This report provides the results of a detailed Level II analysis of scour potential at structure \nNEWFVT00300013 on State Route 30 crossing Smith Brook, Newfane, 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 9.38-mi2\n drainage area is in a predominantly rural and \nforested basin. In the vicinity of the study site, the surface cover is grass and shrubs except \nfor the upstream right bank which is forested.
\nIn the study area, Smith Brook has an incised, sinuous channel with a slope of \napproximately 0.01 ft/ft, an average channel top width of 53 ft and an average bank height \nof 5 ft. The channel bed material is predominantly cobbles with a median grain size (D50) of \n79.5 mm (0.261 ft). The geomorphic assessment at the time of the Level I and Level II site \nvisit on August 20, 1996, indicated that the reach was stable.
\nThe State Route 30 crossing of Smith Brook is a 69-ft-long, two-lane bridge consisting of \none 66-foot steel-beam span (Vermont Agency of Transportation, written communication, \nMarch 30, 1995). The bridge is supported by vertical, concrete abutments with wingwalls. \nThe channel is skewed approximately 45 degrees to the opening while the opening-skew-to-\nroadway is 55 degrees.
\nThe scour protection measures at the site were type-1 stone fill (less than 12 inches \ndiameter) along the upstream right bank. There was also type-2 stone fill (less than 36 \ninches diameter) along the upstream left bank. A stone wall extends to 72 feet upstream \nfrom the end of the upstream left wingwall. There is another stone wall along the upstream \nright bank. 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 0.8 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour ranged from 14.4 to \n18.2 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/ofr97218","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Ivanoff, M.A., and Medalie, L., 1997, Level II scour analysis for Bridge 30 (NEWFVT00300013) on Vermont Highway 30, crossing Smith Brook, Newfane, Vermont: U.S. Geological Survey Open-File Report 97-218, iv, 48 p., https://doi.org/10.3133/ofr97218.","productDescription":"iv, 48 p.","numberOfPages":"53","costCenters":[],"links":[{"id":169645,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97218.GIF"},{"id":279778,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0218/report.pdf"}],"scale":"25000","country":"United States","state":"Vermont","city":"Newfane","otherGeospatial":"Smith Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,42.875 ], [ -72.75,43.0 ], [ -72.5,43.0 ], [ -72.5,42.875 ], [ -72.75,42.875 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b19e4b07f02db6a7eb9","contributors":{"authors":[{"text":"Ivanoff, Michael A.","contributorId":27105,"corporation":false,"usgs":true,"family":"Ivanoff","given":"Michael","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":240458,"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":240457,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49908,"text":"ofr97225 - 1997 - Level II scour analysis for Bridge 27 (ANDOTH00290027) on Town Highway 29, crossing Middle Branch Williams River, Andover, Vermont","interactions":[],"lastModifiedDate":"2014-01-05T13:56:45","indexId":"ofr97225","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":"97-225","title":"Level II scour analysis for Bridge 27 (ANDOTH00290027) on Town Highway 29, crossing Middle Branch Williams River, Andover, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nANDOTH00290027 on Town Highway 29 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 \ncentral Vermont. The 12.7-mi2\n drainage area is in a predominantly rural and forested basin. \nIn the vicinity of the study site, the surface cover is pasture on the left bank upstream of the \nbridge while the immediate bank has woody vegetation. The surface cover on the upstream \nright bank is forest. Downstream of the bridge the left bank is pasture and the right bank \nhas woody vegetation.
\nIn the study area, the Middle Branch Williams River has an incised, straight channel with a \nslope of approximately 0.009 ft/ft, an average channel top width of 63 ft and an average \nbank height of 5 ft. The channel bed material ranges from sand to cobble with a median \ngrain size (D50) of 64.7 mm (0.212 ft). The geomorphic assessment at the time of the Level \nI and Level II site visit on September 10, 1996, indicated that the reach was stable.
\nThe Town Highway 29 crossing of the Middle Branch Williams River is a 34-ft-long, two-\nlane bridge consisting of one 32-foot steel-beam span (Vermont Agency of Transportation, \nwritten communication, April 5, 1995). The bridge is supported by vertical, concrete \nabutments with wingwalls. The channel is skewed approximately 25 degrees to the opening \nwhile the opening-skew-to-roadway is 0 degrees.
\nA scour hole 1.5 ft deeper than the mean thalweg depth was observed along the left \nabutment during the Level I assessment. Scour protection measures at the site include type-\n2 stone fill (less than 36 inches diameter) along the upstream right bank and downstream \nleft bank and around the upstream left and right wingwalls. Type- 3 stone fill (less than 48 \ninches diameter) is located along the base of the left abutment in the scour hole, at the end \nof the downstream left wingwall and along the upstream left 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 incipient-overtopping discharge and the 100-year \ndischarge. Abutment scour ranged from 10.7 to 13.6 ft. The worst-case abutment scour \noccurred at the 500-year discharge. Additional information on scour depths and depths to \narmoring are included in the section titled “Scour Results”. Scoured-streambed elevations, \nbased on the calculated scour depths, are presented in tables 1 and 2. A cross-section of the \nscour computed at the bridge is presented in figure 8. Scour depths were calculated \nassuming 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/ofr97225","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 27 (ANDOTH00290027) on Town Highway 29, crossing Middle Branch Williams River, Andover, Vermont: U.S. Geological Survey Open-File Report 97-225, iv, 50 p., https://doi.org/10.3133/ofr97225.","productDescription":"iv, 50 p.","numberOfPages":"55","costCenters":[],"links":[{"id":169646,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97225.GIF"},{"id":279775,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0225/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":"4f4e4b1ae4b07f02db6a7ffe","contributors":{"authors":[{"text":"Burns, Ronda L.","contributorId":71602,"corporation":false,"usgs":true,"family":"Burns","given":"Ronda","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":240460,"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":240459,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49909,"text":"ofr97226 - 1997 - Level II scour analysis for Bridge 12 (HUNTTH00010012) on Town Highway 001, crossing Brush Brook, Huntington, Vermont","interactions":[],"lastModifiedDate":"2014-01-06T11:07:06","indexId":"ofr97226","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":"97-226","title":"Level II scour analysis for Bridge 12 (HUNTTH00010012) on Town Highway 001, crossing Brush Brook, Huntington, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nHUNTTH00010012 on Town Highway 1 crossing Brush Brook, Huntington, Vermont \n(figures 1–9). 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.
