This report provides the results of a detailed Level II analysis of scour potential at structure \nGLOVTH00410023 on Town Highway 41 crossing Sherburne Brook, Glover, Vermont \n(figures 1–8). A Level II study is a basic engineering analysis of the site, including a \nquantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). Results of a Level I scour investigation also are included in Appendix E of this \nreport. A Level I investigation provides a qualitative geomorphic characterization of the \nstudy site. Information on the bridge, gleaned from Vermont Agency of Transportation \n(VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is \nfound in Appendix D.
\nThe site is in the New England Upland section of the New England physiographic province \nin northern Vermont. The 2.57-mi2\n drainage area is in a predominantly rural and forested \nbasin. In the vicinity of the study site, the surface cover is primarily forest with small areas \nof lawn and a home on the right overbank and a gravel roadway along the upstream left \nbank.
\nIn the study area, Sherburne Brook has an incised, sinuous channel with a slope of \napproximately 0.03 ft/ft, an average channel top width of 33 ft and an average bank height \nof 6 ft. The channel bed material ranges from gravel to boulder with a median grain size \n(D50) of 57.3 mm (0.188 ft). The geomorphic assessment at the time of the Level I and \nLevel II site visit on October 24, 1994, indicated that the reach was stable.
\nThe Town Highway 41 crossing of Sherburne Brook is a 24-ft-long, one-lane bridge \nconsisting of one 21-foot steel-beam span with a timber deck (Vermont Agency of \nTransportation, written communication, August 4, 1994). The opening length of the \nstructure parallel to the bridge face is 20.3 ft. The bridge is supported by vertical, granite \nblock abutments. The channel is skewed approximately 55 degrees to the opening while the \nmeasured opening-skew-to-roadway is 30 degrees.
\nOne foot of scour below the mean thalweg depth was observed along the right abutment \nundermining the abutment by 0.5 feet vertically. Additional details describing conditions at \nthe site are included in the Level II Summary and Appendices D and E.
\nScour depths and recommended rock rip-rap sizes were computed using the general \nguidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). \nTotal scour at a highway crossing is comprised of three components: 1) long-term \nstreambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction \nin flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and \nabutments). Total scour is the sum of the three components. Equations are available to \ncompute depths for contraction and local scour and a summary of the results of these \ncomputations follows.
\nContraction scour for all modelled flows ranged from 0.4 to 0.8 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour ranged from 4.6 to \n7.2 ft. The worst-case abutment scour also occurred at the 500-year discharge. Additional \ninformation on scour depths and depths to armoring are included in the section titled “Scour \nResults”. Scoured-streambed elevations, based on the calculated scour depths, are presented \nin tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure \n8. Scour depths were calculated assuming an infinite depth of erosive material and a \nhomogeneous particle-size distribution.
\nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97388","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Olson, S.A., and Boehmler, E.M., 1997, Level II scour analysis for Bridge 23 (GLOVTH00410023) on Town Highway 41, crossing Sherburne Brook, Glover, Vermont: U.S. Geological Survey Open-File Report 97-388, iv, 48 p., https://doi.org/10.3133/ofr97388.","productDescription":"iv, 48 p.","numberOfPages":"53","costCenters":[],"links":[{"id":169789,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97388.PNG"},{"id":279746,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0388/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Glover","otherGeospatial":"Sherburne Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.25,44.625 ], [ -72.25,44.75 ], [ -72.125,44.75 ], [ -72.125,44.625 ], [ -72.25,44.625 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b1ae4b07f02db6a80f5","contributors":{"authors":[{"text":"Olson, Scott A. 0000-0002-1064-2125 solson@usgs.gov","orcid":"https://orcid.org/0000-0002-1064-2125","contributorId":2059,"corporation":false,"usgs":true,"family":"Olson","given":"Scott","email":"solson@usgs.gov","middleInitial":"A.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240503,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Boehmler, Erick M.","contributorId":96303,"corporation":false,"usgs":true,"family":"Boehmler","given":"Erick","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":240504,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":50004,"text":"ofr97769 - 1997 - Level II scour analysis for Bridge 53 (CHESTH01180053) on Town Highway 118, crossing the Williams River, Chester, Vermont","interactions":[],"lastModifiedDate":"2013-12-17T15:54:38","indexId":"ofr97769","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-769","title":"Level II scour analysis for Bridge 53 (CHESTH01180053) on Town Highway 118, crossing the Williams River, Chester, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nCHESTH01180053 on Town Highway 118 crossing the Williams River, Chester, Vermont \n(figures 1–8). A Level II study is a basic engineering analysis of the site, including a \nquantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). Results of a Level I scour investigation also are included in Appendix E of this \nreport. A Level I investigation provides a qualitative geomorphic characterization of the \nstudy site. Information on the bridge, gleaned from Vermont Agency of Transportation \n(VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is \nfound in Appendix D.\nThe site is in the New England Upland section of the New England physiographic province \nin southeastern Vermont. The 20.8-mi2\n drainage area is in a predominantly rural and \nforested basin. In the vicinity of the study site, the surface cover is predominantly suburban \nwhile the right bank upstream is pasture. There is a house on the right bank downstream and \nVT 103 runs parallel to the river along the left bank.\nIn the study area, the Williams River has an incised, straight channel with a slope of \napproximately 0.005 ft/ft, an average channel top width of 64 ft and an average bank height \nof 7 ft. The channel bed material ranges from sand to boulder with a median grain size (D50) \nof 58.0 mm (0.190 ft). The geomorphic assessment at the time of the Level I and Level II \nsite visit on September 17, 1996, indicated that the reach was stable.\nThe Town Highway 118 crossing of the Williams River is a 43-ft-long, one-lane bridge \nconsisting of one 40-foot steel-beam span (Vermont Agency of Transportation, written \ncommunication, April 6, 1995). The opening length of the structure parallel to the bridge \nface is 37.6 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The \nchannel is skewed approximately 5 degrees to the opening while the computed opening-skew-to-roadway is 10 degrees. \nA scour hole 0.5 ft deeper than the mean thalweg depth was observed at both abutments \nduring the Level I assessment. Scour protection measures at the site include: type-3 stone \nfill (less than 48 inches diameter) along the left bank upstream and downstream and type-2 \nstone fill (less than 36 inches diameter) along the entire base length of the upstream left \nwingwall, at the upstream end of the left abutment, and at the upstream end of the \ndownstream left wingwall. Additional details describing conditions at the site are included \nin the Level II Summary and Appendices D and E.\nScour depths and recommended rock rip-rap sizes were computed using the general \nguidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995) \nfor the 100- and 500-year discharges. In addition, the incipient roadway-overtopping \ndischarge is determined and analyzed as another potential worst-case scour scenario. Total \nscour at a highway crossing is comprised of three components: 1) long-term streambed \ndegradation; 2) contraction scour (due to accelerated flow caused by a reduction in flow \narea at a bridge) and; 3) local scour (caused by accelerated flow around piers and \nabutments). Total scour is the sum of the three components. Equations are available to \ncompute depths for contraction and local scour and a summary of the results of these \ncomputations follows.\nContraction scour for all modelled flows was 0.0 ft. Abutment scour ranged from 5.8 to 6.8 \nft at the left abutment and 9.4 to 14.4 ft at the right abutment. The worst-case abutment \nscour occurred at the incipient roadway-overtopping discharge. Additional information on \nscour depths and depths to armoring are included in the section titled “Scour Results”. \nScoured-streambed elevations, based on the calculated scour depths, are presented in tables \n1 and 2. A cross-section of the scour computed at the bridge is presented in figure 8. Scour \ndepths were calculated assuming an infinite depth of erosive material and a homogeneous \nparticle-size distribution. \nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97769","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Striker, L.K., and Medalie, L., 1997, Level II scour analysis for Bridge 53 (CHESTH01180053) on Town Highway 118, crossing the Williams River, Chester, Vermont: U.S. Geological Survey Open-File Report 97-769, iv, 51 p., https://doi.org/10.3133/ofr97769.","productDescription":"iv, 51 p.","numberOfPages":"56","costCenters":[],"links":[{"id":176433,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97769.PNG"},{"id":279674,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0769/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Chester","otherGeospatial":"Williams River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -73.625,43.25 ], [ -73.625,43.375 ], [ -73.5,43.375 ], [ -73.5,43.25 ], [ -73.625,43.25 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a5b05","contributors":{"authors":[{"text":"Striker, Lora K.","contributorId":41481,"corporation":false,"usgs":true,"family":"Striker","given":"Lora","email":"","middleInitial":"K.","affiliations":[],"preferred":false,"id":240619,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Medalie, Laura 0000-0002-2440-2149 lmedalie@usgs.gov","orcid":"https://orcid.org/0000-0002-2440-2149","contributorId":3657,"corporation":false,"usgs":true,"family":"Medalie","given":"Laura","email":"lmedalie@usgs.gov","affiliations":[{"id":466,"text":"New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240618,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":50028,"text":"ofr97807 - 1997 - Level II scour analysis for Bridge 71 (WODSTH00050071) on Town Highway 5, crossing Kedron Brook, Woodstock, Vermont","interactions":[],"lastModifiedDate":"2013-12-17T15:34:18","indexId":"ofr97807","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-807","title":"Level II scour analysis for Bridge 71 (WODSTH00050071) on Town Highway 5, crossing Kedron Brook, Woodstock, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nWODSTH00050071 on Town Highway 5 crossing Kedron Brook, Woodstock, Vermont \n(figures 1–8). A Level II study is a basic engineering analysis of the site, including a \nquantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). Results of a Level I scour investigation also are included in Appendix E of this \nreport. A Level I investigation provides a qualitative geomorphic characterization of the \nstudy site. Information on the bridge, gleaned from Vermont Agency of Transportation \n(VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is \nfound in Appendix D.\nThe site is in the New England Upland section of the New England physiographic province \nin east-central Vermont. The 16.1-mi2\n drainage area is in a predominantly rural and forested \nbasin. However, the bridge site is within the Village of Woodstock. In the vicinity of the \nstudy site, the surface cover is best described as suburban downstream of the bridge and \nforest and brush upstream of the bridge.\nIn the study area, Kedron Brook has an incised, sinuous channel with a slope of \napproximately 0.03 ft/ft, an average channel top width of 33 ft and an average bank height \nof 11 ft. The predominant channel bed material is cobble with a median grain size (D50) of \n112 mm (0.368 ft). The geomorphic assessment at the time of the Level I and Level II site \nvisit on September 14, 1994, indicated that the reach was vertically degraded. Evidence of \nthe degradation was observed at the outlet of the bridge where the stream bed is 4 ft below \nthe downstream invert of the structure (see figure 6).\nThe Town Highway 5 crossing of Kedron Brook is a 30-ft-long, two-lane bridge/box \nculvert consisting of one 25-foot concrete span (Vermont Agency of Transportation, written \ncommunication, August 3, 1994). The opening length of the structure parallel to the bridge \nface is 23.5 ft.The bridge is supported by vertical, concrete abutments with wingwalls. The \nchannel bed under the bridge is covered entirely by a concrete slab. The channel is skewed \napproximately 45 degrees to the opening and the opening-skew-to-roadway is also 45 \ndegrees.\nScour countermeasures at the site include concrete retaining walls on both the left and right \ndownstream banks extending approximately 130 ft downstream; a drywall constructed of \nstone on the upstream right bank extending to the next bridge upstream; type-2 stone fill \n(less than 36 inches diameter) along the upstream left bank, at the upstream end of the \nupstream right wingwall, and along the base of the retaining wall on the downstream left \nbank; and type-3 stone-fill (less than 48 inches diameter) along the base of the retaining \nwall on the downstream right bank. In addition, the channel under the bridge is concrete. \nFurther details describing conditions at the site are included in the Level II Summary and \nAppendices D and E.\nScour depths and recommended rock rip-rap sizes were computed using the general \nguidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995) \nfor the 100- and 500-year discharges. In addition, the incipient roadway-overtopping \ndischarge is determined and analyzed as another potential worst-case scour scenario. Total \nscour at a highway crossing is comprised of three components: 1) long-term streambed \ndegradation; 2) contraction scour (due to accelerated flow caused by a reduction in flow \narea at a bridge) and; 3) local scour (caused by accelerated flow around piers and \nabutments). Total scour is the sum of the three components. Equations are available to \ncompute depths for contraction and local scour and a summary of the results of these \ncomputations follows.\nContraction scour for all modelled flows ranged from 0.0 to 2.5 ft. The worst-case \ncontraction scour occurred at the incipient roadway-overtopping discharge, which was less \nthan the 100-year discharge. The contraction scour depths do not take the concrete channel \nbed under the bridge into account. Abutment scour ranged from 8.7 to 18.2 ft. The worstcase abutment scour occurred at the 500-year discharge. Additional information on scour \ndepths 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. \nA cross-section of the scour computed at the bridge is presented in figure 8. Scour depths \nwere calculated assuming an infinite depth of erosive material and a homogeneous particlesize distribution. \nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97807","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and the Federal Highway Administration","usgsCitation":"Olson, S., and Ayotte, J., 1997, Level II scour analysis for Bridge 71 (WODSTH00050071) on Town Highway 5, crossing Kedron Brook, Woodstock, Vermont: U.S. Geological Survey Open-File Report 97-807, 51 p., https://doi.org/10.3133/ofr97807.","productDescription":"51 p.","onlineOnly":"N","costCenters":[],"links":[{"id":161676,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/usgs_thumb.jpg"},{"id":279656,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0807/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.625,43.50 ], [ -72.625,43.75 ], [ -72.5,43.75 ], [ -72.5,43.50 ], [ -72.625,43.50 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b16e4b07f02db6a56df","contributors":{"authors":[{"text":"Olson, S.A.","contributorId":58681,"corporation":false,"usgs":true,"family":"Olson","given":"S.A.","email":"","affiliations":[],"preferred":false,"id":240663,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Ayotte, J. D.","contributorId":96667,"corporation":false,"usgs":true,"family":"Ayotte","given":"J. D.","affiliations":[],"preferred":false,"id":240664,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49932,"text":"ofr97377 - 1997 - Level II scour analysis for Bridge 41 (ROCKTH00390041) on Town Highway 39, crossing the Saxtons River, Rockingham, Vermont","interactions":[],"lastModifiedDate":"2013-12-20T11:11:59","indexId":"ofr97377","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-377","title":"Level II scour analysis for Bridge 41 (ROCKTH00390041) on Town Highway 39, crossing the Saxtons River, Rockingham, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nROCKTH00390041 on Town Highway 39 crossing the Saxtons River, Rockingham, \nVermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including \na quantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). Results of a Level I scour investigation also are included in Appendix E of this \nreport. A Level I investigation provides a qualitative geomorphic characterization of the \nstudy site. Information on the bridge, gleaned from Vermont Agency of Transportation \n(VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is \nfound in Appendix D.
