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Laura Medalie

Publications and source records attributed to Laura Medalie.

At least 73 records · Page 4Linked to original sources
USGS1997

Level II scour analysis for Bridge 17 (RIPTTH00180017) on Town Highway 18, crossing the South Branch Middlebury River, Ripton, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure RIPTTH00180017 on Town Highway 18 crossing the South Branch Middlebury River, Ripton, 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 west-central Vermont. The 15.5-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 on the upstream left bank where it is shrubs and brush. In the study area, the South Branch Middlebury River has an incised, sinuous channel with a slope of approximately 0.03 ft/ft, an average channel top width of 86 ft and an average bank height of 10 ft. The channel bed material ranges from gravel to boulders with a median grain size (D 50 ) of 111 mm (0.364 ft). In addition, there is a bedrock outcrop across the channel downstream of the bridge. The geomorphic assessment at the time of the Level I and Level II site visit on June 10, 1996, indicated that the reach was stable. The Town Highway 18 crossing of the South Branch Middlebury River is a 61-ft-long, one-lane bridge consisting of one 58-foot steel-beam span (Vermont Agency of Transportation, written communication, November 30, 1995). The opening length of the structure parallel to the bridge face is 56.8 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 40 degrees to the opening while the computed opening-skew-to-roadway is 30. A scour hole 1.25 ft deeper than the mean thalweg depth was observed along the right abutment and the downstream right wingwall during the Level I assessment. The scour protection measures at the site include type-2 stone fill (less than 36 inches diameter) along the left abutment and it’s wingwalls and at the upstream end of the right abutment. Also, type-3 stone fill (less than 48 inches diameter) is along the upstream right wingwall. 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) for the 100- and 500-year discharges. In addition, the incipient roadway-overtopping discharge is determined and analyzed as another potential worst-case scour scenario. 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 0.1 to 1.1 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 5.6 to 9.0 ft. 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”. 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 particle-size 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 21 (MORETH00010021) on Town Highway 1, crossing Cox Brook, Moretown, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure MORETH00010021 on Town Highway 1 crossing Cox Brook, Moretown, 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 2.85-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is predominantly forested. In the study area, Cox Brook has an incised, sinuous channel with a slope of approximately 0.02 ft/ft, an average channel top width of 23 ft and an average bank height of 4 ft. The channel bed material ranges from gravel to cobble with a median grain size (D 50 ) of 47.5 mm (0.156 ft). The geomorphic assessment at the time of the Level I and Level II site visit on July 18, 1996, indicated that the reach was stable. The Town Highway 1 crossing of Cox Brook is a 29-ft-long, two-lane bridge consisting of one 27-foot steel-beam span (Vermont Agency of Transportation, written communication, October 13, 1995). The opening length of the structure parallel to the bridge face is 24.8 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 60 degrees to the opening while the measured opening-skew-to-roadway is 40 degrees. A scour hole 1.0 ft deeper than the mean thalweg depth was observed along the left abutment downstream during the Level I assessment. The only scour protection measure at the site was type-2 stone fill (less than 36 inches diameter) along the left bank upstream. 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) for the 100-year and 500-year discharges. In addition, the incipient roadway-overtopping discharge is determined and analyzed as another potential worst-case scour scenario. 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 0.2 to 0.5 ft. The worst-case contraction scour occurred at the incipient roadway-overtopping discharge, which was less than the 100-year discharge. Abutment scour ranged from 2.8 to 4.0 ft. The worst-case abutment scour occurred at the left abutment at the 100-year discharge and at the right abutment at the 500-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 particle-size 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 21 (MONKTH00340021) on Town Highway 34, crossing Little Otter Creek, Monkton, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure MONKTH00340021 on Town Highway 34 crossing Little Otter Creek, Monkton, 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 D 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 C. The site is in the Champlain section of the Saint Lawrence Valley physiographic province in northwestern Vermont. The 34.1-mi 2 drainage area is in a predominantly rural and forested basin with pasture in the valleys. In the vicinity of the study site, the surface cover consists of pasture. The most significant tree cover is immediately adjacent to the channel on the right bank downstream. In the study area, Little Otter Creek has a sinuous channel with a slope of approximately 0.008 ft/ft, an average channel top width of 92 feet and an average bank height of 6 feet. The predominant channel bed materials are silt and clay. Sieve analysis indicates that greater than 50% of the sample is silt and clay and thus a median grain size by use of sieve analysis was indeterminate. Therefore, the median grain size was assumed to be medium silt with a size (D 50 ) of 0.0310 mm (0.000102 ft). The geomorphic assessment at the time of the Level I and Level II site visit on June 19 and June 20, 1996, indicated that the reach was stable. The Town Highway 34 crossing of Little Otter Creek is a 50-ft-long, one-lane bridge consisting of one 26-foot concrete span and three “boiler tube” smooth metal pipe culverts through the left road approach (Vermont Agency of Transportation, written communication, December 15, 1995). The opening length of the bridge parallel to the bridge face is 25.1 feet. The bridge is supported by vertical, concrete abutments with wingwalls on the right abutment only. The channel is skewed approximately 25 degrees to the opening. The VTAOT records indicate the opening-skew-to-roadway is 20 degrees but measurement from surveyed data suggests the skew is five degrees. The scour protection measures at the site were type-1 stone fill (less than 12 inches diameter) on the upstream and downstream embankments of the left road approach and type-2 stone fill (less than 36 inches diameter) surrounding the entrance of each culvert. Additional details describing conditions at the site are included in the Level II Summary and Appendices C and D. Scour depths and recommended rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995) for the 100- and 500-year discharges. In addition, the incipient roadway-overtopping discharge is determined and analyzed as another potential worst-case scour scenario. 