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Research about Williams River

Source-linked reports with geographic coverage including Williams River.

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USGS1997

Level II scour analysis for Bridge 43 (CHESVT00110043) on State Highway 11, crossing the Middle Branch Williams River, Chester, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure CHESVT00110043 on State Route 11 crossing the Middle Branch of 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 principally in the Green Mountain section of the New England physiographic province in southeastern Vermont. The 13.7-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is predominantly forest except for the area downstream and right of the bridge which is pasture. In the study area, the Middle Branch of the Williams River has a sinuous channel with a slope of approximately 0.01 ft/ft, an average channel top width of 77 ft and an average bank height of 8 ft. The channel bed material ranges from gravel to boulder with a median grain size (D 50 ) of 76.6 mm (0.251 ft). The geomorphic assessment at the time of the Level I and Level II site visit on September 11, 1996, indicated that the reach was laterally unstable. Lateral instability was evident from the several point bars and cut banks located through the study reach. The State Route 11 crossing of the Middle Branch of the Williams River is a 76-ft-long, two-lane bridge consisting of two 37-foot concrete Tee-beam spans (Vermont Agency of Transportation, written communication, March 29, 1995). The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 35 degrees to the opening. The computed opening-skew-to-roadway was 30 degrees but the historical records indicate this angle is 25 degrees. Scour protection measures at the site consist of type-1 stone fill (less than 12 inches diameter) along the downstream banks and the upstream right wing wall. Type-2 (less than 36 inches diameter) stone fill protection is noted on the upstream and downstream left wingwalls and upstream along the left 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 ranged from 0.0 to 1.5 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 7.2 to 10.7 ft. The worst-case abutment scour occurred at the 500-year discharge for the right abutment. Pier scour ranged from 7.3 to 8.6 ft. The worst-case pier 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 12 (CHESVT01030012) on State Highway 103, crossing the Williams River, Chester, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure CHESVT01030012 on State Route 103 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 eastern Vermont. The 23.9-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is pasture on the downstream right and upstream left overbank areas and short grass on the downstream left and upstream right overbank areas. The surface cover along the upstream and downstream immediate banks consists of trees and brush. In the study area, the the Williams River has an incised, sinuous channel with a slope of approximately 0.0054 ft/ft, an average channel top width of 75 ft and an average bank height of 4 ft. The predominant channel bed material is gravel with a median grain size (D 50 ) of 52.4 mm (0.172 ft). The geomorphic assessment at the time of the Level I and Level II site visit on September 18, 1996, indicated that the reach was laterally unstable. The State Route 103 crossing of the Williams River is a 99-ft-long, two-lane bridge consisting of three concrete T-beam spans (Vermont Agency of Transportation, written communication, March 29, 1995). The bridge is supported by two piers and vertical, concrete abutments with wingwalls and spill-through slopes. The channel is skewed approximately 20 degrees to the opening while the opening-skew-to-roadway is 0 degrees. Downstream of the bridge are the remains of a dam which is acting as a drop structure. A scour hole, approximately 3 ft deeper than the mean thalweg depth, was observed along the upstream left bank extending from 78 ft upstream of the upstream bridge face to 25 ft downstream of the downstream bridge face during the Level I assessment. Lateral migration of the channel has resulted in flow being directed at an angle to the piers, which has resulted in increased local scour at the bridge. The scour protection measures at the site included type-2 stone fill (less than 36 inches diameter) under the bridge along the entire base length of the left and right spill-through slopes and extending up to the abutments. Type-2 stone fill (less than 36 inches diameter) scour protection was also found along the upstream left bank from the bridge to 46 ft upstream and along the downstream right bank from the bridge to 70 ft downstream. Rock walls were found along the left bank from 88 ft to 200 ft downstream and along the right bank from 124 ft to 224 ft downstream. There are two wood pile drop structures located at 47 ft and 61 ft 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 0.2 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 4.0 to 12.4 ft along the right spill-through abutment and from 8.4 to 10.7 ft along the left spill- through abutment. The worst-case abutment scour occurred at the 500-year discharge. Pier scour ranged from 7.1 to 8.9 ft along Pier 1 ( northerly pier) and from 13.5 to 17.1 ft along Pier 2 (southerly pier). The worst case pier 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 63 (CHESTH00090063) on Town Highway 9, crossing the Williams River, Chester, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure CHESTH00090063 on Town Highway 9 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 eastern Vermont. The 24.0-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is grass with trees and brush along the immediate banks. In the study area, the the Williams River has an incised, sinuous channel with a slope of approximately 0.005 ft/ft, an average channel top width of 64 ft and an average bank height of 6 ft. The channel bed material ranges from gravel to boulder with a median grain size (D 50 ) of 57.7 mm (0.189 ft). The geomorphic assessment at the time of the Level I and Level II site visit on September 18, 1996, indicated that the reach was stable. The Town Highway 9 crossing of the Williams River is a 45-ft-long, two-lane bridge consisting of one 35-foot steel-beam span with a timber deck (Vermont Agency of Transportation, written communication, April 6, 1995). The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 5 degrees to the opening while the opening-skew-to-roadway is 0 degrees. A scour hole 1.8 ft deeper than the mean thalweg depth was observed along the left abutment during the Level I assessment. The scour hole undermines the left abutment and extends from 50 ft upstream of the upstream bridge face to 50 ft downstream of the downstream bridge face. The scour protection measures at the site included type-3 stone fill (less than 48 inches diameter) under the bridge along the entire base length of the right abutment and along the right bank from 50 to 88 ft upstream. Type-2 (less than 36 inches diameter) stone fill scour protection was observed along the downstream left bank from 18 ft to 115 ft, along the downstream right bank from 8 ft to 25 ft and along the upstream left bank from 50 to 75 ft. 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 computed to be 0.0 ft. Abutment scour ranged from 10.1 ft to 11.0 ft along the left abutment and from 14.1 ft to 15.1 ft along the right abutment. The worst-case abutment scour for the left abutment occurred at the 500-year discharge while the worst-case abutment scour for the right abutment occurred at 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 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 41 (ANDOVT00110041) on State Route 11, crossing the Middle Branch Williams River, Andover, Vermont