\nThe site is in the New England Upland section of the New England physiographic province \nin southeastern Vermont. The 57.4-mi2\n drainage area is in a predominantly rural and \nforested basin. In the vicinity of the study site, the surface cover consists of forest on the left \nbank and pasture with some trees on the right bank.
\nIn the study area, the Saxtons River has an sinuous channel with a slope of approximately \n0.009 ft/ft, an average channel top width of 112 ft and an average bank height of 10 ft. The \nchannel bed material ranges from sand to cobbles with a median grain size (D50) of 103 mm \n(0.339 ft). The geomorphic assessment at the time of the Level I and Level II site visit on \nAugust 15, 1996, indicated that the reach was laterally unstable. There are wide point bars, \ncut-banks with fallen trees, and areas of localized channel scour along the left bank, where \nthere is bedrock exposure at the surface.
\nThe Town Highway 39 crossing of the Saxtons River is an 85-ft-long, one-lane bridge \nconsisting of one 82-foot steel-beam span (Vermont Agency of Transportation, written \ncommunication, March 31, 1995). The bridge is supported by vertical, concrete abutments \nwithout wingwalls. The channel is skewed approximately 30 degrees to the opening while \nthe opening-skew-to-roadway is zero degrees.
\nA scour hole 3 ft deeper than the mean thalweg depth was observed during the Level I \nassessment along the left side of the channel under the bridge exposing the left abutment \nfooting 5.5 feet. The only scour protection measure at the site was type-2 stone fill (less \nthan 36 inches diameter) on the left banks upstream and downstream and the left abutment \nwall. Additional details describing conditions at the site are included in the Level II \nSummary and Appendices D and E.
\nScour depths and recommended rock rip-rap sizes were computed using the general \nguidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). \nTotal scour at a highway crossing is comprised of three components: 1) long-term \nstreambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction \nin flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and \nabutments). Total scour is the sum of the three components. Equations are available to \ncompute depths for contraction and local scour and a summary of the results of these \ncomputations follows.
\nContraction scour for all modelled flows ranged from 2.2 to 3.8 feet. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour ranged from 21.4 to \n23.2 feet and 26.2 to 32.4 feet at the left and right abutments respectively. The worst-case \nabutment scour occurred for the right abutment at the incipient overtopping discharge. \nAdditional information on scour depths and depths to armoring are included in the section \ntitled “Scour Results”. Scoured-streambed elevations, based on the calculated scour depths, \nare presented in tables 1 and 2. A cross-section of the scour computed at the bridge is \npresented in figure 8. Bedrock was exposed at the surface in some areas of the channel and \npotentially is located at a shallower depth than the scour depths indicated above. \nNevertheless, scour depths were calculated assuming an infinite depth of erosive material \nand a homogeneous particle-size distribution.
\nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97377","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Boehmler, E.M., and Degnan, J.R., 1997, Level II scour analysis for Bridge 41 (ROCKTH00390041) on Town Highway 39, crossing the Saxtons River, Rockingham, Vermont: U.S. Geological Survey Open-File Report 97-377, iv, 49 p., https://doi.org/10.3133/ofr97377.","productDescription":"iv, 49 p.","numberOfPages":"54","costCenters":[],"links":[{"id":170527,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/usgs_thumb.jpg"},{"id":279750,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0377/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Rockingham","otherGeospatial":"Saxtons River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,43.5 ], [ -72.75,43.625 ], [ -72.625,43.625 ], [ -72.625,43.5 ], [ -72.75,43.5 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a6197","contributors":{"authors":[{"text":"Boehmler, Erick M.","contributorId":96303,"corporation":false,"usgs":true,"family":"Boehmler","given":"Erick","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":240496,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Degnan, James R. 0000-0002-5665-9010 jrdegnan@usgs.gov","orcid":"https://orcid.org/0000-0002-5665-9010","contributorId":498,"corporation":false,"usgs":true,"family":"Degnan","given":"James","email":"jrdegnan@usgs.gov","middleInitial":"R.","affiliations":[{"id":466,"text":"New England Water Science Center","active":true,"usgs":true},{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240495,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49929,"text":"ofr97374 - 1997 - Level II scour analysis for Bridge 8 (ANDOTH00010008) on Town Highway 1, crossing Andover Branch, Andover, Vermont","interactions":[],"lastModifiedDate":"2016-08-25T13:03:16","indexId":"ofr97374","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-374","title":"Level II scour analysis for Bridge 8 (ANDOTH00010008) on Town Highway 1, crossing Andover Branch, Andover, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure ANDOTH00010008 on Town Highway 1 crossing the Andover Branch, 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 south-central Vermont. The 5.30-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover along the immediate banks, both upstream and downstream of the bridge, is grass while farther upstream and downstream, the surface cover is primarily forest.
In the study area, the Andover Branch has an incised, straight channel with a slope of approximately 0.01 ft/ft, an average channel top width of 35 ft and an average bank height of 3 ft. The channel bed material ranges from gravel to boulder with a median grain size (D50) of 63.6 mm (0.209 ft). The geomorphic assessment at the time of the Level I and Level II site visit on August 27, 1996, indicated that the reach was stable.
The Town Highway 1 crossing of the Andover Branch is a 54-ft-long, two-lane bridge consisting of one 51-foot steel-beam span (Vermont Agency of Transportation, written communication, March 28, 1995). The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 45 degrees to the opening while the opening-skew-to-roadway is 30 degrees.
A scour hole 0.7 ft deeper than the mean thalweg depth was observed approximately 52 feet downstream of the downstream face of the bridge during the Level I assessment. Scour countermeasures at the site include type-2 stone fill (less than 36 inches diameter) along the entire base length of the left and right abutments and along the left bank from 65 ft to 89 ft upstream. Type-1 stone fill was found along the right bank from the bridge to 47 ft upstream and along the left bank from 40 ft to 65 ft upstream. 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 0.1 ft. The worst case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 5.0 to 8.1 ft along the left abutment and from 2.1 to 4.6 ft along the right abutment. 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.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97374","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Flynn, R.H., and Wild, E.C., 1997, Level II scour analysis for Bridge 8 (ANDOTH00010008) on Town Highway 1, crossing Andover Branch, Andover, Vermont: U.S. Geological Survey Open-File Report 97-374, iv, 53 p., https://doi.org/10.3133/ofr97374.","productDescription":"iv, 53 p.","numberOfPages":"58","costCenters":[],"links":[{"id":170524,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97374.PNG"},{"id":279753,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0374/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Andover","otherGeospatial":"Andover Branch","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,43.25 ], [ -72.75,43.375 ], [ -72.625,43.375 ], [ -72.625,43.25 ], [ -72.75,43.25 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b16e4b07f02db6a56b4","contributors":{"authors":[{"text":"Flynn, Robert H. rflynn@usgs.gov","contributorId":2137,"corporation":false,"usgs":true,"family":"Flynn","given":"Robert","email":"rflynn@usgs.gov","middleInitial":"H.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240491,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Wild, Emily C. 0000-0001-6157-7629 ecwild@usgs.gov","orcid":"https://orcid.org/0000-0001-6157-7629","contributorId":1810,"corporation":false,"usgs":true,"family":"Wild","given":"Emily","email":"ecwild@usgs.gov","middleInitial":"C.","affiliations":[{"id":5081,"text":"Libraries","active":false,"usgs":true}],"preferred":false,"id":240490,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49960,"text":"ofr97581 - 1997 - Level II scour analysis for Bridge 16 (CHESVT01030016) on State Route 103, crossing the Williams River, Chester, Vermont","interactions":[],"lastModifiedDate":"2013-12-18T14:38:25","indexId":"ofr97581","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-581","title":"Level II scour analysis for Bridge 16 (CHESVT01030016) on State Route 103, crossing the Williams River, Chester, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nCHESVT01030016 on State Route 103 crossing the Williams River, Chester, Vermont \n(figures 1–8). A Level II study is a basic engineering analysis of the site, including a \nquantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). Results of a Level I scour investigation also are included in Appendix E of this \nreport. A Level I investigation provides a qualitative geomorphic characterization of the \nstudy site. Information on the bridge, gleaned from Vermont Agency of Transportation \n(VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is \nfound in Appendix D.
\nThe site is in the New England Upland section of the New England physiographic province \nin southeastern Vermont. The 15.1-mi2\n drainage area is in a predominantly rural and \nforested basin. In the vicinity of the study site, the surface cover is pasture except for the \ndownstream right overbank which is forested.
\nIn the study area, the Williams River has an incised, straight channel with a slope of \napproximately 0.008 ft/ft, an average channel top width of 56 ft and an average bank height \nof 6 ft. The channel bed material ranges from gravel to cobbles with a median grain size \n(D50) of 67.5 mm (0.222 ft). The geomorphic assessment at the time of the Level I and \nLevel II site visit on September 16, 1996, indicated that the reach was stable.
\nThe State Route 103 crossing of the Williams River is a 162-ft-long, two-lane bridge \nconsisting of three steel-beam spans (Vermont Agency of Transportation, written \ncommunication, March 13, 1995). The opening length of the structure parallel to the bridge \nface is 157.7 ft.The bridge is supported by vertical, concrete abutments and piers with no \nwingwalls. The channel is skewed approximately 55 degrees to the opening while the \nopening-skew-to-roadway is also 55 degrees.
\nThe scour protection measures at the site included type-4 stone fill (less than 60 inches \ndiameter) along the upstream left bank. There was type-3 stone fill (less than 48 inches \ndiameter) along the upstream right bank and both spill-through embankments and both \ndownstream banks. There was type-1 stone fill (less than 12 inches diameter) along the \nupstream right and downstream left road embankments. Additional details describing \nconditions at the site are included in the Level II Summary and Appendices D and E.
\nScour depths and recommended rock rip-rap sizes were computed using the general \nguidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). \nTotal scour at a highway crossing is comprised of three components: 1) long-term \nstreambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction \nin flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and \nabutments). Total scour is the sum of the three components. Equations are available to \ncompute depths for contraction and local scour and a summary of the results of these \ncomputations follows.
\nContraction scour for all modelled flows was 0.0. Abutment scour ranged from 6.4 to 9.0 ft. \nThe worst-case abutment scour occurred at the 500-year discharge. Pier scour ranged from \n7.9 to 10.1 ft. The worst-case pier scour occurred at the incipient-overtopping discharge for \nboth piers. Additional information on scour depths and depths to armoring are included in \nthe section titled “Scour Results”. Scoured-streambed elevations, based on the calculated \nscour depths, are presented in tables 1 and 2. A cross-section of the scour computed at the \nbridge is presented in figure 8. Scour depths were calculated assuming an infinite depth of \nerosive material and a homogeneous particle-size distribution.
\nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97581","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Ivanoff, M.A., and Hammond, R.E., 1997, Level II scour analysis for Bridge 16 (CHESVT01030016) on State Route 103, crossing the Williams River, Chester, Vermont: U.S. Geological Survey Open-File Report 97-581, iv, 54 p., https://doi.org/10.3133/ofr97581.","productDescription":"iv, 54 p.","numberOfPages":"59","costCenters":[],"links":[{"id":175619,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97581.GIF"},{"id":279718,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0581/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Chester","otherGeospatial":"Williams River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,43.25 ], [ -72.75,43.375 ], [ -72.5,43.375 ], [ -72.5,43.25 ], [ -72.75,43.25 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b1ae4b07f02db6a827c","contributors":{"authors":[{"text":"Ivanoff, Michael A.","contributorId":27105,"corporation":false,"usgs":true,"family":"Ivanoff","given":"Michael","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":240543,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Hammond, Robert E.","contributorId":61862,"corporation":false,"usgs":true,"family":"Hammond","given":"Robert","email":"","middleInitial":"E.","affiliations":[],"preferred":false,"id":240544,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49947,"text":"ofr97404 - 1997 - Level II scour analysis for Bridge 81 (NFIETH00PL0081) on Pleasant Street, crossing Union Brook, Northfield, Vermont","interactions":[],"lastModifiedDate":"2013-12-19T11:11:41","indexId":"ofr97404","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-404","title":"Level II scour analysis for Bridge 81 (NFIETH00PL0081) on Pleasant Street, crossing Union Brook, Northfield, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nNFIETH00PL0081 on Pleasant Street crossing Union Brook, Northfield, Vermont (figures \n1–8). A Level II study is a basic engineering analysis of the site, including a quantitative \nanalysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of \na Level I scour investigation also are included in Appendix E of this report. A Level I \ninvestigation provides a qualitative geomorphic characterization of the study site. \nInformation on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) \nfiles, was compiled prior to conducting Level I and Level II analyses and is found in \nAppendix D.\nThe site is in the Green Mountain section of the New England physiographic province in \ncentral Vermont. The 6.1-mi2\n drainage area is in a predominantly rural and forested basin. \nThe bridge site is located within a suburban setting in the Town of Northfield with homes, \nlawns, and pavement on the overbanks. There are trees and brush along the immediate \nbanks.\nIn the study area, Union Brook has an incised, straight channel with a slope of \napproximately 0.01 ft/ft, an average channel top width of 41 ft and an average bank height \nof 4 ft. The channel bed material ranges from gravel to boulders with a median grain size \n(D50) of 47.7 mm (0.157 ft). The geomorphic assessment at the time of the Level I and \nLevel II site visit on July 24, 1996, indicated that the reach was stable.\nThe Pleasant Street crossing of Union Brook is a 34-ft-long, two-lane bridge consisting of \none 29-foot steel-beam span (Vermont Agency of Transportation, written communication, \nOctober 13, 1995). The opening length of the structure parallel to the bridge face is 26.6 ft. \nThe bridge is supported by vertical, concrete abutments with wingwalls. The channel is \nskewed approximately 25 degrees to the opening while the opening-skew-to-roadway is 30 \ndegrees.\nA scour hole 0.5 ft deeper than the mean thalweg depth was observed along the upstream \nleft wingwall and upstream end of the left abutment during the Level I assessment. The \nscour protection measures at the site were type-1 stone fill (less than 12 inches diameter) \nalong the upstream left bank, the upstream left wingwall, and the downstream left bank, and \ntype-2 stone fill (less than 36 inches diameter) along the downstream right bank. There is \nalso a laid-up stone wall in front of the downstream left wingwall. Additional details \ndescribing conditions at the site are included in the Level II Summary and Appendices D \nand E.\nScour depths and recommended rock rip-rap sizes were computed using the general \nguidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). \nTotal scour at a highway crossing is comprised of three components: 1) long-term \nstreambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction \nin flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and \nabutments). Total scour is the sum of the three components. Equations are available to \ncompute depths for contraction and local scour and a summary of the results of these \ncomputations follows.\nContraction scour for all modelled flows ranged from 0.0 to 0.5 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour ranged from 4.2 to \n13.3 ft. The worst-case abutment scour occurred at the 500-year discharge. Additional \ninformation on scour depths and depths to armoring are included in the section titled “Scour \nResults”. Scoured-streambed elevations, based on the calculated scour depths, are presented \nin tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure \n8. Scour depths were calculated assuming an infinite depth of erosive material and a \nhomogeneous particle-size distribution. \nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97404","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Burns, R.L., and Medalie, L., 1997, Level II scour analysis for Bridge 81 (NFIETH00PL0081) on Pleasant Street, crossing Union Brook, Northfield, Vermont: U.S. Geological Survey Open-File Report 97-404, iv, 51 p., https://doi.org/10.3133/ofr97404.","productDescription":"iv, 51 p.","numberOfPages":"56","costCenters":[],"links":[{"id":176358,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97404.PNG"},{"id":279736,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0404/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Northfield","otherGeospatial":"Union Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,44.125 ], [ -72.75,44.25 ], [ -72.625,44.25 ], [ -72.625,44.125 ], [ -72.75,44.125 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b16e4b07f02db6a55d5","contributors":{"authors":[{"text":"Burns, Ronda L.","contributorId":71602,"corporation":false,"usgs":true,"family":"Burns","given":"Ronda","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":240520,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Medalie, Laura 0000-0002-2440-2149 lmedalie@usgs.gov","orcid":"https://orcid.org/0000-0002-2440-2149","contributorId":3657,"corporation":false,"usgs":true,"family":"Medalie","given":"Laura","email":"lmedalie@usgs.gov","affiliations":[{"id":466,"text":"New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240519,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49935,"text":"ofr97386 - 1997 - Level II scour analysis for Bridge 43 (CHELTH00460043) on Town Highway 46, crossing Jail Brook, Chelsea, Vermont","interactions":[],"lastModifiedDate":"2013-12-20T10:15:18","indexId":"ofr97386","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-386","title":"Level II scour analysis for Bridge 43 (CHELTH00460043) on Town Highway 46, crossing Jail Brook, Chelsea, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nCHELTH00460043 on Town Highway 46 crossing Jail Brook, Chelsea, Vermont (figures \n1–8). A Level II study is a basic engineering analysis of the site, including a quantitative \nanalysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of \na Level I scour investigation also are included in Appendix E of this report. A Level I \ninvestigation provides a qualitative geomorphic characterization of the study site. \nInformation on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) \nfiles, was compiled prior to conducting Level I and Level II analyses and is found in \nAppendix D.
\nThe site is in the New England Upland section of the New England physiographic province \nin central Vermont. The 4.68-mi2\n drainage area is in a predominantly rural and forested \nbasin. In the vicinity of the study site, the surface cover is best described as suburban with \nhomes, lawns, and a few trees.
\nIn the study area, Jail Brook has an incised, straight channel with a slope of approximately \n0.02 ft/ft, an average channel top width of 32 ft and an average bank height of 6 ft. The \nchannel bed material ranges from coarse sand to boulder with a median grain size (D50) of \n43.0 mm (0.141 ft). The geomorphic assessment at the time of the Level I and Level II site \nvisit on November 18, 1994, indicated that the reach was stable.
\nThe Town Highway 46 crossing of Jail Brook is a 27-ft-long, two-lane bridge consisting of \none 23-foot concrete span (Vermont Agency of Transportation, written communication, \nAugust 25, 1994). The opening length of the structure parallel to the bridge face is 22.8 \nft.The bridge is supported by vertical, concrete abutments with wingwalls. The channel is \nskewed approximately zero degrees to the opening and the opening-skew-to-roadway is \nalso zero degrees.
\nChannel scour was not observed. However, the left abutment footing was exposed one foot. \nScour countermeasures at the site consisted of type-2 stone fill (less than 36 inches \ndiameter) on the banks and road embankments upstream and downstream of the bridge. \nAdditional details describing conditions at the site are included in the Level II Summary \nand Appendices D and E.
\nScour depths and recommended rock rip-rap sizes were computed using the general \nguidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). \nTotal scour at a highway crossing is comprised of three components: 1) long-term \nstreambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction \nin flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and \nabutments). Total scour is the sum of the three components. Equations are available to \ncompute depths for contraction and local scour and a summary of the results of these \ncomputations follows.
\nContraction scour for all modelled flows ranged from 1.1 to 1.2 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour ranged from 5.0 to \n6.5 ft at the left abutment and 4.7 to 6.2 ft at the right abutment. The worst-case abutment \nscour occurred at the 500-year discharge. Additional information on scour depths and \ndepths to armoring are included in the section titled “Scour Results”. Scoured-streambed \nelevations, 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 \ncalculated assuming an infinite depth of erosive material and a homogeneous particle-size \ndistribution.
\nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97386","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Olson, S.A., 1997, Level II scour analysis for Bridge 43 (CHELTH00460043) on Town Highway 46, crossing Jail Brook, Chelsea, Vermont: U.S. Geological Survey Open-File Report 97-386, iv, 48 p., https://doi.org/10.3133/ofr97386.","productDescription":"iv, 48 p.","numberOfPages":"53","costCenters":[],"links":[{"id":169725,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97386.PNG"},{"id":279748,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0386/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Chelsea","otherGeospatial":"Jail Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.5,43.875 ], [ -72.5,44.0 ], [ -72.375,44.0 ], [ -72.375,43.875 ], [ -72.5,43.875 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a5f8e","contributors":{"authors":[{"text":"Olson, Scott A. 0000-0002-1064-2125 solson@usgs.gov","orcid":"https://orcid.org/0000-0002-1064-2125","contributorId":2059,"corporation":false,"usgs":true,"family":"Olson","given":"Scott","email":"solson@usgs.gov","middleInitial":"A.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240500,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":50009,"text":"ofr97773 - 1997 - Level II scour analysis for Bridge 38 (JERITH0020038) on Town Highway 20, crossing the Lee River, Jericho, Vermont","interactions":[],"lastModifiedDate":"2016-08-25T14:51:05","indexId":"ofr97773","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-773","title":"Level II scour analysis for Bridge 38 (JERITH0020038) on Town Highway 20, crossing the Lee River, Jericho, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure JERITH00200038 on Town Highway 20 crossing the Lee River, Jericho, 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, obtained 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 and the Champlain section of the St. Lawrence physiographic province in northwestern Vermont. The 12.9-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover on the upstream and downstream right overbank is pasture while the immediate banks have dense woody vegetation. The surface cover on the upstream and downstream left overbank is forested.
In the study area, the Lee River has an incised, sinuous channel with a slope of approximately 0.02 ft/ft, an average channel top width of 89 ft and an average bank height of 14 ft. The channel bed material ranges from sand to boulder with a median grain size (D50) of 45.9 mm (0.151 ft). The geomorphic assessment at the time of the Level I and Level II site visit on July 2, 1996, indicated that the reach was stable.
The Town Highway 20 crossing of the Lee River is a 49-ft-long, one-lane bridge consisting of a steel through truss span (Vermont Agency of Transportation, written communication, December 12, 1995). The opening length of the structure parallel to the bridge face is 44 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 10 degrees to the opening while the computed opening-skew-toroadway is 5 degrees.
