USGS Science⌕ Search

SEARCH · USGS Science

Results for “Materials Performance”

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 235 records · Page 13Linked to original sources
USGS2003

Questa baseline and pre-mining ground water investigation: 11. Geochemistry of composited material from alteration scars and mine-waste piles

Composited, surficial material was collected from alteration scars, a less intensely altered site, and mine-waste piles. All samples were analyzed for forty elements by inductively coupled plasma-atomic emission spectrometry, total sulfur and quantitative X-ray diffraction. This work was performed in cooperation with the New Mexico Environment Department.

New Mexico↗
USGS2004

Engineering geologic conditions at the sinkhole entrance to Logan Cave, Benton County, Arkansas

Logan Cave, located in Benton County, Arkansas, is inhabited by several endangered and threatened species. The cave and surrounding area was designated a National Wildlife Refuge under the control of the U.S. Fish and Wildlife Service (USFWS) in 1989. Cave researchers access the cave through a steep-sided sinkhole entrance, which also is one of the two access points used by endangered bats. There is evidence of instability of one of the entrance slopes that has raised concerns that the entrance could close if slope failure was to occur. At the request of USFWS, we performed an engineering geologic investigation of the sinkhole to evaluate stability of this slope, which is comprised of soil, and other mechanisms of sediment transport into the cave entrance. The investigation included engineering geologic mapping, sampling and laboratory testing of subsurface geologic materials, and slope-stability analysis. We found that the sinkhole slope that extends into the entrance of the cave is comprised of sandy and gravelly soil to the depths explored (6.4 meters). This soil likely was deposited as alluvium within a previous, larger sinkhole. Based on properties of the alluvium, geometry of the slope, and results of finite-element slope-stability analyses, we conclude that the slope is marginally stable. Future failures of the slope probably would be relatively thin and small, thus several would be required to completely close the cave entrance. However, sediment is accumulating within the cave entrance due to foot traffic of those accessing the cave, surface-water erosion and transport, and shallow slope failures from the other sinkhole slopes. We conclude that the entrance will be closed by sediment in the future, similar to another entrance that we identified that completely closed in the past. Several measures could be taken to reduce the potential for closure of the cave entrance, including periodic sediment removal, installation of materials that reduce erosion by foot traffic and surface water, construction of a sediment-retention wall, and excavation of the soil slope. Any measures taken must be carefully planned and executed so that they have no impact on organisms within the cave.

Open-File Report↗
USGS2018

Effects of transmitter type, tagging method, body size, and temperature on behavior, physiology, and swimming performance of juvenile Chinook salmon (Oncorhynchus tshawytscha)

The objective of this study was to assess the impact of different tagging methods and transmitter types on juvenile salmonid behavior, mortality, physiology, and swimming performance over a range of water temperatures and fish sizes. In Chapter 1, two laboratory experiments were conducted to assess maximum burst-swimming speeds, the probability of gulping air, swimming angles, and the probability of resting on a screen in a swim tunnel. For the burst swim speed experiment, we identified a slightly reduced, but statistically significant difference in burst-swimming speeds for gastric- and surgical-tagged fish implanted with dummy radio and acoustic transmitters. For the swim tunnel experiment, surgical-tagged fish were one-half as likely to gulp air at the surface of the swim tunnel as untagged and gastric-tagged fish. We observed higher probabilities of fish gulping air at the surface for fish with tag ratios greater than 5 percent, suggesting that smaller fish required greater adjustment to their buoyancy than larger fish. We also observed that gastric-tagged fish had, on average, steeper swimming angles than untagged and surgical-tagged fish in the swim tunnel. In Chapter 2, we conducted a field-based laboratory experiment at John Day Dam to assess the sustained swimming performance (i.e., critical swimming speed or U crit ) of in-river migrating subyearling Chinook salmon that were surgically implanted with dummy radio and acoustic transmitters. Statistical tests indicated a significant reduction (about 8.3 centimeters per second [cm/s] or 1 body length per second) in sustained swimming performance for fish implanted with either radio or acoustic transmitters. We also found a significant reduction in U crit of -1.38 cm/s for every 1 degree Celsius (°C) increase in temperature. In Chapter 3, we assessed the effects of water temperature on the physiology, mortality, and swimming performance of juvenile Chinook salmon in laboratory and field experiments. Juvenile Chinook salmon generally showed elevated stress response, elevated mortality, and reduced swimming performance as water temperature increased. We concluded that the water temperature threshold for handling and tagging fish with minimal impacts seems to be near 23 °C. At 25 °C, we documented very high mortality and dramatically reduced swimming performance of tagged fish relative to controls. Telemetry studies conducted at 25 °C would not meet the critical assumption that the transmitter has minimal impacts on the study fish. In the Chapter 4, we evaluated the effects of antenna length and antenna material on the subsequent tag output power, reception, and detection of tagged fish. In a laboratory, we compared the relative signal strengths in water of 150-megahertz transmitters over a range of antenna lengths (from 6 to 30 cm) and materials (one weighing about one-half of the other). The peak relative signal strengths were at 20 and 22 cm, which are about 1 wavelength underwater at the test frequency. The peak relative signal strengths at these antenna lengths were about 50 percent greater than those of 30-cm antennas, a length commonly used in fisheries research.