\nIn August 1976, Hurricane Belle caused flooding at this site which resulted in road and \nbridge damage (figures 7-8). This was approximately a 25-year flood event based on flood-\nfrequency data contained in the Flood Insurance Study for the Town of Huntington (U.S. \nDepartment of Housing and Urban Development, 1978).
\nThe site is in the Green Mountain section of the New England physiographic province in \ncentral Vermont. The 9.19-mi2\n drainage area is in a predominantly rural and forested basin. \nIn the vicinity of the study site, the surface cover is pasture while the immediate banks have \nsome woody vegetation.
\nIn the study area, the Brush Brook has a sinuous channel with a slope of approximately 0.02 \nft/ft, an average channel top width of 62 ft and an average bank height of 5 ft. The channel \nbed material ranges from gravel to cobble with a median grain size (D50) of 100.0 mm \n(0.328 ft). The geomorphic assessment at the time of the Level I and Level II site visit on \nJune 25, 1996, indicated that the reach was stable.
\nThe Town Highway 1 crossing of Brush Brook is a 64-ft-long, two-lane bridge consisting of \none 62-foot steel-stringer span (Vermont Agency of Transportation, written \ncommunication, November 30, 1995). The bridge is supported by vertical, concrete \nabutments with wingwalls. The channel is skewed approximately 10 degrees to the opening \nwhile the opening-skew-to-roadway is 6 degrees.
\nChannel scour 2.2 ft deeper than the mean thalweg depth was observed along the upstream \nright bank and along the base of the spill-through protection for the right abutment during \nthe Level I assessment. Scour protection measured at the site was type-2 stone fill (less \nthan 36 inches diameter) along the upstream left and right banks and in front of all four \nwingwalls. In front of the abutments, there was type-3 stone fill (less than 48 inches \ndiameter) forming a spill-through slope. 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.
\nThere was no computed contraction scour for any modelled flow. Abutment scour ranged \nfrom 1.4 to 2.8 ft. The worst-case abutment scour occurred at the 500-year 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 9. 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/ofr97226","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 12 (HUNTTH00010012) on Town Highway 001, crossing Brush Brook, Huntington, Vermont: U.S. Geological Survey Open-File Report 97-226, iv, 49 p., https://doi.org/10.3133/ofr97226.","productDescription":"iv, 49 p.","numberOfPages":"54","costCenters":[],"links":[{"id":169718,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97226.GIF"},{"id":279777,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0226/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Huntington","otherGeospatial":"Brush Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -73.0,44.25 ], [ -73.0,44.375 ], [ -72.875,44.375 ], [ -72.875,44.25 ], [ -73.0,44.25 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b1ae4b07f02db6a83b3","contributors":{"authors":[{"text":"Burns, Ronda L.","contributorId":71602,"corporation":false,"usgs":true,"family":"Burns","given":"Ronda","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":240462,"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":240461,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49910,"text":"ofr97227 - 1997 - Level II scour analysis for Bridge 43 (SPRICYBRIG0043) on Bridge Street, crossing the Black River, Springfield, Vermont","interactions":[],"lastModifiedDate":"2014-01-06T09:32:01","indexId":"ofr97227","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":"97-227","title":"Level II scour analysis for Bridge 43 (SPRICYBRIG0043) on Bridge Street, crossing the Black River, Springfield, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nSPRICYBRIG0043 on Bridge Street crossing the Black River, Springfield, 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 191-mi2\n drainage area is a predominantly rural and forested \nbasin. In the vicinity of the study site, the surface cover consist of some grass, buildings, \nand pavement. The immediate banks are covered with trees, shrubs and brush.
\nIn the study area, the Black River has an incised channel with a slope of approximately \n0.001 ft/ft, an average channel top width of 156 ft and an average bank height of 14 ft. The \nchannel bed material is predominantly cobbles with a median grain size (D50) of 90.7 mm \n(0.298 ft). The geomorphic assessment at the time of the Level I and Level II site visit on \nSeptember 19, 1996, indicated that the reach was stable.
\nThe Bridge Street crossing of the Black River is a 123-foot-long, two-lane bridge consisting \nof one 119-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 20 degrees to the opening while the \nopening-skew-to-roadway is 20 degrees.
\nThe scour protection measures at the site were type-2 stone fill (less than 36 inches \ndiameter) along the downstream left bank and the downstream left wingwall. There was \nalso type-1 stone fill (less than 12 inches diameter) along right abutment and the \ndownstream right wingwall. There is a nine foot tall concrete wall along the downstream \nright bank to 89 feet downstream of the bridge. 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.