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 10.3 to 12.3 feet. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 8.6 to 22.5 feet. The worst-case abutment scour occurred at the 500-year discharge for the left abutment and at the incipient overtopping discharge for the right abutment. 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 particle-size 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 17 (LYNDTH00020017) on Town Highway 2, crossing Hawkins Brook, Lyndon, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure LYNDTH00020017 on Town Highway 2 crossing Hawkins Brook, Lyndon, 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 northeastern Vermont. The 7.7-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is forest on the left and right upstream overbanks. The downstream left and right overbanks are brushland. In the study area, Hawkins Brook has an incised, sinuous channel with a slope of approximately 0.02 ft/ft, an average channel top width of 78 ft and an average bank height of 7.3 ft. The channel bed material ranges from sand to boulder with a median grain size (D 50 ) of 46.6 mm (0.153 ft). The geomorphic assessment at the time of the Level I and Level II site visit on August 4, 1995, indicated that the reach was laterally unstable with the presence of point bars and side bars. The Town Highway 2 crossing of Hawkins Brook is a 49-ft-long, two-lane bridge consisting of a 46-foot steel-stringer span (Vermont Agency of Transportation, written communication, March 27, 1995). The opening length of the structure parallel to the bridge face is 43 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 45 degrees to the opening while the computed opening-skew-to-roadway is zero degrees. A scour hole 0.75 ft deeper than the mean thalweg depth was observed along the downstream left abutment during the Level I assessment. The only scour protection measure at the site was type-2 stone fill (less than 36 inches diameter) at the upstream end of the downstream left wingwall. 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) for the 100- and 500-year discharges. 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 0.1 to 0.9 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 3.8 to 6.6 ft. 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”. 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 particle-size 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 4 (MAIDTH00070004) on Town Highway 7, crossing Cutler Mill Brook, Maidstone, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure MAIDTH00070004 on Town Highway 7 crossing the Cutler Mill Brook, Maidstone, 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 White Mountain section of the New England physiographic province in northeastern Vermont. The 18.1-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is predominantly shrub and brushland. In the study area, the Cutler Mill Brook has a non-incised, meandering channel with local braiding and a slope of approximately 0.004 ft/ft, an average channel top width of 43 ft and an average bank height of 2 ft. The channel bed material ranges from sand to cobble with a median grain size (D 50 ) of 27.6 mm (0.091 ft). The geomorphic assessment at the time of the Level I and Level II site visit on July 19, 1995, indicated that the reach was laterally unstable due to large meanders in the channel. The Town Highway 7 crossing of the Cutler Mill Brook is a 25-ft-long, one-lane bridge consisting of one 22-foot concrete span (Vermont Agency of Transportation, written communication, August 5, 1994). The opening length of the structure parallel to the bridge face is 21.7 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 20 degrees to the opening while the opening-skew-to-roadway is 0 degrees. A scour hole 2.0 ft deeper than the mean thalweg depth was observed along the left abutment during the Level I assessment. The only scour protection measure at the site was type-2 stone fill (less than 36 inches diameter) along both banks upstream, along the entire base length of the upstream left wingwall, and along the upstream end of the upstream right wingwall. 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) for the 100- and 500-year discharges. In addition, the incipient roadway-overtopping discharge was determined and analyzed as another potential worst-case scour scenario. 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 2.2 to 4.2 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 5.7 to 12.4 ft. 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”. 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 particle-size 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 53 (CHESTH01180053) on Town Highway 118, crossing the Williams River, Chester, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure CHESTH01180053 on Town Highway 118 crossing the Williams River, Chester, 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 southeastern Vermont. The 20.8-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is predominantly suburban while the right bank upstream is pasture. There is a house on the right bank downstream and VT 103 runs parallel to the river along the left bank. In the study area, the Williams River has an incised, straight channel with a slope of approximately 0.005 ft/ft, an average channel top width of 64 ft and an average bank height of 7 ft. The channel bed material ranges from sand to boulder with a median grain size (D 50 ) of 58.0 mm (0.190 ft). The geomorphic assessment at the time of the Level I and Level II site visit on September 17, 1996, indicated that the reach was stable. The Town Highway 118 crossing of the Williams River is a 43-ft-long, one-lane bridge consisting of one 40-foot steel-beam span (Vermont Agency of Transportation, written communication, April 6, 1995). The opening length of the structure parallel to the bridge face is 37.6 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 5 degrees to the opening while the computed opening-skew-to-roadway is 10 degrees. A scour hole 0.5 ft deeper than the mean thalweg depth was observed at both abutments during the Level I assessment. Scour protection measures at the site include: type-3 stone fill (less than 48 inches diameter) along the left bank upstream and downstream and type-2 stone fill (less than 36 inches diameter) along the entire base length of the upstream left wingwall, at the upstream end of the left abutment, and at the upstream end of the downstream left wingwall. 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) for the 100- and 500-year discharges. In addition, the incipient roadway-overtopping discharge is determined and analyzed as another potential worst-case scour scenario. 