Open-File Report↗
USGS2023

Rare earth element sources, end-use demand trends, and hydrometallurgical separations

Rare earth elements are increasing in demand due to the movement towards electrification. In particular, there is a growing need for high performance rare earth permanent magnets for motors and generators used to convert electrical energy to mechanical energy, and vice versa. Current trends in rare earth demand are reviewed and discussed as the specific rare earth metal demand can influence the choice of feed material and process selection. Australia has the potential to increase the supply of these metals. Rare earth sources in Australia are briefly reviewed, with some discussion on the Mary Kathleen Uranium Tailings opportunity. Much of the cost of recovering rare earths is in the challenging chemical separations, some examples are provided using equilibrium chemical thermodynamic diagrams to explain the specific leaching and precipitation reactions.

Conference Paper↗
USGS1973

Value and validity of earth resources observations from space

Observations of the earth from space can provide overall repetitive views in various regions of the electromagnetic spectrum. Data from such surveys can be used as the basis for more detailed observations from aircraft and on the ground to guide resource exploration, development, and conservation activities. The value of earth resource observations from space has been demonstrated by the practical use of photographs from the Gemini and Apollo spaceflights and particularly by a series of multispectral photographs taken during the flight of Apollo 9. The analysis of those photographs has shown that the performance of the planned Earth Resources Technology Satellite will meet the needs of the resource and environmental community for small-scale repetitive images of the earth in the visible and solar infrared portions of the spectrum and has provided a limited base of material for earth scientists to work with in order to ready themselves for the ERTS data. The validity of earth resource observations from space can be derived by analogy from the successively closer observations of the moon, culminating in repeated physical sampling of the moon's surface. The method of inductive reasoning and analysis used for the moon is the opposite of the normal deductive analysis used on the earth. Adoption of the inductive methods and reasoning for earth observations will provide a framework of broad observations and conclusions leading to the identification of target areas for more detailed observation and will, in time, reduce the costs and time required for surveys dealing with resource and environmental problems.

Hydrological Sciences Bulletin↗
USGS1984

REMOTE-SENSING MINERAL DISCOVERIES IN THE MOJAVE DESERT OF CALIFORNIA.

As a result of remote sensing studies in the Mojave Desert of California three previously unknown stockwork molybdenum systems have been discovered. It is not known if economic deposits of molybdenum and associated minerals occur in these areas; there is, however, sufficient data to judge that these areas are worthy of further exploration. The purpose of this paper is to present case histories of two of these discoveries. These discoveries have been made from laboratory analyses of Landsat multispectral scanner images to map limonitic materials and from field reconnaissance to determine if the limonite is due to hydrothermal alteration. In those areas that seemed most promising, airborne spectrometer surveys were employed to mapped Al-OH minerals, and audio-magnetotelluric (AMT) and telluric-traversing surveys were performed to obtain information at depth.