\nThere was no computed contraction scour. Left abutment scour ranged from 9.9 to 11 ft. \nThe worst-case left abutment scour occurred at the 100-year discharge. Right abutment \nscour ranged from 6.5 to 11.2 ft. The worst-case right abutment scour occurred at the 500-\nyear discharge. Additional information on scour depths and depths to armoring are \nincluded in the section titled “Scour Results”. Scoured-streambed elevations, based on the \ncalculated scour depths, are presented in tables 1 and 2. A cross-section of the scour \ncomputed at the bridge is presented in figure 8. Scour depths were calculated assuming an \ninfinite 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/ofr97227","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Ivanoff, M.A., and Medalie, L., 1997, Level II scour analysis for Bridge 43 (SPRICYBRIG0043) on Bridge Street, crossing the Black River, Springfield, Vermont: U.S. Geological Survey Open-File Report 97-227, iv, 48 p., https://doi.org/10.3133/ofr97227.","productDescription":"iv, 48 p.","numberOfPages":"53","costCenters":[],"links":[{"id":169719,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97227.GIF"},{"id":279776,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0227/report.pdf"}],"scale":"25000","country":"United States","state":"Vermont","city":"Springfield","otherGeospatial":"Black River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.5,43.25 ], [ -72.5,43.375 ], [ -72.25,43.375 ], [ -72.25,43.25 ], [ -72.5,43.25 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a61c3","contributors":{"authors":[{"text":"Ivanoff, Michael A.","contributorId":27105,"corporation":false,"usgs":true,"family":"Ivanoff","given":"Michael","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":240464,"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":240463,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49914,"text":"ofr97342 - 1997 - Level II scour analysis for Bridge 43 (CHESVT00110043) on State Highway 11, crossing the Middle Branch Williams River, Chester, Vermont","interactions":[],"lastModifiedDate":"2014-01-05T13:14:13","indexId":"ofr97342","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":"97-342","title":"Level II scour analysis for Bridge 43 (CHESVT00110043) on State Highway 11, crossing the Middle Branch Williams River, Chester, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nCHESVT00110043 on State Route 11 crossing the Middle Branch of the Williams River, \nChester, 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 principally in the Green Mountain section of the New England physiographic \nprovince in southeastern Vermont. The 13.7-mi2\n drainage area is in a predominantly rural \nand forested basin. In the vicinity of the study site, the surface cover is predominantly forest \nexcept for the area downstream and right of the bridge which is pasture.
\nIn the study area, the Middle Branch of the Williams River has a sinuous channel with a \nslope of approximately 0.01 ft/ft, an average channel top width of 77 ft and an average bank \nheight of 8 ft. The channel bed material ranges from gravel to boulder with a median grain \nsize (D50) of 76.6 mm (0.251 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 laterally unstable. \nLateral instability was evident from the several point bars and cut banks located through the \nstudy reach.
\nThe State Route 11 crossing of the Middle Branch of the Williams River is a\n76-ft-long, two-lane bridge consisting of two 37-foot concrete Tee-beam spans (Vermont \nAgency of Transportation, written communication, March 29, 1995). The bridge is \nsupported by vertical, concrete abutments with wingwalls. The channel is skewed \napproximately 35 degrees to the opening. The computed opening-skew-to-roadway was 30 \ndegrees but the historical records indicate this angle is 25 degrees.
\nScour protection measures at the site consist of type-1 stone fill (less than 12 inches \ndiameter) along the downstream banks and the upstream right wing wall. Type-2 (less than \n36 inches diameter) stone fill protection is noted on the upstream and downstream left \nwingwalls and upstream along the left bank. Additional details describing conditions at the \nsite 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 1.5 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour ranged from 7.2 to \n10.7 ft. The worst-case abutment scour occurred at the 500-year discharge for the right \nabutment. Pier scour ranged from 7.3 to 8.6 ft. The worst-case pier scour occurred at the \n500-year discharge. Additional information on scour depths and depths to armoring are \nincluded in the section titled “Scour Results”. Scoured-streambed elevations, based on the \ncalculated scour depths, are presented in tables 1 and 2. A cross-section of the scour \ncomputed at the bridge is presented in figure 8. Scour depths were calculated assuming an \ninfinite 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/ofr97342","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 43 (CHESVT00110043) on State Highway 11, crossing the Middle Branch Williams River, Chester, Vermont: U.S. Geological Survey Open-File Report 97-342, iv, 50 p., https://doi.org/10.3133/ofr97342.","productDescription":"iv, 50 p.","numberOfPages":"55","costCenters":[],"links":[{"id":169723,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/usgs_thumb.jpg"},{"id":279771,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0342/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 ], [ -72.625,43.375 ], [ -72.625,43.25 ], [ -72.75,43.25 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a614c","contributors":{"authors":[{"text":"Striker, Lora K.","contributorId":41481,"corporation":false,"usgs":true,"family":"Striker","given":"Lora","email":"","middleInitial":"K.","affiliations":[],"preferred":false,"id":240468,"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":240469,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":49915,"text":"ofr97343 - 1997 - Level II scour analysis for Bridge 53 (WILMVT01000053) on State Route 100, crossing Cold Brook, Wilmington, Vermont","interactions":[],"lastModifiedDate":"2014-01-05T13:06:31","indexId":"ofr97343","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":"97-343","title":"Level II scour analysis for Bridge 53 (WILMVT01000053) on State Route 100, crossing Cold Brook, Wilmington, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nWILMVT01000053 on State Route 100 crossing Cold Brook, Wilmington, 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 \nsouth-central Vermont. The 8.38-mi2 drainage area is in a predominantly rural and forested \nbasin. In the vicinity of the study site, the surface cover predominantly is pasture except for \nthe immediate channel banks, which are tree covered.
\nIn the study area, Cold Brook has a straight channel with a slope of approximately 0.04 ft/ft, \nan average channel top width of 63 feet and an average bank height of 9 feet. The channel is \nconstructed with stone fill completely covering both banks for 300 feet upstream of the site. \nThe predominant channel bed materials are gravel and cobbles with a median grain size \n(D50) of 66.2 mm (0.217 ft). The geomorphic assessment at the time of the Level I and \nLevel II site visit on August 7, 1996, indicated that the reach was constructed.
