbogast and W.C. Martin, USGS laboratories, Denver Colo. J.T. Hanley and P.G. Schruben formatted the analytical data by computer methods for table 1.

Pennsylvania↗