A scour hole 1 ft deeper than the mean thalweg depth was observed in the center of the channel during the Level I assessment. Scour countermeasures at the site include type-1 stone fill (less than 12 inches diameter) at the downstream left road embankment. Type-2 stone fill (less than 36 inches diameter) protects the upstream left wingwall, the upstream and downstream right wingwalls and the upstream end of the right abutment. Type-3 stone fill (less than 48 inches diameter) protects the left 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. 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 zero. Abutment scour ranged from 4.9 to 10.7 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.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97773","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Wild, E.C., and Degnan, J.R., 1997, Level II scour analysis for Bridge 38 (JERITH0020038) on Town Highway 20, crossing the Lee River, Jericho, Vermont: U.S. Geological Survey Open-File Report 97-773, iv, 48 p., https://doi.org/10.3133/ofr97773.","productDescription":"iv, 48 p.","numberOfPages":"53","costCenters":[],"links":[{"id":176807,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97773.PNG"},{"id":279670,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0773/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Jericho","otherGeospatial":"Lee River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,43.5 ], [ -72.75,43.625 ], [ -72.625,43.625 ], [ -72.625,43.5 ], [ -72.75,43.5 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a6271","contributors":{"authors":[{"text":"Wild, Emily C. 0000-0001-6157-7629 ecwild@usgs.gov","orcid":"https://orcid.org/0000-0001-6157-7629","contributorId":1810,"corporation":false,"usgs":true,"family":"Wild","given":"Emily","email":"ecwild@usgs.gov","middleInitial":"C.","affiliations":[{"id":5081,"text":"Libraries","active":false,"usgs":true}],"preferred":false,"id":240628,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Degnan, James R. 0000-0002-5665-9010 jrdegnan@usgs.gov","orcid":"https://orcid.org/0000-0002-5665-9010","contributorId":498,"corporation":false,"usgs":true,"family":"Degnan","given":"James","email":"jrdegnan@usgs.gov","middleInitial":"R.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true},{"id":466,"text":"New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240627,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49939,"text":"ofr97390 - 1997 - Level II scour analysis for Bridge 24 (MANCUS00070024) on U.S. Route 7, crossing Lye Brook, Manchester, Vermont","interactions":[],"lastModifiedDate":"2013-12-20T09:38:07","indexId":"ofr97390","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-390","title":"Level II scour analysis for Bridge 24 (MANCUS00070024) on U.S. Route 7, crossing Lye Brook, Manchester, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nMANCUS00070024 on U.S. Route 7 crossing Lye Brook, Manchester, Vermont (figures \n1–8). A Level II study is a basic engineering analysis of the site, including a quantitative \nanalysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of \na Level I scour investigation also are included in Appendix E of this report. A Level I \ninvestigation provides a qualitative geomorphic characterization of the study site. \nInformation on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) \nfiles, was compiled prior to conducting Level I and Level II analyses and is found in \nAppendix D.
\nThe site is in the Taconic section of the New England physiographic province in \nsouthwestern Vermont. The 8.13-mi2\n drainage area is in a predominantly rural and forested \nbasin. In the vicinity of the study site, the primary surface cover consists of brush and trees.
\nIn the study area, Lye Brook has an incised, sinuous channel with a slope of approximately \n0.03 ft/ft, an average channel top width of 66 ft and an average bank height of 11 ft. The \nchannel bed material ranges from gravel to boulder with a median grain size (D50) of 90.0 \nmm (0.295 ft). The geomorphic assessment at the time of the Level I and Level II site visit \non August 6, 1996, indicated that the reach was stable. Although, the immediate reach is \nconsidered stable, upstream of the bridge the Lye Brook valley is very steep (0.05 ft/ft). \nExtreme events in a valley this steep may quickly reveal the instability of the channel. In the \nFlood Insurance Study for the Town of Manchester (Federal Emergency Management \nAgency, January, 1985), Lye Brook’s overbanks were described as “boulder strewn” after \nthe August 1976 flood.
\nThe U.S. Route 7 crossing of Lye Brook is a 28-ft-long, two-lane bridge consisting of one \n25-foot concrete span (Vermont Agency of Transportation, written communication, \nSeptember 28, 1995). The bridge is supported by vertical, concrete abutments with \nwingwalls. The channel is skewed approximately 45 degrees to the opening while the \nopening-skew-to-roadway is 55 degrees.
\nAt the time of construction, the downstream channel was relocated (written communication, \nDan Landry, VTAOT, January 2, 1997). A levee on the downstream right bank was also \nconstructed and is protected by type-4 stone-fill (less than 60 inches diameter) extending \nfrom the bridge to more than 300 feet downstream. Type-2 stone fill (less than 36 inches \ndiameter) covers the downstream right bank from the bridge to more than 300 feet \ndownstream. Type-2 stone-fill also extends from the bridge to 220 feet upstream on both \nupstream banks. Additional details describing conditions at the site are included in the \nLevel II Summary and Appendices D and E.
\nScour depths and recommended rock rip-rap sizes were computed using the general \nguidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995) \nfor the 100- and 500-year discharges. In addition, the incipient roadway-overtopping \ndischarge is analyzed since it has the potential of being the worst-case scour scenario. Total \nscour at a highway crossing is comprised of three components: 1) long-term streambed \ndegradation; 2) contraction scour (due to accelerated flow caused by a reduction in flow \narea at a bridge) and; 3) local scour (caused by accelerated flow around piers and \nabutments). Total scour is the sum of the three components. Equations are available to \ncompute depths for contraction and local scour and a summary of the results of these \ncomputations follows.
\nContraction scour for all modelled flows ranged from 1.0 to 1.6 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour computations for the \nleft abutment ranged from 14.5 to 16.1 ft. with the worst-case occurring at the 100-year \ndischarge. Abutment scour computations for the right abutment ranged from 6.9 to 10.4 ft. \nwith the worst-case occurring at the 500-year discharge. Additional information on scour \ndepths 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. \nA cross-section of the scour computed at the bridge is presented in figure 8. Scour depths \nwere calculated assuming an infinite depth of erosive material and a homogeneous particle-size distribution.
\nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97390","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Olson, S.A., 1997, Level II scour analysis for Bridge 24 (MANCUS00070024) on U.S. Route 7, crossing Lye Brook, Manchester, Vermont: U.S. Geological Survey Open-File Report 97-390, iv, 52 p., https://doi.org/10.3133/ofr97390.","productDescription":"iv, 52 p.","numberOfPages":"57","costCenters":[],"links":[{"id":169791,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/usgs_thumb.jpg"},{"id":279744,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0390/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Manchester","otherGeospatial":"Lye Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -73.125,43.125 ], [ -73.125,43.25 ], [ -73.0,43.25 ], [ -73.0,43.125 ], [ -73.125,43.125 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b19e4b07f02db6a7f71","contributors":{"authors":[{"text":"Olson, Scott A. 0000-0002-1064-2125 solson@usgs.gov","orcid":"https://orcid.org/0000-0002-1064-2125","contributorId":2059,"corporation":false,"usgs":true,"family":"Olson","given":"Scott","email":"solson@usgs.gov","middleInitial":"A.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240506,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49940,"text":"ofr97391 - 1997 - Level II scour analysis for Bridge 49 (FFIETH00290049) on Town Highway29, crossing Black Creek, Fairfield, Vermont","interactions":[],"lastModifiedDate":"2013-12-19T14:20:24","indexId":"ofr97391","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-391","title":"Level II scour analysis for Bridge 49 (FFIETH00290049) on Town Highway29, crossing Black Creek, Fairfield, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nFFIETH00290049 on Town Highway 29 crossing Black Creek, Fairfield, Vermont (figures \n1–8). A Level II study is a basic engineering analysis of the site, including a quantitative \nanalysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of \na Level I scour investigation also are included in Appendix E of this report. A Level I \ninvestigation provides a qualitative geomorphic characterization of the study site. \nInformation on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) \nfiles, was compiled prior to conducting Level I and Level II analyses and is found in \nAppendix D.\nThe site is in the Green Mountain section of the New England physiographic province in \nnorthwestern Vermont. The 83.5-mi2\n drainage area is in a predominantly rural and forested \nbasin. There is agricultural land in the basin as well, especially along the immediate river \nvalley. In the vicinity of the study site, the surface cover is pasture except for on the \ndownstream right bank which has row crops.\nIn the study area, Black Creek has an incised, meandering channel with a slope of \napproximately 0.0005 ft/ft, an average channel top width of 85 ft and an average bank \nheight of 9 ft. The channel bed material ranges from sand to cobble with a median grain size \n(D50) of 3.23 mm (0.0106 ft). The geomorphic assessment at the time of the Level I and \nLevel II site visit on July 13, 1995, indicated that the reach was laterally unstable. This \nassessment was due to apparent long term lateral movement of the channel in the vicinity of \nthe bridge.\nThe Town Highway 29 crossing of Black Creek is a 48-ft-long, one-lane bridge consisting \nof one 45-foot steel pony thru-truss type span (Vermont Agency of Transportation, written \ncommunication, March 8, 1995). The opening length of the structure parallel to the bridge \nface is 42.5 ft.The bridge is supported by vertical, concrete abutments. The channel is \nskewed approximately 30 degrees to the opening while the opening-skew-to-roadway is \nzero degrees. \nChannel scour, approximately 6 ft deeper than the mean thalweg depth, was observed \nthrough the immediate channel reach including underneath the bridge. Type-2 stone fill \n(less than 36 inches diameter) has been placed as a scour countermeasure along both \nabutments, on the channel bed under the bridge and along immediate channel banks \nupstream and downstream of the bridge. Additional details describing conditions at the site \nare included in the Level II Summary and Appendices D and E.\nScour depths and recommended rock rip-rap sizes were computed using the general \nguidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). \nTotal scour at a highway crossing is comprised of three components: 1) long-term \nstreambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction \nin flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and \nabutments). Total scour is the sum of the three components. Equations are available to \ncompute depths for contraction and local scour and a summary of the results of these \ncomputations follows.\nContraction scour for all modelled flows ranged from 0.0 to 4.4 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour ranged from 7.5 to \n14.3 ft and 12.2 to 16.3 ft on the left and right abutments respectively. The worst-case \nabutment scour occurred at the 500-year discharge. Additional information on scour depths \nand 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. \nA cross-section of the scour computed at the bridge is presented in figure 8. Scour depths \nwere calculated assuming an infinite depth of erosive material and a homogeneous particlesize distribution. \nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97391","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Olson, S.A., 1997, Level II scour analysis for Bridge 49 (FFIETH00290049) on Town Highway29, crossing Black Creek, Fairfield, Vermont: U.S. Geological Survey Open-File Report 97-391, iv, 52 p., https://doi.org/10.3133/ofr97391.","productDescription":"iv, 52 p.","numberOfPages":"57","costCenters":[],"links":[{"id":169792,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97391.PNG"},{"id":279743,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0391/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Fairfield","otherGeospatial":"Black Creek","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -73.0,44.75 ], [ -73.0,44.875 ], [ -72.875,44.875 ], [ -72.875,44.75 ], [ -73.0,44.75 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a5fb9","contributors":{"authors":[{"text":"Olson, Scott A. 0000-0002-1064-2125 solson@usgs.gov","orcid":"https://orcid.org/0000-0002-1064-2125","contributorId":2059,"corporation":false,"usgs":true,"family":"Olson","given":"Scott","email":"solson@usgs.gov","middleInitial":"A.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240507,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49941,"text":"ofr97393 - 1997 - Level II scour analysis for Bridge 36 (ANDOVT00110036) on VT 11, crossing Middle Branch Williams River, Andover, Vermont","interactions":[],"lastModifiedDate":"2013-12-19T14:10:14","indexId":"ofr97393","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-393","title":"Level II scour analysis for Bridge 36 (ANDOVT00110036) on VT 11, crossing Middle Branch Williams River, Andover, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nANDOVT00110036 on State Route 11 crossing the Middle Branch Williams River, \nAndover, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, \nincluding a quantitative analysis of stream stability and scour (U.S. Department of \nTransportation, 1993). Results of a Level I scour investigation also are included in \nAppendix E of this report. A Level I investigation provides a qualitative geomorphic \ncharacterization of the study site. Information on the bridge, gleaned from Vermont Agency \nof Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II \nanalyses and is found in Appendix D.\nThe site is in the Green Mountain section of the New England physiographic province in \nsouth-central Vermont. The 5.10-mi2\n drainage area is in a predominantly rural and forested \nbasin. In the vicinity of the study site, the surface cover is pasture on the upstream left bank \nand forested elsewhere throughout the reach.\nIn the study area, the Middle Branch Williams River has an incised, sinuous channel with a \nslope of approximately 0.02 ft/ft, an average channel top width of 38 ft and an average bank \nheight of 2 ft. The channel bed material ranges from sand to boulders with a median grain \nsize (D50) of 60.1 mm (0.197 ft). The geomorphic assessment at the time of the Level I and \nLevel II site visit on August 28, 1996, indicated that the reach was laterally unstable due to \na cut-bank on the left bank upstream, side bar formation on the left bank upstream, and a \ncombination of side bar formation and erosion occurring on the downstream right bank.\nThe State Route 11 crossing of the Middle Branch Williams River is a 28-ft-long, two-lane \nbridge consisting of one 25-foot concrete-beam span (Vermont Agency of Transportation, \nwritten communication, March 28, 1995). The opening length of the structure parallel to the \nbridge face is 25.3 ft.The bridge is supported by vertical, concrete abutments with \nwingwalls. The channel is skewed approximately 30 degrees to the opening and the \nopening-skew-to-roadway is also 30 degrees. \nA scour hole 0.5 ft deeper than the mean thalweg depth was observed 5 feet upstream of the \nbridge during the Level I assessment. Scour protection measures at the site include: type-2 \nstone fill (less than 36 inches diameter) along the left bank upstream, and type-4 stone fill \n(less than 60 inches diameter) along the entire base length of the upstream left wingwall, \nand at the upstream end of the upstream right wing wall. Additional details describing \nconditions at the site are included in the Level II Summary and Appendices D and E.\nScour depths and recommended rock rip-rap sizes were computed using the general \nguidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). \nTotal scour at a highway crossing is comprised of three components: 1) long-term \nstreambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction \nin flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and \nabutments). Total scour is the sum of the three components. Equations are available to \ncompute depths for contraction and local scour and a summary of the results of these \ncomputations follows.\nContraction scour for all modelled flows ranged from 0.0 to 2.8 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour ranged from 9.5 to \n13.7 ft. The worst-case abutment scour also occurred at the 500-year discharge. Additional \ninformation on scour depths and depths to armoring are included in the section titled “Scour \nResults”. Scoured-streambed elevations, based on the calculated scour depths, are presented \nin tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure \n8. Scour depths were calculated assuming an infinite depth of erosive material and a \nhomogeneous particle-size distribution. \nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97393","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Striker, L.K., and Burns, R.L., 1997, Level II scour analysis for Bridge 36 (ANDOVT00110036) on VT 11, crossing Middle Branch Williams River, Andover, Vermont: U.S. Geological Survey Open-File Report 97-393, iv, 51 p., https://doi.org/10.3133/ofr97393.","productDescription":"iv, 51 p.","numberOfPages":"56","costCenters":[],"links":[{"id":169793,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97393.PNG"},{"id":279742,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0393/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Andover","otherGeospatial":"Williams River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,43.125 ], [ -72.75,43.25 ], [ -72.5,43.25 ], [ -72.5,43.125 ], [ -72.75,43.125 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b19e4b07f02db6a7f81","contributors":{"authors":[{"text":"Striker, Lora K.","contributorId":41481,"corporation":false,"usgs":true,"family":"Striker","given":"Lora","email":"","middleInitial":"K.","affiliations":[],"preferred":false,"id":240508,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Burns, Rhonda L.","contributorId":51358,"corporation":false,"usgs":true,"family":"Burns","given":"Rhonda","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":240509,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49933,"text":"ofr97378 - 1997 - Level II scour analysis for Bridge 44 (CHESVT00110044) on State Route 11, crossing Andover Brook, Chester, Vermont","interactions":[],"lastModifiedDate":"2013-12-20T11:02:16","indexId":"ofr97378","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-378","title":"Level II scour analysis for Bridge 44 (CHESVT00110044) on State Route 11, crossing Andover Brook, Chester, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nCHESVT00110044 on State Route 11 crossing Andover Brook, Chester, Vermont (figures \n1–8). A Level II study is a basic engineering analysis of the site, including a quantitative \nanalysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of \na Level I scour investigation also are included in Appendix E of this report. A Level I \ninvestigation provides a qualitative geomorphic characterization of the study site. \nInformation on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) \nfiles, was compiled prior to conducting Level I and Level II analyses and is found in \nAppendix D.