\nThe State Route 100 crossing of Cold Brook is a 23-ft-long, two-lane bridge divided by a \nmedian strip consisting of one 20-foot concrete span (Vermont Agency of Transportation, \nwritten communication, November 1, 1995). The bridge is supported by vertical, concrete \nabutments with wingwalls. The channel is not skewed to the opening and the opening-skew-\nto-roadway also is zero degrees.
\nThe scour protection measure at the site was type-2 stone fill (less than 36 inches diameter) \non the upstream banks, the upstream wingwalls, and the downstream left wingwall. \nAdditional details describing conditions at the site are included in the Level II Summary \nand Appendices D and E.
\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a \nhighway crossing is comprised of three components: 1) long-term streambed degradation; \n2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) \nand; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is \nthe sum of the three components. Equations are available to compute depths for contraction \nand local scour and a summary of the results of these computations follows.
\nContraction scour for all modelled flows ranged from 0.6 to 2.7 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour ranged from 4.8 to \n10.9 ft. The worst-case abutment scour occurred at the left abutment for the 500-year \ndischarge. 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/ofr97343","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Boehmler, E.M., 1997, Level II scour analysis for Bridge 53 (WILMVT01000053) on State Route 100, crossing Cold Brook, Wilmington, Vermont: U.S. Geological Survey Open-File Report 97-343, iv, 49 p., https://doi.org/10.3133/ofr97343.","productDescription":"iv, 49 p.","numberOfPages":"54","costCenters":[],"links":[{"id":170176,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/usgs_thumb.jpg"},{"id":279770,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0343/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Wilmington","otherGeospatial":"Cold 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":"4f4e4b17e4b07f02db6a5b46","contributors":{"authors":[{"text":"Boehmler, Erick M.","contributorId":96303,"corporation":false,"usgs":true,"family":"Boehmler","given":"Erick","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":240470,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49917,"text":"ofr97345 - 1997 - Level II scour analysis for Bridge 11R (ROCKTH0001011R) on Town Highway 1 (VT 121 & FAS 125), crossing the Saxtons River, Rockingham, Vermont","interactions":[],"lastModifiedDate":"2014-01-05T12:42:26","indexId":"ofr97345","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":"97-345","title":"Level II scour analysis for Bridge 11R (ROCKTH0001011R) on Town Highway 1 (VT 121 & FAS 125), crossing the Saxtons River, Rockingham, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nROCKTH0001011R on Town Highway 1 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 68.3-mi2\n drainage area is in a predominantly rural and \nforested basin. In the vicinity of the study site, the surface cover consists of houses, short \ngrass, and scattered trees except along the immediate river banks, which are tree covered.
\nIn the study area, the Saxtons River has a sinuous channel with a slope of approximately \n0.005 ft/ft, an average channel top width of 121 ft and an average bank height of 8 ft. The \npredominant channel bed materials are gravel and cobbles with a median grain size (D50) of \n109 mm (0.359 ft). The geomorphic assessment at the time of the Level I and Level II site \nvisit on September 3, 1996, indicated that the reach was laterally unstable. Lateral \ninstability was evident with respect to a cut-bank on the left bank upstream with slip failure \nof bank material. Furthermore, there is a wide point bar along the right bank upstream \nopposite the cut-bank.
\nThe Town Highway 1 crossing of the Saxtons River is a 184-ft-long, two-lane bridge \nconsisting of three steel-beam spans (Vermont Agency of Transportation, written communication, March 30, 1995). \nThe bridge is supported by vertical, concrete, skeletal-style abutment walls with spill-through embankments adjacent to \neach wall. The channel is skewed approximately 35 degrees to the opening while the opening-skew-to-roadway is 30 \ndegrees.
\nThe only scour protection measure at the site was type-3 stone fill (less than 48 inches \ndiameter) on the spill-through embankments. Additional details describing conditions at the \nsite are included in the Level II Summary and Appendices D \nand E.
\nScour depths and rock rip-rap sizes were computed using the general guidelines described \nin Hydraulic Engineering Circular 18 (Richardson and others, 1995). Total scour at a \nhighway crossing is comprised of three components: 1) long-term streambed degradation; \n2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) \nand; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is \nthe sum of the three components. Equations are available to compute depths for contraction \nand local scour and a summary of the results of these computations follows.
\nThere was no computed contraction scour for all modelled flows at this site. Abutment \nscour ranged from 9.0 to 13.4 feet. The worst-case abutment scour occurred at the 500-year \ndischarge for the left abutment. There are two piers for which computed pier scour ranged \nfrom 9.0 to 18.4 feet. The left and right piers in this report are presented as pier 1 and pier 2, \nrespectively. The worst-case pier scour occurred at pier 2 for the 500-year 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/ofr97345","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Boehmler, E.M., 1997, Level II scour analysis for Bridge 11R (ROCKTH0001011R) on Town Highway 1 (VT 121 & FAS 125), crossing the Saxtons River, Rockingham, Vermont: U.S. Geological Survey Open-File Report 97-345, iv, 49 p., https://doi.org/10.3133/ofr97345.","productDescription":"iv, 49 p.","numberOfPages":"54","costCenters":[],"links":[{"id":170100,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97345.GIF"},{"id":279768,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0345/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":"4f4e4b1ae4b07f02db6a83de","contributors":{"authors":[{"text":"Boehmler, Erick M.","contributorId":96303,"corporation":false,"usgs":true,"family":"Boehmler","given":"Erick","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":240472,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49918,"text":"ofr97346 - 1997 - Level II scour analysis for Bridge 43 (BENNCYDEPO0043) on Depot Street, crossing the Walloomsac River, Bennington, Vermont","interactions":[],"lastModifiedDate":"2014-01-05T12:21:42","indexId":"ofr97346","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":"97-346","title":"Level II scour analysis for Bridge 43 (BENNCYDEPO0043) on Depot Street, crossing the Walloomsac River, Bennington, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nBENNCYDEPO0043 on the Depot Street crossing of the Walloomsac River, Bennington, \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 Green Mountain section of the New England physiographic province in \nsouthwestern Vermont. The 30.1-mi2\n drainage area is a predominantly rural and forested \nbasin. The bridge site is located within an urban setting in the Town of Bennington with \nbuildings and parking lots on overbanks.