Conference Paper↗
USGS2022

Data-driven prospectivity modelling of sediment-hosted Zn-Pb mineral systems and their critical raw materials

Demand for critical raw materials is expected to accelerate over the next few decades due to continued population growth and the shifting consumption patterns of the global economy. Sedimentary basins are important sources for critical raw materials and new discoveries of sediment–hosted Mississippi Valley–type (MVT) and/or clastic–dominated (CD) Zn–Pb deposits are likely required to mitigate future supply chain disruptions for Zn, Pb, Ag, Cd, Ga, Ge, Sb, and In. Herein we integrate public geoscience datasets using a discrete global grid to system to model the mineral potential for MVT and CD deposits across Canada, the United States of America, and Australia. Statistical analysis of the model results demonstrates that surface–wave tomography and derivative products from satellite gravity datasets can be used to map the most favourable paleo–tectonic settings of MVT and CD deposits inboard of orogenic belts and at the rifted edges of cratonic lithosphere, respectively. Basin development at pre–existing crustal boundaries was likely important for maintaining the low geothermal–gradients that are favourable for metal transport and generating the crustal fluid pathways that were reactivated during ore–formation, as suggested by the statistical association of both sediment–hosted mineral deposit types with the edges of upward–continued gravity and long–wavelength magnetic anomalies. Multivariate statistical analysis demonstrates that the most prospective combination of these geophysical datasets varies for each geological region and deposit type. We further demonstrate that maximum and minimum geological ages, coupled with Phanerozoic paleogeographic reconstructions, represent mappable proxies for the availability of oxidized, brine–generating regions that are the most likely source of ore–forming fluids (e.g., low– to mid–latitude carbonate platforms and evaporites). Ore deposition was likely controlled by interaction between oxidized, low–temperature brines and sulfidic and/or carbonaceous rocks, which, in some cases, can be mapped at the exposed surface or identified using the available rock descriptions. Baseline weights–of–evidence models are based on regional geophysics and are the least impacted by missing surface information but yield relatively poor results, as demonstrated by the low area–under–the–curve (AUC) for the spatially independent test set on the success–rate plot (AUC = 0.787 for MVT and AUC = 0.870 for CD). Model performance can be improved by: (1) using advanced methods that were trained and validated during a series of semi–automated machine learning competitions; and/or (2) incorporating geological and geophysical datasets that are proxies for each component of the mineral system. The best–performing gradient boosting machine models yield higher AUC for the test set (AUC = 0.983 for MVT and AUC = 0.991 for CD) and reduce the search space by >94%. The model results highlight the potential benefits of mapping sediment–hosted mineral systems at continental scale to improve mineral exploration targeting for critical raw materials.

Ore Geology Reviews↗
USGS2021

Small atoll fresh groundwater lenses respond to a combination of natural climatic cycles and human modified geology

Freshwater lenses underlying small ocean islands exhibit spatial variability and temporal fluctuations in volume, influencing ecologic management. For example, The Palmyra Atoll National Wildlife Refuge harbors one of the few surviving native stands of Pisonia grandis in the central Pacific Ocean, yet these trees face pressure from groundwater salinization, with little basic groundwater data to guide decision making. Adding to natural complexity, the geology of Palmyra was heavily altered by dredge and fill activities. Our study based at this atoll combines geophysical and hydrological field measurements from 2008 to 2019 with groundwater modeling to study the drivers of observed freshwater lens dynamics. Electromagnetic induction (EMI) field data were collected on the main atoll islands over repeat transects in 2008 following ‘strong’ La Niña conditions (wet) and in 2016 during ‘very strong’ El Niño conditions (dry). Shallow monitoring wells were installed adjacent to the geophysical transects in 2013 and screened within the fresh/saline groundwater transition zone. Temporal EMI and monitoring well data showed a strong contraction of the freshwater lens in response to El Niño conditions, and indicated a thicker lens toward the ocean side, an opposite spatial pattern to that observed for many other Pacific islands. On an outer islet where a stand of mature Pisonia trees exist, EMI surveys revealed only a thin (<3 m from land surface) layer of brackish groundwater during El Niño. Numerical groundwater simulations were performed for a range of permeability distributions and climate conditions at Palmyra. Results revealed that the observed atypical lens asymmetry is likely due to more efficient submarine groundwater discharge on the lagoon side as a result of lagoon dredging and filling with high-permeability material. Simulations also predict large decreases (40%) in freshwater lens volume during dry cycles and highlight threats to the Pisonia trees, yielding insight for atoll ecosystem management worldwide.