\nThe site is in the New England Upland section of the New England physiographic province \nin southeastern Vermont. The 12.6-mi2\n drainage area is in a predominantly rural and \nforested basin. In the vicinity of the study site, the surface cover is pasture with dense \nwoody vegetation on the immediate banks except the downstream left bank of the bridge \nwhich is forested.
\nIn the study area, Andover Brook has an incised, meandering channel with a slope of \napproximately 0.02 ft/ft, an average channel top width of 74 ft and an average bank height \nof 8 ft. The channel bed material ranges from gravel to boulder with a median grain size \n(D50) of 83.6 mm (0.274 ft). The geomorphic assessment at the time of the Level I and \nLevel II site visit on September 11, 1996, indicated that the reach was stable.
\nThe State Route 11 crossing of Andover Brook is a 58-ft-long, two-lane bridge consisting of \none 56-foot concrete T-beam span (Vermont Agency of Transportation, written \ncommunication, March 29, 1995). The opening length of the structure parallel to the bridge \nface is 52.9 ft.The bridge is supported by vertical, concrete abutments with wingwalls. The \nchannel is skewed approximately 35 degrees to the opening while the opening-skew-to-roadway is 45 degrees.
\nA scour hole 1.8 ft deeper than the mean thalweg depth was observed along the upstream \nleft wingwall and left abutment during the Level I assessment. The scour protection \nmeasures at the site included type-4 stone fill (less than 60 inches diameter) along the \nupstream left bank between the wingwall and a concrete wall. There was type-2 stone fill \n(less than 36 inches diameter) along the entire base of the upstream left wingwall, and the \ndownstream end of the downstream right wingwall. There was type-1 stone fill (less than \n12 inches diameter) at the downstream end of the downstream left wingwall. There was \nalso a concrete wall along the upstream left bank from 18 to 50 ft upstream of the bridge. \nAdditional details describing conditions at the site are included in the Level II Summary \nand Appendices D and E.
\nScour depths and recommended rock rip-rap sizes were computed using the general \nguidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). \nTotal scour at a highway crossing is comprised of three components: 1) long-term \nstreambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction \nin flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and \nabutments). Total scour is the sum of the three components. Equations are available to \ncompute depths for contraction and local scour and a summary of the results of these \ncomputations follows.
\nContraction scour for all modelled flows ranged from 0.0 to 1.2 ft. The worst-case \ncontraction scour occurred at the incipient-overtopping discharge. The incipientovertopping discharge is 520 cfs less than the 100-year discharge. Left abutment scour \nranged from 16.4 to 20.9 ft. The worst-case left abutment scour occurred at the 500-year \ndischarge. Right abutment scour ranged from 8.4 to 9.4 ft. The worst-case right abutment \nscour occurred at both the 100-year and 500-year discharge. Additional information on \nscour depths and depths to armoring are included in the section titled “Scour Results”. \nScoured-streambed elevations, based on the calculated scour depths, are presented in tables \n1 and 2. A cross-section of the scour computed at the bridge is presented in figure 8. Scour \ndepths were calculated assuming an infinite depth of erosive material and a homogeneous \nparticle-size distribution.
\nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.
","language":"English","publisher":"U.S. Geological Suvery","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97378","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Ivanoff, M.A., and Hammond, R.E., 1997, Level II scour analysis for Bridge 44 (CHESVT00110044) on State Route 11, crossing Andover Brook, Chester, Vermont: U.S. Geological Survey Open-File Report 97-378, iv, 51 p., https://doi.org/10.3133/ofr97378.","productDescription":"iv, 51 p.","numberOfPages":"56","costCenters":[],"links":[{"id":170528,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97378.PNG"},{"id":279749,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0378/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Chester","otherGeospatial":"Andover Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,43.25 ], [ -72.75,43.375 ], [ -72.625,43.375 ], [ -72.625,43.25 ], [ -72.75,43.25 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a61db","contributors":{"authors":[{"text":"Ivanoff, Michael A.","contributorId":27105,"corporation":false,"usgs":true,"family":"Ivanoff","given":"Michael","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":240497,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Hammond, Robert E.","contributorId":61862,"corporation":false,"usgs":true,"family":"Hammond","given":"Robert","email":"","middleInitial":"E.","affiliations":[],"preferred":false,"id":240498,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49963,"text":"ofr97592 - 1997 - Level II scour analysis for Bridge 48 (FFIETH00300048) on Town Highway 30, crossing Wanzer Brook, Fairfield, Vermont","interactions":[],"lastModifiedDate":"2013-12-18T14:02:55","indexId":"ofr97592","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-592","title":"Level II scour analysis for Bridge 48 (FFIETH00300048) on Town Highway 30, crossing Wanzer Brook, Fairfield, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nFFIETH00300048 on Town Highway 30 crossing Wanzer Brook, Fairfield, Vermont \n(figures 1–8). A Level II study is a basic engineering analysis of the site, including a \nquantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). Results of a Level I scour investigation also are included in Appendix E of this \nreport. A Level I investigation provides a qualitative geomorphic characterization of the \nstudy site. Information on the bridge, gleaned from Vermont Agency of Transportation \n(VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is \nfound in Appendix D.
\nThe site is in the Green Mountain section of the New England physiographic province in \nnorthwestern Vermont. The 6.78-mi2\n drainage area is in a predominantly rural and forested \nbasin. In the vicinity of the study site, the surface cover upstream of the bridge and on the \ndownstream right bank is primarily pasture. The downstream left bank is forested.
\nIn the study area, Wanzer Brook has an incised, straight channel with a slope of \napproximately 0.03 ft/ft, an average channel top width of 65 ft and an average bank height \nof 5 ft. The channel bed material is cobble with a median grain size (D50) of 111 mm (0.364 \nft). The geomorphic assessment at the time of the Level I and Level II site visit on July 11, \n1995, indicated that the reach was stable.
\nThe Town Highway 30 crossing of Wanzer Brook is a 31-ft-long, two-lane bridge \nconsisting of one 28-foot steel-beam span (Vermont Agency of Transportation, written \ncommunication, March 8, 1995). The opening length of the structure parallel to the bridge \nface is 26 ft.The bridge is supported by vertical stone wall abutments with concrete caps and \n“kneewall” footings. The channel is skewed approximately 25 degrees to the opening while \nthe measured opening-skew-to-roadway is 20 degrees.
\nA scour hole 1.5 ft deeper than the mean thalweg depth was observed along the downstream \nleft retaining wall (extended concrete footing) during the Level I assessment. It was also \nobserved that the right abutment is undermined with a scour depth of 0.5 ft. The scour \nprotection at the site was limited to four large boulders (type-4, less than 60 inches \ndiameter) along the downstream right retaining wall. The channel under the bridge is a \n“corduroy” log mat floor composed of 13 logs which are parallel to the bridge face and \nextend from 5 ft under the bridge to the downstream bridge face. The most downstream log \nis approximately 0.3 to 0.4 ft higher than the other logs and controls flow at lower flows. \nAdditional details describing conditions at the site are included in the Level II Summary \nand Appendices D and E.
\nScour depths and recommended rock rip-rap sizes were computed using the general \nguidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). \nTotal scour at a highway crossing is comprised of three components: 1) long-term \nstreambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction \nin flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and \nabutments). Total scour is the sum of the three components. Equations are available to \ncompute depths for contraction and local scour and a summary of the results of these \ncomputations follows.
\nContraction scour for all modelled flows ranged from 0.3 to 0.6 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour ranged from 14.1 to \n16.0 ft at the left abutment and from 6.8 to 7.6 ft at the right abutment. The worst-case \nabutment scour occurred at the 500-year discharge. Additional information on scour depths \nand 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. \nA cross-section of the scour computed at the bridge is presented in figure 8. Scour depths \nwere calculated assuming an infinite depth of erosive material and a homogeneous particle-size distribution.
\nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97592","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Flynn, R.H., and Boehmler, E.M., 1997, Level II scour analysis for Bridge 48 (FFIETH00300048) on Town Highway 30, crossing Wanzer Brook, Fairfield, Vermont: U.S. Geological Survey Open-File Report 97-592, iv, 48 p., https://doi.org/10.3133/ofr97592.","productDescription":"iv, 48 p.","numberOfPages":"53","costCenters":[],"links":[{"id":175622,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97592.GIF"},{"id":279715,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0592/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Fairfield","otherGeospatial":"Wanzer Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -73.0,44.75 ], [ -73.0,44.875 ], [ -72.875,44.875 ], [ -72.875,44.75 ], [ -73.0,44.75 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a606a","contributors":{"authors":[{"text":"Flynn, Robert H. rflynn@usgs.gov","contributorId":2137,"corporation":false,"usgs":true,"family":"Flynn","given":"Robert","email":"rflynn@usgs.gov","middleInitial":"H.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240548,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Boehmler, Erick M.","contributorId":96303,"corporation":false,"usgs":true,"family":"Boehmler","given":"Erick","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":240549,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":50010,"text":"ofr97774 - 1997 - Level II scour analysis for Bridge 29 (DORSTH00100029) on Town Highway 10, crossing the Mettawee River, Dorset, Vermont","interactions":[],"lastModifiedDate":"2016-08-25T13:29:02","indexId":"ofr97774","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-774","title":"Level II scour analysis for Bridge 29 (DORSTH00100029) on Town Highway 10, crossing the Mettawee River, Dorset, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure DORSTH00100029 on Town Highway 10 crossing the Mettawee River, Dorset, 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 Taconic section of the New England physiographic province in southwestern Vermont. The 9.5-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is forest on the upstream left overbank and the upstream and downstream right overbanks. The downstream left overbank is pasture and brushland.
In the study area, the Mettawee River has an incised, sinuous channel with a slope of approximately 0.02 ft/ft, an average channel top width of 66 ft and an average bank height of 8 ft. The channel bed material ranges from gravel to boulders with a median grain size (D50) of 79.0 mm (0.259 ft). The geomorphic assessment at the time of the Level I and Level II site visit on August 5, 1996, indicated that the reach was stable.