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 5.8 to 6.8 ft at the left abutment and 9.4 to 14.4 ft at the right abutment. The worst-case abutment scour occurred at the incipient roadway-overtopping 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 particle-size 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 37 (CABOTH00410037) on Town Highway 41, crossing the Winooski River, Cabot, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure CABOTH00410037 on Town Highway 41 crossing the Winooski River (also referred to as Coit’s Pond Brook), Cabot, 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 northeastern Vermont. The 21.4-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is primarily shrub and brushland while the immediate banks have dense woody vegetation. In the study area, the Winooski River has an incised, straight channel with a slope of approximately 0.01 ft/ft, an average channel top width of 53 ft and an average bank height of 4 ft. The channel bed material is primarily cobbles and boulder with a median grain size (D 50 ) of 64.5 mm (0.212 ft). The geomorphic assessment at the time of the Level I and Level II site visit on July 16, 1996, indicated that the reach was stable. The Town Highway 41 crossing of the Winooski River is a 29-ft-long, one-lane bridge consisting of one 26-foot span (Vermont Agency of Transportation, written communication, October 13, 1995) with four steel I-beams and a wooden deck . The opening length of the structure parallel to the bridge face is 26 ft.The bridge is supported by “laid up” granite block abutments with concrete footings. The channel is skewed approximately 35 degrees to the opening while the computed opening-skew-to-roadway is 15 degrees. The VTAOT computed opening-skew-to-roadway is zero degrees. The only scour protection measure observed at the site during the Level I assessment was type-2 stone fill (less than 36 inches diameter) along the entire base length of the left abutment and upstream right wingwall, along the upstream left bank and along the downstream left and right banks. 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) for the 100- and 500-year discharges. In addition, the incipient roadway-overtopping and maximum free-surface flow discharges were determined and analyzed as two other potential worst-case scour scenarios. 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 2.7 ft. The worst-case contraction scour occurred at the maximum free-surface flow (with road overflow) discharge, which was less than the 100-year discharge. Abutment scour ranged from 9.8 to 10.7 ft along the left abutment and from 16.2 to 19.9 ft along the right abutment. The worstcase 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 and Hire equations (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 21 (WALDTH00450021) on Town Highway 45, crossing Joes Brook, Walden, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure WALDTH00450021 on Town Highway 45 crossing Joes Brook, Walden, 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 VTAOT files state that the stream is Coles Brook, both the USGS and the VTAOT maps state that it is Joes Brook. The site is in the New England Upland section of the New England physiographic province in central Vermont. The 18.7-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is pasture upstream and downstream of the bridge while the immediate banks have dense woody vegetation. In the study area, Joes Brook has an incised, sinuous channel with a slope of approximately 0.01 ft/ft, an average channel top width of 76 ft and an average bank height of 5 ft. The channel bed material ranges from sand to boulder with a median grain size (D 50 ) of 75.4 mm (0.247 ft). The geomorphic assessment at the time of the Level I and Level II site visit on July 27, 1995, indicated that the reach was stable. The Town Highway 45 crossing of Joes Brook is a 35-ft-long, one-lane bridge consisting of one 29-foot steel-beam span with a wooden deck (Vermont Agency of Transportation, written communication, April 5, 1995). The opening length of the structure parallel to the bridge face is 26.2 ft. The bridge is supported by vertical, “laid-up” concrete block abutments with no wingwalls. The channel is skewed approximately zero degrees to the opening while the computed opening-skew-to-roadway is 5 degrees. The scour protection measures at the site included type-1 stone fill (less than 12 inches diameter) along the upstream left bank and along the entire base length of the left abutment. There is also type-2 stone fill (less than 36 inches diameter) along the entire base length of the right abutment. 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) for the 100- and 500-year discharges. In addition, the incipient roadway-overtopping discharge is determined and analyzed as another potential worst-case scour scenario. 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 1.5 ft. The worst-case contraction scour occurred at the incipient roadway-overtopping discharge, which was less than the 100-year discharge. Abutment scour ranged from 12.4 to 24.4 ft. 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 19 (SHEFTH00440019) on Town Highway 44, crossing Trout Brook, Sheffield, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure SHEFTH00440019 on Town Highway 44 crossing Trout Brook, Sheffield, 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 White Mountain section of the New England physiographic province in northeastern Vermont. The 3.0-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is grass on the upstream and downstream right overbanks, while the immediate banks have dense woody vegetation. The surface cover of the upstream and downstream left overbanks is shrub and brushland. In the study area, Trout Brook has an incised, sinuous channel with a slope of approximately 0.03 ft/ft, an average channel top width of 45 ft and an average bank height of 6 ft. The channel bed material ranges from sand to boulder with a median grain size (D 50 ) of 116 mm (0.381 ft). The geomorphic assessment at the time of the Level I and Level II site visit on July 31, 1995, indicated that the reach was stable. The Town Highway 44 crossing of Trout Brook is a 24-ft-long, one-lane bridge consisting of a 22-foot steel-stringer span (Vermont Agency of Transportation, written communication, March 28, 1994). The opening length of the structure parallel to the bridge face is 19.8 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-to-roadway is zero degrees. Scour depths and recommended rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995) for the 100- and 500-year discharges. In addition, the incipient roadway-overtopping discharge was analyzed since it has the potential of being the worst-case scour scenario. 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 resulted in zero ft. Left abutment scour ranged from 4.4 to 5.6 ft. The worst-case left abutment scour occurred at the 500-year discharge. Right abutment scour ranged from 3.6 to 4.8 ft. The worst-case right abutment scour occurred at the incipient roadway-overtopping 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↗
USGS1996