Science of the Total Environment↗
USGS2017

The fascinating and complex dynamics of geyser eruptions

Geysers episodically erupt liquid and vapor. Despite two centuries of scientific study, basic questions persist—why do geysers exist? What determines eruption intervals, durations, and heights? What initiates eruptions? Through monitoring eruption intervals, analyzing geophysical data, taking measurements within geyser conduits, performing numerical simulations, and constructing laboratory models, some of these questions have been addressed. Geysers are uncommon because they require a combination of abundant water recharge, magmatism, and rhyolite flows to supply heat and silica, and large fractures and cavities overlain by low-permeability materials to trap rising multiphase and multicomponent fluids. Eruptions are driven by the conversion of thermal to kinetic energy during decompression. Larger and deeper cavities permit larger eruptions and promote regularity by isolating water from weather variations. The ejection velocity may be limited by the speed of sound of the liquid + vapor mixture.

Annual Review of Earth and Planetary Sciences↗
USGS2005

Cold compaction of water ice

Hydrostatic compaction of granulated water ice was measured in laboratory experiments at temperatures 77 K to 120 K. We performed step-wise hydrostatic pressurization tests on 5 samples to maximum pressures P of 150 MPa, using relatively tight (0.18-0.25 mm) and broad (0.25-2.0 mm) starting grain-size distributions. Compaction change of volume is highly nonlinear in P, typical for brittle, granular materials. No time-dependent creep occurred on the lab time scale. Significant residual porosity (???0.10) remains even at highest P. Examination by scanning electron microscopy (SEM) reveals a random configuration of fractures and broad distribution of grain sizes, again consistent with brittle behavior. Residual porosity appears as smaller, well-supported micropores between ice fragments. Over the interior pressures found in smaller midsize icy satellites and Kuiper Belt objects (KBOs), substantial porosity can be sustained over solar system history in the absence of significant heating and resultant sintering. Copyright 2005 by the American Geophysical Union.

Geophysical Research Letters↗
USGS2025

Investigating hurricane-induced salt variation across the Land-Estuary-Ocean continuum using a dynamically coupled hydrological-ocean model

Salinity variations across the Land‐Estuary‐Ocean (LEO) continuum are critical for coastal ecosystems and impact the socioeconomic benefits to local communities. However, evaluating these variations is challenging due to the complex interactions of terrestrial and oceanic processes, including river discharge, winds, tides, sea level rise, and storms. This study incorporates a salinity module into a newly developed dynamically coupled hydrological‐ocean model on the COAWST platform, which is, to the best of our knowledge, the first process‐based modeling that achieves seamless two‐way land‐ocean water and salt exchanges across the LEO continuum, facilitating simulations of landward salt input and transport. Using Hurricane Florence (2018) as a case study, we examined how various physical processes influence salinity dynamics and freshwater plume development in the Cape Fear River Estuary, North Carolina. The model simulated saltwater intrusion into freshwater wetlands upstream of the estuary and demonstrated that salinity in the estuary was initially regulated by wind‐driven water level gradients, followed by a dominant influence from significant river runoff. In the coastal ocean, runoff created a large freshwater plume that moved westward, driven by the interplay between runoff, winds, and the estuary's geomorphology. The excellent performance of the coupling approach for salinity simulation underscores the importance of the seamless transport of water and salt at the land‐ocean interface. This study demonstrates that the coupled model is a valuable tool for representing saltwater intrusion, tracking coastal pollutants, and understanding water and material exchange across the LEO continuum.

North Carolina, South Carolina↗
USGS2025

Time-varying rates of organic and inorganic mass accumulation in southeast Louisiana marshes: Relationships to sea-level anomalies and tropical storms