The Town Highway 10 crossing of the Mettawee River is a 26-ft-long, two-lane bridge consisting of a 24-ft steel-stringer span (Vermont Agency of Transportation, written communication, September 28, 1995). The opening length of the structure parallel to the bridge face is 24.1 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 45 degrees to the opening while the opening-skew-to-roadway is zero degrees.
At the upstream end of the right abutment, there is a scour hole 1.0 ft deeper than the mean thalweg depth. Scour counter-measures at the site include type-1 stone fill (less than 12 inches diameter) along the downstream right wingwall. Type-2 stone fill (less than 36 inches diameter) is present along the downstream left and right banks. Type-3 stone fill (less than 48 inches diameter) is present along the upstream left bank and sparsely in front of the right abutment. A concrete wall (old abutment) extends along 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) 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 0.4 to 1.9 ft. The worst-case contraction scour occurred at the 500-year discharge. Left abutment scour ranged from 10.5 to 10.8 ft. The worst-case left abutment scour occurred at the 500-year discharge. Right abutment scour ranged from 11.4 to 11.9 ft. The worst-case right abutment scour 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.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97774","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Wild, E.C., 1997, Level II scour analysis for Bridge 29 (DORSTH00100029) on Town Highway 10, crossing the Mettawee River, Dorset, Vermont: U.S. Geological Survey Open-File Report 97-774, iv, 51 p., https://doi.org/10.3133/ofr97774.","productDescription":"iv, 51 p.","numberOfPages":"56","costCenters":[],"links":[{"id":176808,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97774.PNG"},{"id":279669,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0774/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Dorset","otherGeospatial":"Mettawee River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,43.5 ], [ -72.75,43.625 ], [ -72.625,43.625 ], [ -72.625,43.5 ], [ -72.75,43.5 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b19e4b07f02db6a7f30","contributors":{"authors":[{"text":"Wild, Emily C. 0000-0001-6157-7629 ecwild@usgs.gov","orcid":"https://orcid.org/0000-0001-6157-7629","contributorId":1810,"corporation":false,"usgs":true,"family":"Wild","given":"Emily","email":"ecwild@usgs.gov","middleInitial":"C.","affiliations":[{"id":5081,"text":"Libraries","active":false,"usgs":true}],"preferred":false,"id":240629,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49948,"text":"ofr97405 - 1997 - Level II scour analysis for Bridge 37 (DUXBTH00120037) on Town Highway 12, crossing Ridley Brook, Duxbury, Vermont","interactions":[],"lastModifiedDate":"2016-08-25T13:32:49","indexId":"ofr97405","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-405","title":"Level II scour analysis for Bridge 37 (DUXBTH00120037) on Town Highway 12, crossing Ridley Brook, Duxbury, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure DUXBTH00120037 on Town Highway 12 crossing Ridley Brook, Duxbury, 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 10.1-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is forest upstream and downstream of the bridge.
In the study area, Ridley Brook has an incised, straight channel with a slope of approximately 0.04 ft/ft, an average channel top width of 67 ft and an average bank height of 9 ft. The channel bed material ranges from gravel to boulders with a median grain size (D50) of 123 mm (0.404 ft). The geomorphic assessment at the time of the Level I and Level II site visit on July 1, 1996, indicated that the reach was stable.
The Town Highway 12 crossing of Ridley Brook is a 33-ft-long, two-lane bridge consisting of five 30-ft steel rolled beams (Vermont Agency of Transportation, written communication, October 13, 1995). The opening length of the structure parallel to the bridge face is 30 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 50 degrees to the opening while the measured opening-skew-to-roadway is 20 degrees.
A scour hole 2 ft deeper than the mean thalweg depth was observed along the right abutment and downstream right wingwall during the Level I assessment. Scour countermeasures at the site include type-2 stone fill (less than 3 feet diameter) along the upstream and downstream left road embankments, and type-3 stone fill (less than 4 feet diameter) along the upstream right bank and 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). 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 0.6 to 1.7 ft. The worst-case contraction scour occurred at the 500-year discharge. Left abutment scour ranged from 5.0 to 8.3 ft, with the worst-case occurring at the incipient-overtopping discharge. Right abutment scour ranged from 13.1 to 16.7 ft, with the worst-case occurring 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.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97405","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Wild, E.C., and Ivanhoff, M.A., 1997, Level II scour analysis for Bridge 37 (DUXBTH00120037) on Town Highway 12, crossing Ridley Brook, Duxbury, Vermont: U.S. Geological Survey Open-File Report 97-405, iv, 52 p., https://doi.org/10.3133/ofr97405.","productDescription":"iv, 52 p.","numberOfPages":"57","costCenters":[],"links":[{"id":176359,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97405.PNG"},{"id":279735,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0405/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Duxbury","otherGeospatial":"Ridley Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,43.5 ], [ -72.75,43.625 ], [ -72.625,43.625 ], [ -72.625,43.5 ], [ -72.75,43.5 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a62ec","contributors":{"authors":[{"text":"Wild, Emily C. 0000-0001-6157-7629 ecwild@usgs.gov","orcid":"https://orcid.org/0000-0001-6157-7629","contributorId":1810,"corporation":false,"usgs":true,"family":"Wild","given":"Emily","email":"ecwild@usgs.gov","middleInitial":"C.","affiliations":[{"id":5081,"text":"Libraries","active":false,"usgs":true}],"preferred":false,"id":240521,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Ivanhoff, Michael A.","contributorId":80343,"corporation":false,"usgs":true,"family":"Ivanhoff","given":"Michael","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":240522,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49950,"text":"ofr97407 - 1997 - Level II scour analysis for Bridge 45 (NFIETH00250045) on Town Highway 25, crossing Union Brook, Northfield, Vermont","interactions":[],"lastModifiedDate":"2013-12-19T10:40:03","indexId":"ofr97407","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-407","title":"Level II scour analysis for Bridge 45 (NFIETH00250045) on Town Highway 25, crossing Union Brook, Northfield, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nNFIETH00250045 on Town Highway 25 crossing Union Brook, Northfield, Vermont \n(figures 1–8). A Level II study is a basic engineering analysis of the site, including a \nquantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). Results of a Level I scour investigation also are included in Appendix E of this \nreport. A Level I investigation provides a qualitative geomorphic characterization of the \nstudy site. Information on the bridge, gleaned from Vermont Agency of Transportation \n(VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is \nfound in Appendix D.\nThe site is in the Green Mountain section of the New England physiographic province in \ncentral Vermont. The 4.04-mi2\n drainage area is in a predominantly rural and forested basin. \nIn the vicinity of the study site, surface cover consists of shrubs and brush on all of the \nbanks except the upstream right bank which is forested.\nIn the study area, Union Brook has an incised, meandering channel with a slope of \napproximately 0.018 ft/ft, an average channel top width of 41 ft and an average bank height \nof 2 ft. The channel bed material ranges from sand to cobble with a median grain size (D50) \nof 65.8 mm (0.216 ft). The geomorphic assessment at the time of the Level I and Level II \nsite visit on July 24, 1996, indicated that the reach was unstable. The stream meanders and \nthere is a cut bank on the upstream right bank and trees are falling into the channel.\nThe Town Highway 25 crossing of Union Brook is a 28-ft-long, two-lane bridge consisting \nof one 26-foot concrete slab span (Vermont Agency of Transportation, written \ncommunication, October 13, 1995). The opening length of the structure parallel to the \nbridge face is 23.8 ft. The bridge is supported by vertical, concrete abutments with \nwingwalls. The channel is skewed approximately 50 degrees to the opening while the \nopening-skew-to-roadway is 0 degrees.\nDuring the Level I assessment, a scour hole 3.0 ft deeper than the mean thalweg depth was \nobserved at the upstream face of the bridge that extended from the center of the channel to \nthe front of the upstream left wingwall. An additional scour hole 1.5 ft deeper than the mean \nthalweg depth was observed along the downstream right bank near the bridge. The scour \ncounter measures at the site were a laid-up wall of concrete slabs along the upstream right \nbank beginning at the end of the upstream right wingwall and type-1 stone fill (less than 12 \ninches diameter) along the downstream right wingwall and bank, and type-2 stone fill (less \nthan 36 inches diameter) along the downstream left wingwall and bank. Additional details \ndescribing conditions at the site are included in the Level II Summary and Appendices D \nand E.\nScour depths and recommended rock rip-rap sizes were computed using the general \nguidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). \nTotal scour at a highway crossing is comprised of three components: 1) long-term \nstreambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction \nin flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and \nabutments). Total scour is the sum of the three components. Equations are available to \ncompute depths for contraction and local scour and a summary of the results of these \ncomputations follows.\nContraction scour for all modelled flows ranged from 0.4 to 0.9 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour ranged from 4.5 to \n9.1 ft. The worst-case abutment scour occurred at the 500-year discharge. Additional \ninformation on scour depths and depths to armoring are included in the section titled “Scour \nResults”. Scoured-streambed elevations, based on the calculated scour depths, are presented \nin tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure \n8. Scour depths were calculated assuming an infinite depth of erosive material and a \nhomogeneous particle-size distribution. \nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97407","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Burns, R.L., and Ivanoff, M.A., 1997, Level II scour analysis for Bridge 45 (NFIETH00250045) on Town Highway 25, crossing Union Brook, Northfield, Vermont: U.S. Geological Survey Open-File Report 97-407, iv, 50 p., https://doi.org/10.3133/ofr97407.","productDescription":"iv, 50 p.","numberOfPages":"55","costCenters":[],"links":[{"id":176361,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97407.PNG"},{"id":279733,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0407/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Northfield","otherGeospatial":"Union Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,44.125 ], [ -72.75,44.25 ], [ -72.625,44.25 ], [ -72.625,44.125 ], [ -72.75,44.125 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a618a","contributors":{"authors":[{"text":"Burns, Ronda L.","contributorId":71602,"corporation":false,"usgs":true,"family":"Burns","given":"Ronda","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":240526,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Ivanoff, Michael A.","contributorId":27105,"corporation":false,"usgs":true,"family":"Ivanoff","given":"Michael","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":240525,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49930,"text":"ofr97375 - 1997 - Level II scour analysis for Bridge 20 (GRAFTH00010020) on Town Highway 1, crossing the Saxtons River, Grafton Vermont","interactions":[],"lastModifiedDate":"2013-12-20T11:27:38","indexId":"ofr97375","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-375","title":"Level II scour analysis for Bridge 20 (GRAFTH00010020) on Town Highway 1, crossing the Saxtons River, Grafton Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nGRAFTH00010020 on Town Highway 1 crossing the Saxtons River, Grafton, Vermont \n(figures 1–8). A Level II study is a basic engineering analysis of the site, including a \nquantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). Results of a Level I scour investigation also are included in Appendix E of this \nreport. A Level I investigation provides a qualitative geomorphic characterization of the \nstudy site. Information on the bridge, gleaned from Vermont Agency of Transportation \n(VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is \nfound in Appendix D.
\nThe site is in the New England Upland section of the New England physiographic province \nin southeastern Vermont. The 33.9-mi2\n drainage area is in a predominantly rural and \nforested basin. In the vicinity of the study site, the surface cover is forest upstream of the \nbridge and shrub and brush downstream.
\nIn the study area, the Saxtons River has an incised, sinuous channel with a slope of \napproximately 0.01 ft/ft, an average channel top width of 97 ft and an average bank height \nof 2 ft. The predominant channel bed material is gravel with a median grain size (D50) of \n58.6 mm (0.192 ft). The geomorphic assessment at the time of the Level I and Level II site \nvisit on August 21, 1996, indicated that the reach was laterally unstable due to distinctive \ncut bank development on the upstream right bank and point bar development on the \nupstream left bank and downstream right bank.
\nThe Town Highway 1 crossing of the Saxtons River is a 191-ft-long, two-lane bridge \nconsisting of three steel-beam spans (Vermont Agency of Transportation, written \ncommunication, March 29, 1995). The bridge is supported by vertical, concrete abutments \nwith spill-through embankments and two piers. The channel is skewed approximately 40 \ndegrees to the opening. The opening-skew-to-roadway is 45 degrees in the VTAOT records \nbut measured 50 degrees from surveyed points.
\nThe scour protection measures at the site were type-1 stone fill (less than 12 inches \ndiameter) on the left abutment, type-2 stone fill (less than 36 inches diameter) on the right \nabutment and downstream right bank, and a stone wall is noted on the left bank \ndownstream. Additional details describing conditions at the site are included in the Level II \nSummary and Appendices D and E.
\nScour depths and recommended rock rip-rap sizes were computed using the general \nguidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). \nTotal scour at a highway crossing is comprised of three components: 1) long-term \nstreambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction \nin flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and \nabutments). Total scour is the sum of the three components. Equations are available to \ncompute depths for contraction and local scour and a summary of the results of these \ncomputations follows.