Level II scour analysis for Bridge 1 (BLOOTH00020001) on Town Highway 2, crossing Mill Brook, Bloomfield, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure BLOOTH00020001 on town highway 2 crossing Mill Brook, Bloomfield, 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 White Mountain section of the New England Upland physiographic province of north-east Vermont in the town of Bloomfield. The 4.85-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the banks have dense woody vegetation coverage. In the study area, Mill Brook has an incised, sinuous channel with a slope of approximately 0.03 ft/ft, an average channel top width of 28 ft and an average channel depth of 4 ft. The predominant channel bed materials are gravel and cobbles (D 50 is 57.3 mm or 0.188 ft). The geomorphic assessment at the time of the Level I and Level II site visit on July 6, 1995, indicated that the reach was stable. The town highway 2 crossing of Mill Brook is a 26-ft-long, one-lane bridge consisting of one 24-foot concrete span (Vermont Agency of Transportation, written commun., August 4, 1994). The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 30 degrees to the opening while the opening-skew-to-roadway is 10 degrees. No scour was observed along the channel or at the bridge during the Level I assessment. Type-2 stone fill (less than 24 inches diameter) was noted as present along all wingwalls. 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 aggradation or degradation; 2) contraction scour (due to reduction in flow area caused by 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 scour depths for contraction and local scour and a summary of the results follows. Contraction scour for all modelled flows ranged from 0 to 1.0 feet and the worst-case contraction scour occurred at the incipient overtopping discharge. Abutment scour ranged from 7.3 to 10.1 feet and 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”. 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 particle-size 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 46 (ENOSVT01080046) on State Route 108, crossing an Unnamed "The Branch" Tributary, Enosburg, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure ENOSVT01080046 on State Route 108 crossing an unnamed "The Branch" tributary, Enosburg, 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 1.55-mi 2 drainage area is in a predominantly rural, pasture and forested basin. In the vicinity of the study site, the surface cover is pasture. In the study area, this unnamed "The Branch" tributary has an incised, sinuous channel with a slope of approximately 0.03 ft/ft, an average channel top width of 45 ft and an average channel depth of 3 ft. The predominant channel bed material is gravel and cobbles with a median grain size (D 50 ) of 42.4 mm (0.139 ft). The geomorphic assessment at the time of the Level I and Level II site visit on June 29, 1995, indicated that the reach was laterally unstable. Block failure slumping of bank material was evident at an upstream cut-bank and another minor cut-bank was noted downstream. The State Route 108 crossing of this unnamed "The Branch" tributary is a 25-ft-long, twolane bridge consisting of one 22-foot concrete span (Vermont Agency of Transportation, written communication, March 8, 1995). The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 10 degrees to the opening while the opening-skew-to-roadway is zero degrees. The only scour protection measure at the site was type-2 stone fill (less than 36 inches diameter) at the downstream end of the downstream left wingwall. 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 0.3 to 0.5 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 4.0 to 8.0 ft. 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”. 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 particle-size 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↗
USGS1995