Louisiana's coastal wetlands are complex systems that require a continuous input of organic and inorganic material to keep pace with relative sea-level rise. Coastal restoration projects such as sediment diversions are being implemented to mitigate land loss and increase availability of inorganic sediment to coastal wetlands, and marshes specifically rely on organic material to build soil volume and maintain surface elevation. Interannual-to-decadal sea-level anomalies such as hurricanes can affect marsh accretion, mineral deposition, and plant productivity. In this light, complex ecogeomorphic feedback controls whether a marsh surface is sustainable or eroded/drowns. This study performs some of the first differential vertical accretion rates (VARs) and organic and inorganic mass accumulation rates (MARs) over time in SE Louisiana marshes determined from the 210 Pb Constant Rate of Supply model, coupled with standard 137 Cs VARs. These accumulation rates over the past ∼100 years were measured from a total of six brackish and salt marsh locations in Barataria Basin near the proposed Mid-Barataria Sediment Diversion. They were then related to interannual sea-surface elevations at Grand Isle, Louisiana, over the last ∼60 years and recorded hurricane activity in the delta. Results show VARs range from 0.63 cm/y to 1.69 cm/y and total MARs range from 0.11 to 0.43 g/cm 2 /y. Temporally, VARs and MARs (total, inorganic, and organic) are characterized by gradual increases in rates with decreasing age along with episodic peaks in VARs and MARs. The findings of this study indicate that no relationship occurs between sea-level anomalies and VARs or organic and inorganic MARs; however, a strong relationship appears to occur between major hurricanes to VAR and MAR contributions. Furthermore, high water content (81 ± 8%) and organic-rich soils in the sediment cores highlight the significance of belowground biomass and associated pore volume in maintaining marsh elevation in the study area.

Louisiana↗
USGS1996

Level II scour analysis for Bridge 24 (HARDTH00490024) on Town Highway 49, crossing Nichols Brook at Mackville Pond Outlet, Hardwick, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure HARDTH00490024 on Town Highway 49 crossing Nichols Brook at Mackville Pond Outlet, Hardwick, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the New England Upland section of the New England physiographic province in north-central Vermont. The 10.7-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is best described as suburban with residences, lawns, trees and roadways. There is a dam 54 feet downstream of the bridge which controls Mackville Pond upstream of the bridge. The vertical drop over the dam is 15 feet. Immediately upstream of the bridge the width of the waterway is 146 feet. The predominant channel bed material is sand with a median grain size (D 50 ) of 0.576 mm (0.00189 ft). The geomorphic assessment at the time of the Level I and Level II site visit on July 25, 1995, indicated that the reach was stable. The Town Highway 49 crossing of Nichols Brook at Mackville Pond Outlet is a 42-ft-long, two-lane bridge consisting of one 38-foot steel-beam span (Vermont Agency of Transportation, written communication, April 3, 1995). The bridge is supported by vertical, concrete abutments with wingwalls on the downstream end of the left abutment and upstream and downstream ends of the right abutment. The channel is not skewed to the opening, but the opening-skew-to-roadway is 5 degrees. Scour protection measures at the site include type-3 stone fill (less than 48 inches diameter) on the upstream side of the left roadway embankment and at the upstream end of the left abutment. Type-2 stone fill (less than 36 inches diameter) was on the upstream right roadway embankment. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E. Scour depths and rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a highway crossing is comprised of three components: 1) long-term streambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is the sum of the three components. Equations are available to compute depths for contraction and local scour and a summary of the results of these computations follows. Contraction scour for all modelled flows ranged from 4.7 to 21.0 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour at the left abutment ranged from 13.3 to 15.8 ft. with the worst-case occurring at the 500-year discharge. Abutment scour at the right abutment ranged from 8.1 to 9.8 ft. with the worst-case occurring at the incipient roadway-overtopping discharge. Additional information on scour depths and depths to armoring are included in the section titled “Scour Results”. Scouredstreambed elevations, based on the calculated scour depths, are presented in tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure 8. Scour depths were calculated assuming an infinite depth of erosive material and a homogeneous particlesize distribution. It is generally accepted that the Froehlich equation (abutment scour) gives “excessively conservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, computed scour depths are evaluated in combination with other information including (but not limited to) historical performance during flood events, the geomorphic stability assessment, existing scour protection measures, and the results of the hydraulic analyses. Therefore, scour depths adopted by VTAOT may differ from the computed values documented herein.