This report provides the results of a detailed Level II analysis of scour potential at structure ANDOVT00110041 on State Route 11 crossing the Middle Branch Williams River, Andover, 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 southeastern Vermont. The 12.1-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 right overbank while the immediate banks have dense woody vegetation. The upstream left overbank and downstream right overbank are brushland. The downstream left overbank is forested. In the study area, the Middle Branch Williams River has an incised, sinuous channel with a slope of approximately 0.018 ft/ft, an average channel top width of 71 ft and an average bank height of 4 ft. The channel bed material ranges from gravel to boulders with a median grain size (D 50 ) of 85.0 mm (0.279 ft). The geomorphic assessment at the time of the Level I and Level II site visit on September 10, 1996, indicated that the reach was laterally unstable due to a cut-bank present on the upstream right bank and a wide channel bar with vegetation in the upstream reach. The State Route 11 crossing of the Middle Branch Williams River is a 46-ft-long, two-lane bridge consisting of a concrete 44-foot tee-beam span (Vermont Agency of Transportation, written communication, March 29, 1995). The opening length of the structure parallel to the bridge face is 42 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 35 degrees to the opening while the opening-skew-toroadway is zero degrees. A scour hole 0.8 ft deeper than the mean thalweg depth was observed along the downstream end of the left abutment and downstream left wingwall during the Level I assessment. Type- 2 stone fill (less than 36 inches diameter) protects the upstream end of the upstream left wingwall, the downstream ends of the downstream left and right wingwalls and the downstream right road embankment. Type-3 stone fill protects the upstream end of the upstream right wingwall and the upstream 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). 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 0.0 to 2.1 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 11.1 to 18.7 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↗