Estimated withdrawals and use of freshwater in Vermont, 1990

Estimated freshwater withdrawals during 1990 in Vermont totaled about 632 million gallons per day. The largest withdrawals were for thermoelectric- power generation (82 percent), industrial use (7 percent), and public supply (6 percent). Most withdrawals, 587 million gallons per day, were made from surface-water sources as compared to 44.9 million gallons per day from ground-water sources. The largest withdrawals were in the Upper Connecticut-Mascomo River Basin (525 million gallons per day). About 17,700 million gallons per day were used instream for hydroelectric-poser generation, the largest of which were in the Upper Connecticut-Mascoma and Otter River Basins. Other information describing water-use patters is shown in tables, bar graphs, pie charts, maps, and accompanying text. The data are aggregated by river basin (hydrologic cataloging unit), and all amounts are reports in million gallons per day.

Vermont↗
USGS1995

Geohydrology and water quality of stratified-drift aquifers in the Saco and Ossipee River basins, east-central New Hampshire

Stratified-drift aquifers discontinuously underlie 152.5 square miles of the Saco and Ossipee River Basins, which have a total drainage area of 869.4 square miles. Saturated thicknesses of stratified drift in the study area are locally greater than 280 feet, but generally are less. Transmissivity locally exceeds 8,000 feet squared per day but are generally less. About 93.6 square miles, or 10.8 percent of the study area, are identified as having transmissivity greater than 1,000 feet squared per day. The stratified-drift aquifer in Ossipee, Freedom, Effingham, Madison, and Tamworth was analyzed for the availability of ground water by use of transient simulations and a two-dimensional, finite-difference ground-water-flow model. The numerical -model results indicate that potential available water amounts in this aquifer are 7.72 million gallons per day. Sample results of water- quality analyses obtained from 25 test wells and 4 springs indicated that water was generally suitable for drinking and other domestic purposes. Concen- trations of dissolved constituents in ground-water samples are less than or meet U.S. Environmental Protection Agency (USEPA)primary and secondary drinking-water regulations. Concentrations of inorganic constituents that exceeded the USEPA's secondary regulations were chloride and sodium, iron manganese, and fluoride.

Water-Resources Investigations Report↗