Vermont↗
USGS1996

Level II scour analysis for Bridge 36 (RANDTH00480036) on Town Highway 48, crossing Snows Brook, Randolph, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure RANDTH00480036 on town highway 48 crossing Snows Brook, Randolph, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the Green Mountain section of the New England physiographic province of central Vermont. The 3.72-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is forest. In the study area, Snows Brook has an incised, sinuous channel with a slope of approximately 0.03 ft/ft, an average channel top width of 27 ft and an average channel depth of 3 ft. The predominant channel bed material is cobble with a median grain size (D50) of 72.7 mm (0.238 ft). The geomorphic assessment at the time of the Level I and Level II site visit on August 9, 1994, indicated that the reach was laterally unstable. The town highway 48 crossing of Snows Brook is a 32-ft-long, two-lane bridge consisting of one 28-foot concrete span (Vermont Agency of Transportation, written communication, July 29, 1994). The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 40 degrees to the opening while the opening-skew-toroadway is 45 degrees. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E. Scour depths and rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a highway crossing is comprised of three components: 1) long-term streambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is the sum of the three components. Equations are available to compute depths for contraction and local scour and a summary of the results of these computations follows. Contraction scour for all modelled flows ranged from 0.0 to 0.8 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 6.1 to 11.6 ft. The worst-case abutment scour occurred at the incipient-overtopping discharge, which was 50 cfs lower than the 500-year discharge. Additional information on scour depths and depths to armoring are included in the section titled “Scour Results”. Scouredstreambed elevations, based on the calculated scour depths, are presented in tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure 8. Scour depths were calculated assuming an infinite depth of erosive material and a homogeneous particlesize distribution. It is generally accepted that the Froehlich equation (abutment scour) gives “excessively conservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, computed scour depths are evaluated in combination with other information including (but not limited to) historical performance during flood events, the geomorphic stability assessment, existing scour protection measures, and the results of the hydraulic analyses. Therefore, scour depths adopted by VTAOT may differ from the computed values documented herein.

Vermont↗
USGS1997

Level II scour analysis for Bridge 49 (FFIETH00290049) on Town Highway29, crossing Black Creek, Fairfield, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure FFIETH00290049 on Town Highway 29 crossing Black Creek, Fairfield, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the Green Mountain section of the New England physiographic province in northwestern Vermont. The 83.5-mi 2 drainage area is in a predominantly rural and forested basin. There is agricultural land in the basin as well, especially along the immediate river valley. In the vicinity of the study site, the surface cover is pasture except for on the downstream right bank which has row crops. In the study area, Black Creek has an incised, meandering channel with a slope of approximately 0.0005 ft/ft, an average channel top width of 85 ft and an average bank height of 9 ft. The channel bed material ranges from sand to cobble with a median grain size (D 50 ) of 3.23 mm (0.0106 ft). The geomorphic assessment at the time of the Level I and Level II site visit on July 13, 1995, indicated that the reach was laterally unstable. This assessment was due to apparent long term lateral movement of the channel in the vicinity of the bridge. The Town Highway 29 crossing of Black Creek is a 48-ft-long, one-lane bridge consisting of one 45-foot steel pony thru-truss type span (Vermont Agency of Transportation, written communication, March 8, 1995). The opening length of the structure parallel to the bridge face is 42.5 ft.The bridge is supported by vertical, concrete abutments. The channel is skewed approximately 30 degrees to the opening while the opening-skew-to-roadway is zero degrees. Channel scour, approximately 6 ft deeper than the mean thalweg depth, was observed through the immediate channel reach including underneath the bridge. Type-2 stone fill (less than 36 inches diameter) has been placed as a scour countermeasure along both abutments, on the channel bed under the bridge and along immediate channel banks upstream and downstream of the bridge. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E. Scour depths and recommended rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a highway crossing is comprised of three components: 1) long-term streambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is the sum of the three components. Equations are available to compute depths for contraction and local scour and a summary of the results of these computations follows. Contraction scour for all modelled flows ranged from 0.0 to 4.4 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 7.5 to 14.3 ft and 12.2 to 16.3 ft on the left and right abutments respectively. The worst-case abutment scour occurred at the 500-year discharge. Additional information on scour depths and depths to armoring are included in the section titled “Scour Results”. Scouredstreambed elevations, based on the calculated scour depths, are presented in tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure 8. Scour depths were calculated assuming an infinite depth of erosive material and a homogeneous particlesize distribution. It is generally accepted that the Froehlich equation (abutment scour) gives “excessively conservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, computed scour depths are evaluated in combination with other information including (but not limited to) historical performance during flood events, the geomorphic stability assessment, existing scour protection measures, and the results of the hydraulic analyses. Therefore, scour depths adopted by VTAOT may differ from the computed values documented herein.