\nIn the study area, the Walloomsac River has a straight channel with constructed channel \nbanks through much of the reach. The channel is located on a delta and has a slope of \napproximately 0.02 ft/ft, an average channel top width of 48 ft and an average bank height \nof 6 ft. The predominant channel bed material is cobble with a median grain size (D50) of \n108 mm (0.356 ft). The geomorphic assessment at the time of the Level I and Level II site \nvisit on August 5, 1996, indicated that the reach was stable.
\nThe Depot Street crossing of the Walloomsac River is a 46-ft-long, two-lane bridge \nconsisting of one 40-foot concrete span (Vermont Agency of Transportation, written \ncommunication, December 13, 1995). The bridge is supported by vertical, concrete \nabutments with wingwalls. The channel is skewed approximately \n5 degrees to the opening and the opening-skew-to-roadway is 15 degrees.
\nScour countermeasures at the site include type-2 stone fill (less than 36 inches diameter) at \nthe upstream end of the upstream right wing wall and type-1 stone fill (less than 12 inches \ndiameter) along the base of the upstream left wing wall. Downstream banks are protected by \nconcrete and stone walls. The upstream right bank is protected by alternating type-2 stone \nfill and masonry walls. Additional details describing conditions at the site are included in \nthe 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 computed for all modelled flows ranged from 0.0 to 4.1 ft. \nThe worst-case contraction scour occurred at the 500-year discharge. \nComputed right abutment scour ranged from 2.9 to 13.4 ft. with the worst-case \nscour occurring at the 500-year discharge. Computed left abutment scour \nranged from 5.6 to 16.3 ft. with the worst-case scour also occurring at the 500-year discharge. \nAdditional information on scour depths and depths to armoring are included in the section titled \n“Scour Results”. Scoured-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 depths were calculated \nassuming 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/ofr97346","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 (BENNCYDEPO0043) on Depot Street, crossing the Walloomsac River, Bennington, Vermont: U.S. Geological Survey Open-File Report 97-346, iv, 50 p., https://doi.org/10.3133/ofr97346.","productDescription":"iv, 50 p.","numberOfPages":"55","costCenters":[],"links":[{"id":170101,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/usgs_thumb.jpg"},{"id":279767,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0346/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Bennington","otherGeospatial":"Walloomsac River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -73.25,42.75 ], [ -73.25,43.0 ], [ -73.125,43.0 ], [ -73.125,42.75 ], [ -73.25,42.75 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a615b","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":240473,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49919,"text":"ofr97362 - 1997 - Level II scour analysis for Bridge 7 (CHESTH00030007) on Town Highway 3, crossing the South Branch Williams River, Chester, Vermont","interactions":[],"lastModifiedDate":"2014-01-04T15:31:30","indexId":"ofr97362","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":"97-362","title":"Level II scour analysis for Bridge 7 (CHESTH00030007) on Town Highway 3, crossing the South Branch Williams River, Chester, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nCHESTH00030007 on Town Highway 3 which is also State Route 35 crossing the South \nBranch Williams River, Chester, Vermont (figures 1–8). A Level II study is a basic \nengineering analysis of the site, including a quantitative analysis of stream stability and \nscour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation \nalso are included in Appendix E of this report. A Level I investigation provides a qualitative \ngeomorphic characterization of the study site. Information on the bridge, gleaned from \nVermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level \nI and Level II analyses and is found in Appendix D.
\nThe site is in the New England Upland section of the New England physiographic province \nin southern Vermont. The 10.4-mi2 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 right \nbank while the immediate bank has some trees. Downstream of the bridge and the upstream \nleft bank are forested.
\nIn the study area, the South Branch Williams River has an incised, sinuous channel with a \nslope of approximately 0.03 ft/ft, an average channel top width of 65 ft and an average bank \nheight of 4 ft. The channel bed material ranges from gravel to boulder with a median grain \nsize (D50) of 70.5 mm (0.231 ft). The geomorphic assessment at the time of the Level I and \nLevel II site visit on August 26, 1996, indicated that the reach was laterally unstable. There \nare cutbanks on both the left and right banks alternating with point bars in the upstream \nreach.
\nThe Town Highway 3 (VT 35) crossing of the South Branch Williams River is a 74-ft-long, \ntwo-lane bridge consisting of one 72-foot steel-beam span (Vermont Agency of \nTransportation, written communication, March 30, 1995). The bridge is supported by spill-\nthrough abutments. The channel is skewed approximately 5 degrees to the opening and the \nopening-skew-to-roadway is also 5 degrees.