\nContraction scour for all modelled flows ranged from 0.0 to 0.9 feet. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour ranged from 8.0 to \n14.9 feet. The worst-case abutment scour occurred at the 500-year discharge for the right \nabutment. There are two piers for which computed pier scour ranged from 8.7 to 26.0 feet. \nThe left and right piers in this report are presented as pier 1 and pier 2 respectively. The \nworst-case pier scour occurred at pier 2 for the 500-year discharge. Additional information \non scour depths and depths to armoring are included in the section titled “Scour Results”. \nScoured-streambed elevations, based on the calculated scour depths, are presented in tables \n1 and 2. A cross-section of the scour computed at the bridge is presented in figure 8. Scour \ndepths were calculated assuming an infinite depth of erosive material and a homogeneous \nparticle-size distribution.
\nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97375","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Boehmler, E.M., and Burns, R.L., 1997, Level II scour analysis for Bridge 20 (GRAFTH00010020) on Town Highway 1, crossing the Saxtons River, Grafton Vermont: U.S. Geological Survey Open-File Report 97-375, iv, 50 p., https://doi.org/10.3133/ofr97375.","productDescription":"iv, 50 p.","numberOfPages":"55","costCenters":[],"links":[{"id":170525,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97375.PNG"},{"id":279752,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0375/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Grafton","otherGeospatial":"Saxtons River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,43.5 ], [ -72.75,43.625 ], [ -72.625,43.625 ], [ -72.625,43.5 ], [ -72.75,43.5 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b1ae4b07f02db6a835c","contributors":{"authors":[{"text":"Boehmler, Erick M.","contributorId":96303,"corporation":false,"usgs":true,"family":"Boehmler","given":"Erick","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":240493,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Burns, Ronda L.","contributorId":71602,"corporation":false,"usgs":true,"family":"Burns","given":"Ronda","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":240492,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49942,"text":"ofr97394 - 1997 - Level II scour analysis for Bridge 23 (WOLCTH00130023) on Town Highway 13, crossing the Wild Branch of the Lamoille River, Wolcott, Vermont","interactions":[],"lastModifiedDate":"2016-08-25T14:28:10","indexId":"ofr97394","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-394","title":"Level II scour analysis for Bridge 23 (WOLCTH00130023) on Town Highway 13, crossing the Wild Branch of the Lamoille River, Wolcott, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure WOLCTH00130023 on Town Highway 13 crossing the Wild Branch Lamoille River, Wolcott, 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, collected 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 northcentral Vermont. The 27.7-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is pasture on the upstream right overbank. The upstream left overbank is brushland. Downstream of the bridge, the surface cover is forested on the right overbank. The downstream left overbank is pasture while the immediate bank has dense woody vegetation.
In the study area, the Wild Branch Lamoille River has an incised, straight channel with a slope of approximately 0.009 ft/ft, an average channel top width of 65 ft and an average bank height of 7 ft. The channel bed material ranges from sand to boulders with a median grain size (D50) of 85.3 mm (0.280 ft). The geomorphic assessment at the time of the Level I and Level II site visit on July 17, 1996 indicated that the reach was laterally unstable.
The Town Highway 13 crossing of the Wild Branch Lamoille River is a 41-ft-long, one-lane bridge consisting of a 39-foot steel girder span (Vermont Agency of Transportation, written communication, October 13, 1995). The opening length of the structure parallel to the bridge face is 38 ft. The bridge is supported by vertical, concrete abutments. The right abutment has concrete wingwalls. The channel is skewed approximately 45 degrees to the opening while the opening-skew-to-roadway is zero degrees.
A scour hole 3.5 ft deeper than the mean thalweg depth was observed in the channel during the Level I assessment. Scour countermeasures at the site includes type-2 stone fill (less than 3 feet diameter) along the banks, the right wingwalls, the right abutment and the road embankments. 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 1.0 to 2.1 ft. The worst-case contraction scour occurred at the 100-year discharge. Left abutment scour ranged from 9.1 to 13.2 ft. Right abutment scour ranged from 15.7 to 22.3 ft. The worst-case abutment scour occurred at the 500- year discharge for both abutments. 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.
During the August 1995 flood, the Wild Branch Lamoille River overtopped the bridge deck at structure WOLCTH00130023. Debris also was caught in the upstream I-beam of the structure.
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.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97394","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Wild, E.C., and Degnan, J.R., 1997, Level II scour analysis for Bridge 23 (WOLCTH00130023) on Town Highway 13, crossing the Wild Branch of the Lamoille River, Wolcott, Vermont: U.S. Geological Survey Open-File Report 97-394, iv, 51 p., https://doi.org/10.3133/ofr97394.","productDescription":"iv, 51 p.","numberOfPages":"56","costCenters":[],"links":[{"id":169794,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97394.PNG"},{"id":279741,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0394/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Wolcott","otherGeospatial":"Lamoille River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,43.5 ], [ -72.75,43.625 ], [ -72.625,43.625 ], [ -72.625,43.5 ], [ -72.75,43.5 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b1ae4b07f02db6a809e","contributors":{"authors":[{"text":"Wild, Emily C. 0000-0001-6157-7629 ecwild@usgs.gov","orcid":"https://orcid.org/0000-0001-6157-7629","contributorId":1810,"corporation":false,"usgs":true,"family":"Wild","given":"Emily","email":"ecwild@usgs.gov","middleInitial":"C.","affiliations":[{"id":5081,"text":"Libraries","active":false,"usgs":true}],"preferred":false,"id":240511,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Degnan, James R. 0000-0002-5665-9010 jrdegnan@usgs.gov","orcid":"https://orcid.org/0000-0002-5665-9010","contributorId":498,"corporation":false,"usgs":true,"family":"Degnan","given":"James","email":"jrdegnan@usgs.gov","middleInitial":"R.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true},{"id":466,"text":"New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240510,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49949,"text":"ofr97406 - 1997 - Level II scour analysis for Bridge 29 (PUTNTH00210029) on Town Highway 21, crossing East Putney Brook, Putney, Vermont","interactions":[],"lastModifiedDate":"2013-12-19T10:52:24","indexId":"ofr97406","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-406","title":"Level II scour analysis for Bridge 29 (PUTNTH00210029) on Town Highway 21, crossing East Putney Brook, Putney, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nPUTNTH00210029 on Town Highway 21 crossing East Putney Brook, Putney, Vermont \n(figures 1–8). A Level II study is a basic engineering analysis of the site, including a \nquantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). Results of a Level I scour investigation also are included in Appendix E of this \nreport. A Level I investigation provides a qualitative geomorphic characterization of the \nstudy site. Information on the bridge, gleaned from Vermont Agency of Transportation \n(VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is \nfound in Appendix D.\nThe site is in the New England Upland section of the New England physiographic province \nin southeastern Vermont. The 10.3-mi2\n drainage area is in a predominantly rural and \nforested basin. In the vicinity of the study site, the surface cover consists of pasture and \nforest.\nIn the study area, East Putney Brook has an incised, sinuous channel with a slope of \napproximately 0.009 ft/ft, an average channel top width of 33 ft and an average bank height \n(channel depth) of 3 ft. The channel bed material is cobbles predominantly with a median \ngrain size (D50) of 80.7 mm (0.265 ft). The geomorphic assessment at the time of the Level \nI and Level II site visit on August 19, 1996, indicated that the reach was stable.\nThe Town Highway 21 crossing of East Putney Brook is a 35-ft-long, one-lane bridge \nconsisting of one 29-foot steel-beam span (Vermont Agency of Transportation, written \ncommunication, March 30, 1995). The bridge is supported by vertical, concrete abutments \nwith wingwalls. The channel is skewed approximately 40 degrees to the opening. Historical \nrecords show an opening-skew-to-roadway of 10 degrees but 20 degrees was computed \nusing field survey data and used in this study.\nThe scour protection measures at the site were type-2 stone fill (less than 36 inches \ndiameter) on each abutment wall, the upstream right wingwall and the upstream right bank, \nand type-3 stone fill (less than 48 inches diameter) on the left bank upstream, the upstream \nleft wingwall, and the downstream right bank. Additional details describing conditions at \nthe site are included in the Level II Summary and Appendices D and E.\nScour depths and recommended rock rip-rap sizes were computed using the general \nguidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). \nTotal scour at a highway crossing is comprised of three components: 1) long-term \nstreambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction \nin flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and \nabutments). Total scour is the sum of the three components. Equations are available to \ncompute depths for contraction and local scour and a summary of the results of these \ncomputations follows.\nContraction scour for all modelled flows ranged from 0.0 to 0.9 feet. The worst-case \ncontraction scour occurred at the incipient-overtopping discharge, which was less than the \n100-year discharge. Abutment scour ranged from 6.1 to 18.4 feet. The worst-case abutment \nscour occurred at the 500-year discharge for the right abutment and the incipient \novertopping discharge for the left abutment. Additional information on scour depths and \ndepths to armoring are included in the section titled “Scour Results”. Scoured-streambed \nelevations, based on the calculated scour depths, are presented in tables 1 and 2. A crosssection of the scour computed at the bridge is presented in figure 8. Scour depths were \ncalculated assuming an infinite depth of erosive material and a homogeneous particle-size \ndistribution. \nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97406","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Boehmler, E.M., and Ivanoff, M.A., 1997, Level II scour analysis for Bridge 29 (PUTNTH00210029) on Town Highway 21, crossing East Putney Brook, Putney, Vermont: U.S. Geological Survey Open-File Report 97-406, iv, 50 p., https://doi.org/10.3133/ofr97406.","productDescription":"iv, 50 p.","numberOfPages":"55","costCenters":[],"links":[{"id":176360,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97406.PNG"},{"id":279734,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0406/report.pdf"}],"scale":"25000","country":"United States","state":"Vermont","city":"Putney","otherGeospatial":"Putney Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,42.5 ], [ -72.75,43.125 ], [ -72.0,43.125 ], [ -72.0,42.5 ], [ -72.75,42.5 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b19e4b07f02db6a7f25","contributors":{"authors":[{"text":"Boehmler, Erick M.","contributorId":96303,"corporation":false,"usgs":true,"family":"Boehmler","given":"Erick","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":240524,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Ivanoff, Michael A.","contributorId":27105,"corporation":false,"usgs":true,"family":"Ivanoff","given":"Michael","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":240523,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49945,"text":"ofr97397 - 1997 - Level II scour analysis for Bridge 6 (ALBUTH00150006) on Town Highway 15, crossing Mud Creek, Alburg, Vermont","interactions":[],"lastModifiedDate":"2013-12-19T12:59:01","indexId":"ofr97397","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-397","title":"Level II scour analysis for Bridge 6 (ALBUTH00150006) on Town Highway 15, crossing Mud Creek, Alburg, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nALBUTH00150006 on Town Highway 15 crossing Mud Creek, Alburg, Vermont (figures \n1–8). A Level II study is a basic engineering analysis of the site, including a quantitative \nanalysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of \na Level I scour investigation also are included in Appendix E of this report. A Level I \ninvestigation provides a qualitative geomorphic characterization of the study site. \nInformation on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) \nfiles, was compiled prior to conducting Level I and Level II analyses and is found in \nAppendix D.\nThe site is in the Champlain section of the St. Lawrence Valley physiographic province in \nnorthwestern Vermont. The 2.90-mi2\n drainage area is in a predominantly rural and forested \nbasin. However, nearly a third of the drainage, including the location of the study site, is \nwetland.\nIn the study area, Mud Creek has an sinuous channel through wetland with a slope of \napproximately 0.0002 ft/ft, an average channel top width of 42 ft and an average bank \nheight of 2 ft. The channel bed material ranges from clay to sand with an estimated median \ngrain size (D50) of 0.047 mm (0.00015 ft). The geomorphic assessment at the time of the \nLevel I and Level II site visit on June 26, 1995, indicated that the reach was stable.\nThe Town Highway 15 crossing of Mud Creek is a 30-ft-long, one-lane bridge consisting of \none 28-foot steel-beam span (Vermont Agency of Transportation, written communication, \nMarch 7, 1995). The opening length of the structure parallel to the bridge face is 26.7 ft. \nThe bridge is supported by vertical, concrete abutments with wingwalls. The channel is \nskewed zero degrees to the opening and the opening-skew-to-roadway is also zero degrees. \nChannel scour, approximately 2 ft deeper than the mean thalweg depth, was observed in the \nmiddle of the channel extending from 5 to 35 ft upstream of the bridge. The only scour \ncountermeasure observed at this site was some small stone, possibly type-1 stone fill (less \nthan 12 inches diameter), partially covering the channel bed under the bridge. Additional \ndetails describing conditions at the site are included in the Level II Summary and \nAppendices D and E.\nScour depths and recommended rock rip-rap sizes were computed using the general \nguidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). \nTotal scour at a highway crossing is comprised of three components: 1) long-term \nstreambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction \nin flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and \nabutments). Total scour is the sum of the three components. Equations are available to \ncompute depths for contraction and local scour and a summary of the results of these \ncomputations follows.\nContraction scour for all modelled flows ranged from 6.2 to 7.2 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour ranged from 2.0 to \n2.4 ft and 2.1 to 2.6 ft on the left and right abutments respectively. The worst-case abutment \nscour occurred at the 500-year discharge. Additional information on scour depths and \ndepths to armoring are included in the section titled “Scour Results”. Scoured-streambed \nelevations, based on the calculated scour depths, are presented in tables 1 and 2. A crosssection of the scour computed at the bridge is presented in figure 8. Scour depths were \ncalculated assuming an infinite depth of erosive material and a homogeneous particle-size \ndistribution.\nUsually, computed scour depths are evaluated in combination with other information \nincluding (but not limited to) historical performance during flood events, the geomorphic \nstability assessment, existing scour protection measures, and the results of the hydraulic \nanalyses. Therefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97397","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Olson, S.A., 1997, Level II scour analysis for Bridge 6 (ALBUTH00150006) on Town Highway 15, crossing Mud Creek, Alburg, Vermont: U.S. Geological Survey Open-File Report 97-397, iv, 50 p., https://doi.org/10.3133/ofr97397.","productDescription":"iv, 50 p.","numberOfPages":"55","costCenters":[],"links":[{"id":169878,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97397.PNG"},{"id":279738,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0397/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Alburg","otherGeospatial":"Mud Creek","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -73.375,44.875 ], [ -73.375,45.0 ], [ -73.25,45.0 ], [ -73.25,44.875 ], [ -73.375,44.875 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b16e4b07f02db6a55c6","contributors":{"authors":[{"text":"Olson, Scott A. 0000-0002-1064-2125 solson@usgs.gov","orcid":"https://orcid.org/0000-0002-1064-2125","contributorId":2059,"corporation":false,"usgs":true,"family":"Olson","given":"Scott","email":"solson@usgs.gov","middleInitial":"A.","affiliations":[{"id":405,"text":"NH/VT office of New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":240516,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49928,"text":"ofr97373 - 1997 - Level II scour analysis for Bridge 39 (ANDOVT00110039) on State Route 11, crossing the Middle Branch Williams River, Andover, Vermont","interactions":[],"lastModifiedDate":"2013-12-20T11:42:05","indexId":"ofr97373","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-373","title":"Level II scour analysis for Bridge 39 (ANDOVT00110039) on State Route 11, crossing the Middle Branch Williams River, Andover, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nANDOVT00110039 on State Route 11 crossing the Middle Branch Williams River, \nAndover, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, \nincluding a quantitative analysis of stream stability and scour (U.S. Department of \nTransportation, 1993). Results of a Level I scour investigation also are included in \nAppendix E of this report. A Level I investigation provides a qualitative geomorphic \ncharacterization of the study site. Information on the bridge, gleaned from Vermont Agency \nof Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II \nanalyses and is found in Appendix D.