Vermont↗
USGS1997

Level II scour analysis for Bridge 30 (MNTGTH00410030) on Town Highway 41, crossing the Trout River, Montgomery, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure MNTGTH00410030 on Town Highway 41 crossing the Trout River, Montgomery, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the Green Mountain section of the New England physiographic province in northern Vermont. The 46.1-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover on the left bank is pasture upstream and downstream of the bridge with dense woody vegetation along the immediate banks. The upstream and downstream right bank surface cover is brush. In the study area, the Trout River has an incised, meandering channel with a slope of approximately 0.005 ft/ft, an average channel top width of 130 ft and an average bank height of 6 ft. The channel bed material ranges from sand to cobble with a median grain size (D 50 ) of 68.3 mm (0.224 ft). The geomorphic assessment at the time of the Level I and Level II site visit on June 27, 1995, indicated that the reach was laterally unstable. At this site there is visible lateral channel movement upstream and downstream of the bridge with meanders and cut banks. The Town Highway 41 crossing of the Trout River is a 90-ft-long, one-lane bridge consisting of one 87-foot steel-beam span (Vermont Agency of Transportation, written communication, August 3, 1994). The opening length of the structure parallel to the bridge face is 86.7 ft.The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 10 degrees to the opening while the opening-skew-toroadway is 0 degrees. A scour hole 4.5 ft deeper than the mean thalweg depth, was observed 35 ft downstream of the bridge during the Level I assessment. The scour counter-measures at the site included type-1 stone fill (less than 12 inches diameter) at the upstream left wingwall, at the left abutment, along the upstream right bank, and at the upstream end of the downstream left wingwall. There was also type-2 stone fill (less than 36 inches diameter) along the downstream right bank. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E. Scour depths and recommended rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a highway crossing is comprised of three components: 1) long-term streambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is the sum of the three components. Equations are available to compute depths for contraction and local scour and a summary of the results of these computations follows. Contraction scour for all modelled flows was 0.0 ft. Abutment scour ranged from 2.5 to 8.9 ft. The worst-case abutment scour occurred at the 500-year discharge. The computed scour depths are well above the pile depths set in bedrock. Additional information on scour depths and depths to armoring are included in the section titled “Scour Results”. Scouredstreambed elevations, based on the calculated scour depths, are presented in tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure 8. Scour depths were calculated assuming an infinite depth of erosive material and a homogeneous particlesize distribution. It is generally accepted that the Froehlich equation (abutment scour) gives “excessively conservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, computed scour depths are evaluated in combination with other information including (but not limited to) historical performance during flood events, the geomorphic stability assessment, existing scour protection measures, and the results of the hydraulic analyses. Therefore, scour depths adopted by VTAOT may differ from the computed values documented herein.