\nThree channel scour holes 1.0 ft deeper than the mean thalweg depth were observed during \nthe Level I assessment in the upstream reach. There are no scour protection measures at the \nsite. 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 0.4 ft. The worst-case \ncontraction scour occurred at the 100-year. Abutment scour ranged from 4.1 to 15.5 ft. The \nworst-case abutment scour occurred at the 500-year. Additional information on scour \ndepths and depths to armoring are included in the section titled “Scour Results”. Scoured-\nstreambed 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-\nsize 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/ofr97362","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Burns, R.L., 1997, Level II scour analysis for Bridge 7 (CHESTH00030007) on Town Highway 3, crossing the South Branch Williams River, Chester, Vermont: U.S. Geological Survey Open-File Report 97-362, iv, 50 p., https://doi.org/10.3133/ofr97362.","productDescription":"iv, 50 p.","numberOfPages":"55","costCenters":[],"links":[{"id":170102,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97362.GIF"},{"id":279766,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0362/report.pdf"}],"scale":"62500","country":"United States","state":"Vermont","city":"Chester","otherGeospatial":"South Branch Williams River","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,43.0 ], [ -72.75,43.5 ], [ -72.5,43.5 ], [ -72.5,43.0 ], [ -72.75,43.0 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b16e4b07f02db6a576d","contributors":{"authors":[{"text":"Burns, Ronda L.","contributorId":71602,"corporation":false,"usgs":true,"family":"Burns","given":"Ronda","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":240474,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49920,"text":"ofr97363 - 1997 - Level II scour analysis for Bridge 86 (VERNVT01420086) on State Route 142, crossing Broad Brook, Vernon, Vermont","interactions":[],"lastModifiedDate":"2014-01-04T15:20:03","indexId":"ofr97363","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":"97-363","title":"Level II scour analysis for Bridge 86 (VERNVT01420086) on State Route 142, crossing Broad Brook, Vernon, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nVERNVT01420086 on State Route 142 crossing Broad Brook, Vernon, 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 23.7-mi2\n drainage area is in a predominantly rural and \nforested basin. In the vicinity of the study site, the surface cover is primarily forest with the \nexception of the downstream left bank which is a wetland.
\nIn the study area, Broad Brook has an incised, meandering channel with a slope of \napproximately 0.001 ft/ft, an average channel top width of 132 ft and an average bank \nheight of 3 ft. The channel bed material ranges from silt to cobbles with a median grain size \n(D50) of 80.0 mm (0.262 ft). The geomorphic assessment at the time of the Level I and \nLevel II site visit on August 14, 1996, indicated that the reach was vertically and laterally \nunstable.
\nThe State Route 142 crossing of Broad Brook is a 98-ft-long, two-lane bridge consisting of \ntwo steel-beam spans with a maximum span length of 47 feet (Vermont Agency of \nTransportation, written communication, March 30, 1995). The bridge is supported by \nvertical, concrete abutments with spill-through slopes and a concrete pier. The channel is \nskewed approximately 30 degrees to the opening while there is no opening-skew-to-\nroadway.
\nA scour hole 2 ft deeper than the mean thalweg depth was observed along the left bank side \nof the pier during the Level I assessment. There was also a scour hole 1 ft deeper than the \nmean thalweg depth observed along the length of the right abutment. The only scour \nprotection measure at the site was type-2 stone fill (less than 36 inches diameter) along the \nentire base length of the spill-through slopes. Additional details describing conditions at the \nsite 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.
\nThere was no computed contraction scour for any modelled flows. Scour at the left \nabutment ranged from 13.2 to 15.9 ft and at the right abutment ranged from 12.0 to 16.3 ft. \nThe worst-case abutment scour occurred at the 500-year discharge. Pier scour ranged from \n12.0 to 16.3 ft. The worst-case pier 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/ofr97363","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Ivanoff, M.A., 1997, Level II scour analysis for Bridge 86 (VERNVT01420086) on State Route 142, crossing Broad Brook, Vernon, Vermont: U.S. Geological Survey Open-File Report 97-363, iv, 55 p., https://doi.org/10.3133/ofr97363.","productDescription":"iv, 55 p.","numberOfPages":"60","costCenters":[],"links":[{"id":170103,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97363.GIF"},{"id":279765,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0363/report.pdf"}],"scale":"25000","country":"United States","state":"Vermont","city":"Vernon","otherGeospatial":"Broad Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.75,42.75 ], [ -72.75,42.875 ], [ -72.5,42.875 ], [ -72.5,42.75 ], [ -72.75,42.75 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b16e4b07f02db6a55e1","contributors":{"authors":[{"text":"Ivanoff, Michael A.","contributorId":27105,"corporation":false,"usgs":true,"family":"Ivanoff","given":"Michael","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":240475,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49922,"text":"ofr97365 - 1997 - Level II scour analysis for Bridge 46 (CHESVT00110046) on Vermont State Route 11, crossing the Middle Branch Williams River, Chester, Vermont","interactions":[],"lastModifiedDate":"2016-08-25T13:33:59","indexId":"ofr97365","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":"97-365","title":"Level II scour analysis for Bridge 46 (CHESVT00110046) on Vermont State Route 11, crossing the Middle Branch Williams River, Chester, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure CHESVT00110046 on State Route 11 crossing the Middle Branch Williams River, Chester, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D.
The site is in the Green Mountain and New England Upland sections of the New England physiographic province in southeastern Vermont. The 28.0-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is forested on the upstream left and downstream right overbanks. The upstream right and downstream left overbanks are pasture while the immediate banks have dense woody vegetation.
In the study area, the the Middle Branch Williams River has an incised, sinuous channel with a slope of approximately 0.013 ft/ft, an average channel top width of 81 ft and an average bank height of 11 ft. The channel bed material ranges from gravel to bedrock with a median grain size (D50) of 70.7 mm (0.232 ft). The geomorphic assessment at the time of the Level I and Level II site visit on September 12, 1996, indicated that the reach was stable.
The State Route 11 crossing of the Middle Branch Williams River is a 118-ft-long, two-lane steel stringer type bridge consisting of a 114-foot steel plate deck (Vermont Agency of Transportation, written communication, March 29, 1995). The opening length of the structure parallel to the bridge face is 109 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 50 degrees.