\nThe site is in the Green Mountain section of the New England physiographic province in \nsouthern Vermont. The 5.75-mi2\n drainage area is in a predominantly rural and forested \nbasin. In the vicinity of the study site, the surface cover is forest on the upstream left bank \nand downstream right bank. The surface cover on the upstream right and downstream left \nbanks is brush.
\nIn the study area, the Middle Branch Williams River has an incised, sinuous channel with a \nslope of approximately 0.01 ft/ft, an average channel top width of 58 ft and an average bank \nheight of 8 ft. The channel bed material ranges from sand to boulder with a median grain \nsize (D50) of 96.8 mm (0.317 ft). The geomorphic assessment at the time of the Level I and \nLevel II site visit on September 9, 1996, indicated that the reach was laterally unstable.
\nThe State Route 11 crossing of the Middle Branch Williams River is a 43-ft-long, two-lane \nbridge consisting of one 41-foot concrete-beam span and two additional steel beams on the \nupstream face (Vermont Agency of Transportation, written communication, March 29, \n1995). The bridge is supported by vertical, concrete abutments with wingwalls. The channel \nis skewed approximately 45 degrees to the opening while the opening-skew-to-roadway is \n45 degrees.
\nThe only scour protection measures at the site was type-2 stone fill (less than 36 inches \ndiameter) at the upstream end of the upstream right wingwall and type-3 stone fill (less than \n48 inches diameter) along the entire base length of the upstream left wingwall. Additional \ndetails describing conditions at the site are included in the Level II Summary and \nAppendices D and E.
\nScour depths and recommended rock rip-rap sizes were computed using the general \nguidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). \nTotal scour at a highway crossing is comprised of three components: 1) long-term \nstreambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction \nin flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and \nabutments). Total scour is the sum of the three components. Equations are available to \ncompute depths for contraction and local scour and a summary of the results of these \ncomputations follows.
\nContraction scour for all modelled flows ranged from 0.0 to 0.8 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour ranged from 8.9 to \n11.2 ft. The worst-case abutment scour occurred at the incipient-overtopping discharge. \nAdditional information on scour depths and depths to armoring are included in the section \ntitled “Scour Results”. Scoured-streambed elevations, based on the calculated scour depths, \nare presented in tables 1 and 2. A cross-section of the scour computed at the bridge is \npresented in figure 8. Scour depths were calculated assuming an infinite depth of erosive \nmaterial and a homogeneous particle-size distribution.
\nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97373","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Burns, R.L., and Wild, E.C., 1997, Level II scour analysis for Bridge 39 (ANDOVT00110039) on State Route 11, crossing the Middle Branch Williams River, Andover, Vermont: U.S. Geological Survey Open-File Report 97-373, iv, 52 p., https://doi.org/10.3133/ofr97373.","productDescription":"iv, 52 p.","numberOfPages":"57","costCenters":[],"links":[{"id":170523,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97373.PNG"},{"id":279754,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0373/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Andover","otherGeospatial":"Middle Branch Williams River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,43.25 ], [ -72.75,43.375 ], [ -72.625,43.375 ], [ -72.625,43.25 ], [ -72.75,43.25 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a6544","contributors":{"authors":[{"text":"Burns, Ronda L.","contributorId":71602,"corporation":false,"usgs":true,"family":"Burns","given":"Ronda","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":240489,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Wild, Emily C. 0000-0001-6157-7629 ecwild@usgs.gov","orcid":"https://orcid.org/0000-0001-6157-7629","contributorId":1810,"corporation":false,"usgs":true,"family":"Wild","given":"Emily","email":"ecwild@usgs.gov","middleInitial":"C.","affiliations":[{"id":5081,"text":"Libraries","active":false,"usgs":true}],"preferred":false,"id":240488,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49958,"text":"ofr97579 - 1997 - Level II scour analysis for Bridge 26 (ROYATH00540026) on Town Highway 54, crossing Broad Brook, Royalton, Vermont","interactions":[],"lastModifiedDate":"2013-12-18T15:12:10","indexId":"ofr97579","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"97-579","title":"Level II scour analysis for Bridge 26 (ROYATH00540026) on Town Highway 54, crossing Broad Brook, Royalton, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nROYATH00540026 on Town Highway 54 crossing Broad Brook, Royalton, Vermont \n(figures 1–8). A Level II study is a basic engineering analysis of the site, including a \nquantitative analysis of stream stability and scour (U.S. Department of Transportation, \n1993). Results of a Level I scour investigation also are included in Appendix E of this \nreport. A Level I investigation provides a qualitative geomorphic characterization of the \nstudy site. Information on the bridge, gleaned from Vermont Agency of Transportation \n(VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is \nfound in Appendix D.
\nThe site is in the New England Upland section of the New England physiographic province \nin central Vermont. The 11.9-mi2\n drainage area is in a predominantly rural and forested \nbasin. In the vicinity of the study site, the surface cover on the left bank upstream and \ndownstream is pasture with trees and brush on the immediate banks. The right bank, \nupstream and downstream of the bridge, is forested.
\nIn the study area, Broad Brook has an incised, sinuous channel with a slope of \napproximately 0.01 ft/ft, an average channel top width of 37 ft and an average bank height \nof 4 ft. The channel bed material ranges from sand to boulders with a median grain size \n(D50) of 66.3 mm (0.218 ft). The geomorphic assessment at the time of the Level I site visit \non April 13, 1995 and the Level II site visit on July 11, 1996, indicated that the reach was \nstable.
\nThe Town Highway 54 crossing of Broad Brook is a 29-ft-long, one-lane bridge consisting \nof one 24-foot steel-beam span with a timber deck (Vermont Agency of Transportation, \nwritten communication, March 23, 1995). The opening length of the structure parallel to the \nbridge face is 23.3 ft. The bridge is supported by a vertical, concrete face laid-up stone \nabutment with concrete wingwalls on the left and a laid-up stone abutment on the right. The \nchannel is skewed approximately 20 degrees to the opening while the opening-skew-to-roadway is zero degrees.
\nA scour hole 1.0 ft deeper than the mean thalweg depth was observed along the downstream \nend of the right abutment during the Level I assessment. Also, at the upstream end of the \nleft abutment, the footing is exposed 0.5 ft. The scour protection measures at the site \nincluded type-2 stone fill (less than 36 inches diameter) along the upstream left bank, at the \nupstream end of the upstream left wingwall, along the entire length of the downstream left \nwingwall, and at the upstream end of the right abutment. Additional details describing \nconditions at the site are included in the Level II Summary and Appendices D and E.
\nScour depths and recommended rock rip-rap sizes were computed using the general \nguidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995). \nTotal scour at a highway crossing is comprised of three components: 1) long-term \nstreambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction \nin flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and \nabutments). Total scour is the sum of the three components. Equations are available to \ncompute depths for contraction and local scour and a summary of the results of these \ncomputations follows.
\nContraction scour for all modelled flows ranged from 0.0 to 1.4 ft. The worst-case \ncontraction scour occurred at the incipient roadway-overtopping discharge, which was less \nthan the 100-year discharge. Abutment scour ranged from 2.2 to 7.4 ft on the left and from \n14.7 to 17.7 ft on the right. The worst-case abutment scour occurred at the incipient \nroadway-overtopping discharge for the left and at the 500-year discharge for the right. \nAdditional information on scour depths and depths to armoring are included in the section \ntitled “Scour Results”. Scoured-streambed elevations, based on the calculated scour depths, \nare presented in tables 1 and 2. A cross-section of the scour computed at the bridge is \npresented in figure 8. Scour depths were calculated assuming an infinite depth of erosive \nmaterial and a homogeneous particle-size distribution.
\nIt is generally accepted that the Froehlich equation (abutment scour) gives “excessively \nconservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, \ncomputed scour depths are evaluated in combination with other information including (but \nnot limited to) historical performance during flood events, the geomorphic stability \nassessment, existing scour protection measures, and the results of the hydraulic analyses. \nTherefore, scour depths adopted by VTAOT may differ from the computed values \ndocumented herein.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Pembroke, NH","doi":"10.3133/ofr97579","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Burns, R.L., and Weber, M.A., 1997, Level II scour analysis for Bridge 26 (ROYATH00540026) on Town Highway 54, crossing Broad Brook, Royalton, Vermont: U.S. Geological Survey Open-File Report 97-579, iv, 51 p., https://doi.org/10.3133/ofr97579.","productDescription":"iv, 51 p.","numberOfPages":"56","costCenters":[],"links":[{"id":175617,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97579.GIF"},{"id":279721,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0579/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Royalton","otherGeospatial":"Broad Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.625,43.75 ], [ -72.625,43.875 ], [ -72.5,43.875 ], [ -72.5,43.75 ], [ -72.625,43.75 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b1ae4b07f02db6a7fed","contributors":{"authors":[{"text":"Burns, Ronda L.","contributorId":71602,"corporation":false,"usgs":true,"family":"Burns","given":"Ronda","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":240540,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Weber, Matthew A.","contributorId":41483,"corporation":false,"usgs":true,"family":"Weber","given":"Matthew","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":240539,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":53933,"text":"itr19970005 - 1997 - Selected habitat suitability index model evaluations","interactions":[],"lastModifiedDate":"2018-10-25T18:26:42","indexId":"itr19970005","displayToPublicDate":"1994-01-01T00:00:00","publicationYear":"1997","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":1,"text":"Federal Government Series"},"seriesTitle":{"id":37,"text":"Information and Technology Report","active":false,"publicationSubtype":{"id":1}},"seriesNumber":"1997-0005","title":"Selected habitat suitability index model evaluations","docAbstract":"No abstract available.