Vermont↗
USGS1997

Level II scour analysis for Bridge 15 (TROYTH00290015) on Town Highway 29, crossing Beetle Brook, Troy, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure TROYTH00290015 on Town Highway 29 crossing Beetle Brook, Troy, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the Green Mountain section of the New England physiographic province in north-central Vermont. The 8.97-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is forest except for the downstream right bank which is grass. In the study area, Beetle Brook has an incised, sinuous channel with a slope of approximately 0.02 ft/ft, an average channel top width of 41 ft and an average bank height of 4 ft. The channel bed material ranges from gravel to boulder with a median grain size (D 50 ) of 118 mm (0.387 ft). The geomorphic assessment at the time of the Level I and Level II site visit on June 7, 1995, indicated that the reach was stable. The Town Highway 29 crossing of Beetle Brook is a 30-ft-long, one-lane bridge consisting of one 25-foot steel-beam span (Vermont Agency of Transportation, written communication, March 7, 1994). The opening length of the structure parallel to the bridge face is 23.4 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 15 degrees to the opening while the opening-skew-toroadway is 0 degrees. A scour hole 0.5 ft deeper than the mean thalweg depth was observed along the right abutment during the Level I assessment. Scour counter measures at the site include type-3 stone fill (less than 48 inches diameter) at the downstream end of the downstream right wingwall, type-2 stone fill (less than 36 inches diameter) along the downstream left wingwall and the upstream left road embankment, and type-1 stone fill (less than 12 inches diameter) at the upstream right road embankment. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E. Scour depths and recommended rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a highway crossing is comprised of three components: 1) long-term streambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is the sum of the three components. Equations are available to compute depths for contraction and local scour and a summary of the results of these computations follows. Contraction scour for all modelled flows ranged from 0.0 to 0.6 ft. The worst-case contraction scour occurred at the incipient-overtopping discharge. Left abutment scour ranged from 8.0 to 8.9 ft. The worst-case left abutment scour occurred at the 500-year discharge. Right abutment scour ranged from 15.4 to 16.5 ft. The worst-case right abutment scour occurred at the incipient-overtopping discharge. Additional information on scour depths and depths to armoring are included in the section titled “Scour Results”. Scouredstreambed elevations, based on the calculated scour depths, are presented in tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure 8. Scour depths were calculated assuming an infinite depth of erosive material and a homogeneous particlesize distribution. It is generally accepted that the Froehlich equation (abutment scour) gives “excessively conservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, computed scour depths are evaluated in combination with other information including (but not limited to) historical performance during flood events, the geomorphic stability assessment, existing scour protection measures, and the results of the hydraulic analyses. Therefore, scour depths adopted by VTAOT may differ from the computed values documented herein.

Vermont↗
USGS1997

Level II scour analysis for Bridge 144 (ROCHVT01000144) on State Route 100, crossing the White River, Rochester, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure ROCHVT01000144 on State Route 100 crossing the White River, Rochester, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the Green Mountain section of the New England physiographic province in central Vermont. The 68.9-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is pasture with forest on the valley walls. In the study area, the White River has a meandering channel with a slope of approximately 0.003 ft/ft, an average channel top width of 119 ft and an average channel depth of 4 ft. The predominant channel bed material is gravel and cobbles with a median grain size (D 50 ) of 72.5 mm (0.238 ft). The geomorphic assessment at the time of the Level I and Level II site visit on July 22, 1996, indicated that the reach was laterally unstable due to a cut-bank present on the upstream left bank and wide point bars upstream and downstream in the vicinity of this site. The State Route 100 crossing of the White Riveris a 103-ft-long, two-lane bridge consisting of one 101-foot steel-beam span (Vermont Agency of Transportation, written communication, March 8, 1995). The bridge is supported by vertical, concrete abutment walls with spill-through embankments in front of each abutment wall and no wingwalls. The channel is skewed approximately 10 degrees to the opening while the opening-skew-toroadway is 5 degrees. The scour protection measures at the site are type-2 stone fill (less than 36 inches diameter) on the upstream left bank, both abutment spill-through embankments, and the downstream banks. There also is type-1 stone fill (less than 12 inches diameter) on the upstream right bank. The stone fill is continuous on both sides of the river in the vicinity of the bridge. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E. Scour depths and rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a highway crossing is comprised of three components: 1) long-term streambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is the sum of the three components. Equations are available to compute depths for contraction and local scour and a summary of the results of these computations follows. There was no computed contraction scour for the modelled flows. Abutment scour ranged from 6.9 to 10.9 ft. The worst-case abutment scour occurred at the incipient overtopping discharge, which was less than the 100-year discharge. Additional information on scour depths and depths to armoring are included in the section titled “Scour Results”. Scoured-streambed elevations, based on the calculated scour depths, are presented in tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure 8. Scour depths were calculated assuming an infinite depth of erosive material and a homogeneous particlesize distribution. It is generally accepted that the Froehlich equation (abutment scour) gives “excessively conservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, computed scour depths are evaluated in combination with other information including (but not limited to) historical performance during flood events, the geomorphic stability assessment, existing scour protection measures, and the results of the hydraulic analyses. Therefore, scour depths adopted by VTAOT may differ from the computed values documented herein.

Vermont↗