A scour hole 2 ft deeper than the mean thalweg depth was observed 128 feet downstream during the Level I assessment. Type-1 (less than 1 foot) stone fill protects the downstream right wingwall. Type-2 (less than 3 ft diameter) stone fill protects the upstream right wingwall, the left and right abutments, the upstream left and right 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.
There was no computed contraction scour for any modelled flows. Abutment scour ranged from 7.0 to 10.3 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/ofr97365","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Wild, E.C., 1997, Level II scour analysis for Bridge 46 (CHESVT00110046) on Vermont State Route 11, crossing the Middle Branch Williams River, Chester, Vermont: U.S. Geological Survey Open-File Report 97-365, iv, 48 p., https://doi.org/10.3133/ofr97365.","productDescription":"iv, 48 p.","numberOfPages":"53","costCenters":[],"links":[{"id":170454,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97365.PNG"},{"id":279762,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0365/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Chester","otherGeospatial":"Middle Branch Williams 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":"4f4e4b17e4b07f02db6a60cc","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":240478,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49923,"text":"ofr97366 - 1997 - Level II scour analysis for Bridge 1 (JAY-TH00040001) on Town Highway 4, crossing Crook Brook, Jay, Vermont","interactions":[],"lastModifiedDate":"2013-12-20T15:12:12","indexId":"ofr97366","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":"97-366","title":"Level II scour analysis for Bridge 1 (JAY-TH00040001) on Town Highway 4, crossing Crook Brook, Jay, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nJAY-TH00040001 on Town Highway 4 crossing Crook Brook, Jay, Vermont (figures 1–8). \nA Level II study is a basic engineering analysis of the site, including a quantitative analysis \nof stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level \nI scour investigation also are included in Appendix E of this report. A Level I investigation \nprovides a qualitative geomorphic characterization of the study site. Information on the \nbridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled \nprior to conducting Level I and Level II analyses and is found in Appendix D.
\nThe site is in the Green Mountain section of the New England physiographic province in \nnorthern Vermont. The 20.7-mi2\n drainage area is in a predominantly rural and forested \nbasin. In the vicinity of the study site, the surface cover is thick woody vegetation and/or \nforest except for the upstream right bank and overbank which is pasture.
\nIn the study area, Crook Brook has an incised, sinuous channel with a slope of \napproximately 0.02 ft/ft, an average channel top width of 86 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 48.7 mm (0.160 ft). The geomorphic assessment at the time of the Level I and \nLevel II site visit on June 5, 1995, indicated that the reach was stable.
\nThe Town Highway 4 crossing of Crook Brook is a 49-ft-long, two-lane bridge consisting \nof one 45-foot concrete span (Vermont Agency of Transportation, written communication, \nMarch 6, 1995). The opening length of the structure parallel to the bridge face is 42 ft.The \nbridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed \napproximately 5 degrees to the opening. The opening-skew-to-roadway is also 5 degrees. \nChannel scour is present along the left abutment. The scoured area was 1.5 ft deeper than \nthe mean thalweg depth during the Level I assessment. Scour countermeasures include \ntype-2 stone fill (less than 36 inches diameter) on the upstream and downstream sides of the \nleft road embankment and at the upstream end of the left abutment. There is type-3 stone fill \n(less than 48 inches diameter) along the base 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 2.5 to 3.8 ft. The worst-case \ncontraction scour occurred at the 500-year discharge. Abutment scour at the left abutment \nranged from 15.4 to 18.5 ft. Abutment scour at the right abutment ranged from 12.3 to 15.3 \nft. The worst-case abutment scour occurred at the 500-year discharge for both abutments. \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/ofr97366","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Olson, S.A., 1997, Level II scour analysis for Bridge 1 (JAY-TH00040001) on Town Highway 4, crossing Crook Brook, Jay, Vermont: U.S. Geological Survey Open-File Report 97-366, iv, 48 p., https://doi.org/10.3133/ofr97366.","productDescription":"iv, 48 p.","numberOfPages":"53","costCenters":[],"links":[{"id":170455,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97366.PNG"},{"id":279759,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0366/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Jay","otherGeospatial":"Crook Brook","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -72.5,44.875 ], [ -72.5,45.0 ], [ -72.375,45.0 ], [ -72.375,44.875 ], [ -72.5,44.875 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b17e4b07f02db6a5be3","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":240479,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":49927,"text":"ofr97372 - 1997 - Level II scour analysis for Bridge 25 (ANDOTH00230025) on Town Highway 23, crossing Andover Branch, Andover, Vermont","interactions":[],"lastModifiedDate":"2013-12-20T11:48:37","indexId":"ofr97372","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":"97-372","title":"Level II scour analysis for Bridge 25 (ANDOTH00230025) on Town Highway 23, crossing Andover Branch, Andover, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nANDOTH00230025 on Town Highway 23 crossing the Andover Branch, Andover, \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 Green Mountain section of the New England physiographic province in \nsouth-central Vermont. The 6.74-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 right overbank and \nforest on the left overbank while the immediate banks, both upstream and downstream, are \nforested.
\nIn the study area, the Andover Branch has an incised, sinuous channel with a slope of \napproximately 0.02 ft/ft, an average channel top width of 55 ft and an average bank height \nof 9 ft. The channel bed material ranges from gravel to boulder with a median grain size \n(D50) of 78.4 mm (0.257 ft). The geomorphic assessment at the time of the Level I and \nLevel II site visit on August 27, 1996, indicated that the reach was stable.
\nThe Town Highway 23 crossing of the Andover Branch is a 25-ft-long, two-lane structure \nconsisting of a multi-plate corrugated steel arch culvert with concrete footings (Vermont \nAgency of Transportation, written communication, March 29, 1995). The culvert is mitered \nat the inlet and outlet. The channel is skewed approximately zero degrees to the opening \nwhile the opening-skew-to-roadway is zero degrees.
\nThe footings are exposed approximately 1.25 ft, with the exception of the downstream end \nof the right footing which is exposed approximately 0.5 ft. The only scour protection \nmeasure at the site was type-2 stone fill (less than 36 inches diameter) along the upstream \nleft bank. 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 modelled flows ranged from 1.6 to 2.8 ft. The worst-case contraction \nscour occurred at the 500-year discharge. Abutment scour ranged from 10.0 to 11.7 ft along \nthe left footing and from 11.8 to 16.7 along the right footing. 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.
\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/ofr97372","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Flynn, R.H., and Burns, R.L., 1997, Level II scour analysis for Bridge 25 (ANDOTH00230025) on Town Highway 23, crossing Andover Branch, Andover, Vermont: U.S. Geological Survey Open-File Report 97-372, iv, 47 p., https://doi.org/10.3133/ofr97372.","productDescription":"iv, 47 p.","numberOfPages":"52","costCenters":[],"links":[{"id":170522,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97372.PNG"},{"id":279755,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0372/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":"4f4e4b1ae4b07f02db6a8099","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":240486,"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":240487,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"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":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":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":49931,"text":"ofr97376 - 1997 - Level II scour analysis for Bridge 25 (JAMATH00010025) on Town Highway 1, crossing Ball Mountain Brook, Jamaica, Vermont","interactions":[],"lastModifiedDate":"2013-12-20T11:18:25","indexId":"ofr97376","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":"97-376","title":"Level II scour analysis for Bridge 25 (JAMATH00010025) on Town Highway 1, crossing Ball Mountain Brook, Jamaica, Vermont","docAbstract":"This report provides the results of a detailed Level II analysis of scour potential at structure \nJAMATH00010025 on Town Highway 1 crossing Ball Mountain Brook, Jamaica, 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 \nsouthern Vermont. The 29.5-mi2\n drainage area is in a predominantly rural and forested \nbasin. In the vicinity of the study site, the surface cover is forest except on the downstream \nright bank which is pasture with some trees along the channel.
\nIn the study area, Ball Mountain Brook has an incised, straight channel with a slope of \napproximately 0.021 ft/ft, an average channel top width of 86 ft and an average bank height \nof 9 ft. The channel bed material ranges from gravel to bedrock with a median grain size \n(D50) of 222 mm (0.727 ft). The geomorphic assessment at the time of the Level I and \nLevel II site visit on August 13, 1996, indicated that the reach was stable.
\nThe Town Highway 1 crossing of Ball Mountain Brook is a 78-ft-long, two-lane bridge \nconsisting of one 75-foot steel-beam span (Vermont Agency of Transportation, written \ncommunication, March 29, 1995). The opening length of the structure parallel to the bridge \nface is 73 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The \nchannel is skewed approximately 30 degrees to the opening while the opening-skew-to-roadway is 30 degrees.
\nA scour hole 1.0 ft deeper than the mean thalweg depth was observed at the upstream bridge \nface. The scour protection measures at the site were type-2 stone fill (less than 36 inches \ndiameter) along the upstream banks and along both abutments, and type-3 stone fill (less \nthan 48 inches diameter) along the downstream banks. 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 only occurred at the 500-year discharge and was 0.1 ft. Abutment scour \nranged from 11.2 to 15.7 ft. The worst-case abutment scour occurred at the 500-year \ndischarge. 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/ofr97376","collaboration":"Prepared in cooperation with Vermont Agency of Transportation and Federal Highway Administration","usgsCitation":"Burns, R.L., 1997, Level II scour analysis for Bridge 25 (JAMATH00010025) on Town Highway 1, crossing Ball Mountain Brook, Jamaica, Vermont: U.S. Geological Survey Open-File Report 97-376, iv, 48 p., https://doi.org/10.3133/ofr97376.","productDescription":"iv, 48 p.","numberOfPages":"53","costCenters":[],"links":[{"id":170526,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/ofr97376.PNG"},{"id":279751,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1997/0376/report.pdf"}],"scale":"24000","country":"United States","state":"Vermont","city":"Jamaica","otherGeospatial":"Ball Mountain 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":"4f4e4b1ae4b07f02db6a8064","contributors":{"authors":[{"text":"Burns, Ronda L.","contributorId":71602,"corporation":false,"usgs":true,"family":"Burns","given":"Ronda","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":240494,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"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":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":49934,"text":"ofr97379 - 1997 - Level II scour analysis for Bridge 72 (STRATH00510072) on Town Highway 51, crossing the West Branch Ompompanoosuc River, Strafford, Vermont","interactions":[],"lastModifiedDate":"2016-08-25T13:35:36","indexId":"ofr97379","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":"97-379","title":"Level II scour analysis for Bridge 72 (STRATH00510072) on Town Highway 51, crossing the West Branch Ompompanoosuc River, Strafford, Vermont","docAbstract":"No abstract available.
","language":"English","publisher":"U.S. Geological Survey","doi":"10.3133/ofr97379","usgsCitation":"Wild, E.C., 1997, Level II scour analysis for Bridge 72 (STRATH00510072) on Town Highway 51, crossing the West Branch Ompompanoosuc River, Strafford, Vermont: U.S. Geological Survey Open-File Report 97-379, 50 p., https://doi.org/10.3133/ofr97379.","productDescription":"50 p.","costCenters":[],"links":[{"id":169724,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/usgs_thumb.jpg"}],"country":"United States","state":"Vermont","city":"Strafford","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b16e4b07f02db6a56ed","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":240499,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ]}